WorldWideScience

Sample records for catalytic cracking units

  1. Radioisotope applications on fluidized catalytic cracking units

    International Nuclear Information System (INIS)

    Radioisotopes are used to trace the flow of all the phases of Fluidized Catalytic Cracking process in oil refineries. The gaseous phases, steam, hydrocarbon vapour and air, are generally traced using a noble-gas isotope, 41Ar, 79Kr or 85Kr. An appropriate tracer for the catalyst is produced by irradiating a catalyst sample in a nuclear reactor. The activation products,140La and 24Na provide appropriate radioactive 'labels' for the catalyst, which is reinjected into the FCC. An advantage of this approach is that it facilitates the study of the behaviour of different particle size fractions. Radioisotopes as sealed sources of gamma radiation are used to measure catalyst density variations and density distributions in critical parts of the unit. An important trend in radioisotope applications is the increasing use of the information they produce as inputs to or as validation of, mathematical process models. In line with the increasing sophistication of the models, the technology is undergoing continuous refinement. Developments include the investigation of more efficient, more convenient tracers, the introduction of systems to facilitate more rapid and comprehensive data acquisition and software refinements for enhanced data analysis

  2. 40 CFR 63.1564 - What are my requirements for metal HAP emissions from catalytic cracking units?

    Science.gov (United States)

    2010-07-01

    ... emissions from catalytic cracking units? 63.1564 Section 63.1564 Protection of Environment ENVIRONMENTAL... Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Catalytic Cracking... requirements for metal HAP emissions from catalytic cracking units? (a) What emission limitations and...

  3. 40 CFR 63.1565 - What are my requirements for organic HAP emissions from catalytic cracking units?

    Science.gov (United States)

    2010-07-01

    ... HAP emissions from catalytic cracking units? 63.1565 Section 63.1565 Protection of Environment... Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Catalytic Cracking Units, Catalytic Reforming Units, Sulfur Recovery Units, and Bypass Lines § 63.1565...

  4. 40 CFR Table 5 to Subpart Uuu of... - Initial Compliance With Metal HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    .... Subject to the NSPS for PM in 40 CFR 60.102 PM emissions must not exceed 1.0 kg/1,000 kg (1.0 lb/1,000 lb... Emission Limits for Catalytic Cracking Units 5 Table 5 to Subpart UUU of Part 63 Protection of Environment... Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery Units Pt....

  5. 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.

  6. 40 CFR Table 8 to Subpart Uuu of... - Organic HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... limit for each catalyst regenerator vent . . . 1. Subject to the NSPS for carbon monoxide (CO) in 40 CFR... in 40 CFR 60.103 a. CO emissions from the catalyst regenerator vent or CO boiler serving the... Catalytic Cracking Units 8 Table 8 to Subpart UUU of Part 63 Protection of Environment...

  7. Catalytic cracking process

    Science.gov (United States)

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  8. Economics for iso-olefin production using the fluid catalytic cracking unit

    Energy Technology Data Exchange (ETDEWEB)

    McClung, R.G.; Witoshkin, A.; Bogert, D.C.; Winkler, W.S. [Englehard Corp., Iselin, NJ (United States)

    1993-12-31

    The Clean Air Act of 1990 requires use of oxygenates in some gasolines to improve both CO and hydrocarbon auto tailpipe emissions. Various oxygenates are currently being used by the refining industry. For the fully integrated refinery having a fluid catalytic cracking unit, the most commonly used oxygenates are methyl tertiary butyl ether (MTBE) and tertiary amyl ether (TAME). The FCC unit produces the isobutylene and iso-amylases need for manufacture of both MTBE and TAME. The economics for an assumed refinery processing scheme for several FCC cases are examined giving estimates of income and investments for each case. Up to one-third of the total gasoline pool can be made in reformulated gasoline using TAME and MTBE with the FCC unit as the sole source of feedstock. This processing route is much more economical than the alternative scheme using butane isomerization/iosbutane dehydrogenation.

  9. Modeling of an Industrial Riser in the Fluid Catalytic Cracking Unit

    Directory of Open Access Journals (Sweden)

    Mehran Heydari

    2010-01-01

    Full Text Available Problem statement: The aim of this study is to obtain a model that can simulate the performance of an industrial fluid catalytic cracking unit in steady state. Approach: The reactions in the riser occur in a transported bed with the fluid and the solids in ideal plug flow. One of the main advantages of the model is that it does not include any partial differential equations. This facilitates the solution of the equations and makes the model particularly suitable for control studies. Results: To simulate the FCC riser, the four-lump model involved gas oil, gasoline, light gas and coke (to predict the Gas oil conversion and the product distribution has been developed. Conclusion: Simulation studies are performed to investigate the effect of changing various process variables, such as temperature, catalyst circulation rate and gasoil feed rate. The calculated data of the product distribution were agreed well with the experimental results.

  10. 40 CFR Table 9 to Subpart Uuu of... - Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... . . . 1. Subject to the NSPS for carbon monoxide (CO) in 40 CFR 60.103 Continuous emission monitoring system. Not applicable Not applicable. 2. Not subject to the NSPS for CO in 40 CFR 60.103 a. Continuous... Emissions From Catalytic Cracking Units 9 Table 9 to Subpart UUU of Part 63 Protection of...

  11. 40 CFR Table 13 to Subpart Uuu of... - Continuous Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... demonstrate continuous compliance by . . . 1. Subject to the NSPS for carbon monoxide (CO) in 40 CFR 60.103 CO... ppmv (dry basis). 2. Not subject to the NSPS for CO in 40 CFR 60.103 i. CO emissions from your catalyst... Emission Limits for Catalytic Cracking Units 13 Table 13 to Subpart UUU of Part 63 Protection...

  12. 40 CFR Table 10 to Subpart Uuu of... - Continuous Monitoring Systems for Organic HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... CFR 60.103. Not applicable Continuous emission monitoring system to measure and record the... NSPS for CO in 40 CFR 60.103 a. Thermal incinerator Continuous emission monitoring system to measure... Organic HAP Emissions From Catalytic Cracking Units 10 Table 10 to Subpart UUU of Part 63 Protection...

  13. 40 CFR Table 12 to Subpart Uuu of... - Initial Compliance With Organic HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... the NSPS for carbon monoxide (CO) in 40 CFR 60.103 CO emissions from your catalyst regenerator vent or... initial compliance. 2. Not subject to the NSPS for CO in 40 CFR 60.103 a. CO emissions from your catalyst... Emission Limits for Catalytic Cracking Units 12 Table 12 to Subpart UUU of Part 63 Protection...

  14. 40 CFR Table 6 to Subpart Uuu of... - Continuous Compliance With Metal HAP Emission Limits for Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... . . . 1. Subject to the NSPS for PM in 40 CFR 60.102 a. PM emissions must not exceed 1.0 kg/1,000 kg (1.0... subject to the NSPS for PM in 40 CFR 60.102 See item 1.a. of this table See item 1.a.i. of this table. 3... Emission Limits for Catalytic Cracking Units 6 Table 6 to Subpart UUU of Part 63 Protection of...

  15. Study of Seven-Lump Kinetic Model in the Fluid Catalytic Cracking Unit

    Directory of Open Access Journals (Sweden)

    Mehran Heydari

    2010-01-01

    Full Text Available Problem statement: The effective simulation of the Fluid Catalytic Cracking (FCC operation requires a good understanding of many factors such as, reaction kinetic, fluid dynamics and feed and catalyst effects. Approach: In this model the reactor has been considered as an isothermal riser. The reactions in the riser occur with the fluid and the solids in ideal plug flow. Because of complication of the catalytic cracking mechanism and existence of multi-components in the feed, to decrease the calculation content in the kinetic models, the reactants and products have been considered as a set of hydrocarbons, so these models are called Lumped Models. Results: To simulate the FCC riser, the seven-lump model involved residual oil, heavy lump, light lump, liquefied petroleum gas, gasoline, dry gas and coke (to predict the feed conversion and the product distribution has been developed. Conclusion: Simulation studies are performed to investigate the effect of changing various process variables, such as temperature and residence time. Comparison of simulation results with industrial ones shows that the simulation has been achieved accurately.

  16. 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.

  17. 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)

  18. 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)

  19. 40 CFR Table 14 to Subpart Uuu of... - Continuous Compliance With Operating Limits for Organic HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... demonstrate continuous compliance by . . . 1. Subject to NSPS for carbon monoxide (CO) in 40 CFR 60.103... to the NSPS for CO in 40 CFR 60.103 a. Continuous emission monitoring system Not applicable Complying... Limits for Organic HAP Emissions From Catalytic Cracking Units 14 Table 14 to Subpart UUU of Part...

  20. Refinery Nonconventional Feedstocks: Influence of the Coprocessing of Vacuum Gas Oil and Low Density Polyethylene in Fluid Catalytic Cracking Unit on Full Range Gasoline Composition

    OpenAIRE

    Odjo, Andrew O.; García Cortés, Ángela Nuria; Marcilla Gomis, Antonio

    2014-01-01

    Gasoline coming from refinery fluid catalytic cracking (FCC) unit is a major contributor to the total commercial grade gasoline pool. The contents of the FCC gasoline are primarily paraffins, naphthenes, olefins, aromatics, and undesirables such as sulfur and sulfur containing compounds in low quantities. The proportions of these components in the FCC gasoline invariable determine its quality as well as the performance of the associated downstream units. The increasing demand for cleaner and ...

