WorldWideScience

Sample records for catalytic cracking units

  1. 40 CFR Table 8 to Subpart Uuu of... - Organic HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... unit must not exceed 500 parts per million volume (ppmv) (dry basis). 2. Not subject to the NSPS for CO... Catalytic Cracking Units 8 Table 8 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL... Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Pt. 63, Subpt....

  2. Failure analysis of corrosion cracking and simulated testing for a fluid catalytic cracking unit

    Institute of Scientific and Technical Information of China (English)

    Hua Chen; Xiaogang Li; Chaofang Dong; Ming Li; Jinwen Yang

    2005-01-01

    The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium presented on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some suggestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.

  3. A Fluid Catalytic Cracking Unit Designed to Process Daqing Vacuum Residua

    Institute of Scientific and Technical Information of China (English)

    Wu Xiuzhang; Du Guosheng

    2000-01-01

    @@The crude distillation capacity of Beijing Yanshan Petrochemical Company Limited(BYPC) of SINOPEC is 8.5 Mt/a. The crude oil processed is mostly Daqing crude oil. Due to the diversified demand of the oil mar ket, the heavy oil can hardly be sold in the summer season. If the excess residue is processed, the light oil products yield and the benefit of BYPC will be in creased. So the fluid catalytic cracking unit (FCCU) with a capacity of 800kt/a was revamped to process Daqing vacuum residue in 1998.

  4. A catalytic cracking process

    Energy Technology Data Exchange (ETDEWEB)

    Degnan, T.F.; Helton, T.E.

    1995-07-20

    Heavy oils are subjected to catalytic cracking in the absence of added hydrogen using a catalyst containing a zeolite having the structure of ZSM-12 and a large-pore crystalline zeolite having a Constraint Index less than about 1. The process is able to effect a bulk conversion of the oil at the same time yielding a higher octane gasoline and increased light olefin content. (author)

  5. HYDROGEN TRANSFER IN CATALYTIC CRACKING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen transfer is an important secondary reaction of catalytic cracking reactions, which affects product yield distribution and product quality. It is an exothermic reaction with low activation energy around 43.3 kJ/mol. Catalyst properties and operation parameters in catalytic cracking greatly influence the hydrogen transfer reaction. Satisfactory results are expected through careful selection of proper catalysts and operation conditions.

  6. Catalytic cracking of lignites

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, M.; Nowak, S.; Naegler, T.; Zimmermann, J. [Hochschule Merseburg (Germany); Welscher, J.; Schwieger, W. [Erlangen-Nuernberg Univ. (Germany); Hahn, T. [Halle-Wittenberg Univ., Halle (Germany)

    2013-11-01

    A most important factor for the chemical industry is the availability of cheap raw materials. As the oil price of crude oil is rising alternative feedstocks like coal are coming into focus. This work, the catalytic cracking of lignite is part of the alliance ibi (innovative Braunkohlenintegration) to use lignite as a raw material to produce chemicals. With this new one step process without an input of external hydrogen, mostly propylene, butenes and aromatics and char are formed. The product yield depends on manifold process parameters. The use of acid catalysts (zeolites like MFI) shows the highest amount of the desired products. Hydrogen rich lignites with a molar H/C ratio of > 1 are to be favoured. Due to primary cracking and secondary reactions the ratio between catalyst and lignite, temperature and residence time are the most important parameter to control the product distribution. Experiments at 500 C in a discontinuous rotary kiln reactor show yields up to 32 wt-% of hydrocarbons per lignite (maf - moisture and ash free) and 43 wt-% char, which can be gasified. Particularly, the yields of propylene and butenes as main products can be enhanced four times to about 8 wt-% by the use of catalysts while the tar yield decreases. In order to develop this innovative process catalyst systems fixed on beads were developed for an easy separation and regeneration of the used catalyst from the formed char. (orig.)

  7. Performance Assessment of Sintered Metal Fiber Filters in Fluid Catalytic Cracking Unit

    Directory of Open Access Journals (Sweden)

    Liang Yang

    2014-01-01

    Full Text Available A long-term test was performed in a fluid catalytic cracking (FCC hot gas filtration facility using sintered metal candle filters. The operating temperature and pressure were maximum 55°C and 0.28 MPa, respectively. Specific particle sampling systems were used to measure the particle size and concentration directly at high temperature. The range of inlet particle concentration is from 150 to 165 mg/Nm3. The outlet particle concentration is in the range of 0.71–2.77 mg/Nm3 in stable operation. The filtration efficiency is from 98.23% to 99.55%. The inlet volume median diameter and the outlet volume median diameter of the particle are about 1 μm and 2.2 μm, respectively. The cake thickness is calculated based on the equation of Carman-Kozeny. The effects of operating parameters including face velocity, gas cleaning pressure, pulse duration, and maximum pressure drop were investigated. The optimal operating conditions and cleaning strategies were determined. The results show that sintered metal fiber filters are suitable for industrial application due to the good performance and high efficiency observed.

  8. Conversion of toluene to benzene and mixed xylenes on old Thermofor Catalytic Cracking Units (TCC) in Russia

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Alfonso; Usachev, Nikolai Y.; Kalinin, Valera P. [Russian Academy of Sciences, Moscow (Russian Federation). Zelinsky Institute of Organic Chemistry]. E-mails: romero@orc.ru; ny@ioc.ac.ru

    2004-07-01

    World demand on toluene was in regression during the last years due to environmental and economical reasons, and there is a surplus of this compound from the processing to the petrochemical products. Disproportionation and transalkylation for the production of benzene and xylenes from toluene are now important industrial processes (Ikai Wang, 1999.). We analyze here the possibility of processing toluene on the Russian 43-102 'Houdry' type continuous Catalytic Cracking units (TCC), by studying the behaviour of EMCAT-100 catalyst on the disproportionation of toluene under the VHSV, temperature and catalyst/feed mass ratio characteristic for 43-102 facilities. Our previous results show that toluene disproportionation could be carried out on the Russian TCC units. (author)

  9. Maximizing light olefins production in fluid catalytic cracking (FCC) units; Maximizacao de olefinas leves em unidades de craqueamento catalitico fluido

    Energy Technology Data Exchange (ETDEWEB)

    Pimenta, Ricardo D.M.; Pinho, Andrea de Rezende [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The Fluid Catalytic Cracking (FCC) process is widely spread over the ten PETROBRAS refineries in its thirteen industrial units. The importance of the FCC process resides on its high gasoline output, being the main supplier of this important product to the system. Additionally, FCC process is the main source of light hydrocarbons in the LPG range, including light olefins. The increasing demand for ethylene, propylene and butylenes was encouraging to concentrate the research efforts on studies about alternatives for the traditional FCC process. In the present work, the proposals from main licensors (UOP, KBR, Stone and Webster) for a light-olefins-driven FCC process (Petrochemical FCC) will be compared. Furthermore, the catalytic route for light olefins production in FCC units is also described. An additive based on ZSM- 5 zeolite, which is produced following a PETROBRAS proprietary technology, is being largely applied into the catalyst inventories of all FCC units. An analysis of different scenarios was performed to estimate the maximum potential of light olefins production from the highest possible ZSM-5 additive usage. More specifically for the case of ethylene, which production is also boosted by the same type of additive, studies are being conducted with the objective of recovering it from a C2 stream using specific units to do the splitting (UPGR). The search for increasing light olefins production in the refining processes is in line with PETROBRAS strategic plan which targeted for the company a more intense activity in the Brazilian petrochemical market (author)

  10. Reaction Mechanism for the Formation of Nitrogen Oxides (NO x ) During Coke Oxidation in Fluidized Catalytic Cracking Units

    KAUST Repository

    Chaparala, Sree Vidya

    2015-06-11

    Fluidized catalytic cracking (FCC) units in refineries process heavy feedstock obtained from crude oil distillation. While cracking feed, catalysts get deactivated due to coke deposition. During catalyst regeneration by burning coke in air, nitrogen oxides (NOx) are formed. The increase in nitrogen content in feed over time has resulted in increased NOx emissions. To predict NOx concentration in flue gas, a reliable model for FCC regenerators is needed that requires comprehensive understanding and accurate kinetics for NOx formation. Based on the nitrogen-containing functional groups on coke, model molecules are selected to study reactions between coke-bound nitrogen and O2 to form NO and NO2 using density functional theory. The reaction kinetics for the proposed pathways are evaluated using transition state theory. It is observed that the addition of O2 on coke is favored only when the free radical is present on the carbon atom instead of nitrogen atom. Thus, NOx formation during coke oxidation does not result from the direct attack by O2 on N atoms of coke, but from the transfer of an O atom to N from a neighboring site. The low activation energies required for NO formation indicate that it is more likely to form than NO2 during coke oxidation. The favorable pathways for NOx formation that can be used in FCC models are identified. Copyright © 2015 Taylor & Francis Group, LLC.

  11. FUZZY MODELING APPLICATION OF FLUID CATALYTIC CRACKING UNIT (FCCU OF A PETROLEUM REFINERY (TÜPRAŞ

    Directory of Open Access Journals (Sweden)

    Mithat ZEYDAN

    2004-01-01

    Full Text Available In this study, fuzzy modeling of FCCU in the refinery system as the most important part of Petrochemical Industry was carried out. FCCU is the most important unit in the refinery system as it is a higly nonlinear system with MIMO (Multi input-multi output, internal feedback, strongly coupling, time-varying, distributed parameter, significantly uncertain behaviours in nature. Mathematical Models is not enough to identify this system. On the occasion of this, FCCU has a characteristic specifications as a subject of Fuzzy Logic.

  12. Low efficiency deasphalting and catalytic cracking

    International Nuclear Information System (INIS)

    This patent describes a process for converting an asphaltene and metals containing heavy hydrocarbon feed to lighter, more valuable products the metals comprising Ni and V. It comprises: demetallizing the feed by deasphalting the feed in a solvent deasphalting means operating at solvent deasphalting conditions including a solvent: feed volume ratio of about 1:1 to 4:1, using a solvent selected from the group of C4 to 400 degrees F. hydrocarbons and mixtures thereof; recovering from the solvent rich fraction a demetallized oil intermediate product, having a boiling range and containing at least 10 wt.% of the asphaltenes, and 5 to 30% of the Ni and V, and at least 10 wt.% of the solvent present in the solvent rich phase produced in the deasphalting means; catalytically cracking the demetallized oil intermediate product in a catalytic cracking means operating at catalytic cracking conditions to produce a catalytically cracked product vapor fraction having a lower boiling range than the boiling range of the demetallized oil intermediate product; and fractionating the catalytically cracked product in a fractionation means to produce catalytically cracked product fractions

  13. Commercial Test of Flexible Dual-Riser Catalytic Cracking Process

    Institute of Scientific and Technical Information of China (English)

    Tang Haitao; Wang Longyan; Wang Guoliang; Zhang Lixin; Wei Jialu; Chen Zhenghong; Teng Tiancan; Sun Zhonghang

    2003-01-01

    The technical features and commercial test results of flexible dual-riser fluidized catalytic cracking(FDFCC) process are presented for refiners to choose an efficient process to upgrade FCC naphtha and boostpropylene production in a RFCC unit. The commercial test results indicate that the olefin content of catalyti-25% and RON increased by 0.5-2 units in a RFCC unit. In addition, propylene yield and the production ratioof diesel to gasoline can also be remarkably enhanced in the RFCC unit.

  14. Fluid catalytic cracking of biomass pyrolysis vapors

    Energy Technology Data Exchange (ETDEWEB)

    Mante, Ofei Daku [Virginia Polytechnic Institute and State University, Biological Systems Engineering, Blacksburg, VA (United States); Agblevor, Foster A. [Utah State University, Biological Engineering, Logan, UT (United States); McClung, Ron [BASF Inc, Florham, NJ (United States)

    2011-12-15

    Catalytic cracking of pyrolysis oils/vapors offers the opportunity of producing bio-oils which can potentially be coprocessed with petroleum feedstocks in today's oil refinery to produce transportation fuel and chemicals. Catalyst properties and process conditions are critical in producing and maximizing desired product. In our studies, catalyst matrix (kaolin) and two commercial fluid catalytic cracking (FCC) catalysts, FCC-H and FCC-L, with different Y-zeolite contents were investigated. The catalytic cracking of hybrid poplar wood was conducted in a 50-mm bench-scale bubbling fluidized-bed pyrolysis reactor at 465 C with a weight hourly space velocity of 1.5 h{sup -1}. The results showed that the yields and quality of the bio-oils was a function of the Y-zeolite content of the catalyst. The char/coke yield was highest for the higher Y-zeolite catalyst. The organic liquid yields decreased inversely with increase in zeolite content of the catalyst whereas the water and gas yields increased. Analysis of the oils by both Fourier-transform infrared and {sup 13}C-nuclear magnetic resonance indicated that the catalyst with higher zeolite content (FCC-H) was efficient in the removal of compounds like levoglucosan, carboxylic acids and the conversion of methoxylated phenols to substituted phenols and benzenediols. The cracking of pyrolysis products by kaolin suggests that the activity of the FCC catalyst on biomass pyrolysis vapors can be attributed to both Y-zeolite and matrix. The FCC-H catalyst produced much more improved oil. The oil was low in oxygen (22.67 wt.%), high in energy (29.79 MJ/kg) and relatively stable over a 12-month storage period. (orig.)

  15. Aluminosilicate nanoparticles for catalytic hydrocarbon cracking.

    Science.gov (United States)

    Liu, Yu; Pinnavaia, Thomas J

    2003-03-01

    Aluminosilicate nanoparticles containing 9.0-20 nm mesopores were prepared through the use of protozeolitic nanoclusters as the inorganic precursor and starch as a porogen. The calcined, porogen-free composition containing 2 mol % aluminum exhibited the porosity, hydrothermal stability, and acidity needed for the cracking of very large hydrocarbons. In fact, the hydrothermal stability of the nanoparticles to pure steam at 800 degrees C, along with the cumene cracking activity, surpassed the analogous performance properties of ultrastable Y zeolite, the main catalyst component of commercial cracking catalysts. The remarkable hydrothermal stability and catalytic reactivity of the new nanoparticles are attributable to a unique combination of two factors, the presence of protozeolitic nanoclusters in the pore walls and the unprecedented pore wall thickness (7-15 nm). In addition, the excellent catalytic longevity of the nanoparticles is most likely facilitated by the small domain size of the nanoparticles that greatly improves access to the acid sites on the pore walls and minimizes the diffusion length of coke precursors out of the pores. PMID:12603109

  16. Optimization of the fluid catalytic cracking unit performance by application of a high motor Octane catalyst and reduction of gasoline vapour pressure

    International Nuclear Information System (INIS)

    Full text: The fluid catalytic cracking (FCC) gasoline is the main contributor to the refinery gasoline pool in the LUKOIL Neftohim Burgas (LNB) refinery. Next in quantity contributor in the refinery gasoline pool is the reformate. The FCC gasoline sensitivity (MON-RON) is about 12 points. The reformer gasoline sensitivity is 11 points. The high sensitivity of the main contributors to the LNB refinery gasoline pool leads to a shortage in the motor octane number. For that reason a selection of an FCC catalyst that is capable of increasing the motor octane number of the FCC gasoline was performed. The application of this catalyst in the LNB FCC unit has led to an increase of the motor octane number of the FCC gasoline by 0.5 points, which enabled the refinery to increase the production of automotive gasolines by 1.3 % and to increase the share of premium automotive gasoline by 5 %. This had an effect of improvement of the refinery economics by a six figure number of US $ per year. The optimization of the FCC gasoline Reid Vapor Pressure (RVP) during the winter season, consisting in a reduction of the RVP from 60 to 50 kPa and an increase of the FCC C4 olefins yield, has led to an augmentation of high motor octane number alkylate production. As a result the refinery economics was improved by a five figure number of US $ per year. key words: FCC gasoline motor octane number, gasoline RVP, FCC operation profitability

  17. 7-lump kinetic model for residual oil catalytic cracking

    Institute of Scientific and Technical Information of China (English)

    XU Ou-guan; SU Hong-ye; MU Sheng-jing; CHU Jian

    2006-01-01

    In this paper a novel 7-lump kinetic model is proposed to describe residual oil catalytic cracking, in which coke is lumped separately for accurate prediction. The reactor block is modeled as a combination of an ideal pipe flow reactor (PFR)and a continuously stirred tank reactor (CSTR). Unit factors are designed to correct the deviation between model predictions and practical plant data and tuned by modified Levenberg-Marquardt algorithm. The parameters estimated are reliable and good agreement between the model predictions and plant observations is observed. The model helps us get good insight into the performance of an industrial riser reactor that would be useful for optimization of residual oil catalytic cracking.

  18. Catalytic oxidative cracking of hexane as a route to olefins

    NARCIS (Netherlands)

    Boyadjian, Cassia; Lefferts, Leon; Seshan, K.

    2010-01-01

    Catalytic oxidative cracking of naphtha is conceptually an alternative process to steam cracking. The performance of sol–gel synthesized Li/MgO in oxidative cracking of hexane as a model compound of naphtha, has been studied and compared to that of conventionally prepared catalyst. At a temperature

  19. The Affecting Factors to Restrict Increasing Convert Ratio of Fluid Catalytic Cracking Unit%制约提高催化裂化转化率的影响因素分析

    Institute of Scientific and Technical Information of China (English)

    曹小伟

    2012-01-01

    通过运用催化裂化相关理论并结合惠州炼油分公司催化裂化装置的实际生产情况,对影响催化裂化转化率的因素进行了分析,通过分析各操作参数间的相互关系,确定在装置掺炼加氢尾油后,油浆系统是制约提高转化率的关键因素。%On the basis of the fluid catalytic cracking theory,the main process parameters of FCC unit in Huizhou Oil Refining Company were analyzed,that the slurry oil system was the important restrict factor to increase the convert ratio when FCC unit process the feed mixed with hydro-cracking unconverted oil.

  20. Optimized Combination of Residue Hydrodesulfurization and Residue Fluid Catalytic Cracking

    Institute of Scientific and Technical Information of China (English)

    Chen Junwu

    2003-01-01

    @@1 Introduction Combination of residue hydrodesulfurization (HDS) and resi-due fluid catalytic cracking (RFCC) is a unique technologyfor processing high-sulfur residue. This paper discusses theoptimized combination of these two processes.

  1. Kinetics of catalytic cracking with short contact times

    Energy Technology Data Exchange (ETDEWEB)

    Hagelberg, P.; Eilos, I. [Neste Engineering Oy, P.O. Box 310, FIN-06101 Porvoo (Finland); Hiltunen, J.; Lipiaeinen, K.; Niemi, V.M. [Fortum Oil and Gas Oy, P.O. Box 310, FIN-06101 Porvoo (Finland); Aittamaa, J.; Krause, A.O.I. [Department of Chemical Technology, Helsinki University of Technology, P.O. Box 6100, FIN-02015 HUT (Finland)

    2001-01-10

    A novel isothermal pulse reactor was used to study the kinetics of gas oil cracking on a FCC equilibrium catalyst with short contact times. The feed was a lighter gas oil than typically used in FCC-units. Experiments were carried out by varying the catalyst-to-oil ratio, volume of the oil pulse, temperature and residence time. After each hydrocarbon pulse the catalyst was regenerated by introducing several oxygen/nitrogen pulses through the catalyst bed. The amounts of carbon monoxide and carbon dioxide formed were measured and the amount of coke on the catalyst was calculated. The reproducibility of the experiments was excellent. A kinetic model that included five lumps, namely, gas oil, gasoline, liquefied petroleum gas (LPG), dry gas and coke with five cracking reactions was developed first and its kinetic parameters were determined from the experimental results. The data could be best described by the model wherein the rate of cracking of gas oil to gasoline and to LPG were both approximated as second order dependency and the rate of cracking of gas oil to dry gas and to coke as first order dependency on the gas oil concentration. The five-lump model was further enlarged by dividing the gasoline fraction into paraffins, olefins, naphthenes and aromatics resulting in an eight-lump model with eight reactions. In addition, changes in the activity of the catalyst during one experiment was accounted for by using two exponential activity functions, one for catalytic cracking reactions and the other for coke formation. The formation of dry gas was considered to be the product of a thermal reaction only. The kinetic parameters of the Arrhenius' law and the deactivation parameters were estimated by a non-linear regression program. In the five-lump model 12 parameters and in the eight-lump model 18 parameters (rate coefficients, activation energies and deactivation parameters) were obtained. The kinetic parameters of the Arrhenius' law were statistically

  2. Life and death of a single catalytic cracking particle

    NARCIS (Netherlands)

    Meirer, Florian; Kalirai, Samanbir; Morris, Darius; Soparawalla, Santosh; Liu, Yijin; Mesu, Gerbrand; Andrews, Joy C; Weckhuysen, Bert M

    2015-01-01

    Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for

  3. Study on Application of Bi-directional Combination Technology Integrating Residue Hydrotreating with Catalytic Cracking RICP

    Institute of Scientific and Technical Information of China (English)

    Niu Chuanfeng; Gao Yongcan; Dai Lishun; Li Dadong

    2008-01-01

    After analysing the disadvantages of the traditional residue hydrotreating-catalytic cracking combination process, RIPP has proposed a bi-directional combination technology integrating residue hydrotreating with catalytic cracking called RICP which does not further recycles the FCC heavy cycle oil (HCO) inside the FCC unit and delivers HCO to the residue hydrotreating unit as a diluting oil for the residue that is concurrently subjected to hydrotreating prior to being used as the FCC feed oil. The RICP technology can stimulate residue hydrotreating reactions through utilization of HCO along with an increased yield of FCC light distillate, resulting in enhanced petroleum utilization and economic benefits of the refinery.

  4. APPLICATION OF WET TYPE SMOKE DESULFURIZATION DEDUSTING TECHNOLOGY IN TMP CATALYTIC AND CRACKING UNIT%湿式烟气脱硫除尘技术在TMP催化裂化装置的应用

    Institute of Scientific and Technical Information of China (English)

    高传成; 马传波; 王付印

    2014-01-01

    A new smoke desulfurization dedusting unit by adopting sodium magnesium wet type desulfurization technology was built on 0.3 Mt/a TMP catalytic and cracking plant of Hengyuan Petrochemical Company .The industrial running results showed that the new built des-ulfurization dedusting unit had good operational flexibility and economic stability .Minimum con-tent of SO2 in the purified smoke could reach 3 mg/m3 and the removal rate was 99.9%.The av-erage dust content of the purified smoke was 16.3 mg/m3 and preceded the design value .Each control index on the discharged exhaust gas of the TMP catalytic and cracking unit after reforma-tion met the discharge standard requirement , which realized high efficient and continuous run-ning.%恒源石化在0.3 Mt/a的 TMP 催化裂化装置采用钠镁法湿式烟气脱硫技术,新建1套烟气脱硫除尘装置。工业运行结果表明,钠镁法烟气脱硫除尘装置具有良好的操作弹性,运行经济可靠。净化后烟气中的SO2浓度最低能达到3 mg/m3,SO2脱除率达到99.9%,净化烟气平均粉尘含量16.3 mg/m3,优于设计值。实现了高效连续运行,可控外排废气中的各项指标满足排放要求。

  5. Catalytic cracking process employing an acid-reacted metakaolin catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lussier, R.J.

    1990-07-10

    This patent describes a method for cracking hydrocarbons. It comprises: reacting a hydrocarbon feedstock under catalytic cracking conditions with a catalyst which comprises an acid reacted metakaolin composition having a mole composition of about 0.8 to 1.0 Al{sub 2}O{sub 3}.2 SiO{sub 2} and characterized by a surface area of above bout 150 m{sup 2}/g.

  6. Biofuel production from catalytic cracking of woody oils.

    Science.gov (United States)

    Xu, Junming; Jiang, Jianchun; Chen, Jie; Sun, Yunjuan

    2010-07-01

    The catalytic cracking reactions of several kinds of woody oils have been studied. The products were analyzed by GC-MS and FTIR and show the formation of olefins, paraffins and carboxylic acids. Several kinds of catalysts were compared. It was found that the fraction distribution of product was modified by using base catalysts such as CaO. The products from woody oils showed good cold flow properties compared with diesel used in China. The results presented in this work have shown that the catalytic cracking of woody oils generates fuels that have physical and chemical properties comparable to those specified for petroleum based fuels. PMID:20206508

  7. Study on Catalytic Cracking of VGO Derived from Kazakhstan-Russian Mixed Crude

    Institute of Scientific and Technical Information of China (English)

    Duan Yongsheng; Dong Yuancheng; Wei Gangling; Wang Jian

    2006-01-01

    The study on options for catalytic cracking of VGO derived from the Kazakhstan-Russian mixed crude was carried out in a small-scale riser FCC unit. The influence of several catalysts and the LCC-A additive for increasing propylene yield on the distribution and quality of FCC products was analyzed. This article sets forth the possible issues arising from processing the Kazakhstan-Russian mixed crude in FCC unit and the response measures to be adopted.

  8. Database implementation to fluidized cracking catalytic-FCC process

    International Nuclear Information System (INIS)

    A process of Fluidized Cracking Catalytic (FCC) was developed by our research group. A cold model FCC unit, in laboratory scale, was used for obtaining of the data relative to the following parameters: air flow, system pressure, riser inlet pressure, rise outlet pressure, pressure drop in the riser, motor speed of catalyst injection and density. The measured of the density is made by gamma ray transmission. For the fact of the process of FCC not to have a database until then, the present work supplied this deficiency with the implementation of a database in connection with the Matlab software. The data from the FCC unit (laboratory model) are obtained as spreadsheet of the MS-Excel software. These spreadsheets were treated before importing them as database tables. The application of the process of normalization of database and the analysis done with the MS-Access in these spreadsheets treated revealed the need of an only relation (table) for to represent the database. The Database Manager System (DBMS) chosen has been the MS-Access by to satisfy our flow of data. The next step was the creation of the database, being built the table of data, the action query, selection query and the macro for to import data from the unit FCC in study. Also an interface between the application 'Database Toolbox' (Matlab2008a) and the database was created. This was obtained through the drivers ODBC (Open Data Base Connectivity). This interface allows the manipulation of the database by the users operating in the Matlab. (author)

  9. Life and death of a single catalytic cracking particle.

    Science.gov (United States)

    Meirer, Florian; Kalirai, Sam; Morris, Darius; Soparawalla, Santosh; Liu, Yijin; Mesu, Gerbrand; Andrews, Joy C; Weckhuysen, Bert M

    2015-04-01

    Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for example, gasoline). In this process, metal deposition and intrusion is a major cause for irreversible catalyst deactivation and shifts in product distribution. We used x-ray nanotomography of industrial FCC particles at differing degrees of deactivation to quantify changes in single-particle macroporosity and pore connectivity, correlated to iron and nickel deposition. Our study reveals that these metals are incorporated almost exclusively in near-surface regions, severely limiting macropore accessibility as metal concentrations increase. Because macropore channels are "highways" of the pore network, blocking them prevents feedstock molecules from reaching the catalytically active domains. Consequently, metal deposition reduces conversion with time on stream because the internal pore volume, although itself unobstructed, becomes largely inaccessible. PMID:26601160

  10. 催化装置催化剂跑损诊断和处理%Diagnosis and treatment of the runoff of the catalysts in catalytic cracking unit

    Institute of Scientific and Technical Information of China (English)

    滕升光

    2015-01-01

    It is very important to find out the cause and location of the catalyst loss in the catalytic devices and to reduce and avoid the catalyst loss. The cause of catalyst performance,including catalyst particle size distribution,mechanical strength,heavy metal pollution capacity,and hydrothermal stability were analyzed. At the same time,the reasons for the composition changes of raw materials and improper operations were also introduced. The results showed that the problems of recycling system,fluid distribu-tion,device inherently fail and equipment abnormity were the main factors of causing the catalyst consumption. Simultaneously,the position of the catalyst loss was determined by analyzing the particle size distribution of fresh agent,spent agents,and recycling agents as well as the oil slurry solid contents and the numerical value of catalytic device in catalytic devices. The main measures of reducing and preventing the runoff of the catalysts were put forward.%找到催化剂跑损的原因和位置,减少和避免催化剂跑损,对催化装置的良好运行十分重要。分析了催化剂粒径分布、机械强度、重金属污染能力、水热稳定性等催化剂自身原因以及原料组成变化、生产操作不当等操作原因。结果表明,回收系统问题、流化分布问题、设备固有问题、设备出现异常等设备问题是造成催化剂跑损的主要因素。通过分析新鲜催化剂、待生催化剂、再生催化剂、三旋回收催化剂等筛分组成以及油浆固含量和催化装置仪表的数值诊断出催化剂跑损位置,提出减少和避免催化剂跑损的主要措施。

  11. Catalytic Cracking of Palm Oil Over Zeolite Catalysts: Statistical Approach

    Directory of Open Access Journals (Sweden)

    F. A. A. Twaiq and S. Bhatia

    2012-08-01

    Full Text Available The catalytic cracking of palm oil was conducted in a fixed bed micro-reactor over HZSM-5, zeolite ? and ultrastable Y (USY zeolite catalysts. The objective of the present investigation was to study the effect of cracking reaction variables such as temperature, weight hourly space velocity, catalyst pore size and type of palm oil feed of different molecular weight on the conversion, yield of hydrocarbons in gasoline boiling range and BTX aromatics in the organic liquid product.  Statistical Design of Experiment (DOE with 24 full factorial design was used in experimentation at the first stage.  The nonlinear model and Response Surface Methodology (RSM were utilized in the second stage of experimentation to obtain the optimum values of the variables for maximum yields of hydrocarbons in gasoline boiling range and aromatics.  The HZSM-5 showed the best performance amongst the three catalysts tested.  At 623 K and WHSV of 1 h-1, the highest experimental yields of gasoline and aromatics were 28.3 wt.% and 27 wt.%, respectively over the HZSM-5 catalyst.  For the same catalyst, the statistical model predicted that the optimum yield of gasoline was 28.1 wt.% at WHSV of 1.75 h-1 and 623 K.  The predicted optimum yield of gasoline was 25.5 wt.% at 623 K and WHSV of 1 h-1.KEY WORDS: Catalytic Cracking, Palm Oil, Zeolite, Design Of Experiment, Response Surface Methodology.

  12. CFD SIMULATION OF FLUID CATALYTIC CRACKING IN DOWNER REACTORS

    Institute of Scientific and Technical Information of China (English)

    Fei; Liu; Fei; Wei; Yu; Zheng; Yong; Jin

    2006-01-01

    A mathematical model has been developed for the simulation of gas-particle flow and fluid catalytic cracking in downer reactors. The model takes into account both cracking reaction and flow behavior through a four-lump reaction kinetics coupled with two-phase turbulent flow. The prediction results show that the relatively large change of gas velocity affects directly the axial distribution of solids velocity and void fraction, which significantly interact with the chemical reaction. Furthermore, model simulations are carried out to determine the effects of such parameters on product yields, as bed diameter, reaction temperature and the ratio of catalyst to oil, which are helpful for optimizing the yields of desired products. The model equations are coded and solved on CFX4.4.

  13. WELD CRACK RECTIFICATION IN CATALYTIC CONVERTER BY FABRICATION OF CUSTOMIZED JIG PLATES

    OpenAIRE

    A. Vignesh; P. Kritin Ram

    2015-01-01

    The main objective of this paper is to “rectify the weld cracks by the fabrication of customized jig plates”. In the engine section of the industry, there were frequent rejections of the catalytic converters due to weld cracks. When the catalytic converter assembly line was inspected, tiny cracks in the weld were found vi sually. Then they were tested through bench magnifiers and dye penetration test for confirmation and it was confirmed to have cracks in ...

  14. Gamma-ray application to the measurement of a media distribution at the catayst cooler of a residue fluid catalytic cracking unit (RFCCU) in the petrochemical industry

    International Nuclear Information System (INIS)

    The dynamic behavior of the process media in the petrochemical industry can hardly be observed during its operation. Because the information on the process media is directly related to the processes efficiency, therefore it is necessary to establish what is actually happening inside the process unit. For this purpose, a field experiment was performed to study the fluidized catalyst patterns and confirm the internal conditions by using a sealed gamma-ray source. From the results, the areas showing a different pattern from the surrounding vicinity were found successfully. Especially at the upper part of the connection point at which the pipeline from are generator was joined, a relatively low amount of catalyst was distributed. Sealed gamma-ray application to the catalyst cooler is considered as a worthwhile technique for a measurement of the catalyst distribution at the RFCCU.

  15. High-pressure catalytic and thermal cracking of polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Mosio-Mosiewski, Jan; Warzala, Marek; Morawski, Ireneusz; Dobrzanski, Tadeusz [Institute of Heavy Organic Synthesis, ul. Energetykow 9, 47-225 Kedzierzyn-Kozle (Poland)

    2007-04-15

    The thermal cracking and catalytic cracking processes of low-density polyethylene were studied in a closed autoclave. The compositions of gaseous and liquid products were analysed by means of GC/FID and GS/MS chromatographic methods. The fractional composition of liquid products was found by distillation. Increased temperature of PE depolymerisation process increases the production of gaseous products and low-boiling liquid compounds; more aromatic hydrocarbons are formed instead of alkenes. When a lower temperature and longer time are adopted for the process to reach the assumed conversion, more straight chained hydrocarbons are produced. The acidic aluminosilicate catalyst yields more low-boiling liquid fractions, more isoalkanes and more aromatics. The neutral alumina is favourable for the production of alkenes and vacuum gas oil fraction in comparison to a non-catalytic process. The Ni-Mo/Al{sub 2}O{sub 3} catalyst is efficient in hydrogenation of depolymerisation products. The reaction products contain only saturated compounds then and no aromatics are formed. (author)

  16. Pregnant crack addicts in a psychiatric unit

    Directory of Open Access Journals (Sweden)

    Gabriela de Moraes Costa

    2012-01-01

    Full Text Available OBJECTIVE: In this study we aim to characterize a sample of 85 pregnant crack addicts admitted for detoxification in a psychiatric inpatient unit. METHOD: Cross-sectional study. Sociodemographic, clinical, obstetric and lifestyle information were evaluated. RESULTS: Age of onset for crack use varied from 11 to 35 years (median = 21. Approximately 25% of the patients smoked more than 20 crack rocks in a typical day of use (median = 10; min-max = 1-100. Tobacco (89.4%, alcohol (63.5% and marijuana (51.8% were the drugs other than crack most currently used. Robbery was reported by 32 patients (41.2%, imprisonment experience by 21 (24.7%, trade of sex for money/drugs by 38 (44.7%, home desertion by 33 (38.8%; 15.3% were positive for HIV, 5.9% for HCV, 1.2% for HBV and 8.2% for syphilis. After discharge from the psychiatric unit, only 25% of the sample followed the proposed treatment in the chemical dependency outpatient service. CONCLUSION: Greater risky behaviors for STD, as well as high rates of maternal HIV and Syphilis were found. Moreover, the high rates of concurrent use of other drugs and involvement in illegal activities contribute to show their chaotic lifestyles. Prevention and intervention programs need to be developed to address the multifactorial nature of this problem.

  17. Catalytic cracking of endothermic fuels in coated tube reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by means of X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM).The coating thickness is 10-20 μm and the particle size of the zeolites is in the range of 1-5 μm.In the coated reactor,cracking of endothermic fuels including n-dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600℃ and 625℃ to investigate their heat sinks and conversion of catalytic reactions.For the reaction catalyzed by HY (25% mass fraction) coating,the heat sink capacity of ndodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600℃ and at 625℃,respectively.Conversion of n-dodecane also increases from 42% to 60% at 600℃ and from 66% to 80% at 625℃.The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.

  18. Effect of Metal Contamination on the Performance of Catalyst for Deep Catalytic Cracking Process

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhigang

    2009-01-01

    The effect of different metal contamination levels of catalysts for Deep Catalytic Cracking (DCC) on the distribu-tion and selectivity of DCC products was investigated in a FCC pilot unit. The pilot test results showed that the effects of the metal contamination level of catalyst on the propylene yield, the coke yield, the LPG yield, the gasoline yield, the selectivity of low carbon olefins, and coke selectivity was significant, and that the influence of metal contamination level on the conversion and dry gas yield was minor.

  19. Condiciones Extremas de Operación en Unidades de Desintegración Catalítica y Multiplicidad de Estados Estacionarios Severe Operating Conditions in Catalytic Cracking Units and Multiplicity of Steady-States

    Directory of Open Access Journals (Sweden)

    José R Hernández-Barajas

    2007-01-01

    Full Text Available Se ha estudiado y analizado las condiciones extremas de operación en unidades de desintegración catalítica y su efecto en la multiplicidad de estados estacionarios. El modelo propuesto está basado en ecuaciones de conservación de materia y energía y ha permitido demostrar que, para ambos modos de combustión, parcial y total, existen entre uno y cinco estados estacionarios. La multiplicidad más común ocurre cuando existen tres estados estacionarios que se presentan a condiciones típicas de operación. La existencia de un solo estado estacionario es producida por una disminución abrupta en la eficiencia de la fluidización y distribución del aire en el regenerador. Se han determinado los dominios de atracción y las trayectorias dinámicas de cada estado estacionario en ese escenario y se sugiere que se debe tomar en consideración este fenómeno en el diseño de una estrategia de control robusto. Finalmente, se muestra que la existencia de cinco estados estacionarios está relacionada con una disminución de la velocidad de oxidación heterogénea del monóxido de carbonoThis paper studies an analyzes the effect of severe operating conditions in catalytic cracking units on multiplicity of steady-states. The model proposed here is based on mass and energy conservative equations and has been able to demonstrate the existence of one to five steady states for both partial and complete combustion regimes. The most common multiplicity is the existence of three steady states that occurs at typical operating conditions. The existence of a unique steady state is produced by an abrupt decrease in both fluidization effectiveness and air distribution inside the regenerator. Attraction domains and dynamic trajectories of each steady state have been determined for this scenario and is suggested that this phenomenon must be taken into account in the design of a robust control strategy. Finally, it is shown that the existence of five steady states is

  20. The Investigation of Reducing PAHs Emission from Coal Pyrolysis by Gaseous Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Yulong Wang

    2014-01-01

    Full Text Available The catalytic cracking method of PAHs for the pyrolysis gaseous products is proposed to control their pollution to the environment. In this study, the Py-GC-MS is used to investigate in situ the catalytic effect of CaO and Fe2O3 on the 16 PAHs from Pingshuo coal pyrolysis under different catalytic temperatures and catalyst particle sizes. The results demonstrate that Fe2O3 is effective than that of CaO for catalytic cracking of 16 PAHs and that their catalytic temperature corresponding to the maximum PAHs cracking rates is different. The PAHs cracking rate is up to 60.59% for Fe2O3 at 600°C and is 52.88% at 700°C for CaO. The catalytic temperature and particle size of the catalysts have a significant effect on PAHs cracking rate and CaO will lose the capability of decreasing 16 PAHs when the temperature is higher than 900°C. The possible cracking process of 16 PAHs is deduced by elaborately analyzing the cracking effect of the two catalysts on 16 different species of PAHs.

  1. Research and Development of Novel Heavy Oil Catalytic Cracking Catalyst RCC-1

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiexiao; Zhou Yan; Xu Yun; Tian Huiping

    2014-01-01

    A novel heavy oil catalytic cracking catalyst RCC-1 was developed by using the ultra-stable zeolite, which was hydrothermally treated and modiifed through cleaning its pores to serve as the active component. The chemical composi-tion and physicochemical properties of RCC-1 catalyst were studied by XRF, BET, pore volume analysis, attrition index analysis, and particle size distribution determination methods, and its catalytic cracking performance was also evaluated by a microreactor for light oil cracking and the ACE device. The test results showed that the new type of heavy oil catalytic cracking catalyst RCC-1 had good physicochemical properties and heavy oil cracking ability, strong anti-metallic contami-nation capability, good product distribution, good coke selectivity and gasoline selectivity, and excellent reduction of gaso-line oleifn content characteristics.

  2. Seleção de concretos refratários densos antierosivos para unidades de craqueamento catalítico fluidizado de petróleo Selection of dense antierosive refractory castables for fluid catalytic cracking units

    Directory of Open Access Journals (Sweden)

    F. A. S. Serra

    2012-03-01

    Full Text Available Na indústria petroquímica a unidade de craqueamento catalítico fluidizado de petróleo é um importante equipamento para aplicação de concretos refratários devido à necessidade de se obter produtos especializados. Normalmente, a seleção destes materiais é baseada na análise química e em medidas de densidade aparente, resistência mecânica por compressão uniaxial e erosimetria a frio. Para avaliação dos requisitos de seleção usuais, cinco concretos de alta alumina, sendo três de baixo teor de cimento e dois convencionais de uso comercial, foram avaliados por resistência à compressão e erosimetria a frio. Testes complementares que atualmente não são utilizados no processo de seleção também foram realizados, tais como: resistência ao choque térmico, módulo de ruptura a quente e exposição em atmosfera de CO. A análise mostrou que as especificações vigentes são baseadas principalmente na experiência com a utilização de produtos não originalmente projetados para esta aplicação e que o desenvolvimento de produtos mais adequados é inibido pelas restrições das especificações atuais. Também se verificou que a seleção é limitada pela falta de ensaios que avaliem o desempenho em condições mais próximas das de uso. Neste sentido, o teste de resistência à deposição de carbono pela exposição em atmosfera de CO mostrou-se interessante por contribuir para uma melhor seleção dos concretos refratários densos antierosivos.In the petrochemical industry the fluidized catalytic cracking unit is an important vessel for refractory castables application due the necessity of obtaining specialized products. Usually, the selection of these materials is based on the chemical analysis, apparent density, cold crushing strength and cold erosion test. For the evaluation of the present selection requirements, five high-alumina castables, being three of low cement and two conventional of commercial use, were

  3. A Technical and Economical Evaluation of CO2 Capture from Fluidized Catalytic Cracking (FCC Flue Gas

    Directory of Open Access Journals (Sweden)

    Digne Romina

    2014-11-01

    Full Text Available Environmental issues, related to greenhouse gas and among them CO2, are becoming short term challenges. Pressure on industries and therefore on refining to limit and manage CO2 emissions will be reinforced in next few years. Refining industry is responsible for about 2.7% of global CO2 emissions. Fluidized Catalytic Cracking unit (FCC, one of the main process in refining, represents by itself 20% of the refinery CO2 emissions. As FCC unit is present in half of the refining schemes, it is challenging to find technologies to manage its emissions. Based on an industrial case, the aims of the presented work are to determine if amine technology HiCapt+, developed for power plant, might be a relevant solution to manage FCC CO2 emissions and to evaluate the additional cost to be supported by refiners.

  4. Catalytic Performance of Bare Supporters and Supported KVO3 Catalysts for Cracking n-Butane to Produce Light Olefins

    Institute of Scientific and Technical Information of China (English)

    LuJiangyin; ZhaoZhen; XuChunming; ZhangPu

    2005-01-01

    Supported KVO3 catalysts were prepared by impregnating different kinds of.supporters (α-Al2O3,γ-Al2O3 and SiO2 powders) with a KVO3 solution. The activity of the bare supporters and supported catalysts were evaluated in a continuous micro-reactivity test unit, with n-butane as a raw material. The results show that KVO3 has no catalytic activity, but it can increase the selectivity to light olefins. The supporter of γ-Al2O3 has good catalytic performance for nbutane cracking when the reaction temperature is below 700℃.

  5. Skeletal Isomerization and Inter-molecular Hydrogen Transfer Reactions in Catalytic Cracking

    Institute of Scientific and Technical Information of China (English)

    Gao Yongcan; Zhang Jiushun; Xie Chaogang; Long Jun

    2002-01-01

    Bimolecular hydrogen transfer and skeletal isomerization are the important secondary reac tions among catalytic cracking reactions, which affect product yield distribution and product quality.Catalyst properties and operating parameters have great impact on bimolecular hydrogen transfer and skeletal isomerization reactions. Bimolecular hydrogen transfer activity and skeletal isomerization activity of USY-containing catalysts are higher than that of ZSM-5-containing catalyst. Coke deposition on the active sites of catalyst may suppress bimolecular hydrogen transfer activity and skeletal isomerization activity of catalyst in different degrees. Short reaction time causes a decrease of hydrogen trans fer reaction, but an increase of skeletal isomerization reaction compared to cracking reaction in catalytic cracking process.

  6. Catalytic pyrolysis of atmospheric residue on a fluid catalytic cracking catalyst for the production of light olefins

    Institute of Scientific and Technical Information of China (English)

    YANG Lian-guo; MENG Xiang-hai; XU Chun-ming; GAO Jin-sen; LIU Zhi-chang

    2009-01-01

    Catalytic pyrolysis of Chinese Daqing atmospheric residue on a commercial fluid catalytic cracking (FCC) catalyst was investigated in a confined fluidized bed reactor. The results show that the commercial FCC catalyst has good capability of cracking atmospheric residue to light olefins. The analysis of gas samples shows that the content of total light olefins in cracked gas is above 80%. The analysis of liquid samples shows that the content of aromatics in liquid samples ranges from 60% to 80%, and it increases with the enhancement of reaction temperature. The yield of total light olefins shows a maximum with the increase of reaction temperature, the weight ratios of catalyst-to-oil and steam-to-oil, respectively. The optimal reaction temperature, the weight ratios of catalyst-to-oil and steam-to-oil are about 650℃, 15 and 0.75, respectively.

  7. Catalytic ramifications of steam deactivation of Y zeolites: An analysis using 2-methylhexane cracking

    Energy Technology Data Exchange (ETDEWEB)

    Yaluris, G.; Dumesic, J.A. [Univ. of Wisconsin, Madison, WI (United States); Madon, R.J. [Engelhard Corp., Iselin, NJ (United States)

    1999-08-15

    Kinetic analysis of experimental data for 2-methylhexane cracking demonstrates that trends in activity and selectivity are well simulated by adjusting a single parameter that represents the acid strength of a Y-based FCC catalyst. This acid strength may be modified via steam deactivation, and the authors have experimentally corroborated acidity changes using ammonia microcalorimetry and infrared spectroscopy. Increased severity of steam treatment reduces the number and strength of catalyst acid sites, and it leads to a reduction in the turnover frequency of all surface processes and a decrease in overall site time yield. Streaming of the catalyst does not change the fundamental chemistry involved in catalytic cracking. However, change in acidity caused by steaming alters product selectivity by changing relative rates of various catalytic cycles in the cracking process. For example, steam treatment increases olefin selectivity by favoring catalytic cycles that produce olefins.

  8. FAILURE ANALYSIS AND INSPECTION OF CRACKING OF IN-SERVICE CATALYTIC REGENERATOR

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The special subject"research on life prediction technology of important in-service pressure vessels" mainly analyzes the failure mechanism of large-sized important and critical in-service pressure vessels under the action of working medium and investigates safety assessment and life prediction technology with a view to enhance the operation reliability of in-service pressure vessels in China. Based on a series of accident investigation and test & measuring research, the cause of cracking of catalytic regenerator is analyzed and the in-line non-destructive examination method and failure prevention measures for the cracking of catalytic regenerator are proposed.

  9. Kinetic and catalytic performance of a BI-porous composite material in catalytic cracking and isomerisation reactions

    KAUST Repository

    Al-Khattaf, S.

    2012-01-10

    Catalytic behaviour of pure zeolite ZSM-5 and a bi-porous composite material (BCM) were investigated in transformation of m-xylene, while zeolite HY and the bi-porous composite were used in the cracking of 1,3,5-triisopropylbenzene (TIPB). The micro/mesoporous material was used to understand the effect of the presence of mesopores on these reactions. Various characterisation techniques, that is, XRD, SEM, TGA, FT-IR and nitrogen sorption measurements were applied for complete characterisation of the catalysts. Catalytic tests using CREC riser simulator showed that the micro/mesoporous composite catalyst exhibited higher catalytic activity as compared with the conventional microporous ZSM-5 and HY zeolite for transformation of m-xylene and for the catalytic cracking of TIPB, respectively. The outstanding catalytic reactivity of m-xylene and TIPB molecules were mainly attributed to the easier access of active sites provided by the mesopores. Apparent activation energies for the disappearance of m-xylene and TIPB over all catalysts were found to decrease in the order: EBCM>EZSM-5 and EBCM>EHY, respectively. © 2012 Canadian Society for Chemical Engineering.

  10. Catalytic cracking process exploying a zeolite as catalysts and catalyst supports

    Energy Technology Data Exchange (ETDEWEB)

    Lussier, R.J.; Surland, G.J.

    1989-06-06

    This patent describes a method for cracking hydrocarbons which comprises reacting a hydrocarbon feedstock under catalytic cracking conditions in the presence of a cracking catalyst composition which comprises a crystalline zeolite, an inorganic oxide matrix, and a finely divided, calcined caustic leached aluminum silicon spinel/mullite component having a silica to alumina mole ratio of from about 0.5 to 1.7 and an acid site retention of from about 70 to 95 percent after treating at 1350{sup 0}F in the presence of saturated steam and a X-ray diffraction pattern as set forth in Tables A or B.

  11. Oxidative cracking of n-Hexane : a catalytic pathway to olefins

    NARCIS (Netherlands)

    Boyadjian, Cassia

    2010-01-01

    Steam cracking, the major, current existing route for light olefin production, is the most energy consuming process in the chemical industry. The need for an energy efficient processes, urged substantial research work for the development of new catalytic technologies for light olefin production. Ste

  12. Effect of ultralow thermal neutron flow on catalytic cracking of n-hexane

    International Nuclear Information System (INIS)

    Effect of ultraweak thermal neutron fluxes on proceeding of heterogenous catalytic reaction of n-hexane cracking is studied. It is established that thermal neutron flux through the catalyst results either in significant growth of reaction rate, while temperature is constant in the reactor, or in temperature decrease in reactor at fixed heat supply to it. (author)

  13. Thermodynamic analysis of a process for producing high-octane gasoline components from catalytic cracking gas

    Science.gov (United States)

    Ismailova, Z. R.; Pirieva, Kh. B.; Kasimov, A. A.; Dzhamalova, S. A.; Gadzhizade, S. M.; Nuriev, Sh. A.; Zeinalova, S. Kh.; Dzhafarov, R. P.

    2016-03-01

    The results from a thermodynamic analysis of high-octane gasoline component production from catalytic cracking gases using zeolite catalyst OMNIKAT-210P modified with Ni, Co, Cr are presented. The equilibrium constants of the reactions assumed to occur in this process are calculated, along with the equilibrium yield of the reactions.

  14. Development and Commercial Application of a Novel Catalyst DVR-1 for Catalytic Cracking of Daqing Vacuum Residue

    Institute of Scientific and Technical Information of China (English)

    Yang Yinan; Tian Huiping; Chen Yun; Wang Yamin

    2002-01-01

    A newly developed catalyst type DVR- 1 for catalytic cracking of Daqing vacuum resid was put into use in a commercial VRFCC unit. This catalyst features uniquely active matrix and modified ultrastable zeolite. The commercial application results show that the DVR-1 type catalyst has the advantage of high heavy oil conversion, good metal tolerance and good stability for catalyst regeneration. The FCC tests have shown favorable product distribution, acceptable product quality and enormous economic benefits when processing the feedstock containing 75%-100% Daqing VR.

  15. Catalytic Cracking of Triglyceride-Rich Biomass toward Lower Olefins over a Nano-ZSM-5/SBA-15 Analog Composite

    Directory of Open Access Journals (Sweden)

    Xuan Hoan Vu

    2015-10-01

    Full Text Available The catalytic cracking of triglyceride-rich biomass toward C2–C4 olefins was evaluated over a hierarchically textured nano-ZSM-5/SBA-15 analog composite (ZSC-24 under fluid catalytic cracking (FCC conditions. The experiments were performed on a fully automated Single-Receiver Short-Contact-Time Microactivity Test unit (SR-SCT-MAT, Grace Davison at 550 °C and different catalyst-to-oil mass ratios (0–1.2 g∙g−1. The ZSC-24 catalyst is very effective for transformation of triglycerides to valuable hydrocarbons, particularly lower olefins. The selectivity to C2–C4 olefins is remarkably high (>90% throughout the investigated catalyst-to-oil ratio range. The superior catalytic performance of the ZSC-24 catalyst can be attributed to the combination of its medium acid site amount and improved molecular transport provided by the bimodal pore system, which effectively suppresses the secondary reactions of primarily formed lower olefins.

  16. High activity in catalytic cracking of large molecules over micro-mesoporous silicoaluminophosphate with controlled morphology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel micro-mesoporous silicoaluminophosphate(MUS-5) with controlled morphology has been first synthesized in a two-step route.The physical properties of the silicoaluminophosphate were characterized using XRD,SEM,TEM,nitrogen adsorption-desorption and NH3-TPD techniques.When the pH value of the solution system was varied in the range from 2.0 to 5.0,three different morphologies of silicoaluminophosphate including chain-like,flower-like and barrel-like morphology were obtained.Catalytic tests showed that the silicoaluminophosphate exhibited higher catalytic activity compared with the conventional microporous SAPO-5 under the same conditions for catalytic cracking of 1,3,5-triisopropylbenzene heavy aromatics.The remarkable catalytic reactivity was mainly attributed to the presence of the hierarchical porosity in the silicoaluminophosphate catalyst.

  17. Corrosion resistance of a steel under an oxidizing atmosphere in a fluid catalytic cracking regenerator

    Energy Technology Data Exchange (ETDEWEB)

    Caminha, Ieda [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil). Lab. de Metalografia e de Dureza; Zeng, Chaoliu [Chinese Academy of Science, Shenyang (China). Inst. of Corrosion and Protection of Metals. State Key Lab. for Corrosion and Protection; Paes, Marcelo Piza [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Monteiro, Mauricio Jesus; Rizzo, Fernando [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Ciencia dos Materiais e Metalurgia]. E-mail: rizzo@dcmm.puc-rio.br

    2004-03-01

    In the present work, the corrosion resistance of an ASTM A 387 G11 steel was evaluated under two conditions: an oxidizing atmosphere in a fluid catalytic cracking regenerator of a petroleum processing unit and a simulated atmosphere in the laboratory, at temperatures of 650 deg C and 700 deg C. The characterization of the phases present in the oxidized layer was carried out by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) with X-ray energy dispersive analysis (EDS). Severe corrosion was observed after exposure to both the real and simulated conditions, with formation of several iron oxides (Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} and Fe O) in the product scale layer, as well as a slight inner oxidation and sulfidation of chromium in the substrate. Internal nitridation of the silicon and the manganese was observed only in the real condition, probably related to the long-term exposure inside the regenerator. (author)

  18. Development of new deactivation method for simulation of fluid catalytic cracking equilibrium catalyst

    Indian Academy of Sciences (India)

    T Chiranjeevi; D T Gokak; V Ravikumar; P S Viswanathan

    2014-03-01

    Selection of a good catalyst is the easiest way to increase profitability of a fluid catalytic cracking (FCC) unit. During operation, these catalysts get deactivated due to operation at high temperatures, steam and deposition of metals on the catalyst. Developing a proper catalyst deactivation method is crucial for optimization of a good catalyst for FCC. Conventional laboratory deactivation procedures include direct metal impregnation method, cyclic deactivation method (CDM) and cyclic propylene steaming (CPS). Direct metal impregnation method gives higher coke and gas yields. CDM and CPS methods implementation is very difficult and time-consuming and there is a deviation in coke and gas yield. New rapid deactivation method has been developed to simulate plant equilibrium catalyst (E-Cat) by modifying metal impregnation, steaming and oxidation/reduction procedures. The E-Cat generated through a new deactivation method was characterized for physico-chemical properties using X ray diffraction (XRD), temperature-programmed reduction (TPR), and SEM-EDX and activity studies. XRD studies show that metals are dispersed well on catalyst samples. SEMEDX studies reveal that the morphology of simulated E-Cat and plant E-Cat catalyst particles appear to be same. E-Cat obtained by new deactivationmethod gives better coke and gas yields. Two E-Cats were also generated through CDM and direct metal impregnation method for comparing with the one generated through new method. New deactivation method also significantly reduces the evaluation time.

  19. PEMBUATAN BIODIESEL DARI MINYAK GORENG BEKAS DENGAN PROSES CATALYTIC CRACKING

    Directory of Open Access Journals (Sweden)

    Luqman Buchori

    2012-02-01

    Full Text Available Crude oil is a source of energy which is not be renewable. This fact motivates so much countries ineconomizing on fuel. Many researches have been done to gets another fuel substitute the crude oil.Biodiesel is represented as fuel instead of diesel fuel, and it is produced from vegetable oil. In the otherside, ex-cooking oil is waste-product from food industry, restaurant and household which is potential tobe alternative fuels because of the high contents of carbon and hydrogen atoms. Commonly the biodieselmade from vegetable oil by esterification and transesterification process. But if using esterification andtransesterification process to ex-cooking oil material, it is not economically feasible because the processmakes another reaction between alkaly catalist and oil to produce soap. One of biodiesel process iscatalytic cracking of the ex-cooking oil. This research is aimed to analyze zeolite catalist size effect(0.125mm; 0.3375mm; 0.425mm; 0.85mm; 1.18mm, and acid concentration on the product (2N; 3N;4N. This result shows that at 4N acid concentration and 0.125 mm zeolite catalist size is optimal whichcan reach diesel specification.

  20. Catalytic cracking process employing an aluminum silicon spinel-mullite-gamma alumina containing catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lussier, R.J.

    1990-01-16

    This patent describes a method for catalytically cracking hydrocarbons. It comprises reacting a hydrocarbon feedstock with a catalytic composition comprising an aluminum silicon spinel-mellite-gamma alumina bound composite in which the spinel phase has a silica to alumina ratio of above about 0.40 and characterized by a surface area of from about 100 to 300 m2/g, a total pore volume of from about 0.30 to 0.70 cc/g, the x-ray pattern set forth in Table B,and an alkali-metal oxide content of below about 0.50 weight percent.

  1. Catalytic cracking of fatty oils and fatty acids. A novel route towards bio-jet fuel

    Energy Technology Data Exchange (ETDEWEB)

    Heil, Volker; Kraft, Axel; Menne, Andreas; Unger, Christoph A. [Fraunhofer-Institut fuer Umwelt-, Sicherheits- und Energietechnik UMSICHT, Oberhausen (Germany)

    2013-06-01

    Components for bio-jet fuel production can be achieved by catalytic cracking of fatty oils and fatty acids over activated carbon catalyst. At reaction temperatures of about 450 C, mainly C15- and C16-n-Alkanes that can be isomerized for jet fuel-usage are produced. They can be used for bio-kerosene after isomerization. Introducing high-oleic feedstock like HO-sunflower-oil and slightly raising the reaction temperature leads to high amounts of n-alkanes in the jet-fuel boiling range. The process proves to be very robust concerning feedstock compositions and impurities. Therefore, catalytic cracking over activated carbon is an ideal pathway to transform not only bio-based oils, but also their wastes and fatty acid-containing by-products from plant oil processing into high-quality fuel components. Using alternative catalysts leads to an enhanced production of alkylated benzenes which are indispensable for aviation jet fuel. (orig.)

  2. Catalyst Particles for Fluid Catalytic Cracking Visualized at the Individual Particle Level by Micro-Spectroscopy

    OpenAIRE

    Buurmans, I.L.C.

    2011-01-01

    In this PhD research the investigation of the reactivity and acidity of Fluid Catalytic Cracking (FCC) catalysts at the level of an individual catalyst particles is described. A range of micro-spectroscopic techniques has been applied to visualize both the active zeolite component within the catalyst particles as well as the matrix components. The most important techniques applied were UV-Vis micro-spectroscopy, confocal fluorescence microscopy, integrated laser and electron microscopy (a com...

  3. Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

    OpenAIRE

    Toshiyuki Kimura; Chen Liu; Xiaohong Li; Takaaki Maekawa; Sachio Asaoka

    2012-01-01

    In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of m...

  4. ACIDIC REMOVAL OF METALS FROM FLUIDIZED CATALYTIC CRACKING CATALYST WASTE ASSISTED BY ELECTROKINETIC TREATMENT

    OpenAIRE

    R. B. G. Valt; A. N. Diógenes; L. S. Sanches; N. M. S. Kaminari; M. J. J. S. Ponte; H. A. Ponte

    2015-01-01

    AbstractOne of the main uses of catalysts in the oil industry is in the fluidized catalytic cracking process, which generates large quantities of waste material after use and regeneration cycles and that can be treated by the electrokinetic remediation technique, in which the contaminant metals are transported by migration. In this study, deactivated FCC catalyst was characterized before and after the electrokinetic remediation process to evaluate the amount of metal removed, and assess struc...

  5. Modelling and parameter estimation in reactive continuous mixtures: the catalytic cracking of alkanes - part II

    Directory of Open Access Journals (Sweden)

    F. C. PEIXOTO

    1999-09-01

    Full Text Available Fragmentation kinetics is employed to model a continuous reactive mixture of alkanes under catalytic cracking conditions. Standard moment analysis techniques are employed, and a dynamic system for the time evolution of moments of the mixture's dimensionless concentration distribution function (DCDF is found. The time behavior of the DCDF is recovered with successive estimations of scaled gamma distributions using the moments time data.

  6. Modelling of FCC (Fluid Catalytic Cracking) risers with six lumps; Modelo de elevadores de Unidades de Craqueamento Catalitico com cinetica de seis classes

    Energy Technology Data Exchange (ETDEWEB)

    Baldessar, Fabio; Negrao, Cezar O. Ribeiro; Palu, Claudia [Centro Federal de Educacao Tecnologica do Parana (CEFET-PR), Curitiba, PR (Brazil)

    2004-07-01

    The current work presents a mathematical model of an ascendant flow vertical reactor (riser) of a Fluid Catalytic Cracking Unit. The two-phase flow (gas-solid) and the cracking reactions are admitted one-dimensional and steady state. Mass, momentum and energy conservation equations are considered for each phase (solid and gas). A six-lump kinetic model is employed to evaluate gasoil, gasoline, GLP, fuel gas, light cycle oil and coke fractions. The model results are compared to experimental values from a pilot plant and to another model found in the literature. The results are in good agreement, showing the model has great potential. (author)

  7. Effects of Dealumination and Desilication of Beta Zeolite on Catalytic Performance in n-Hexane Cracking

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2016-01-01

    Full Text Available Catalytic cracking of n-hexane to selectively produce propylene on Beta zeolite was carried out. The H-Beta (HB (Si/Al = 77 zeolite showed higher catalytic stability and propylene selectivity than the Al-rich HB (Si/Al = 12, due to its smaller number of acid sites, especially Lewis acid sites (LAS. However, catalytic stability and propylene selectivity in high n-hexane conversions were still not satisfactory. After dealumination with HNO3 treatment, catalytic stability was improved and propylene selectivity during high n-hexane conversions was increased. On the other hand, catalytic stability was not improved after desilication with NaOH treatment, although mesopores were formed. This may be related to the partially destroyed structure. However, propylene selectivity in high n-hexane conversions was increased after alkali treatment. We successfully found that the catalytic stability was improved and the propylene selectivity in high n-hexane conversions was further increased after the NaOH treatment followed by HNO3 treatment. This is due to the decrease in the number of acid sites and the increase in mesopores which are beneficial to the diffusion of coke precursor.

  8. Study on Expansion of Steam Cracking Unit to 660 kt/a at Yanshan Petrochemical Company

    Institute of Scientific and Technical Information of China (English)

    Cao Xianghong

    2003-01-01

    Yanshan Petrochemical Company after having expanded its 300 kt/a steam cracking unit to 450 kt/a in 1994 is still experiencing such problems as low feedstock flexibility, high energy consumption and smaller scale of ethylene unit. In order to fully improve technical capability of steam crackers, reduce energy consumption, improve feedstock flexibility and increase production capacity, a lot of technical revamp cases on steam cracking were studied and compared. Revamp of relevant facilities has expanded the ethylene capacity to the target of 660 kt/a with the actual capacity reaching 710 kt/a. This revamp project has remarkably reduced the energy consumption, which is capable of using naphtha, light diesel fuel, heavy diesel fuel and the hydrocracked tail oil as the steam cracking feedstock. This project is the first to apply refrigeration by means of a mixed cooling agent and has succeeded in using C3 catalytic rectification/hydrogenation technology, which has given an impetus to the progress of steam cracking industry in the world.

  9. 一种新的生产计划与催化裂化装置过程操作集成的闭环策略%A novel close-loop strategy for Integrating Process Operations of Fluidized Catalytic Cracking Unit with Production Planning Optimization

    Institute of Scientific and Technical Information of China (English)

    王如强; 李初福; 何小荣; 陈丙珍

    2008-01-01

    Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practically feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit (FCCU), a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm (GA) coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction (FGIC) method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.

  10. Catalytic cracking of the top phase fraction of bio-oil into upgraded liquid oil

    Science.gov (United States)

    Sunarno, Rochmadi, Mulyono, Panut; Budiman, Arief

    2016-06-01

    The energy consumption is increasing, while oil reserves as a primary energy resource are decreasing, so that is the reason seeking alternative energy source is inevitable. Biomass especially oil palm empty fruit bunches (EFB) which is abundant in Indonesia can be processed into bio-oil by pyrolysis process. The potential for direct substitution of bio-oil for petroleum may be limited due to the high viscosity, high oxygen content, low heating value, and corrosiveness. Consequently, upgrading of the bio-oil before use is inevitable to give a wider variety of applications of its liquid product. Furthermore, upgrading process to improve the quality of bio-oil by reduction of oxygenates involves process such as catalytic cracking. The objective of this research is to study the effect of operation temperature on yield and composition of upgraded liquid oil and to determine physical properties. Bio-oil derived from EFB was upgraded through catalytic cracking using series tubular reactor under atmospheric pressure on a silica-alumina catalyst. Results show that increasing temperature from 450 to 600 °C, resulting in decreasing of upgraded liquid oil (ULO) yield, decreasing viscosity and density of ULO, but increasing in calorimetric value of ULO. The increasing temperature of cracking also will increase the concentration of gasoline and kerosene in ULO.

  11. Synthesis and utilization of catalytically cracked cashew nut shell liquid in a diesel engine

    KAUST Repository

    Vedharaj, S.

    2015-09-30

    In this study, CNSL (Cashew nut shell liquid), an economically viable feedstock among the other contemporary resources, has been considered as an appropriate source of alternate fuel. Herein, CNSL was extracted from cashew nut outer shell, a waste product, through a unique approach of steam treatment process followed by mechanical crushing technique. In contrast to the past studies that have attempted to use unprocessed CNSL directly as substitute for diesel, this study has resorted to use processed CNSL by cracking it using zeolite catalyst. Thus, both the extraction of CNSL from cashew nut outer shell and processing of it through catalytic cracking process to help synthesize CC-CNSL (catalytically cracked CNSL) are different, which underscores the significance of the current work. In wake of adopting such distinct methodologies with fuel characterization, the properties of CC-CNSL such as viscosity and calorific value were figured out to be improved. Subsequently, CC-CNSL20 (20% CC-CNSL and 80% diesel) was tested at different fuel injection pressure such as 200 bar, 235 bar, 270 bar and 300 bar so as to optimize its use in a single cylinder diesel engine. From the engine experimental study, CC-CNSL20 was found to evince better engine performance than diesel and the composite emissions of CO (carbon monoxide), HC (hydrocarbon), NOX (oxides of nitrogen) and smoke, computed based on ISO 8178 D2 standard test cycle, were found to be better than diesel and incompliance with the legislative norms for genset.

  12. Session 4: Improved middle distillate selectivity using pre-treated catalytic cracking catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Trimm, D.L.; Chia, D.A. [New South Wales Univ., School of Chemical Engineering and Industrial Chemistry, Sydney (Australia)

    2004-07-01

    Demand for transport fuels has led to refining practices designed to maximize yields of middle distillate. One such practice involves the addition of light hydrocarbons to the bottom of the riser of a fluid catalytic cracker. Coke, deposited on the most acidic sites of a fresh catalyst, is suggested to limit over-cracking and maximize the yield of middle distillate. Mandal et al. found optimal results with the deposition of 0.2 - 0.3 wt % coke. An attempt to explore this finding using an equilibrated catalyst was unsuccessful and, as a result, the mechanism of the reaction has been explored using squalane (C{sub 30}H{sub 62}) cracking as a test system. All catalyst testing was carried out using a standard micro-activity test unit. Squalane was injected through 0.1 - 5 g catalyst mounted in a heated reactor. Gases and liquids were analysed using gas chromatography. Industrially equilibrated catalyst was fully characterized. Significant changes in the physical and chemical properties of the original catalyst (AKZO Access 908 ABP) were observed. Separate samples were coked to 1.4, 2.5 and 3.4 mass %, and other samples were treated by soaking in 25 mass % ammonia solution, drying and calcining (523 K: 1 h: 923 K: 5.5 h). Results reported are the average of 10 experiments (standard deviation of less than 2%). Initial experiments were carried out to compare the reactions of squalane over equilibrium catalyst with and without pre-treatment. All pre-treatments were found to decrease conversion, with pre-coking having a significant effect on LCO yield and on further coke formation. The results were consistent with pore blocking effects, and comparisons were made with an ammonia pre-treated catalyst where the pore structure remained the same. Compared to the equilibrated catalyst, it was surprising to find higher yields of lower molecular weight compounds at the expense of C{sub 7}{sup +} products, both at 38 and 65 mass % conversion. Hydrogen transfer reactions are known to

  13. Characterization of the efficiency of the gas-solid contact in circulating bed at by the use of a test reaction: the cumene catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, J.; Gauthier, T.; Pontier, R. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France); Briens, C.L.; Bergougnou, M. [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1995-12-31

    The gas-solid down with the stream reactor, the ``downer``, presents a main interest for the high-speed reactions because it is well adapted to hard conditions uses: very short residence times, high temperatures and feeds of catalyst. This reactor type already presents a certain advantage to estimate the charges or new catalysts potential. But, it particularly constitutes an interesting option for some processes as petroleum cuts catalytic cracking. In order to intensify the contact between the catalyst and the reagents, the temperature increase of the reagents has to be almost instantaneous and the initial contact between the gas and the solid particles particularly effective. So as to validate these two hypothesis, the test reaction of the cumene catalytic cracking is carried out in the pilot unit ``downer`` of the Western Ontario University. (O.M.). 11 refs., 3 figs.

  14. Fuel and engine characterization study of catalytically cracked waste transformer oil

    KAUST Repository

    Prasanna Raj Yadav, S.

    2015-05-01

    This research work targets on the effective utilization of WTO (waste transformer oil) in a diesel engine and thereby, reducing the environmental problems caused by its disposal into open land. The novelty of the work lies in adoption of catalytic cracking process to chemically treat WTO, wherein waste fly ash has been considered as a catalyst for the first time. Interestingly, both the oil and catalyst used are waste products, enabling reduction in total fuel cost and providing additional benefit of effective waste management. With the considerable token that use of activated fly ash as catalyst requires lower reaction temperature, catalytic cracking was performed only in the range of 350-400°C. As a result of this fuel treatment process, the thermal and physical properties of CCWTO (catalytically cracked waste transformer oil), as determined by ASTM standard methods, were found to be agreeable for its use in a diesel engine. Further, FTIR analysis of CCWTO discerned the presence of essential hydrocarbons such as carbon and hydrogen. From the experimental investigation of CCWTO - diesel blends in a diesel engine, performance and combustion characteristics were shown to be improved, with a notable increase in BTE (brake thermal efficiency) and PHRR (peak heat release rate) for CCWTO 50 by 7.4% and 13.2%, respectively, than that of diesel at full load condition. In the same note, emissions such as smoke, HC (hydrocarbon) and CO (carbon monoxide) were noted to be reduced at the expense of increased NOx (nitrogen oxides) emission. © 2015 Elsevier Ltd. All rights reserved.

  15. An Experimental Study on Catalytic Cracking of Polyethylene and Engine Oils

    Directory of Open Access Journals (Sweden)

    S.K. Kimutai

    2014-02-01

    Full Text Available The utility of plastics and engine oils is very important due to their wide application in the packaging and automotive industries respectively and as such their continued use has led to an in increase in plastics and oil waste. However, the huge amount of plastic and engine oil waste produced may be treated with thermal catalytic methods to produce fossil fuel substitutes. In this research, the co-processing of polyethylene resin with petrol engine oil into high value hydrocarbons using thermal catalytic cracking (consisting of initial pyrolytic stage followed by a catalytic reforming stage was investigated. Plastic resins and petrol engine oil were loaded in the thermal reactor and HZSM-5 zeolite catalyst placed in the catalytic chamber. The system was purged with nitrogen at temperatures between 400 and 520oC. The resulting products were compared with those obtained in the absence of a catalyst. At temperatures greater than 460oC the conversion into liquid and gas fuels is above 70% wt. At similar temperatures and in the absence of catalyst, thermal cracking of low density polyethylene generated majorly liquid products with a low calorific value. The use of HZSM-5 as a catalyst caused a significant increase in the proportion of gaseous hydrocarbons that consisted mainly of light fraction olefins and liquid oil with calorific value of 43.9 MJ/kg and also comparable to regular petrol fuel. This study focuses on developing a method of conversion that can be adopted by industries as a means of converting waste plastics and waste oils into resources rather than waste.

  16. Effects of Light Rare Earth on Acidity and Catalytic Performance of HZSM-5 Zeolite for Catalytic Cracking of Butane to Light Olefins

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaoning; Zhao Zhen; Xu Chunming; Duan Aijun; Zhang Li; Jiang Guiyuan

    2007-01-01

    The effects of rare earth (RE) on the structure, acidity, and catalytic performance of HZSM-5 zeolite were investigated. A series of RE/HZSM-5 catalysts, containing 7.54% RE (RE=La, Ce, Pr, Nd, Sm, Eu or Gd), were prepared by the impregnation of the ZSM-5 type zeolites (Si/Al=64:1) with the corresponding RE nitrate aqueous solutions. The catalysts were characterized by means of FT-IR, UV-Vis, NH3-TPD, and IR spectroscopy of adsorbed pyridine. The catalytic performances of the RE/HZSM-5 for the catalytic cracking of mixed butane to light olefins were also measured with a fixed bed microreactor. The results revealed that the addition of light rare earth metal on the HZSM-5 catalyst greatly enhanced the selectivity to olefins, especially to propylene, thus increasing the total yield of olefins in the catalytic cracking of butane. Among the RE-modified HZSM-5 samples, Ce/HZSM-5 gave the highest yield of total olefins, and Nd/HZSM-5 gave the highest yield of propene at a reaction temperature of 600℃. The presence of rare earth metal on the HZSM-5 sample, not only modified the acidic properties of HZSM-5 including the amount of acid sites and acid type, that is, the ratio of L/B (Lewis acid/Bronsted acid), but also altered the basic properties of it, which in turn promoted the catalytic performance of HZSM-5 for the catalytic cracking of butane.

  17. Microstructural analysis and the mechanism if the coke formation in a refractory castable used in a fluidized catalytic cracking unit; Analise microestructural e mecanismo de formacao do coque em um concreto refratario utilizado em unidades de craqueamento catalitico fludizado

    Energy Technology Data Exchange (ETDEWEB)

    Cabrelon, M.D.; Rodrigues, J.A. [Universidade Federal de Sao Carlos (GEMM/UFSCAR), Sao Carlos, SP (Brazil). Grupo de Engenharia de Microestrutura de Materiais], Email: marcelodezena@gmail.com; Medeiros, J. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Toledo Filho, R.D. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Estruturas e Materiais

    2010-07-01

    The cokes formation in the refractory castables for FCC's unit is cited as one the most relevant problem in the internal face of the petrochemical Riser, but its mechanism is still unknown. In this sense, was made a microstructural study with a anti-erosive refractory castable class C, exposed to a cokemaker atmosphere, aiming to identify a mechanism to explain the coke's formation. For this reason, test samples were molded and subjected to a cokemaker process in the reactor pilot from CENPES-PETROBRAS-RJ, under an atmosphere of propene, as one temperature of 540 deg C and soaking time ranging between 10 and 480h. These samples had their internal and surface microstructures analyzed by Optical and Scanning Electron Microscopy. The results showed that the aggregates had deterioration and your internal pores were filled with coke. In this point, starts the growth of microspheres of coke on the external face, coalescing and forming 'columns' in which become denser when increasing the exposure time to a saturated atmosphere with hydrocarbon. (author)

  18. Production of Low-carbon Light Olefins from Catalytic Cracking of Crude Bio-oil

    Institute of Scientific and Technical Information of China (English)

    Yan-ni Yuan; Tie-jun Wang; Quan-xin Li

    2013-01-01

    Low-carbon light olefins are the basic feedstocks for the petrochemical industry.Catalytic cracking of crude bio-oil and its model compounds (including methanol,ethanol,acetic acid,acetone,and phenol) to light olefins were performed by using the La/HZSM-5 catalyst.The highest olefins yield from crude bio-oil reached 0.19 kg/(kg crude bio-oil).The reaction conditions including temperature,weight hourly space velocity,and addition of La into the HZSM-5 zeolite can be used to control both olefins yield and selectivity.Moderate adjusting the acidity with a suitable ratio between the strong acid and weak acid sites through adding La to the zeolite effectively enhanced the olefins selectivity and improved the catalyst stability.The production of light olefins from crude bio-oil is closely associated with the chemical composition and hydrogen to carbon effective ratios of feedstock.The comparison between the catalytic cracking and pyrolysis of bio-oil was studied.The mechanism of the bio-oil conversion to light olefins was also discussed.

  19. Catalytic cracking of 1-butene to propylene by Ag modified HZSM-5

    Institute of Scientific and Technical Information of China (English)

    Rongrong Zhang; Zhengbao Wang

    2015-01-01

    Silver modified HZSM-5 (AgHZ) zeolite catalysts were prepared by ion exchange method and their catalytic properties in the 1-butene cracking reaction were measured. The catalysts were characterized by infrared spec-troscopy with pyridine adsorption (Py-IR), N2 adsorption and X-ray diffraction (XRD). The effects of Ag loading and steaming treatment on catalytic performances were studied. It is found that the activity of HZSM-5 (HZ) cat-alyst significantly decreases with the steaming time, whereas AgHZ catalysts show stable activity in the steaming time of 24–48 h and their activities increase with the Ag loading. When the steaming time is 24–48 h, the yield of propylene over HZ catalyst significantly decreases, whereas it is stable over AgHZ catalysts. The AgHZ catalysts with Ag loadings of 0.28%–0.43%(by mass) show similar propylene yields (~30%), which are higher than that over the AgHZ catalyst with a Ag loading of 0.55%(by mass). These results indicate that the steam-treated AgHZ catalysts with optimum Ag loadings have higher yield of propylene and are more stable than the steam-treated HZ catalyst. The regeneration stability measurement in butene cracking also shows that the AgHZ catalyst steam-treated under a suitable condition has better stability than the HZ catalyst.

  20. Simultaneous realization of high catalytic activity and stability for catalytic cracking of n-heptane on highly exposed (010) crystal planes of nanosheet ZSM-5 zeolite.

    Science.gov (United States)

    Xiao, Xia; Zhang, Yaoyuan; Jiang, Guiyuan; Liu, Jia; Han, Shanlei; Zhao, Zhen; Wang, Ruipu; Li, Cong; Xu, Chunming; Duan, Aijun; Wang, Yajun; Liu, Jian; Wei, Yuechang

    2016-08-01

    Nanosheet ZSM-5 zeolite with highly exposed (010) crystal planes demonstrates high reactivity and good anti-coking stability for the catalytic cracking of n-heptane, which is attributed to the synergy of high external surface area and acid sites, fully accessible channel intersection acid sites, and hierarchical porosity caused by the unique morphology.

  1. Bring into Full Play the Role of Catalytic Reforming Unit

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This article after analyzing the current status of catalytic reforming technology in China puts forward a host of problems related with catalytic reforming capacity, feedstock, size and techno-economic indicators. To solve these problems it is proposed to properly increase the catalytic reforming capacity,extend the feedstock source, and eliminate the bottlenecks to boost the capacity of existing units, improve the operating and management level, as well as speed up R&D work, disseminate new technologies, new processes and novel catalysts.

  2. Study on the Performance and Commercial Application of New Generation DMMC-1 Type Catalyst for Deep Catalytic Cracking

    Institute of Scientific and Technical Information of China (English)

    Long Jun; Tian Huiping; Liu Yujian; Xie Chaogang; Li Jibing

    2007-01-01

    Over the past decades SINOPEC has been uninterruptedly engaging in the development and upgrading of deep catalytic cracking(DCC)technology for manufacturing propylene from heavy oil.Recently SINOPEC after having made a lot of progress in the area of oil refining at the molecular level has developed a new generation DMMC-1 type catalyst designed for the DCC process.The laboratory evaluation tests have shown that compared to the existing MMC-2 type catalyst that features the best comprehensive performance,the DMMC-1 type catalyst has increased the propylene yield by 2.2% with the propylene selectivity increased by 10%.The saidcatalyst has improved its ability for heavy oil cracking and coke selectivity along with reduction of olefin content in gasoline to achieve a better product distribution and improve the product quality.The resuIts of application of the said catalyst in a 650-kt/a commercial DCC unit at SINOPEC Anqing Branch Company have revealed that the DMMC-1 catalyst demonstrated an enhanced capabilitv for heavy oil cracking and could increase the total liquid yield to 84.56 m%from 83.92 m%,the LPG vield to 38.90 m% from 34.60 m%,the propylene yield to 17.80 m% from 15.37 m% and the propylene concentration to 45.91 m% from 44.91 m%,and reduce the coke yield from 7.61 m% to 7.05 m% and the olefin content in gasoline from 42.3v% to 37.5 v%,resulting in an incremental profit amounting to 52.19 million RMB a year.This technology has further upgradedand developed the DCC technology which has been commanding a leading position among the industry peers.

  3. Computer simulation of the performance of fluid catalytic cracking risers and downers

    Energy Technology Data Exchange (ETDEWEB)

    Bolkan-Kenny, Y.G.; Pugsley, T.S.; Berruti, F. (Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering)

    1994-12-01

    Newly developed zeolite catalysts for the fluid catalytic cracking (FCC) process are typically characterized by high activity and rapid deactivation. Modifications of conventional FCC reactors are necessary to avoid severe backmixing which decreases selectivities and yields and to take full advantage of new catalysts. Recent studies suggest that more uniform flow, better reaction control, shorter residence times with narrower residence time distributions (RTD), and higher catalyst/oil ratios can be achieved in downflow systems (downers) compared to upflow systems (risers). In this work, a novel computer simulation of a FCC downer reactor is introduced. Comparison of downer and riser models for the FCC process shows that downers are slightly more beneficial than risers when commercial silica-alumina catalysts are used. In the case of the FCC process using zeolite catalysts, the benefits of downers become more significant.

  4. Study on Mechanism for Formation of Carbon Oxides During Catalytic Cracking of High Acidic Crude

    Institute of Scientific and Technical Information of China (English)

    Wei Xiaoli; Mao Anguo; Xie Chaogang

    2007-01-01

    Based on the basis of analysis and interpretation of the products distribution of catalytic cracking of high acidic crude,the mechanism for decarboxylation of petroleum acids during FCC process was discussed.The protons originated from the Br(o)nsted acid sites can combine with oxygen of the carbonyl groups with more negative charges to form reaction intermediates that Call be subjected to cleavage at the weak bonds,leading to breaking of carboxylic groups from the carboxylic acids followed by its decomposition to form alkyl three-coordinated carbenium ions,CO and H2O.The Lewis acid as an electrophilic reagent can abstract carboxylic groups from carboxylic acids to subsequently release CO2.

  5. Study on reformulation of fluid catalytic cracking gasoline and increasing production of light olefins

    Institute of Scientific and Technical Information of China (English)

    Pingxiang YAN; Xianghai MENG; Jinsen GAO; Chunmin XU; Zhiyu SUI

    2008-01-01

    The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction con-ditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production.

  6. Novel equipment for testing catalytic cracking and catalyst regeneration with short contact times

    Energy Technology Data Exchange (ETDEWEB)

    Lipiaeinen, K.; Hagelberg, P.; Aittamaa, J.; Eilos, I.; Hiltunen, J.; Niemi, V.M. [Fortum Oil and Gas Oy, P. O. Box 310, FIN-06101 Porvoo (Finland); Krause, A.O.I. [Helsinki University of Technology, Department of Chemical Technology, P. O. Box 6100, FIN-02015 HUT (Finland)

    1999-07-19

    A new piece of equipment was developed for testing catalytic cracking and catalyst regeneration, particularly for short contact times. The gas oil to be cracked is injected into the upper section of the reactor, which can be operated in the temperature range 400-800C, catalyst-to-oil ratios from 0 to 300g{sub cat}/g{sub oil} and residence times between 0.01 and 2.3s. The product is led directly into the analysis section where hydrocarbons from C{sub 1} to C{sub 12} (in total 350 compounds) are separated by a capillary column. In catalyst regeneration studies oxygen/nitrogen pulses are fed into the reactor via a gas-loop. The carbon monoxide and carbon dioxide formed are first separated in a packed column after which they are converted to methane by hydrogen on a Ni/{gamma}-Al{sub 2}O{sub 3} catalyst ensuring the determination of even small amounts of coke. The reproducibility of the experiments has proved to be excellent. With this new reactor system, accurate information can be obtained on the initial activity of the catalyst and product distribution

  7. Effects of Calcination Temperature on the Acidity and Catalytic Performances of HZSM-5 Zeolite Catalysts for the Catalytic Cracking of n-Butane

    Institute of Scientific and Technical Information of China (English)

    Jiangyin Lu; Zhen Zhao; Chunming Xu; Aijun Duan; Pu Zhang

    2005-01-01

    The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature.The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.

  8. Analysis of cracked core spray piping from the Quad Cities Unit 2 boiling water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Diercks, D.R.; Gaitonde, S.M.

    1982-09-01

    The results of a metallurgical analysis of leaking cracks detected in the core spray injection piping of Commonwealth Edison Company's Quad Cities Unit 2 Boiling Water Reactor are described. The cracks were present in a welded 105/sup 0/ elbow assembly in the line, and were found to be caused by intergranular stress corrosion cracking associated with the probable presence of dissolved oxygen in the reactor cooling water and the presence of grain boundary sensitization and local residual stresses induced by welding. The failure is unusual in several respects, including the very large number of cracks (approximately 40) present in the failed component, the axial orientation of the cracks, and the fact that at least one crack completely penetrated a circumferential weld. Virtually all of the cracking occurred in forged material, and the microstructural evidence presented suggests that the orientation of the cracks was influenced by the presence of axially banded delta ferrite in the microstructure of the forged components.

  9. Thermal and catalytic cracking of ethylene in presence of CaO, MgO, zeolite and calcined dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Taralas, G.; Sjoestroem, K.; Jaeraas, S.; Bjoernbom, E. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1993-12-31

    The subject of the present work is to study the effect of catalysts such as calcined dolomite (CaO.MgO), CaO (quicklime), MgO and Zeolite (EKZ-4) on the cracking of ethylene in the presence and absence of steam. N-heptane, toluene, naphthalene, thiophene have been some suitable model compounds for studies of the thermal and catalytic decomposition of tar. Previous results showed that the reaction scheme of the thermal decomposition of n-heptane was consistent with the high yield of ethylene observed in thermal decomposition of n-heptane. The effect of the reactor wall and the ferric impurities in the dolomite are also subjects of the research in this study. The results may also throw some additional light on the nature of the gas-phase thermal and catalytic reactions occurring in the use of dolomite as tar cracking catalysts. 28 refs

  10. Kinetic and Phase Behaviors of Catalytic Cracking Dry Gas Hydrate in Water-in-Oil Emulsion

    Institute of Scientific and Technical Information of China (English)

    MA Qinglan; HUANG Qiang; CHEN Guangjin; WANG Xiulin; SUN Changyu; YANG Lanying

    2013-01-01

    The systematic experimental studies were performed on the hydrate formation kinetics and gas-hydrate equilibrium for a simulated catalytic cracking gas in the water-in-oil emulsion.The effect of temperature,pressure and initial gas-liquid ratio on the hydrate formation was studied,respectively.The data were obtained at pressures ranging from 3.5 to 5 MPa and temperatures from 274.15 to 277.15 K.The results showed that hydrogen and methane can be separated from the C2+ fraction by forming hydrate at around 273.15 K which is much higher temperature than that of the cryogenic separation method,and the hydrate formation rate can be enhanced in the water-in-oil emulsion compared to pure water.The experiments provided the basic data for designing the industrial process,and setting the suitable operational conditions.The measured data of gas-hydrate equilibria were compared with the predictions by using the Chen-Guo hydrate thermodynamic model.

  11. Study of Carbon Nanotube Supported Co-Mo Selective Hydrodesulphurization Catalysts for Fluid Catalytic Cracking Gasoline

    Institute of Scientific and Technical Information of China (English)

    Wenkui Yin; Mei Li; Hongyan Shang; Chenguang Liu; Fei Wei

    2005-01-01

    In this paper,carbon nanotube supported Co-Mo catalysts for selective hydrodesulphurization (HDS) of fluid catalytic cracking (FCC) gasoline were studied,using di-isobutylene,cyclohexene,1-octene and thiophene as model compounds to simulate FCC gasoline. The results show that the Co-Mo/CNT has very high HDS activity and HDS/hydrogenation selectivity comparing with the Co-Mo/γ-Al2O3 and Co-Mo/AC catalyst systems. The saturation ratio of cyclohexene was lower than 50%,and the saturation ratio of 1,3-di-isobutylene lower than 60% for the Co-Mo/CNT catalysts. Co/Mo atomic ratio was found to be one of the most important key factors in influencing the hydrogenation selectivity and HDS activity,and the most suitable Co/Mo atomic ratio was 0.4. Co/CNT and Mo/CNT mono-metallic catalysts showed lower HDS activity and selectivity than the Co-Mo/CNT bi-metallic catalysts.

  12. Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

    Directory of Open Access Journals (Sweden)

    Toshiyuki Kimura

    2012-01-01

    Full Text Available In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT, hydrocracking (HC, and catalytic cracking (CC of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al2O3/H-USY and ns Al2O3/H-GaAlMFI; HC: [Ni-Mo/γ-Al2O3]/ns Al2O3/H-beta were studied. The major product from CC on ns Al2O3/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products.

  13. ACIDIC REMOVAL OF METALS FROM FLUIDIZED CATALYTIC CRACKING CATALYST WASTE ASSISTED BY ELECTROKINETIC TREATMENT

    Directory of Open Access Journals (Sweden)

    R. B. G. Valt

    2015-06-01

    Full Text Available AbstractOne of the main uses of catalysts in the oil industry is in the fluidized catalytic cracking process, which generates large quantities of waste material after use and regeneration cycles and that can be treated by the electrokinetic remediation technique, in which the contaminant metals are transported by migration. In this study, deactivated FCC catalyst was characterized before and after the electrokinetic remediation process to evaluate the amount of metal removed, and assess structural modifications, in order to indicate a possible use as an adsorbent material. The analyses included pH measurement and the concentration profile of vanadium ions along the reactor, X-ray microtomography, X-ray fluorescence, BET analysis and DTA analysis. The results indicated that 40% of the surface area of the material was recovered in relation to the disabled material, showing an increase in the available area for the adsorption. The remediation process removed nearly 31% of the vanadium and 72% of the P2O5 adhering to the surface of the catalyst, without causing structural or thermal stability changes.

  14. Conversion of isoprenoid oil by catalytic cracking and hydrocracking over nanoporous hybrid catalysts.

    Science.gov (United States)

    Kimura, Toshiyuki; Liu, Chen; Li, Xiaohong; Maekawa, Takaaki; Asaoka, Sachio

    2012-01-01

    In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al₂O₃ and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al₂O₃/H-USY and ns Al₂O₃/H-GaAlMFI; HC: [Ni-Mo/γ-Al₂O₃]/ns Al₂O₃/H-beta) were studied. The major product from CC on ns Al₂O₃/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products. PMID:22791962

  15. Optimizing the Production of Renewable Aromatics via Crop Oil Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Clancy Kadrmas

    2015-04-01

    Full Text Available While HZSM-5 catalytic cracking of crop oil toward aromatics have been well documented, this work adds to this body of knowledge with a full acid byproduct analysis that provides improved mass balance closure along with a design of experiment optimization of reaction conditions. Fatty acids are an inevitable byproduct when converting any triglyceride oil, but are most often overlooked; despite the impact fatty acids have on downstream processing. Acid analysis verified that only short chain fatty acids, mainly acetic acid, were present in low quantities when all feed oil was reacted. When relatively high fatty acid amounts were present, these were mainly uncracked C16 and C18 fatty acids. Optimization is a balance of aromatics formation vs. unwanted gas products, coke and residual fatty acids. A design of experiments approach was used to provide insight into where the optimal reaction conditions reside for HZSM-5 facilitated reactions. These conditions can then form the basis for further development into a commercially viable process for the production of renewable aromatics and other byproducts.

  16. Catalytic Cracking and PSO-RBF Neural Network Model of FCC Cycle Oil

    Institute of Scientific and Technical Information of China (English)

    Liu Yibin; Tu Yongshan; Li Chunyi; Yang Chaohe

    2013-01-01

    Catalytic cracking experiments of FCC cycle oil were carried out in a ifxed lfuidized bed reactor. Effects of reac-tion conditions, such as temperature, catalyst to oil ratio and weight hourly space velocity, were investigated. Hydrocarbon composition of gasoline was analyzed by gas chromatograph. Experimental results showed that conversion of cycle oil was low on account of its poor crackability performance, and the effect of reaction conditions on gasoline yield was obvi-ous. The parafifn content was very high in gasoline. Based on the experimental yields under different reaction conditions, a model for prediction of gasoline and diesel yields was established by radial basis function neural network (RBFNN). In the model, the product yield was viewed as function of reaction conditions. Particle swarm optimization (PSO) algorithm with global search capability was used to obtain optimal conditions for a highest yield of light oil. The results showed that the yield of gasoline and diesel predicted by RBF neural network agreed well with the experimental values. The optimized reac-tion conditions were obtained at a reaction temperature of around 520℃, a catalyst to oil ratio of 7.4 and a space velocity of 8 h-1. The predicted total yield of gasoline and diesel reached 42.2% under optimized conditions.

  17. Visualizing Dealumination of a Single Zeolite Domain in a Real-Life Catalytic Cracking Particle.

    Science.gov (United States)

    Kalirai, Sam; Paalanen, Pasi P; Wang, Jian; Meirer, Florian; Weckhuysen, Bert M

    2016-09-01

    Fluid catalytic cracking (FCC) catalysts play a central role in the chemical conversion of crude oil fractions. Using scanning transmission X-ray microscopy (STXM) we investigate the chemistry of one fresh and two industrially deactivated (ECAT) FCC catalysts at the single zeolite domain level. Spectro-microscopic data at the Fe L3 , La M5 , and Al K X-ray absorption edges reveal differing levels of deposited Fe on the ECAT catalysts corresponding with an overall loss in tetrahedral Al within the zeolite domains. Using La as a localization marker, we have developed a novel methodology to map the changing Al distribution of single zeolite domains within real-life FCC catalysts. It was found that significant changes in the zeolite domain size distributions as well as the loss of Al from the zeolite framework occur. Furthermore, inter- and intraparticle heterogeneities in the dealumination process were observed, revealing the complex interplay between metal-mediated pore accessibility loss and zeolite dealumination.

  18. Multiple steady states of fluid catalytic cracking unit with high-efficiency regenerator:effect of reaction temperature control strategy on heat feedback%高效再生催化裂化装置多稳态分析:反应温度开/闭环控制条件对热反馈机制的影响

    Institute of Scientific and Technical Information of China (English)

    王锐; 罗雄麟; 许锋

    2014-01-01

    针对催化裂化反应-再生系统在提升管反应温度开环和闭环控制条件下的输出与输入多稳态问题,分析了烧焦罐式高效再生催化裂化反应-再生系统在两种条件下随着CO助燃剂添加量变化时的多稳态分布。在反应温度开环条件下,因再生温度与反应温度的耦合程度较低,使系统移热曲线呈单调递增,导致了系统出现3个稳态操作点。在反应温度闭环控制条件下,提升管反应器和再生器间热反馈机制发生改变,由于再生剂循环量可以作为额外的自由度对再生温度和反应温度之差进行补偿,再生器和提升管反应器的耦合程度增强,使得系统只会在助燃剂添加量极低时才会出现多个稳态点,而在基准操作条件下只有一个稳态点,规避了系统在提升管反应温度开环时的多个稳态点的问题。%Analyses of multiple steady states of a fluid catalytic cracking unit (FCCU) with high-efficiency regenerator with the riser reaction temperature under open loop and closed loop control were performed based on the theory of output multiplicity and input multiplicity. The multiple steady states under these two conditions were determined with respect to the amount of the added CO combustion promoter. The heat removal curve was found monotonously increasing with riser reaction temperature under open loop control, which resulted in the existence of three multiple steady states because of weak coupling between regenerator temperature and riser reaction temperature. On the other hand, the heat feedback of regenerator and riser reactor changed under closed loop control because regenerated catalyst flow rate could be used as an extra measure to compensate the difference between regenerator temperature and riser reaction temperature to enhance coupling between regerator temperature and riser reactor temperature. Multiple steady states would exist only when CO promoter was extremely

  19. NSTS Orbiter auxiliary power unit turbine wheel cracking risk assessment

    Science.gov (United States)

    Cruse, T. A.; Mcclung, R. C.; Torng, T. Y.

    1992-01-01

    The present investigation of turbine-wheel cracking problems in the hydrazine-fueled APU turbine wheel of the Space Shuttle Orbiter's Main Engines has indicated the efficacy of systematic probabilistic risk assessment in flight certification and safety resolution. Nevertheless, real crack-initiation and propagation problems do not lend themselves to purely analytical studies. The high-cycle fatigue problem is noted to generally be unsuited to probabilistic modeling, due to its extremely high degree of intrinsic scatter. In the case treated, the cracks appear to trend toward crack arrest in a low cycle fatigue mode, due to a detuning of the resonance model.

  20. Prediction of gasoline yield in a fluid catalytic cracking (FCC riser using k-epsilon turbulence and 4-lump kinetic models: A computational fluid dynamics (CFD approach

    Directory of Open Access Journals (Sweden)

    Muhammad Ahsan

    2015-07-01

    Full Text Available Fluid catalytic cracking (FCC is an essential process for the conversion of gas oil to gasoline. This study is an effort to model the phenomenon numerically using commercial computational fluid dynamics (CFD software, heavy density catalyst and 4-lump kinetic model. Geometry, boundary conditions and dimensions of industrial riser for catalytic cracking unit are conferred for 2D simulation using commercial CFD code FLUENT 6.3. Continuity, momentum, energy and species transport equations, applicable to two phase solid and gas flow, are used to simulate the physical phenomenon as efficient as possible. This study implements and predicts the use of the granular Eulerian multiphase model with species transport. Time accurate transient problem is solved with the prediction of mass fraction profiles of gas oil, gasoline, light gas and coke. The output curves demonstrate the breaking of heavy hydrocarbon in the presence of catalyst. An approach proposed in this study shows good agreement with the experimental and numerical data available in the literature.

  1. Studies on the behaviour of different spent fluidized-bed catalytic cracking catalysts on Portland cement

    Directory of Open Access Journals (Sweden)

    Soriano, L.

    2009-12-01

    Full Text Available The fluidized-bed catalytic cracking catalyst (FCC it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to their characteristics. Thus, a study on five different FCC residues, supplied from different companies, has been carried out, and their physical-chemical characteristics, pozzolanic reactivity by means of thermogravimetric analysis and the evolution of the mechanical strength of mortars were studied. After analyzing all the aspects, it can be concluded that no significant differences among the different tested catalysts were found.El catalizador de craqueo catalítico (FCC es un residuo de la industria del petróleo que posee una elevada reactividad puzolánica y en matrices cementicias mejora de manera importante los aspectos mecánicos así como de durabilidad. En este trabajo se realiza un estudio comparativo sobre residuos de catalizador de distintos orígenes, para poder conocer si se pueden utilizar conjuntamente de forma indiscriminada o por el contrario hay que catalogarlos según su origen. Para ello, se realizó un estudio sobre cinco residuos de catalizador de craqueo catalítico distintos, suministrados por diferentes empresas y se estudiaron sus características fisicoquímicas, reactividad puzolánica a través de estudios termogravimétricos y la evolución de las resistencias mecánicas en morteros. Tras analizar todos los aspectos se concluye que no existen diferencias significativas entre los distintos catalizadores empleados.

  2. Fluid catalytic cracking: recent developments on the grand old lady of zeolite catalysis.

    Science.gov (United States)

    Vogt, E T C; Weckhuysen, B M

    2015-10-21

    Fluid catalytic cracking (FCC) is one of the major conversion technologies in the oil refinery industry. FCC currently produces the majority of the world's gasoline, as well as an important fraction of propylene for the polymer industry. In this critical review, we give an overview of the latest trends in this field of research. These trends include ways to make it possible to process either very heavy or very light crude oil fractions as well as to co-process biomass-based oxygenates with regular crude oil fractions, and convert these more complex feedstocks in an increasing amount of propylene and diesel-range fuels. After providing some general background of the FCC process, including a short history as well as details on the process, reactor design, chemical reactions involved and catalyst material, we will discuss several trends in FCC catalysis research by focusing on ways to improve the zeolite structure stability, propylene selectivity and the overall catalyst accessibility by (a) the addition of rare earth elements and phosphorus, (b) constructing hierarchical pores systems and (c) the introduction of new zeolite structures. In addition, we present an overview of the state-of-the-art micro-spectroscopy methods for characterizing FCC catalysts at the single particle level. These new characterization tools are able to explain the influence of the harsh FCC processing conditions (e.g. steam) and the presence of various metal poisons (e.g. V, Fe and Ni) in the crude oil feedstocks on the 3-D structure and accessibility of FCC catalyst materials. PMID:26382875

  3. Effect of Water Vapour on the Acidity of ZSM-5Zeolite Used for Catalytic Cracking of Naphtha to Manufacture Ethylene and Propylene

    Institute of Scientific and Technical Information of China (English)

    Ma Guangwei; Xiao Jingxian; ZhangHuining; Xie Zaiku

    2008-01-01

    The change in acidity of the ZSM-5 zeolite was investigated after it was treated with water vapour,and its capability on ammonia adsorption was also studied after having adsorbed water vapour.The effect of water vapour on products distribution was studied during catalytic cracking of naphtha,the changes in the adsorption ability and catalytic performance of the ZSM-5 zeolite was investigated after the catalyst was loaded with phosphorus species.These results all indicated that water vapour could reduce the acid strength and acid density of ZSM-5 zeolite and affect the capability of ZSM-5 on adsorption of gases,therefore the activated energy contributed by the ZSM-5 zeolite to the catalytic cracking reaction would be low to prevent the feedstock from deepened catalytic cracking and coke formation.

  4. An alternative methodology for corrosion monitoring in cracking units; Metodologia alternativa para monitoramento da corrosao em unidades de craqueamento

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Patricia R.; Ponte, Haroldo de A. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Programa de Recursos Humanos para o Setor Petroleo e Gas (PRH-24/UFPR)

    2004-07-01

    Nowadays Brazilian oil refineries face an important challenge: to adjust their units to the processing of more aggressive crudes, containing high levels of nitrogen, like those deriving from national production. The use of this kind of oil has caused an increase on corrosion and hydrogen damages related to the simultaneous presence of sulfides and cyanides on process streams, mainly in Fluid Catalytic Cracking Units (FCCU's). Therefore, a new corrosion monitoring methodology has been proposed: the on-line evaluation of the iron sulfide film integrity by an electrochemical technique called voltammetry. Such approach could allow detecting and inhibiting the corrosive process at real time, before significant occurrence of hydrogen permeation, thus improving the reliability of industrial equipment. Laboratorial tests and preliminary assays in pilot scale indicated the application feasibility of the technique. The present work describes the proposed methodology, including some characteristics and its current development status. (author)

  5. Influence of Catalyst Type and Regeneration on Upgrading of Crude Bio-oil through Catalytical Thermal Cracking

    Institute of Scientific and Technical Information of China (English)

    郭晓亚; 颜涌捷; 李庭琛

    2004-01-01

    Catalysts, such as HZSM-5(Si/Al=50), HZSM-5(25), zeolite 5A, CaHZSM-5(50), ZnHZSM-5(50), and Kaolin were used in upgrading of crude biomass oil from pyrolysis in a fixed-bed reactor under atmospheric pressure, in order to investigate the effects of catalyst type on the yield of desired product. A blank test was carried out in a bed of inert packings to determine the extent of non-catalytical thermal cracking. The gas produced in the reaction was analyzed by the chemical absorption method. Among those catalysts, HZSM-5(50) gave the highest yield of the desired organic distillate while Kaolin gave the least formation of coke. Regeneration of deactivated HZSM-5(50) was studied. In terms of yield of organic distillate and formation rate of coke, the catalytic activity did not change much during the first 3 times of regeneration.

  6. Synergistic effect of W and P on ZSM-5 and its catalytic performance in the cracking of heavy oil

    Institute of Scientific and Technical Information of China (English)

    Dongmin Han; Nannan Sun; Jianwei Liu; Chunyi Li; Honghong Shan; Chaohe Yang

    2014-01-01

    In order to develop the conversion of heavy oil with a high yield of propylene in the catalytic cracking process, ZSM-5 zeolite was modified by tungsten and phosphorus, which was proved to be an effective method. Characterization results show that the improvement of catalytic performance could be correlated to the interaction of phosphorus and tungsten species on ZSM-5. P inhibited the aggregation of tungsten species on ZSM-5 and was conductive to convert the tungsten species with octahedral coordination into tetrahedral coordination. And this ultimately led to that more acid sites were reserved after hydrothermal treatment in the tungsten and phosphorus co-modified ZSM-5 catalyst. Phosphorus species played an important role to restrain the dehydrogenation activity of tungsten. In addition, a model reflecting the interaction between tungsten species and ZSM-5 framework was proposed.

  7. Progress of heavy oil catalytic cracking%重油催化裂解技术研究进展

    Institute of Scientific and Technical Information of China (English)

    盖希坤; 田原宇; 夏道宏; 邢仕杰

    2011-01-01

    Heavy oil catalytic cracking is an effective technology to convert heavy oil to lighter and more valuable product, including ethylene and propylene. The catalyst and reactor play an important role in the technology. In this paper, various catalysts and reactors for heavy oil catalytic cracking are summarized, and the application conditions of the catalysts and the hydrodynamic characteristics of the reactors are elaborated. Development of downer reactor and the corresponding catalyst are suggested to be the most promising research direction.%重油催化裂解技术以增产乙烯、丙烯等低碳烯烃为主要目标,是重油轻质化的有效手段.对催化裂解技术的研究,催化剂和反应器是其核心.本文综述了重油催化裂解技术中采用的各种催化剂和反应器的研究进展,阐述了不同催化剂的适用条件和不同类型反应器的流体特性,并指出深入研究下行床反应器及开发与之匹配的催化剂将是今后开发重油催化裂解技术最具潜力的研究方向.

  8. Analysis of the organic liquid produced from catalytic cracking of crude palm oil in the presence of alumina supported catalysts

    Science.gov (United States)

    Ramli, Anita; Razak, Rozlina Abdul

    2012-09-01

    Catalytic cracking of crude palm oil (CPO) was studied in the presence of alumina, 1% Pt/Al2O3 and 1% Pd/Al2O3 as catalyst. The CPO to catalyst weight ratio used was 1:0.05. The experiment was carried out in a simple liquid-phase batch reactor at atmospheric pressure where the sample was heated to 300-350 δC. Products formed were organic liquid products (OLP) and gaseous product with the solid residue remains in the reactor. The total conversion of CPO was only between 25 - 31% where the residue is suggested to be mainly of polimerised CPO. The OLP was analysed using a gas chromatography with FID detector. Analyses show that the selectivity to liquid fuel is influence by the catalyst used whereby Al2O3 gives the highest selectivity to gasoline while 1% Pt/Al2O3 has the highest selectivity to diesel. However, 1% Pd/Al2O3 is not a suitable catalyst for catalytic cracking of CPO to liquid fuel where less than 17.5% of OLP produced could be classified as liquid fuel.

  9. 催化裂化提升管反应器中颗粒聚团裂化反应的数值模拟%Numerical Predication of Cracking Reaction of Particle Clusters in Fluid Catalytic Cracking Riser Reactors

    Institute of Scientific and Technical Information of China (English)

    王淑彦; 陆慧林; 高金森; 徐春明; 孙丹

    2008-01-01

    Behavior of catalytic cracking reactions of particle cluster in fluid catalytic cracking(FCC)riser reac-tors was numerically analyzed using a four-lump mathematical model.Effects of the cluster porosity.inlet gas ve-locity and temperature,and coke deposition on cracking reactions of the cluster were investigated. Distributions of temperature,gases,and gasoline from both catalyst particle cluster and an isolated catalyst particle are presented.The reaction rates from vacuum gas oil(VGO)to gasoline,gas and coke of individual particle in the cluster arehigher than those of the isolated particle,but it reverses for the reaction rates from gasoline to gas and coke.Less gasoline is produccd bv particle clustering.Simulated results show that the produced mass fluxes of gas and gasolineincrease with the operating temperature and molar concentration of VGO,and decrease due to the formation of coke.

  10. Catalytic thermal cracking of post-consumer waste plastics to fuels: Part 1 - Kinetics and optimization

    Science.gov (United States)

    Thermogravimetric analysis (TGA) was used to investigate thermal and catalytic pyrolysis of waste plastics such as prescription bottles (polypropylene/PP), high density polyethylene, landfill liners (polyethylene/PE), packing materials (polystyrene/PS), and foams (polyurethane/PU) into crude plastic...

  11. Heavy Naphtha Fractions 85-155 °С Recycling in the Catalytic Reforming Industrial Unit

    OpenAIRE

    Chernyakova, Ekaterina Sergeevna; Koksharov, Anton; Ivanchina, Emilia Dmitrievna; Yakupova, Inna

    2015-01-01

    Catalytic naphtha reforming is a vital process for refineries due to the production of high-octane components, which is intensely demanded in our modern life. In these paper, the mathematical modelling method application for catalytic reforming installation of Komsomolsk oil-refinery is proposed. The mathematical model-based system "Catalyst Control" was used for catalytic reforming installation monitoring. The quality of the product from the unit was studied, with hydrocracking gasoline used...

  12. An Experimental Study on Catalytic Cracking of Polyethylene and Engine Oils

    OpenAIRE

    S.K. Kimutai; A.M. Muumbo; I.K. Chebii; A.K. Kiprop

    2014-01-01

    The utility of plastics and engine oils is very important due to their wide application in the packaging and automotive industries respectively and as such their continued use has led to an in increase in plastics and oil waste. However, the huge amount of plastic and engine oil waste produced may be treated with thermal catalytic methods to produce fossil fuel substitutes. In this research, the co-processing of polyethylene resin with petrol engine oil into high value hydrocarbons using ther...

  13. Transportation fuel production by combination of LDPE thermal cracking and catalytic hydroreforming

    International Nuclear Information System (INIS)

    Highlights: • h-Beta samples were impregnated with Ni nitrate to achieve Ni contents of 1.5%, 4%, 7% and 10%. • Larger and more easily reducible metal particles were obtained on Ni 7%/h-Beta and Ni 10%/h-Beta. • Higher Ni contents increased the amount of gases at the expenses of diesel fractions. • Maximum selectivity to automotive fuels (∼81%) was obtained with Ni 7%/h-Beta. • Ni loading also enhanced olefins saturation up to Ni 7%/h-Beta. - Abstract: Fuel production from plastics is a promising way to reduce landfilling rates while obtaining valuable products. The usage of Ni-supported hierarchical Beta zeolite (h-Beta) for the hydroreforming of the oils coming from LDPE thermal cracking has proved to produce high selectivities to gasoline and diesel fuels (>80%). In the present work, the effect of the Ni loading on Ni/h-Beta is investigated in the hydroreforming of the oils form LDPE thermal cracking. h-Beta samples were impregnated with Ni nitrate, calcined and reduced in H2 up to 550 °C to achieve different Ni contents: 1.5%, 4%, 7% and 10%. Larger and more easily reducible metal particles were obtained on Ni 7%/h-Beta and Ni 10%/h-Beta. Hydroreforming tests were carried out in autoclave reactor at 310 °C, under 20 bar H2, for 45 min. Ni content progressively increased the amount of gases at the expenses of diesel fractions, while gasoline remained approximately constant about 52–54%. Maximum selectivity to automotive fuels (∼81%) was obtained with Ni 7%/h-Beta. Ni loading also enhanced olefins saturation up to Ni 7%/h-Beta. High cetane indices (71–86) and octane numbers (89–91) were obtained over all the catalysts. Regarding the different studied Ni contents, Ni 7%/h-Beta constitutes a rather promising catalyst for obtaining high quality fuels from LDPE thermal cracking oils

  14. Catalytic cracking of non-edible sunflower oil over ZSM-5 for hydrocarbon bio-jet fuel.

    Science.gov (United States)

    Zhao, Xianhui; Wei, Lin; Julson, James; Qiao, Qiquan; Dubey, Ashish; Anderson, Gary

    2015-03-25

    Non-edible sunflower oils that were extracted from sunflower residual wastes were catalytically cracked over a ZSM-5 catalyst in a fixed-bed reactor at three different reaction temperatures: 450°C, 500°C and 550°C. The catalyst was characterized using XRD, FT-IR, BET and SEM. Characterizations of the upgraded sunflower oils, hydrocarbon fuels, distillation residues and non-condensable gases were carried out. The effect of the reaction temperature on the yield and quality of liquid products was discussed. The results showed that the reaction temperature affected the hydrocarbon fuel yield but had a minor influence on its properties. The highest conversion efficiency from sunflower oils to hydrocarbon fuels was 30.1%, which was obtained at 550°C. The reaction temperature affected the component content of the non-condensable gases. The non-condensable gases generated at 550°C contained the highest content of light hydrocarbons (C1-C5), CO, CO2 and H2. Compared to raw sunflower oils, the properties of hydrocarbon fuels including the dynamic viscosity, pH, moisture content, density, oxygen content and heating value were improved.