  1. 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.

  2. Principal component analysis in an experimental cold flow model of a fluid catalytic cracking unit by gammametry

    International Nuclear Information System (INIS)

    The fluid dynamic behavior of riser of a cold flow model of a Fluid Catalytic Cracking Unit (FCCU) was investigated. The experimental data were obtained by the nuclear technique of gamma transmission. A gamma source was placed diametrically opposite to a detector in any straight section of the riser. The gas-solid flow through riser was monitored with a source of Americium-241 what allowed obtaining information of the axial solid concentration without flow disturbance and also identifying the dependence of this concentration profile with several independent variables. The MatLabR and StatisticaR software were used. Statistica tool employed was the Principal Components Analysis (PCA), that consisted of the job of the data organization, through two-dimensional head offices to allow extract relevant information about the importance of the independent variables on axial solid concentration in a cold flow riser. The variables investigated were mass flow rate of solid, mass flow rate of gas, pressure in the riser base and the relative height in the riser. The first two components reached about 98 % of accumulated percentage of explained variance. (author)

  3. 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

  4. 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.

  5. A study about the contribution of the α-β phase transition of quartz to thermal cycle damage of a refractory used in fluidized catalytic cracking units

    Directory of Open Access Journals (Sweden)

    A. H. A. Pereira

    2014-09-01

    Full Text Available The deterioration of refractories used in fluidized catalytic cracking units (FCC-units is responsible for high costs of maintenance for the petrochemical industry. This is commonly associated with coke deposition during the production of light hydrocarbons. However, other mechanisms responsible for causing damage may also occur, such as the generation of cracks by expansive phase transition. The aim of the work herein was to study the contribution of the a-b phase transition of quartz particles to the deterioration of a commercial aluminosilicate refractory used in a riser by the means of slow thermal cycles. Such damage may occur if the working temperature of the equipment fluctuates around the a-b transition temperature (573 °C. The current study considered the material with and without coke impregnation to evaluate the combined effect of coke presence and phase transition. To evaluate the damage, it was used the Young's modulus as a function of temperature by applying the Impulse Excitation Technique under controlled atmosphere. An equipment recently developed by the authors research group was applied. Specimens were prepared and submitted to slow thermal cycles of temperatures up to 500 °C and up to 700 °C, with a heating rate of 2 °C/min. Part of the specimens was previously impregnated with coke by a reactor using propen. To complete the evaluation, characterization by X-ray diffraction, as well as by dilatometry and scanning electron microscopy were performed. The findings of this study showed that the presence of quartz particles determine the thermo-mechanical behaviour of the material, as well as the thermocycling damage resistance. In spite of the fact that the a-b phase transition stiffens the material during the heating stage, it increases the damage by slow thermal cycling. The coke impregnation increases the resistance to slow thermal cycles, however it decreases the resistance to the damage evolution.

  6. Catalytic cracking process with vanadium passivation

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, J.V.; Jossens, L.W.

    1991-03-26

    This paper discusses a process for the catalytic cracking of metal-containing hydrocarbonaceous feedstock. It comprises contacting the feedstock under cracking conditions with a dual component catalyst composition. The catalyst composition comprises a first component comprising an active cracking catalyst; and a second component, as a separate and distinct entity, the second component comprising the following materials: a calcium and magnesium containing material selected from the group consisting of dolomite, substantially amorphous calcium magnesium silicate, calcium magnesium oxide, calcium magnesium acetate, calcium magnesium carbonate, and calcium magnesium subcarbonate; a magnesium containing material comprising a hydrous magnesium silicate; and a binder selected from the group consisting of kaolin, bentonite, montmorillonite, saponite, hectorite, alumina, silica, titania, zirconia, silica-alumina, and combinations thereof.

  7. 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

  8. 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.)

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Using spent fluid catalytic cracking (FCC catalyst as pozzolanic addition — a review

    Directory of Open Access Journals (Sweden)

    Nancy Torres Castellanos

    2010-06-01

    Full Text Available Spent fluid catalytic cracking (FCC catalyst is an oil industry by product from fluidised-bed catalytic cracking units. This residue is mainly formed by an active component (faujasite type zeolite Y in an amorphous aluminosilicate matrix. It mainly consists of up to 90% silica and alumina. This paper reports an extensive literature review regarding the characterisation and mechanical and durability properties of mortar and concrete added to this material. FCC has been studied lately due to its pozzolanic characteristics and the good performance of concrete mixtures using FCC as cement replacement.

  16. 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

  17. 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.

  18. 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)

  19. 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

  20. Catalytic Cracking of Used Palm Oil using Composite Zeolite

    International Nuclear Information System (INIS)

    The rapid expansion of human society implies greater energy demand and environmental issues. In face of depletion energy resources, research is being carried out widely in order to convert the plant oil into biofuel. In this research, the production of liquid biofuels via catalytic cracking of used palm oil in the presence of composite zeolite was studied. The performance of composite zeolite of different properties in the reaction has been evaluated. The catalytic cracking reactions were carried out in a batch reactor at reaction temperature of 350 degree Celsius for an hour. In the present study, adjusting the ratio of meso porous coating to microporous zeolite and magnesium loading on composite zeolite catalyst were found to be able to increase the gasoline fraction and overall conversion of the reaction. (author)

  1. 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.

  2. 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.

  3. 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 ...

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. 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

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

    OpenAIRE

    Yulong Wang; Ruifang Zhao; Chun Zhang; Guanlong Li; Jing Zhang; Fan Li

    2014-01-01

    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...

  10. 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.

  11. Catalytic cracking of iso-hexene over sapo-34 catalyst

    International Nuclear Information System (INIS)

    The catalytic cracking of model feed compound, iso-hexene (2-methyl-1-pentene) was experimentally studied over 100% pure SAPO-34 zeolite catalyst. The critical focus was given to obtain maximum propylene selectivity. The product distributions were analyzed at temperature between 450-600 degree C. time-on-stream (TOS) from 1 to 5 min. and at WHSV = 7.9 h/sub -1/ The reaction behavior was quantified on both direct and indirect carbenium ion mechanisms owing to catalyst's small pore diameter with respect to 2-methyl-l-pentene kinetic diameter. The propylene yield and selectivity obtained was 41.2% and 43.1% respectively. with higher overall olefins selectivity 90.3%. The small pore size and week surface acid sites of 1000 percent pure SAPO-34 catalyst were found to be suitable for light olefins production and eliminate chances of bimolecular reactions. It was observed that both conversion and selectivity were strongly effected by TOS, as coke precursors become dominant and deactivate catalyst at higher TOS. (author)

  12. 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

  13. MODELLING AND PARAMETER ESTIMATION IN REACTIVE CONTINUOUS MIXTURES: THE CATALYTIC CRACKING OF ALKANES. PART I

    OpenAIRE

    F. C. PEIXOTO; J. L. de Medeiros

    1999-01-01

    Fragmentation kinetics is employed to model a continuous reactive mixture. An explicit solution is found and experimental data on the catalytic cracking of a mixture of alkanes are used for deactivation and kinetic parameter estimation.

  14. 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.

  15. Increasing Octane Value in Catalytic Cracking of n-Hexadecane with Addition of *BEA Type Zeolite

    OpenAIRE

    Iori Shimada; Ryoichi Imai; Yoshinori Hayasaki; Hiroshi Fukunaga; Nobuhide Takahashi; Toru Takatsuka

    2015-01-01

    In this study, multifunctional catalysts were developed by adding *BEA or MFI zeolite with high Si/Al ratio to a residual fluidized catalytic cracking (RFCC) catalyst and tested in the catalytic cracking of n-hexadecane, which is a heavy crude oil model compound, for the purpose of increasing the octane value of produced gasoline under the strong hydrogen transfer activity of the RFCC catalyst. Reaction products analysis revealed that the addition of *BEA zeolite to the RFCC catalyst increase...

  16. 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.

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

    International Nuclear Information System (INIS)

    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. (authors)

  18. IFP solutions for revamping catalytic reforming units

    Energy Technology Data Exchange (ETDEWEB)

    Gendler, J.L. [HRI, Inc., Princeton, NJ (United States); Domergue, B.; Mank, L. [Inst. Francais du Petrole, Rueil Malmaison (France)

    1996-12-01

    The decision-making process for the refiner considering a revamp of a catalytic reforming unit comprises many factors. These may be grouped in two broad areas: technical and economic. This paper presents the results of a study performed by IFP that illustrates catalytic reforming unit revamp options. Three IFP processes are described and operating conditions, expected yields, and economic data are presented. The following options are discussed: base case Conventional, fixed-bed, semi-regenerative catalytic reformer; Case 1--revamp using IFP Dualforming technology; Case 2--revamp using IFP Dualforming Plus technology; and Case 3--revamp to IFP Octanizing technology. The study illustrates various options for the refiner to balance unit performance improvements with equipment, site, and economic constraints. The study was performed assuming design feedrate of 98.2 tons/hour (20,000 BPSD) in all cases. Because of the increased need for octane in many refineries, the study assumed that operating severity was set at a design value of 100 research octane number clear (RON). In all of the cases in this study, it was assumed that the existing recycle compressor was reused. Operating pressure differences between the cases is discussed separately. Also, in all cases, a booster compressor was included in order to return export hydrogen pressure to that of the conventional unit.