  15. Performance under sulfate attack of concrete additioned with fluid catalytic cracking catalyst residue (FCC and metakaolin (MK

    Directory of Open Access Journals (Sweden)

    Nancy Torres Castellanos

    2013-04-01

    Full Text Available In this work the evaluation of the performance of concrete added with Fluid Catalytic Cracking Catalyst residue (FCC from a Colombian petroleum company, under sulfate attack, is presented. The results of this concrete are compared with the results of Metakaolin (MK added concrete. The analysis of the pozzolanic materials included the determination of the particle size, the pozzolanic activity and the chemical and mineralogical composition. Different percentages of FCC were used as Portland cement replacement in proportions of 0, 10, 20 and 30%; similarly concrete added with 20% of MK as replacement was elaborated. Compressive strength and performance under sulfate attack were evaluated. Results showed that concrete with FCC and MK as well as control concrete had similar behavior; however its expansion was higher. In addition, the performance of the two types of concrete (FCC y MK under sulfate attack was comparable; this could be due to fact that FCC and MK showed similarities regarding of their chemical and mineralogical composition. Importantly, after 360 days of exposure the specimens with MK and FCC showed no significant deterioration.

  16. 催化裂化柴油颜色安定性研究%The Studies on Color Stability of Catalytically Cracked Diesel Oil

    Institute of Scientific and Technical Information of China (English)

    王伟; 王超; 刘晓瑞; 崔艳红; 田红丽

    2012-01-01

    The color of diesel oil quickly turned depth during storage process,and generated a lot of sediment,which seriously affected its usage performance.With appropriate separation methods,the type and structure of color materials of catalytic cracking diesel oil were analyzed by combined liquid chromatography and mass spectrometry(LC/MS) and gas chromatography and mass spectrometry(GC/MS).Through the contrast of hydrofining diesel oil and catalytic cracking diesel oil of non-hydrocarbon material structure,the main material may cause the catalytic cracking diesel oil color was proposed.%柴油在储存过程中颜色快速变深,有大量沉渣生成,严重影响其使用性能。本课题选择合适的分离方法对催化裂化柴油中的显色物质用液相色谱与质谱(LC/MS)、气相色谱与质谱(GC/MS)联用技术分析、鉴定柴油主要显色物质的类别、结构,对比加氢精制柴油和催化裂化柴油存在的非烃类物质的结构,提出了可能引起催化裂化柴油变色的主要物质。

  17. Multiphase flow modelling using non orthogonal collocated finite volumes : application to fluid catalytical cracking and large scale geophysical flows.

    Science.gov (United States)

    Martin, R. M.; Nicolas, A. N.

    2003-04-01

    A modeling approach of gas solid flow, taking into account different physical phenomena such as gas turbulence and inter-particle interactions is presented. Moment transport equations are derived for the second order fluctuating velocity tensor which allow to involve practical closures based on single phase turbulence modeling on one hand and kinetic theory of granular media on the other hand. The model is applied to fluid catalytic cracking processes and explosive volcanism. In the industry as well as in the geophysical community, multiphase flows are modeled using a finite volume approach and a multicorrector algorithm in time in order to determine implicitly the pressures, velocities and volume fractions for each phase. Pressures, and velocities are generally determined at mid-half mesh step from each other following the staggered grid approach. This ensures stability and prevents oscillations in pressure. It allows to treat almost all the Reynolds number ranges for all speeds and viscosities. The disadvantages appear when we want to treat more complex geometries or if a generalized curvilinear formulation of the conservation equations is considered. Too many interpolations have to be done and accuracy is then lost. In order to overcome these problems, we use here a similar algorithm in time and a Rhie and Chow interpolation (1983) of the collocated variables and essentially the velocities at the interface. The Rhie and Chow interpolation of the velocities at the finite volume interfaces allows to have no oscillations of the pressure without checkerboard effects and to stabilize all the algorithm. In a first predictor step, fluxes at the interfaces of the finite volumes are then computed using 2nd and 3rd order shock capturing schemes of MUSCL/TVD or Van Leer type, and the orthogonal stress components are treated implicitly while cross viscous/diffusion terms are treated explicitly. Pentadiagonal linear systems are solved in each geometrical direction (the so

  18. Enhanced propylene production in FCC by novel catalytic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, C.P.; Harris, D.; Xu, M.; Fu, J. [BASF Catalyst LLC, Iselin, NJ (United States)

    2007-07-01

    Fluid catalytic cracking is expected to increasingly supply the additional incremental requirements for propylene. The most efficient route to increase propylene yield from an FCC unit is through the use of medium pore zeolites such as ZSM-5. ZSM-5 zeolite cracks near linear olefins in the gasoline range to LPG olefins such as propylene and butylenes. This paper will describe catalytic approaches to increase gasoline range olefins and the chemistry of ZSM-5 to crack those olefins. The paper will also describe novel catalytic materials designed to increase propylene. (orig.)

  19. Examination of the SG tube fatigue cracking at Fessenheim unit no.2 of EDF

    International Nuclear Information System (INIS)

    In February 2008, a primary-to-secondary leak occurred at Fessenheim Unit No.2 on a steam generator. A circumferential fatigue crack was observed at the upper tube support plate level of the R12C62 tube although the stability ratio evaluation performed to take into account some prior international events, concluded that this tube had no risk of fluid-elastic instability. A new tube pull process was developed and performed by AREVA in 2011 just before the SG replacement. The extraction at the uppermost TSP elevation was a first occurrence in the French EDF PWR. Destructive examinations were carried out in the EDF hot laboratory of CEIDRE/Chinon in order to characterize damage mechanisms at the initiation and propagation stage. The document relates the major results of laboratory examinations leading us to exclude the fluid-elastic instability scenario as previously reported in North-Anna (1987) and Mihama (1991) tube rupture incidents. Results analysis with particular focus on the fracture surface description using Scanning Electron microscopy observations and metallurgical investigations provide new elements concerning the aggravating factors of fatigue damage. Fracture surface investigations reveal that the circumferential crack was due to high cycle fatigue with a very low stress intensity factor. Some aggravating factors like intergranular corrosion appeared to be critical for the fatigue cracking initiation stage. The deterioration was also largely promoted by the lack of tube support at the Anti-Vibration Bars

  20. Influence of crystallite size and shape of zeolite ZSM-22 on its activity and selectivity in the catalytic cracking of n-octane

    Energy Technology Data Exchange (ETDEWEB)

    Bager, F.; Ernst, S. [Kaiserslautern Univ. (Germany). Dept. of Chemistry, Chemical Technology

    2013-11-01

    Light olefins belong to the major building blocks for the petrochemical industry, particularly for the production of polymers. It has become necessary to increase the production of light olefins specifically in the case for propene with so called 'on-purpose propene' technologies. One possible route is to increase the amount of propene that can be obtained from Fluid Catalytic Cracking (FCC) by optimizing the catalyst through introducing new additives, which offer a high selectivity to propene. Zeolite ZSM-22 samples with different crystallite sizes and morphologies have been synthesized via hydrothermal syntheses and characterized by powder X-Ray diffraction, nitrogen physisorption, atomic absorption spectroscopy, scanning electron microscopy and solid-state NMR spectroscopy. The zeolites in the Broensted-acid form have been tested as catalysts in the catalytic cracking of n-octane as a model hydrocarbon. Clear influences of the crystallite size on the deactivation behavior have been observed. Larger crystals of zeolite ZSM-22 produce an increased amount of coke deposits resulting in a faster deactivation of the catalyst. The experimental results suggest that there is probably some influence of pore diffusion on the catalytic activity of the ZSM-22 sample with the large crystallite size. However a noticeable influence on the general product distribution could not be observed. (orig.)

  1. Corrosion rate of steel embedded in blended Portland and fluid catalytic cracking catalyst residue (FC3R cement mortars

    Directory of Open Access Journals (Sweden)

    Payá, J.

    2008-12-01

    Full Text Available This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20% spent fluid catalytic cracking catalyst residue (FC3R, with a variable (0.3-0.7 water/binder (w/b ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc variable (0,3-0,7, en los que parte del cemento (0-20% se sustituyó por catalizador de craqueo usado (FC3R. Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100% y dos concentraciones de CO2 (5 y 100%. La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R.

  2. Retrofitting the Structure of the Catalytic Cracking Reactor, from Petrobrazi Refinery, Ploieşti by Transforming the Steel Structure into a Moment Resisting Frame and Enhancing the Damping of the Structure by Means of Viscous Dampers

    Directory of Open Access Journals (Sweden)

    Vasilescu Ionuţ

    2015-12-01

    Full Text Available The present paper presents the structural and seismic retrofit solution for the structure of the Catalytic Cracking Reactor, from Petrobrazi Refinery, Ploiești, Romania. The spatial truss type steel structure was designed and built during 1965-1968, following United States codes of that time. The capacity of the reactor is intended to be increased, thus its weight increases by approx. 43%. The retrofit solution had to take into consideration many criteria, not only technical, but also technological. After analyzing several possibilities, it was decided that the only feasible solution in order to fulfill all these requirements was to significantly increase the viscous damping of the structure – by introducing viscous dampers in its diagonals, accompanied by the strengthening of steel structure and changing the structural system into a moment resisting frame.

  3. Characterization of deactivated catalytic cracking catalyst and evaluation as absorbent material; Caracterizacao de catalisador de craqueamento catalitico desativado e avaliacao como material adsorvente

    Energy Technology Data Exchange (ETDEWEB)

    Valt, R.B.G.; Kaminari, N.M.S.; Cordeiro, B.; Ponte, M.J.J.S.; Ponte, H.A. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

    2010-07-01

    One of the main uses of catalysts in the petroleum industry is in step catalytic cracking, which after use and regeneration cycles generates large quantities of waste material. In this research the deactivated FCC catalyst was characterized before and after the electrokinetic remediation process, in order to assess the change of its structure and possible adsorptive capacity. Analyses of X-Ray Fluorescence Spectroscopy, Scanning Electron Microscopy and BET surface area measurement were performed. The analysis showed no structural change due to the process employed and that electrokinetic remediation has recovered 42% of adsorption capacity of the material, by removing about 89% of heavy metals adhered initially in the catalyst surface. (author)

  4. HZSM-5/MCM-41 composite molecular sieves for the catalytic cracking of endothermic hydrocarbon fuels: nano-ZSM-5 zeolites as the source

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Yu; Jiao, Qingze; Li, Hansheng, E-mail: hanshengli@bit.edu.cn; Wu, Qin; Zhao, Yun; Sun, Kening, E-mail: sunkn@bit.edu.cn [Beijing Institute of Technology, School of Chemical Engineering and the Environment (China)

    2014-12-15

    A series of HZSM-5/MCM-41 composite molecular sieves (HZM-Ns (x)) were prepared by employing nano-ZSM-5 zeolites with the SiO{sub 2}/Al{sub 2}O{sub 3} ratios (x) of 50, 100 and 150 as the source. These materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, N{sub 2} adsorption–desorption measurement, and NH{sub 3} temperature-programmed desorption. The catalytic cracking of endothermic hydrocarbon fuels over the HZM-Ns with n-decane as model was evaluated at atmospheric pressure and 500 °C. The effect of the parent zeolite, mesopore and SiO{sub 2}/Al{sub 2}O{sub 3} ratio on the structure, acidity, and catalytic performance of HZM-Ns was investigated. The HZM-Ns exhibited a skeletal matrix with nano-sized HZSM-5 particles (200–300 nm) with a controllable acidity well dispersed in and microporous–mesoporous hierarchical pores. The mesoporous structure improved the diffusion of the reactants and products in the pores, and the HZSM-5 nanoparticles uniformly dispersed in the MCM-41 matrix supplied a proper acidity, shorter channels, and a higher specific surface area for reaction. These resulted in a high catalytic activity, a high selectivity to light olefins and a long lifetime for n-decane catalytic cracking. The HZM-N (150) exhibited the excellent conversion, a high selectivity to light olefins and a long lifetime due to low diffusion resistance, high specific surface area, and appropriate acid distribution and strength, with the increasing SiO{sub 2}/Al{sub 2}O{sub 3} ratio.

  5. Production of filamentous carbon and H{sub 2} by solarthermal catalytic cracking of CH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, V.; Kuvshinov, G. [Boreskov Inst. of Catalysis (Russian Federation); Reller, A. [Hamburg Univ., Hamburg (Germany); Steinfeld, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The catalytic thermal decomposition of methane has been experimentally studied using high-temperature solar process heat. Nickel catalyst particles, fluidized in methane, were directly irradiated at the PSI solar furnace. Carbon deposition consisted of randomly interlaced filaments that grew as fibers and hollow nanotubes (of approx. 30 nm diameter) originating at each catalytic particle. (author) 4 figs., 7 refs.

  6. The process greasoline {sup registered}. Catalytic cracking of used vegetable oils and vegetable products; Das greasoline {sup registered} -Verfahren. Katalytisches Cracken von gebrauchten Pflanzenoelen und Pflanzenprodukten

    Energy Technology Data Exchange (ETDEWEB)

    Danzig, Joachim; Fastabend, Anna; Greve, Anna; Heil, Volker; Juricev-Spiric, Marko; Kraft, Axel; Krzanowski, Marcin; Meller, Karl; Menne, Andreas; Unger, Christoph; Urban, Wolfgang [Fraunhofer-Institut fuer Umwelt-, Sicherheits- und Energietechnik UMSICHT, Oberhausen (Germany)

    2009-12-15

    Converting bio-based waste oils and fats as well as non-edible plant oils into oxygen-free components for quality aviation, shipping and automotive fuels represents a promising option to use these materials. Catalytic cracking over microporous and mesoporous catalysts like activated carbon offers a suitable process of considerable commercial and ecological potential. Moreover, this technology can be applied in order to produce high-caloric fuel gases like bio-based LPG. For example, these gases could be used for upgrading bio-methane into true bio-based synthetic natural gas without adding fossil components. Such a mixture would be ready to be fed into natural gas pipelines. In the future, used bio-hydraulic-oils could be collected and used as biofuels feedstock. Conversion of bio-hydraulic-oils as model substances resulted in organic liquid product yields of up to 64 wt.-%. Catalytic cracking of Jatropha Curcas-oil revealed the catalyst's usage time to be as important as the reaction temperature for optimising fuel gas production. (orig.)

  7. Analysis of cracked core spray injection line piping from the Quad Cities Units 1 and 2 boiling water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Diercks, D.R.

    1983-12-01

    Elbow assemblies and adjacent piping from the loops A and B core spray injection lines of Quad Cities Units 1 and 2 Boiling Water Reactors have been examined in order to determine the nature and causes of coolant leakages and flaw indications detected during hydrostatic tests and subsequent ultrasonic inspections. The elbow assemblies were found to contain multiple intergranular cracks in the weld heat-affected zones. The cracking was predominantly axial in orientation in the forged elbow and wedge components, whereas mixed axial and circumferential cracking was seen in the wrought piping pieces. In at least two instances, axial cracks completely penetrated the circumferential weld joining adjacent components. Based upon the observations made in the present study, the failures were attributed to intergranular stress corrosion cracking caused by the weld-induced sensitized microstructure and residual stresses present; dissolved oxygen in the reactor coolant apparently served as the corrosive species. The predominantly axial orientation of the cracks present in the forged components is believed to be related to the banded microstructure present in these components. The metallographic studies reported are supplemented by x-radiography, chemical analysis and mechanical test results, determinations of the degree of sensitization present, and measurements of weld metal delta ferrite content.

  8. Relationship between structure and catalytic performance of dealuminated Y zeolites

    International Nuclear Information System (INIS)

    Dealuminated Y zeolites which have been prepared by hydrothermal and chemical treatments show differences in catalytic performance when tested fresh; however, these differences disappear after the zeolites have been steamed. The catalytic behavior of fresh and steamed zeolites is directly related to zeolite structural and chemical characteristics. Such characteristics determine the strength and density of acid sites for catalytic cracking. Dealuminated zeolites were characterized using x-ray diffraction, porosimetry, solid-state NMR and elemental analysis. Hexadecane cracking was used as a probe reaction to determine catalytic properties. Cracking activity was found to be proportional to total aluminum content in the zeolite. Product selectivity was dependent on unit cell size, presence of extra framework alumina and spatial distribution of active sites. The results from this study elucidate the role that zeolite structure plays in determining catalytic performance

  9. Hexene catalytic cracking over 30% sapo-34 catalyst for propylene maximization: influence of reaction conditions and reaction pathway exploration

    Directory of Open Access Journals (Sweden)

    Z. Nawaz

    2009-12-01

    Full Text Available Higher olefins are produced as a by product in a number of refinery processes and are one of the potential raw materials to produce propylene. In the present study, FCC model feed compound was considered to explore the olefin cracking features and options to enhance propylene using 30% SAPO-34 zeolite as catalyst in a micro-reactor. The superior selectivity of propylene (73 wt% and higher total olefin selectivity was obtained over 30% SAPO-34 catalyst than over Y or ZSM-5 zeolite catalysts. The thermodynamical constraints were found to be relatively less serious in the case of 1-hexene conversion. Most of the 1-hexene follows a direct cracking pathway to give two propylene molecules, due to weak acid sites and better diffusion opportunities. The higher temperature and short residence time could also suppress the hydrogen transfer reactions. From OPE (olefins performance envelop the products were classified as primary, secondary, or both. Iso-hexene (2-methyl-2-pentene cracking was also analyzed in order to justify a shape selective effect of the SAPO-34 catalyst. A detailed integrated reaction network together with an associated mechanism was proposed and discussed in detail for their fundamental importance in understanding the olefin cracking processes over SAPO-34.

  10. Gas chromatographic-mass spectrometric characterization of all acyclic C5-C7 alkenes from fluid catalytic cracked gasoline using polydimethylsiloxane and squalane stationary phases.

    Science.gov (United States)

    Soják, Ladislav; Addová, Gabriela; Kubinec, Róbert; Kraus, Angelika; Hu, Gengyuan

    2002-02-15

    Published retention indices of acyclic alkenes C5-C7 on squalane and polydimethylsiloxane as stationary phases were investigated, and reliable retention indices of alkenes from various sources were converted to separation systems used in a laboratory. Retention indices measured on available authentic commercial alkenes and on alkenic fraction of gasoline, published retention indices as well as means of GC-MS were used for verification of calculated retention indices. Retention of some gas chromatographic unseparated isomer pairs was obtained by mass spectrometric deconvolution using a specific single-ion monitoring. On the basis of these retention data, C5-C7 alkenes were identified and analyzed in the gasoline from fluid catalytic cracking. In the gasoline all 59 acyclic C5-C7 isomeric alkenes were determined at significantly different concentration levels.

  11. Percolation cooling of the Three Mile Island Unit 2 lower head by way of thermal cracking and gap formation

    DEFF Research Database (Denmark)

    Thomsen, K.L.

    2002-01-01

    Two partial models have been developed to elucidate the Three Mile Island Unit 2 lower head coolability by water percolation from above into the thermally cracking debris bed and into a gap between the debris and the wall The bulk permeability of the cracked top crust is estimated based on simple...... fracture mechanics and application of Poiseuille's law to the fractures. The gap is considered as an abstraction representing an initially rugged interface, which probably expanded by thermal deformation and cracking in connection with the water ingress. The coupled flow and heat conduction problem...... for the top crust is solved in slab geometry based on the I two-phase Darcy equations together with quasi-steady mass and energy conservation equations. The resulting water penetration depth is in good agreement with the depth of the so-called loose debris bed The lower-head and bottom-crust problem...

  12. Catalytic reactions of C4 hydrocarbons on the fluid catalytic cracking catalyst%C4烃类在催化裂化催化剂上催化转化反应的研究

    Institute of Scientific and Technical Information of China (English)

    闫平祥; 孟祥海; 徐春明; 高金森

    2008-01-01

    The catalytic reactions of C4 hydrocarbons on a fluid catalytic cracking (FCC) catalyst were studied in a confined fluidized bed reactor. The effect of reaction temperature and space velocity on product yields and distribution was investigated. The results show that the FCC catalyst has the good performance of aromatization and cracking of C4 hydrocarbons and can be used to produce propylene and aromatics under the suitable reaction conditions. It is mainly the butylene in the C4 hydrocarbons that undergoes catalytic reactions over the FCC catalyst and butane is hard to convert. Low reaction temperature favors the production of aromatics, while high reaction temperature favors the production of propylene. Low space velocity is beneficial to promote the conversion of butylene and the production of both aromatics and propylene. According to the bimolecular mechanism and reaction results, the reaction network for the catalytic reactions of C4 hydrocarbons on the FCC catalyst is proposed. The analysis on the this reaction mechanism indicates that the main reason of resulting in the lower yields of ethylene and propylene could be the poor secondary cracking performances of C5 and C6 olefins formed in the catalytic conversion of C4 hydrocarbons on the FCC catalyst.%利用小型固定流化床实验装置,对C4烃类在催化裂化催化剂上催化转化反应规律进行了实验研究,考察了不同反应温度及空速对C4烃类催化转化反应的产物分布和组成的影响.实验结果表明,催化裂化催化剂对C4烃类具有一定芳构化和裂化性能,在适宜的反应条件下,可增产芳烃和丙烯;在C4烃类催化转化过程中,丁烯是主要的反应物,而丁烷几乎不反应;低反应温度有利于增产芳烃,高反应温度有利于增产丙烯.较低的空速对增产芳烃和丙烯都有利.根据双分子反应机理和反应结果 ,建立了C4烃类在催化裂化催化剂上催化转化过程的反应网络.对C4烃类催化转化

  13. Large Mesopore Generation in an Amorphous Silica-Alumina by Controlling the Pore Size with the Gel Skeletal Reinforcement and Its Application to Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Hiroyuki Nasu

    2012-09-01

    Full Text Available Tetraethoxy orthosilicate (TEOS was used not only as a precursor of silica, but also as an agent which reinforces the skeleton of silica-gel to prepare an aerogel and resultant silica and silica-alumina with large pore size and pore volume. In this gel skeletal reinforcement, the strength of silica aerogel skeleton was enhanced by aging with TEOS/2-propanol mixed solution to prevent the shrink of the pores. When silica aerogel was reinforced by TEOS solution, the pore diameter and pore volume of calcined silica could be controlled by the amount of TEOS solution and reached 30 nm and 3.1 cm3/g. The results from N2 adsorption measurement indicated that most of pores for this silica consisted of mesopores. Silica-alumina was prepared by the impregnation of an aluminum tri-sec-butoxide/2-butanol solution with obtained silica. Mixed catalysts were prepared by the combination of β-zeolite (26 wt% and prepared silica-aluminas with large mesopore (58 wt% and subsequently the effects of their pore sizes on the catalytic activity and the product selectivity were investigated in catalytic cracking of n-dodecane at 500 °C. The mixed catalysts exhibited not only comparable activity to that for single zeolite, but also unique selectivity where larger amounts of branched products were formed.

  14. Synthesis,characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; DOU Tao; ZHANG Ying; LI Yuping; WANG Shan; SUN Famin

    2007-01-01

    Mesoporous aluminosilicate MCM-48 containing zeolite secondary building units in the pore wall has been synthesized in alkaline media with a two-step procedure.The aluminosilicate precursors comprising zeolite secondary building units were first synthesized by carefully controlling reaction conditions and then were assembled using cotemplates of geminisurfactant [C18H37N(CH3)2(CH2)3-N(CH3)2C18H37]2+ (18-3-18) and triethanolamine (TEA).X-ray Diffraction (XRD) patterns of the as-made samples indicated that highly ordered mesostmctured MCM-48 was formed.Transmission Electron Microscopy (TEM) images further verified the formation of MCM-48 with uniform cubic pore channel system having the pore opening diameter of about 25 A.Compared with the conventionally synthesized MCM-48,the as-synthesized MCM-48 sample showed an adsorption band at 520-600 cm-1 in its FT-IR spectrum,which was assigned to five-membered ring vibration from zeolite structure.This suggested the presence of zeolite building units in the pore wall.N2 adsorption data showed that the material had a much higher specific surface area (1 200 m2/g)than the conventional MCM-48(1 100 m2/g).Finally,the catalytic performance of the as-made MCM-48 was evaluated by hydrogenation dealkylation reaction of heavy aromatic hydrocarbons.Catalytic results showed that the as-made MCM-48 catalyst exhibited higher conversion than the conventional MCM-48 catalyst.The as-made mesostructured MCM-48 may have a potential catalytic application in the conversion of bulky molecules.

  15. CRACKING OF PALM OIL TO PRODUCE OLEOCHEMICALS

    OpenAIRE

    Nwokedi I.C.; ,Okoye, C.C.

    2015-01-01

    The FTIR and GC - MS tests are necessary for identification of oleochemicals produced via cracking. In this research, thermal cracking (without catalyst) and catalytic cracking of palm oil were carried out in a batch reactor. The thermal cracking was performed at temperatures of 700 o C to 900 o C at a time of 30 to 150 minutes while the catalytic cracking was done at temperatures of 100 o C to 400 o C, time of 30 ...

  16. Stress corrosion cracking of CRD stub tube joint and repair at Hamaoka Unit 1

    International Nuclear Information System (INIS)

    On November 9, 2001, after the pipe rupture incident of the Residual Heat Removal system (RHR), plant personnel found the leak from the bottom of the Reactor Pressure Vessel (RPV). Afterwards, with underwater visual inspection, plant personnel found an axial cracking on one of the stub tube's weldments. In order to join the Nickel base material (Alloy 600) stub tube, a similar weld material (Alloy 182) is deposited to the low-alloy metal (LAS) vessel. From the examination of a boat sample it was found that the cracking in the Alloy 182 weld metal was due to interdendric (intergranular) stress corrosion cracking, which had progressed into the Alloy 600. Residual and applied stress during an in-service analysis explained that the location could have high tensile stress (330MPa and over). In order to repair cracking, a replacement method was applied. The stub tube and weld joint including the crack area was completely removed, and a new stub tube consisting of high corrosion resisted material was installed and welded. Remote automatic equipment was applied during the replacement process because of the high radiation environment. After inspecting the rest of the 88 stub tube's joints, there were no indications of any further problems. For higher reliability, the application of laser-peening technique is being examined. (author)

  17. Major Problems Related with Operation of Catalytic Reforming Units and Countermeasures

    Institute of Scientific and Technical Information of China (English)

    Zhou Jianhua

    2006-01-01

    @@ Currently the catalytic reforming units are playing an increasingly important role for gasoline quality upgrading, increased production of high add-value aromatic compounds and supply of cheap hydrogen resources. The high proportion of FCC gasoline in China' s automotive gasoline pool has led to a quite significant gap in gasoline quality as compared to the demand of World Fuel Charter and even to the new Chinese standards for unleaded automotive gasoline. According to the statistical data, the ratio of FCC naphtha in the gasoline pool is 35% in the US and 27% in EU, whereas that number is 75% in China's gasoline pool. The share of reformate and other high-quality gasoline components in the gasoline pool is 65% in the US and 73% in EU, whereas that number is merely 14% in China's gasoline pool along with a definite share of low-octane (straight-run) gasoline. Therefore, devoting major efforts to the development of catalytic reforming technology to increase the output of high-octane, lowolefin and low-sulfur reformer gasoline component is an effective avenue for gasoline quality upgrading along with increased production of high add-value aromatics and cheap hydrogen.

  18. Catalytic cracking of the C5+ fraction of natural gasoline using HZSM-5 zeolite; Craqueamento catalitico de uma fracao de C5+ do GN utilizando a zeolita HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Marcelo J.B.; Silva, Antonio O.S. [Rio Grande do Norte Univ., Natal, RN (Brazil). Dept. de Engenharia Quimica]. E-mail: marcelojbs@yahoo.com.br; Fernandes Junior, Valter J.; Araujo, Antonio S. [Rio Grande do Norte Univ., Natal, RN (Brazil). Dept. de Quimica

    2003-07-01

    In this work was realized a study of the catalytic cracking of the C5+ fraction from Polo of Guamare (RN) over acid the HZSM-5 zeolite. The ZSM-5 zeolite was synthesized by hydrothermal crystallization with subsequent, filtering, washing and calcination to obtain the sodium form (NaZSM-5). To obtain the acidic form (HZSM-5), the NaZSM-5 zeolite was submitted to ion exchange with ammonium chloride solution. The obtained material was characterized by x ray diffraction, infrared spectroscopy, atomic absorption spectrophotometry and acidity via TG/DTG. The catalytic cracking reactions of the C5+ feedstock were performed in a fixed bed continuous flow reactor and the reaction products were analyzed in a gas chromatography coupled in a mass spectrometer (GC/MS). The obtained result shown the formation of high aggregate value hydrocarbons as: LPG (propane and butane) and industrial gas (ethane and ethene). (author)

  19. Investigation of CO2 capture in fluid catalytic cracking process%催化裂化实现CO2捕集的技术探讨

    Institute of Scientific and Technical Information of China (English)

    李秋芝; 陈曼桥; 孟凡东; 王龙延

    2012-01-01

    论述了4种碳捕集方法,即燃烧前捕集、氧燃烧捕集、燃烧后捕集和化学链燃烧捕集,得出氧燃烧捕集是比较适合于催化裂化实现CO2捕集的技术.同时,讨论了氧燃烧对再生器效率、旋风分离器效率以及取热器负荷的影响.%Four methods of carbon capture and sequestration are described in this study, including pre-combustion capture, post-combustion capture, oxy-fuel combustion capture and chemical looping combustion capture. Among all of these methods, it is concluded that oxy-fuel combustion capture is a suitable method for fluid-catalytic-cracking CO2 capture. Furthermore, the effect of oxy-fuel combustion on the effectiveness of regenerator and cyclone separator, and the load of catalyst cooler are discussed.

  20. 重油催化裂解汽柴油二次裂解性能研究%Secondary Cracking of Gasoline and Diesel from Heavy Oil Catalytic Pyrolysis

    Institute of Scientific and Technical Information of China (English)

    刘植昌; 孟祥海; 徐春明; 高金森

    2007-01-01

    This paper investigated the secondary cracking of gasoline and diesel from the catalytic pyrolysis of Daqing atmospheric residue on catalyst CEP-1 in a fluidized bed reactor.The results show that the secondary cracking reactivity of gasoline and diesel is poor, and the yield of total light olefins is only about 10% (by mass).As reaction temperature increases, ethylene yield increases, butylene yield decreases, and propylene yield shows a maximum.The optimal reaction temperature is about 670 ℃ for the production of light olefins.With the enhancement of catalyst-to-oil mass ratio and steam-to-oil mass ratio, the yields of light olefins increase to some extent.About 6.30% of the mass of total aromatic rings is converted by secondary cracking, indicating that aromatic hydrocarbons are not easy to undergo ring-opening reactions under the present experimental conditions.

  1. 40 CFR 63.1566 - What are my requirements for organic HAP emissions from catalytic reforming units?

    Science.gov (United States)

    2010-07-01

    ... process heater with a design heat input capacity of 44 MW or greater or a boiler or process heater in... Tables 15 and 16 of this subpart apply to emissions from catalytic reforming unit process vents... from process vents during depressuring and purging operations when the reactor vent pressure is...

  2. Crack dancing in the United Kingdom: apropos a video case presentation.

    Science.gov (United States)

    Kamath, Shankar; Bajaj, Nin

    2007-06-15

    We report an adult patient presenting with choreiform movements 4 days after a large intravenous dose of cocaine. These movements were transitory and they normalized a week after admission. We believe this to be the first video case of acute chorea secondary to cocaine--a phenomenon popularly known as "crack dancing. " Cocaine abuse is associated with a wide range of movement disorders, including dystonia and exacerbation of Tourette's syndrome, multifocal tics, opsoclonus-myoclonus, choreiform movements, and stereotyped behavior known as "punding." Transient choreiform movements with a typical duration of 2 to 6 days are recognized by cocaine abusers themselves as crack dancing, but are infrequently reported. We present a video report of a patient with cocaine dependency and choreiform movements that normalized within a week of admission. PMID:17415801

  3. Single fibre and multifibre unit cell analysis of strength and cracking of unidirectional composites

    DEFF Research Database (Denmark)

    Wang, H.W.; Zhou, H.W.; Mishnaevsky, Leon;

    2009-01-01

    Numerical simulations of damage evolution in composites reinforced with single and multifibre are presented. Several types of unit cell models are considered: single fibre unit cell, multiple fibre unit cell with one and several damageable sections per fibres, unit cells with homogeneous and inho...

  4. Ni/凹凸棒石催化裂解生物质焦油组分甲苯%CATALYTIC CRACKING OF BIOMASS TAR ON Ni/PALYGORSKITE

    Institute of Scientific and Technical Information of China (English)

    陈天虎; 施培超; 张先龙; 宋磊; 石莹; 李金虎

    2011-01-01

    Large surface area palygorskite supported with Ni catalyst was prepared by equal volume impregnation. Catalytic cracking experiments on biomass tar were made on Ni/palygorskite with toluene as a model compound in the presence of CO2. The samples were characterized by XRD and TEM. The impacts of reaction temperature, amount of Ni and amount of CO2 on H2 yield and carbon deposit were researched in a temperature-ontrolling stove. The results showed that the H2 yield and amount of carbon deposit decreased with incresed of CO2 content and reaction temperature. However, the H2 yield increased.%以大比表面积的天然纳米矿物凹凸棒石为载体,利用等体积浸渍法制备出Ni/凹凸棒石催化剂.以甲苯为生物质焦油的模型化合物,在CO2气氛下研究Ni/凹凸棒石催化剂对甲苯的催化裂解性能.采用XRD、TEM等分析手段对制备的催化剂进行表征,然后在气-固相催化实验装置中考查CO2浓度、反应温度和Ni担载量对H2产量和积碳量的影响.结果表明:随着CO2浓度和反应温度的升高,H2产量呈下降趋势;增加Ni担载量,有利于提高H2产量;提高CO2浓度和反应温度,积碳量减小.

  5. Catalytic upgrading of biomass pyrolysis vapours using Faujasite zeolite catalysts

    NARCIS (Netherlands)

    Nguyen, T.S.; Zabeti, M.; Lefferts, L.; Brem, G.; Seshan, K.

    2012-01-01

    Bio-oil produced via fast pyrolysis of biomass has the potential to be processed in a FCC (fluid catalytic cracking) unit to generate liquid fuel. However, this oil requires a significant upgrade to become an acceptable feedstock for refinery plants due to its high oxygen content. One promising rout

  6. Secondary side cracking at Saint-Laurent unit B1: investigations, operating chemistry and corrosion tests

    International Nuclear Information System (INIS)

    Among the similar steam generators (SG) in EDF plants (equipped with mill annealed Alloy 600, drilled tube-support plates TSP), one of the SG of SAINT-LAURENT B1 was found particularly affected by cracking at TSP level. Eddy current indications lead to pull one tube after 30 000 h of operation: investigations revealed that corrosion was involved. In 1991, after 58 000 h, numerous indications with axial probe were beyond the recording threshold. A few heats were concerned, the examination of 11 pulled tubes evidenced an important axial intergranular stress corrosion cracking (IGSCC), with bands of intergranular attack (IGA) in front of the edge of TSPs. This investigation has qualified a new probe (STL 10). A new plugging criterion was also defined. In the same time, the results from hideout return tests and the operating chemistry were examined. They did not provide a satisfactory explanation of the observed damage. The degradations have affected only one out of three SG and the pH-calculations using MULTEQ code have shown that the environment in restricted-flow areas has not always been strongly alkaline (pH270: 5.7 to 10.2). Moreover, pH-values were decreasing after successive hideout return shutdowns. Corrosion tests were then performed in laboratory conditions (sodium hydroxide, 350 deg C) in order to study the sensitivity of the pulled tubes. They demonstrated the greatest sensitivity to cracking of these tubes, among various mill-annealed tubes in Alloy 600. The worst behaviour in caustic environment of SAINT-LAURENT tubes is apparently not connected with their metallurgical structure; moreover, they are not sensitized (no intergranular chromium depletion). The sensitivity in caustic environment seems to be in accordance with a low value of the yield stress. Studies are still in progress in order to examine if it is the right explanation for the sensitivity of Saint-Laurent tubes (the composition at the grain boundaries is also investigated...). The knowledge

  7. 静电分离催化裂化油浆中固体颗粒及其组成的研究%Removing Solid Particles in Fluid Catalytic Cracking Slurry by Electrostatic Separation and Their Composition

    Institute of Scientific and Technical Information of China (English)

    赵娜; 于传瑞; 赵波; 陈坤; 郭爱军; 王宗贤

    2015-01-01

    采用自制的静电分离装置,对某重油催化裂化装置外甩的催化裂化油浆(FCCS)进行静电分离实验。考察分离时间、温度、填料粒径、电场强度及分离级数对静电脱除效率的影响,并采用SEM,EDS,XRD等方法对固体颗粒进行表征。实验结果表明,静电脱除效率,随静电分离时间的延长先增大后趋于稳定,随温度的升高而增大,随填料粒径的减小而增大,随电场强度的增加先增大后有所降低;适宜的分离条件为:分离时间25~30 min、温度140~160℃、填料粒径2.0~2.5 mm、电场强度3.5 kV/cm,在此条件下经三级静电分离可使静电脱除效率最高达到99%,FCCS中的固体颗粒含量由4200 mg/L降至50 mg/L以下;FCCS中的固体颗粒主要由催化剂细粉、焦粉和金属锑组成。%The electrostatic separation of fluid catalytic cracking slurry(FCCS) from a heavy oil catalytic cracking unit was carried out in a self-made experimental installation. The influences of processing time,temperature,packing diameter,separation stages and electric field intensity on the electrostatic removal efficiency were investigated. The solid particles in FCCS were characterized by means of SEM,EDS and XRD. The experimental results showed that,the electrostatic removal efficiency firstly increased and then stabilized with prolonging the processing time,increased with the temperature rise,increased with the decrease of the packing diameter,and increased and then decreased with the increase of the electric field intensity. Under the appropriate conditions of processing time 25-30 min,temperature 140-160℃,packing diameter 2.0-2.5 mm and electric field intensity 3.5 kV/cm,through three-stage of electrostatic separation,the electrostatic removal efficiency reached 99% and the content of the solid particles in FCCS lowered from 4 200 mg/L to less than 50 mg/L. The solid particles in FCCS consisted of catalyst powder

  8. Catalytic Cracking Conversion of Tar Component in High Temperature Coal Gas%高温煤气中焦油组分的催化裂解

    Institute of Scientific and Technical Information of China (English)

    赵国靖; 李海涛; 豆斌林; 沙兴中

    2001-01-01

    在固定床反应器条件下对焦油组分(以1-甲基萘作为焦油的模型化合物)进行了催化裂解研究,选择镍基催化剂、5A分子筛、CaO催化剂、矾土和石英砂等5种催化剂为焦油组分裂解催化剂。研究表明此5种催化剂对1-甲基萘的裂解都具有催化活性,10h反应时间内,5A分子筛和Ni基催化剂对1-甲基萘的转化率为100%,CaO催化剂、矾土和石英砂对1-甲基萘的转化率则较低。同时研究了温度对Ni-3催化剂和5A分子筛的转化率的影响。为了进行比较也测试了Ni-3催化剂对苯的转化率,总包一级反应线性回归出催化剂在250~500℃的裂解活化能为22.17kJ/mol。%The tar decomposition activities of five catalysts including Nibased catalyst, alumina, 5A molecular sieve, CaO catalyst, quartz sand catalysts are compared in a fixed bed catalytic reactor. 1-methylnaphthalene is used as a tar model compound. All these catalysts show to be active and useful for tar cracking reactions, deactivations of Ni based and 5A molecular sieve catalyst are not found within 10 h reaction time with space velocity of 3 000 h-1 at temperature of 550 ℃. Especially, with increasing temperature, the conversion of 1-methylnaphthalene is improved. At same time, Ni-3 catalyst is found to be effective for benzene conversion at 550 ℃ and 650 ℃. Using a simple first-order kinetic model for the overall reaction, an apparent activation energies (22.17 kJ/mol for Ni-3 catalyst) is obtained at 250~500 ℃.

  9. Synthesis of vegetable oils cracking catalyst and catalytic properties%植物油脂裂解催化剂的合成及其催化性能研究

    Institute of Scientific and Technical Information of China (English)

    张爱华; 肖志红; 张良波; 皮兵; 李洋; 李昌珠

    2014-01-01

    选用典型的高含油光皮树果实,采用等体积浸渍法制备固体碱催化剂KF/CaO催化裂解制备生物燃料油,并通过FTIR、XRD、SEM、CO2-TPD等对催化剂进行表征。对催化裂解后气相产率、液体油产率和固相产率的变化来验证催化剂的催化性能,考察催化剂用量、裂解反应时间和裂解反应温度对产物产率的影响。实验结果表明,在催化剂用量1.2%、反应温度500℃、反应时间为45 min的条件下,实测生物燃料油产率可以达到82.56%。%Using typical high oil Cornus wisoniana fruit of woody plants as the research object,and KF/CaO solid base catalyst was prepared by impregnation,obtained bio-fuel by the catalytic cracking reaction. The solid base catalyst was characterized by the analysis of SEM,XRD,FTIR and CO2-TPD. It evaluated the catalytic activity of KF/CaO through the change of the liquid oil yield,the yield of the solid phase and the gas phase yield in cracking reaction. The conditions of the cracking reaction were studied including amount of catalyst,reaction time and cracking reaction temperature. The results show:82. 56%yield was obtained under optimized conditions as:1. 2% of catalyst,the 500 ℃ of reaction temperature and 45 min of the reaction time.

  10. Three-dimensional simulation and modeling of a catalytic cracking fluidized bed reactor - cluster formation; Modelagem e simulacao tridimensional de um reator de craqueamento catalitico em leito fluidizado - formacao de clusters

    Energy Technology Data Exchange (ETDEWEB)

    Georg, Ivan Carlos; Maliska, Clovis Raimundo [Santa Catarina Univ., Florianopolis, SC (Brazil). Programa de Pos-graduacao em Engenharia Mecanica. Lab. de Simulacao Numerica em Mecanica dos Fluidos e Transferencia de Calor]. E-mail: ivan@sinmec.ufsc; maliska@sinmec.ufsc.br; Porto, Luismar Marques [Santa Catarina Univ., Florianopolis, SC (Brazil). Programa de Pos-graduacao em Engenharia Quimica e Alimentos. Lab. de Tecnologias Integradas]. E-mail: luismar@enq.ufsc.br

    2003-07-01

    Fluid catalytic cracking (FCC) is an industrial process that converts heavy hydrocarbons to lower molecular-weight products that are more profit. A multiphase model are developed to describe de gas-solid flow with a 3D high resolution grid, which have the finality to capture the meso-scale structures. This structures influence the transfer mechanisms of mass, momentum, energy and the rate of the reactions. The aim of this work is to present numerical results to demonstrate that the fluid dynamic model suggested here can capture the clusters of particles. (author)

  11. 40 CFR 60.105a - Monitoring of emissions and operations for fluid catalytic cracking units (FCCU) and fluid coking...

    Science.gov (United States)

    2010-07-01

    ... with the approved alternative for monitoring exhaust gas flow rate in 40 CFR 63.1573(a) of the National... the bag leak detection system using electronic or other means (e.g., using a strip chart recorder or...

  12. Improving crack counterbalanced sucker rod pump units; Ueberlegungen zum dynamischen Drehmomentenausgleich von Tiefpumpenantrieben

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, F. [Montanuniversitaet Leoben (Austria). Inst. fuer Konstruktionslehre

    1997-02-01

    Counterbalancing the torque at the gearbox, resulting from the load at the polished rod and the geometry of the unit, is still a significant design and operational problem. In this article well known crank-counterbalanced units are briefly described and a new unit, with an additional crank counterbalance system, is introduced. The counterweights on the cranks always create a sinusoidal torque distribution over one cycle. Applying the arithmetic method of non linear regression to the torque distribution, which results from the load at the polished rod, a most closely matching sinussoidal curve can be calculated. This curve shows the optimum phase angle and counterweight torque value and therefore a quick adjustment of the counterweights can be made. With the same arithmetic method, phase angle and counterweight value of the additional crank counterbalance is established. A comparison between a conventional unit and one with an additional counterbalancesystem has shown, that in the second case, the acting gearbox torque is up to 50% lower than in the first case. This allows the use of smaller gearbox and prime mover. From the technical point of view the additional counterbalance system is an excellent development enabling the acting-gearbox torque to be reduced. System set-up requires only a simple computer program and careful operator implementation. (orig.) [Deutsch] Der Ausgleich des zyklisch schwankenden Antriebsdrehmomentes stellt fuer die Auslegung und den Betrieb von Tiefpumpenantrieben ein zentrales Problem dar. In der vorliegenden Arbeit werden einleitend die bekannten Antriebsbauarten mit dynamischem Drehmomentenausgleich beschrieben und eine neue Bauart mit zusaetzlichem Ausgleich vorgestellt. Die Lasten am Pferdekopf verursachen an der Kurbel (Getriebeausgang) ein Drehmoment, das als Bruttodrehmoment bezeichnet wird. Das Ausgleichsdrehmoment zur Verringerung des Bruttodrehmomentes ist jenes Moment an der Kurbel, das durch die rotierenden

  13. 正辛烷热裂化和催化裂化生成甲烷反应机理%Mechanism of methane formation in thermal and catalytic cracking of n-octane

    Institute of Scientific and Technical Information of China (English)

    李福超; 张久顺; 袁起民

    2014-01-01

    The thermal and catalytic cracking reactions of n-octane were carried out in a temperature range of 550~650℃ with low conversions ( x<15%) in a pulse micro-reactor over quartz and ZRP zeolite. Reaction mechanism of methane formation was analyzed. The results showed that ethylene, propylene and n-butylene were primary products and four paths contributed to methane formation in thermal cracking of n-octane. At 600 ℃, dehydrogenation of terminal C-H bond in the chain attacked by methyl radical led to methane production. Due to higher activation energy of cleavage of terminal C-C bond in octyl radical formed via dehydrogenation of central C-C bond, only methane can form at higher temperature. Protolytic cracking was predominant with relatively remarkable yield of normal paraffin in catalytic cracking of n-octane over ZRP zeolite. Methane was produced by protolytic cracking route as well. By comparison of methane formation between thermal and protolytic cracking, it revealed that methane formed through protolytic cracking below 600℃ while thermal cracking dominated the selectivity of methane at higher reaction temperatures.%采用脉冲微反装置,在反应温度为550~650℃,低转化率(小于15%)下,研究了正辛烷在石英砂和ZRP分子筛上的热裂化和催化裂化反应,分析了甲烷的生成机理。结果表明,正辛烷热裂化时,乙烯、丙烯和正丁烯是初始产物,甲烷由4种反应路径生成。当反应温度为600℃时,甲基自由基攻击碳链端部C-H键生成甲烷。中部C-H键脱氢形成的辛基自由基在端部C-C键断裂的活化能较高,仅在高温下生成甲烷。正辛烷在ZRP分子筛上主要发生质子化裂化反应,正构烷烃占有相当比重,甲烷由质子化裂化步骤生成。热裂化与质子化裂化对甲烷贡献的对比可知,当反应温度低于600℃时,甲烷由质子化裂化反应生成;在高温下,热裂化反应决定甲烷选择性。

  14. Commercial Application of the PS-Ⅵ Catalyst in the Revamped 0.8 Mt/a Catalytic Reforming Unit

    Institute of Scientific and Technical Information of China (English)

    Leng Jiachang; Hou Zhanggui

    2006-01-01

    This article makes an analysis on the major technical difficulties encountered in the process of revamping and expanding the capacity of the continuous catalytic reforming (CCR) unit from 600 kt/a to 800kt/a at Tianjin Petrochemical Company. The requirements for expanding the CCR unit capacity to 800 kt/a have been met through adopting the low carbon-make PS-Ⅵ catalyst, properly lowering the RONC of the reformate, and appropriately retrofitting the towers and furnaces while keeping the reaction system, the catalyst regeneration system and the recycle hydrogen compressor intact. The calibration results have revealed that the liquid yield of reformate products, the octane rating of reformate, the pure hydrogen yield,the aromatics yield and the overall conversion rate all have met the revamp design targets.

  15. Preliminary Study on the Vaporization Ratio of the Slurry in the Residue Fluid Catalytic Cracking Disengager%RFCC沉降器内油浆气化率的初步研究

    Institute of Scientific and Technical Information of China (English)

    闫平祥; 蓝兴英; 徐春明; 高金森

    2007-01-01

    The vaporization ratios of the slurry at various temperature and partial pressure were calculated with the group-contribution method, and then the phase state of the slurry in the residue fluid catalytic cracking (RFCC) disengager was determined.This research could provide some advices on how to select the technological conditions to decrease the coking in the RFCC disengager.The oil gas temperature and the slurry partial pressure had significant effects on the vaporization ratio of the slurry.Increasing the oil gas temperature and reducing the slurry partial pressure could effectively slow down the coking speed in the RFCC disengager.According to the calculation results, a correlation was established to predict the vaporization ratio of the slurry under different operating conditions.

  16. Demographic and socioeconomic correlates of powder cocaine and crack use among high school seniors in the United States

    Science.gov (United States)

    Palamar, Joseph J.; Ompad, Danielle C.

    2016-01-01

    Objectives Rates of powder cocaine and crack use have fluctuated among adolescents over recent decades. Little attention has been paid to recent trends, particularly regarding differences between users of powder cocaine and crack—two forms of the substance that are commonly reported together as “cocaine” use, despite having different effects and rates of adverse outcomes. Methods We examined data from nationally representative samples of high school seniors who participated in the Monitoring the Future study during years 2005–2011 (weighted N=65 717). Results Many demographic and socioeconomic variables were similarly correlated with lifetime use of powder cocaine and crack. Income of >$50/week from job increased the odds for use, and income of >$50/week from sources other than a job more than doubled the odds for use. High religiosity, high parent education, identifying as black, and residing with one or two parents reduced odds for use. Hispanic students were at higher odds for use of crack and females were at lower odds for using powder cocaine. Among cocaine users, residing with one or two parents lowered odds for using both forms, and more religious students and Hispanics were at higher odds for crack-only use. Conclusions Those interested in preventing initiation and adverse consequences of cocaine use should take into account the overlapping, yet different risk profiles of powder cocaine and crack users when developing programming. This is particularly important when considering differences in legal consequences for these pharmacologically similar forms of cocaine. PMID:24191647

  17. Investigation of a catalytic gas generator for the Space Shuttle APU. [hydrazine Auxiliary Propulsion Unit

    Science.gov (United States)

    Emmons, D. L.; Huxtable, D. D.; Blevins, D. R.

    1974-01-01

    An investigation was conducted to establish the capability of a monopropellant hydrazine catalytic gas generator to meet the requirements specified for the Space Shuttle APU. Detailed analytical and experimental studies were conducted on potential problem areas including long-term nitriding effects on materials, design variables affecting catalyst life, vehicle vibration effects, and catalyst oxidation/contamination. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The objective of the first test series was to demonstrate the capability of the gas generator to successfully complete 20 simulated Space Shuttle missions in steady-state operation. The gas generator was then refurbished and subjected to a second series of tests to demonstrate the pulse-mode capability of the gas generator during 20 simulated missions. The third series of tests was conducted with a refurbished reactor to further demonstrate pulse-mode capability with a modified catalyst bed.

  18. Multifaceted effects of HZSM-5 (Proton-exchanged Zeolite Socony Mobil-5) on catalytic cracking of pinewood pyrolysis vapor in a two-stage fixed bed reactor.

    Science.gov (United States)

    Wang, Yimeng; Wang, Jie

    2016-08-01

    The pinewood was pyrolyzed in the first reactor at a heating rate of 10°Cmin(-1) from room temperature to 700°C, and the vapor was allowed to be cracked through the second reactor in a temperature range of 450-750°C without and with HZSM-5. Attempts were made to determine a wide spectrum of gaseous and liquid products, as well as the mass and element partitions to gas, water, bio-oil, coke and char. HZSM-5 showed a preferential deoxygenation effect via the facilitated decarbonylation and decarboxylation with the inhibited dehydration at 550-600°C. This catalyst also displayed a high selectivity for the formations of aromatic hydrocarbons and olefins by the promoted hydrogen transfer to these products at 550-600°C. The bio-oil produced with HZSM-5 at 500-600°C had the yields of 14.5-16.8%, the high heat values of 39.1-42.4MJkg(-1), and the energy recoveries of 33-35% (all dry biomass basis). PMID:27209452

  19. 催化裂化油浆中硫化物气相色谱分析%Determination of Sulfur Compounds in Catalytic Cracking Slurry by Gas Chromatography With Sulfur Chemiluminescence Detection

    Institute of Scientific and Technical Information of China (English)

    何俊辉; 贾广信; 黎爱群; 薛晓军

    2014-01-01

    采用气相色谱配硫化学发光检测器(SCD)结合高温模拟蒸馏ASTM D7169-05方法对巴陵石化催化裂化油浆中含硫化合物进行了分析鉴定,结果表明:油浆的馏程在253℃到690℃左右范围内,硫化物类型主要是二苯并噻吩类和萘并噻吩类化合物;定量分析结果表明,萘并噻吩类化合物占油浆中总硫化物含量的70%以上。%The catalytic cracking slurry was analyzed by gas chromatography with sulfur chemiluminescence detection (GC-SCD) and SimDis ASTM D7169-05 method. The results show that distillation range of the slurry is from 253 ℃to 690 ℃,and main sulfide types are dibenzothiophenes and naphthothiophenes. Quantitative analysis results show that naphthothiophene compounds account for more than 70%of the total sulfur content in the slurry.

  20. Entirely automatic on-line analysis system applied to catalytic cracking of gasoline%汽油催化裂化的全自动在线分析系统

    Institute of Scientific and Technical Information of China (English)

    薛青松; 王一萌

    2011-01-01

    With one set of idle catalyst-testing equipment and three gas chromatograph, a novel system for entirely automatic on-line analyzing gasoline catalytic cracking products was developed by re-equipping the only automatic pneumatic controller adapted for directing three way of six-channel valves simultaneously. The modified equipment results of synchronism, multitasking and high robotization of reaction-analysis system, more time and resources were saved, either. Furthermore, the six-channel valves on standby status were revised adapted for clearer analysis system.%利用实验室闲置的高压微反应装置和气相色谱仪,通过改装高压微反应装置上唯一一路自动气动控制系统,使其同时控制三路六通阀,实现高压微反应-三台色谱-三套色谱软件联动,全自动在线分析汽油催化裂解产物,不仅实现了反应-分析的同步性、多任务化和高度自动化,实验成本也大幅下降.并对六通阀原待采样模式进行了改进,大幅降低了对管道的污染.

  1. THE VALENCE STATE OF VANADIUM AND ITS POISONOUS EFFECT ON CATALYSTS DURING CATALYTIC CRACKING PROCESS%钒在催化裂化过程中的价态及其对催化剂的毒害

    Institute of Scientific and Technical Information of China (English)

    谭丽; 汪燮卿; 朱玉霞; 王子军

    2013-01-01

    A review concerning the valence state of vanadium on catalysts during catalytic cracking process, factors affecting the variation of vanadium valence states, poisoning effect on catalysts caused by various vanadium oxides and mechanism of poisoning, as well as research methods, characterization tools and essential results, is presented.It can be concluded that the negative effect on the structure and performance of FCC catalysts by high valence state of vanadium species is much more serious than that of by low valence state vanadium species.%综述催化裂化过程中钒的价态、影响钒价态变化的因素、不同价态钒对催化剂的毒害及其原因,以及相关研究方法、表征手段和主要研究结果.从对催化剂结构和性能两方面的影响看,高价态钒对催化裂化的负面影响远远超过低价态钒.

  2. Construction, evaluation and demonstration of mobile catalytic combustion units for destruction of methane and different odor pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Jannasch, Anna-Karin [Catator AB, Lund (Sweden)

    2012-02-15

    This project reports on the construction, the evaluation and the demonstration of novel, mobile small-scale (< 100 Nm{sup 3}/h) combustion units for reduction of methane and/or different odour pollutants (e.g. hydrogen sulfide, ammonia, VOC) existing in small concentrations in process air streams. The evaluated units include a regenerative (MeshRegenOx/MRO) and a recuperative, catalytic unit (Deodoron), respectively, which both are based on Catator's proprietary wire mesh catalyst technology. The evaluation and the demonstration work have involved laboratory tests with synthetic gases and a number of field tests at plants for biogas production, water and waste treatment. The results show that: 1. In comparison to conventional thermal emission abatement systems, the wire mesh catalyst technology opens up for the construction of very compact (V=0.6 Nm, W=500 kg for 1000 Nm{sup 3}/h) and thermo-economical systems (> 95 %), which technology can easily be scaled up and integrated into existing industrial and/or process streams. 2. Catator's MRO-prototype enables for autothermal oxidation of methane, with a conversion degree of 97-98 %, from an inlet concentration of 0.2 vol% at an operation temperature of 660-700 deg, i.e. 200-300 deg less than when conventional homogenous flame combustion is applied. 3. The performance of the MRO-unit was seen to be somewhat unstable, with an oscillating conversion degree during the operation cycle. This should however be able to overcome by further optimizing the integrated catalyst package and the heat exchanger. Significant improvements in efficiency and stability are also to be expected by the scale-up due to a decreasing heat loss with an increasing capacity 4. Close to 100 % removal of different odorants, with a thermal efficiency of around 80 %, can be obtained by the use of Catator's unit Deodoron at an operation temperature of 300-400 deg. The results were verified by odor tests performed up- and downstream the

  3. RESEARCH ON CONVERSION RULES OF POLYCYCLIC AROMATICS IN CATALYTIC CRACKING%多环芳烴在催化裂化过程中的转化规律研究

    Institute of Scientific and Technical Information of China (English)

    刘银亮

    2016-01-01

    在中型催化裂化装置上,采用 MLC-500催化剂,以劣质直馏蜡油为原料,通过考察不同转化率条件下重芳烃在催化裂化重质馏分油(简称重油)中的传递系数,得到各类芳烃在催化裂化反应中的转化规律。结果表明:当多环芳烃转化率低于48.22%时,主要发生多环芳烃侧链断裂反应;转化率为48.22%~62.71%时,三环、四环芳烃在催化裂化重油中的传递系数变化不大,芳核较为稳定,总多环芳烃在重油中的传递系数为0.3~0.4,此转化率区间为高选择性催化裂化合理区间;转化率高于62.71%时,多环芳烃缩合反应加剧,对生焦贡献率增加。%The transfer coefficient and conversion rules of polycyclic aromatic hydrocarbons of heavy oil at different conversion rates were obtained with a FCC pilot plant and MLC-500 catalyst. The test re-sults illustrate that when the conversion rate is below 48.22%,the main reaction of polycyclic aromatic hydrocarbons is the cracking of branched chain;when the conversion rates are in the range of 48.22% to 62.71%,the total transfer coefficients of the three and four ring aromatics in the heavy oil is about 0.3—0.4,the rage is suitable for both the stability of aromatic nucleus and the high selectivity for cata-lytic cracking. The polycyclic aromatic hydrocarbons condensate rapidly if the conversion rate is higher than 62.71%,resulting in coke formation.

  4. La conversion des résidus et huiles lourdes : au carrefour du thermique et du catalytique Conversion of Residues and Heavy Oils At the Crossroads of Thermal Cracking and Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Le Page J. F.

    2006-11-01

    Full Text Available Cet article passe en revue les diverses familles de procédés de conversion des résidus et huiles lourdes. Tous les résultats semblent converger pour accréditer l'idée que dans tous ces procédés, y compris les procédés dits catalytiques, l'essentiel de la conversion des espèces de poids moléculaire élevé, résines et asphaltènes, procède par mécanisme radicalaire : la clef de la conversion profonde, c'est paradoxalement la maîtrise de la condensation radicalaire de ces espèces. Hydrogène seul, hydrogène en présence de solvant donneur, d'additifs ou encore mieux de catalyseurs, sont les armes dont dispose tout raffineur pour affirmer cette maîtrise, dans la mesure où il ne tient pas à fabriquer du coke. Tous ces procédés de conversion des résidus donnent par ailleurs naissance à des produits craqués dont la nature et la distribution rappellent celles des produits de première distillation du pétrole brut dont est issu le résidu soumis au craquage. This article reviews the different families of conversion processes for residues and heavy oils. All the results seem to converge to support the idea that in all these processes, including so-called catalytic processes, most of the conversion of high-molecular-weight species (resins and asphaltenes operates by a radical mechanism. The key to in-depth conversion is, paradoxically, the mastery of the radical condensation of these species. Hydrogen alone, hydrogen in the presence of a donor solvent, of additives or, better yet, of catalysts, are the arms at the disposal of all refiners to assert this mastery, to the extent that they do not want to manufacture coke. All such conversion processes for residues also give rise to cracked products whose nature and distribution recall those of first-distillation products of crude oil, from which the residue comes that is subjected to cracking.

  5. Synthesis, characterizations and catalytic studies of a new two-dimensional metal−organic framework based on Co–carboxylate secondary building units

    Energy Technology Data Exchange (ETDEWEB)

    Bagherzadeh, Mojtaba, E-mail: bagherzadeh@sharif.edu [Department of Chemistry, Sharif University of Technology, PO Box 11155-3516, Tehran (Iran, Islamic Republic of); Ashouri, Fatemeh [Department of Chemistry, Sharif University of Technology, PO Box 11155-3516, Tehran (Iran, Islamic Republic of); Đaković, Marijana [Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb (Croatia)

    2015-03-15

    A metal–organic framework [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P2{sub 1}/n space group with a=13.989(3) Å, b=9.6728(17) Å, c=16.707(3) Å, and Z=2. The polymer features a framework based on the perfect octahedral Co–O6 secondary building units. The catalytic activities of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant degradation in catalytic activity. Furthermore, no contribution from homogeneous catalysis of active species leaching into reaction solution was detected. - Graphical abstract: A metal–organic framework of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] was synthesized by hydrothermal method. This 2D-periodic framework is constructed from the infinite Co–O–C secondary building units and crystallizes in the monoclinic P2{sub 1}/n space group based on Co(II)–carboxylate units. The catalytic oxidation of various olefins was effectively carried out with [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} catalyst by TBHP as oxidant. - Highlights: • A metal–organic framework of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] is prepared by hydrothermal method. • The [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} is constructed from Co–carboxylate secondary building units. • This coordination polymer displayed high catalytic activity for olefin oxidation reactions. • The catalytic reaction is heterogeneous and catalyst can be simply separated. • The heterogeneous catalyst can be reused several times without significant loss of catalytic activity.

  6. Effects of post treatment of HZSM-5 zeolites on catalytic cracking of butene%后处理改性对HZSM-5沸石丁烯裂解性能的影响

    Institute of Scientific and Technical Information of China (English)

    张荣荣; 王正宝

    2015-01-01

    The structure and acidity of HZSM-5 zeolites were modified using different post treatment methods: alkaline treatment, steam treatment, and alkaline-steaming treatment. The catalytic performances of modified zeolites were tested in 1-butene catalytic cracking. Their physicochemical properties were characterized by N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy with pyridine adsorption (Py-IR). The acidities of zeolites increased after the alkaline treatment, and as a result, the activity of butene cracking increased and the selectivity of propylene decreased. However, the deactivation rate of alkaline-treated zeolites had no significant change. There was a pronounced development of mesopores (5—20 nm) with a broad pore-size distribution in alkaline-treated ZSM-5 zeolites. Mesopores (2—4 nm) with a narrow distribution is observed after steaming treatment, while the mesopore volume is low. Zeolites after alkaline- and steaming-treatment showed two kinds of mesopore distributions, 2—4 nm (narrow) and 5—20 nm (broad). Due to the decrease of Brønsted acidic sites, the selectivity of propylene increased over ZSM-5 zeolites with any of the post treatments; a relatively stable propylene yield was obtained after the reaction of 2.5 h (except for zeolites treated with high concentration of alkaline followed by steaming treatment).%采用不同后处理手段(碱处理、水汽处理以及碱处理-水汽处理)对HZSM-5沸石的孔结构和酸性质进行了调变,并对其丁烯裂解性能进行了研究。运用N2吸脱附、扫描电镜(SEM)、X射线衍射(XRD)以及吡啶吸附红外(Py-IR)对后处理改性前后的沸石样品的物理化学性质进行了表征。碱处理后HZSM-5的质子酸量增加,在5~20 nm处具有分布较宽的介孔,其反应活性升高,丙烯选择性下降,但失活速率没有加快。单独水汽处理在2~4 nm处产生介孔,但介孔体

  7. Process Simulation and Optimization for Absorption and Stabilization System of Fluid Catalytic Cracking%催化裂化吸收稳定系统流程模拟与优化

    Institute of Scientific and Technical Information of China (English)

    代广超; 程明

    2012-01-01

    针对目前催化裂化吸收稳定系统普遍存在干气中液化气组分含量高的问题,利用HYSYS模拟软件对某石化企业的催化裂化装置吸收稳定系统进行了模拟.对影响干气中C3组分含量的补充吸收剂量、吸收塔顶温度和解吸塔进料温度进行了模拟和分析,并提出合理参数配置.结果表明,补充吸收剂流量为40 t/h,吸收塔塔顶温度35℃,解吸塔进料温度50℃时,吸收效果大为改善,其中干气中C3组分含量较优化前降低了0.92%.%In view of high content of C3 and C4 components in dry gas, absorption and stabilization system of fluid catalytic cracking(FCC) in a refinery was stimulated using HYSYS simulation software. The parameters influencing content of C3 such as flow of supplementary absorption agent, temperature at the top of adsorption column, and temperature of feed in desorption column were stimulated and analyzed. Reasonable allocation of these parameters was given. The results showed that the adsorption efficiency was greatly improved with the content of C3 component in dry gas decreased by 0.92% compared with that before optimization when flow of supplementary absorbent was 40 t/h, temperatures at the top of absorption column and at the inlet of desorption column were 35 and 50 ℃, respectively.

  8. Determination of micro content carbon element in catalytic cracking catalyst by coulometry%库仑法测定催化裂化催化剂中的微量碳

    Institute of Scientific and Technical Information of China (English)

    赵军; 张瑛; 陈亮; 马素娥; 乔涛

    2009-01-01

    An analytical method was developed for determination of micro content carbon in catalytic cracking catalyst by using automatic carbon and hydrogen element analyzer. The sample was conbusted in a high-temperature furnace, and the carbon element was changed into carbon dioxide, which was reacted with LiOH to produce water. The water produced was sent into an electrolytic cell. According to Faraday's law, the carbon content in the sample can be calculated with the quantity of electricity consumed in the electrolysis process. The method has the advantages of good repeatability, good precision, high accuracy, and low detection limit. It can be effectively used for catalyst analysis in production.%采用库仑法全自动碳氢元素分析仪,建立了一种催化裂化催化剂中微量碳含量的分析方法.样品经高温燃烧,碳生成二氧化碳,二氧化碳再与氢氧化锂反应生成相应的水,将水送入涂有五氧化二磷的电解池电解,测量电解所消耗的电量,依照法拉第电解定律计算出样品中的碳含量.实验证明,该分析方法重复性好,准确度高,检测限低,能够满足催化装置上的催化剂分析需要,对实际生产具有指导意义.

  9. Cracking the Credit Hour

    Science.gov (United States)

    Laitinen, Amy

    2012-01-01

    The basic currency of higher education--the credit hour--represents the root of many problems plaguing America's higher education system: the practice of measuring time rather than learning. "Cracking the Credit Hour" traces the history of this time-based unit, from the days of Andrew Carnegie to recent federal efforts to define a credit hour. If…

  10. On-line catalytic cracking of vapors from cellulose fast pyrolysis%纤维素快速热解反应气体的在线催化裂解

    Institute of Scientific and Technical Information of China (English)

    李攀; 李缔; 隋海清; 邵敬爱; 王贤华; 陈汉平

    2015-01-01

    The MHZSM-5(M=Fe, Zr and Co) zeolite catalysts prepared by impregnation method were characterized using laser particle size analyzer, specific surface area and pore size analyzer and X-ray diffraction (XRD), and applied for on-line cracking vapors from cellulose fast pyrolysis with vertical two-stages furnace. The bio-oils obtained by direct liquefaction with and without catalysts were characterized by GC-MS analyses. The results indicated that with introduction of catalysts, liquid yield decreased from 52.06% to 23.63%, while gas yield increased up to 70.84% from 42.39%; and CoHZSM-5 showed the most obvious effect for catalytic pyrolysis. The component of bio-oil from fast pyrolysis of cellulose was mainly 1,6-dehydration-β-D-glucopyranose (levoglucosan). After the addition of catalysts to online catalytically reform vapors of cellulose fast pyrolysis, the contents of aromatics increased significantly in the product, and FeHZSM-5 and ZrHZSM-5 had the best effect. The content of levoglucosan was increased to 63.78% for HZSM-5 catalyst. The contents of acetic acid and propionic acid were reduced slightly by catalytic pyrolysis. Based on the balance of the yield and composition of bio-oil, it was considered that FeHZSM-5 and ZrHZSM-5 played more significant role during cellulose fast pyrolysis.%通过浸渍法制备 MHZSM-5(M=Fe,Zr,Co)催化剂,采用激光粒度分析仪、比表面积及孔径分析仪和 X射线衍射仪(XRD)对催化剂的性质进行表征,并在立式两段加热炉上进行纤维素快速热解蒸汽的在线催化实验。对不同催化剂条件下的产物分布特性及生物油组成特性进行分析,结果表明,随着催化剂的引入,液相产率从52.06%最大下降至23.63%,气相产率从42.39%最大提高至70.84%,CoHZSM-5对于热解蒸汽的催化气化效果最为明显;纤维素快速热解生物油中以1,6-脱水-β-D-吡喃葡萄糖(左旋葡聚糖)为主,引入催化剂对纤维素热解蒸

  11. Catalytic pyrolysis of oilsand bitumen over nanoporous catalysts.

    Science.gov (United States)

    Lee, See-Hoon; Heo, Hyeon Su; Jeong, Kwang-Eun; Yim, Jin-Heong; Jeon, Jong-Ki; Jung, Kyeong Youl; Ko, Young Soo; Kim, Seung-Soo; Park, Young-Kwon

    2011-01-01

    The catalytic cracking of oilsand bitumen was performed over nanoporous materials at atmospheric conditions. The yield of gas increased with application of nanoporous catalysts, with the catalytic conversion to gas highest for Meso-MFI. The cracking activity seemed to correlate with pore size rather than weak acidity or surface area. PMID:21446540

  12. Catalytic Cracking of Heptane Using Prepared Zeolite

    OpenAIRE

    Mohammed Nsaif; Ahmed Abdulhaq; Ali Farhan; Safa Neamat

    2012-01-01

    This investigation was conducted to study the potential of type Y-zeolite prepared locally from Iraqi Rice Husk (IRH) (which considered as a type of agricultural waste that difficult to discard it in conventional methods in Iraq) on the removal of one heavy metals pollutant which was divalent zinc (Zn+2) ions from industrial wastewater using different design parameters by adsorption process. The design parameters studied to remove (Zn+2) ions using zeolite prepared locally from (IRH) as an ad...

  13. Copper containing hydrocarbon cracking catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lussier, R.J.; Magee, J.S. Jr.

    1975-12-30

    A copper-exchanged zeolite cracking catalyst capable of producing high octane gasoline of increased aromatic and olefinic content is described. Mixtures of copper and hydrogen ions are exchanged into a Y-type zeolite using a combination of exchange and calcination steps. The exchanged zeolite is advantageously combined with a major portion of inorganic oxide matrix to produce a catalyst suitable for use in standard commercial fluid and moving bed cat-cracking units. (auth)

  14. 40 CFR Table 7 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Metal HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... Method 6010B, Inductively Coupled Plasma-Atomic Emission Spectrometry, EPA Method 6020, Inductively Coupled Plasma-Mass Spectrometry, EPA Method 7520, Nickel Atomic Absorption, Direct Aspiration, or EPA Method 7521, Nickel Atomic Absorption, Direct Aspiration; or by an alternative to EPA Method 6010B,...

  15. 40 CFR Table 4 to Subpart Uuu of... - Requirements for Performance Tests for Metal HAP Emissions From Catalytic Cracking Units Not...

    Science.gov (United States)

    2010-07-01

    ... Plasma-Atomic Emission Spectrometry, EPA Method 6020, Inductively Coupled Plasma-Mass Spectrometry, EPA Method 7520, Nickel Atomic Absorption, Direct Aspiration, and EPA Method 7521, Nickel Atomic Absorption.... Measure PM emissions. Method 5B or 5F (40 CFR part 60, appendix A) to determine PM emissions...

  16. Synthesis and characterization of type silicoaluminophosphates catalytic support

    International Nuclear Information System (INIS)

    The refining processes, the catalytic hydrocracking is the future of diesel oil in Brazil and the first units are already scheduled to be inaugurated. Among the catalysts used in this process, silicoaluminophosphates (SAPO's) have considerable potential for use as they have been effective in the isomerization of n-alkanes, the isomerization of olefins and alkylation of aromatics. Because of this, the objective is to develop catalysts that will be used in hydrocracking reactions. The media like SAPO-5 were synthesized with different ratios silicon/aluminum, which is used as a catalytic support and have the function of crack organic molecules, since it has acidic character. The materials were characterized by techniques: X-ray diffraction, chemical analysis and textural by BET. After summarizing the media found that they had agreements with the crystalline phases presented in the literature.(author)

  17. The underclad cracking in PWR reactor vessels

    International Nuclear Information System (INIS)

    The article describes the kind of cracking which can occur under the stainless steel cladding during the manufacturing process of PWR vessels: - cold cracking recently found in France on vessel nozzles-reheat cracking discovered some ten years ago in particular in Germany and in USA. Methods of examination for underclad cracking are put forward, together with results obtained on vessel nozzles of units currently being built in Belgium. Some nozzles are affected by the phenomenon of reheat cracking, whilst the hypothesis of cold cracking, which had been proposed because of the similar situation found in France should probably be abandoned. On the basis of the investigations and studies made, it is established that the cracking involved does not jeopardize the integrity of the vessels during their life time. (author)

  18. Craqueamento catalítico de polietileno em condições de refinaria: produção de frações combustíveis Catalytic cracking of polyethylene under refinery conditions: production of combustible fractions

    Directory of Open Access Journals (Sweden)

    Alessandra M. Ribeiro

    2006-12-01

    Full Text Available Este trabalho foi realizado em uma unidade de teste de microatividade para estudar o processo de craqueamento catalítico das cargas combinadas de polietileno de baixa densidade e polietileno de alta densidade com vaselina, frente a catalisadores comerciais de FCC (alta e baixa atividades, para avaliar a produção das frações combustíveis (gasolina, diesel e resíduo. As cargas combinadas de PEBD e PEAD/vaselina foram processadas em condições de refinaria. Para as cargas de PEBD/vaselina, a 2, 6 e 10% p/p, a produção da fração gasolina foi favorecida pelo catalisador de alta atividade, enquanto que a carga de PEAD/vaselina a 2% p/p, para produção da mesma fração, o catalisador de baixa atividade apresentou melhor eficiência. Todas as cargas combinadas, nas diversas concentrações, mostraram que o material inerte (caulim apresenta maior atuação, na produção da fração resíduo, indicando a ocorrência preferencial de craqueamento térmico.This work was carried out in an unit of microactivity test, to study the process of combined feeds of low density and high density polyethylenes with vaseline and commercial FCC catalysts (of low and of high activities, to evaluate the production of fuel fractions (gasoline, diesel and residue. The combined feeds of PEBD and PEAD/vaseline, at different concentrations, were processed under refinery conditions. For feeds of PEBD/vaseline at 2, 6 and 10% w/w, production of the gasoline fraction was favored with the high-activity catalyst, while for the PEAD/vaseline feed at 2%, in the production of the same fraction, the low-activity catalyst presented better performance. For all the combined feeds, in all concentrations, the inert material showed better performance for the production of residue fraction, indicating the preferential occurrence of thermal cracking.

  19. Converter塔底油裂化助剂在催化裂化装置上的应用%Application of Converter additive for bottom oil cracking in fluidized- bed catalytic cracking unit

    Institute of Scientific and Technical Information of China (English)

    沈赟

    2009-01-01

    在催化裂化装置中加入能够增加重油裂化能力、提高平衡催化剂活性的Converter塔底油裂化助剂(简称Convener助剂).工业应用表明,使用Converter助剂后,在原料性质变差的情况下,干气质量分数下降0.10个百分点,焦炭质量分数没有变化,油浆质量分数下降1.08个百分点,总液收率提高1.08个百分点;汽油研究法辛烷值保持在92左右,烯烃体积分数不大于35%;催化剂单耗下降0.011 kg/t.

  20. Computational investigation of hydrodynamics and cracking reaction in a heavy oil riser reactor

    Institute of Scientific and Technical Information of China (English)

    Jian Chang; Kai Zhang; Fandong Meng; Longyan Wang; Xiaoli Wei

    2012-01-01

    This paper presents a computational investigation of hydrodynamics,heat transfer and cracking reaction in a heavy oil riser operated in a novel operating mode of low temperature contact and high catalyst-to-oil ratio.Through incorporating feedstock vaporization and a 12-lump cracking kinetics model,a validated gas-solid flow model has been extended to the analysis of the hydrodynamic and reaction behavior in an industrial riser.The results indicate that the hydrodynamics,temperature and species concentration exhibit significantly nonuniform behavior inside the riser,especially in the atomization nozzle region.The lump concentration profiles along the riser height provide useful information for riser optimization.Compared to conventional fluid catalytic cracking (FCC) process,feedstock conversion and gasoline yield are respectively increased by 1.9 units and 1.0 unit in the new FCC process,the yield of liquefied petroleum gas is increased by about 1.0 unit while dry gas yield is reduced by about 0.3 unit.

  1. Mesoporous zeolite single crystals for catalytic hydrocarbon conversion

    DEFF Research Database (Denmark)

    Schmidt, I.; Christensen, C.H.; Hasselriis, Peter;

    2005-01-01

    Recently, mesoporous zeolite single crystals were discovered. They constitute a novel family of materials that features a combined micropore and mesopore architecture within each individual crystal. Here, we briefly summarize recent catalytic results from cracking and isomerization of alkalies, a...

  2. Catalytic Fast Pyrolysis: A Review

    Directory of Open Access Journals (Sweden)

    Theodore Dickerson

    2013-01-01

    Full Text Available Catalytic pyrolysis is a promising thermochemical conversion route for lignocellulosic biomass that produces chemicals and fuels compatible with current, petrochemical infrastructure. Catalytic modifications to pyrolysis bio-oils are geared towards the elimination and substitution of oxygen and oxygen-containing functionalities in addition to increasing the hydrogen to carbon ratio of the final products. Recent progress has focused on both hydrodeoxygenation and hydrogenation of bio-oil using a variety of metal catalysts and the production of aromatics from bio-oil using cracking zeolites. Research is currently focused on developing multi-functional catalysts used in situ that benefit from the advantages of both hydrodeoxygenation and zeolite cracking. Development of robust, highly selective catalysts will help achieve the goal of producing drop-in fuels and petrochemical commodities from wood and other lignocellulosic biomass streams. The current paper will examine these developments by means of a review of existing literature.

  3. Study of gas-solid contact in an ultra-rapid reactor for cumene catalytic cracking; Etude du contact gaz-solide dans un reacteur a co-courant descendant par la mise en oeuvre du craquage catalytique du cumene

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, J.

    1996-11-05

    Few studies have been carried out on the notion of gas-solid contact in ultra-rapid reactors. Both gas and solid move in the reactor and the contact can be directly estimated when using a chemical reaction such as cumene cracking. It`s a pure and light feedstock whose kinetics can be determined in a fixed bed. The study was carried out on a downflow ultra-rapid reactor (ID = 20 mm, length = 1 m) at the University of Western Ontario. It proved that the quench and the ultra-rapid separation of gas and solid must be carefully designed in the pilot plant. Cumene conversion dropped when reducing gas-solid contact, which led to push the temperature over 550 deg. C and increase the cat/oil ratio at 25 working at solid mass fluxes below 85 kg/m{sup 2}.s. Change of selectivity at very short residence time were also observed due to deactivation effects. Experiments made by Roques (1994) with phosphorescent pigments on the Residence Time Distribution of solids gave Hydrodynamic data on a cold flow copy of the pilot plant. Experiments made on packed bed gave kinetic data on the cracking of cumene. These data were combined to optimize a mono dimensional plug flow model for cumene cracking. (author)

  4. Preliminary Study on Reducing Olefin Content of FCC Gasoline over Cracking Catalyst

    Institute of Scientific and Technical Information of China (English)

    梁咏梅; 杨海峰; 刘耀芳; 徐春明

    2003-01-01

    Using fixed bed micro-reactor and cracking catalyst, re-cracking of fluid catalytic cracking (FCC) gasoline at lower temperature than conventional cracking condition has been studied. The results reveal that at lower temperature from 350℃-450℃ and catalyst to feed ratio of 3, the olefin content is reduced from 49% to 27%(by mass) over the catalyst whose micro-reacting activation index is 53, and the octane number is kept on high level.

  5. Stress corrosion cracking experience in steam generators at Bruce NGS

    International Nuclear Information System (INIS)

    In late 1990 and through 1991, units 1 and 2 at the Bruce A Nuclear Generating Station (BNGS-A) experienced a number of steam generator tube leaks. Tube failures were identified by eddy current to be circumferential cracks at U-bend supports on the hot-leg side of the boilers. In late 1991, tubes were removed from these units for failure characterization. Two active failure modes were found: corrosion fatigue in both units 1 and 2 and stress corrosion cracking (SCC) in unit 2. In unit 2, lead was found in deposits, on tubes, and in cracks, and the cracking was mixed-mode: transgranular and intergranular. This convincingly indicated the involvement of lead in the stress corrosion cracking failures. A program of inspection and tube removals was carried out to investigate more fully the extent of the problem. This program found significant cracking only in lead-affected boilers in unit 2, and also revealed a limited extent of non-lead-related intergranular stress corrosion cracking in other boilers and units. Various aspects of the failures and tube examinations are presented in this paper. Included is discussion of the cracking morphology, measured crack size distributions, and chemical analysis of tube surfaces, crack faces, and deposits -- with particular emphasis on lead

  6. 智能在线监测系统在催化装置的应用%APPLICATION OF INTELLIGENT ONLINE MONITORING SYSTEM ON CATALYTIC UNIT

    Institute of Scientific and Technical Information of China (English)

    赵伟; 周亮

    2015-01-01

    Work principle and main structure part of the intelligent online monitoring sys-tem were introduced.Actual application of the system on the catalytic unit in some refinery showed that vibration and temperature of the pumps could be gathered timely and accurately by the system, alarm indication and overhaul could be given basing on abnormal state of the data , purpose of execution of overhaul in accordance of the situation was achieved , and the effect of the monitoring system was obvious .%介绍智能在线监测系统的工作原理以及其主要结构组成,通过在某炼厂催化装置的实际应用,说明该系统能够及时、准确的采集到机泵设备的振动和温度数据,并且根据数据的异常状况给出报警提示和检修建议,达到了依据状态进行检修的效果,监控效果显著。

  7. Modified Dugdale cracks and Fictitious cracks

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1998-01-01

    A number of theories are presented in the literature on crack mechanics by which the strength of damaged materials can be predicted. Among these are theories based on the well-known Dugdale model of a crack prevented from spreading by self-created constant cohesive flow stressed acting in local...... areas, so-called fictitious cracks, in front of the crack.The Modified Dugdale theory presented in this paper is also based on the concept of Dugdale cracks. Any cohesive stress distribution, however, can be considered in front of the crack. Formally the strength of a material weakened by a modified.......For brittle materials (considered by the Griffith theory )G_CR = 2 Gamma where Gamma is surface energy of material considered. For more tough materials (considered by the modified Dugdale theory) G_CR is a function f(sigma_L delta_CR) where sigma_L and delta_CR are theoretical strength and flow limit...

  8. A stress corrosion cracking experience

    Energy Technology Data Exchange (ETDEWEB)

    Dicic, Z.

    1999-07-01

    Severe cracking was found on two discs when a steam turbine was inspected during the outage to replace the last stage blades (LSB). The cracks were on the inlet side in the form of star burst around balance holes, and in the form of long circumferential cracks in the region of the fillet radius between the disc and the shaft. In order to return the turbine to service, the turbine was modified by removing the disc that was damaged more severely, and by machining of the other to remove the cracks. The basis for the modifications was established after having performed metallurgical and deposit examination, and reviews of stress calculations and design features. Additional modifications were performed in order to improve the internal environment at location where the cracking had occurred. The turbine is a non-reheat, 3,600 RPM, single shaft, monoblock unit used in a combined cycle plant. The steam cycle is a two pressure system; The high pressure (HP) steam parameters are: 1,450 psig, and 950 F, and the low pressure (LP) induction steam: 60 psig, saturated. The first eight stages are action type. The induction steam inlet is followed by five reaction stages. There are no extractions. The source of steam is a two pressure, unfired Heat Recovery Steam Generator (HRSG). The boiler feed water is treated with phosphates.

  9. Fractional Catalytic Pyrolysis Technology for the Production of Upgraded Bio-oil using FCC Catalyst

    OpenAIRE

    Mante, Nii Ofei Daku

    2011-01-01

    Catalytic pyrolysis technology is one of the thermochemical platforms used to produce high quality bio-oil and chemicals from biomass feedstocks. In the catalytic pyrolysis process, the biomass is rapidly heated under inert atmosphere in the presence of an acid catalyst or zeolite to promote deoxygenation and cracking of the primary vapors into hydrocarbons and small oxygenates. This dissertation examines the utilization of conventional fluid catalytic cracking (FCC) catalyst in the fractiona...

  10. Research on a clean preparation process of sebacic acid by catalytic cracking of castor oil%蓖麻油催化裂解制备癸二酸的清洁工艺研究

    Institute of Scientific and Technical Information of China (English)

    王彦雄; 张小里; 李红亚; 豆坤坤; 张甜甜; 姚娜

    2012-01-01

    The traditional preparation process of sebacic acid by cracking castor oil could cause serious environment pollution because of using o-cresol as the diluent and lead oxide as the catalyst. Using liquid paraffin as the diluent, an environmental friendly catalyst for preparation of sebacic acid was screened and the clean preparation process of sebacic acid was investigated. The results showed that iron oxide as the catalyst exhibited good cracking effect;sebacic acid yield of 67.2% and the purity of 99.0% after separation were attained under the optimum condition as follows:catalyst dosage 1.00% of castor oil mass, V( diluent) : V( castor oil) =4-1, V( sodium hydroxide): V( castor oil) =1:1,reaction temperature 280?, and reaction time 4 h. Using iron oxide as the catalyst and liquid paraffin as the diluent,a clean preparation process of sebacic acid by cracking castor oil will be expected to be developed.%传统的蓖麻油裂解制备癸二酸工艺因使用稀释剂邻甲酚和催化剂铅氧化物而导致严重的环境污染.以对环境温和的液体石蜡作稀释剂,筛选环境友好型催化剂制备癸二酸,开发清洁生产工艺,研究发现,采用氧化铁作催化剂可取得良好的裂解反应效果.最佳工艺条件为:催化剂用量为蓖麻油质量的1.00%,V(稀释剂)∶V(蓖麻油)=4∶1,V(碱液)∶V(蓖麻油)=1∶1,反应温度280℃,反应时间4h.在此条件下,癸二酸收率达67.2%,分离后纯度达到99.0%.表明氧化铁作为催化剂配合液体石蜡作稀释剂可望开发一条蓖麻油裂解制备癸二酸的清洁生产工艺.

  11. Behavior of cracked materials

    CERN Document Server

    François, Marc Louis Maurice

    2009-01-01

    Due to their microstructure, quasi brittle materials present rough cracks. Under sliding of the crack lips, this roughness involves in one hand induced opening and in the other hand some apparent plasticity which is due to the interlocking of the crack lips combined with Coulomb's friction. The proposed model is written under the irreversible thermodynamics framework. Micromechanics uses the Del Piero and Owen's structured deformation theory. Opening of the crack depends upon the crack shape and the relative sliding of the crack lips. The thermodynamic force associated to the sliding has the mechanical meaning of the force acting in order to make the crack slide. Yield surface is defined as a limitation of this force with respect to the Coulomb's friction and the Barenblatt cohesion. The crack orientation is defined as the one for which the criterion is reached for the lowest stress level. A decreasing cohesion, respect to sliding is supposed. Tension and compression reference cases are envisaged.

  12. Tubing weld cracking test

    International Nuclear Information System (INIS)

    A tubing weld cracking (TWC) test was developed for applications involving advanced austenitic alloys (such as modified 800H and 310HCbN). Compared to the Finger hot cracking test, the TWC test shows an enhanced ability to evaluate the crack sensitivity of tubing materials. The TWC test can evaluate the cracking tendency of base as well as filter materials. Thus, it is a useful tool for tubing suppliers, filler metal producers and fabricators

  13. 硫磺回收装置余热锅炉过热器弯头开裂原因初步分析%Preliminary Analysis on Tube Cracking Cause of Waste Heat Boiler Superheater of the Sulfur Recovery Unit

    Institute of Scientific and Technical Information of China (English)

    李玉军; 蒋仕良

    2011-01-01

    Refinery sulfur recovery unit plays an important role in the entire production system, and the waste heat boiler superheater is the key component of the device. Because the condition is demanding and complex,the case of superheater elbow cracking was once reported. Through the comprehensive examina-tion and test on the macroscopic test about Elbow cracking parts, thickness measurement, spectrum anal-ysis , metallographic examination, hardness testing and chemical components analysis of stove ash fouling etc, the cause of cracking and the impact of the waste heat boiler superheater and its safe operation was analyzed, then the corresponding prevention and control measure is proposed.%炼化企业硫磺回收装置在整个生产系统中起着重要作用,而余热锅炉过热器是装置的关键组成部分,由于工况苛刻且较为复杂,曾有过热器弯头开裂案例报导,通过对弯头开裂部位宏观检查、测厚、光谱分析、金相检验、硬度测定及炉灰垢样化学成分分析等方面综合检验检测,分析了开裂的产生原因及其对余热锅炉过热器安全运行的影响,并提出了相应的预防与控制措施.

  14. 焦化蜡油中碱性氮化合物的ESI FT-ICR MS表征及其催化裂化反应特性%CHARACTERIZATION OF BASIC NITROGEN COMPOUNDS IN COKER GAS OIL BY ESI FT-ICR MS AND THEIR CATALYTIC CRACKING PERFORMANCE

    Institute of Scientific and Technical Information of China (English)

    陈小博; 沈本贤; 孙金鹏; 山红红

    2013-01-01

    利用盐酸-乙醇溶液对焦化蜡油(CGO)中的碱性氮化合物进行了萃取分离,采用电喷雾-傅里叶变换离子回旋共振质谱仪(ESI FT-ICR MS)对CGO及其盐酸抽提物中的碱性氮化合物进行了表征,并在小型提升管催化裂化实验装置上,考察了碱性氮化合物的催化裂化反应特性.结果表明:CGO中的碱性氮化合物以N1类化合物为主,主要是带烷基或环烷基侧链的喹啉类和苯并喹啉类衍生物;在催化裂化条件下,萃取出的碱性氮化合物仍具有一定的催化裂化性能,但转化率较低,主要发生烷基侧链、环烷基侧链以及联苯桥键的断裂反应,较高含量的碱性氮化合物和多环芳烃是导致其转化率低、产物分布差的关键因素.%The basic nitrogen compounds were extracted by hydrochloric acid and alcohol from CGO.Then the types and structures of basic nitrogen species in CGO and its hydrochloric extract were characterized by Electrospray Ionization (ESI) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS),and the catalytic cracking performance of the basic nitrogen compounds was studied.The data indicate that N1 type basic nitrogen compounds are dominant in CGO and these species are mainly derivatives of quinoline and benzoquinoline with alkyl and cycloalkyl chains.Under the conditions of FCC,the basic nitrogen compounds extracted from CGO still have certain catalytic cracking ability;however,the conversion is relatively low.The bond-breakages of alkyl side-chains,cycloalkyl side-chains and biphenyl bridge are the main reaction.High content of basic nitrogen compounds and polycyclic aromatic hydrocarbons are the key factors that lead to lower conversion and poorer products distribution.

  15. Study on the Role of Thermal Cracking in FCC Cycle

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Wei Xiaoli

    2004-01-01

    A bench-scale fixed fluidized bed reactor was used to study the distribution and quality of products derived from thermal cracking of VGO. Test results had shown that the space velocity has minor effect on thermal cracking reaction. The depth of thermal cracking reaction was mainly affected by the reaction temperature.At different reaction temperatures the form of free radicals thus initiated varied, resulting in different product distribution. At low temperature C10= and C11= olefins dominated in thermally cracked gasoline products,whereas at higher temperature C6=-C9= olefins dominated in thermally cracked gasoline products, among which C6 and C7 olefins were mainly composed of 2M 1 Cs= and 2E1C5=. Difference in olefin structure can lead to different reaction pathways of catalytic cycle.

  16. Kaolin and commercial fcc catalysts in the cracking of loads of polypropylene under refinary conditions

    Directory of Open Access Journals (Sweden)

    A. M. Ribeiro

    2013-12-01

    Full Text Available The efficiency of Commercial FCC catalysts (low, medium and high activities was evaluated by the catalytic cracking process of combined feeds of polypropylene (PP and vaseline, using a microactivity test unit (M.A.T. for the production of fuel fractions (gasoline, diesel and residue. The PP/vaseline loads, at 2.0% and 4.0% wt, were processed under refinery conditions (load/catalyst ratio and temperature of process. For the PP/vaseline load (4.0% wt, the production of the gasoline fraction was favored by all catalysts, while the diesel fraction was favored by PP/vaseline load (2.0% wt, showing a preferential contact of the zeolite external surface with the end of the polymer chains for the occurrence of the catalytic cracking. All the loads produced a bigger quantity of the gaseous products in the presence of highly active commercial FCC catalyst. The improvement in the activity of the commercial FCC catalyst decreased the production of the liquid fractions and increased the quantity of the solid fractions, independent of the concentration of the loads. These results can be related to the difficulty of the polymer chains to access the catalyst acid sites, occurring preferentially end-chain scission at the external surface of the catalyst.

  17. NO{sub x}-abatement in bio-fuelled combustion units through catalytic reburning; Minskning av NO{sub x}-emissioner fraan biobraensleeldade anlaeggningar genom katalytisk reburning

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, F.A. [Katator AB, Lund (Sweden)

    2000-03-01

    A study concerning the possibility of using catalytic reburning in the abatement of nitrogen oxides from bio-fuelled combustion units has been accomplished. In catalytic reburning, the fuel is combusted at a low excess-air-ratio to minimize the necessary amount of reburning gas added downstream the combustion chamber. The reburning fuel (a reducing agent, e.g. natural gas or LPG) will react catalytically with oxygen and nitrogen oxides in the reburning catalyst to produce carbon oxides, water and nitrogen. Secondary air is injected downstream the reburning catalyst to facilitate an effective combustion of remaining CO and hydrocarbons in the oxidation catalyst, usually in a tail-end position. Experiments were carried out in a small-scale combustion unit (10-20 kW{sub fuel} for pellets of bio-fuel). The results indicate possible conversion degrees of 90% with respect to nitrogen oxides, without increased emissions of CO and hydrocarbons. The economic evaluation indicates a great sensitivity to the price of the reburning fuel. Problems with uneven flow conditions and concentration gradients are expected to reduce the performance of catalytic reburning. Damages caused by corrosion at low oxygen concentrations are likely to occur in positions with high metal temperatures, e.g. in the super-heater-portion of the flue-gas-channel. Hydrocarbon-SCR is an alternative method to obtain a reasonable reduction of the emissions of nitrogen oxides. Small amounts of certain hydrocarbons (e.g. LPG) are added to the flue-gas-stream at a normal excess-air-ratio to obtain a conversion degree of 50 - 70% over a transition-metal-exchanged zeolite catalyst. Continued experiments should focus on installations in large bio-fuelled appliances, where a detailed technical and economical evaluation is possible. Especially catalyst deactivation needs to be evaluated further.

  18. Eliminating cracking during drying

    CERN Document Server

    Jin, Qiu; Schofield, Andrew B; Xu, Lei; 10.1140/epje/i2013-13028-9

    2013-01-01

    When colloidal suspensions dry, stresses build up and cracks often occur - a phenomenon undesirable for important industries such as paint and ceramics. We demonstrate an effective method which can completely eliminate cracking during drying: by adding emulsion droplets into colloidal suspensions, we can systematically decrease the amount of cracking, and eliminate it completely above a critical droplet concentration. Since the emulsion droplets eventually also evaporate, our technique achieves an effective function while making little changes to the component of final product, and may therefore serve as a promising approach for cracking elimination. Furthermore, adding droplets also varies the speed of air invasion and provides a powerful method to adjust drying rate. With the effective control over cracking and drying rate, our study may find important applications in many drying and cracking related industrial processes.

  19. Elevated temperature crack growth

    Science.gov (United States)

    Kim, K. S.; Vanstone, R. H.

    1992-01-01

    The purpose of this program was to extend the work performed in the base program (CR 182247) into the regime of time-dependent crack growth under isothermal and thermal mechanical fatigue (TMF) loading, where creep deformation also influences the crack growth behavior. The investigation was performed in a two-year, six-task, combined experimental and analytical program. The path-independent integrals for application to time-dependent crack growth were critically reviewed. The crack growth was simulated using a finite element method. The path-independent integrals were computed from the results of finite-element analyses. The ability of these integrals to correlate experimental crack growth data were evaluated under various loading and temperature conditions. The results indicate that some of these integrals are viable parameters for crack growth prediction at elevated temperatures.

  20. Syntheses, characterizations, and catalytic activities of mesostructured aluminophosphates with tailorable acidity assembled with various preformed zeolite nanoclusters

    KAUST Repository

    Suo, Hongri

    2015-02-25

    © 2015, Springer Science+Business Media New York. A series of ordered hexagonal mesoporous zeolites have been successfully synthesized by the assembly of various preformed aluminosilicates zeolite (MFI, FAU, BEA etc.) with surfactants (cetyltrimethylammonium chloride) under hydrothermal conditions. These unique samples were further characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption, infrared spectroscopy. Characterization results showed that these samples contain primary and secondary structural building units of various zeolites, which may be responsible for their distinguished acidic strength, suggesting that the acidic strength of these mesoporous silicoaluminophosphates could be tailored and controlled. Furthermore, the prepared samples were catalytically active in the cracking of cumene.

  1. Effect of crack propagation on crack tip fields

    Directory of Open Access Journals (Sweden)

    F.V. Antunes

    2013-07-01

    Full Text Available Crack closure influences fatigue crack growth rate and must be included in the design of components. Plasticity induced crack closure is intimately linked with the crack tip plastic deformation, which becomes residual as the crack propagates. The objective here is to study numerically the effect of crack propagation on crack tip fields. The transient effect observed at the beginning of crack propagation is linked to the hardening behavior of material. The effect of mesh refinement is studied, and a singular behavior is evident, which is explained by the sharp crack associated with mesh topology, composed of a regular pattern of square elements. The plastic zone size measured perpendicularly to crack flank in the residual plastic wake is quantified and compared with literature models. Finally, the removal of material at the first node behind crack tip with load cycling was observed for plane strain state and some hardening models in plane stress state.

  2. Synthesis and characterization of type silicoaluminophosphates catalytic support; Sintese e caracterizacao de suportes cataliticos do tipo silicoaluminofosfatico

    Energy Technology Data Exchange (ETDEWEB)

    Leite, C.E.T.; Carvalho, M.W.N.C.; Pereira, K.R.O., E-mail: carlosedisio@hotmail.co [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica. Lab. de Catalise, Adsorcao e Biocombustiveis

    2010-07-01

    The refining processes, the catalytic hydrocracking is the future of diesel oil in Brazil and the first units are already scheduled to be inaugurated. Among the catalysts used in this process, silicoaluminophosphates (SAPO's) have considerable potential for use as they have been effective in the isomerization of n-alkanes, the isomerization of olefins and alkylation of aromatics. Because of this, the objective is to develop catalysts that will be used in hydrocracking reactions. The media like SAPO-5 were synthesized with different ratios silicon/aluminum, which is used as a catalytic support and have the function of crack organic molecules, since it has acidic character. The materials were characterized by techniques: X-ray diffraction, chemical analysis and textural by BET. After summarizing the media found that they had agreements with the crystalline phases presented in the literature.(author)

  3. Quantity effect of radial cracks on the cracking propagation behavior and the crack morphology.

    Directory of Open Access Journals (Sweden)

    Jingjing Chen

    Full Text Available In this letter, the quantity effect of radial cracks on the cracking propagation behavior as well as the circular crack generation on the impacted glass plate within the sandwiched glass sheets are experimentally investigated via high-speed photography system. Results show that the radial crack velocity on the backing glass layer decreases with the crack number under the same impact conditions during large quantities of repeated experiments. Thus, the "energy conversion factor" is suggested to elucidate the physical relation between the cracking number and the crack propagation speed. Besides, the number of radial crack also takes the determinative effect in the crack morphology of the impacted glass plate. This study may shed lights on understanding the cracking and propagation mechanism in laminated glass structures and provide useful tool to explore the impact information on the cracking debris.

  4. Bifunctional catalytic electrode

    Science.gov (United States)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  5. Modelling of Corrosion Cracks

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.......Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed....

  6. Reactivity of organic compounds in catalytic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minachev, Kh.M.; Bragin, O.V.

    1978-01-01

    A comprehensive review of 1976 Soviet research on catalysis delivered to the 1977 annual session of the USSR Academy of Science Council on Catalysis (Baku 6/16-20/77) covers hydrocarbon reactions, including hydrogenation and hydrogenolysis, dehydrogenation, olefin dimerization and disproportionation, and cyclization and dehydrocyclization (e.g., piperylene cyclization and ethylene cyclotrimerization); catalytic and physicochemical properties of zeolites, including cracking, dehydrogenation, and hydroisomerization catalytic syntheses and conversion of heterocyclic and functional hydrocarbon derivatives, including partial and total oxidation (e.g., of o-xylene to phthalic anhydride); syntheses of thiophenes from alkanes and hydrogen sulfide over certain dehydrogenation catalysts; catalytic syntheses involving carbon oxides ( e.g., the development of a new heterogeneous catalyst for hydroformylation of olefins), and of Co-MgO zeolitic catalysts for synthesis of aliphatic hydrocarbons from carbon dioxide and hydrogen, and fabrication of high-viscosity lubricating oils over bifunctional aluminosilicate catalysts.

  7. Investigation and evaluation of cracking incidents in piping in pressurized water reactors. Technical report

    International Nuclear Information System (INIS)

    This report summarizes an investigation of known cracking incidents in pressurized water reactor plants. Several instances of cracking in feedwater piping in 1979, together with reported cases of stress corrosion cracking at Three Mile Island Unit 1, led to the establishment of the third Pipe Crack Study Group. Major differences between the scope of the third PCSG and the previous two are: (1) the emphasis given to systems safety implications of cracking, and (2) the consideration given all cracking mechanisms known to affect PWR piping, including the failure of small lines in secondary safety systems. The present PCSG reviewed existing information on cracking of PWR pipe systems, either contained in written records of collected from meetings in the United States, and made recommendations in response to the PCSG charter questions and to othe major items that may be considered to either reduce the potential for cracking or to improve licensing bases

  8. Computer Simulations of the Fatigue Crack Propagation

    Directory of Open Access Journals (Sweden)

    A. Materna

    2000-01-01

    Full Text Available The following hypothesis for design of structures based on the damage tolerance philosophy is laid down: the perpendicular fatigue crack growth rate v in a certain point of a curved crack front is given by the local value of stress intensity factor per unit of nominal stress K' and the local triaxiality T which describes the constraint. The relationship v = f (K', T is supposed to be typical for a given loading spectrum and material. Such relationship for a 2024 Al alloy and the flight-simulation spectrum was derived from the fatigue test of the rectangular panel with the central hole and used for three-dimensional simulation of the corner fatigue crack propagation in the model of the wing spar flangeplate. Finite element and boundary element methods were used for these computations. The results of the simulation are in good agreement with the experiment.

  9. Identification of breathing cracks in a beam structure with entropy

    Science.gov (United States)

    Wimarshana, Buddhi; Wu, Nan; Wu, Christine

    2016-04-01

    A cantilever beam with a breathing crack is studied to detect and evaluate the crack using entropy measures. Closed cracks in engineering structures lead to proportional complexities to their vibration responses due to weak bi-linearity imposed by the crack breathing phenomenon. Entropy is a measure of system complexity and has the potential in quantifying the complexity. The weak bi-linearity in vibration signals can be amplified using wavelet transformation to increase the sensitivity of the measurements. A mathematical model of harmonically excited unit length steel cantilever beam with a breathing crack located near the fixed end is established, and an iterative numerical method is applied to generate accurate time domain dynamic responses. The bi-linearity in time domain signals due to the crack breathing are amplified by wavelet transformation first, and then the complexities due to bi-linearity is quantified using sample entropy to detect the possible crack and estimate the crack depth. It is observed that the method is capable of identifying crack depths even at very early stages of 3% with the increase in the entropy values more than 10% compared with the healthy beam. The current study extends the entropy based damage detection of rotary machines to structural analysis and takes a step further in high-sensitivity structural health monitoring by combining wavelet transformation with entropy calculations. The proposed technique can also be applied to other types of structures, such as plates and shells.

  10. Hexane cracking over steamed phosphated zeolite H-ZSM-5 : Promotional effect on catalyst performance and stability

    NARCIS (Netherlands)

    Van Der Bij, Hendrik E.; Meirer, Florian; Kalirai, Samanbir; Wang, Jian; Weckhuysen, Bert M.

    2014-01-01

    The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of 27Al and 31P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3 tempera

  11. Statistical crack mechanics

    International Nuclear Information System (INIS)

    Although it is possible to simulate the ground blast from a single explosive shot with a simple computer algorithm and appropriate constants, the most commonly used modelling methods do not account for major changes in geology or shot energy because mechanical features such as tectonic stresses, fault structure, microcracking, brittle-ductile transition, and water content are not represented in significant detail. An alternative approach for modelling called Statistical Crack Mechanics is presented in this paper. This method, developed in the seventies as a part of the oil shale program, accounts for crack opening, shear, growth, and coalescence. Numerous photographs and micrographs show that shocked materials tend to involve arrays of planar cracks. The approach described here provides a way to account for microstructure and give a representation of the physical behavior of a material at the microscopic level that can account for phenomena such as permeability, fragmentation, shear banding, and hot-spot formation in explosives

  12. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  13. Study and Analysis on Naphtha Catalytic Reforming Reactor Simulation

    Institute of Scientific and Technical Information of China (English)

    Liang Ke min; Song Yongji; Pan Shiwei

    2004-01-01

    A naphtha catalytic reforming unit with four reactors connected in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reaction characteristics based on idealizing the complex naphtha mixture to represent the paraffin, naphthene, and aromatic groups with individual compounds. The simulation results based on above models agree very well with actual operating data of process unit.

  14. A study on naphtha catalytic reforming reactor simulation and analysis

    Institute of Scientific and Technical Information of China (English)

    LIANG Ke-min; GUO Hai-yan; PAN Shi-wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  15. Crack detection '86

    International Nuclear Information System (INIS)

    The participants of the conference heard 36 papers of which 13 were incorporated in INIS. The incorporated papers deal with the quality control of the equipment of nuclear power plants, with technical specifications and possibilities of diverse crack detection devices, as well as with personnel training for nondestructive materials testing. (E.S.)

  16. Monitoring of solidification crack propagation mechanism in pulsed laser welding of 6082 aluminum

    Science.gov (United States)

    von Witzendorff, P.; Kaierle, S.; Suttmann, O.; Overmeyer, L.

    2016-03-01

    Pulsed laser sources with pulse durations in the millisecond regime can be used for spot welding and seam welding of aluminum. Seam welds are generally produced with several overlapping spot welds. Hot cracking has its origin in the solidification process of individual spot welds which determines the cracking morphology along the seam welding. This study used a monitoring unit to capture the crack geometry within individual spot welds during seam welding to investigate the conditions for initiation, propagation and healing (re-melting) of solidification cracking within overlapping pulsed laser welds. The results suggest that small crack radii and high crack angles with respect to welding direction are favorable conditions for crack healing which leads to crack-free seam welds. Optimized pulse shapes were used to produce butt welds of 0.5 mm thick 6082 aluminum alloys. Tensile tests were performed to investigate the mechanical strength in the as-welded condition.

  17. Neural crack identification

    International Nuclear Information System (INIS)

    The inverse, crack identification problem in elasticity can be formulated as an output error minimization problem which, nevertheless, can not be solved without difficulties by classical numerical optimization. A review of all these previous results, where we used neural networks, filter-driven optimization and genetic algorithms is presented and in a companion lecture during this conference. The use of neural networks for the solution of the inverse problem makes possible the on-line solution of the problem. In fact, one usually approximates the inverse mapping (measurements versus crack quantities). Most of the effort is spent for the learning of this relation, while a sufficiently trained neural network provides predictions with, practically, zero computational cost. Potential applications include on-line, in-flight health monitoring systems with applications in civil and mechanical engineering and production control. In this paper we present new developments in the design of specialized neural networks for the solution of the crack identification problem. Emphasis is posed on the effective use of the learning data, which are produced by the boundary element method. Several technical data will be discussed. They include thoughts about the effective choice of the neural network architecture, the number of training examples and of the learning algorithms will be provided, together with the results of our recent numerical investigation. A detailed application for one or more elliptical cracks using static analysis results with the use of back-propagation trained neural networks will be provided. The general methodology follows our previously published results. By using more refined algorithms for the numerical solution of the neural network learning problem, which are based on the MERLIN optimization system developed in the department of the second author, we are able to solve complicated tasks. First results based on dynamic investigations (wave propagation driven

  18. Crack patterns over uneven substrates.

    Science.gov (United States)

    Nandakishore, Pawan; Goehring, Lucas

    2016-02-28

    Cracks in thin layers are influenced by what lies beneath them. From buried craters to crocodile skin, crack patterns are found over an enormous range of length scales. Regardless of absolute size, their substrates can dramatically influence how cracks form, guiding them in some cases, or shielding regions from them in others. Here we investigate how a substrate's shape affects the appearance of cracks above it, by preparing mud cracks over sinusoidally varying surfaces. We find that as the thickness of the cracking layer increases, the observed crack patterns change from wavy to ladder-like to isotropic. Two order parameters are introduced to measure the relative alignment of these crack networks, and, along with Fourier methods, are used to characterise the transitions between crack pattern types. Finally, we explain these results with a model, based on the Griffith criteria of fracture, that identifies the conditions for which straight or wavy cracks will be seen, and predicts how well-ordered the cracks will be. Our metrics and results can be applied to any situation where connected networks of cracks are expected, or found. PMID:26762761

  19. In service measurement of a process media distribution by using a sealed gammer-ray source (60Co) at the catalyst riser of the fluid catalytic cracking unit (FCCU) in a petroleum refinery

    International Nuclear Information System (INIS)

    Gamma scans were performed on a catalyst riser of FCCU in service by using a sealed gamma-ray source 60Co and an automatic gamma scanner, specifically designed for a protection against a high heat for the purpose of an investigation the fluidized pattern of a catalyst. The internal media which was composed of the catalyst, the heavy oil, and steam was distributed homogeneously and impurities such as deposited coke were not found at the lower part of the region connected to the nozzles. However, some suspicious zones which were considered as abnormal conditions were detected between the steel grating and the nozzles. Generally the amount of media distribution at the lower part of the riser was larger than that of the upper part. From this experiment by using a gamma source, the conditions of a media distribution were identified and any abnormal areas were successfully localized.

  20. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    Directory of Open Access Journals (Sweden)

    Vedi V.E.

    2012-12-01

    Full Text Available The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  1. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    OpenAIRE

    Vedi V.E.; Rovenskii A.I.

    2012-01-01

    The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  2. Catalytic pyrolysis of waste rice husk over mesoporous materials

    Science.gov (United States)

    2012-01-01

    Catalytic fast pyrolysis of waste rice husk was carried out using pyrolysis-gas chromatography/mass spectrometry [Py-GC/MS]. Meso-MFI zeolite [Meso-MFI] was used as the catalyst. In addition, a 0.5-wt.% platinum [Pt] was ion-exchanged into Meso-MFI to examine the effect of Pt addition. Using a catalytic upgrading method, the activities of the catalysts were evaluated in terms of product composition and deoxygenation. The structure and acid site characteristics of the catalysts were analyzed by Brunauer-Emmett-Teller surface area measurement and NH3 temperature-programmed desorption analysis. Catalytic upgrading reduced the amount of oxygenates in the product vapor due to the cracking reaction of the catalysts. Levoglucosan, a polymeric oxygenate species, was completely decomposed without being detected. While the amount of heavy phenols was reduced by catalytic upgrading, the amount of light phenols was increased because of the catalytic cracking of heavy phenols into light phenols and aromatics. The amount of aromatics increased remarkably as a result of catalytic upgrading, which is attributed to the strong Brönsted acid sites and the shape selectivity of the Meso-MFI catalyst. The addition of Pt made the Meso-MFI catalyst even more active in deoxygenation and in the production of aromatics. PMID:22221540

  3. Modified Dugdale crack models - some easy crack relations

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    ) by a constant flow stress (sigma_L). A number of materials, however, do not at all exhibit this kind of flow. Such materials are considered in this paper by Modified Dugdale crack models which apply for any cohesive stress distribution in crack front areas. Formally modified Dugdale crack models exhibit......The Dugdale crack model is widely used in materials science to predict strength of defective (cracked) materials. A stable Dugdale crack in an elasto-plastic material is prevented from spreading by uniformly distributed cohesive stresses acting in narrow areas at the crack tips. These stresses......_Ldelta_CR where sigma_L is strength, and at the same time constant flow stress, of the uncracked material while delta_CR is flow limit (displacement).Obviously predictions by the Dugdale model are most reliable for materials with stress-strain relations where flow can actually be described (or well approximated...

  4. 催化干气回收乙烯装置中脱碳塔内件形式优化改造%Optimal Modification of Internals in Decarbonization Column of Catalytic Dry Gas Ethylene Recovery Unit

    Institute of Scientific and Technical Information of China (English)

    刘玉花

    2016-01-01

    脱碳塔是影响催化干气回收乙烯装置处理量的瓶颈。装置低负荷运行时脱碳塔操作平稳,而负荷升高时塔顶部分液罐中液位升高,操作不正常,净化气带胺液跑损严重。分析了脱碳塔的特殊性,结合现场操作存在问题,选用消泡型内件及填料对脱碳塔进行改造,改造后装置操作弹性增加,处理能力提高,脱碳塔胺液夹带现象明显降低,胺液补充量显著减少,经济效益显著,可为类似系统内件改造提供借鉴。%Decarbonization column is the bottleneck which affecting the capacity of the catalytic dry gas ethylene recovery unit.When the unit operating in low load,the decarbonization column under steady state.However,when the operation load increase,the liquid level of the liquid sep-arate pot will rise and the operation state gets bad.The particularity of decarbonization column is analyzed and combined with the problems encountered in actual operating situation,and the opti-mal modification of the internals in decarbonization column is put forward.Through selecting the defoaming internals and modifying,the flexibility of the operation and the capacity of the unit is increased.Moreover,the amine liquid consumption is decreased obviously and the economic bene-fit is remarkable.An important reference for the similar device is provided.