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

    OpenAIRE

    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. Steam cracking maximizes ethylene formation and propylene is produced only as a secondary product. The faster increase in demand of propylene than that of ethylene makes steam cracking a less attracti...

  20. 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.

  1. Packed-bed catalytic cracking of oak derived pyrolytic vapors

    Science.gov (United States)

    Catalytic upgrading of pyrolysis vapors derived from oak was carried out using a fixed-bed catalytic column at 425 deg C. The vapors were drawn by splitting a fraction from the full stream of vapors produced at 500 deg C in a 5 kg/hr bench-scale fast pyrolysis reactor system downstream the cyclone s...

  2. Geopolymers based on spent catalyst residue from a fluid catalytic cracking (FCC) process

    OpenAIRE

    RODRIGUEZ MARTINEZ, ERICH DAVID; Bernal, Susan A.; Provis, John L.; Gehman, John D.; Monzó Balbuena, José Mª; Paya Bernabeu, Jorge Juan; Borrachero Rosado, María Victoria

    2013-01-01

    This paper assesses the use of alkali activation technology in the valorization of a spent fluid catalytic cracking (FCC) catalyst, which is a residue derived from the oil-cracking process, to produce geopolymer binders. In particular, the effects of activation conditions on the structural characteristics of the spent catalyst- based geopolymers are determined. The zeolitic phases present in the spent catalyst are the main phases participating in the geopolymerization reaction, which is ...

  3. 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.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.)

  10. Pulsed-field gradient nuclear magnetic resonance study of transport properties of fluid catalytic cracking catalysts

    Czech Academy of Sciences Publication Activity Database

    Kortunov, P.; Vasenkov, S.; Kärger, J.; Fé Elía, M.; Perez, M.; Stöcker, M.; Papadopoulos, G. K.; Theodorou, D.; Drescher, B.; McElhiney, G.; Bernauer, B.; Krystl, V.; Kočiřík, Milan; Zikánová, Arlette; Jirglová, Hana; Berger, C.; Gläser, R.; Weitkamp, J.; Hansen, E. W.

    2005-01-01

    Roč. 23, č. 2 (2005), s. 233-237. ISSN 0730-725X Grant ostatní: TROCAT project - European Community(DE) G5RD-CT-2001-00520 Institutional research plan: CEZ:AV0Z40400503 Keywords : pulsed-field gradient * nuclear magnetic resonance * fluid catalytic cracking catalyst Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.361, year: 2005

  11. 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...

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

    OpenAIRE

    L. Soriano); Monzó, J.; Borrachero, M. V.; Payá, J.

    2009-01-01

    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...

  13. 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...

  14. Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil to Liquid Fuels

    Directory of Open Access Journals (Sweden)

    Wara Dyah Pita Rengga

    2015-03-01

    Full Text Available Reaction kinetics of catalytic cracking of rubber seed oil to liquid fuels has been investigated. The reac-tion was performed with sulfuric acid as catalyst at temperatures of 350-450 oC and the ratio of oil-catalyst of 0-2 wt.% for 30-90 minutes. Kinetics was studied using the model of 6-lump parameters. The parameters were rubber seed oil, gasoline, kerosene, diesel, gas, and coke. Analysis of experimen-tal data using regression models to obtain reaction rate constants. Activation energies and pre-exponential factors were then calculated based on the Arrhenius equation. The simulation result illus-trated that the six-lump kinetic model can well predict the product yields of rubber seed oil catalytic cracking. The product has high selectivity for gasoline fraction as liquid fuel and the smallest amount of coke. The constant indicates that secondary reactions occurred in diesel products compared to gaso-line and kerosene. The predicted results indicate that catalytic cracking of rubber seed oil had better be conducted at 450 oC for 90 minutes using 0.5 wt.% catalyst. © 2015 BCREC UNDIP. All rights reservedReceived: 3rd December 2013; Revised: 5th December 2014; Accepted: 7th December 2014How to Cite: Rengga, W.D.P., Handayani, P.A., Kadarwati, S., Feinnudin, A.(2015. Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil  to Liquid Fuels. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 50-60. (doi:10.9767/bcrec.10.1.5852.50-60Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.5852.50-60

  15. 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...

  16. 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.

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

    International Nuclear Information System (INIS)

    Highlights: • Waste resources such as WTO and waste fly ash have been effectively harnessed. • WTO has been catalytically cracked using fly ash catalyst for the first time. • Characteristics of a diesel engine were evaluated for CCWTO-diesel blends. • BTE and PHRR were increased by 7.4% and 13.2%, respectively, for CCWTO 50. • HC and CO emissions were reduced for CCWTO 50 with the increased NOX emission. - Abstract: 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

  18. Catalytic Cracking Palm Fatty Acid Distillate (PFAD) Dengan Katalis Zeolit (ZSM-5) Menjadi Biofuel

    OpenAIRE

    Muliani **

    2016-01-01

    Biofuel such as biodiesel, biogasoline is very interested for researchers to develop environmentally friendly and is also free of sulphur and nitrogen. It is biodegradable, non-toxic, and typically produces about 60% less carbon dioxide (CO2) emissions from petroleum-based diesel. The main problems in producing biofuels with cracking is the high cost that can be reduced by using cheaper raw materials and catalysts. Therefore, in this study of biofuels obtained by catalytic c...

  19. Increasing Octane Value in Catalytic Cracking of n-Hexadecane with Addition of *BEA Type Zeolite

    Directory of Open Access Journals (Sweden)

    Iori Shimada

    2015-04-01

    Full Text Available In this study, multifunctional catalysts were developed by adding *BEA or MFI zeolite with high Si/Al ratio to a residual fluidized catalytic cracking (RFCC catalyst and tested in the catalytic cracking of n-hexadecane, which is a heavy crude oil model compound, for the purpose of increasing the octane value of produced gasoline under the strong hydrogen transfer activity of the RFCC catalyst. Reaction products analysis revealed that the addition of *BEA zeolite to the RFCC catalyst increased the yields of olefins and multi-branched paraffins, which resulted in improvement of the octane value without sacrificing gasoline yield. On the contrary, the addition of MFI zeolite decreased the gasoline yield because it cracks the gasoline range olefins into LPG range olefins. In general, it is difficult to increase the yield of multi-branched molecules because the multi-branched molecule is more easily cracked than linear molecules. Our results suggest the possibility for the selective acceleration of isomerization reaction by the addition of less acidic *BEA zeolite to the RFCC catalyst.

  20. 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.

  1. 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)

  2. Improved propene yields from catalytic cracking. The potential of medium-pore zeolites as additives

    Energy Technology Data Exchange (ETDEWEB)

    Bager, Florian; Nieves Lopez Salas, Maria de las; Ernst, Stefan [Kaiserslautern Univ. (Germany). Dept. of Chemistry, Chemical Technology

    2012-06-15

    Light olefins, especially ethene and propene, are important building blocks in the petrochemical industry. Today, the major part of propene is produced via steam cracking and, to a smaller extent, obtained as a by-product from fluid catalytic cracking (FCC). The standard catalyst in the FCC process still is zeolite Y, but zeolite ZSM-5 is used since many years as an additive to increase the yield of light olefins, especially of propene. The aim of our study is to investigate the potential of medium-pore zeolites different from ZSM-5 as additives for FCC catalysts. Therefore, a series of ten-membered ring zeolites, viz. ZSM-22 (TON), ZSM-23 (MTT), EU-1 (EUO) and ZSM-5 (MFI) as reference material were synthesized under hydrothermal conditions and modified by ion exchange to obtain the Broensted-acid forms. The activity and selectivity of these catalysts in the catalytic cracking of n-octane as a model hydrocarbon were studied in a continuously operated fixed-bed flow-type reactor. The obtained results clearly demonstrate the effect of the pore architecture on the n-octane conversion and the product distribution. Compared with the three-dimensional zeolite ZSM-5, both one-dimensional zeolites lacking any intracrystalline cavities, viz. ZSM-22 and ZSM-23, exhibit a remarkable increase of monomolecular cracking, resulting in an increasing selectivity to unsaturated products. Introducing large cavities in the pore system, i. e. as in the case of zeolite EU-1, enhances the conversion in particular at lower reaction temperatures. However, these large cavities offer more space for the formation of large transition states required for the classical bimolecular cracking mechanism. As a result, a decreasing selectivity to olefins(including propene) and an increasing amount of aromatics is observed. (orig.)

  3. 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.

  4. 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.

  5. 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.

  6. Pozzolanic Reaction Rate of Fluid Catalytic Cracking Residue (FC3R) in Cement Pastes

    OpenAIRE

    Paya Bernabeu, Jorge Juan; Monzó Balbuena, José Mª; Borrachero Rosado, María Victoria; SERGIO VELAZQUEZ RODRIGUEZ

    2013-01-01

    Fluid catalytic cracking catalyst residue (FC3R) is a waste material generated in the petroleum industry. Previous research has shown that FC3R exhibits excellent pozzolanic properties in Portland cement mixtures. The pozzolanic activity of FC3R was studied by means of thermogravimetric analysis (measurement of lime fixation) and cold hydrochloric acid treatment (quantification of FC3R reacted). A water/binder ratio of 0.40 was used in the study in the preparation of a control paste (without ...