  5. Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation

    KAUST Repository

    Imran, Ali

    2016-03-11

    Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liquid yield due to the increased production of non-condensables, primarily hydrocarbons. The catalytically produced bio-oil was less viscous and zeolites were effective at cracking heavy molecular weight compounds in the bio-oil. Acidic zeolites, H-Y and H-ZSM5, increased the desirable chemical compounds in the bio-oil such as phenols, furans and hydrocarbon, and reduced the undesired compounds such as acids. On the other hand reducing the acidity of zeolites reduced some of the undesired compounds in the bio-oil such as ketones and aldehydes. The performance of H-Y was superior to that of the rest of zeolites studied: bio-oil of high chemical and calorific value was produced with a high organic liquid yield and low oxygen content. H-ZSM5 was a close competitor to H-Y in performance but with a lower yield of bio-oil. Online fractionation of catalytic pyrolysis vapors was employed by controlling the condenser temperature and proved to be a successful process parameter to tailor the

  6. 生物质焦油催化裂解过程中酸性催化剂积碳失活与烧焦再生特性%Deactivation and Burning Regeneration of Coked Acid Catalysts in Catalytic Cracking Process of Biomass Tar

    Institute of Scientific and Technical Information of China (English)

    李永玲; 吴占松

    2014-01-01

    为了研究酸性催化剂积碳失活以及再生特性,在固定床反应器上,以高铝砖作为催化剂,进行了生物质焦油催化裂解实验。实验结果表明,由于催化剂表面积碳,造成催化剂活性随着作用时间增加而下降。但当催化剂工作一定时间后,催化剂表面的积碳速率开始变得平缓,单层积碳向多层积碳转变。当积碳速率与反应中焦炭脱除速率达到平衡时,催化剂表面积碳量将趋于稳定。实验中采用烧焦法有效地恢复了催化剂的活性,但是焦炭燃烧会破坏催化剂表面的酸性结构,减少表面活化位,使得再生后的催化剂并不能完全达到新鲜催化剂所具有的催化能力。而且烧焦再生过程中会发生烧结,结晶等现象,改变催化剂的孔隙率、孔径分布、比表面积等物理特性。%In order to study the activity regeneration of deactivating acid catalysts with carbon deposition, the catalytic cracking experiments on biomass tar were carried out in a fixed bed reactor with high-alumina brick as acid catalyst. The results show that the catalyst activity declines with the increase of reaction time, due to the carbon depositing on catalyst surface. The carbon depositing rate on catalyst surface becomes smooth after a period of work time, and the mode of coke deposition becomes multi-layer form monolayer. The quantities of the carbon depositing on the catalyst surface will be stable, when the coking rate is equal to the rate of coke consumption. The regeneration method of coke burning can effectively recover the activity of catalyst. But the activity of regenerated catalyst cannot be the same as that of fresh catalyst, because the acidic structure and active center on catalyst surface are destroyed in coke combustion process. In addition, the sintering or crystallization phenomenon will occur in catalysts regeneration process with coke burning, which may change the physical

  7. Subcritical crack growth in marble

    Science.gov (United States)

    Nara, Yoshitaka; Nishida, Yuki; Toshinori, Ii; Harui, Tomoki; Tanaka, Mayu; Kashiwaya, Koki

    2016-04-01

    It is essential to study time-dependent deformation and fracturing in various rock materials to prevent natural hazards related to the failure of a rock mass. In addition, information of time-dependent fracturing is essential to ensure the long-term stability of a rock mass surrounding various structures. Subcritical crack growth is one of the main causes of time-dependent fracturing in rock. It is known that subcritical crack growth is influenced by not only stress but also surrounding environment. Studies of subcritical crack growth have been widely conducted for silicate rocks such as igneous rocks and sandstones. By contrast, information of subcritical crack growth in carbonate rocks is not enough. Specifically, influence of surrounding environment on subcritical crack growth in carbonate rock should be clarified to ensure the long-term stability of a rock mass. In this study, subcritical crack growth in marble was investigated. Especially, the influence of the temperature, relative humidity and water on subcritical crack growth in marble is investigated. As rock samples, marbles obtained in Skopje-City in Macedonia and Carrara-City in Italy were used. To measure subcritical crack growth, we used the load relaxation method of the double-torsion (DT) test. All measurements by DT test were conducted under controlled temperature and relative humidity. For both marbles, it was shown that the crack velocity in marble in air increased with increasing relative humidity at a constant temperature. Additionally, the crack velocity in water was much higher than that in air. It was also found that the crack velocity increased with increasing temperature. It is considered that temperature and water have significant influences on subcritical crack growth in marble. For Carrara marble in air, it was recognized that the value of subcritical crack growth index became low when the crack velocity was higher than 10-4 m/s. This is similar to Region II of subcritical crack growth

  8. 80万吨重油催化装置能量回收三机组扩能设计%80 million tons of heavy fuel oil catalytic unit three joint machine of energy recovery rectisol design

    Institute of Scientific and Technical Information of China (English)

    崔常鹏

    2011-01-01

    介绍了80万吨重油催化装置能量回收三机组扩能设计及节能效果."三机组"是烟气轮机、轴流风机和电动机组.为了确保重油催化装置扩能后能耗匹配,对三机组进行了扩能设计.轴流机在三机组里与烟气轮机同轴,其安全性及可靠性直接影响烟气轮机的运行.依据烟气轮机的最大负荷,确定了烟气轮机的设计方案;按照烟气轮机的最大轴功率,确定了轴流风机的扩能方案,并对其配套系统进行了优化设计,实现了预期的节能目的.%The introduces 80 million tons of heavy fuel oil catalytic unit three joint machine of energy recovery of rectisol design methods and obtain energy saving effects. Three joint machine of energy recovery device means smoke turbo-generator-axial flow fans-electric (power)unit. In order to guarantee device matching, energy recovery machine also were designed capacity. Axial flow machine and smoke turbogenerator coaxial. The safety and reliability of axial flow machine directly affect smoke turbo-generator.Through the largest load calculation,determines the design scheme of the smoke turbo-generator;Meanwhile ,according to the biggest shaft power smoke turbo-generator, Checking shaft head of axial flow fans exhaust end strength,determines the design scheme of axial flow fans ,and the supporting system was reformed. the capacity is expected to reach energy-saving effect.

  9. Elastoplastic analysis for infinite plate with centric crack loaded by two pairs of point shear forces

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-ping; LING Tong-hua

    2005-01-01

    The near crack line analysis method was used to investigate a crack loaded by two pairs of point shear forces in an infinite plate in an elastic-perfectly plastic solid, and the analytical solution was obtained. The solutions include: the unit normal vector of the elastic-plastic boundary near the crack line, the elastic-plastic stress fields near crack line, law that the length of the plastic zone along the crack line is varied with an external loads, and the bearing capacity of an infinite plate with a center crack loaded by two pairs of point shear forces. The results are sufficiently precise near the crack line because the assumptions of the small scale yielding theory have not been made and no other assumption have been taken.

  10. Adaptive Wavelet Transform Method to Identify Cracks in Gears

    Directory of Open Access Journals (Sweden)

    Ales Belsak

    2010-01-01

    Full Text Available Many damages and faults can cause problems in gear unit operation. A crack in the tooth root is probably the least desirable among them. It often leads to failure of gear unit operation. By monitoring vibrations, it is possible to determine the presence of a crack. Signals are, however, very noisy. This makes it difficult to define properties of individual components. Wavelet analysis is an effective tool for analysing signals and for defining properties. In this paper, a denoising method based on wavelet analysis, which takes prior information about impulse probability density into consideration, is used to identify transient information from vibration signals of a gear unit with a fatigue crack in the tooth root.

  11. Cryptography cracking codes

    CERN Document Server

    2014-01-01

    While cracking a code might seem like something few of us would encounter in our daily lives, it is actually far more prevalent than we may realize. Anyone who has had personal information taken because of a hacked email account can understand the need for cryptography and the importance of encryption-essentially the need to code information to keep it safe. This detailed volume examines the logic and science behind various ciphers, their real world uses, how codes can be broken, and the use of technology in this oft-overlooked field.

  12. Study on Synthesis and Catalytic Performance of Hierarchical Zeolite

    Institute of Scientific and Technical Information of China (English)

    Zhang Lingling; Li Fengyan; ZhaoTianbo; Sun Guida

    2007-01-01

    A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method.X-ray diffraction (XRD)and nitrogen adsorption-desorption method were used to study the phase and aperture structure of the prepared catalyst.Infrared(IR)spectra of pyridine adsorbed on the sample showed that the hierarchical zeolite really had much more Bronsted and Lewis acidic sites than the HZSM-5 zeolite.The catalytic cracking of large hydrocarbon molecules showed that the hierarchical zeolite had a higher catalytic activity than the HZSM-5 zeolite.

  13. Catalytic distillation structure

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  14. Catalytic combustor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mercea, J.; Grecu, E.; Fodor, T.; Kreibik, S.

    1982-01-01

    The performance of catalytic combustors for hydrogen using platinum-supported catalysts is described. Catalytic plates of different sizes were constructed using fibrous and ceramic supports. The temperature distribution as well as the reaction efficiency as a function of the fuel input rate was determined, and a comparison between the performances of different plates is discussed.

  15. Acidic and basic properties of zeolite-containing cracking catalyst in the process of butene-1 isomerization

    Science.gov (United States)

    Mursalova, L. A.; Guseinova, E. A.; Adzhamov, K. Yu.

    2016-08-01

    The process of butene-1 isomerization in the presence of two groups of samples of zeolite-containing catalyst (ZCC) that earlier participated in the traditional and oxidative catalytic cracking of vacuum gasoil is investigated. It is established that the nature of the reaction mixture and conditions of the cracking process are key factors in forming the acidic and basic properties of the catalyst. It is shown that the highest activity in the butene-1 isomerization into cis-/ trans-butene-2 is demonstrated by ZCC samples that participated in the oxidative catalytic cracking (oxycracking). It is suggested that the enhanced catalytic activity of this group of ZCC samples was related to the availability of acid-base centers in the form of radical-like oxygen along with protic- and aprotic-type acidic centers in the structure of the oxidative compaction products.

  16. Experiences on IGSCC crack manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Veron, P. [Equipos Nucleares, S.A., Maliano (Spain)

    1997-02-01

    The author presents his experience in manufacturing IGSCC realistic defects, mainly in INCONEL 600 MA Steam Generator Tubes. From that experience he extracts some knowledge about this cracking (influence of chemistry in the environment, stress state, crack growth rate, and occurrence in laboratory condition of break before leak).

  17. Decomposition of tar in gas from updraft gasifier by thermal cracking

    DEFF Research Database (Denmark)

    Brandt, Peder; Henriksen, Ulrik Birk

    2000-01-01

    Continuing earlier work with tar reduction by partial oxidation of pyrolysis gas [1] thermal cracking has been evaluated as a gas cleaning process. The work has been focusing on cleaning gas from updraft gasifiers, and the long term purpose is to develop a tar cleaning unit based on thermal crack...

  18. A consistent partly cracked XFEM element for cohesive crack growth

    DEFF Research Database (Denmark)

    Asferg, Jesper L.; Poulsen, Peter Noe; Nielsen, Leif Otto

    2007-01-01

    capable of modelling variations in the discontinuous displacement field on both sides of the crack and hence also capable of modelling the case where equal stresses are present on each side of the crack. The enrichment was implemented for the 3-node constant strain triangle (CST) and a standard algorithm...... was used to solve the non-linear equations. The performance of the element is illustrated by modelling fracture mechanical benchmark tests. Investigations were carried out on the performance of the element for different crack lengths within one element. The results are compared with previously obtained...

  19. Hexane cracking over steamed phosphated zeolite H-ZSM-5: promotional effect on catalyst performance and stability.

    Science.gov (United States)

    van der Bij, Hendrik E; Meirer, Florian; Kalirai, Sam; Wang, Jian; Weckhuysen, Bert M

    2014-12-15

    The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of (27) Al and (31) P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3 temperature-programmed desorption and N2 physisorption. Phosphated H-ZSM-5 retains more acid sites and catalytic cracking activity after steam treatment than its non-phosphated counterpart, while the selectivity towards propylene is improved. It was established that the stabilization effect is twofold. First, the local framework silico-aluminophosphate (SAPO) interfaces, which form after phosphatation, are not affected by steam and hold aluminum atoms fixed in the zeolite lattice, preserving the pore structure of zeolite H-ZSM-5. Second, the four-coordinate framework aluminum can be forced into a reversible sixfold coordination by phosphate. These species remain stationary in the framework under hydrothermal conditions as well. Removal of physically coordinated phosphate after steam-treatment leads to an increase in the number of strong acid sites and increased catalytic activity. We propose that the improved selectivity towards propylene during catalytic cracking can be attributed to local SAPO interfaces located at channel intersections, where they act as impediments in the formation of bulky carbenium ions and therefore suppress the bimolecular cracking mechanism. PMID:25370739

  20. Hexane cracking over steamed phosphated zeolite H-ZSM-5: promotional effect on catalyst performance and stability.

    Science.gov (United States)

    van der Bij, Hendrik E; Meirer, Florian; Kalirai, Sam; Wang, Jian; Weckhuysen, Bert M

    2014-12-15

    The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of (27) Al and (31) P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3 temperature-programmed desorption and N2 physisorption. Phosphated H-ZSM-5 retains more acid sites and catalytic cracking activity after steam treatment than its non-phosphated counterpart, while the selectivity towards propylene is improved. It was established that the stabilization effect is twofold. First, the local framework silico-aluminophosphate (SAPO) interfaces, which form after phosphatation, are not affected by steam and hold aluminum atoms fixed in the zeolite lattice, preserving the pore structure of zeolite H-ZSM-5. Second, the four-coordinate framework aluminum can be forced into a reversible sixfold coordination by phosphate. These species remain stationary in the framework under hydrothermal conditions as well. Removal of physically coordinated phosphate after steam-treatment leads to an increase in the number of strong acid sites and increased catalytic activity. We propose that the improved selectivity towards propylene during catalytic cracking can be attributed to local SAPO interfaces located at channel intersections, where they act as impediments in the formation of bulky carbenium ions and therefore suppress the bimolecular cracking mechanism.

  1. Probabilistic Analysis of Crack Width

    Directory of Open Access Journals (Sweden)

    J. Marková

    2000-01-01

    Full Text Available Probabilistic analysis of crack width of a reinforced concrete element is based on the formulas accepted in Eurocode 2 and European Model Code 90. Obtained values of reliability index b seem to be satisfactory for the reinforced concrete slab that fulfils requirements for the crack width specified in Eurocode 2. However, the reliability of the slab seems to be insufficient when the European Model Code 90 is considered; reliability index is less than recommended value 1.5 for serviceability limit states indicated in Eurocode 1. Analysis of sensitivity factors of basic variables enables to find out variables significantly affecting the total crack width.

  2. Catalytic distillation process

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  3. Catalytic Functions of Standards

    NARCIS (Netherlands)

    K. Blind (Knut)

    2009-01-01

    textabstractThe three different areas and the examples have illustrated several catalytic functions of standards for innovation. First, the standardisation process reduces the time to market of inventions, research results and innovative technologies. Second, standards themselves promote the diffusi

  4. A computational algorithm for crack determination: The multiple crack case

    Science.gov (United States)

    Bryan, Kurt; Vogelius, Michael

    1992-01-01

    An algorithm for recovering a collection of linear cracks in a homogeneous electrical conductor from boundary measurements of voltages induced by specified current fluxes is developed. The technique is a variation of Newton's method and is based on taking weighted averages of the boundary data. The method also adaptively changes the applied current flux at each iteration to maintain maximum sensitivity to the estimated locations of the cracks.

  5. Cracking conditions of crude oil under different geological environments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    There are mainly 3 kinds of existing states of oil generating from source rocks,that is,dispersive liquid hydrocarbon inside of source rock,dispersive liquid hydrocarbon outside of source rock and concentrated liquid hydrocarbon outside of source rock.Because of the differences in thermal history and medium conditions around,and the interaction of organic and inorganic matter,the liquid hydrocarbon with 3 kinds of existing state has different cracking conditions.The gas generation dynamics experiments of crude oil matching different mediums indicate that the distribution of activation energy of methane changes a lot according to medium difference.The carbonate has a main influence on oil cracking conditions and can largely reduce its activation energy,which reflects the lower cracking temperature of crude oil.The mudstone takes a second place and the sandstone is the smallest.The catalytic cracking function to the oil of the carbonate,of the mudstone and of the sandstone changes weaken in turn.The corresponding Ro values of main gas generation period in different mediums are as follows:1.5%―3.8%with pure crude oil,1.2%―3.2%with dispersive crude oil in carbonate,1.3%~3.4% with dispersive crude oil in mudstone and 1.4%―3.6%with dispersive crude oil in sandstone.The influence of pressure to crude oil cracking is relatively complicated.In the low heating speed condition, pressure restrains the oil cracking and gas generation,but in the high heating speed condition,pressure has an indistinctive influence to the oil cracking and gas generation.Pressure also makes a different effort in different evolvement stage.Taking the middle and lower Cambrian source rocks in the Tarim Basin as an example,primary oil generating quantity is 2232.24×10 8 t,residual oil and oil cracking gas quantity is 806.21×10 8 t and 106.95×10 12 m 3 respectively.

  6. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    K. L. Hohn; C.-C. Huang; C. Cao

    2009-01-01

    Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

  7. Commercial Application of RMC Technology in the 1.5 Mt/a Hydrocracking Unit at Shanghai Petrochemical Company

    Institute of Scientific and Technical Information of China (English)

    Xiong Zhenlin; Wang Yiguan; Zhang Maoying; Lin Baohua; Mao Yichao

    2003-01-01

    The RMC technology developed by RIPP has been applied in a 1.5 Mt/a medium pressure hydrocracking unit at Shanghai Petrochemical Company. The unit was successfully put on stream in September 2002. Calibration of the performance of the commercial unit has shown that the RMC technology has higher hydrogenation activity and selectivity, and high quality product can be obtained under lower reaction temperature. The heavy naphtha with less than 0.5 ppm of sulfur and 58.5 m% potential aromatic content is a good feedstock for catalytic reforming unit. The diesel with less than 0.5 ppm of sulfur, 6.6 m% aromatics and cetane rating of 56 is a high-grade diesel fuel. The hydrocracked tail oil containing more than 14 m% hydrogen and mere 1.7m% aromatics could be used as a good feedstock for steam cracking process to produce ethylene.

  8. Peridynamic model for fatigue cracking.

    Energy Technology Data Exchange (ETDEWEB)

    Silling, Stewart Andrew; Abe Askari (Boeing)

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the "remaining life" of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  9. Peridynamic model for fatigue cracking.

    Energy Technology Data Exchange (ETDEWEB)

    Silling, Stewart A.; Abe Askari (Boeing)

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the %22remaining life%22 of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  10. Catalytic Pyrolysis of Wild Reed over a Zeolite-Based Waste Catalyst

    OpenAIRE

    Myung Lang Yoo; Yong Ho Park; Young-Kwon Park; Sung Hoon Park

    2016-01-01

    Fast catalytic pyrolysis of wild reed was carried out at 500 °C. Waste fluidized catalytic cracking (FCC) catalyst disposed from a petroleum refinery process was activated through acetone-washing and calcination and used as catalyst for pyrolysis. In order to evaluate the catalytic activity of waste FCC catalyst, commercial HY zeolite catalyst with a SiO2/Al2O3 ratio of 5.1 was also used. The bio-oil produced from pyrolysis was analyzed using gas chromatography/mass spectrometry (GC/MS). When...

  11. 21 CFR 137.190 - Cracked wheat.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cracked wheat. 137.190 Section 137.190 Food and... Related Products § 137.190 Cracked wheat. Cracked wheat is the food prepared by so cracking or cutting into angular fragments cleaned wheat other than durum wheat and red durum wheat that, when tested...

  12. Effect of crack opening on UT response

    Energy Technology Data Exchange (ETDEWEB)

    Virkkunen, I.; Kemppainen, M. [Trueflaw OY, Espoo (Finland); Pitkaenen, J. [Posiva, Olkiluoto (Finland)

    2006-07-01

    Crack opening is one of the key parameters affecting the UT response of the crack. Tight cracks with small opening tend to be more difficult to detect and characterize than cracks that have wider opening. In particular, the opening of crack tip has marked effect on the crack tip diffraction signal often used for crack sizing. Service-induced cracks found exhibit wide variety of different openings. The opening is affected by the service loads and crack growth mechanism. In general, cracks grown by high loads tend to have wider opening than cracks produced by small loads. Furthermore, residual stresses may alter the opening. In order to simulate the wide variety of openings of the service-induced cracks, a novel method for producing artificial flaws with controlled opening is presented. A set of similar realistic flaws was produced by controlled thermal fatigue loading. The as-produced ''baseline'' UT response of these cracks was recorded with phased array technique using shear waves. Some of the flaws were then subjected to different loading sequences to manipulate their opening. The UT response of the modified cracks was then recorded and compared to that of the baseline response. The crack tip signals were measured also with longitudinal waves before cutting the specimen. Finally, the sample was carefully sectioned to reveal the opening of the produced flaws and the effect of crack opening to the UT response is analyzed. (orig.)

  13. Fiber Sensing of Micro -Crack

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Optical fiber sensors are used for sensing micro-cracking in composite and metal materials in aerospace applications. The sensing mechanism is based on the detection of acoustic emission signals, which are known to emanate from micro-cracks when they grow under further loading. The sensor head consists of a fiber Bragg grating that is capable of detecting acoustic emission signals generated by pencil lead breaking, of frequencies up to 200 kHz.

  14. Fiber Sensing of Micro -Crack

    Institute of Scientific and Technical Information of China (English)

    Hong-Liang Cui

    2003-01-01

    Optical fiber sensors are used for sensing micro -cracking in composite and metal materials in aerospace applications.The sensing mechanism is based on the detection of acoustic emission signals, which are known to emanate from micro-cracks when they grow under further loading. The sensor head consists of a fiber Bragg grating that is capable of detecting acoustic emission signals generated by pencil lead breaking, of frequencies up to 200 kHz.

  15. Synthesis of cracked Calophyllum inophyllum oil using fly ash catalyst for diesel engine application

    KAUST Repository

    Muthukumaran, N.

    2015-04-16

    In this study, production of hydrocarbon fuel from Calophyllum inophyllum oil has been characterized for diesel engine application, by appraising essential fuel processing parameters. As opposed to traditional trans-esterification process, the reported oil was cracked using a catalyst, as the latter improves the fuel properties better than the former. In a bid to make the production process economically viable, a waste and cheap catalyst, RFA (raw fly ash), has been capitalized for the cracking process as against the conventional zeolite catalyst. The fuel production process, which is performed in a fixed bed catalytic reactor, was done methodologically after comprehensively studying the characteristics of fly ash catalyst. Significantly, fly ash characterization was realized using SEM and EDS, which demarcated the surface and internal structures of fly ash particles before and after cracking. After the production of hydrocarbon fuel from C. inophyllum oil, the performed compositional analysis in GC-MS revealed the presence of esters, parfins and olefins. Followed by the characterization of catalytically cracked C. inophyllum oil, suitable blends of it with diesel were tested in a single cylinder diesel engine. From the engine experimental results, BTE (brake thermal efficiency) of the engine for B25 (25% cracked C. inophyllum oil and 75% diesel) was observed to be closer to diesel, while it decreased for higher blends. On the other hand, emissions such as HC (hydrocarbon), CO (carbon monoxide) and smoke were found to be comparable for B25 with diesel. © 2015 Elsevier Ltd. All rights reserved.

  16. Formation and interpretation of dilatant echelon cracks.

    Science.gov (United States)

    Pollard, D.D.; Segall, P.; Delaney, P.T.

    1982-01-01

    The relative displacements of the walls of many veins, joints, and dikes demonstrate that these structures are dilatant cracks. We infer that dilatant cracks propagate in a principal stress plane, normal to the maximum tensile or least compressive stress. Arrays of echelon crack segments appear to emerge from the peripheries of some dilatant cracks. Breakdown of a parent crack into an echelon array may be initiated by a spatial or temporal rotation of the remote principal stresses about an axis parallel to the crack propagation direction. Near the parent-crack tip, a rotation of the local principal stresses is induced in the same sense, but not necessarily through the same angle. Incipient echelon cracks form at the parent-crack tip normal to the local maximum tensile stress. Further longitudinal growth along surfaces that twist about axes parallel to the propagation direction realigns each echelon crack into a remote principal stress plane. The walls of these twisted cracks may be idealized as helicoidal surfaces. An array of helicoidal cracks sweeps out less surface area than one parent crack twisting through the same angle. Thus, many echelon cracks grow from a single parent because the work done in creating the array, as measured by its surface area decreases as the number of cracks increases. -from Authors

  17. Effects of different level addition of zeolite ZSM-5 additive on quality and composition of the dry gas, LPG (Liquefied Petroleum Gas) and gasoline, produced in FCC (Fluid Catalytic Cracking); Efeito dos diferentes niveis de adicao de aditivos de ZSM-5 na qualidade e composicao do gas combustivel, GLP e gasolina produzidos em FCC

    Energy Technology Data Exchange (ETDEWEB)

    Bastiani, Raquel; Pimenta, Ricardo D.M.; Almeida, Marlon B.B.; Lau, Lam Y. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The effects of the addition of different level of ZSM-5 additives on different FCC catalysts formulations have been studied on laboratory scale FST (Fluidized Simulation Test). The main objective of the present work is to perform a qualitative identification of the main parameters of FCC catalyst which affect the ZSM-5 additives performance concerning quality and composition of Dry Gas, LPG and Gasoline. The product composition of each test was analyzed by PIANO groups separated by carbon number. The effect of ZSM-5 on products composition was evaluated. The results showed that the ZSM-5 additive cracks gasoline range olefins and isoparaffins into Dry Gas and LPG, favoring the formation of ethylene, propylene and butylenes, while the absolute yield of gasoline aromatics changes little. The aromatics fraction in gasoline, MON and RON numbers in gasoline increase. The ZSM-5 effectiveness is negatively affected by high levels of rare earth on FCC catalyst (RE-USY). Higher hydrogen transfer provides lower olefins (higher than C6) formation, which are the most reactive species for ZSM-5 cracking. (author)

  18. Catalytic coherence transformations

    Science.gov (United States)

    Bu, Kaifeng; Singh, Uttam; Wu, Junde

    2016-04-01

    Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.

  19. Elastic-plastic analytical solution for centric crack loaded by two pairs of point shear forces in finite plate

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-ping; LING Tong-hua

    2006-01-01

    The near crack line analysis method was used to investigate a centric crack loaded by two pairs of point shear forces in a finite plate, and the analytical solution was obtained. The solution includes the unit normal vector of the elastic-plastic boundary near the crack line, the elastic-plastic stress fields near the crack line, the variations of the length of the plastic zone along the crack line with an external load, and the bearing capacity of a finite plate with a centric crack loaded by two pairs of point shear forces. The results are sufficiently precise near the crack line because the assumptions of small scale yielding theory have not been made and no other assumptions are taken.

  20. Fatigue reliability of cracked engineering structures

    Science.gov (United States)

    Lanning, David Bruce, Jr.

    1997-12-01

    This study investigates the reliability of engineering structures containing fatigue cracks. Stress concentrations and welded joints are probable locations for the initiation and propagation of fatigue cracks. Due to the many unknowns of loading, materials properties, crack sizes and crack shapes present at these locations, a statistics-based reliability analysis is valuable in the careful consideration of these many different random factors involved in a fatigue life analysis, several of which are expanded upon in this study. The basic problem of a crack near a stress concentration is first considered. A formulation for the aspect ratio (a/c) of a propagating semi-elliptical fatigue crack located at the toe of a welded T-joint is developed using Newman and Raju's stress intensity factor for a cracked flat plate with a weld magnification factor and compared to that of a cracked flat plate, and the reliability in terms of fatigue lifetime is calculated with the aid of Paris' crack propagation equation for membrane and bending loadings. Crack closure effects are then introduced in the consideration of short crack effects, where crack growth rates typically may exceed those found using traditional linear elastic fracture mechanics solutions for long cracks. The probability of a very small, microstructurally influenced crack growing to a size influenced by local plastic conditions is calculated utilizing the probability of a crack continuing to grow past an obstacle, such as a grain boundary. The result is then combined with the probability for failure defined using the crack closure-modified Paris equation to find an overall reliability for the structure. Last, the probability of fracture is determined when a crack front encounters regions of non-uniform toughness, such as typical in the heat affected zone of a welded joint. An expression for the effective crack lengths of the dissimilar regions is derived, and used in a weakest-link fracture model in the evaluation

  1. Pore Structure and Catalytic Performance of Steam-Dealuminated ZSM-5/Y Composite Zeolites

    Institute of Scientific and Technical Information of China (English)

    GuoJintao; ShenBaojian; ChenHonglin

    2005-01-01

    For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET(Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke.

  2. Simulation of Chloride Diffusion in Cracked Concrete with Different Crack Patterns

    OpenAIRE

    Xiao-Yong Wang; Li-Na Zhang

    2016-01-01

    Chloride-induced corrosion of steel rebar is one of the primary durability problems for reinforced concrete structures in marine environment. Furthermore, if the surfaces of concrete structures have cracks, additional chloride can penetrate into concrete through cracked zone. For chloride ingression into cracked concrete, former researches mainly focus on influence of crack width on chloride diffusion coefficients. Other crack characteristics, such as chloride depth, crack shape (equal-width ...

  3. The role of grain boundary structure and crystal orientation on crack growth asymmetry in aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Adlakha, I. [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287 (United States); Tschopp, M.A. [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Solanki, K.N., E-mail: kiran.solanki@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287 (United States)

    2014-11-17

    Atomistic simulations have shown that the grain boundary (GB) structure affects a number of physical, mechanical, thermal, and chemical properties, which can have a profound effect on macroscopic properties of polycrystalline materials. The research objective herein is to use atomistic simulations to explore the role that GB structure and the adjacent crystallographic orientations have on the directional asymmetry of an intergranular crack (i.e. cleavage behavior is favored along one direction, while ductile behavior along the other direction of the interface) for aluminum grain boundaries. Simulation results from seven 〈110〉 symmetric tilt grain boundaries (STGBs) show that the GB structure and the associated free volume directly influence the stress–strain response, crack growth rate, and crack tip plasticity mechanisms for middle-tension (M(T)) crack propagation specimens. In particular, the structural units present within the GB promote whether a dislocation or twinning-based mechanism operates at the crack tip during intergranular fracture along certain GBs (e.g., the ‘E’ structural unit promotes twinning at the crack tip in Al). Furthermore, the crystallography of the adjacent grains, and therefore the available slip planes, can significantly affect the crack growth rates in both directions of the crack – this creates a strong directional asymmetry in the crack growth rate in the Σ11 (113) and the Σ27 (552) STGBs. Upon comparing these results with the theoretical Rice criterion, it was found that certain GBs in this study (Σ9 (221), Σ11 (332) and Σ33 (441)) show an absence of directional asymmetry in the observed crack growth behavior, in conflict with the Rice criterion. The significance of the present research is that it provides a physical basis for the role of GB character and crystallographic orientation on intergranular crack tip deformation behavior.

  4. Crack propagation in prestressed plates

    Energy Technology Data Exchange (ETDEWEB)

    Farshad, M.; Flueler, P. [EMPA, Duebendorf (Switzerland)

    1995-12-31

    A second-order theory of initially stressed plates in the plane stress mode was used to find the dynamic stress field in the vicinity of a crack tip. Rapid crack propagation (RCP) behaviour associated with stresses caused by internal pressure and temperature was examined. The flat plate was placed under thermal conditions and was prestressed in such a way as to simulate hoop stress that may be expected in a pipe made of the same material. The presence of the tensile prestress in the thin plate raised the levels of the principal stress values and affected the direction at which the maxima of principal stress occurred. Second-order effects played an important role in the vicinity of the crack tip. Increased crack speed caused increased stress levels. There existed a limiting value at which the stresses at the crack tip became unbounded. The limiting value was affected by prestressing. The concept of simulating RCP testing of polymer pipes by a test on a conditioned plate of the same material, prestressed to simulate hoop stress caused by internal pressure, was judged to be reasonable. 6 refs. 5 figs.

  5. SHORT FATIGUE CRACK PARAMETER BASED ON THE TOTAL CRACK AREA

    Institute of Scientific and Technical Information of China (English)

    Z.X.Wu; X.C.Wu

    2001-01-01

    The progressive fatigue damage of a material is closely related to the whole populationof cracks on the surface of an un-notched specimen.In order to understand whichparameter is a more useful indicator of fatigue damage,rotatory bending fatigue testswere carried out using smooth specimens of medium-carbon steel.The behavior ofshort crack propagation during fatigue was examined and a new parameter "totalcrack area" was suggested.The aim of this paper is to extend the research on fatiguedamage in the already studied steel and to study how these damage parameters arecorrelated with the process of fatigue damage in order to evaluate the effectiveness ofdamage detection methods.

  6. Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.Y.

    1997-01-01

    The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243{degrees}C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling.

  7. Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results

    International Nuclear Information System (INIS)

    The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243 degrees C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling

  8. Production of hydrogen by thermocatalytic cracking of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, N.Z. [Univ. of Central Florida, Cape Canaveral, FL (United States)

    1995-09-01

    It is universally accepted that in the next few decades hydrogen production will continue to rely on fossil fuels (primarily, natural gas). On the other hand, the conventional methods of hydrogen production from natural gas (for example, steam reforming) are complex multi-step processes. These processes also result in the emission of large quantities of CO{sub 2} into the atmosphere that produce adverse ecological effects. One alternative is the one-step thermocatalytic cracking (TCC) (or decomposition) of natural gas into hydrogen and carbon. Preliminary analysis indicates that the cost of hydrogen produced by thermal decomposition of natural gas is somewhat lower than the conventional processes after by-product carbon credit is taken. In the short term, this process can be used for on-site production of hydrogen-methane mixtures in gas-filling stations and for CO{sub x}-free production of hydrogen for fuel cell driven prime movers. The experimental data on the thermocatalytic cracking of methane over various catalysts and supports in a wide range of temperatures (500-900{degrees}C) are presented in this paper. Two types of reactors were designed and built at FSEC: continuous flow and pulse fix bed catalytic reactors. The temperature dependence of the hydrogen production yield using oxide type catalysts was studied. Alumina-supported Ni- and Fe-catalysts demonstrated relatively high efficiency in the methane cracking reaction at moderate temperatures (600-800{degrees}C). Kinetic curves of hydrogen production over metal and metal oxide catalysts at different temperatures are presented in the paper. Fe-catalyst demonstrated good stability (for several hours), whereas alumina-supported Pt-catalyst rapidly lost its catalytic activity.

  9. Simulation of Chloride Diffusion in Cracked Concrete with Different Crack Patterns

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2016-01-01

    Full Text Available Chloride-induced corrosion of steel rebar is one of the primary durability problems for reinforced concrete structures in marine environment. Furthermore, if the surfaces of concrete structures have cracks, additional chloride can penetrate into concrete through cracked zone. For chloride ingression into cracked concrete, former researches mainly focus on influence of crack width on chloride diffusion coefficients. Other crack characteristics, such as chloride depth, crack shape (equal-width crack or tapered crack, crack density, and spacing, are not studied in detail. To fill this gap, this paper presents a numerical procedure to simulate chloride ingression into cracked concrete with different crack geometry characteristics. Cracked concrete is divided into two parts, sound zone and cracked zone. For stress-free concrete, the diffusion coefficient of sound zone is approximately assumed to be the same as sound concrete, and the diffusion coefficient of cracked zone is expressed as a piecewise function of crack width. Two-dimensional finite element method is used to determine chloride concentration. It is found that, with the increasing of crack width, crack depth, and crack amount, chloride ingression will aggravate. The analysis results generally agree with experimental results.

  10. IDENTIFICATION OF CRACKED ROTOR BY WAVELET TRANSFORM

    Institute of Scientific and Technical Information of China (English)

    邹剑; 陈进; 蒲亚鹏

    2002-01-01

    The dynamic equation of cracked rotor in rotational frame was modelled, the numerical simulation solutions of the cracked rotor and the uncracked rotor were obtained. By the wavelet transform, the time-frequency properties of the cracked rotor and the uncracked rotor were discussed, the difference of the time-frequency properties between the cracked rotor and the uncracked rotor was compared. A new detection algorithm using wavelet transform to identify crack was proposed. The experiments verify the availability and validity of the wavelet transform in identification of crack.

  11. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    This thesis describes the catalytic conversion of bioethanol into higher value chemicals. The motivation has been the unavoidable coming depletion of the fossil resources. The thesis is focused on two ways of utilising ethanol; the steam reforming of ethanol to form hydrogen and the partial oxida...

  12. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

    The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.

  13. Catalytic efficiency of designed catalytic proteins.

    Science.gov (United States)

    Korendovych, Ivan V; DeGrado, William F

    2014-08-01

    The de novo design of catalysts that mimic the affinity and specificity of natural enzymes remains one of the Holy Grails of chemistry. Despite decades of concerted effort we are still unable to design catalysts as efficient as enzymes. Here we critically evaluate approaches to (re)design of novel catalytic function in proteins using two test cases: Kemp elimination and ester hydrolysis. We show that the degree of success thus far has been modest when the rate enhancements seen for the designed proteins are compared with the rate enhancements by small molecule catalysts in solvents with properties similar to the active site. Nevertheless, there are reasons for optimism: the design methods are ever improving and the resulting catalyst can be efficiently improved using directed evolution.

  14. Cracking and hydrocracking of triglycerides for renewable liquid fuels: alternative processes to transesterification

    Energy Technology Data Exchange (ETDEWEB)

    Frety, Roger; Rocha, Maria da Graca C. da; Brandao, Soraia T., E-mail: frety@unifacs.b [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica; Pontes, Luiz A.M; Padilha, Jose F. [Universidade de Salvador (UNIFACS), BA (Brazil); Borges, Luiz E.P.; Gonzalez, Wilma A. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

    2011-07-01

    The most used industrial processes for the production of liquid fuels like diesel type are based on the methanolysis and ethanolysis of various oil reactants, such as palm, soybean and rapeseed oils, in the presence of homogeneous base catalysts. However, thermal and catalytic transformations of vegetable oils using available reactors and industrial processes are possible alternatives and deserve attention. In fact, three industrial processes are operating and new projects are announced. The present work analyses the experimental studies performed up to now by Brazilian researchers in the field of cracking, catalytic cracking and hydrocracking of pure or modified vegetable oils. From the published results, some research areas for the near future are suggested. (author)

  15. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H. [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1998-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  16. Crack Tip Parameters for Growing Cracks in Linear Viscoelastic Materials

    DEFF Research Database (Denmark)

    Brincker, Rune

    In this paper the problem of describing the asymptotic fields around a slowly growing crack in a linearly viscoelastic material is considered. It is shown that for plane mixed mode problems the asymptotic fields must be described by 6 parameters: 2 stress intensity factors and 4 deformation...

  17. Crack growth resistance in nuclear graphites

    Science.gov (United States)

    Ouagne, Pierre; Neighbour, Gareth B.; McEnaney, Brian

    2002-05-01

    Crack growth resistance curves for the non-linear fracture parameters KR, JR and R were measured for unirradiated PGA and IM1-24 graphites that are used as moderators in British Magnox and AGR nuclear reactors respectively. All the curves show an initial rising part, followed by a plateau region where the measured parameter is independent of crack length. JR and R decreased at large crack lengths. The initial rising curves were attributed to development of crack bridges in the wake of the crack front, while, in the plateau region, the crack bridging zone and the frontal process zone, ahead of the crack tip, reached steady state values. The decreases at large crack lengths were attributed to interaction of the frontal zone with the specimen end face. Microscopical evidence for graphite fragments acting as crack bridges showed that they were much smaller than filler particles, indicating that the graphite fragments are broken down during crack propagation. There was also evidence for friction points in the crack wake zone and shear cracking of some larger fragments. Inspection of KR curves showed that crack bridging contributed ~0.4 MPa m0.5 to the fracture toughness of the graphites. An analysis of JR and R curves showed that the development of the crack bridging zone in the rising part of the curves contributed ~20% to the total work of fracture. Energies absorbed during development of crack bridges and steady state crack propagation were greater for PGA than for IM1-24 graphite. These differences reflect the greater extent of irreversible processes occurring during cracking in the coarser microtexture of PGA graphite.

  18. FRACTAL KINEMATICS OF CRACK PROPAGATION IN GEOMATERIALS

    Institute of Scientific and Technical Information of China (English)

    谢和平

    1995-01-01

    Experimental results indicate that propagation paths of cracks in geomaterials are often irregular, producing rough fracture surfaces which are fractal. A formula is derived for the fractal kinematics of crack propagation in geomaterials. The formula correlates the dynamic and static fracture toughnesses with crack velocity, crack length and a microstructural parameter, and allows the fractal dimension to be obtained. From the equations for estimating crack velocity and fractal dimension it can be shown that the measured crack velocity, Vo , should be much smaller than the fractal crack velocity, V. It can also be shown that the fractal dimension of the crack propagation path can be calculated directly from Vo and from the fracture toughness.

  19. China Cracks Down Internet Piracy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ National Copyright Administration of China carried out a special operation to crack down on behaviors involving network infringement and piracy from September to December in 2005 ,according to the speech of Yan Xiaohong,Deputy Commissioner of National Copyright Administration on the Press Conference of the State Council.Now the relevant conditions are as follows:

  20. China Cracks Down Internet Piracy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

      National Copyright Administration of China carried out a special operation to crack down on behaviors involving network infringement and piracy from September to December in 2005 ,according to the speech of Yan Xiaohong,Deputy Commissioner of National Copyright Administration on the Press Conference of the State Council.Now the relevant conditions are as follows:……

  1. HYDROTHERMAL CRACKING OF RESIDUAL OILS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The hydrothermal cracking of heavy oils, such as Canadian oil sand bitumen and Arabian heavy vacuum residue, as well as their model compound were performed over sulfided Ni/Al2O3 and NiMo/Al2O3 catalysts under 663~703 K and 6.0~8.0 MPa of hydrogen pressure in a batch autoclave reactor. According to the reaction mechanism of hydrothermal cracking, a small amount of free redical initiators, such as di-tert-peroxide, sulfur, etc., was added into the feed to generate free redicals at lower temperature, and obviously showed promotional effect on the conversion of hydrocarbons. The reaction mechanisms of hydrothermal cracking as well as the enhancing effect of initiators were studied by a probe reaction with 1-phenyldodecane as a model compound. The hydrothermal cracking of hydrocarbon proceeded via free redical mechanism and hydrogenating quench. The initiators might easily generate free redicals under reaction temperature, these redicals might abstract H from hydrocarbon molecule and reasonably initiate the chain reactions, therefore, promote the conversion of hydrocarbon even at lower reaction temperature.

  2. Study on Deactivation and Cracking Performance of Catalysts Containing Y and MFI Zeolites

    Institute of Scientific and Technical Information of China (English)

    Chen Zhenyu; Li Caiying; Tian Huiping; Huang Zhiqing

    2004-01-01

    This article investigated the deactivation caused by hydrothermal treatment and metal contamination of two cracking catalysts containing the Y and ZRP- 1 zeolites aimed at maximization of light olefin yield.Test results had shown that the hydrothermal stability and resistance to metal contamination of the ZRP-1zeolite were apparently better than those of the Y zeolite. Hydrothermal treatment and metal contamination had not only changed the catalytic cracking performance of respective zeolites, but at the same time had also modified to a definite degree of the relative proportions of effective components in these two zeolites and affected the synergistic effects between them, resulting in a relative enhancement of secondary cracking ability of the catalyst and increased olefin selectivity in the FCC products. In the course of application of catalyst for maximization of light olefins yield appropriate adjustment of the relative proportion of two active components can help to alleviate the products distribution and selectivity changes caused by deactivationof FCC catalysts.

  3. Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-11-19

    Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported. The USY catalyst (FCC-Y) was modified by steaming to form a significantly lower acidity catalyst (FCC-SY). The current study shows that the FCC-SY catalyst favors EB disproportionation more than cracking. A comparison has been made between the results of EB conversion over the lowly acidic catalyst (FCC-SY) and the highly acidic catalyst (FCC-Y) under identical conditions. It was observed that increase in catalyst acidity favored cracking of EB at the expense of disproportionation. Kinetic parameters for EB disappearance during disproportionation reaction over the FCC-SY catalyst were calculated using the catalyst activity decay function based on time on stream (TOS). © 2008 American Chemical Society.

  4. Rapid Deployment of Rich Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Richard S. Tuthill

    2004-06-10

    The overall objective of this research under the Turbines Program is the deployment of fuel flexible rich catalytic combustion technology into high-pressure ratio industrial gas turbines. The resulting combustion systems will provide fuel flexibility for gas turbines to burn coal derived synthesis gas or natural gas and achieve NO{sub x} emissions of 2 ppmvd or less (at 15 percent O{sub 2}), cost effectively. This advance will signify a major step towards environmentally friendly electric power generation and coal-based energy independence for the United States. Under Phase 1 of the Program, Pratt & Whitney (P&W) performed a system integration study of rich catalytic combustion in a small high-pressure ratio industrial gas turbine with a silo combustion system that is easily scalable to a larger multi-chamber gas turbine system. An implementation plan for this technology also was studied. The principal achievement of the Phase 1 effort was the sizing of the catalytic module in a manner which allowed a single reactor (rather than multiple reactors) to be used by the combustion system, a conclusion regarding the amount of air that should be allocated to the reaction zone to achieve low emissions, definition of a combustion staging strategy to achieve low emissions, and mechanical integration of a Ceramic Matrix Composite (CMC) combustor liner with the catalytic module.

  5. Wear crack characterization by photothermal radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, J.L. [GRSM/LEO, Faculte des Sciences, 51 - Reims (France); Egee, M. [GRSM/LEO, Faculte des Sciences, 51 - Reims (France)

    1996-08-01

    After demonstrating recently the possibilities of scanning photothermal radiometry for wear crack detection (Bodnar et al., J. Phys. IV, 4 (1994) 591-594), we now study its possibilities for dimensional characterization of these kinds of flaws. In this respect, we present here the results obtained from our study of two types of emerging cracks, i.e. thin and shallow cracks in samples with a reflecting surface as well as wider and deeper cracks in samples with an absorbing surface. (orig.)

  6. Fatigue crack growth from a cracked elastic particle into a ductile matrix

    NARCIS (Netherlands)

    Groh, S.; Olarnrithinun, S.; Curtin, W. A.; Needleman, A.; Deshpande, V. S.; Van der Giessen, E.

    2008-01-01

    The monotonic and cyclic crack growth rate of cracks is strongly influenced by the microstructure. Here, the growth of cracks emanating from pre-cracked micron-scale elastic particles and growing into single crystals is investigated, with a focus on the effects of (i) plastic confinement due to the

  7. Propagation and band width of smeared cracks

    NARCIS (Netherlands)

    Slobbe, A.T.

    2015-01-01

    The crack band approach (in the smeared crack concept) is widely used for the modeling of concrete fracture and is an important analysis technique within advanced engineering. However, the simulations can be impeded by mesh-induced directional bias. Cracks prefer to propagate along continuous mesh l

  8. An analytical thermal fatigue crack growth approach

    International Nuclear Information System (INIS)

    The paper presents recent works on the thermal fatigue crack growth approach in structure integrity analysis proposed by nuclear standard codes such as A16 Appendix of RCC-MR. The proposed approach for crack growth is used to study the mechanisms leading to cracking of piping as a result of thermal loading in mixed flow zones

  9. Assessment of cracking in dissimilar metal welds

    International Nuclear Information System (INIS)

    During the refueling in 2000, indications were observed by non-destructive testing at four locations in the reactor pressure vessel (RPV) nozzle to safe end weld in Ringhals 4. All indications were confined to the outlet nozzle (hotleg) oriented at 25 deg, a nozzle with documented repair welding. Six boat samples were removed from the four locations, and the samples were subsequently subjected to a metallographic examination. The objectives were to establish the fracture morphology, and if possible the root cause for cracking. The examination revealed that cracks were present at all four boat sample locations and that they all were confined to the weld metal, alloy 182. Cracking extended in the axial direction of the safe-end. There was no evidence of any cracks extending into the RPV-steel, or the stainless steel safe-end. All cracking was interdendritic and significantly branched. Among others, these observations strongly suggested crack propagation mainly was caused by interdendritic stress corrosion cracking. In addition, crack type defects and isolated areas on the fracture surfaces suggested the presence of hot cracking, which would have been formed during fabrication. The reason for crack initiation could not be established based on the boat samples examined. However, increased stress levels due to repair welding, cold work from grinding, and defects produced during fabrication, e. g. hot cracks, may alone or in combination have contributed to crack initiation

  10. Cracked Teeth: A Review of the Literature

    OpenAIRE

    Lubisich, Erinne B.; Hilton, Thomas J.; Ferracane, Jack

    2010-01-01

    Although cracked teeth are a common problem for patients and dentists, there is a dearth of evidence-based guidelines on how to prevent, diagnose, and treat cracks in teeth. The purpose of this article is to review the literature to establish what evidence exists regarding the risk factors for cracked teeth and their prevention, diagnosis, and treatment.

  11. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  12. Fatigue crack growth simulations of 3-D linear elastic cracks under thermal load by XFEM

    Institute of Scientific and Technical Information of China (English)

    Himanshu PATHAK[1; Akhilendra SINGH[2; I.V. SINGH[3; S. K. YADAV[3

    2015-01-01

    This paper deals with the fatigue crack growth simulations of three-dimensional linear elastic cracks by XFEM under cyclic thermal load. Both temperature and displacement approximations are extrinsically enriched by Heaviside and crack front enrichment functions. Crack growth is modelled by successive linear extensions, and the end points of these linear extensions are joined by cubic spline segments to obtain a modified crack front. Different crack geometries such as planer, non-planer and arbitrary spline shape cracks are simulated under thermal shock, adiabatic and isothermal loads to reveal the sturdiness and versatility of the XFEM approach.

  13. Monte Carlo simulation of micro crack propagation behavior for stress corrosion cracking

    International Nuclear Information System (INIS)

    A calculation code of Monte Carlo simulation for micro crack propagation behavior of stress corrosion cracking has been developed. Improvements for micro crack growth rate treatments and stress distributions have been made. Calculated crack depth distributions were compared with the CBB test results for sensitized stainless steels and low carbon stainless steels with hardened layer. For sensitized stainless steels, the calculated crack depth distribution could well reproduce the CBB test results by taking into account crack growth rates obtained from experiments. For low carbon stainless steels, although considering stress distributions improved the overestimation of crack depths, the calculated crack depth distribution could not well reproduce the CBB test result. The results revealed that the effects of the crack growth rate and the stress distribution on micro crack propagation behaviors. (author)

  14. Delayed hydride cracking: theoretical model testing to predict cracking velocity

    International Nuclear Information System (INIS)

    Pressure tubes from Candu nuclear reactors as any other component manufactured with Zr alloys are prone to delayed hydride cracking. That is why it is important to be able to predict the cracking velocity during the component lifetime from parameters easy to be measured, such as: hydrogen concentration, mechanical and microstructural properties. Two of the theoretical models reported in literature to calculate the DHC velocity were chosen and combined, and using the appropriate variables allowed a comparison with experimental results of samples from Zr-2.5 Nb tubes with different mechanical and structural properties. In addition, velocities measured by other authors in irradiated materials could be reproduced using the model described above. (author)

  15. Mesh sensitivity effects on fatigue crack growth by crack-tip blunting and re-sharpening

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2007-01-01

    Crack-tip blunting under tensile loads and re-sharpening of the crack-tip during unloading is one of the basic mechanisms for fatigue crack growth in ductile metals. Based on an elastic–perfectly plastic material model, crack growth computations have been continued up to 700 full cycles by using...... refinement is used to study the possibility of this type of behaviour within the present method. Even with much refined meshes no indication of crack surface folding is found here....

  16. Crack detection by stimulated infrared thermography

    Science.gov (United States)

    Bodnar, Jean-Luc

    2014-03-01

    In this paper, the potential of stimulated infrared thermography is studied for the detection of cracks located in metallic materials. To start with, the feasibility of the method is shown with the use of numerical simulations. Stimulated infrared thermography allows detecting emerging cracks in samples whether reflective or not as well as non-emerging cracks. In addition, crack detection is due to the radiative effects and/or the thermal effects induced by the defects. Then, the experimental device implemented for the study is detailed. Finally, experiments confirm that stimulated infrared thermography enables to detect microscopic cracks, whether emerging or non-emerging, in metal samples.

  17. NMR sensor for onboard ship detection of catalytic fines in marine fuel oils.

    Science.gov (United States)

    Sørensen, Morten K; Vinding, Mads S; Bakharev, Oleg N; Nesgaard, Tomas; Jensen, Ole; Nielsen, Niels Chr

    2014-08-01

    A mobile, low-field nuclear magnetic resonance (NMR) sensor for onboard, inline detection of catalytic fines in fuel oil in the shipping industry is presented as an alternative to onshore laboratory measurements. Catalytic fines (called cat fines) are aluminosilicate zeolite catalysts utilized in the oil cracking process at refineries. When present in fuel oil, cat fines cause abrasive wear of engine parts and may ultimately lead to engine breakdown with large economical consequences, thereby motivating methods for inline measurements. Here, we report on a robust, mobile, and low-cost (27)Al NMR sensor for continuous online measurement of the level of catalytic fines in fuel oil onboard ships. The sensor enables accurate measurements of aluminum (catalytic fines) in ppm concentrations in good agreement with commercial laboratory reference measurements. PMID:24988044

  18. NMR sensor for onboard ship detection of catalytic fines in marine fuel oils.

    Science.gov (United States)

    Sørensen, Morten K; Vinding, Mads S; Bakharev, Oleg N; Nesgaard, Tomas; Jensen, Ole; Nielsen, Niels Chr

    2014-08-01

    A mobile, low-field nuclear magnetic resonance (NMR) sensor for onboard, inline detection of catalytic fines in fuel oil in the shipping industry is presented as an alternative to onshore laboratory measurements. Catalytic fines (called cat fines) are aluminosilicate zeolite catalysts utilized in the oil cracking process at refineries. When present in fuel oil, cat fines cause abrasive wear of engine parts and may ultimately lead to engine breakdown with large economical consequences, thereby motivating methods for inline measurements. Here, we report on a robust, mobile, and low-cost (27)Al NMR sensor for continuous online measurement of the level of catalytic fines in fuel oil onboard ships. The sensor enables accurate measurements of aluminum (catalytic fines) in ppm concentrations in good agreement with commercial laboratory reference measurements.

  19. Catalytic destruction of tar in biomass derived producer gas

    International Nuclear Information System (INIS)

    The purpose of this study is to investigate catalytic destruction of tar formed during gasification of biomass, with the goal of improving the quality of the producer gas. This work focuses on nickel based catalysts treated with alkali in an effort to promote steam gasification of the coke that deposits on catalyst surfaces. A tar conversion system consisting of a guard bed and catalytic reactor was designed to treat the producer gas from an air blown, fluidized bed biomass gasifier. The guard bed used dolomite to crack the heavy tars. The catalytic reactor was used to evaluate three commercial steam reforming catalysts. These were the ICI46-1 catalyst from Imperial Chemical Industry and Z409 and RZ409 catalysts from Qilu Petrochemical Corp. in China. A 0.5-3 l/min slipstream from a 5 tpd biomass gasifier was used to test the tar conversion system. Gas and tar were sampled before and after the tar conversion system to evaluate the effectiveness of the system. Changes in gas composition as functions of catalytic bed temperature, space velocity and steam/TOC (total organic carbon) ratio are presented. Structural changes in the catalysts during the tests are also described

  20. Cracking of an Aircraft Wheel Rim Made From Al-Alloy 2014-T6

    OpenAIRE

    G. Kosec; Kovačič, G.; J. Hodolič; Kosec, B.

    2010-01-01

    Generally failures of different aircraft components and parts are revealed and examined by the use of non-destructive examination methods. In further detailed explanation and interpretation of failures optical and scanning electron microscopy are used. This paper deals with a problem of a crack on aircraft wheel rim made from aluminium alloy 2014-T6.The crack was observed during regular control by the maintenance unit for non-destructive examination of the Slovenian air carrier Adria Airways....

  1. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    damage factor is highest. Subsequently the stress history is imposed as boundary conditions in a periodic unit cell model, where an alumina inclusion is embedded in a AISI 52100 matrix. Cracks are assumed to grow radially from the inclusion under cyclic loading. The growth is predicted by means of...... irreversible fatigue cohesive elements. Different orientations of the cracks and different matrix-inclusion bonding conditions are analyzed and compared....

  2. MCFC-based marine APU: Comparison between conventional ATR and cracking coupled with SR integrated inside the stack pressurized vessel

    Energy Technology Data Exchange (ETDEWEB)

    Bensaid, S.; Specchia, S.; Saracco, G.; Specchia, V. [Materials Science and Chemical Engineering Department, Politecnico di Torino, Corso Duca degli Abruzzi, 24 - 10129 Torino (Italy); Federici, F. [Ansaldo Fuel Cells S.p.A., Corso Perrone 25, 16152 Genova (Italy)

    2009-02-15

    In the present work the implementation of MCFCs as auxiliary power units on-board large vessels, such as cruising, passengers or commercial, ships was investigated. The MCFC stack was designed to supply 500 kW{sub e} and was fed with diesel oil undergoing a reforming process. The system modelling of the plant was performed in steady-state and aimed at assessing the power efficiency for different reforming strategies, process configurations and constituting items thermal integrations. The code Matlab/Simulink was used to this end. Two major fuel processing strategies were examined: ''auto-thermal reforming'' and ''inside vessel steam reforming''. The latter consisted of a pre-reforming unit in which the liquid fuel underwent a catalytic cracking in mild conditions; subsequently, the resulting gas mixture made of light hydrocarbons was mixed with steam and fed into a steam reformer inside the MCFC stack vessel, where conversion to syngas occurred. Due to the high temperature (650 C) exothermic level of MCFC, the stack was compatible with a syngas steam reforming production thermally self sustained. This allowed to increase the global electrical efficiency from 32.7% (for the ATR-based system) up to 44.6%. The process was then designed aiming at increasing the overall efficiency by thermally integrating the outlet flue gases with the pre-heating section. This lead to efficiencies equal to 39.1% and 50.6% for the ''auto-thermal reforming'' and ''inside vessel steam reforming'', respectively. Finally, the process was upgraded from an auxiliary power unit (APU) to a combined heat and power unit (CHP), since the residual heat in the flue gases was recovered for heating purposes (sanitary water production) and the demineralised water recirculation was implemented to reduce the water make-up and the process environmental footprint. (author)

  3. Primary water stress corrosion cracking of alloy 600

    International Nuclear Information System (INIS)

    As United States nuclear reactors have aged, a number of problems have arisen. Among these are primary water cracking (PWSCC) of Alloy 600 in PWRs. Since 1989, when PWSCC was identified to the Nuclear Regulatory Commission (NRC) as an emerging issue, it has been reported in several components, including control rod drive mechanism (CRDM) penetrations. To address PWSCC of CRDM penetrations at U.S. plants, the industry developed a comprehensive inspection, evaluation, repair and mitigation program. Recent pilot inspections that revealed cracking at two of the three U.S. plants inspected indicate the problem is generic. Further, results of stress analyses indicate that an area of high stress exists that could cause cracking that would follow the J-groove weld. Such cracking was identified in a foreign reactor that had a resin intrusion. PWSCC of CRDMs remains an open issue. Proactive NRC/Industry programs for inspection and repair or replacement of affected components are essential for continued operation of nuclear reactors and for license extensions. (author)

  4. Fatigue cracks in Eurofer 97 steel: Part II. Comparison of small and long fatigue crack growth

    Science.gov (United States)

    Kruml, T.; Hutař, P.; Náhlík, L.; Seitl, S.; Polák, J.

    2011-05-01

    The fatigue crack growth rate in the Eurofer 97 steel at room temperature was measured by two different methodologies. Small crack growth data were obtained using cylindrical specimens with a shallow notch and no artificial crack starters. The growth of semicircular cracks of length between 10-2000 μm was followed in symmetrical cycling with constant strain amplitude ( R ɛ = -1). Long crack data were measured using standard CT specimen and ASTM methodology, i.e. R = 0.1. The growth of cracks having the length in the range of 10-30 mm was measured. It is shown that the crack growth rates of both types of cracks are in a very good agreement if J-integral representation is used and usual assumptions of the crack closure effects are taken into account.

  5. Fatigue cracks in Eurofer 97 steel: Part II. Comparison of small and long fatigue crack growth

    Energy Technology Data Exchange (ETDEWEB)

    Kruml, T., E-mail: kruml@ipm.cz [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, CZ 61662 Brno (Czech Republic); Hutar, P.; Nahlik, L.; Seitl, S.; Polak, J. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, CZ 61662 Brno (Czech Republic)

    2011-05-01

    The fatigue crack growth rate in the Eurofer 97 steel at room temperature was measured by two different methodologies. Small crack growth data were obtained using cylindrical specimens with a shallow notch and no artificial crack starters. The growth of semicircular cracks of length between 10-2000 {mu}m was followed in symmetrical cycling with constant strain amplitude (R{sub {epsilon}} = -1). Long crack data were measured using standard CT specimen and ASTM methodology, i.e. R = 0.1. The growth of cracks having the length in the range of 10-30 mm was measured. It is shown that the crack growth rates of both types of cracks are in a very good agreement if J-integral representation is used and usual assumptions of the crack closure effects are taken into account.

  6. Catalytic hydrogenation reactors for the fine chemicals industries. Their design and operation.

    OpenAIRE

    Westerterp, K.R.; Molga, E.J.; Gelder, van, M.

    1997-01-01

    The design and operation of reactors for catalytic, hydrogenation in the fine chemical industries are discussed. The requirements for a good multiproduct catalytic hydrogenation unit as well as the choice of the reactor type are considered. Packed bed bubble column reactors operated without hydrogen recycle are recommended as the best choice to obtain a flexible reactor with good selectivities. The results of an experimental study of the catalytic hydrogenation of 2,4-dinitrotoluene in a mini...

  7. Crack propagation in fracture mechanical graded structures

    Directory of Open Access Journals (Sweden)

    B. Schramm

    2015-10-01

    Full Text Available The focus of manufacturing is more and more on innovative and application-oriented products considering lightweight construction. Hence, especially functional graded materials come to the fore. Due to the application-matched functional material gradation different local demands such as absorbability, abrasion and fatigue of structures are met. However, the material gradation can also have a remarkable influence on the crack propagation behavior. Therefore, this paper examines how the crack propagation behavior changes when a crack grows through regions which are characterized by different fracture mechanical material properties (e.g. different threshold values KI,th, different fracture toughness KIC. In particular, the emphasis of this paper is on the beginning of stable crack propagation, the crack velocity, the crack propagation direction as well as on the occurrence of unstable crack growth under static as well as cyclic loading. In this context, the developed TSSR-concept is presented which allows the prediction of crack propagation in fracture mechanical graded structures considering the loading situation (Mode I, Mode II and plane Mixed Mode and the material gradation. In addition, results of experimental investigations for a mode I loading situation and numerical simulations of crack growth in such graded structures confirm the theoretical findings and clarify the influence of the material gradation on the crack propagation behavior.

  8. Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingzhi; Wei, Wei; Manke, Jeff; Vazquez, Arturo; Thompson, Jeff; Thompson, Mark

    2011-05-28

    Biomass gasification is a flexible and efficient way of utilizing widely available domestic renewable resources. Syngas from biomass has the potential for biofuels production, which will enhance energy security and environmental benefits. Additionally, with the successful development of low Btu fuel engines (e.g. GE Jenbacher engines), syngas from biomass can be efficiently used for power/heat co-generation. However, biomass gasification has not been widely commercialized because of a number of technical/economic issues related to gasifier design and syngas cleanup. Biomass gasification, due to its scale limitation, cannot afford to use pure oxygen as the gasification agent that used in coal gasification. Because, it uses air instead of oxygen, the biomass gasification temperature is much lower than well-understood coal gasification. The low temperature leads to a lot of tar formation and the tar can gum up the downstream equipment. Thus, the biomass gasification tar removal is a critical technology challenge for all types of biomass gasifiers. This USDA/DOE funded program (award number: DE-FG36-O8GO18085) aims to develop an advanced catalytic tar conversion system that can economically and efficiently convert tar into useful light gases (such as syngas) for downstream fuel synthesis or power generation. This program has been executed by GE Global Research in Irvine, CA, in collaboration with Professor Lanny Schmidt's group at the University of Minnesota (UoMn). Biomass gasification produces a raw syngas stream containing H2, CO, CO2, H2O, CH4 and other hydrocarbons, tars, char, and ash. Tars are defined as organic compounds that are condensable at room temperature and are assumed to be largely aromatic. Downstream units in biomass gasification such as gas engine, turbine or fuel synthesis reactors require stringent control in syngas quality, especially tar content to avoid plugging (gum) of downstream equipment. Tar- and ash-free syngas streams are a critical

  9. On-line catalytic upgrading of biomass fast pyrolysis products

    Institute of Scientific and Technical Information of China (English)

    LU Qiang; ZHU XiFeng; LI WenZhi; ZHANG Ying; CHEN DengYu

    2009-01-01

    Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of biomass and on-line analysis of the pyrolysis vapors. Four biomass materials (poplar wood, fir wood, cotton straw and rice husk) were pyrolyzed to reveal the difference among their products. Moreover, catalytic cracking of the pyrolysis vapors from cotton straw was performed by using five catalysts, including two microporous zeolites (HZSM-5 and HY) and three mesoporous catalysts (ZrO2&TiO2, SBA-15 and AI/SBA-15). The results showed that the distribution of the pyrolytic products from the four materials differed a little from each other, while catalytic cracking could significantly alter the pyrolytic products. Those important primary pyrolytic products such as levoglucosen, hydroxyacetaldehyde and 1-hydroxy-2-propanone were decreased greatly after catalysis. The two microporous zeolites were ef-fective to generate high yields of hydrocarbons, while the three mesoporous materials favored the formation of furan, furfural and other furan compounds, as well as acetic acid.

  10. Controlling fatigue crack paths for crack surface marking and growth investigations

    Directory of Open Access Journals (Sweden)

    S. Barter

    2016-01-01

    Full Text Available While it is well known that fatigue crack growth in metals that display confined slip, such as high strength aluminium alloys, develop crack paths that are responsive to the loading direction and the local microstructural orientation, it is less well known that such paths are also responsive to the loading history. In these materials, certain loading sequences can produce highly directional slip bands ahead of the crack tip and by adjusting the sequence of loads, distinct fracture surface features or progression marks, even at very small crack depths can result. Investigating the path a crack selects in fatigue testing when particular combinations of constant and variable amplitude load sequences are applied is providing insight into crack growth. Further, it is possible to design load sequences that allow very small amounts of crack growth to be measured, at very small crack sizes, well below the conventional crack growth threshold in the aluminium alloy discussed here. This paper reports on observations of the crack path phenomenon and a novel test loading method for measuring crack growth rates for very small crack depths in aluminium alloy 7050-T7451 (an important aircraft primary structural material. The aim of this work was to firstly generate short- crack constant amplitude growth data and secondly, through the careful manipulation of the applied loading, to achieve a greater understanding of the mechanisms of fatigue crack growth in the material being investigated. A particular focus of this work is the identification of the possible sources of crack growth retardation and closure in these small cracks. Interpreting these results suggests a possible mechanism for why small fatigue crack growth through this material under variable amplitude loading is faster than predicted from models based on constant amplitude data alone.

  11. Causes of death among crack cocaine users Causa mortis em usuários de crack

    Directory of Open Access Journals (Sweden)

    Marcelo Ribeiro

    2006-09-01

    Full Text Available OBJECTIVE: The study accompanied 131 crack-cocaine users over a 5-year period, and examined mortality patterns, as well as the causes of death among them. METHOD: All patients admitted to a detoxification unit in Sao Paulo between 1992 and 1994 were interviewed during two follow-up periods: 1995-1996 and 1998-1999. RESULTS: After 5 years, 124 patients were localized (95%. By the study endpoint (1999, 23 patients (17.6% had died. Homicide was the most prevalent cause of death (n = 13. Almost one third of the deaths were due to the HIV infection, especially among those with a history of intravenous drug use. Less than 10% died from overdose. CONCLUSIONS: The study suggests that the mortality risk among crack cocaine users is greater than that seen in the general population, being homicide and AIDS the most common causes of death among such individuals.OBJETIVO: O estudo acompanhou, por cinco anos, um grupo de 131 usuários de crack e observou os padrões de mortalidade, bem como as causas mortis entre esses. MÉTODO: Todos os pacientes que se internaram em um serviço de desintoxicação, localizado no município de São Paulo, entre 1992-1994 foram entrevistados em duas ocasiões: 1995-1996 e 1998-1999. RESULTADOS: Após cinco anos, 124 pacientes foram localizados (95%. Vinte e três pacientes (17,6% haviam morrido ao final do quinto ano de seguimento, sendo os homicídios a causa mortis mais prevalente (n = 13. Quase um terço dos pacientes morreu devido à infecção pelo vírus da imunodeficiência adquirida (HIV, especialmente aqueles com antecedentes pessoais de uso de drogas endovenosas. Menos de 10% dos pacientes morreu de overdose. CONCLUSÕES: O estudo sugere que os usuários de crack têm maior risco de morte do que a população geral, sendo os homicídios e a AIDS as causas mais observadas.

  12. Online Bridge Crack Monitoring with Smart Film

    Directory of Open Access Journals (Sweden)

    Benniu Zhang

    2013-01-01

    Full Text Available Smart film crack monitoring method, which can be used for detecting initiation, length, width, shape, location, and propagation of cracks on real bridges, is proposed. Firstly, the fabrication of the smart film is developed. Then the feasibility of the method is analyzed and verified by the mechanical sensing character of the smart film under the two conditions of normal strain and crack initiation. Meanwhile, the coupling interference between parallel enameled wires of the smart film is discussed, and then low-frequency detecting signal and the custom communication protocol are used to decrease interference. On this basis, crack monitoring system with smart film is designed, where the collected crack data is sent to the remote monitoring center and the cracks are simulated and recurred. Finally, the monitoring system is applied to six bridges, and the effects are discussed.

  13. Numerical Study of Corrosion Crack Opening

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Frandsen, Henrik Lund; Svensson, Staffan

    2008-01-01

    for the corrosion crack opening. Experiments and theoretical analysis by a numerical method, FEM, support that the relation between the reduction of the reinforcement bar diameter due to corrosion and the corresponding increase in crack width for a given time interval, measured on the surface of a concrete specimen...... is proportional. More recently, the constant of proportionality, the so-called crack-corrosion index, has been studied further with respect to its dependence on the diameter of the reinforcement and the concrete cover. In the present paper the above-mentioned work is presented and extended with more realistic 3D......-models of the cracked concrete beam. The crack-corrosion index is evaluated for a variation of different parameters, i.e. bar diameter, concrete cover, crack length and type of corrosion product. This paper is an extended version of a paper by Thoft-Christensen et al. (2005) presented at the IFIP WG 7.5 Conference...

  14. Fluid structural response of axially cracked cylinders

    International Nuclear Information System (INIS)

    The fluid structural (FS) response of a cylindrical pressure vessel to a suddenly occurring longitudinal through-wall crack is predicted. The effects of vessel internals and depressurization of the compressed water on dynamic crack opening displacements are investigated. A three dimensional (3D) structural finite element model is used as a basis for the development of a two dimensional (2D) FS model. A slice of the vessel taken at the crack midspan and normal to the cylinder axis is modeled. Crack opening displacements are compared between the 2D and 3D models, between the different assumptions about fluid depressurization, and between the static and dynamic solutions. The results show that effects of dynamic amplification associated with the sudden opening of the crack in the cylinder are largely offset by the local depressurization of the fluid adjacent to the crack

  15. Crack formation and prevention in colloidal drops

    Science.gov (United States)

    Kim, Jin Young; Cho, Kun; Ryu, Seul-a; Kim, So Youn; Weon, Byung Mook

    2015-01-01

    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles. PMID:26279317

  16. Pavement Crack Detection Using Spectral Clustering Method

    Directory of Open Access Journals (Sweden)

    Jin Huazhong

    2015-01-01

    Full Text Available Pavement crack detection plays an important role in pavement maintaining and management, nowadays, which could be performed through remote image analysis. Thus, edges of pavement crack should be extracted in advance; in general, traditional edge detection methods don’t consider phase information and the spatial relationship between the adjacent image areas to extract the edges. To overcome the deficiency of the traditional approaches, this paper proposes a pavement crack detection algorithm based on spectral clustering method. Firstly, a measure of similarity between pairs of pixels is taken into account through orientation energy. Then, spatial relationship is needed to find regions where similarity between pixels in a given region is high and similarity between pixels in different regions is low. After that, crack edge detection is completed with spectral clustering method. The presented method has been run on some real life images of pavement crack, experimental results display that the crack detection method of this paper could obtain ideal result.

  17. CATALYTIC CONVERSION OF MUNICIPAL WASTE PLASTIC INTO GASOLINE-RANGE PRODUCTS OVER MESOPOROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    Jorge Norberto Beltramini

    2006-01-01

    In the last 20 years, it has become apparent that waste produced from plastics was becoming an environmental problem because of their low biodegradability. Though several methods have been proposed for recycling waste plastics, it is generally accepted that material recovery is not a long-term solution to the present problem, and that energy or chemical recovery is a more attractive alternative, including cracking into the monomer constituents, combustion to produce energy, and thermal or catalytic conversion to produce useful intermediate chemicals.This paper is a contribution in the area of the last option for energy recovery. There have been a number of publications reporting the use of molecular sieves and amorphous silica-alumina catalysts for the cracking of polymers into a range of hydrocarbons. The research work reported here demonstrates the ability of mesoporous catalysts in cracking polyethylene into gasoline range products.It was found that for mesoporous MCM-41 catalysts, its cracking activity increases with its crystallinity, displaying higher activity with smaller pore diameters. The hydrocarbon product distribution strongly indicates a carbenium ion cracking mechanism. The product distribution was also compared with those obtained from thermal cracking tests.

  18. Micro-crack enhanced permeability in tight rocks: An experimental and microstructural study

    Science.gov (United States)

    Delle Piane, Claudio; Arena, Alessio; Sarout, Joel; Esteban, Lionel; Cazes, Emilie

    2015-12-01

    The elastic and hydraulic response of a rock and its stress sensitivity are strongly affected by the presence of micro-cracks. Therefore, a full characterization and quantification of cracks at the micro-scale is essential for understanding the physical and transport properties of rocks under stress. As yet, there is no uniquely accepted method to precisely quantify the density and geometrical characteristics of such microstructural features. In this contribution, we present results of quantitative analyses of 2D scanning electron microscopy (SEM) images and 3D X-ray microtomograms acquired on three samples of Carrara Marble artificially cracked by thermal shock. New semi-automatic workflows have been developed to perform these 2D and 3D analyses. The main outcome is the quantification of average length, aspect ratio, and density per unit surface (2D) or volume (3D) of micro-cracks observed. The thermal treatment only opens grain boundaries and does not result in the creation of new intragranular cracks. The results are consistent with the degree of thermal cracking artificially induced on the rock sample prior to the imaging/analysis procedure, i.e., more and wider micro-cracks are measured on samples heated to higher temperatures. The results of these quantitative microstructural analyses are also consistent with nuclear magnetic resonance (NMR) data independently acquired on the same samples saturated with water.

  19. A catalytic distillation process for light gas oil hydrodesulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Villamil, F.D.; Marroquin, J.O.; Paz, C. de la; Rodriguez, E. [Prog. de Matematicas Aplicadas y Computacion, Prog. de Tratamiento de Crudo Maya, Instituto Mexicano del Petroleo, Mexico City, DF (Mexico)

    2004-07-01

    A light gas oil hydrodesulfurization process via catalytic distillation is developed and compared to a conventional process. By integrating the separation and reaction into a single unit, the catalytic distillation may produce a diesel with low concentration of sulfur compounds at a lower cost than the traditional reaction/separation process. The process proposed in this work is compared to an optimised conventional hydrodesulfurization unit which represents fairly well a plant that belongs to the National System of Refineries. During the optimisation of the conventional process, a compromise is established among the production of diesel and naphtha and the operating costs. The results show that the light gas oil hydrodesulfurization via catalytic distillation is as or more efficient than the conventional process. However, the removal of the sulfur compounds is carried out under less rigorous conditions. This design reduces the fix and operational costs. (author)

  20. Compact catalytic converter system for future diesel emissions standards; Kompaktes Katalysatorsystem fuer kuenftige Diesel-Emissionsnormen

    Energy Technology Data Exchange (ETDEWEB)

    Harth, Klaus [BASF Corporation, Iselin, NJ (United States)

    2012-09-15

    The Euro 6 emissions standard for diesel passenger cars will broaden the application of exhaust aftertreatment systems that use selective catalytic reduction. This will mean a further increase in the volume and complexity of the exhaust aftertreatment system. BASF has developed a compact integrated catalytic converter that combines the functions of particulate filtration and NO{sub x} reduction in a single unit. (orig.)

  1. DBEM crack propagation for nonlinear fracture problems

    Directory of Open Access Journals (Sweden)

    R. Citarella

    2015-10-01

    Full Text Available A three-dimensional crack propagation simulation is performed by the Dual Boundary Element Method (DBEM. The Stress Intensity Factors (SIFs along the front of a semi elliptical crack, initiated from the external surface of a hollow axle, are calculated for bending and press fit loading separately and for a combination of them. In correspondence of the latter loading condition, a crack propagation is also simulated, with the crack growth rates calculated using the NASGRO3 formula, calibrated for the material under analysis (steel ASTM A469. The J-integral and COD approaches are selected for SIFs calculation in DBEM environment, where the crack path is assessed by the minimum strain energy density criterion (MSED. In correspondence of the initial crack scenario, SIFs along the crack front are also calculated by the Finite Element (FE code ZENCRACK, using COD, in order to provide, by a cross comparison with DBEM, an assessment on the level of accuracy obtained. Due to the symmetry of the bending problem a pure mode I crack propagation is realised with no kinking of the propagating crack whereas for press fit loading the crack propagation becomes mixed mode. The crack growth analysis is nonlinear because of normal gap elements used to model the press fit condition with added friction, and is developed in an iterative-incremental procedure. From the analysis of the SIFs results related to the initial cracked configuration, it is possible to assess the impact of the press fit condition when superimposed to the bending load case.

  2. Investigation of corrosion cracks in PGV-1000 collector studs

    International Nuclear Information System (INIS)

    Metallographic control of the primary circuit stubs in the Kozloduy NPP unit 6 have shown numerous corrosion cracks in the perlite steel 38GN2MFA. Samples cut from the surfaces of studs with different corrosion cracks are examined by optical microscopy (Neophot), electron microscopy with quantitative analysis (JEOL SuperProbe), photo-electron spectroscopy, X-ray diffraction, X-ray fluorescence analysis and Moessbauer spectroscopy. The results showed considerable changes in thickness and chemical composition of the phosphate coating. For the first time Pb is detected on the surface of WWER-1000 steam generator studs. Possible corrosion mechanisms are discussed taking into account the phosphate coating technology applied for the stubs

  3. Transition from Multiple Macro-Cracking to Multiple Micro-Cracking in Cementitious Composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun; LENG Bing

    2008-01-01

    This paper presents an experimental study of the possibility of transition from multiple macro-cracking to multiple micro-cracking in cementitious composites.Conventional polyvinyl alcohol fiber reinforced cementitious composites normally exhibit macroscopic strain-hardening and multiple cracking after the first cracks appear.However,the individual crack width at the saturated stage is normally 60 to 80 μm.In the current study,the effect of fine aggregate size on the cracking performance,especially the individual crack width in the strain-hardening stage was studied by bending tests.The results show that the individual crack widths can be reduced from 60-80 μm to 10-30 μm by modifying the particle size of the fine aggregates used in the composites.

  4. Impact of severe cracked germanium (111) substrate on aluminum indium gallium phosphate light-emitting-diode's electro-optical performance

    Science.gov (United States)

    Annaniah, Luruthudass; Devarajan, Mutharasu

    2016-07-01

    Cracked die is a serious failure mode in the Light Emitting Diode (LED) industry - affecting LED quality and long-term reliability performance. In this paper an investigation has been carried out to find the correlation between severe cracked germanium (Ge) substrate of an aluminum indium gallium phosphate (AlInGaP) LED and its electro-optical performance after the Temperature Cycle (TC) test. The LED dice were indented at several bond forces using a die bonder. The indented dice were analysed using a Scanning Electron Microscope (SEM). The result showed that severe cracks were observed at 180 gF onward. As the force of indentation increases, crack formation also becomes more severe thus resulting in the chipping of the substrate. The cracked dies were packaged and the TC test was performed. The results did not show any electro-optical failure or degradation, even after a 1000 cycle TC test. Several mechanically cross-sectioned cracked die LEDs, were analysed using SEM and found that no crack reached the active layer. This shows that severely cracked Ge substrate are able to withstand a -40°C/+100°C TC test up to 1000 cycles and LED optical performance is not affected. A small leakage current was observed in all of the cracked die LEDs in comparison to the reference unit. However, this value is smaller than the product specification and is of no concern.

  5. Automatic crack length measurement, inductive and videoelectronic

    International Nuclear Information System (INIS)

    Tracking of crack propagation with a small fault of less than 2% is permitted by two recently developed methods. Because of the direct manner of crack inspection, the video-electronic method has the advantage over the inductive measurement, although with a scanning frequency given by television control, only relatively small crack velocities as compared with the inductive method can be detected with sufficient accuracy. Because of strong material contraction at the crack top with both methods, minor measurement adulterations may arise. The equipment causes relatively low costs during operation. Both methods enable fully automatic evaluation and control of the experiment. (orig.)

  6. Fatigue crack growth detect, assess, avoid

    CERN Document Server

    Richard, Hans Albert

    2016-01-01

    This book offers a concise introduction to fatigue crack growth, based on practical examples. It discusses the essential concepts of fracture mechanics, fatigue crack growth under constant and variable amplitude loading and the determination of the fracture-mechanical material parameters. The book also introduces the analytical and numerical simulation of fatigue crack growth as well as crack initiation. It concludes with a detailed description of several practical case studies and some exercises. The target group includes graduate students, researchers at universities and practicing engineers.

  7. Expansive Soil Crack Depth under Cumulative Damage

    Directory of Open Access Journals (Sweden)

    Bei-xiao Shi

    2014-01-01

    Full Text Available The crack developing depth is a key problem to slope stability of the expansive soil and its project governance and the crack appears under the roles of dry-wet cycle and gradually develops. It is believed from the analysis that, because of its own cohesion, the expansive soil will have a certain amount of deformation under pulling stress but without cracks. The soil body will crack only when the deformation exceeds the ultimate tensile strain that causes cracks. And it is also believed that, due to the combined effect of various environmental factors, particularly changes of the internal water content, the inherent basic physical properties of expansive soil are weakened, and irreversible cumulative damages are eventually formed, resulting in the development of expansive soil cracks in depth. Starting from the perspective of volumetric strain that is caused by water loss, considering the influences of water loss rate and dry-wet cycle on crack developing depth, the crack developing depth calculation model which considers the water loss rate and the cumulative damages is established. Both the proposal of water loss rate and the application of cumulative damage theory to the expansive soil crack development problems try to avoid difficulties in matrix suction measurement, which will surely play a good role in promoting and improving the research of unsaturated expansive soil.

  8. Slow crack growth in polycarbonate films

    CERN Document Server

    Cortet, Pierre-Philippe; Vanel, Loic; Ciliberto, Sergio

    2005-01-01

    We study experimentally the slow growth of a single crack in polycarbonate films submitted to uniaxial and constant imposed stress. The specificity of fracture in polycarbonate films is the appearance of flame shaped macroscopic process zones at the tips of the crack. Supported by an experimental study of the mechanical properties of polycarbonate films, an analysis of the stress dependence of the mean ratio between the process zone and crack lengths, during the crack growth, show a quantitative agreement with the Dugdale-Barenblatt model of the plastic process zone. We find that the fracture growth curves obey strong scaling properties that lead to a well defined growth master curve.

  9. Crack depth determination with inductive thermography

    Science.gov (United States)

    Oswald-Tranta, B.; Schmidt, R.

    2015-05-01

    Castings, forgings and other steel products are nowadays usually tested with magnetic particle inspection, in order to detect surface cracks. An alternative method is active thermography with inductive heating, which is quicker, it can be well automated and as in this paper presented, even the depth of a crack can be estimated. The induced eddy current, due to its very small penetration depth in ferro-magnetic materials, flows around a surface crack, heating this selectively. The surface temperature is recorded during and after the short inductive heating pulse with an infrared camera. Using Fourier transformation the whole IR image sequence is evaluated and the phase image is processed to detect surface cracks. The level and the local distribution of the phase around a crack correspond to its depth. Analytical calculations were used to model the signal distribution around cracks with different depth and a relationship has been derived between the depth of a crack and its phase value. Additionally, also the influence of the heating pulse duration has been investigated. Samples with artificial and with natural cracks have been tested. Results are presented comparing the calculated and measured phase values depending on the crack depth. Keywords: inductive heating, eddy current, infrared

  10. Wettability Induced Crack Dynamics and Morphology

    CERN Document Server

    Ghosh, Udita Uday; Bhandari, Aditya Bikram; Chakraborty, Suman; DasGupta, Sunando

    2014-01-01

    Substrate wettability alteration induced control over crack formation process in thin colloidal films has been addressed in the present study. Colloidal nanosuspension (53nm, mean particle diameter) droplets have been subjected to natural drying to outline the effects of substrate surface energies over the dry-out characteristics with emphasis on crack dynamics, crack morphology and underlying particle arrangements. Experimental findings indicate that number of cracks formed decreases with increase in substrate hydrophobicity. These physical phenomena have been explained based on the magnitude of stress dissipation incurred by the substrate. DLVO predictions are also found to be in tune with the reported experimental investigations.

  11. Dynamics of cracking in drying colloidal sheets.

    Science.gov (United States)

    Sengupta, Rajarshi; Tirumkudulu, Mahesh S

    2016-04-01

    Colloidal dispersions are known to display a fascinating network of cracks on drying. We probe the fracture mechanics of free-standing films of aqueous polymer-particle dispersions. Thin films of the dispersion are cast between a pair of plain steel wires and allowed to dry under ambient conditions. The strain induced on the particle network during drying is relieved by cracking. The stress which causes the films to crack has been calculated by measuring the deflection of the wires. The critical cracking stress varied inversely to the two-thirds' power of the film thickness. We also measure the velocity of the tip of a moving crack. The motion of a crack has been modeled as a competition between the release of the elastic energy stored in the particle network, the increase in surface energy as a result of the growth of a crack, the rate of viscous dissipation of the interstitial fluid and the kinetic energy associated with a moving crack. There is fair agreement between the measured crack velocities and predictions. PMID:26924546

  12. Investigations of Low Temperature Time Dependent Cracking

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sluys, W A; Robitz, E S; Young, B A; Bloom, J

    2002-09-30

    The objective of this project was to investigate metallurgical and mechanical phenomena associated with time dependent cracking of cold bent carbon steel piping at temperatures between 327 C and 360 C. Boiler piping failures have demonstrated that understanding the fundamental metallurgical and mechanical parameters controlling these failures is insufficient to eliminate it from the field. The results of the project consisted of the development of a testing methodology to reproduce low temperature time dependent cracking in laboratory specimens. This methodology was used to evaluate the cracking resistance of candidate heats in order to identify the factors that enhance cracking sensitivity. The resultant data was integrated into current available life prediction tools.

  13. Surface effects and assessment of crack propagation

    International Nuclear Information System (INIS)

    A realistic analysis of microcrack interaction at stress concentrations require a three dimensional analysis, and evaluation of fracture parameters along the crack front. Due to its complexity the problem can only be tackled through computational techniques. In this work, we describe the use of the Boundary Element Technique for analysis of surface effects at crack vertex. It is shown that the existence of a vertex singularity at this location poses limitations on actual crack geometries, and hence some common assumptions might not be adequate for a realistic description of surface crack growth. (author). 15 refs, 5 figs

  14. Catalytic quantum error correction

    CERN Document Server

    Brun, T; Hsieh, M H; Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

    2006-01-01

    We develop the theory of entanglement-assisted quantum error correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to pre-shared entanglement. Conventional stabilizer codes are equivalent to dual-containing symplectic codes. In contrast, EAQEC codes do not require the dual-containing condition, which greatly simplifies their construction. We show how any quaternary classical code can be made into a EAQEC code. In particular, efficient modern codes, like LDPC codes, which attain the Shannon capacity, can be made into EAQEC codes attaining the hashing bound. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes which maintain a region of inherited noiseless qubits. We also give an alternative construction of EAQEC codes by making classical entanglement assisted codes coherent.

  15. Fatigue Crack Closure Analysis Using Digital Image Correlation

    Science.gov (United States)

    Leser, William P.; Newman, John A.; Johnston, William M.

    2010-01-01

    Fatigue crack closure during crack growth testing is analyzed in order to evaluate the critieria of ASTM Standard E647 for measurement of fatigue crack growth rates. Of specific concern is remote closure, which occurs away from the crack tip and is a product of the load history during crack-driving-force-reduction fatigue crack growth testing. Crack closure behavior is characterized using relative displacements determined from a series of high-magnification digital images acquired as the crack is loaded. Changes in the relative displacements of features on opposite sides of the crack are used to generate crack closure data as a function of crack wake position. For the results presented in this paper, remote closure did not affect fatigue crack growth rate measurements when ASTM Standard E647 was strictly followed and only became a problem when testing parameters (e.g., load shed rate, initial crack driving force, etc.) greatly exceeded the guidelines of the accepted standard.

  16. Crack spacing of unsaturated soils in the critical state

    Institute of Scientific and Technical Information of China (English)

    SUN JiChao; WANG GuangQian; SUN QiCheng

    2009-01-01

    The cracking mechanism of unsaturated soils due to evaporation is poorly understood, and the magnitude of crack spacing is usually hard to estimate. In this work, cracks were postulated to occur suc-cedently rather than simultaneously, that is, secondary cracks appear after primary cracks as evaporation continues. Formulae of the secondary crack spacing and secondary trend crack spacing were then derived after stress analysis. The calculated spacing values were consistent with the published experimental data. Meanwhile, the effect of the Poisson ratio on the crack spacing was analyzed, which showed that the magnitude of crack spacing was proportional to the Poisson ratio in the range of [0.30,0.35].

  17. Effect of Crack Closure on Ultrasonic Detection of Fatigue Cracks at Fastener Holes

    Science.gov (United States)

    Bowles, S. J.; Harding, C. A.; Hugo, G. R.

    2009-03-01

    The ultrasonic response from closed fatigue cracks grown in aluminium alloy specimens using a representative aircraft spectrum loading has been characterised as a function of tensile applied load using pulse-echo 45° shear-wave ultrasonic C-scans with focused immersion transducers. Observed trends with crack size and applied load are described and compared to results for artificial machined defects. The results demonstrate that crack closure significantly reduces the ultrasonic response compared to open cracks or machined defects.

  18. Mode Ⅰ Plane Crack Interacting with an Interfacial Crack Along a Circular Inhomogeneity

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; MA Jian-jun; LIU Zheng-guang

    2006-01-01

    The elastic interaction of the mode Ⅰ plane crack with an interfacial crack along a circular inhomogeneity is dealt with. The dislocation density and the stress intensity factors (SIFs) of the mode I plane crack are obtained numerically. A new kind of dislocation equilibrium equation about the plane crack is applied. The influence of some material parameters on the dislocation density and SIFs are analyzed.

  19. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  20. Cracking of an Aircraft Wheel Rim Made From Al-Alloy 2014-T6

    Directory of Open Access Journals (Sweden)

    G. Kosec

    2010-10-01

    Full Text Available Generally failures of different aircraft components and parts are revealed and examined by the use of non-destructive examination methods. In further detailed explanation and interpretation of failures optical and scanning electron microscopy are used. This paper deals with a problem of a crack on aircraft wheel rim made from aluminium alloy 2014-T6.The crack was observed during regular control by the maintenance unit for non-destructive examination of the Slovenian air carrier Adria Airways. The crack on the rim of an aircraft wheel investigated was a typical fatigue crack. At same time a numerous pits were found which served as stress concentrations on the rim surface.

  1. Improvement of flue gas selective catalytic reduction technology and equipment for propane dehydrogenation (PDH) unit%丙烷脱氢装置烟气脱硝技术与设备改造

    Institute of Scientific and Technical Information of China (English)

    刘唯奇; 张国甫; 高海见; 陈金锋

    2016-01-01

    为降低烟气中的氮氧化物含量,采用丹麦托普索公司催化剂和工艺技术,在烟气余热锅炉内增加脱硝段,以满足达标排放的目的.并与工程公司合作,优化脱硝注氨系统的工艺流程,减少氨水消耗量,降低氨逃逸浓度.技术与设备改进后,烟色得到改善,烟气中的NOx含量大幅降低,同时氨水消耗量低于设计值,产生了良好的环境效益和经济效益.%The NOx concentration in the flue gas is reduced for standardized emission by a selective catalytic reduction (SCR) reactor installed in the waste heat boiler.The catalyst and reactor design are provided by Denmark HALDOR TOPSOE.New ammonia injection process is studied with engineering company to reduce ammonia consumption and slip concentration.After the improvement of process and equipment,the colour of flue gas looks better than before.The flue gas NOx concentration is significantly decreased and ammonia consumption is lower than hte design value,which produce good environmental and economic benefits.

  2. Extended propagation model for interfacial crack in composite material structure

    Institute of Scientific and Technical Information of China (English)

    闫相桥; 冯希金

    2002-01-01

    An interfacial crack is a common damage in a composite material structure . An extended propaga-tion model has been established for an interfacial crack to study the dependence of crack growth on the relativesizes of energy release rates at left and right crack tips and the properties of interfacial material characterize thegrowth of interfacial crack better.

  3. Chloride Penetration through Cracks in High-Performance Concrete and Surface Treatment System for Crack Healing

    Directory of Open Access Journals (Sweden)

    In-Seok Yoon

    2012-01-01

    Full Text Available For enhancing the service life of concrete structures, it is very important to minimize crack at surface. Even if these cracks are very small, the problem is to which extend these cracks may jeopardize the durability of these decks. It was proposed that crack depth corresponding with critical crack width from the surface is a crucial factor in view of durability design of concrete structures. It was necessary to deal with chloride penetration through microcracks characterized with the mixing features of concrete. This study is devoted to examine the effect of high strength concrete and reinforcement of steel fiber on chloride penetration through cracks. High strength concrete is regarded as an excellent barrier to resist chloride penetration. However, durability performance of cracked high strength concrete was reduced seriously up to that of ordinary cracked concrete. Steel fiber reinforcement is effective to reduce chloride penetration through cracks because steel fiber reinforcement can lead to reduce crack depth significantly. Meanwhile, surface treatment systems are put on the surface of the concrete in order to seal the concrete. The key-issue is to which extend a sealing is able to ensure that chloride-induced corrosion can be prevented. As a result, penetrant cannot cure cracks, however, coating and combined treatment can prevent chloride from flowing in concrete with maximum crack width of 0.06 mm and 0.08 mm, respectively.

  4. Interfacial Crack Arrest in Sandwich Panels with Embedded Crack Stoppers Subjected to Fatigue Loading

    DEFF Research Database (Denmark)

    Martakos, G.; Andreasen, J. H.; Berggreen, Christian;

    2016-01-01

    A novel crack arresting device has been implemented in sandwich panels and tested using a special rig to apply out-of-plane loading on the sandwich panel face-sheets. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect...

  5. What can cracked polymer do

    Science.gov (United States)

    Jiao, Kexin; Zhou, Chuanhong; Kohli, Punit; Poudel, Anish; Chu, Tsuchin

    2015-03-01

    Buckling, delamination, and cracking are very well known phenomenon observed in most thin films. They were theoretically explained by the existence of mechanical instability due to the residue stress generated when a thin film is deposited on substrates or undergoing environmental stimulus. Buckled structures at micro- or nano-scale have been of great interests and have been used extensively in many applications including particles self-assembling, surface wettability modification, and micro-electronic device fabrication. However, peeling of a layer from a substrate due to delamination or fractures on a thin film due to cracking is mostly taken as an undesirable result. Therefore, strategies are inspired for preventing or removing these often undesired structures. We found that after being heated above its decomposition temperature and then cooled to room temperature, a PDMS thin film showed micro-fibers of 100 μm width and up to 1.5 cm in length. By studying the formation mechanism, control of the dimensions and of the growth pattern on a substrate for PDMS micro-fibers were realized. Giving credit to their high flexibility and optical transparency, a PDMS micro-fiber were utilized in high resolution near field imaging achieved by attaching a micro-lens on the fiber. Interestingly, a surface covered by PDMS micro-fibers will turn from superhydrophobic into superhydrophilic by further heating providing potential applications in surface wettability modification. In future, we will investigate and simulate the growth of PDMS micro-fiber and look for more possible applications.

  6. Unsteady catalytic processes and sorption-catalytic technologies

    International Nuclear Information System (INIS)

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  7. Unsteady catalytic processes and sorption-catalytic technologies

    Energy Technology Data Exchange (ETDEWEB)

    Zagoruiko, A N [G.K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-07-31

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  8. Development of crack shape: LBB methodology for cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Moulin, D.; Chapuliot, S.; Drubay, B. [Commissariat a l Energie Atomique, Gif sur Yvette (France)

    1997-04-01

    For structures like vessels or pipes containing a fluid, the Leak-Before-Break (LBB) assessment requires to demonstrate that it is possible, during the lifetime of the component, to detect a rate of leakage due to a possible defect, the growth of which would result in a leak before-break of the component. This LBB assessment could be an important contribution to the overall structural integrity argument for many components. The aim of this paper is to review some practices used for LBB assessment and to describe how some new R & D results have been used to provide a simplified approach of fracture mechanics analysis and especially the evaluation of crack shape and size during the lifetime of the component.

  9. Unité micropilote pour l'étude de charges de vapocraquage. Exemple d'un mélange de normales paraffines Micropilot Plant for the Study of Steam-Cracking Feedstocks. Example of a Mixture of Normal Paraffins

    Directory of Open Access Journals (Sweden)

    Billaud F.

    2006-11-01

    Full Text Available La décomposition thermique d'un mélange de normales paraffines (nom commercial Solpar , provenance British Petroleum a été étudiée dans une unité micropilote entre 640 et 820 °C ; les produits principaux dosés par chromatographie en phase gazeuse sont : hydrogène, méthane, éthylène, propène, butène-1, pentène-1, hexène-1, heptène-1, octène-1 et nonène-1. Un des intérêts du travail est la description mécanistique de la pyrolyse d'un hydrocarbure lourd qui permet d'interpréter la formation primaire de ces produits principaux. On a aussi montré expérimentalement l'intérêt du vapocraquage haute température et faible temps de séjour lorsque l'on veut produire sélectivement des oléfines légères en minimisant la production d'aromatiques. The thermal decomposition of a mixture of normal paraffins (trademark Solpar, by British Petroleum has been studied in a micropilot plant in a temperature range of 640 to 820°C. The main products determined by gas chromatography are hydrogen, methane, ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-nonene. On of the important results of the present work is the mechanistic description of heavy hydrocarbon pyrolysis so that the primary formation of these principal products can be interpreted. Moreover, the advantage of using high-temperature steam cracking and short residence time for the selective production of light olefins, thus minimizing production of aromatics, is experimentally demonstrated.

  10. Novel Catalytic Reactor for CO2 Reduction via Sabatier Process Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes to develop a novel, efficient, and lightweight catalytic Sabatier CO2 methanation unit, capable of converting a mixture of...

  11. Dense ceramic catalytic membranes and membrane reactors for energy and environmental applications.

    Science.gov (United States)

    Dong, Xueliang; Jin, Wanqin; Xu, Nanping; Li, Kang

    2011-10-21

    Catalytic membrane reactors which carry out separation and reaction in a single unit are expected to be a promising approach to achieve green and sustainable chemistry with less energy consumption and lower pollution. This article presents a review of the recent progress of dense ceramic catalytic membranes and membrane reactors, and their potential applications in energy and environmental areas. A basic knowledge of catalytic membranes and membrane reactors is first introduced briefly, followed by a short discussion on the membrane materials including their structures, composition and strategies for material development. The configuration of catalytic membranes, the design of membrane reaction processes and the high temperature sealing are also discussed. The performance of catalytic membrane reactors for energy and environmental applications are summarized and typical catalytic membrane reaction processes are presented and discussed. Finally, current challenges and difficulties related to the industrialization of dense ceramic membrane reactors are addressed and possible future research is also outlined.

  12. Model of a catalytic injection in a riser by means of gamma ray transmission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Alex E.; Brito, Macio F.P.; Dantas, Carlos C.; Melo, Silvio B., E-mail: alex.emoura@ufpe.br, E-mail: sbm@ufpe.br [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil); Barbosa, Enivaldo S., E-mail: Enivaldo.santos@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia Mecanica; Lima, Emerson A.O., E-mail: eal@poli.br [Universidade de Pernambuco, Recife, PE (Brazil). Departamento de Matematica

    2015-07-01

    In Gas solid process involving a solid circulation through a closed loop the knowledge of the Solids Circulation Rate (SCR) is fundamental to control and improve the operation of a circulating fluidized bed system. A valve controls the circulation rate of solids in the riser of a fluid catalytic cracking unit. Initially, to control the catalyst injection in the riser, a rotary valve controlled and measured solid flow injection, but with a limited working time. Due to the fine powder catalyst abrasive action on the valve steel axis, this device stop work. A lab made valve were design to avoiding direct contact of the catalyst with mechanical moving parts in while control solid injection in riser, but do not measure the solid flow like the rotary valve. To control the lab made device a fixed pressure measurement at riser bottom is provided by control setup which corresponds to a given mass/time solid injection. In the present work, we proposed a method to evaluate the control valve based on a non-invasive technique. With gamma ray transmission measurements, in a cross section of the pipe, we developed a model that was used in the control system of the Cold Pilot Unit (CPU). Therefore, the interaction of the gamma ray with solid flow in riser should yield the necessary information for the process control system. A first model approximation consider the solid flow rate injection and solid velocity in riser as proposed in literature. In the CPU control system a Programmable Logic Controller-PLC keeps steady state processing the airflow, pressure profile and solid flow inputs. Additionally to preexisting PLC platform, some LabVIEW algorithms were implemented to achieve a good system performance operational condition. (author)

  13. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    The focus of this thesis is the catalytic production of diesel from biomass, especially emphasising catalytic conversion of waste vegetable oils and fats. In chapter 1 an introduction to biofuels and a review on different catalytic methods for diesel production from biomass is given. Two of these methods have been used industrially for a number of years already, namely the transesterification (and esterification) of oils and fats with methanol to form fatty acid methyl esters (FAME), and the hydrodeoxygenation (HDO) of fats and oils to form straight-chain alkanes. Other possible routes to diesel include upgrading and deoxygenation of pyrolysis oils or aqueous sludge wastes, condensations and reductions of sugars in aqueous phase (aqueous-phase reforming, APR) for monofunctional hydrocarbons, and gasification of any type of biomass followed by Fischer-Tropsch-synthesis for alkane biofuels. These methods have not yet been industrialised, but may be more promising due to the larger abundance of their potential feedstocks, especially waste feedstocks. Chapter 2 deals with formation of FAME from waste fats and oils. A range of acidic catalysts were tested in a model fat mixture of methanol, lauric acid and trioctanoin. Sulphonic acid-functionalised ionic liquids showed extremely fast convertion of lauric acid to methyl laurate, and trioctanoate was converted to methyl octanoate within 24 h. A catalyst based on a sulphonated carbon-matrix made by pyrolysing (or carbonising) carbohydrates, so-called sulphonated pyrolysed sucrose (SPS), was optimised further. No systematic dependency on pyrolysis and sulphonation conditions could be obtained, however, with respect to esterification activity, but high activity was obtained in the model fat mixture. SPS impregnated on opel-cell Al{sub 2}O{sub 3} and microporous SiO{sub 2} (ISPS) was much less active in the esterification than the original SPS powder due to low loading and thereby low number of strongly acidic sites on the

  14. Corrosion and Cracking of Reinforced Concrete

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Modelling of the deterioration of reinforced concrete has in recent years changed from being a deterministic modelling based on experience to be stochastic modelling based on sound and consistent physical, chemical and mechanical principles. In this paper is presented a brief review of modern mod...... for time to initial corrosion, time to initial cracking, and time to a given crack width may be obtained....

  15. Sulfide stress cracking of pipeline steels

    International Nuclear Information System (INIS)

    The problem of the sulfide stress corrosion cracking of pipeline steels and their welded joints have been presented for pipeline steels. Results of hydrogen sulfide stress cracking inhibitors and corrosion inhibitors of three types protective actions on pipeline steels of two grades petroleum range of products are given. (author)

  16. Crack Formation in Grouted Annular Composite

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    The objective of the present analysis is to identify the reason for extensive crack formation which occurred during an annulus grouting performance test, to evaluate possible consequences of the cracking, and to recommend measures to be taken in order to avoid similar problems in the future....

  17. Problems in fracture mechanics of indentation cracks

    International Nuclear Information System (INIS)

    Vickers indentation cracks are an appropriate tool to determine the crack-tip toughness K10 of ceramics from the total crack opening displacements. Two different procedures were applied to determine the crack opening displacement (COD) field under residual and externally applied stress fields. First, a semi-analytical procedure was used to compute the COD field from residual stresses introduced in the uncracked body by the indentation test. This approach allows a description by analytical relations. In order to check the accuracy of these calculations and to outline some problems in detail, also finite element (FE) computations were carried out. In an experimental example the stress intensity factor of glass is determined. Apart from the crack opening profile, also relations for the total stress intensity factor and the T-stress term are provided. As a second type of indentation crack, cone cracks were considered as developing under spherical contact load. Mixed-mode stress intensity factors were computed. The results obtained by application of the weight function method are used to calculate the cone angle under the condition of K11=0 during crack generation. A good agreement with measured data from literature is found. (orig.)

  18. Crack propagation directions in unfilled resins.

    Science.gov (United States)

    Baran, G; Sadeghipour, K; Jayaraman, S; Silage, D; Paul, D; Boberick, K

    1998-11-01

    Posterior composite restorative materials undergo accelerated wear in the occlusal contact area, primarily through a fatigue mechanism. To facilitate the timely development of new and improved materials, a predictive wear model is desirable. The objective of this study was to develop a finite element model enabling investigators to predict crack propagation directions in resins used as the matrix material in composites, and to verify these predictions by observing cracks formed during the pin-on-disc wear of a 60:40 BISGMA:TEGDMA resin and an EBPADMA resin. Laser confocal scanning microscopy was used to measure crack locations. Finite element studies were done by means of ABAQUS software, modeling a cylinder sliding on a material with pre-existing surface-breaking cracks. Variables included modulus, cylinder/material friction coefficient, crack face friction, and yield behavior. Experimental results were surprising, since most crack directions were opposite previously published observations. The majority of surface cracks, though initially orthogonal to the surface, changed direction to run 20 to 30 degrees from the horizontal in the direction of indenter movement. Finite element modeling established the importance of subsurface shear stresses, since calculations provided evidence that cracks propagate in the direction of maximum K(II)(theta), in the same direction as the motion of the indenter, and at an angle of approximately 20 degrees. These findings provide the foundation for a predictive model of sliding wear in unfilled glassy resins.

  19. Uncertainty Quantification in Fatigue Crack Growth Prognosis

    Directory of Open Access Journals (Sweden)

    Shankar Sankararaman

    2011-01-01

    Full Text Available This paper presents a methodology to quantify the uncertainty in fatigue crack growth prognosis, applied to structures with complicated geometry and subjected to variable amplitude multi-axial loading. Finite element analysis is used to address the complicated geometry and calculate the stress intensity factors. Multi-modal stress intensity factors due to multi-axial loading are combined to calculate an equivalent stress intensity factor using a characteristic plane approach. Crack growth under variable amplitude loading is modeled using a modified Paris law that includes retardation effects. During cycle-by-cycle integration of the crack growth law, a Gaussian process surrogate model is used to replace the expensive finite element analysis. The effect of different types of uncertainty – physical variability, data uncertainty and modeling errors – on crack growth prediction is investigated. The various sources of uncertainty include, but not limited to, variability in loading conditions, material parameters, experimental data, model uncertainty, etc. Three different types of modeling errors – crack growth model error, discretization error and surrogate model error – are included in analysis. The different types of uncertainty are incorporated into the crack growth prediction methodology to predict the probability distribution of crack size as a function of number of load cycles. The proposed method is illustrated using an application problem, surface cracking in a cylindrical structure.

  20. Strength of Cracked Reinforced Concrete Disks

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1999-01-01

    The paper deals with models, based on the theory of plasticity, to be used in strength assessments of reinforced concrete disks suffering from different kinds of cracking. Based on the assumption that the sliding strength of concrete is reduced in sections where cracks are located, solutions...

  1. Partial regeneration of Ni-based catalysts for hydrogen production via methane cracking part II: modeling and optimization

    OpenAIRE

    KOÇ, Reyyan; ALPER, Erdoğan; ELKAMEL, Eric CROISET and Ali

    2009-01-01

    High purity, carbon monoxide-free hydrogen and filamentous carbon can be produced by thermo-catalytic cracking of methane. Carbon filaments continue to grow until the catalyst deactivates because of carbon encapsulation. Regeneration of catalyst is important to maintain a continuous process. Our work on optimization of the partial regeneration method showed that activity of the catalyst can be sustained for longer times by gasifying not all but some extent of the deposited carbon. I...

  2. The geometry of soil crack networks

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    The subject of this work is the modification and specification of an approach to detail the estimation of soil crack network characteristics. The modification aims at accounting for the corrected soil crack volume based on the corrected shrinkage geometry factor compared to known estimates of crack volume and shrinkage geometry factor. The mode of the correction relies on recent results of the soil reference shrinkage curve. The main exposition follows the preliminary brief review of available approaches to dealing with the geometry of soil crack networks and gives a preliminary brief summary of the approach to be modified and specified. To validate and illustrate the modified approach the latter is used in the analysis of available data on soil cracking in a lysimeter.

  3. XFEM for Thermal Crack of Massive Concrete

    Directory of Open Access Journals (Sweden)

    Guowei Liu

    2013-01-01

    Full Text Available Thermal cracking of massive concrete structures occurs as a result of stresses caused by hydration in real environment conditions. The extended finite element method that combines thermal fields and creep is used in this study to analyze the thermal cracking of massive concrete structures. The temperature field is accurately simulated through an equivalent equation of heat conduction that considers the effect of a cooling pipe system. The time-dependent creep behavior of massive concrete is determined by the viscoelastic constitutive model with Prony series. Based on the degree of hydration, we consider the main properties related to cracking evolving with time. Numerical simulations of a real massive concrete structure are conducted. Results show that the developed method is efficient for numerical calculations of thermal cracks on massive concrete. Further analyses indicate that a cooling system and appropriate heat preservation measures can efficiently prevent the occurrence of thermal cracks.

  4. Probabilistic analysis of linear elastic cracked structures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a probabilistic methodology for linear fracture mechanics analysis of cracked structures. The main focus is on probabilistic aspect related to the nature of crack in material. The methodology involves finite element analysis; statistical models for uncertainty in material properties, crack size, fracture toughness and loads; and standard reliability methods for evaluating probabilistic characteristics of linear elastic fracture parameter. The uncertainty in the crack size can have a significant effect on the probability of failure, particularly when the crack size has a large coefficient of variation. Numerical example is presented to show that probabilistic methodology based on Monte Carlo simulation provides accurate estimates of failure probability for use in linear elastic fracture mechanics.

  5. Crack spacing threshold of double cracks propagation for large-module rack

    Institute of Scientific and Technical Information of China (English)

    赵铁柱; 石端伟; 姚哲皓; 毛宏勇; 程术潇; 彭惠

    2015-01-01

    Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propagation rule and the residual life estimation method of large-module rack is of great significance. The possible crack distribution forms of the rack in the Three Gorges shiplift were studied. By applying moving load on the model in FRANC3D and ANSYS, quantitative analyses of interference effects on double cracks in both collinear and offset conditions were conducted. The variation rule of the stress intensity factor (SIF) influence factor,RK, of double collinear cracks changing with crack spacing ratio,RS, was researched. The horizontal and vertical crack spacing threshold of double cracks within the design life of the shiplift were obtained, which are 24 and 4 times as large as half of initial crack length,c0, respectively. The crack growth rates along the length and depth directions in the process of coalescence on double collinear cracks were also studied.

  6. Unsaturated Seepage Analysis of Cracked Soil including Development Process of Cracks

    Directory of Open Access Journals (Sweden)

    Ling Cao

    2016-01-01

    Full Text Available Cracks in soil provide preferential pathways for water flow and their morphological parameters significantly affect the hydraulic conductivity of the soil. To study the hydraulic properties of cracks, the dynamic development of cracks in the expansive soil during drying and wetting has been measured in the laboratory. The test results enable the development of the relationships between the cracks morphological parameters and the water content. In this study, the fractal model has been used to predict the soil-water characteristic curve (SWCC of the cracked soil, including the developmental process of the cracks. The cracked expansive soil has been considered as a crack-pore medium. A dual media flow model has been developed to simulate the seepage characteristics of the cracked expansive soil. The variations in pore water pressure at different part of the model are quite different due to the impact of the cracks. This study proves that seepage characteristics can be better predicted if the impact of cracks is taken into account.