  7. Pembuatan Biofuel dari Palm Olein dengan Proses Thermal Catalytic Cracking Menggunakan Katalis ZSM-5

    OpenAIRE

    Gusti, Oktris Novali

    2016-01-01

    Depletion of fossil energy led to an interest in the development of renewable fuels from vegetable oils. Indonesia is the largest palm oil producer in the world, where palm oil can be converted into biofuels such as biogasoline, kerosene and biodiesel is environmentally friendly and free of the content of nitrogen and sulfur through catalytic cracking process. In this research palm olein was used as feedstock with the catalyst used is ZSM-5, which has a surface area of 425 m2 / g and Si / Al ...

  8. 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.

  9. 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)

  10. 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.

  11. 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.

  12. Electron beam application for regeneration of catalysts used in refinery cracking units

    International Nuclear Information System (INIS)

    A catalyst is a substance that alters the rate of a reaction. The process of catalysis is essential to the modern day manufacturing industry, mainly in Fluid Catalytic Cracking Process (FCC) units. However, long-term exploitation of oil and gas processing catalysts leads to formation of carbon-and sulfur-containing structures of coke and dense products on the catalyst surface. They block reactive catalyst sites and reduce the catalytic activity. The main advantage of radiation processing by electron beam (EB) and gamma rays is chain cracking reaction in crude oil. Otherwise, under exposure to ionic radiation, considerable structure modification of equilibrium silica-alumina catalyst from FCC process may occur, in addition to the removal of impurities. The conditions applied in the irradiation range (20-150 kGy) of gamma rays and electron beam were not sufficient to alter the structure of the catalyst, whether for removal of the contaminant nickel, a major contaminant of the FCC catalyst, either to rupture of the crystalline structure either for the future reutilization of chemical elements. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRFS) analysis were used to characterize and evaluate effects of radiation processing on equilibrium catalysts purification. To evaluate and comprehend the reactive catalyst sites, Scanning Electron Microscopy (SEM) and particle size distribution analyses were carried out. (author)

  13. 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.

  14. Catalytic cracking of crude bio-oil from glycerol-assisted liquefaction of swine manure

    International Nuclear Information System (INIS)

    Highlights: • Bio-oil from glycerol-assisted liquefaction of swine manure was cracked over zeolite. • 30-Min cracking on 5% catalyst at 400 °C yielded 46.1% bio-oil with 62.5% recovered energy. • 30-Min cracking on 5% catalyst at 400 °C removed 55.74% oxygen in the crude bio-oil. • The heating value and viscosity of the upgraded bio-oil were 41.4 MJ/kg and 3.6 cP. • Long chain acid methyl esters were cracked into alkanes, alkenes and short chain esters. - Abstract: The crude bio-oil produced from the glycerol-assisted liquefaction of swine manure which had large amount of long chain esters, was upgraded by thermal cracking over a modified zeolite catalyst. The effects of thermal cracking temperature (350–425 °C), reaction time (15–60 min) and catalyst loading (0–10 wt%) on the yield and quality of the upgraded oil were analyzed. The yield of upgraded bio-oil decreased with the increase of reaction temperature, reaction time and catalyst loading, but the viscosity, heating value and composition of the upgraded bio-oil became more desirable. Taking into the consideration both the yield and quality of the upgraded bio-oil, the optimal thermal cracking could be achieved over 5 wt% catalyst at 400 °C for 30 min. Under this condition, the yield of upgraded bio-oil was 46.14 wt% of the crude bio-oil, and 62.5% of the energy stored in the crude bio-oil was recovered. The oxygen content of the upgraded bio-oil was 15.04%, which was less than half of the original value of 33.98%. The viscosity of the upgraded bio-oil was 3.6 cP, compared with 188.9 cP for the crude bio-oil. The heating value of the upgraded bio-oil was 41.4 MJ/kg, compared with 30.54 MJ/kg for the crude bio-oil. Both the viscosity and heating value of the upgraded bio-oil were comparable to those of commercial diesel. The GC–MS analysis showed that the catalytic upgrading resulted in the increased cracking of long-chain acid methyl esters (such as hexadecanoic acid methyl ester

  15. 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.

  16. Catalytic cracking of tar in biomass pyrolysis gas in the presence of calcined dolomite

    International Nuclear Information System (INIS)

    The possibility of decreasing the tar content of the fuel gas obtained by biomass pyrolysis was studied. Pyrolysis of mixed hardwood chips was carried out in a laboratory-scale cracking reactor using a dolomite catalyst, which showed a high catalytic activity. The effects of reaction variables such as temperature, and amount of catalyst and steam, were studied. The overall effect of the dolomite is to increase the gas yield by decreasing the tar yield. The dolomite and the steam used seem to affect the amount of naphthalene produced. By adjusting both the amounts of catalyst and steam, the amounts of naphthalene (13 mg/kg of dry biomass) and tar (164 mg/kg) were decreased significantly. The yields of hydrogen, CO and CO2 depended on the steam to biomass weight ratio in the range of 0 to 0.6 kg/kg. 18 refs., 8 figs., 5 tabs

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Catalytic cracking of vegetable oil with metal oxides for biofuel production

    International Nuclear Information System (INIS)

    Highlights: • Biofuel was synthesized from vegetable oil by catalytic cracking. • Performance of six different metal catalysts was studied. • Influence of temperature and reaction time on the process was evaluated. • Methyl and ethyl esters are the major components of the biofuel synthesized. - Abstract: This study presents the utilization of metal oxides for the biofuel production from vegetable oil. The physical and chemical properties of the diesel-like products obtained, and the influence of reaction variables on the product distribution were investigated. Six different metal oxides (Co3O4, KOH, MoO3, NiO, V2O5, and ZnO) were employed as catalysts and the results indicated that the metal oxides are suitable for catalyzing the conversion of oil into organic liquid products (OLPs). The maximum conversion (87.6%) was obtained with V2O5 at 320 °C in 40 min whereas a minimum conversion (55.1%) was obtained with MoO3 at 390 °C in 30 min. The physical characteristics of the product obtained (density, specific gravity, higher heat value, flash point and kinematic viscosity), were in line with ASTM D6751 (B100) standards. The hydrocarbons majorly present in the product were found to be methyl and ethyl esters. Furthermore, OLPs obtained were distilled and separated into four components. The amount of light hydrocarbons, gasoline, kerosene and heavy oil like components obtained were 18.73%, 33.62%, 24.91% and 90.93%, respectively

  8. The current status and perspectives of biofuel production via catalytic cracking of edible and non-edible oils

    International Nuclear Information System (INIS)

    Biofuel development has gained the attention of researchers in recent years owing to the rate of depletion of fossil fuels. Several processes are currently employed in the conventional production of different biofuels: the production of biodiesel is catalytically performed either through the transesterification of triglycerides using alcohol or the deoxygenative ecofining of triglycerides in a non-alcohol environment; bio-oil is produced by the pyrolysis of biomass; bio-ethanol is produced by the fermentation of sugars obtained from starch or cellulosic based biomass, while bio-gasoline is produced from the catalytic cracking of triglycerides. Owing to the enormous dependency of transport vehicles running on gasoline engines, the development of bio-gasoline may well reduced the dependence of the fuel market on fossil fuels. The present article summarizes recent progresses and future prospects of biofuel production via catalytic cracking technology. This technology can be implemented in current petroleum refineries with minor modifications. However, reactor design and catalyst choice are important issues and have to be addressed before successful implementation of this technology in commercial ventures.

  9. 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.

  10. Spent fluid catalytic cracking catalyst (FCC) applications in the preparation of hydraulic binders: Pozzolanic properties study

    Science.gov (United States)

    Velazquez Rodriguez, Sergio

    At the present work the replacement of Portland cement in pastes and mortars by spent fluid catalytic cracking catalyst (FCC) is studied. The study has been focused in four physicochemical characterization, hydrated lime/catalyst and cement/catalyst pastes and mortars studies, and environmental impact aspects. The FCC characterization establishes that it is a silicoaluminate, having a mainly amorphous structure, with a great specific surface, and that is necessary its mechanical activation (grinding) to obtain a pozzolanic behaviour material. The reactivity was studied by: thermogravimetry, X ray diffractometry, aqueous media electrical conductivity measurements, Fourier transform infrared spectroscopy, scanning electron microscopy, mechanical strength development evaluation and cementing effectiveness k-factor evaluation. The very high pozzolanic activity of the material has been demonstrated, besides that this reactivity has been superior to others similar products such as the metakaolin. The products formed in the hydration, pozzolanic and hydration catalysis of cement reactions have been studied, comparing the reactivity characteristics with others better known pozzolans. The nature of the reaction products between FCC and hydrated lime is similar to the ones formed by the metakaolin, being fundamentally calcium silicate hydrates and hydrated gehlenite, and their formation allow to obtain microstructures with higher mechanical strength. The possibility of preparation materials containing cement/FCC with improved mechanical strength and drying shrinkage has been demonstrated, compared to homologous materials without ground FCC. The optimal FCC dosage for the lime fixation maximization has been determined, showing a pozzolanic behaviour similar to metakaolin, nevertheless very superior to others studied pozzolans, behaviour that is improved with the aid of certain chemical activators, and with the increasing of the curing temperature. Measurements of electrical

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

    OpenAIRE

    Payá, J.; Garcés, P.; Zornoza, E.

    2008-01-01

    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 ste...

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. DRASTIC ENHANCEMENT OF PROPENE YIELD FROM 1-HEXENE CATALYTIC CRACKING USING A SHAPE INTENSIFIED MESO-SAPO-34 CATALYST

    Directory of Open Access Journals (Sweden)

    ZEESHAN NAWAZ

    2009-12-01

    Full Text Available A shape intensified Meso-SAPO-34 catalyst was designed and used to improve the yield and selectivity of propene from 1-hexene cracking. The propene was produced with an optimal selectivity of 73.9 wt.% with high feed conversion 98.2 wt.% at 14 per hour WHSV. Robust exponential control of the stereochemistry was observed over the Meso-SAPO-34 shape selective catalyst’s cracking. The influence of the operating parameters on 1-hexene catalytic cracking, such as reaction temperature, time-on-stream effect on product distribution and conversion variations were systematically studied. The yield of propene and conversion rapidly increased with the reaction temperature, until 575oC. Shape intensification and topological integration of SAPO-34 increases the diffusion opportunities for feed, and this phenomenon was found to be responsible for drastic increase in 1-hexene conversion and propene yield. One other reason for this increase is the suppression of surface reactions (isomerization and hydride transfer owing to better diffusion opportunities. About 55 wt.% propene yield and higher total olefins content was achieved over Meso-SAPO-34.

  18. 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...

  19. 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...... higher stiffness of the damaged material. The damage in the composites begins by fibre breakage, which causes the interface damage, followed by matrix cracking....

  20. 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.

  1. 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...

  2. Metallurgical investigation of cracking of the guide tube support pins at Vogtle unit 1

    International Nuclear Information System (INIS)

    This paper summarizes the findings of a metallurgical investigation conducted to establish the mechanism and cause of cracking of the Inconel X-750, 'Rev. A' guide tube support pins at Vogtle Unit 1 Station. The investigation was centered on five randomly selected pins and one field fractured pin. The examinations included surface examinations, nondestructive examinations, metallographic examinations, fractographic examinations, chemistry evaluations and hardness measurements. The overall results of the investigation showed that the observed cracking in the Vogtle 1 pins occurred by Primary Water Stress Corrosion Cracking (PWSCC). Stress enhancement due to a geometric discontinuity at the thread root and the shank to shoulder radius on the outside diameter surface contributed to the crack initiation. The pin material was conformed to be to the Inconel X-750, 'Rev. A' specification. (authors)

  3. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2010-10-01

    Full Text Available Research on synthesis and characterization of ZrO2-Montmorillonit and its application as catalyst in heavy fraction of crude oil (HFCO conversion has been investigated. Synthesis of catalyst was done by pillarization of ZrO2 into silicate interlayer of montmorillonite structure. The success in synthesis is shown by XRD and BET surface area measurement in that basal spacing d001 was increase after pillarization. Activity test of material was showed that ZrO2 dispersion affected catalytic activity in liquid production and the activity was increased asn increasing temperature in the range of 473K-673K. Composition of liquid product indicated that ZrO2-Montmorillonit tend to produce kerosene related to metal oxide distribution in synthesis. © 2008 BCREC UNDIP. All rights reserved.[Received: 3 June 2008, Accepted: 15 July 2008][How to Cite: I. Fatimah, K. Wijaya, K. H. Setyawan. (2008. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 9-13.  doi:10.9767/bcrec.3.1-3.7118.9-13][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.3.1-3.7118.9-13 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7118

  4. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil

    Directory of Open Access Journals (Sweden)

    Khoirul Himmi Setyawan

    2008-04-01

    Full Text Available Research on synthesis and characterization of ZrO2-Montmorillonit and its application as catalyst in heavyfraction of crude oil (HFCO conversion has been investigated. Synthesis of catalyst was done by pillarizationof ZrO2 into silicate interlayer of montmorillonite structure. The success in synthesis is shown by XRDand BET surface area measurement in that basal spacing d001 was increase after pillarization. Activitytest of material was showed that ZrO2 dispersion affected catalytic activity in liquid production and the activitywas increased asn increasing temperature in the range of 473K-673K. Composition of liquid productindicated that ZrO2-Montmorillonit tend to produce kerosene related to metal oxide distribution in synthesis. © 2008 BCREC UNDIP. All rights reserved.[Received: 3 June 2008, Accepted: 15 July 2008][How to Cite: I. Fatimah, K. Wijaya, K. H. Setyawan. (2008. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 9-13. doi:10.9767/bcrec.3.1-3.17.9-13

  5. 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...

  6. 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

  7. 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.

  8. 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。

  9. 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...

  10. 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

  11. Crocodile head scales are not developmental units but emerge from physical cracking.

    Science.gov (United States)

    Milinkovitch, Michel C; Manukyan, Liana; Debry, Adrien; Di-Poï, Nicolas; Martin, Samuel; Singh, Daljit; Lambert, Dominique; Zwicker, Matthias

    2013-01-01

    Various lineages of amniotes display keratinized skin appendages (feathers, hairs, and scales) that differentiate in the embryo from genetically controlled developmental units whose spatial organization is patterned by reaction-diffusion mechanisms (RDMs). We show that, contrary to skin appendages in other amniotes (as well as body scales in crocodiles), face and jaws scales of crocodiles are random polygonal domains of highly keratinized skin, rather than genetically controlled elements, and emerge from a physical self-organizing stochastic process distinct from RDMs: cracking of the developing skin in a stress field. We suggest that the rapid growth of the crocodile embryonic facial and jaw skeleton, combined with the development of a very keratinized skin, generates the mechanical stress that causes cracking. PMID:23196908

  12. A 25 kWe low concentration methane catalytic combustion gas turbine prototype unit

    International Nuclear Information System (INIS)

    Low concentration methane, emitted from various industries e.g. coal mines and landfills into atmosphere, is not only an important greenhouse gas, but also a wasted energy resource if not utilized. In the past decade, we have been developing a novel VAMCAT (ventilation air methane catalytic combustion gas turbine) technology. This turbine technology can be used to mitigate methane emissions for greenhouse gas reduction, and also to utilize the low concentration methane as an energy source. This paper presents our latest research results on the development and demonstration of a 25 kWe lean burn catalytic combustion gas turbine prototype unit. Recent experimental results show that the unit can be operated with 0.8 vol% of methane in air, producing about 19–21 kWe of electricity output. - Highlights: • A novel low concentration methane catalytic turbine prototype unit was developed. • The 25 kWe unit can be operated with ∼0.8 vol.% CH4 in air with 19–21 kWe output. • A new start-up method was developed for the prototype unit

  13. 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.)

  14. 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

  15. Catalytic cracking apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Skraba, F.W.

    1987-07-21

    This patent describes an apparatus comprising: (a) a catalyst lift pit having an upper end, a lower end, and a generally cylindrical sidewall having an interior surface defining a first diameter; (b) a riser-reactor connected to the upper end of the lift pot, the riser-reactor having a mouth defining a second diameter where it connects to the lift pot which is smaller than the lift pot first diameter; (c) a plug member extending axially into the lift pot from the lower end of the lift pot, the plug member being generally rotationally symmetric about its longitudinal axis and having an upper end surface which faces the mouth of the riser-reactor, the lift pot, the riser-reactor and the plug.

  16. 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.

  17. 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)

  18. 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.

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

    International Nuclear Information System (INIS)

    A series of HZSM-5/MCM-41 composite molecular sieves (HZM-Ns (x)) were prepared by employing nano-ZSM-5 zeolites with the SiO2/Al2O3 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, N2 adsorption–desorption measurement, and NH3 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 SiO2/Al2O3 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 SiO2/Al2O3 ratio

  20. 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.

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

    Science.gov (United States)

    2010-07-01

    ... in 40 CFR 60.102 PM emissions must not the exceed 1.0 kilogram (kg) per 1,000 kg (1.0 lb/1,000 lb) of...-hour period. 2. Option 1: NSPS requirements not subject to the NSPS for PM in 40 CFR 60.102 PM... 2: PM limit not subject to the NSPS for PM in 40 CFR 60.102 PM emissions must not exceed 1.0...

  2. A novel "wastes-treat-wastes" technology: role and potential of spent fluid catalytic cracking catalyst assisted ozonation of petrochemical wastewater.