  7. Estimation of Fatigue Crack Growth Behavior of Cracked Specimen Under Mixed-mode Loads

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jeong Woo [KIMM, Daejeon (Korea, Republic of); Woo, Eun Taek; Han, Seung Ho [Dong-A University, Busan (Korea, Republic of)

    2015-07-15

    To estimate the fatigue crack propagation behavior of compact tension shear (CTS) specimen under mixed-mode loads, crack path prediction theories and Tanaka’s equation were applied. The stress intensity factor at a newly created crack tip was calculated using a finite element method via ANSYS, and the crack path and crack increment were then obtained from the crack path prediction theories, Tanaka’s equation, and the Paris’ equation, which were preprogrammed in Microsoft Excel. A new method called the finite element crack tip updating method (FECTUM) was developed. In this method, the finite element method and Microsoft Excel are used to calculate the stress intensity factors and the crack path, respectively, at the crack tip per each crack increment. The developed FECTUM was applied to simulate the fatigue crack propagation of a single-edge notched bending (SENB) specimen under eccentric three-point bending loads. The results showed that the number of cycles to failure of the specimen obtained experimentally and numerically were in good agreement within an error range of less than 3%.

  8. Crack shape developments and leak rates for circumferential complex-cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Brickstad, B.; Bergman, M. [SAQ Inspection Ltd., Stockholm (Sweden)

    1997-04-01

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  9. Fully plastic crack opening analyses of complex-cracked pipes for Ramberg-Osgood materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Uk; Choi, Jae Boong [Sungkyunkwan University, Suwon (Korea, Republic of); Huh, Nam Su [Seoul National University, Seoul (Korea, Republic of); Kim, Yun Jae [Korea University, Seoul (Korea, Republic of)

    2016-04-15

    The plastic influence functions for calculating fully plastic Crack opening displacement (COD) of complex-cracked pipes were newly proposed based on systematic 3-dimensional (3-D) elastic-plastic Finite element (FE) analyses using Ramberg-Osgood (R-O) relation, where global bending moment, axial tension and internal pressure are considered separately as a loading condition. Then, crack opening analyses were performed based on GE/EPRI concept by using the new plastic influence functions for complex-cracked pipes made of SA376 TP304 stainless steel, and the predicted CODs were compared with FE results based on deformation plasticity theory of tensile material behavior. From the comparison, the confidence of the proposed fully plastic crack opening solutions for complex-cracked pipes was gained. Therefore, the proposed engineering scheme for COD estimation using the new plastic influence functions can be utilized to estimate leak rate of a complex-cracked pipe for R-O material.

  10. On fatigue crack growth in ductile materials by crack-tip blunting

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2004-01-01

    One of the basic mechanisms for fatigue crack growth in ductile metals is that depending on crack-tip blunting under tensile loads and re-sharpening of the crack-tip during unloading. In a standard numerical analysis accounting for finite strains it is not possible to follow this process during...... many cycles, as severe mesh distortion at the crack-tip results from the huge geometry changes developing during the cyclic plastic straining. In the present numerical studies, based on an elastic-perfectly plastic material model, crack growth computations are continued up to 200 full cycles by using...... remeshing at several stages of the plastic deformation. Three different values of the load ratio R = K-min/K-max are considered. It is shown that the crack-up opening displacement, CTOD, typically undergoes a transient behaviour, with no crack closure during many cycles, before a steady-state cycling...

  11. Crack Growth in Concrete Gravity Dams Based on Discrete Crack Method

    Directory of Open Access Journals (Sweden)

    A. R. Lohrasbi

    2008-01-01

    Full Text Available Seepage is the most parameter in water management safety and in stable agricultural. This seepage is passed through the cracks that are present to some degree in hydraulic structures. They may exist as basic defects in the constituent materials or may be induced in construction or during service life. To avoid such failure in concrete dams, safety would be an important factor. Over-design carries heavy penalty in terms of excess weight. So the fracture mechanics theory is a principal necessity of evaluating the stability of such crack propagation. For the process of crack propagation analysis in concrete structures, there are two general models: discrete crack and smeared crack. This study surveys the crack propagation in concrete gravity dams based on discrete crack methods. Moreover, we use a program provided specifically for this purpose.

  12. General forms of elastic-plastic matching equations for mode-Ⅲ cracks near crack line

    Institute of Scientific and Technical Information of China (English)

    Zhi-jian YI; Chao-hua ZHAO; Qing-guo YANG; Kai PENG; Zong-ming HUANG

    2009-01-01

    Crack line analysis is an effective way to solve elastic-plastic crack problems.Application of the method does not need the traditional small-scale yielding conditions and can obtain sufficiently accurate solutions near the crack line. To address mode-Ⅲ crack problems under the perfect elastic-plastic condition,matching procedures of the crack line analysis method are summarized and refined to give general forms and formulation steps of plastic field,elastic-plastic boundary,and elastic-plastic matching equations near the crack line. The research unifies mode-Ⅲ crack problems under different conditions into a problem of determining four integral constants with four matching equations.An example is given to verify correctness,conciseness,and generality of the procedure.

  13. Process analysis of syngas production by non-catalytic POX of oven gas

    Institute of Scientific and Technical Information of China (English)

    Fuchen WANG; Xinwen ZHOU; Wenyuan GUO; Zhenghua DAI; Xin GONG; Haifeng LIU; Guangsuo YU; Zunhong YU

    2009-01-01

    A non-catalytic POX of oven gas is proposed to solve the problem of secondary pollution due to solid wastes produced from the great amount of organic sulfur contained in oven gas in the traditional catalytic partial oxidation (POX) process. A study of the measurement of flow field and a thermodynamic analysis of the process characteristics were conducted. Results show that there exist a jet-flow region, a recirculation-flow region, a tube-flow region, and three corresponding reaction zones in the non-catalytic POX reformer. The combustion of oven gas occurs mainly in the jet-flow region, while the reformation of oven gas occurs mainly in the other two regions. Soot would not be formed by CH4 cracking at above 1200℃. Since there are very little C2+ hydrocarbons in oven gas, the soot produced would be very tiny, even if they underwent cracking reaction. The integrated model for entrained bed gasification process was applied to simulate a non-catalytic POX reformer. It indicated that the proper oxygen-to-oven gas ratio is 0.22-0.28 at differ-ent pressures in the oven gas reformation process.

  14. Investigating Reaction-Driven Cracking

    Science.gov (United States)

    Kelemen, P. B.; Hirth, G.; Savage, H. M.

    2013-12-01

    Many metamorphic reactions lead to large volume changes, and potentially to reaction-driven cracking [1,2]. Large-scale hydration of mantle peridotite to produce serpentine or talc is invoked to explain the rheology of plate boundaries, the nature of earthquakes, and the seismic properties of slow-spread ocean crust and the 'mantle wedge' above subduction zones. Carbonation of peridotite may be an important sink in the global carbon cycle. Zones of 100% magnesite + quartz replacing peridotite, up to 200 m thick, formed where oceanic mantle was thrust over carbonate-bearing metasediments in Oman. Talc + carbonate is an important component of the matrix in subduction mélanges at Santa Catalina Island , California, and the Sanbagawa metamorphic belt, Japan. Engineered systems to emulate natural mineral carbonation could provide relatively inexpensive CO2 capture and storage [3]. More generally, engineered reaction-driven cracking could supplement or replace hydraulic fracture in geothermal systems, solution mining, and extraction of tight oil and gas. The controls on reaction-driven cracking are poorly understood. Hydration and carbonation reactions can be self-limiting, since they potentially reduce permeability and armor reactive surfaces [4]. Also, in some cases, hydration or carbonation may take place at constant volume. Small changes in volume due to precipitation of solid products increases stress, destabilizing solid reactants, until precipitation and dissolution rates become equal at a steady state stress [5]. In a third case, volume change due to precipitation of solid products causes brittle failure. This has been invoked on qualitative grounds to explain, e.g., complete serpentinization of mantle peridotite [6]. Below ~ 300°C, the available potential energy for hydration and carbonation of olivine could produce stresses of 100's of MPa [2], sufficient to fracture rocks to 10 km depth or more, causing brittle failure below the steady state stress required

  15. Cracks assessment using ultrasonic technology

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Maria Pia; Tomasella, Marcelo [OLDELVAL S.A. Oleoductos del Valle, Rio Negro (Argentina). Pipeline Integrity Dept.

    2005-07-01

    The goal of Oldelval Integrity Program is to prevent ruptures and leaks, developing strategies for a better handling of the integrity of our pipelines. In order to achieve it we have studied and modeled each process that involved in the integrity pipeline. Those processes are mainly based on defects reported by an internal inspection tool and supplied with field inspection and monitoring data. Years of evaluation, study and the continuous effort overturned towards a phenomenon that worries to the industry, as it is the SCC. Since 1998 up to 2004 SCC was included in the integrity program with some preventive maintenance programs. The accomplishment of the inspection based on ultrasound tools, is the culmination of years of evaluation and investigations supported by field digs and materials susceptibility. This paper describes Oldelval's results with ultrasonic crack detection tool, and how it can be reliably to detect SCC. (author)

  16. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  17. Catalytic gasification of biomass

    Science.gov (United States)

    Robertus, R. J.; Mudge, L. K.; Sealock, L. J., Jr.; Mitchell, D. H.; Weber, S. L.

    1981-12-01

    Methane and methanol synthesis gas can be produced by steam gasification of biomass in the presence of appropriate catalysts. This concept is to use catalysts in a fluidized bed reactor which is heated indirectly. The objective is to determine the technical and economic feasibility of the concept. Technically the concept has been demonstrated on a 50 lb per hr scale. Potential advantages over conventional processes include: no oxygen plant is needed, little tar is produced so gas and water treatment are simplified, and yields and efficiencies are greater than obtained by conventional gasification. Economic studies for a plant processing 2000 T/per day dry wood show that the cost of methanol from wood by catalytic gasification is competitive with the current price of methanol. Similar studies show the cost of methane from wood is competitive with projected future costs of synthetic natural gas. When the plant capacity is decreased to 200 T per day dry wood, neither product is very attractive in today's market.

  18. HZSM-5 CATALYST FOR CRACKING PALM OIL TO BIODIESEL: A COMPARATIVE STUDY WITH AND WITHOUT PT AND PD IMPREGNATION

    Directory of Open Access Journals (Sweden)

    Agus Budianto

    2014-05-01

    Full Text Available The Needs of healthy environment and green energy poses a great demand for alternative energy. Biofuel is one of the alternative energy products that are environmentally friendly. Biofuel can be made from plant oils, especially palm oil. Cracking of palm oil into biofuel is constrained by the availability of catalysts. Moreover the available catalyst still gives a low yield. This research aims to study the effect of Pt and Pd impregnation into HZSM-5 catalyst on the catalytic properties. Another aim is to obtain the operating conditions of the catalytic cracking process of palm oil into biofuel which gives the highest yield and selectivity, especially for biodiesel and biogasoline fractions. Catalytic cracking process was carried out in a micro fixed bed reactor with diameter of 1 cm and length of 16 cm. The reactor was filled with a catalyst. The results of the study successfully prove that Pt and Pd impregnated into HZSM-5 catalyst can increase the yield and selectivity of biodiesel. Pd and Pt are highly recommended to increase the yield and selectivity of biodiesel.

  19. Investigations of soil cracking and preferential flow in a weighing lysimeter filled with cracking clay soil

    Science.gov (United States)

    Greve, A.; Andersen, M. S.; Acworth, R. I.

    2010-10-01

    SummaryAn improved understanding of deep drainage processes in irrigated cracking soils is needed for sustainable irrigation management. To investigate the effect of crack dynamics and macropore flow on drainage in cracking soils, a series of irrigation experiments was carried out in a weighing lysimeter. Subsurface soil cracks of the initially very dry soil were investigated with a videoscope and changes in the surface expression of cracks in response to irrigation events were monitored by time-lapse photography. A bromide tracer was applied to one irrigation event. Variations in the combined soil and moisture mass and the volume of drainage out of the soil column was logged and the drainage EC and bromide content were determined. No drainage occurred out of the soil column during the first 3 out of 6 irrigation events, even though substantial surface runoff into the cracks occurred and, at least initially, soil cracks provided an uninterrupted flow path through the profile. The breakthrough of the bromide tracer, as well as an initially low EC of the drainage water indicate that preferential flow accounted for a substantial part of the first of the two drainage events, even though the soil cracks were sealed on the surface at the onset of the irrigation causing the drainage. The results show that lateral infiltration of macropore flow into the soil matrix can be substantial and should not be neglected while simulating macropore flow and deep drainage in cracking soils. The results also indicate that soil cracks can remain pathways for preferential flow even after they are closed at the soil surface. The type of water application appears to have an impact on the location of crack formation, with flood irrigation favouring reappearance of cracks at previous crack locations and simulated rainfall resulting in shifting crack locations.

  20. Risk behaviors for sexually transmitted diseases among crack users

    Directory of Open Access Journals (Sweden)

    Rafael Alves Guimarães

    2015-08-01

    Full Text Available AbstractObjectives: to investigate the prevalence and risk behaviors by means of reporting of sexually transmitted diseases among crack users.Method: cross-sectional study carried out with 588 crack users in a referral care unit for the treatment of chemical dependency. Data were collected by means of face-to-face interview and analyzed using Stata statistical software, version 8.0.Results: of the total participants, 154 (26.2%; 95% CI: 22.8-29.9 reported antecedents of sexually transmitted diseases. Ages between 25 and 30 years (RP: 2.1; 95% CI: 1.0-4.0 and over 30 years (RP: 3.8; 95% CI: 2.1-6.8, alcohol consumption (RP: 1.9; 95% CI: 1.1-3.3, antecedents of prostitution (RP: 1.9; 95% CI: 1.3-2.9 and sexual intercourse with person living with human immunodeficiency virus/AIDS (RP: 2.7; 95% CI: 1.8-4.2 were independently associated with reporting of sexually transmitted diseases.Conclusion: the results of this study suggest high risk and vulnerability of crack users for sexually transmitted diseases.

  1. Risk behaviors for sexually transmitted diseases among crack users 1

    Science.gov (United States)

    Guimarães, Rafael Alves; da Silva, Leandro Nascimento; França, Divânia Dias da Silva; Del-Rios, Nativa Helena Alves; Carneiro, Megmar Aparecida dos Santos; Teles, Sheila Araujo

    2015-01-01

    Abstract Objectives: to investigate the prevalence and risk behaviors by means of reporting of sexually transmitted diseases among crack users. Method: cross-sectional study carried out with 588 crack users in a referral care unit for the treatment of chemical dependency. Data were collected by means of face-to-face interview and analyzed using Stata statistical software, version 8.0. Results: of the total participants, 154 (26.2%; 95% CI: 22.8-29.9) reported antecedents of sexually transmitted diseases. Ages between 25 and 30 years (RP: 2.1; 95% CI: 1.0-4.0) and over 30 years (RP: 3.8; 95% CI: 2.1-6.8), alcohol consumption (RP: 1.9; 95% CI: 1.1-3.3), antecedents of prostitution (RP: 1.9; 95% CI: 1.3-2.9) and sexual intercourse with person living with human immunodeficiency virus/AIDS (RP: 2.7; 95% CI: 1.8-4.2) were independently associated with reporting of sexually transmitted diseases. Conclusion: the results of this study suggest high risk and vulnerability of crack users for sexually transmitted diseases. PMID:26444164

  2. Study on biomass catalytic pyrolysis for production of bio-gasoline by on-line FTIR

    Institute of Scientific and Technical Information of China (English)

    Chang Bo Lu; Jian Zhong Yao; Wei Gang Lin; Wen Li Song

    2007-01-01

    The pyrolysis of biomass is a promising way for production of bio-gasoline if the stability and quality problems of the bio-crudeoil can be solved by catalytic cracking and reforming. In this paper, an on-line infrared spectrum was used to study the characteristics of catalytic pyrolysis with the following preliminary results. The removal of C=O of organic acid is more difficult than that of aldehydes and ketones. HUSY/γ-Al2O3 and REY/γ-Al2O3 catalysts exhibited better deoxygenating activities while HZSM-5/γ-Al2O3 catalyst exhibited preferred selectivities for production of iso-alkanes and aromatics. Finally, possible mechanisms of biomass catalytic pyrolysis are discussed as well.

  3. Effect of hierarchical porosity and phosphorus modification on the catalytic properties of zeolite Y

    Science.gov (United States)

    Li, Wenlin; Zheng, Jinyu; Luo, Yibin; Da, Zhijian

    2016-09-01

    The zeolite Y is considered as a leading catalyst for FCC industry. The acidity and porosity modification play important roles in determining the final catalytic properties of zeolite Y. The alkaline treatment of zeolite Y by dealumination and alkaline treatment with NaOH and NaOH&TBPH was investigated. The zeolites were characterized by X-ray diffraction, low-temperature adsorption of nitrogen, transmission electron microscope, NMR, NH3-TPD and IR study of acidity. Accordingly, the hierarchical porosity and acidity property were discussed systematically. Finally, the catalytic performance of the zeolites Y was evaluated in the cracking of 1,3,5-TIPB. It was found that desilication with NaOH&TBPH ensured the more uniform intracrystalline mesoporosity with higher microporosity, while preserving higher B/L ratio and moderate Brønsted acidities resulting in catalysts with the most appropriated acidity and then with better catalytic performance.

  4. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brownian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d=3.

  5. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    洪文明; 王梓坤

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brown-ian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d = 3.

  6. Commercial Practice on Technology for High- Temperature Cracking of C4 Fraction to Increase Propylene Yield

    Institute of Scientific and Technical Information of China (English)

    Yu Darong; Zhang Zhigang

    2003-01-01

    This article refers to the results of small-scale and commercial tests on high-temperature cracking of C4 fraction in FCC unit to increase the propylene yield. The bench tests revealed that the conversion rate of C4 fraction during high-temperature cracking reached 37.38 % and propylene yield was equal to 15.60 % with the conversion rate of C4 olefins equating around 50%. The results of commercial application showed that adoption of the technology for high-temperature cracking of C4 fraction in FCC unit had led to an increase of propylene yield by 2.16 % with no remarkable changes in the yields and properties of other products.

  7. Applied model of through-wall crack of coolant vessels of WWER-type reactors

    International Nuclear Information System (INIS)

    We propose an applied-model of Through-Wall Crack (TWC) for WWER-type units primary vessels. The model allows to simulate the main morphological parameters of real TWC, i.e. length, area of inlet and outlet openings, channel depth and small and large size unevenness of the crack surface. The model can be used for developing and improving the coolant-leak detectors for the primary circuit vessels of WWER-units. Also, it can be used for research of the coolant two-phase leakage phenomenon through narrow cracks/channels and thermo-physical processes in heat-insulation layer of the Main Coolant Piping (MCP) during the leak

  8. Effects of Colloidal Silica Binder on Catalytic Activity and Adhesion of HZSM-5 Coatings for Structured Reactors

    Institute of Scientific and Technical Information of China (English)

    Guozhu Liu; Jinhua Guo; Fanxu Meng; Xiangwen Zhang; Li Wang

    2014-01-01

    HZSM-5 coating using three colloidal silica binders, acidic col oidal silica (ACS), neutral colloidal silica (NCS) and basic col oidal silica (BCS), was prepared to study the effect of binders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n-dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.

  9. Subcritical crack growth in two titanium alloys.

    Science.gov (United States)

    Williams, D. N.

    1973-01-01

    Measurement of subcritical crack growth during static loading of precracked titanium alloys in salt water using samples too thin for plane strain loading to predominate was examined as a method for determining the critical stress intensity for crack propagation in salt water. Significant internal crack growth followed by arrest was found at quite low stress intensities, but crack growth rates were relatively low. Assuming these techniques provided a reliable measurement of the critical stress intensity, the value for annealed Ti-4Al-1.5Mo-0.5V alloy was apparently about 35 ksi-in. to the 1/2 power, while that for annealed Ti-4Al-3Mo-1V was below 45 ksi-in. to the 1/2 power. Crack growth was also observed in tests conducted in both alloys in an air environment. At 65 ksi-in. to the 1/2 power, the extent of crack growth was greater in air than in salt water. Ti-4Al-3Mo-1V showed arrested crack growth in air at a stress intensity of 45 ksi-in. to the 1/2 power.

  10. Crack detection in a beam with an arbitrary number of transverse cracks using genetic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Khaji, N. [Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Mehrjoo, M. [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2014-03-15

    In this paper, a crack detection approach is presented for detecting depth and location of cracks in beam-like structures. For this purpose, a new beam element with an arbitrary number of embedded transverse edge cracks, in arbitrary positions of beam element with any depth, is derived. The components of the stiffness matrix for the cracked element are computed using the conjugate beam concept and Betti's theorem, and finally represented in closed-form expressions. The proposed beam element is efficiently employed for solving forward problem (i.e., to gain precise natural frequencies and mode shapes of the beam knowing the cracks' characteristics). To validate the proposed element, results obtained by new element are compared with two-dimensional (2D) finite element results and available experimental measurements. Moreover, by knowing the natural frequencies and mode shapes, an inverse problem is established in which the location and depth of cracks are determined. In the inverse approach, an optimization problem based on the new finite element and genetic algorithms (GAs) is solved to search the solution. It is shown that the present algorithm is able to identify various crack configurations in a cracked beam. The proposed approach is verified through a cracked beam containing various cracks with different depths.

  11. Crack growth monitoring at CFRP bond lines

    Science.gov (United States)

    Rahammer, M.; Adebahr, W.; Sachse, R.; Gröninger, S.; Kreutzbruck, M.

    2016-02-01

    With the growing need for lightweight technologies in aerospace and automotive industries, fibre-reinforced plastics, especially carbon-fibre (CFRP), are used with a continuously increasing annual growth rate. A promising joining technique for composites is adhesive bonding. While rivet holes destroy the fibres and cause stress concentration, adhesive bond lines distribute the load evenly. Today bonding is only used in secondary structures due to a lack of knowledge with regard to long-term predictability. In all industries, numerical simulation plays a critical part in the development process of new materials and structures, while it plays a vital role when it comes to CFRP adhesive bondings conducing the predictability of life time and damage tolerance. The critical issue with adhesive bondings is crack growth. In a dynamic tensile stress testing machine we dynamically load bonded CFRP coupon specimen and measure the growth rate of an artificially started crack in order to feed the models with the results. We also investigate the effect of mechanical crack stopping features. For observation of the bond line, we apply two non-contact NDT techniques: Air-coupled ultrasound in slanted transmission mode and active lockin-thermography evaluated at load frequencies. Both methods give promising results for detecting the current crack front location. While the ultrasonic technique provides a slightly higher accuracy, thermography has the advantage of true online monitoring, because the measurements are made while the cyclic load is being applied. The NDT methods are compared to visual inspection of the crack front at the specimen flanks and show high congruence. Furthermore, the effect of crack stopping features within the specimen on the crack growth is investigated. The results show, that not all crack fronts are perfectly horizontal, but all of them eventually come to a halt in the crack stopping feature vicinity.

  12. Chaos caused by fatigue crack growth

    International Nuclear Information System (INIS)

    The nonlinear dynamic responses including chaotic oscillations caused by a fatigue crack growth are presented. Fatigue tests have been conducted on a novel fatigue-testing rig, where the loading is generated from inertial forces. The nonlinearity is in the form of discontinuous stiffness caused by the opening and closing of a growing crack. Nonlinear dynamic tools such as Poincare maps and bifurcation diagrams are used to unveil the global dynamics of the system. The results obtained indicate that fatigue crack growth strongly influences the dynamic response of the system leading to chaos

  13. Chaos caused by fatigue crack growth

    Energy Technology Data Exchange (ETDEWEB)

    Foong, C.-H.; Pavlovskaia, Ekaterina; Wiercigroch, Marian; Deans, William

    2003-06-01

    The nonlinear dynamic responses including chaotic oscillations caused by a fatigue crack growth are presented. Fatigue tests have been conducted on a novel fatigue-testing rig, where the loading is generated from inertial forces. The nonlinearity is in the form of discontinuous stiffness caused by the opening and closing of a growing crack. Nonlinear dynamic tools such as Poincare maps and bifurcation diagrams are used to unveil the global dynamics of the system. The results obtained indicate that fatigue crack growth strongly influences the dynamic response of the system leading to chaos.

  14. Cracks in high-manganese cast steel

    Directory of Open Access Journals (Sweden)

    A. Chojecki

    2009-10-01

    Full Text Available The reasons which account for the formation of in service cracks in castings made from Hadfield steel were discussed. To explain the source of existence of the nuclei of brittle fractures, the properties of cast steel were examined within the range of solidification temperatures, remembering that feeding of this material is specially difficult, causing microporosity in hot spots. This creates conditions promoting the formation of microcracks which tend to propagate during service conditions involving high dynamic stresses, and explains why the cracks are mainly characterized by a brittle nature. The reason for crack formation in service are micro-porosities formed during casting solidification.

  15. Slow crack growth in spinel in water

    Science.gov (United States)

    Schwantes, S.; Elber, W.

    1983-01-01

    Magnesium aluminate spinel was tested in a water environment at room temperature to establish its slow crack-growth behavior. Ring specimens with artificial flaws on the outside surface were loaded hydraulically on the inside surface. The time to failure was measured. Various precracking techniques were evaluated and multiple precracks were used to minimize the scatter in the static fatigue tests. Statistical analysis techniques were developed to determine the strength and crack velocities for a single flaw. Slow crack-growth rupture was observed at stress intensities as low as 70 percent of K sub c. A strengthening effect was observed in specimens that had survived long-time static fatigue tests.

  16. Effect of Concrete Cracks on Dynamic Characteristics of Powerhouse for Giant-Scale Hydrostation

    Institute of Scientific and Technical Information of China (English)

    TIAN Ziain; ZHANG Yunliang; MA Zhenvue; CHEN Jing

    2008-01-01

    With the increase of capacity and size of the hydro-generator unit, the spiral case be-comes a more super-giant hydraulic structure with very high hid value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse.Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits.Results in this paper have been verified by practice of Three-Gorge Project.

  17. Interfacial Crack Arrest in Sandwich Panels with Embedded Crack Stoppers Subjected to Fatigue Loading

    Science.gov (United States)

    Martakos, G.; Andreasen, J. H.; Berggreen, C.; Thomsen, O. T.

    2016-08-01

    A novel crack arresting device has been implemented in sandwich panels and tested using a special rig to apply out-of-plane loading on the sandwich panel face-sheets. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect of the embedded crack arresters was evaluated in terms of the achieved enhancement of the damage tolerance of the tested sandwich panels. A finite element (FE) model of the experimental setup was used for predicting propagation rates and direction of the crack growth. The FE simulation was based on the adoption of linear fracture mechanics and a fatigue propagation law (i.e. Paris law) to predict the residual fatigue life-time and behaviour of the test specimens. Finally, a comparison between the experimental results and the numerical simulations was made to validate the numerical predictions as well as the overall performance of the crack arresters.

  18. Catalytic Mechanism of Human Alpha-galactosidase

    Energy Technology Data Exchange (ETDEWEB)

    Guce, A.; Clark, N; Salgado, E; Ivanen, D; Kulinskaya, A; Brumer, H; Garman, S

    2010-01-01

    The enzyme {alpha}-galactosidase ({alpha}-GAL, also known as {alpha}-GAL A; E.C. 3.2.1.22) is responsible for the breakdown of {alpha}-galactosides in the lysosome. Defects in human {alpha}-GAL lead to the development of Fabry disease, a lysosomal storage disorder characterized by the buildup of {alpha}-galactosylated substrates in the tissues. {alpha}-GAL is an active target of clinical research: there are currently two treatment options for Fabry disease, recombinant enzyme replacement therapy (approved in the United States in 2003) and pharmacological chaperone therapy (currently in clinical trials). Previously, we have reported the structure of human {alpha}-GAL, which revealed the overall structure of the enzyme and established the locations of hundreds of mutations that lead to the development of Fabry disease. Here, we describe the catalytic mechanism of the enzyme derived from x-ray crystal structures of each of the four stages of the double displacement reaction mechanism. Use of a difluoro-{alpha}-galactopyranoside allowed trapping of a covalent intermediate. The ensemble of structures reveals distortion of the ligand into a {sup 1}S{sub 3} skew (or twist) boat conformation in the middle of the reaction cycle. The high resolution structures of each step in the catalytic cycle will allow for improved drug design efforts on {alpha}-GAL and other glycoside hydrolase family 27 enzymes by developing ligands that specifically target different states of the catalytic cycle. Additionally, the structures revealed a second ligand-binding site suitable for targeting by novel pharmacological chaperones.

  19. Dynamic Strain and Crack Monitoring Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research proposes to develop a new automated vehicle health monitoring sensor system capable of measuring loads and detecting crack, corrosion, and...

  20. Inner Crack Detection Method for Cantilever Beams

    Science.gov (United States)

    Li, Zheng; Zhang, Wei; Li, Yixuan; Su, Xianyue

    2008-02-01

    In this paper, continuous wavelet transform has been performed to extract the inner crack information from the guided waves in cantilever beams, and the location and size of crack can be detected exactly. Considering its best time-frequency property, Gabor continuous wavelet transform is employed to analyze the complicated flexible wave signals in cantilever beam, which is inspirited by an impact on the free end. Otherwise, in order to enhance the sensitivity of detection for some small cracks, an improved method is discussed. Here, both computational and experimental methods are carried out for comparing the influence of different crack location in beam. Therefore, the method proposed can be expected to expand to a powerful damage detection method in a broad engineering application.

  1. The Effect of Water on Crack Interaction

    Science.gov (United States)

    Gaede, O.; Regenauer-Lieb, K.

    2009-04-01

    While the mechanical coupling between pore fluid and solid phase is relatively well understood, quantitative studies dealing with chemical-mechanical weakening in geological materials are rare. Many classical poroelastic problems can be addressed with the simple law of effective stress. Experimental studies show that the presence of a chemically active fluid can have effects that exceed the predictions of the law of effective stress. These chemical fluid-rock interactions alter the mechanical properties of the solid phase. Especially chemical-mechanical weakening has important ramifications for many areas of applied geosciences ranging from nuclear waste disposal over reservoir enhancement to fault stability. In this study, we model chemically induced changes of the size of the process zone around a crack tip. The knowledge of the process zone size is used to extend existing effective medium approximations of cracked solids. The stress distribution around a crack leads to a chemical potential gradient. This gradient will be a driver for mass diffusion through the solid phase. As an example, mass diffusion is towards the crack tip for a mode I crack. In this case a chemical reaction, that weakens the solid phase, will increase the size of the process zone around the crack tip. We apply our model to the prominent hydrolytic weakening effect observed in the quartz-water system (Griggs and Blacic, 1965). Hydrolytic weakening is generally attributed to water hydrolyzing the strong Si-O bonds of the quartz crystal. The hydrolysis replaces a Si-O-Si bridge with a relatively weak hydrogen bridge between two silanol groups. This enhances dislocation mobility and hence the yield stress is reduced. The plastic process zone around a crack tip is therefore larger in a wet crystal than in a dry crystal. We calculate the size of the process zone by solving this coupled mechanical-chemical problem with the Finite Element code ABAQUS. We consider single crack, collinear crack and

  2. Initiating, growing and cracking of hydrogen blisters

    Institute of Scientific and Technical Information of China (English)

    REN Xuechong; SHAN Guangbin; CHU Wuyang; SU Yanjing; GAO Kewei; QIAO Lijie; JIANG Bo; CHEN Gang; CUI Yinhui

    2005-01-01

    The growing process of a hydrogen blister in a wheel steel was observed in situ with an optical microscope, and the fracture surfaces formed from broken blisters on a wheel steel and bulk metallic glass were investigated. The initiating, growing, cracking and breaking of hydrogen blisters are as follows. Supersaturated vacancies can increase greatly during charging and gather together into a vacancy cluster (small cavity). Hydrogen atoms become hydrogen molecules in the vacancy cluster and hydrogen molecules can stabilize the vacancy cluster. The small cavity becomes the nucleus of hydrogen blister. The blister will grow with entering of vacancies and hydrogen atoms. With increasing hydrogen pressure, plastic deformation occurs first, the hydrogen blister near the surface extrudes, and then cracks initiate along the wall of the blister with further increasing hydrogen pressure. A cracked blister can grow further through propagating of cracks until it breaks.

  3. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  4. Finite Element Analysis of the Effect of Crack Depth and Crack Opening On the Girder

    Directory of Open Access Journals (Sweden)

    Md. Kamrul Hassan

    2011-01-01

    Full Text Available In order to identify the effect of crack depth and opening on the girder, finite element method (FEM has been used in this paper. In FE analysis, six nodded two dimensional plane elements (PLANE-2 are considered. Each node has two degree of freedom such as UX and UY. For the plane elements, a plane stress width/thickness option is chosen. For analytical model of crack of the concrete bridge girder, crack opening was increased from 0.2 mm to 1mm at an interval 0.2 mm and crack depth also increased from 30 mm to 150 mm at an interval 30 mm. The models were discreatized by a triangular mesh and convergence test was executed to obtain satisfactory results from the Plane-2 element. From the numerical result, it is seen that the principal stress become a higher with increased the crack depth and also crack opening with respect to load increasing. But the crack depth at 90 mm and crack opening at 0.6 mm, it has more effect on the girder because the stress concentration is higher than other crack depth and opening.

  5. Thermal fatigue crack growth in stainless steel

    International Nuclear Information System (INIS)

    A judgment of residual service life of engineering parts exposed to thermal fatigue makes it possible to deal with economic and safety issues in power plants. The aim of this study is to analyze a fatigue crack initiation and propagation in A321 stainless steel bodies subjected to repeated thermal shocks. For this purpose, various methods of crack propagation monitoring were used. The first stage of experiments included mechanical cyclic loading of specimens with the central notch at fixed temperatures ranging from 20 °C to 410 °C. The crack growth rate was only minimally influenced by temperature in this case. Thermal loading of the same specimens with ΔT varying from 150 °C to 340 °C showed very rapid crack initiation in the notches and its asymmetric growth. Metallographic and fractographic analyses of failed specimens were carried out after 1000, 3000 and 6000 thermal cycles. The comparison of the fracture surface micromorphology confirmed the similarity in the mechanism of the thermal and mechanical fatigue crack growth. Stress analysis using the finite element method consisting of transient thermal and mechanical solutions was performed in order to simulate the experiments. Thermal fatigue crack growth assessment was carried out on the basis of the experiments and the computed thermally induced stress intensity factors. This model successfully confirms the discussed analogy of thermal and mechanical stress induced damage. Highlights: ► A fatigue crack initiation and propagation in A321 stainless steel was analyzed. ► Mechanical and thermal experiments were performed, simulated also by FEM. ► Similarity in the mechanism of thermal and mechanical fatigue crack growth found. ► Application of the Paris model for the thermal cycling confirmed.

  6. Composite Pressure Vessel Including Crack Arresting Barrier

    Science.gov (United States)

    DeLay, Thomas K. (Inventor)

    2013-01-01

    A pressure vessel includes a ported fitting having an annular flange formed on an end thereof and a tank that envelopes the annular flange. A crack arresting barrier is bonded to and forming a lining of the tank within the outer surface thereof. The crack arresting barrier includes a cured resin having a post-curing ductility rating of at least approximately 60% through the cured resin, and further includes randomly-oriented fibers positioned in and throughout the cured resin.

  7. Next Generation Steam Cracking Reactor Concept

    OpenAIRE

    Van Goethem, M.W.M.

    2010-01-01

    The steam cracking process is an important asset in the hydrocarbon processing industry. The main products are lower olefins and hydrogen, with ethylene being the world's largest volume organic chemical at a worldwide capacity of ~ 120 million tonnes per year. Feed stocks are hydrocarbons such as: ethane, LPG, naphtha's, gas condensates and gas oil. The research goal of this thesis is to search for the intrinsic optimal steam cracking reaction conditions, pushing the olefin yields to the maxi...

  8. Crack tip stress fields under complex loads

    International Nuclear Information System (INIS)

    The author and his assocates have worked towards the development of an experimental method for estimating SIF distributions in 3D cracked body problems where neither SIF distribution nor flaw shape were known a-priori. The method consists of a marriage between the 'frozen stress' photoelastic method and the near field equations of linear elastic fracture mechanics. Originally proposed for Mode I measurements only, the method has since been refined and extended to mixed mode problems. Comparisons of the method with results from fatigue crack growth studies on reactor steels suggest that flaw shapes generated in the photoelastic models under Mode I loading closely reproduce those in the steel models under certain conditions. The method has since been applied to a variety of complex 3D cracked body problems. The paper describes the results obtained from applying the method to two basic problem classes: i) Part circular 'artificial' (machined) surface flaws in uniaxially loaded flat plates inclined at an angle to the plate surface from the applied load direction. This produced all three local modes of deformation near the flaw border. ii) Natural nozzle corner cracks inclined at an angle to the axis of the reactor vessel. Initially these cracks were planar and exhibited Mode I loading near the nozzle wall and mixed mode loading near the vessel wall. Upon initiation of stable flaw growth under internal pressure above critical temperature, the portion of the crack near the nozzle wall remained in its plane and retained its Mode I character. However, that portion of the crack under mixed mode loading immediately reoriented itself to eliminate the shear modes, producing a non-planar flaw under pure Mode I loading. Results suggest that stable growing cracks in isotropic materials do not exhibit shear modes. (orig./HP)

  9. Protection of brittle film against cracking

    Science.gov (United States)

    Musil, J.; Sklenka, J.; Čerstvý, R.

    2016-05-01

    This article reports on the protection of the brittle Zrsbnd Sisbnd O film against cracking in bending by the highly elastic top film (over-layer). In experiments the Zrsbnd Sisbnd O films with different elemental composition and structure were used. Both the brittle and highly elastic films were prepared by magnetron sputtering using a dual magnetron. The brittle film easily cracks in bending. On the other hand, the highly elastic film exhibits enhanced resistance to cracking in bending. Main characteristic parameters of both the brittle and highly elastic films are given. Special attention is devoted to the effect of the structure (crystalline, amorphous) of both the brittle and highly elastic top film on the resistance of cracking of the brittle film. It was found that (1) both the X-ray amorphous and crystalline brittle films easily crack in bending, (2) the highly elastic film can have either X-ray amorphous or crystalline structure and (3) both the X-ray amorphous and crystalline, highly elastic top films perfectly protect the brittle films against cracking in bending. The structure, mechanical properties and optical transparency of the brittle and highly elastic sputtered Zrsbnd Sisbnd O films are described in detail. At the end of this article, the principle of the low-temperature formation of the highly elastic films is also explained.

  10. Axial crack propagation and arrest in pressurized fuselage

    Science.gov (United States)

    Kosai, M.; Shimamoto, A.; Yu, C.-T.; Walker, S. I.; Kobayashi, A. S.; Tan, P.

    1994-01-01

    The crack arrest capability of a tear strap in a pressurized precracked fuselage was studied through instrumented axial rupture tests of small scale models of an idealized fuselage. Upon pressurization, rapid crack propagation initiated at an axial through crack along the stringer and immediately kinked due to the mixed modes 1 and 2 state caused by the one-sided opening of the crack flap. The diagonally running crack further turned at the tear straps. Dynamic finite element analysis of the rupturing cylinder showed that the crack kinked and also ran straight in the presence of a mixed mode state according to a modified two-parameter crack kinking criterion.

  11. Extended FEM modeling of crack paths near inclusions

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Legarth, Brian Nyvang; Niordson, Christian Frithiof

    2012-01-01

    the effects on the crack path when changing the relative stiffness between inclusion and matrix material, the relative distance between initial crack and inclusion, and the size of the inclusion. Both edge cracks and internal cracks are studied. An example with an internal crack near an inclusion is presented......The extended FEM is applied to model crack growth near inclusions. A procedure to handle different propagation rates at different crack tips is presented. The examples considered investigate uniform tension as well as equibiaxial tension under plane strain conditions. A parameter study analyzes...

  12. Crack shape analysis of PWSCC in S/G tubings

    Energy Technology Data Exchange (ETDEWEB)

    Park, I. K. [Sunmon Univ., Chonan (Korea, Republic of)

    2000-10-01

    Crack shape of PWSCC was analyzed, based on the fractured pulled-out S/G tubings of Ulchin-1 steam generator. The shape of the cracks in kiss roll transitions was elliptical shape for short cracks, and car shape for long cracks with flat crack front. The bulging was observed under the inner wall after shot-peening. Crack shape change after shot-peening was resulted from the crack growth restraint in axial direction due to compressive residual stresses on the primary side surface.

  13. Physical and Numerical Simulation for Inner Crack Healing in Metals

    Institute of Scientific and Technical Information of China (English)

    Jingtao HAN; Dongbin WEI; Yongjun ZHANG

    2004-01-01

    The research purpose on the healing of inner crack in metallic materials is to provide an effective approach for improving their properties and prolonging their lifetime. The crack healing process of 20MnMo steel with inner pre-crack was analyzed. It was found that all inner cracks could be healed in different degree. There were very fine ferrite grains in healing region. The micro-crack healing process in single crystal of BBC-Fe was simulated by the molecule dynamics method, which showed that the critical temperature of crack healing in BBC-Fe is 673K. There were micro-voids, dislocations and twins left after crack healing.

  14. Thermally activated processes of fatigue crack growth in steels

    Science.gov (United States)

    Tanaka, Masaki; Fujii, Atsushi; Noguchi, Hiroshi; Higashida, Kenji

    2014-02-01

    Fatigue crack growth rates in steels at high and low temperatures have been investigated using Paris curves. The fatigue crack growth rates at high temperatures are quite different from those at low temperatures. Arrhenius plots between fatigue crack growth rate (da/dN) and test temperatures at constant stress intensity factor range (ΔKI) indicate a difference of the rate-controlling process for fatigue crack growth with temperature. Slip deformation at the crack tip governs fatigue crack growth at high temperatures, while hydrogen diffusion is associated with crack growth at low temperatures.

  15. Finite element microscopic stress analysis of cracked composite systems

    Science.gov (United States)

    Ko, W. L.

    1978-01-01

    This paper considers the stress concentration problems of two types of cracked composite systems: (1) a composite system with a broken fiber (a penny-shaped crack problem), and (2) a composite system with a cracked matrix (an annular crack problem). The cracked composite systems are modeled with triangular and trapezoidal ring finite elements. Using NASTRAN (NASA Structural Analysis) finite element computer program, the stress and deformation fields in the cracked composite systems are calculated. The effect of fiber-matrix material combination on the stress concentrations and on the crack opening displacements is studied.

  16. Catalytic coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Weller, S W

    1981-01-01

    Monolith catalysts of MoO/sub 3/-CoO-Al/sub 2/O/sub 3/ were prepared and tested for coal liquefaction in a stirred autoclave. In general, the monolith catalysts were not as good as particulate catalysts prepared on Corning alumina supports. Measurement of O/sub 2/ chemisorption and BET surface area has been made on a series of Co/Mo/Al/sub 2/O/sub 3/ catalysts obtained from PETC. The catalysts were derived from Cyanamid 1442A and had been tested for coal liquefaction in batch autoclaves and continuous flow units. MoO/sub 3/-Al/sub 2/O/sub 3/ catalysts over the loading range 3.9 to 14.9 wt % MoO/sub 3/ have been studied with respect to BET surface (before and after reduction), O/sub 2/ chemisorption at -78/sup 0/C, redox behavior at 500/sup 0/C, and activity for cyclohexane dehydrogenation at 500/sup 0/C. In connection with the fate of tin catalysts during coal liquefaction, calculations have been made of the relative thermodynamic stability of SnCl/sub 2/, Sn, SnO/sub 2/, and SnS in the presence of H/sub 2/, HCl, H/sub 2/S and H/sub 2/O. Ferrous sulfate dispersed in methylnaphthalene has been shown to be reduced to ferrous sulfide under typical coal hydroliquefaction conditions (1 hour, 450/sup 0/C, 1000 psi initial p/sub H/sub 2//). This suggests that ferrous sulfide may be the common catalytic ingredient when either (a) ferrous sulfate impregnated on powdered coal, or (b) finely divided iron pyrite is used as the catalyst. Old research on impregnated ferrous sulfate, impregnated ferrous halides, and pyrite is consistent with this assumption. Eight Co/Mo/Al/sub 2/O/sub 3/ catalysts from commercial suppliers, along with SnCl/sub 2/, have been studied for the hydrotreating of 1-methylnaphthalene (1-MN) in a stirred autoclave at 450 and 500/sup 0/C.

  17. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation

    Directory of Open Access Journals (Sweden)

    Achmad Roesyadi

    2013-03-01

    Full Text Available It is important to develop a renewable source of energy to overcome a limited source fossil energy. Palm oil is a potential alternative and environmental friendly energy resource in Indonesia due to high production capacity of this vegetable oil. The research studied effect of catalyst to selectivity of biofuel product from cracking of palm oil. The catalyst consisted of HZSM-5 catalyst with or without impregnation. The research was conducted in two steps, namely catalyst synthesized and catalytic cracking process. HZSM-5 was synthesized using Plank methods. The characterization of the synthesized catalysts used AAS (Atomic Absorption Spectroscopy and BET (Brunaueur Emmet Teller. The cracking was carried out in a fixed bed microreactor with diameter of 1 cm and length of 16 cm which was filled with 0.6 gram catalyst. The Zn/HZSM-5 catalyst was recommended for cracking palm oil for the high selectivity to gasoline. © 2013 BCREC UNDIP. All rights reserved.(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 28th September 2012; Revised: 19th November 2012; Accepted: 20th December 2012[How to Cite: A. Roesyadi, D. Hariprajitno, N. Nurjannah, S.D. Savitri, (2013. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 185-190.(doi:10.9767/bcrec.7.3.4045.185-190][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4045.185-190 ] View in  |

  18. Catalytic distillation water recovery subsystem

    Science.gov (United States)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  19. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.

  20. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne;

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  1. Hierarchical Formation of Intrasplat Cracks in Thermal Spray Ceramic Coatings

    Science.gov (United States)

    Chen, Lin; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2016-06-01

    Intrasplat cracks, an essential feature of thermally sprayed ceramic coatings, play important roles in determining coating properties. However, final intrasplat crack patterns are always considered to be disordered and irregular, resulting from random cracking during splat cooling, since the detailed formation process of intrasplat cracks has scarcely been considered. In the present study, the primary formation mechanism for intrasplat cracking was explored based on both experimental observations and mechanical analysis. The results show that the intrasplat crack pattern in thermally sprayed ceramic splats presents a hierarchical structure with four sides and six neighbors, indicating that intrasplat crack patterns arise from successive domain divisions due to sequential cracking during splat cooling. The driving forces for intrasplat cracking are discussed, and the experimental data quantitatively agree well with theoretical results. This will provide insight for further coating structure designs and tailoring by tuning of intrasplat cracks.

  2. Analysis of internal crack healing mechanism under rolling deformation.

    Science.gov (United States)

    Gao, Haitao; Ai, Zhengrong; Yu, Hailiang; Wu, Hongyan; Liu, Xianghua

    2014-01-01

    A new experimental method, called the 'hole filling method', is proposed to simulate the healing of internal cracks in rolled workpieces. Based on the experimental results, the evolution in the microstructure, in terms of diffusion, nucleation and recrystallisation were used to analyze the crack healing mechanism. We also validated the phenomenon of segmented healing. Internal crack healing involves plastic deformation, heat transfer and an increase in the free energy introduced by the cracks. It is proposed that internal cracks heal better under high plastic deformation followed by slow cooling after rolling. Crack healing is controlled by diffusion of atoms from the matrix to the crack surface, and also by the nucleation and growth of ferrite grain on the crack surface. The diffusion mechanism is used to explain the source of material needed for crack healing. The recrystallisation mechanism is used to explain grain nucleation and growth, accompanied by atomic migration to the crack surface. PMID:25003518

  3. Stress corrosion cracking of copper canisters

    Energy Technology Data Exchange (ETDEWEB)

    King, Fraser (Integrity Corrosion Consulting Limited (Canada)); Newman, Roger (Univ. of Toronto (Canada))

    2010-12-15

    A critical review is presented of the possibility of stress corrosion cracking (SCC) of copper canisters in a deep geological repository in the Fennoscandian Shield. Each of the four main mechanisms proposed for the SCC of pure copper are reviewed and the required conditions for cracking compared with the expected environmental and mechanical loading conditions within the repository. Other possible mechanisms are also considered, as are recent studies specifically directed towards the SCC of copper canisters. The aim of the review is to determine if and when during the evolution of the repository environment copper canisters might be susceptible to SCC. Mechanisms that require a degree of oxidation or dissolution are only possible whilst oxidant is present in the repository and then only if other environmental and mechanical loading conditions are satisfied. These constraints are found to limit the period during which the canisters could be susceptible to cracking via film rupture (slip dissolution) or tarnish rupture mechanisms to the first few years after deposition of the canisters, at which time there will be insufficient SCC agent (ammonia, acetate, or nitrite) to support cracking. During the anaerobic phase, the supply of sulphide ions to the free surface will be transport limited by diffusion through the highly compacted bentonite. Therefore, no HS. will enter the crack and cracking by either of these mechanisms during the long term anaerobic phase is not feasible. Cracking via the film-induced cleavage mechanism requires a surface film of specific properties, most often associated with a nano porous structure. Slow rates of dissolution characteristic of processes in the repository will tend to coarsen any nano porous layer. Under some circumstances, a cuprous oxide film could support film-induced cleavage, but there is no evidence that this mechanism would operate in the presence of sulphide during the long-term anaerobic period because copper sulphide

  4. 催化裂解制低碳烯烃技术研究进展%Research Advances in Light Olefine by Catalytic Pyrolysis

    Institute of Scientific and Technical Information of China (English)

    马新龙; 张萍; 高道伟

    2012-01-01

    The rapid development trend of China ethylene industry in the recent years was introduced. Most of the light olefine were produced by the steam cracking in the worldwide. The steam cracking technology was extremely limited by the growing heavy low - quality and inferior quality trends of crude oil. Recent domestic and foreign catalytic pyrolysis technologies of the feedstock at the range of light hydrocarbon to heavy oil were reviewed. The representative technologies of deep catalytic cracking, catalytic pyrolysis process and heavy - oil contact cracking were introduced with emphasis. Heavy oil catalytic cracking was more suitable to our national condition. As of novel and effective catalyst matching with the technologies, the relationship between catalyst acid strength, nent and the catalytic pyrolysis activity was found out, which laid alytic pyrolysis technologies. pore distribution, the content of metal and active compo- a firmer foundation for the overall industrialization of cat-%综述了目前国内外以轻烃到重油范围内为原料的催化裂解工艺技术,着重介绍了我国有代表性的研究成果DCC、CPP及HCC工艺。而重油催化裂解更适合于我国国情,并指出在研制与工艺技术相匹配的高效新型催化剂方面,找到催化剂酸强度、孔道分布、金属含量和活性组分含量与催化裂解活性之间的关系,为催化裂解制低碳烯烃工艺技术能够全面实行工业化奠定更坚实的基础。

  5. Biogenic Cracks in Porous Rock

    Science.gov (United States)

    Hemmerle, A.; Hartung, J.; Hallatschek, O.; Goehring, L.; Herminghaus, S.

    2014-12-01

    Microorganisms growing on and inside porous rock may fracture it by various processes. Some of the mechanisms of biofouling and bioweathering are today identified and partially understood but most emphasis is on chemical weathering, while mechanical contributions have been neglected. However, as demonstrated by the perseverance of a seed germinating and cracking up a concrete block, the turgor pressure of living organisms can be very significant. Here, we present results of a systematic study of the effects of the mechanical forces of growing microbial populations on the weathering of porous media. We designed a model porous medium made of glass beads held together by polydimethylsiloxane (PDMS), a curable polymer. The rheological properties of the porous medium, whose shape and size are tunable, can be controlled by the ratio of crosslinker to base used in the PDMS (see Fig. 1). Glass and PDMS being inert to most chemicals, we are able to focus on the mechanical processes of biodeterioration, excluding any chemical weathering. Inspired by recent measurements of the high pressure (~0.5 Mpa) exerted by a growing population of yeasts trapped in a microfluidic device, we show that yeast cells can be cultured homogeneously within porous medium until saturation of the porous space. We investigate then the effects of such an inner pressure on the mechanical properties of the sample. Using the same model system, we study also the complex interplay between biofilms and porous media. We focus in particular on the effects of pore size on the penetration of the biofilm within the porous sample, and on the resulting deformations of the matrix, opening new perspectives into the understanding of life in complex geometry. Figure 1. Left : cell culture growing in a model porous medium. The white spheres represent the grains, bonds are displayed in grey, and microbes in green. Right: microscopy picture of glass beads linked by PDMS bridges, scale bar: 100 μm.

  6. Environment-assisted cracking and hot cracking of Ni-base alloy dissimilar metal welds

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, P.; Toivonen, A.; Ehrnsten, U. (VTT Technical Research Centre of Finland, Espoo (Finland)); Haenninen, H.; Brederholm, A. (Aalto Univ. School of Science and Engineering, Faculty of Engineering and Architecture, Espoo (Finland))

    2010-05-15

    Environment-assisted cracking (EAC) susceptibility of dissimilar metal mock-up welds of Alloy 182 and 82 as well as Alloy 152 and 52 were studied with four-point bending specimens in steam doped with hydrogen, chloride, sulfate and fluoride at 400 deg C. The doped steam environment accelerated the crack initiation process and the susceptibility of the studied weld metals to EAC was obtained and ranked. High susceptibility to crack initiation and growth was observed with Alloy 182 and 82 weld metals, while Alloy 152 and 52 weld metals showed high resistance to crack initiation. No extension of the hot cracks was observed in the doped steam test in any of the studied materials. Fractography of the broken Alloy 182 and 82 samples showed both nickel deposition and presence of NiO in addition to the continuous spinel type Cr-rich oxide film on the fracture surface inside the crack. Fracture path was intergranular in all the studied samples. The same dissimilar metal welds were exposed to Varestraint hot cracking tests and their hot cracking susceptibility was also ranked and determined as a function of the amount of strain. The microstructures of the weld metals were fully characterized by optical metallography and a modern FE-SEM/EDS system. Hot cracking susceptibility was related to the solidification mechanism and segregation of Nb, Si, P and Mn in the weld metals. Fractography of the EAC and hot cracks was compared and their characteristic features are demonstrated. Finally, the mechanisms of hot cracking and EAC of nickel-base alloy dissimilar metal welds are identified and discussed. (orig.)

  7. Geochemical study on oil-cracked gases and kerogen-cracked gases (Ⅱ)——Discrimination methods between oil-cracked gases and kerogen-cracked gases

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In the processes of discrimination between oil-cracked gases and kerogen-cracked gases,Behar and Pinzgofer et al.’s results were adopted in the former researches,in which the ratio of C2/C3 is basically a constant while the ratio of C1/C2 gradually increases in the course of primary cracking of kerogen. Otherwise in the course of secondary cracking of oil,the ratio of C2/C3 increases rapidly while C1/C2 keeps relatively stable. Our study on analogue experiment shows that,whether it is oil or kerogen,in its process of gas generating by cracking,the ratios of C2/C3,C1/C2 or C1/C3 will all be increased with the growth of thermal conditions. In comparison,the ratio of C2/C3,which is affected by genetic type to some comparatively less extent,mainly responds to the maturity of gases,while the value of C2/C3 is about 2,and that of C2/iC4 is about 10,and the corresponding value of Ro is about 1.5%―1.6%. The influence of gas source on C2/C3 is less than that of gas maturity,otherwise C1/C2(or C1/C3) is obviously affected by cracking matrices. The ratios of C1/C2,C1/C3 of oil-cracked gases are less than that of kerogen-cracked gases,under the condition that the ratios of C2/C3 are similar in value,so are the value of dryness indexes. There exists wide diffidence between this view and the former discrimination method in theory. The analysis of the spot sample indicates that we can apply the above basic view to dealing efficiently with the problem of the discrimination between oil-cracked gas and kerogen-cracked gas.

  8. Environmentally assisted cracking in light water reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Chung, H. M.; Clark, R. W.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.; Strain, R. V.

    2007-11-06

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from January to December 2002. Topics that have been investigated include: (a) environmental effects on fatigue crack initiation in carbon and low-alloy steels and austenitic stainless steels (SSs), (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs in BWRs, (c) evaluation of causes and mechanisms of irradiation-assisted cracking of austenitic SS in PWRs, and (d) cracking in Ni-alloys and welds. A critical review of the ASME Code fatigue design margins and an assessment of the conservation in the current choice of design margins are presented. The existing fatigue {var_epsilon}-N data have been evaluated to define the effects of key material, loading, and environmental parameters on the fatigue lives of carbon and low-alloy steels and austenitic SSs. Experimental data are presented on the effects of surface roughness on fatigue crack initiation in these materials in air and LWR environments. Crack growth tests were performed in BWR environments on SSs irradiated to 0.9 and 2.0 x 10{sup 21} n x cm{sup -2}. The crack growth rates (CGRs) of the irradiated steels are a factor of {approx}5 higher than the disposition curve proposed in NUREG-0313 for thermally sensitized materials. The CGRs decreased by an order of magnitude in low-dissolved oxygen (DO) environments. Slow-strain-rate tensile (SSRT) tests were conducted in high-purity 289 C water on steels irradiated to {approx}3 dpa. The bulk S content correlated well with the susceptibility to intergranular SCC in 289 C water. The IASCC susceptibility of SSs that contain >0.003 wt. % S increased drastically. bend tests in inert environments at 23 C were conducted on broken pieces of SSRT specimens and on unirradiated specimens of the same materials after hydrogen charging. The results of the tests and a review of other data in the literature

  9. Catalytic pyrolysis of cellulose in ionic liquid [bmim]OTf.

    Science.gov (United States)

    Qu, Guangfei; He, Weiwei; Cai, Yingying; Huang, Xi; Ning, Ping

    2016-09-01

    This study discussed the catalytic cracking process of cellulose in ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim]OTF) under 180°C, 240°C and 340°C, found that [bmim]OTF is an effective catalyst which can effectively reduce the pyrolysis temperature(nearly 200°C) of the cellulose. FRIR, XRD and SEM were used to analyze the structure characterization of fiber before and after the cracking; GC-MS was used for liquid phase products analysis; GC was used to analyze gas phase products. The results showed that the cellulose pyrolysis in [bmim]OTf mainly generated CO2, CO and H2, also generated 2-furfuryl alcohol, 2,5-dimethyl-1,5-diallyl-3-alcohol, 1,4-butyrolactone, 5-methyl furfural, 4-hydroxy butyric acid, vinyl propionate, 1-acetoxyl group-2-butanone, furan formate tetrahydrofuran methyl ester liquid product, and thus simulated the evolution mechanism of cellulose pyrolysis products based on the basic model of cellulose monomer. PMID:27185153

  10. Stochastic modeling of crack initiation and short-crack growth under creep and creep-fatigue conditions

    Science.gov (United States)

    Kitamura, Takayuki; Ghosn, Louis J.; Ohtani, Ryuichi

    1992-01-01

    A simplified stochastic model is proposed for crack initiation and short-crack growth under creep and creep-fatigue conditions. Material inhomogeneity provides the random nature of crack initiation and early growth. In the model, the influence of microstructure is introduced by the variability of: (1) damage accumulation along grain boundaries, (2) critical damage required for crack initiation or growth, and (3) the grain-boundary length. The probabilities of crack initiation and growth are derived by using convolution integrals. The model is calibrated and used to predict the crack density and crack-growth rate of short cracks of 304 stainless steel under creep and creep-fatigue conditions. The mean-crack initiation lives are predicted to be within an average deviation of about 10 percent from the experimental results. The predicted comulative distributions of crack-growth rate follow the experimental data closely. The applicability of the simplified stochastic model is discussed and the future research direction is outlined.

  11. Evaluation method of cracking resistance of lightweight aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    季韬; 张彬彬; 陈永波; 庄一舟

    2014-01-01

    The cracking behavior of lightweight aggregate concrete (LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete (NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.

  12. Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao; ZHANG Yong-Xin; DU Da-Ming; HUA Wen-Ting

    2003-01-01

    @@ The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.

  13. ENDOFEM INTEGRATED METHODOLOGY FOR FATIGUE CRACK GROWTH

    Institute of Scientific and Technical Information of China (English)

    C.F.Lee; L.T.Hsiao

    2002-01-01

    In this paper, the FEM with the incremental endochronic cyclic plasticity (EndoFEM) and the rc controlled node-released strategy are employed to study the fatigue crack opened/closed load (Pop) of A1 2024-T3 CCT specimens provided by Mageed and Pandey under several crack lengths and the constant amplitude with various load ratio (R). After statisfactory results are achieved by comparisons of computed Pop values and cited experimental data, the simulations will be extended to the crack lengths with significant bending effect due to short ligaments or high peak (Pmax) or high positive or very low negative R cyclic loads. Through these simulations, the complete map of Pop/Pmax vs. Kmax and R can be constructed and thereafter its correspondant empirical formulae can be proposed. Using these formulae and selecting the traditional fatigue crack growth parameter ΔKeff, the A1 2024-T3 fatigue crack growth rate da/dN vs. ΔK and R data, provided by Hiroshi and Schijve, can be employed to proposed empirical formulae of da/dN vs. ΔKeff and R. After integration, fatigue-crack-growth length a vs. N curves computed by EndoFEM can be obtained. The results are agreed very well with the existing experimental curves. According to the above procedures of simulation and steps of comparions with experiment, this paper may provides an integrate methodology of numerical simulation in the studies of fatigue crack growth for academic and industrial researches and design analysis.

  14. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.

    2012-05-11

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  15. Crack propagation modeling using Peridynamic theory

    Science.gov (United States)

    Hafezi, M. H.; Alebrahim, R.; Kundu, T.

    2016-04-01

    Crack propagation and branching are modeled using nonlocal peridynamic theory. One major advantage of this nonlocal theory based analysis tool is the unifying approach towards material behavior modeling - irrespective of whether the crack is formed in the material or not. No separate damage law is needed for crack initiation and propagation. This theory overcomes the weaknesses of existing continuum mechanics based numerical tools (e.g. FEM, XFEM etc.) for identifying fracture modes and does not require any simplifying assumptions. Cracks grow autonomously and not necessarily along a prescribed path. However, in some special situations such as in case of ductile fracture, the damage evolution and failure depend on parameters characterizing the local stress state instead of peridynamic damage modeling technique developed for brittle fracture. For brittle fracture modeling the bond is simply broken when the failure criterion is satisfied. This simulation helps us to design more reliable modeling tool for crack propagation and branching in both brittle and ductile materials. Peridynamic analysis has been found to be very demanding computationally, particularly for real-world structures (e.g. vehicles, aircrafts, etc.). It also requires a very expensive visualization process. The goal of this paper is to bring awareness to researchers the impact of this cutting-edge simulation tool for a better understanding of the cracked material response. A computer code has been developed to implement the peridynamic theory based modeling tool for two-dimensional analysis. A good agreement between our predictions and previously published results is observed. Some interesting new results that have not been reported earlier by others are also obtained and presented in this paper. The final objective of this investigation is to increase the mechanics knowledge of self-similar and self-affine cracks.

  16. Recent evaluations of crack-opening-area in circumferentially cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, S.; Brust, F.; Ghadiali, N.; Wilkowski, G.; Miura, N.

    1997-04-01

    Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.

  17. Detection of stress corrosion cracks in reactor pressure vessel and primary coolant system anchor studs

    International Nuclear Information System (INIS)

    This chapter describes a new technique for the detection of cracks in long studs without heater holes. The cylindrically guided wave technique (CGWT) can be used for the detection of small cracks occurring at the far end of long studs and corrosion wastage along the length of the studs. The CGWT is based on the fact that an ultrasonic wave traveling in a long cylinder becomes guided by the geometry of the cylinder. Two conventional techniques used in nuclear power plants to inspect studs with heater holes are discussed. It is determined that for short studs with relatively large critical crack sizes, conventional 0-degree longitudinal inspection is adequate. For long studs with heater holes, the shear wave angle beam inspection technique in which the search unit is inserted into the heater hole is adequate. The CGWT should be used for flaws smaller than critical size located at the end of these studs

  18. Extended displacement discontinuity boundary integral equation and boundary element method for cracks in thermo-magneto-electro-elastic media

    Science.gov (United States)

    Li, Yuan; Dang, HuaYang; Xu, GuangTao; Fan, CuiYing; Zhao, MingHao

    2016-08-01

    The extended displacement discontinuity boundary integral equation (EDDBIE) and boundary element method is developed for the analysis of planar cracks of arbitrary shape in the isotropic plane of three-dimensional (3D) transversely isotropic thermo-magneto-electro-elastic (TMEE) media. The extended displacement discontinuities (EDDs) include conventional displacement discontinuity, electric potential discontinuity, magnetic potential discontinuity, as well as temperature discontinuity across crack faces; correspondingly, the extended stresses represent conventional stress, electric displacement, magnetic induction and heat flux. Employing a Hankel transformation, the fundamental solutions for unit point EDDs in 3D transversely isotropic TMEE media are derived. The EDDBIEs for a planar crack of arbitrary shape in the isotropic plane of a 3D transversely isotropic TMEE medium are then established. Using the boundary integral equation method, the singularities of near-crack border fields are obtained and the extended stress field intensity factors are expressed in terms of the EDDs on crack faces. According to the analogy between the EDDBIEs for an isotropic thermoelastic material and TMEE medium, an analogical solution method for crack problems of a TMEE medium is proposed for coupled multi-field loadings. Employing constant triangular elements, the EDDBIEs are discretized and numerically solved. As an application, the problems of an elliptical crack subjected to combined mechanical-electric-magnetic-thermal loadings are investigated.

  19. OPERATING SPECIFICATIONS OF CATALYTIC CLEANING OF GAS FROM BIOMASS GASIFICATION

    Directory of Open Access Journals (Sweden)

    Martin Lisý

    2015-12-01

    Full Text Available The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e., tar in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate from Horní Lánov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5%, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/mn3. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.

  20. Catalytic properties of niobium compounds

    International Nuclear Information System (INIS)

    The catalytic activity and selectivity of niobium compounds including oxides, salts, organometallic compounds and others are outlined. The application of these compounds as catalysts to diversified reactions is reported. The nature and action of niobium catalysts are characteristic and sometimes anomalous, suggesting the necessity of basic research and the potential use as catalysts for important processes in the chemical industry. (Author)

  1. Simple, chemoselective, catalytic olefin isomerization.

    Science.gov (United States)

    Crossley, Steven W M; Barabé, Francis; Shenvi, Ryan A

    2014-12-01

    Catalytic amounts of Co(Sal(tBu,tBu))Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.

  2. VALIDATION OF CRACK INTERACTION LIMIT MODEL FOR PARALLEL EDGE CRACKS USING TWO-DIMENSIONAL FINITE ELEMENT ANALYSIS

    Directory of Open Access Journals (Sweden)

    R. Daud

    2013-06-01

    Full Text Available Shielding interaction effects of two parallel edge cracks in finite thickness plates subjected to remote tension load is analyzed using a developed finite element analysis program. In the present study, the crack interaction limit is evaluated based on the fitness of service (FFS code, and focus is given to the weak crack interaction region as the crack interval exceeds the length of cracks (b > a. Crack interaction factors are evaluated based on stress intensity factors (SIFs for Mode I SIFs using a displacement extrapolation technique. Parametric studies involved a wide range of crack-to-width (0.05 ≤ a/W ≤ 0.5 and crack interval ratios (b/a > 1. For validation, crack interaction factors are compared with single edge crack SIFs as a state of zero interaction. Within the considered range of parameters, the proposed numerical evaluation used to predict the crack interaction factor reduces the error of existing analytical solution from 1.92% to 0.97% at higher a/W. In reference to FFS codes, the small discrepancy in the prediction of the crack interaction factor validates the reliability of the numerical model to predict crack interaction limits under shielding interaction effects. In conclusion, the numerical model gave a successful prediction in estimating the crack interaction limit, which can be used as a reference for the shielding orientation of other cracks.

  3. Sizing cracks in thin-walled CANDU reactor pressure tubes using crack-tip diffraction

    International Nuclear Information System (INIS)

    The most practical nondestructive means of measuring the depth of cracks approximately 0.4 mm deep in CANDU reactor pressure tubes is the ultrasonic crack-tip diffraction method. Initially, optimum ultrasonic parameters for wave mode, transducer frequency, main-bang pulse characteristics, incident and diffracted angles were obtained on three fatigue cracks, based on the criteria of maximum signal amplitude and accuracy in determination of crack depth. In addition, three signal processing techniques, auto and cross-correlation, rectification and smoothing and the magnitude of the analytic signal, were used to obtain time measurements. The results of these measurements are presented. Except for the first fatigue crack, the depth calculations were accurate to within the specified range of ± 0.1 mm

  4. Evaluation of Stress Intensity Factors for Multiple Cracked Circular Disks Under Crack Surface Tractions with SBFEM

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-yu; LIN Gao; LI Xiao-chuan; XU Feng-lin

    2013-01-01

    Stress intensity factors (SIFs) for the cracked circular disks under different distributing surface tractions are evaluated with the scaled boundary finite element method (SBFEM).In the SBFEM,the analytical advantage of the solution in the radial direction allows SIFs to be directly determined from its definition,therefore no special crack-tip treatment is necessary.Furthermore anisotropic material behavior can be treated easily.Different distributions of surface tractions are considered for the center and double-edge-cracked disks.The benchmark examples are modeled and an excellent agreement between the results in the present study and those in published literature is found.It shows that SBFEM is effective and possesses high accuracy.The SIFs of the cracked orthotropic material circular disks subjected to different surface tractions are also evaluated.The technique of substructure is applied to handle the multiple cracks problem.

  5. Crack injection in silver gold alloys

    Science.gov (United States)

    Chen, Xiying

    Stress corrosion cracking (SCC) is a materials degradation phenomena resulting from a combination of stress and a corrosive environment. Among the alphabet soup of proposed mechanism of SCC the most important are film-rupture, film-induced cleavage and hydrogen embrittlement. This work examines various aspects of film-induced cleavage in gold alloys for which the operation of hydrogen embrittlement processes can be strictly ruled out on thermodynamic grounds. This is so because in such alloys SCC occurs under electrochemical conditions within which water is stable to hydrogen gas evolution. The alloy system examined in this work is AgAu since the corrosion processes in this system occur by a dealloying mechanism that results in the formation of nanoporous gold. The physics behind the dealloying process as well as the resulting formation of nanoporous gold is today well understood. Two important aspects of the film-induced cleavage mechanism are examined in this work: dynamic fracture in monolithic nanoporous gold and crack injection. In crack injection there is a finite thickness dealloyed layer formed on a AgAu alloy sample and the question of whether or not a crack that nucleates within this layer can travel for some finite distance into the un-corroded parent phase alloy is addressed. Dynamic fracture tests were performed on single edge-notched monolithic nanoporous gold samples as well as "infinite strip" sample configurations for which the stress intensity remains constant over a significant portion of the crack length. High-speed photography was used to measure the crack velocity. In the dynamic fracture experiments cracks were observed to travel at speeds as large as 270 m/s corresponding to about 68% of the Raleigh wave velocity. Crack injection experiments were performed on single crystal Ag77Au23, polycrystalline Ag72Au28 and pure gold, all of which had thin nanoporous gold layers on the surface of samples. Through-thickness fracture was seen in both the

  6. Impact of severe cracked germanium (111 substrate on aluminum indium gallium phosphate light-emitting-diode’s electro-optical performance

    Directory of Open Access Journals (Sweden)

    Annaniah Luruthudass

    2016-07-01

    Full Text Available Cracked die is a serious failure mode in the Light Emitting Diode (LED industry – affecting LED quality and long-term reliability performance. In this paper an investigation has been carried out to find the correlation between severe cracked germanium (Ge substrate of an aluminum indium gallium phosphate (AlInGaP LED and its electro-optical performance after the Temperature Cycle (TC test. The LED dice were indented at several bond forces using a die bonder. The indented dice were analysed using a Scanning Electron Microscope (SEM. The result showed that severe cracks were observed at 180 gF onward. As the force of indentation increases, crack formation also becomes more severe thus resulting in the chipping of the substrate. The cracked dies were packaged and the TC test was performed. The results did not show any electro-optical failure or degradation, even after a 1000 cycle TC test. Several mechanically cross-sectioned cracked die LEDs, were analysed using SEM and found that no crack reached the active layer. This shows that severely cracked Ge substrate are able to withstand a −40°C/+100°C TC test up to 1000 cycles and LED optical performance is not affected. A small leakage current was observed in all of the cracked die LEDs in comparison to the reference unit. However, this value is smaller than the product specification and is of no concern.

  7. Crack buckling in soft gels under compression

    Institute of Scientific and Technical Information of China (English)

    Rong Long; Chung-Yuen Hui

    2012-01-01

    Recent interest in designing soft gels with high fracture toughness has called for simple and robust methods to test fracture behavior.The conventional method of applying tension to a gel sample suffers from a difficulty of sample gripping.In this paper,we study a possible fracture mechanism of soft gels under uni-axial compression.We show that the surfaces of a pre-existing crack,oriented parallel to the loading axis,can buckle at a critical compressive stress.This buckling instability can open the crack surfaces and create highly concentrated stress fields near the crack tip,which can lead to crack growth.We show that the onset of crack buckling can be deduced by a dimensional argument combined with an analysis to determine the critical compression needed to induce surface instabilities of an elastic half space.The critical compression for buckling was verified for a neoHookean material model using finite element simulations.

  8. Crack detection tools for feeder inspection

    International Nuclear Information System (INIS)

    Since 1998, the Hydro Quebec Research Centre (IREQ), in collaboration with Gentilly-2 (G2), has been working on the development of inspection devices for the feeder tubes of CANDU power plants. After the 14-probe METAR, which is now the standard equipment for thickness measurement of CANDU feeder pipes, IREQ addressed the industry's growing problem of crack detection in feeder bends and in welded areas. This paper presents three tools developed for this purpose: the Cracking Crawler for crack detection in bends, the Orbital bracelet for crack detection in pipe-to-pipe welds and the Grayloc Scanner for crack detection in the grayloc welds. In addition to the robotic development, the ultrasonic (U-T) techniques developed for automated feeder weld inspection will be described. An earlier version of some of these tools was presented at the 6th International Conference on CANDU Maintenance in 2003, while detailed herein is the latest development and the results of their first field trials, up to the licensing and technical transfer. (author)

  9. Flaw Tolerance for Multiple Fatique Cracks

    Energy Technology Data Exchange (ETDEWEB)

    Gosselin, Stephen R.; Simonen, Fredric A.; Carter, R. G.

    2005-07-01

    This paper documents important details of the technical bases for changes to Appendix L. Calculations identified aspect ratios for equivalent single cracks (ESC) between the extremes of a 6:1 ratio and a full circumferential crack that can be used in Appendix L flaw tolerance assessments to account for the initiation, growth, and linking of multiple fatigue cracks. Probabilistic fracture mechanics (PFM) calculations determined ESC aspect ratios that result in the same through-wall crack probability as multiple small cracks (0.02 inch depth) that initiate and coalesce. The computations considered two materials (stainless and low alloy steels), three pipe diameters, five cyclic membrane-to-gradient stress ratios and a wide range of primary loads. Subsequent deterministic calculations identified the ESC aspect ratio for the hypothetical reference flaw depth assumptions in Appendix L. This paper also describes computations that compare the Appendix L flaw tolerance allowable operating period for the ESC models with results obtained when the a single default 6:1 aspect ratio reference flaw.

  10. Imaging Cracks by Laser Excited Thermography

    Science.gov (United States)

    Schlichting, J.; Kervalishvili, G. N.; Maierhofer, Ch.; Kreutzbruck, M.

    2010-02-01

    During the last years active thermography is increasingly used in a number of NDT problems in production and maintenance. In this work we focus on the detection of vertical cracks starting at the surface, which is an important indication of structural failure. By using local thermal excitation it is possible to image anisotropies in the lateral diffusivity by recording the temporal temperature data with an infrared camera. The regional transient behaviour of temperature distribution then can provide quantitative information of the crack parameter. In doing so, we present an advanced technique for the determination of the crack depth. The experimental set-up is based on an Nd:YAG laser. The beam is focused on the test sample by using an optical scanner to create the required lateral heat flow. The time resolved temperature distribution is recorded with an infrared camera (InSb FPA, 3 to 5 μm) providing a frame rate of up to 500 Hz. In addition we report on numerical simulation to investigate the concept of local heat excitation for a quantitative estimation of crack parameters. The modeling also includes the influence of surface to surface radiation inside the crack. We obtained a good consistency between experimental and theoretical data.

  11. Enhanced Strength via crack friction and Pressure

    Science.gov (United States)

    Wiegand, Donald; Ellis, Kevin; Leppard, Claire

    2011-03-01

    The effect of pressure on the mechanical response of particulate polymer composites is being studied. Between about 0.1 and 7 MPa for one composite the results indicate that slow crack growth is the dominant failure mode. With continuously creasing strain at low pressures the stress initially increases to a maximum, the compressive strength, then decreases indicating work softening and them becomes approximately constant at a plateau value. Both the compressive strength and the plateau stress increases linearly with pressure but the plateau stress increases with a steeper slope such that at higher pressures work softening is not observed. The results are analyzed in terms of shear cracks with friction between the crack surfaces. The model predicts a threshold stress for crack growth which increases linearly with pressure and further predicts that the compressive strength increases linearly with pressure as observed and with the same slope as the threshold stress. These results clearly indicate that the pressure dependence of the compressive strength is due to the pressure dependence of the threshold stress for crack growth. The changes in the plateau region can also be attributed to frictional effects. Supported by AWE Aldermaston.

  12. Shaft Crack Identification Based on Vibration and AE Signals

    Directory of Open Access Journals (Sweden)

    Wenxiu Lu

    2011-01-01

    Full Text Available The shaft crack is one of the main serious malfunctions that often occur in rotating machinery. However, it is difficult to locate the crack and determine the depth of the crack. In this paper, the acoustic emission (AE signal and vibration response are used to diagnose the crack. The wavelet transform is applied to AE signal to decompose into a series of time-domain signals, each of which covers a specific octave frequency band. Then an improved union method based on threshold and cross-correlation method is applied to detect the location of the shaft crack. The finite element method is used to build the model of the cracked rotor, and the crack depth is identified by comparing the vibration response of experiment and simulation. The experimental results show that the AE signal is effective and convenient to locate the shaft crack, and the vibration signal is feasible to determine the depth of shaft crack.

  13. Study of the effect of ionizing radiation for utilization of spent cracking catalysts

    International Nuclear Information System (INIS)

    Catalyst is a substance that changes the rate of a reaction. In the petroleum industry the commonly catalysts are used for Fluid Catalytic Cracking (FCC) and Hydrocatalytic Cracking (HCC), which one applied in a specific stage. These catalysts are used to facilitate the molecular chains cracking which will generate a mixture of hydrocarbons. However, the catalyst gradually loses its activity, either by changing its original molecular structure or by its contamination from other petroleum molecules. The application of ionizing radiation (electron beam and gamma rays) over these spent catalysts was studied to contribute with the extraction of metals or rare-earths of high added-value. Tests carried out with FCC catalysts were used the techniques of 60Co irradiation and electron beam (EB) and had as a subject the extraction of lanthanum (La2O3), regeneration and utilization of these catalysts. However, the use of ionizing radiation has not contributed in these processes. Meanwhile with HCC catalysts the irradiation used was electron beam and had as a subject the extraction of molybdenum (MoO3). In temperature around 750°C, these irradiated catalysts of the lower region have an extraction yield twice higher compared to non-irradiated ones, in other words 57.65% and 26.24% respectively. (author)

  14. Propagation of stress corrosion cracks in alpha-brasses

    Energy Technology Data Exchange (ETDEWEB)

    Beggs, Dennis Vinton

    1981-01-01

    Transgranular and intergranular stress corrosion cracks were investigated in alpha-brasses in a tarnishing ammoniacal solution. Surface observation indicated that the transgranular cracks propagated discontinuously by the sudden appearance of a fine crack extending several microns ahead of the previous crack tip, often associated with the detection of a discrete acoustic emission (AE). By periodically increasing the deflection, crack front markings were produced on the resulting fracture surfaces, showing that the discontinuous propagation of the crack trace was representative of the subsurface cracking. The intergranular crack trace appeared to propagate continuously at a relatively blunt crack tip and was not associated with discrete AE. Under load pulsing tests with a time between pulses, ..delta..t greater than or equal to 3 s, the transgranular fracture surfaces always exhibited crack front markings which corresponded with the applied pulses. The spacing between crack front markings, ..delta..x, decreased linearly with ..delta..t. With ..delta..t less than or equal to 1.5 s, the crack front markings were in a one-to-one correspondence with applied pulses only at relatively long crack lengths. In this case, ..delta..x = ..delta..x* which approached a limiting value of 1 ..mu..m. No crack front markings were observed on intergranular fracture surfaces produced during these tests. It is concluded that transgranular cracking occurs by discontinuous mechanical fracture of an embrittled region around the crack tip, while intergranular cracking results from a different mechanism with cracking occurring via the film-rupture mechanism.

  15. Sizing stress corrosion cracks using laser ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Hamood; McNealy, Rick; Fingerhut, Martin [Applus-RTD. Houston, TX (United States); Klein, Marvin; Ansari, Homayoon [Intelligent Optical Systems, Inc. Los Angeles, CA (United States); Kania Richard [TransCanada. Calgary, AB (Canada); Rapp, Steve [Spectra Energy, Houston, TX (United States)

    2010-07-01

    Despite various efforts, no reliable tools and techniques are available to enable an operator to quantify the impact of an SCC (Stress Corrosion Cracking) colony on the safety and integrity of a pipeline. Reliable non-destructive detection and measurement tools are not available either. There is therefore a large gap between current technology and the needs of the pipeline industry. Recent developments promise that with a concentrated effort, a comprehensive solution can be devised. This paper describes technical work performed to develop and validate both the inspection tool and the time of flight diffraction (TOFD) technique for sizing the depth of SCC. It also presents preliminary results of work on a closely related project that provides, on the basis of this technology, an integrated approach and tool for mapping, sizing, and evaluating SCC, through which significant cracks are filtered from more benign cracks within an SCC colony.

  16. Inverse Crack Problems in Piezoelectric Solids

    Science.gov (United States)

    Sladek, Jan; Sladek, Vladimir; Zhang, Chuanzeng

    2010-05-01

    In the present paper, the meshless local Petrov-Galerkin (MLPG) method is applied to cracked piezoelectric solids under a stationary or transient dynamic load and unspecified electrical conditions on the crack surfaces. On the outer surface of the cracked solid the electrical boundary conditions are over-specified. The coupled governing partial differential equations are satisfied in a weak-form on small fictitious sub-domains. Nodal points are introduced and spread on the analyzed domain and each node is surrounded by a small circle for simplicity, but without loss of generality. The spatial variations of the displacements and the electric potential are approximated by the Moving Least-Squares (MLS) scheme. After performing the spatial integrations, a system of linear algebraic equations for unknown nodal values is obtained. Singular value decomposition (SVD) is applied to solve the ill-conditioned linear system of algebraic equations obtained from the local integral equations (LIEs) after the MLS approximation.

  17. Environmentally assisted cracking in LWR materials

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K.; Chung, H.M.; Kassner, T.F.; Park, J.H.; Shack, W.J. [Argonne National Lab., IL (United States); Zhang, J.; Brust, F.W.; Dong, P. [Battelle Columbus Labs., Columbus, OH (United States)

    1998-03-01

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2--0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  18. In situ fatigue-crack-propagation experiment

    International Nuclear Information System (INIS)

    An in-reactor fatigue experiment was conducted in the Oak Ridge Research Reactor to determine the effects of dynamic irradiation on fatigue crack propagation. Eight 20% cold-worked 316 stainless steel specimens were precracked to various initial crack lengths, linked together to form a chain, and inserted into a specially designed in-reactor fatigue machine. Test conditions included a maximum temperature of 4600C, an environment of sodium, a frequency of 1 cycle/min, and a stress ratio of 0.10. Results indicated that (1) no effects of dynamic irradiation were observed for a fluence of 1.5 x 1021 n/cm2 (E > 0.1 MeV); and (2) crack growth rates in elevated temperature sodium were a factor of 3 to 4 lower than in room temperature air

  19. Crack velocity jumps engendered by a transformational process zone

    Science.gov (United States)

    Boulbitch, A.; Korzhenevskii, A. L.

    2016-06-01

    We study a concerted propagation of a fast crack with the process zone where a rearrangement of the solid structure takes place. The latter is treated as a second-order local phase transformation. We demonstrate that the propagation of such a zone gives rise to a nonlinear frictionlike force exerted on the crack tip, resisting its propagation. Depending on the temperature, it produces three regimes of crack motion, which differ in the behavior of the crack tip process zone: (i) always existing, (ii) only emerging at a high crack speed, and (iii) flickering. We show that the latter regime exhibits crack velocity jumps.

  20. Velocity-Dependent Fatigue Crack Paths in Nanograined Pt Films

    Science.gov (United States)

    Meirom, R. A.; Clark, T.; Polcawich, R.; Pulskamp, J.; Dubey, M.; Muhlstein, C. L.

    2008-08-01

    Studies of crack growth in nanograined films assert that mechanical damage accumulates at grain boundaries irrespective of the crack velocity and loading conditions. This work shows that crack advance in nanograined Pt films involves a dislocation-slip mechanism that is a function of the crack growth rate and mode of loading. Crack paths in Pt were initially intergranular, but transitioned to a transgranular mode that persisted until catastrophic failure. This research demonstrates that crack growth mechanisms modeled for nanograined Ni cannot be generalized to other pure, metallic systems.

  1. A Pipeline Fracture Model of Hydrogen-induced Cracking

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The relationship between hydrogen concentration and crack tip stress, strain field, hydrogen diffusion and internal pressure respectively in the crack tip process zone was investigated, and the length of the crack tip process zone of hydrogen-induced cracking (HIC) was determined. Based on the mechanism of fracture of micro-crack nucleation, a dislocation model was presented for the fracture criteria of HIC. The influence factors of pipeline tube fracture ductile KISCC in the presence of hydrogen was analyzed, and the critical pressure bearing capability of a pipeline with hydrogen-induced cracking and the critical J-integrity (JISCC) were calculated, which is very important for pipeline safety.

  2. LOSA-1型增产丙烯助剂在呼和浩特石化公司催化裂化装置上的试用总结%Trial Conclusions on Using LOSA-1 Catalyst-aided in Catalytic Cracking Unit

    Institute of Scientific and Technical Information of China (English)

    关丰忠; 王勇; 乌日达

    2005-01-01

    本文主要论述了LOSA-1型增产丙烯助剂在呼石化公司催化裂化装置上的应用情况.分析说明了LOSA-1型增产丙烯助剂在增加催化裂化装置高附加值产品丙稀的能力以及改善催化裂化装置的产品分布等方面发挥的作用.

  3. Realistic and efficient 2D crack simulation

    Science.gov (United States)

    Yadegar, Jacob; Liu, Xiaoqing; Singh, Abhishek

    2010-04-01

    Although numerical algorithms for 2D crack simulation have been studied in Modeling and Simulation (M&S) and computer graphics for decades, realism and computational efficiency are still major challenges. In this paper, we introduce a high-fidelity, scalable, adaptive and efficient/runtime 2D crack/fracture simulation system by applying the mathematically elegant Peano-Cesaro triangular meshing/remeshing technique to model the generation of shards/fragments. The recursive fractal sweep associated with the Peano-Cesaro triangulation provides efficient local multi-resolution refinement to any level-of-detail. The generated binary decomposition tree also provides efficient neighbor retrieval mechanism used for mesh element splitting and merging with minimal memory requirements essential for realistic 2D fragment formation. Upon load impact/contact/penetration, a number of factors including impact angle, impact energy, and material properties are all taken into account to produce the criteria of crack initialization, propagation, and termination leading to realistic fractal-like rubble/fragments formation. The aforementioned parameters are used as variables of probabilistic models of cracks/shards formation, making the proposed solution highly adaptive by allowing machine learning mechanisms learn the optimal values for the variables/parameters based on prior benchmark data generated by off-line physics based simulation solutions that produce accurate fractures/shards though at highly non-real time paste. Crack/fracture simulation has been conducted on various load impacts with different initial locations at various impulse scales. The simulation results demonstrate that the proposed system has the capability to realistically and efficiently simulate 2D crack phenomena (such as window shattering and shards generation) with diverse potentials in military and civil M&S applications such as training and mission planning.

  4. Role of plasticity-induced crack closure in fatigue crack growth

    Directory of Open Access Journals (Sweden)

    Jesús Toribio

    2013-07-01

    Full Text Available The premature contact of crack surfaces attributable to the near-tip plastic deformations under cyclic loading, which is commonly referred to as plasticity induced crack closure (PICC, has long been focused as supposedly controlling factor of fatigue crack growth (FCG. Nevertheless, when the plane-strain near-tip constraint is approached, PICC lacks of straightforward evidence, so that its significance in FCG, and even the very existence, remain debatable. To add insights into this matter, large-deformation elastoplastic simulations of plane-strain crack under constant amplitude load cycling at different load ranges and ratios, as well as with an overload, have been performed. Modeling visualizes the Laird-Smith conceptual mechanism of FCG by plastic blunting and re-sharpening. Simulation reproduces the experimental trends of FCG concerning the roles of stress intensity factor range and overload, but PICC has never been detected. Near-tip deformation patterns discard the filling-in a crack with material stretched out of the crack plane in the wake behind the tip as supposed PICC origin. Despite the absence of closure, load-deformation curves appear bent, which raises doubts about the trustworthiness of closure assessment from the compliance variation. This demonstrates ambiguities of PICC as a supposedly intrinsic factor of FCG and, by implication, favors the stresses and strains in front of the crack tip as genuine fatigue drivers.

  5. Evolution of residual stresses with fatigue crack growth in integral structures with crack retarders

    International Nuclear Information System (INIS)

    Bonded straps are investigated for their ability to retard a growing fatigue crack in metallic structures. The evolution of the residual stresses in the vicinity of the strap with fatigue crack growth has been studied. Cracks were grown in single edge-notched tension (SEN(T)) specimens reinforced with either a titanium or a carbon fibre reinforced plastics (CFRP) strap. The residual stress evolution has been measured in situ during crack growth using neutron diffraction, and modelled with a finite element approach. The peak residual stresses induced by the mismatch of the coefficient of thermal expansion between the strap and plate materials were seen to be fairly constant with crack growth. Good correlation between the experimental and the modelling results was found, except at very long crack lengths for a specimen that exhibited considerable fracture surface roughness at long crack lengths. The difference was attributed to wedging of the fracture surface changing the expected stress state, rather than any effect of the strap.

  6. Fatigue crack initiation life prediction of railroad

    International Nuclear Information System (INIS)

    Study of multiaxial high-cycle fatigue initiation life prediction for railroad is done in this paper. Using ANSYS 11.0 software three dimensional elasto-plastic finite element model of rail/wheel contact is constructed and fine mesh technique in contact region is used to achieve both computational efficiency and accuracy. Stress analysis is performed and fatigue damage in railroad is evaluated numerically using multiaxial fatigue crack initiation model. Using the stress history during one loading cycle and fatigue damage model, the effects of vertical loading, material hardness material fatigue properties and wheel/rail contact situation on fatigue crack initiation life are investigated.

  7. Multiple Gastrointestinal Complications of Crack Cocaine Abuse

    Directory of Open Access Journals (Sweden)

    Neal Carlin

    2014-01-01

    Full Text Available Cocaine and its alkaloid free base “crack-cocaine” have long since been substances of abuse. Drug abuse of cocaine via oral, inhalation, intravenous, and intranasal intake has famously been associated with a number of medical complications. Intestinal ischemia and perforation remain the most common manifestations of cocaine associated gastrointestinal disease and have historically been associated with oral intake of cocaine. Here we find a rare case of two relatively uncommon gastrointestinal complications of hemorrhage and pancreatitis presenting within a single admission in a chronic crack cocaine abuser.

  8. LABORATORY STUDY ON CRACKS IN SATURATED SANDS

    Institute of Scientific and Technical Information of China (English)

    Peng Fujiao; Tan Qingming; Che-Min Cheng

    2000-01-01

    It has been reported[1]that when a loosely packed column of saturated sand in a vertical cylindrical container is shock loaded axially by dropping to the floor,large horizontal cracks initiate,grow and eventually fade away in the sand as it settles under gravity.This paper shows that a similar phenomenon can also be observed when shock loading is replaced by forcing water to percolate upward through the sand column.It is believed that our result sheds further light on the physics of formation of these cracks.

  9. Detection of wear cracks by photothermal radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, J.L. (Groupe de Recherche Surfaces et Materiaux, Lab. d' Energetique et d' Optique, Faculte des Sciences, 51 - Reims (France)); Menu, C. (Groupe de Recherche Surfaces et Materiaux, Lab. d' Energetique et d' Optique, Faculte des Sciences, 51 - Reims (France)); Egee, M. (Groupe de Recherche Surfaces et Materiaux, Lab. d' Energetique et d' Optique, Faculte des Sciences, 51 - Reims (France)); Pigeon, P. (Commissariat a l' Energie Atomique, Centre d' Etudes et de Recherche sur les Materiaux, Centre d' Etudes Nucleaires Saclay, 91 - Gif-sur-Yvette (France)); Blanc, A. le (Commissariat a l' Energie Atomique, Centre d' Etudes et de Recherche sur les Materiaux, Centre d' Etudes Nucleaires Saclay, 91 - Gif-sur-Yvette (France))

    1993-04-13

    Among the non-destructive techniques, testing methods using thermal waves are starting to be developed in industry. Photothermal radiometry under cw excitation, which is one of these methods, has been used in this work for the detection of wear cracks, either emerging on the surface of the sample or covered with a thin layer. Before conducting the experimental study, we have developed a three-dimensional mathematical model. It is shown that the influence of the flaw on the photothermal signal is indeed the result of two phenomena: a thermal barrier effect and an optical effect owing to the higher emissivity of the crack when it is emerging. (orig.)

  10. Wuergassen to be decommissioned. Cracks in the core shroud did not create a hazard

    International Nuclear Information System (INIS)

    Cracks in the core shroud have been detected in several boiling water reactor plants in the United States of America, Japan, Taiwan, Switzerland and Sweden. To this date, findings of this type have been made in a total of 23 plants. Also visual inspection of the core shroud of the Wuergassen Nuclear Power Station revealed cracks during the 1994 revision. The cause was found to be intergranular stress corrosion cracking (SCC) in 1.4550 type austenitic material sensitized by heat treatment. Safety assessment indicated no impairment of functional reliability either during normal operation or under accident conditions. Economic and licensing constraints prevented repair of the core shroud, although this has been achieved successfully in the United States and in Japan. Consequently, replacement of the core shroud was prepared in the planning stage, and the feasibility of this step was demonstrated. However, the fundamental modernization of the entire plant, which would have been necessary in case of replacement of the core shroud, caused PreussenElektra to decide on decommissioning the Wuergassen plant on economic grounds. This is the first decommissioning decision about a commercial nuclear power plant in the old German federal states. Inspections of the other German boiling water reactor plants did not result in any indications of cracks in the core shroud area. (orig./GL)

  11. Particle Discrete Method Based on Manifold Cover for Crack Propagation of Jointed Rock Mass

    Directory of Open Access Journals (Sweden)

    Yang Ping

    2014-01-01

    Full Text Available The rock mass can be assumed to be homogeneous material from a macroscopic view; however, it is the heterogeneous material in mesoscopic scale and its physicomechanical properties are discontinuous in space. The failure of jointed rock mass was usually caused by the initiation, propagation, and coalescence of new wing cracks derived from primary joint. In order to further study the rock fracture instability, we need to study the expansion of rock cracks under external loads from the macro-meso perspective. This paper, based on the manifold cover concept, proposes a new discrete element numerical method, manifold particle discrete (MPD, combined with the particle contact model and the introduced concept of stress boundary. The proposed method can easily simulate the crack generation, propagation, and coalescence of jointed rock mass from the macro-meso perspective. The whole process of rock fragmentation is thereafter reproduced. By analyzing the manifold cover and sphere particle model, this paper constitutes the sphere unit cover function of three-dimensional manifold cover, establishes tetrahedron units, and obtains the equilibrium equation and compatible equation of the MPD model. For rock-like brittle material, crack propagation process can be simulated, and it also verifies the accuracy of the proposed numerical method.

  12. CRACK2. Modelling calcium carbonate deposition from bicarbonate solutions in cracks in concrete

    DEFF Research Database (Denmark)

    Brodersen, Knud Erik

    2003-01-01

    by diffusion in pore systems in columns of cementitious materials. The hydroxyl is precipitating calcite from a flow of bicarbonate solution in a crack connecting the ends of a row of such columns. Thecementitious material is simulated as calcium hydroxide mixed with inert material but with sodium hydroxide...... and on the composition of the outflowing solution, which can be compared directly with experimental results.Leaching behavior of sodium can be used to tune the model to experimental observations. The calcite is mostly precipitated on top of the original crack surface and may under certain circumstances fill the crack...

  13. Experimental study of heat dissipation at the crack tip during fatigue crack propagation

    Directory of Open Access Journals (Sweden)

    A. Vshivkov

    2016-01-01

    Full Text Available This work is devoted to the development of an experimental method for studying the energy balance during cyclic deformation and fracture. The studies were conducted on 304 stainless steel AISE and titanium alloy OT4-0 samples. The investigation of the fatigue crack propagation was carried out on flat samples with different geometries and types of stress concentrators. The heat flux sensor was developed based on the Seebeck effect. This sensor was used for measuring the heat dissipation power in the examined samples during the fatigue tests. The measurements showed that the rate of fatigue crack growth depends on the heat flux at the crack tip.

  14. Coke Formation During Hydrocarbons Pyrolysis. Part One: Steam Cracking Formation de coke pendant la pyrolise des hydrocarbures. Première partie : vapocraquage

    OpenAIRE

    Weill J.; Broutin P.; Billaud F.; Gueret C.

    2006-01-01

    Thermal cracking is always accompanied by coke formation, which becomes deposited on the wall and limits heat transfers in the reactor while increasing pressure drops and possibly even plugging up the reactor. This review article covers undesirable coking operations in steam craking reactors. These coking reactions may take place in the gas phase and/or on the surface of the reactor, with coke being produced during pyrolysis by a complex mechanism that breaks down into a catalytic sequence an...

  15. An evaluation on fatigue crack growth in a fine-grained isotropic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hongtao; Sun Libin [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Li Chenfeng [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Shi Li [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Wang Haitao, E-mail: wanght@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2012-09-15

    main cause of the fatigue fracture is the shear stress. There are also a large amount of secondary cracks inside unit cells and on cell walls, which indicates the fracture mechanism of the IG-11 graphite is mainly cleavage fracture.

  16. Combined catalytic converter and afterburner

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-30

    This patent describes the combined use of a catalytic converter and afterburner. An afterburner chamber and a catalyst matrix are disposed in series within a casing. A combustible premixed charge is ignited in the afterburner chamber before it enters the catalyst matrix. This invention overcomes the problem encountered in previous designs of some of the premixed charge passing unreacted through the device unless a very long afterburner chamber is used. (UK)

  17. Thermodynamics of catalytic nanoparticle morphology

    Science.gov (United States)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  18. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  19. [Current research situation of H2S selective catalytic oxidation technologies and catalysts].

    Science.gov (United States)

    Hao, Zheng-ping; Dou, Guang-yu; Zhang, Xin; Qu, Si-qiu

    2012-08-01

    This review summarizes and discusses different selective catalytic oxidation technologies and various catalysts for removing H2S, the undesirable byproduct of the fluid catalytic cracking (FCC) processing. Currently the selective oxidation technologies used include Superclaus, Euroclaus, Clinsulf-Do, BSR/Hi-Activity, Selectox and Modop techniques, which have various characteristics and application areas. Catalysts for H2S selective oxidation mainly contain the following systems: carbon, supported SiC, zeolite, oxide, and pillared clay. Former studies focused on carbon and oxide systems. The research interest on zeolite system decreased in recent years, while SiC is regarded as a typical support with great potential for this reaction and continues to be attractive. Pillared clay system is at the preliminary research stage, and is still far from practical application.

  20. Effects of plastic anisotropy on crack-tip behaviour

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Tvergaard, Viggo; Kuroda, Mitsutoshi

    2002-01-01

    For a crack in a homogeneous material the effect of plastic anisotropy on crack-tip blunting and on the near-tip stress and strain fields is analyzed numerically. The full finite strain analyses are carried out for plane strain under small scale yielding conditions, with purely symmetric mode I...... loading remote from the crack-tip. In cases where the principal axes of the anisotropy are inclined to the plane of the crack it is found that the plastic zones as well as the stress and strain fields just around the blunted tip of the crack become non-symmetric. In these cases the peak strain...... on the blunted tip occurs off the center line of the crack, thus indicating that the crack may want to grow in a different direction. When the anisotropic axes are parallel to the crack symmetry is retained, but the plastic zones and the near-tip fields still differ from those predicted by standard isotropic...

  1. Crack Growth along Interfaces in Porous Ceramic Layers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Horsewell, Andy

    2001-01-01

    Crack growth along porous ceramic layers was studied experimentally. Double cantilever beam sandwich specimens were loaded with pure bending moments to obtain stable crack growth. The experiments were conducted in an environmental scanning electron microscope enabling in situ observations of...

  2. Chloride Ingress in Concrete Cracks under Cyclic Loading

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Olesen, John Forbes;

    2005-01-01

    Traditional approaches towards service life design and redesign of reinforced concrete are based on the assumption of a homogenous uncracked concrete. This assumption is questionable, as concrete always contains cracks and cracks affect the ingress rate of aggressive substances. Thus...

  3. A MOVING CRACK IN A NONHOMOGENEOUS MATERIAL STRIP

    Institute of Scientific and Technical Information of China (English)

    Wang Baolin; Han Jiecai

    2006-01-01

    This paper considers an anti-plane moving crack in a nonhomogencous material strip of finite thickness. The shear modulus and the mass density of the strip are considered for a class of functional forms for which the equilibrium equation has analytical solutions. The problem is solved by means of the singular integral equation technique. The stress field near the crack tip is obtained. The results are plotted to show the effect of the material non-homogeneity and crack moving velocity on the crack tip field. Crack bifurcation behaviour is also discussed. The paper points out that use of an appropriate fracture criterion is essential for studying the stability of a moving crack in nonhomogeneous materials. The prediction whether the unstable crack growth will be enhanced or retarded is strongly dependent on the type of the fracture criterion used. is a suitable failure criterion for moving cracks in nonhomogeneous materials.

  4. Acoustic emission assessment of interface cracking in thermal barrier coatings

    Science.gov (United States)

    Yang, Li; Zhong, Zhi-Chun; Zhou, Yi-Chun; Zhu, Wang; Zhang, Zhi-Biao; Cai, Can-Ying; Lu, Chun-Sheng

    2016-04-01

    In this paper, acoustic emission (AE) and digital image correlation methods were applied to monitor interface cracking in thermal barrier coatings under compression. The interface failure process can be identified via its AE features, including buckling, delamination incubation and spallation. According to the Fourier transformation of AE signals, there are four different failure modes: surface vertical cracks, opening and sliding interface cracks, and substrate deformation. The characteristic frequency of AE signals from surface vertical cracks is 0.21 MHz, whilst that of the two types of interface cracks are 0.43 and 0.29 MHz, respectively. The energy released of the two types of interface cracks are 0.43 and 0.29 MHz, respectively. Based on the energy released from cracking and the AE signals, a relationship is established between the interface crack length and AE parameters, which is in good agreement with experimental results.

  5. Vibration Pattern Related to Transverse Cracks in Rotors

    OpenAIRE

    Nicolò Bachschmid; Ezio Tanzi

    2002-01-01

    A method for calculating the breathing behavior of transverse cracks of different types in rotating shafts is described. Thermal effects are included. Some results in terms of vibration excitation related to different shapes of cracks are presented.

  6. Partial discharge-induced crack growth in dielectric materials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Partial discharge(PD) of an air-filled semi-permeable crack in a dielectric material is studied based on the streamer-type discharge mechanism to explore the effects of applied mechanical-electric fields on crack growth.Within the frame of two-dimensional deformation,the electric field inside the crack is first derived by taking the crack deformation into account.Then,the effects of electric field before PD are discussed through considering the contribution of the induced electric field inside the deformed crack space to the total energy release rate.Finally,PD and its effects on crack growth are investigated.It is found that:(1) before PD,the applied electric field always retards crack growth;(2) during PD,the applied electric field can induce crack growth in dielectric materials.

  7. Fatigue crack shape prediction based on vertex singularity

    Directory of Open Access Journals (Sweden)

    Hutař P.

    2008-11-01

    Full Text Available Due to the existence of vertex singularity at the point where the crack intersects the free surface, stress distribution around the crack tip and the type of the singularity is changed. In the interior of the specimen the classical singular behaviour of the crack is dominant and can be described using analytic equations. Contrary to this, at the free surface or in the boundary layer close to free surface the vertex singularity is significant. The influence of vertex singularity on crack behaviour and a crack shape for a three-dimensional structure is described in this paper. The results presented make it possible to estimate fatigue crack growth rate and crack shape using the concept of the generalized stress intensity factor. The estimated fatigue crack shape can help to provide a more reliable estimation of the fatigue life of the structures considered.

  8. Environmentally assisted cracking in light water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K.; Chung, H.M.; Gruber, E.E. [and others

    1996-07-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from April 1995 to December 1995. Topics that have been investigated include fatigue of carbon and low-alloy steel used in reactor piping and pressure vessels, EAC of Alloy 600 and 690, and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests were conducted on ferritic steels in water that contained various concentrations of dissolved oxygen (DO) to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack-growth-rate tests were conducted on compact-tension specimens from several heats of Alloys 600 and 690 in simulated LWR environments. Effects of fluoride-ion contamination on susceptibility to intergranular cracking of high- and commercial- purity Type 304 SS specimens from control-tensile tests at 288 degrees Centigrade. Microchemical changes in the specimens were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials.

  9. Stress Corrosion Cracking of Pipeline Steels

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper provides a review of the differences between high pH and near-neutral pH stress corrosion cracking ofpipeline steels, influencing factors, and mechanisms. The characteristics and historical information on both forms ofSCC are discussed. The prospect for research in the future is also presented.

  10. Next Generation Steam Cracking Reactor Concept

    NARCIS (Netherlands)

    Van Goethem, M.W.M.

    2010-01-01

    The steam cracking process is an important asset in the hydrocarbon processing industry. The main products are lower olefins and hydrogen, with ethylene being the world's largest volume organic chemical at a worldwide capacity of ~ 120 million tonnes per year. Feed stocks are hydrocarbons such as: e

  11. Fatigue crack growth in Aluminium Alloys

    NARCIS (Netherlands)

    Van Kranenburg, C.

    2010-01-01

    Fatigue is a gradual process of local strength reduction. It is a phenomenon of damage accumulation at stress concentrations caused by fluctuating stresses and/or strains. In metals this results in microscopic cracks. These will start to grow under continued cyclic loading until final failure occurs

  12. Kinetic studies of stress-corrosion cracking

    Science.gov (United States)

    Noronha, P. J.

    1977-01-01

    Use of time-to-failure curves for stress-corrosion cracking processes may lead to incorrect estimates of structural life, if material is strongly dependent upon prestress levels. Technique characterizes kinetics of crackgrowth rates and intermediate arrest times by load-level changes.

  13. 3D characterisation of RCF crack networks

    Directory of Open Access Journals (Sweden)

    Ahlström Johan

    2014-06-01

    Full Text Available Rolling contact fatigue (RCF damage is becoming more frequent with increased traffic and loading conditions in the railway industry. Defects which are characterized by a two-lobe darkened surface and a V-shaped surface-breaking crack are often so-called squats. The origination and propagation of squats in railway rails is the topic of many recent studies; the associated crack networks develop with complicated geometry near the surface of rails that is difficult to characterise using most non-destructive methods. The cracks can be examined with repeated metallographic sectioning, but the process is time-consuming and destructive. In order to reduce time, as well as information and material loss, high-resolution and high-energy X-ray imaging of railway rails was done in the current study. Combining the exposures from a range of angles using image analysis, a 3D representation of the complex crack network is achieved. The latter was complemented with metallographic sectioning to determine the accuracy of prediction of the geometrical reconstruction.

  14. Effect of flow velocity on crack initiation

    International Nuclear Information System (INIS)

    Constant extension rate tensile (CERT) tests are traditionally used to understand the influence of material composition, heat treatment, temperature and environmental variables on stress corrosion crack (SCC) initiation. However, fluid flow rate has not been investigated as a parameter that could affect SCC initiation until recently. These studies have exhibited longer time to failure under high flow conditions indicating delayed crack initiation. Because these experiments have been performed in highly oxygenated water, no correlation has been established between the influence of flow velocity on the electrochemical corrosion potential (ECP) and the time to failure of tensile test specimens. The interrelationship between the fluid flow velocity, ECP and the time to failure is of great interest to the Boiling Water Reactor (BWR) applications primarily because of the previous observations that the ECP of Type 304 stainless steel increases with fluid flow velocity. This paper describes an attempt that has been made to understand the interrelationship between fluid flow velocity, ECP and the time for crack initiation in high temperature high purity water simulating both the BWR chemistry and the component flow velocity conditions. The range of flow velocities employed in the present study was 0.002 to 2 ft/s. The studies indicate that while high flow velocities can increase ECP there is a delayed effect on crack initiation

  15. Instantaneous crack detection using dual PZT transducers

    Science.gov (United States)

    Kim, Seung Bum; Sohn, Hoon

    2008-03-01

    A new guided wave based nondestructive testing (NDT) technique is developed to detect crack damage in metallic plates commonly used in aircraft without using prior baseline data or a predetermined decision boundary. In conventional guided wave based techniques, damage is often identified by comparing the "current" data obtained from a potentially damaged condition of a structure with the "past" baseline data collected at the pristine condition of the structure. However, it has been reported that this type of pattern comparison with the baseline data can lead to increased false alarms due to its susceptibility to varying operational and environmental conditions of the structure. In order to tackle this issue, a reference-free damage detection technique is previously developed using two pairs of collocated lead zirconate titanate transducers (PZTs) placed on both sides of a plate. In this study, this reference-free technique is further advanced so that the PZT transducers can be placed only on one side of the specimen. Crack formation creates Lamb wave mode conversion due to a sudden change in the thickness of the structure. Then, the proposed technique instantly detects the appearance of the crack by extracting this mode conversion from the measured Lamb waves. This study suggests a reference-free statistical approach that enables damage classification using only the current data set. Numerical and experimental results are presented to demonstrate the applicability of the proposed technique to instantaneous crack detection.

  16. SURFACING ELECTRODE WITH CRACKING RESISTANCE AND WEARABILITY

    Institute of Scientific and Technical Information of China (English)

    Yang Shanglei; Lu Xueqin; Lou Songnian; Zou Zengda

    2005-01-01

    A new surfacing electrode is developed with cracking resistance and wearability based on high microhardness of TiC and VC, carbides of Ti and V are formed in deposited metal by means of high temperature arc metallurgic reaction. The results show the hardness of surfacing metal increases with the increase of ferrotitanium (Fe-Ti), ferrovanadium (Fe-V) and graphite in the coat. However,when graphite reaches the volume fraction of 11%, the hardness reaches its peak value, and when beyond 11%, the hardness falls off. As Fe-Ti, Fe-V and graphite increase, the cracking resistance of deposited metal and usability of electrode declines. Carbides are dispersedly distributed in the matrix structure. The matrix microstructure of deposited metal is lath martensite. Carbides present irregular block. When using the researched surfacing electrode to continue weld with non-preheated, no seeable crack or only a few micro-cracks can be observed in the surface of deposited metal. The hardness is above 60 HRC. The wear resistance is better than that of EDZCr-C-15.

  17. Crack detection by mobile photothermal probe

    Energy Technology Data Exchange (ETDEWEB)

    Besnard, R.; Le Blanc, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Technologie des Materiaux; Bodnar, J.L.; Egee, M.; Menu, C. [Reims Univ., 51 (France); Sellier, J.Y. [Societe Intercontrole, 94 - Rungis (France)

    1993-12-31

    This paper deals with an industrial method for crack detection. The apparatus presented is based on a mobile photothermal probe. It can be used under different modes (sinusoidal, pulsed or scanned excitation). Moreover, the description of the device provided includes theoretical and experimental results. (TEC). 7 refs., 6 figs.

  18. 46 CFR 59.10-5 - Cracks.

    Science.gov (United States)

    2010-10-01

    ... does not exceed 12 inches in length and after completion the weld is stress-relieved. Cracks in... the root of the weld shall be chipped or ground out to insure a clean surface of the originally... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed....

  19. ANN modeling of industrial FCC unit%催化裂化装置的人工神经网络建模

    Institute of Scientific and Technical Information of China (English)

    邓毅; 江青茵; 曹志凯; 师佳; 周华

    2011-01-01

    This paper discussed the application problems of artificial neural network(ANN) modeling of industrial fluid catalytic cracking unit (FCCU). Two neural network, the Levenberg-Marquardt Back Propagation (LMBP) neural network and the Radial Basis Function (RBF) neural network using the partial least square (PLS) algorithm were adopted in this work. Use the data from an Industrial FCCU, the training rate and the generalization capability of these two neural network models were compared. Online least square correction(LSC) was lead in this study to test the online weight modification of the RBF neural network model. The results show that RBFPLS neural network has a better performance in generalization capability and other aspects such as the training time and parameters determination. Besides, when LSC was used, the results became more satisfied.%催化裂化装置(fluid catalytic cracking unit,FCCU)对炼油厂的经济效益至关重要,本文主要探讨了人工神经网络在催化裂化装置建模中的应用.利用实际的工业数据分别采用LMBP,RBF PLS神经网络对某工厂的催化裂化装置进行了建模试验.将它们的拟合与泛化结果、学习速度以及参数调整进行了比较,其结果显示RBF PLS神经网络在收敛速度以及预测性能等方面均优于LMBP神经网络.此外,本文在神经网络模型的基础上对其进行了最小二乘校正,得到了比较满意的结果.

  20. Analytical Crack Model for 2-D Reinforced Concrete Structures

    Institute of Scientific and Technical Information of China (English)

    车铁; 宋玉普

    2002-01-01

    A two-dimensional smeared crack model for reinforced concrete members is presented. Special emphasis is placedon the bond between concrete and reinforcement as the main factor influencing tension stiffening in cracked reinforcedconcrete. With the derived tangential stress-strain equations for concrete in the direction perpendicular to the cracks, theconstitutive relationship for cracked reinforced concrete is established. Experimental specimens have been analyzed withthe analytical model, and the analytical and experimental results are found to be in good agreement.