    Science.gov (United States)

    Chen, Chunmao; Yu, Ji; Yoza, Brandon A; Li, Qing X; Wang, Gang

    2015-04-01

    Catalytic ozonation is a promising wastewater treatment technology. However, the high cost of the catalyst hinders its application. A novel "wastes-treat-wastes" technology was developed to reuse spent fluid catalytic cracking catalysts (sFCCc) for the ozonation of petrochemical wastewater in this study. Multivalent vanadium (V(4+) and V(5+)), iron (Fe(2+) and Fe(3+)) and nickel (Ni(2+)) oxides that are distributed on the surface of sFCCc and poisoned FCC catalysts are the catalytic components for ozonation. The sFCCc assisted catalytic ozonation (sFCCc-O) of nitrobenzene indicated that the sFCCc significantly promoted hydroxyl radical mediated oxidation. The degradation rate constant of nitrobenzene in sFCCc-O (0.0794 min(-1) at 298 K) was approximately doubled in comparison with that in single ozonation (0.0362 min(-1) at 298 K). The sFCCc-O of petrochemical wastewater increased chemical oxygen demand removal efficiency by three-fold relative to single ozonation. The number of oxygen-containing (Ox) polar contaminants in the effluent (253) from sFCCc-O treatment decreased to about 70% of the initial wastewater (353). The increased oxygen/carbon atomic ratio and decreased number of Ox polar contaminants indicated a high degree of degradation. The present study showed the role and potential of sFCCc for catalytic ozonation of petrochemical wastewater, particularly in an advantage of the cost-effectiveness through "wastes-treat-wastes". PMID:25617869

  3. 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

  4. Stress corrosion cracking of HP turbine using bolts of 900 MW CP1 units

    International Nuclear Information System (INIS)

    Failures or cracks of HP turbine casing bolts of the 900 MW PWR units are due to stress corrosion in humid steam and in presence of chlorinated solvents used during maintenance operations or before the mounting of bolts. This phenomenon does not concern only the steel used (35 NCD6 or 28 CDV 5-08), for the phenomenon has been reproduced in laboratory on other steel qualities, more particularly the Z 12 CNDV 12-2 steel. This steel would present a better resistance to this type of corrosion at temperatures lower than 2500C. Action have been undertaken to avoid these problems: systematic control at each casing opening; cleaning of bolts and bores for turbines having presented the phenomenon; chlorinated products are prohibited; change of the joint which ensures tightness, utilization of the Z 12 CNDV 12-2 steel quality and, study of the increase of screwing to keep the joint tight

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. B reactor recirculation pump shaft crack: A case history Grand Gulf Nuclear Station Unit number-sign 1

    International Nuclear Information System (INIS)

    This case history documents the vibration response of the B Reactor Recirculation Pump at Grand Gulf Unit number-sign 1, during the first eleven days of May 1989, while a crack was propagating through the pump shaft in the general area of the hydrostatic bearing. The data presented in this paper was originally acquired by Grand Gulf personnel with an instrument grade tape recorder. The recorded data was later provided to Bently Nevada Corporation for analysis

  11. The forming of coke by catalytic cracking of black mineral oil by catalysts on the base of activated aluminium alloys

    International Nuclear Information System (INIS)

    The paper deals with an investigation in coke formation under black mineral oil reactions on oxide catalysts which care based on activated aluminium alloys containing 2-20% of active components of In and Ga. The coke yield is of extreme nature and depends on the content of active components in the catalyst composition. The application of thermogravimetric method shows that the oxidation of coke depositions after black mineral oil cracking proceeds in the same temperature range while after the steam-water treatment of coked catalysts the oxidation of coke deposition proceeds at higher temperatures with different temperature maximums which points to the inhomogeneity of coke depositions. It is shown that the catalyst phase composition changes significantly during the reaction under the effect of reaction mixture. 4 refs., 3 figs

  12. Destructive examination of a cracked alloy A-286 Vent Valve Jackscrew from the Oconee unit 1 nuclear station

    International Nuclear Information System (INIS)

    During the Fall 2012 refueling outage at Oconee Nuclear Station Unit 1, a reactor vessel internals video inspection revealed an abnormal condition on a reactor vessel vent valve. One of the Alloy A-286 jackscrews on this vent valve was visibly extended more than the other and bent, the lower section of the jackscrew threads were galled, and the lower barrel nuts were recessed. Furthermore, a circumferential crack-like indication was identified on the lower portion of the other jackscrew. The vent valve assembly was replaced during the refueling outage and the cracked portion of the jackscrew was submitted to Duke Energy's metallurgy lab for a failure mode determination. The failure investigation included metallography, scanning electronic microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and ASTM grain size determination. This paper determines that the failure most likely occurred from the resultant bending stress on the cracked jackscrew as the result of an impact load to the other jackscrew, and initiated and propagated by an intergranular stress corrosion cracking (IGSCC) mechanism. (authors)

  13. 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)

  14. 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)

  15. 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.

  16. 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 ...

  17. Alkali activated materials based on fluid catalytic cracking catalyst residue (FCC): Influence ofSiO2/Na2O and H2O/FCC ratio on mechanical strength and microstructure

    OpenAIRE

    Mitsuuchi Tashima, Mauro; AKASAKI, JORGE LUIS; Melges, J.L.P.; Soriano Martinez, Lourdes; Monzó Balbuena, José Mª; Paya Bernabeu, Jorge Juan; Borrachero Rosado, María Victoria

    2013-01-01

    Reuse of industrial and agricultural wastes as supplementary cementitious materials (SCMs) in concrete and mortar productions contribute to sustainable development. In this context, fluid catalytic cracking catalyst residue (spent FCC), a byproduct from the petroleum industry and petrol refineries, have been studied as SCM in blended Portland cement in the last years. Nevertheless, another environmental friendly alternative has been conducted in order to produce alternative binders with low C...

  18. An assessment of the pozzolanic activity of a spent catalyst from catalytic cracking using methods based on the measurement of the electrical conductivity and pH of suspensions with calcium hydroxide

    OpenAIRE

    Sergio Velázquez; JOSÉ M. MONZÓ; María V. Borrachero; Jordi Payá

    2014-01-01

    The pozzolanic activity of the spent catalyst produced by fluid catalytic cracking (FCC) has been studied by various methods in recent years. However, no quick and easy method has been reported for this activity based on the associated studies. In this work, the pozzolanic activity of a spent catalyst was investigated by measuring its electrical conductivity in aqueous suspensions of pozzolan/calcium hydroxide. The behavior of the FCC catalyst residue was compared to that of reactive and iner...

  19. 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.

  20. 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

  1. Heterogeneous kinetic modeling of the catalytic conversion of cycloparaffins

    Science.gov (United States)

    Al-Sabawi, Mustafa N.

    The limited availability of high value light hydrocarbon feedstocks along with the rise in crude prices has resulted in the international recognition of the vast potential of Canada's oil sands. With the recent expansion of Canadian bitumen production come, however, many technical challenges, one of which is the significant presence of aromatics and cycloparaffins in bitumen-derived feedstocks. In addition to their negative environmental impact, aromatics limit fluid catalytic cracking (FCC) feedstock conversion, decrease the yield and quality of valuable products such as gasoline and middle distillates, increase levels of polyaromatic hydrocarbons prone to form coke on the catalyst, and ultimately compromise the FCC unit performance. Although cycloparaffins do not have such negative impacts, they are precursors of aromatics as they frequently undergo hydrogen transfer reactions. However, cycloparaffin cracking chemistry involves other competing reactions that are complex and need much investigation. This dissertation provides insights and understanding of the fundamentals of the catalytic cracking of cycloparaffins using carefully selected model compounds such as methylcyclohexane (MCH) and decalin. Thermal and catalytic cracking of these cycloparaffins on FCC-type catalysts are carried out using the CREC Riser Simulator under operating conditions similar to those of the industrial FCC units in terms of temperature, reaction time, reactant partial pressure and catalyst-to-hydrocarbon ratio. The crystallite size of the supported zeolites is varied between 0.4 and 0.9 microns, with both activity and selectivity being monitored. Catalytic conversions ranged between 4 to 16 wt% for MCH and between 8 to 27 wt% for decalin. Reaction pathways of cycloparaffins are determined, and these include ring-opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. The yields and selectivities of over 60 and 140 products, formed during MCH and decalin

  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. 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.

  4. Investigation of intergranular stress corrosion cracking in the fuel pool at Three Mile Island Unit 1

    International Nuclear Information System (INIS)

    An intergranular stress corrosion cracking failure of 304 stainless steel pipe in 2000 ppM B as H3BO3 + H2O at 1000C has been investigated. Constant extension rate testing has produced an intergranular type failure in material in air. Chemical analysis was performed on both the base metal and weld material, in addition to fractography, EPR testing and optical microscopy in discerning the mode of failure. Various effects of Cl-, O2, and MnS are discussed. The results have indicated that the cause of failure was the severe sensitization coupled with probable contamination by S and possibly by Cl ions

  5. 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

  6. 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)

  7. 40 CFR Table 3 to Subpart Uuu of... - Continous Monitoring Systems for Metal HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... . . . You shall install, operate, and maintain a . . . 1. Subject to the NSPS for PM in 40 CFR 60.102 Any...: NSPS limits not subject to the NSPS for PM in 40 CFR 60.102 Any size Electrostatic precipitator or wet... CFR 60.102 a. Over 20,000 barrels per day fresh feed capacity Electrostatic precipitator...

  8. 40 CFR Table 2 to Subpart Uuu of... - Operating Limits for Metal HAP Emissions From Catalytic Cracking Units

    Science.gov (United States)

    2010-07-01

    ... . . . 1. Subject to the NSPS for PM in 40 CFR 60.102. Continuous opacity monitoring system. Not applicable Not applicable. 2. Option 1: NSPS requirements not subject to the NSPS for PM in 40 CFR 60.102... NSPS for PM in 40 CFR 60.102. a. Continuous opacity monitoring system. Electrostatic...

  9. 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

    ... operator shall use CPMS to measure and record the hourly average total power input and secondary voltage to... or operator shall determine and record the average coke burn-off rate and hours of operation for each... CO CEMS need not be installed if the owner or operator demonstrates that all hourly average...

  10. 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.

  11. 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

  12. 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.

  13. Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

    Directory of Open Access Journals (Sweden)

    Matthieu Jouffroy

    2014-10-01

    Full Text Available The capacity of two cavity-shaped ligands, HUGPHOS-1 and HUGPHOS-2, to generate exclusively singly phosphorus-ligated complexes, in which the cyclodextrin cavity tightly wraps around the metal centre, was explored with a number of late transition metal cations. Both cyclodextrin-derived ligands were assessed in palladium-catalysed Mizoroki–Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. The inability of both chiral ligands to form standard bis(phosphine complexes under catalytic conditions was established by high-pressure NMR studies and shown to have a deep impact on the two carbon–carbon bond forming reactions both in terms of activity and selectivity. For example, when used as ligands in the rhodium-catalysed hydroformylation of styrene, they lead to both high isoselectivity and high enantioselectivity. In the study dealing with the Mizoroki–Heck reactions, comparative tests were carried out with WIDEPHOS, a diphosphine analogue of HUGPHOS-2.

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

    International Nuclear Information System (INIS)

    A metal–organic framework [Co3(BDC)3(DMF)2(H2O)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 P21/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 [Co3(BDC)3(DMF)2(H2O)2]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 [Co3(BDC)3(DMF)2(H2O)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 P21/n space group based on Co(II)–carboxylate units. The catalytic oxidation of various olefins was effectively carried out with [Co3(BDC)3(DMF)2(H2O)2]n catalyst by TBHP as oxidant. - Highlights: • A metal–organic framework of [Co3(BDC)3(DMF)2(H2O)2] is prepared by hydrothermal method. • The [Co3(BDC)3(DMF)2(H2O)2]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

  15. Knuckle Cracking

    Science.gov (United States)

    ... Our Faculty Our Staff Rheumatology Specialty Centers Knuckle Cracking Q & A September 10, 2007 By Arthritis Center ... immediately. Question: Are there any side effects to cracking knuckles? There is no evidence that cracking knuckles ...

  16. 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

  17. 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

  18. 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.

  19. 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

    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 is...... 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...

  20. 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.

  1. 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.

  2. 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

  3. 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…

  4. 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...

  5. 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)

  6. 40 CFR Table 11 to Subpart Uuu of... - Requirements for Performance Tests for Organic HAP Emissions From Catalytic Cracking Units Not...

    Science.gov (United States)

    2010-07-01

    ..., or 2G in appendix A to part 60 of this chapter, as applicable. c. Conduct gas molecular weight... number of traverse ports. Method 1 or 1A in appendix A to part 60 of this chapter. Sampling sites must be...-hour averages computed from four or more data points equally spaced over each 1-hour period. 3....

  7. 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,...

  8. 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...

  9. Cracking behavior of structural slab bridge decks

    Science.gov (United States)

    Baah, Prince

    Bridge deck cracking is a common problem throughout the United States, and it affects the durability and service life of concrete bridges. Several departments of transportation (DOTs) in the United States prefer using continuous three-span solid structural slab bridges without stringers over typical four-lane highways. Recent inspections of such bridges in Ohio revealed cracks as wide as 0.125 in. These measured crack widths are more than ten times the maximum limit recommended in ACI 224R-01 for bridge decks exposed to de-icing salts. Measurements using digital image correlation revealed that the cracks widened under truck loading, and in some cases, the cracks did not fully close after unloading. This dissertation includes details of an experimental investigation of the cracking behavior of structural concrete. Prism tests revealed that the concrete with epoxy-coated bars (ECB) develops the first crack at smaller loads, and develops larger crack widths compared to the corresponding specimens with uncoated (black) bars. Slab tests revealed that the slabs with longitudinal ECB developed first crack at smaller loads, exhibited wider cracks and a larger number of cracks, and failed at smaller ultimate loads compared to the corresponding test slabs with black bars. To develop a preventive measure, slabs with basalt and polypropylene fiber reinforced concrete were also included in the test program. These test slabs exhibited higher cracking loads, smaller crack widths, and higher ultimate loads at failure compared to the corresponding slab specimens without fibers. Merely satisfying the reinforcement spacing requirements given in AASHTO or ACI 318-11 is not adequate to limit cracking below the ACI 224R-01 recommended maximum limit, even though all the relevant design requirements are otherwise met. Addition of fiber to concrete without changing any steel reinforcing details is expected to reduce the severity and extent of cracking in reinforced concrete bridge decks.

  10. 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.

  11. 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.

  12. 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)

  13. 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.

  14. Probabilistic modeling of crack networks in thermal fatigue

    International Nuclear Information System (INIS)

    Thermal superficial crack networks have been detected in mixing zone of cooling system in nuclear power plants. Numerous experimental works have already been led to characterize initiation and propagation of these cracks. The random aspect of initiation led to propose a probabilistic model for the formation and propagation of crack networks in thermal fatigue. In a first part, uniaxial mechanical test were performed on smooth and slightly notched specimens in order to characterize the initiation of multiple cracks, their arrest due to obscuration and the coalescence phenomenon by recovery of amplification stress zones. In a second time, the probabilistic model was established under two assumptions: the continuous cracks initiation on surface, described by a Poisson point process law with threshold, and the shielding phenomenon which prohibits the initiation or the propagation of a crack if this one is in the relaxation stress zone of another existing crack. The crack propagation is assumed to follow a Paris' law based on the computation of stress intensity factors at the top and the bottom of crack. The evolution of multiaxial cracks on the surface can be followed thanks to three quantities: the shielding probability, comparable to a damage variable of the structure, the initiated crack density, representing the total number of cracks per unit surface which can be compared to experimental observations, and the propagating crack density, representing the number per unit surface of active cracks in the network. The crack sizes distribution is also computed by the model allowing an easier comparison with experimental results. (author)

  15. 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)

  16. Method and apparatus for pyrolytically cracking hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Skraba, F.W.

    1992-06-09

    This patent describes a method for pyrolytically cracking a hydrocarbon vapor feedstock in a hydrocarbon pyrolysis unit to produce an olefinic hydrocarbon product. It comprises contacting a hydrocarbon vapor feedstock, then, cracking the hydrocarbon vapor feedstock in the presence of the vaporized water in a pyrolysis furnace to produce a furnace effluent stream comprised of an olefinic hydrocarbon product gas and the vaporized water.

  17. Catalytic upgrading of biomass pyrolysis vapours using faujasite zeolite catalysts

    International Nuclear Information System (INIS)

    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 route to improve the quality of bio-oil is to pyrolyse the parent biomass in the presence of a catalyst. This work investigates the influence of faujasite catalysts on the pyrolysis of pinewood. Pyrolysis process with Na-faujasite, Na0.2H0.8-faujasite, and H-faujasite (Na-FAU, Na0.2H0.8-FAU, and H-FAU) were carried out in a fixed-bed reactor at 500 °C. It is shown that, in the same condition, catalytic upgrading of pyrolysis vapour is superior to in-situ catalytic pyrolysis of biomass when it comes to quality of bio-oil. The yields of coke, gas and water increase while that of organic phase decreases proportional with the concentration of protons in catalysts. Compared to the other two catalysts, Na0.2H0.8-FAU removes the most oxygen from bio-oil, reduces amount of acids and aldehydes/ketones which result in a higher energy-contained and more stable oil with less corrosive property. However, the biggest contribution to the oxygen removal is via the formation of reaction water, which is not an optimum path. This leaves space for future development. -- Highlights: ► Upgrading of biomass pyrolysis vapours was carried out using faujasite catalysts. ► Catalytic upgrading of pyrolysis vapours is superior to in-situ catalytic pyrolysis of biomass. ► Optimization of the amount of Na+ and H+ in faujasites is important. ► Losing high-energy hydrogen via the formation of reaction water is a drawback

  18. 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...

  19. Crack propagation in rubber-like materials

    International Nuclear Information System (INIS)

    Crack propagation in rubber-like materials is of great practical importance but still not well understood. We study the contribution to the crack propagation energy (per unit area) G from the viscoelastic deformations of the rubber in front of the propagating crack tip. We show that G takes the standard form G(v,T) = G0[1+f(v,T)] where G0 is associated with the (complex) bond-breaking processes at the crack tip while f(v,T) is determined by the viscoelastic energy dissipation in front of the crack tip. As applications, we discuss the role of crack propagation for adhesion, rolling resistance and sliding friction for smooth surfaces, and for rubber wear. (topical review)

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Stress corrosion cracking and vibration corrosion cracking

    International Nuclear Information System (INIS)

    Under certain conditions of stress practically all metallic materials are subject to such cracking corrosion processes. They are much feared because as a rule they are not recognized until the damage - leakage of a container, fracture of a component part-occurs. They may belong to the category of either stress corrosion cracking or vibration corrosion cracking, depending on the different mechanisms of the damage process. As the denominations indicate, one constitutes the interaction between local corrosion attack and mainly static tensile stress (load stress and/or non-load stress) and the other a combination of varying mechanical stress over time and corrosion. Hydrogen-induced cracking is a special form of stress corrosion cracking characterized by trapping of atomic hydrogen in material and subsequent cracking owing to the interaction with mechanical stress. (orig./HP)

  5. 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.

  6. Gear Crack Propagation Investigation

    Science.gov (United States)

    1995-01-01

    Reduced weight is a major design goal in aircraft power transmissions. Some gear designs incorporate thin rims to help meet this goal. Thin rims, however, may lead to bending fatigue cracks. These cracks may propagate through a gear tooth or into the gear rim. A crack that propagates through a tooth would probably not be catastrophic, and ample warning of a failure could be possible. On the other hand, a crack that propagates through the rim would be catastrophic. Such cracks could lead to disengagement of a rotor or propeller from an engine, loss of an aircraft, and fatalities. To help create and validate tools for the gear designer, the NASA Lewis Research Center performed in-house analytical and experimental studies to investigate the effect of rim thickness on gear-tooth crack propagation. Our goal was to determine whether cracks grew through gear teeth (benign failure mode) or through gear rims (catastrophic failure mode) for various rim thicknesses. In addition, we investigated the effect of rim thickness on crack propagation life. A finite-element-based computer program simulated gear-tooth crack propagation. The analysis used principles of linear elastic fracture mechanics, and quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically via an automated remeshing scheme. Crack-tip stress-intensity factors were estimated to determine crack-propagation direction. Also, various fatigue crack growth models were used to estimate crack-propagation life. Experiments were performed in Lewis' Spur Gear Fatigue Rig to validate predicted crack propagation results. Gears with various backup ratios were tested to validate crack-path predictions. Also, test gears were installed with special crack-propagation gages in the tooth fillet region to measure bending-fatigue crack growth. From both predictions and tests, gears with backup ratios

  7. Methods for detecting fatigue cracks in gears

    International Nuclear Information System (INIS)

    A crack in the tooth root is the least desirable damage caused to gear units and it often causes failure of gear unit operation. For fault analyses presented in this article, gear units with real damages or faults produced on the basis of numerical simulations of real operating conditions are used; tests were carried out in a laboratory test plant. Damages in gear units can be identified by monitoring vibrations. The influences of a crack in a single-stage gear unit on produced vibrations are presented. Significant changes in tooth stiffness are caused by a fatigue crack in the tooth root whereas, in relation to other faults, changes of other dynamic parameters are more expressed. Non-stationary signals are analysed, using the family of Time Frequency Analysis tools, which include Wavelets and Joint Time Frequency Analyses.

  8. 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.

  9. 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.

  10. Weld cracking - some examples

    International Nuclear Information System (INIS)

    The possible causes of cold cracking can be relatively clearly defined according to today's state of knowledge. By knowing these causes, it is possible to control the risk of cold cracking to the greatest extent; with the knowledge of the position and dimensions of these cracks, as well as the time of their occurence together with an optimization of the testing technique, the detection control of the cracking freedom can be almost considered as solved. (orig.)

  11. 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

  12. 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.

  13. A numerical investigation of the scale-up effects on flow, heat transfer, and kinetics processes of FCC units.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S. L.

    1998-08-25

    Fluid Catalytic Cracking (FCC) technology is the most important process used by the refinery industry to convert crude oil to valuable lighter products such as gasoline. Process development is generally very time consuming especially when a small pilot unit is being scaled-up to a large commercial unit because of the lack of information to aide in the design of scaled-up units. Such information can now be obtained by analysis based on the pilot scale measurements and computer simulation that includes controlling physics of the FCC system. A Computational fluid dynamic (CFD) code, ICRKFLO, has been developed at Argonne National Laboratory (ANL) and has been successfully applied to the simulation of catalytic petroleum cracking risers. It employs hybrid hydrodynamic-chemical kinetic coupling techniques, enabling the analysis of an FCC unit with complex chemical reaction sets containing tens or hundreds of subspecies. The code has been continuously validated based on pilot-scale experimental data. It is now being used to investigate the effects of scaled-up FCC units. Among FCC operating conditions, the feed injection conditions are found to have a strong impact on the product yields of scaled-up FCC units. The feed injection conditions appear to affect flow and heat transfer patterns and the interaction of hydrodynamics and cracking kinetics causes the product yields to change accordingly.

  14. Rare-earth elements in refinery cracking catalysts and fuel oils

    International Nuclear Information System (INIS)

    This paper reports that nearly all fluid catalytic-cracking units operating at refineries in the U.S. use zeolite catalysts to produce light-weight hydrocarbons, such as fuel oil and gasoline. These petroleum catalysts, typically containing 1-3% rare-earth elements (REEs), have accounted for an average of 40% of the U.S. consumption of REEs in the last 20 years. In a refinery, as the catalyst becomes deactivated (coked) it enters a regenerator, where the coke is oxidized and the flue gases are emitted to the atmosphere. Although refineries regenerate the catalysts many times, annual REE consumption suggests that portions of these catalysts are both discharged to the atmosphere and lost into refined fuels. Fuel combustion dispenses additional REE-containing catalysts into the atmosphere. It thus appears that the unique REE pattern creates an identifiable marker of aerosols containing the cracking catalysts. This study was conducted to determine trace-element composition of cracking catalysts and fuel oils in an effort to compare their REE patterns with emissions from OFPPs and refineries, and recent atmospheric measurements, as well as provide additional composition data for source identification and apportionments. As emission characterizations are difficult and expensive, results from this study can be applied to receptor modeling

  15. 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)

  16. 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.

  17. 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 a......-critical loads. Such information, which cannot be obtained experimentally, are needed in viscoelastic lifetime analysis.Finally, the question is considered whether or not fracture properties experimentally determined are real (genuine) material properties.......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...... (displacement) respectively of material considered. The practical applicability of the two models is limited such that predicted strength sigma_CR must be less than sigma_L/3, which corresponds to an assumption that fictitious cracks are much smaller than real crack lengths considered. The reason for this...

  18. 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.

  19. Repair procedure used in removing corroded pits in the distillation towers of the Getulio Vargas Refinery Unit 2100

    Energy Technology Data Exchange (ETDEWEB)

    Lordelos, H.M.; Santin, J.L.

    1977-07-01

    A description is given of the corrosion pits on ASTM A240, Type 405 steel cladded to carbon steel plates used in Petroleo Brasileiro S.A.'s Getulio Vargas Refinery Unit 2100 distillation towers; the repair procedure used, including sand blasting of the corroded surfaces, grinding of the pits, and welding of those pits whose depth was above a maximum limit, and the use of liquid penetrant to check the repairs made; and hydrostatic testing of the T2201 catalytic cracking unit, which used also cladded metals and on which the pits were much smaller in size and number than those on the distillation units.

  20. Eliminating cracking during drying

    OpenAIRE

    Jin, Qiu; Tan, Peng; Schofield, Andrew B.; Xu, Lei

    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 achiev...

  1. Crack identification in elasticity

    International Nuclear Information System (INIS)

    Crack and defect, e.g. hole, identification in elasticity, is formulated as an output optimization problem, where predictions of a suitably parametrized mechanical model are compared with measured data. For the mechanical part the elastostatic analysis is done by the boundary element method, including hypersingular boundary elements for the cracks. In addition, unilateral contact effects along the crack boundaries, i.e., the possibility of partially closed cracks, are considered. Unilateral crack identification has been studied. The numerical solution of the (ill-posed) inverse problem usually requires the use of specialized algorithms and techniques. Among others, we consider neural networks, filter-driven optimization and genetic algorithms. It seems that classical optimization works only in connection with sensitivity analysis for the accurate calculation of the first derivatives for classical cracks and for unilateral cracks). A short review of recent contributions in this area together with the numerical results of our on-going investigation will be presented in the conference. The effect of unilateral contact on the crack identification will be examined. Multiple-crack and multipleload identification problems will be considered. The effectiveness of various solution algorithms will be discussed. Promising directions of further research in this area will be pointed out. Refs. 7 (author)

  2. Structural Considerations on Fatigue Cracks

    Directory of Open Access Journals (Sweden)

    Cornel Bit

    2015-07-01

    Full Text Available This paper has been focused on the modern theoretical and experimental investigations on fatigue of metals which are now largely concentrated on three important areas: fatigue crack nucleation, short crack growth and long crack propagation. The main differences concerning the short cracks and long cracks mechanical investigation analysis have been presented.

  3. Structural Considerations on Fatigue Cracks

    OpenAIRE

    Cornel Bit

    2015-01-01

    This paper has been focused on the modern theoretical and experimental investigations on fatigue of metals which are now largely concentrated on three important areas: fatigue crack nucleation, short crack growth and long crack propagation. The main differences concerning the short cracks and long cracks mechanical investigation analysis have been presented.

  4. 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.

  5. BWR internal cracking issues

    International Nuclear Information System (INIS)

    The regulatory issues associated with cracking of boiling water reactor (BWR) internals is being addressed by the Nuclear Regulatory Commission (NRC) staff and is the subject of a voluntary industry initiative. The lessons learned from this effort will be applied to pressurized water reactor (PWR) internals cracking issues

  6. 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.

  7. Crack layer theory

    Science.gov (United States)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  8. Small-crack test methods

    Science.gov (United States)

    Larsen, James M.; Allison, John E.

    This book contains chapters on fracture mechanics parameters for small fatigue cracks, monitoring small-crack growth by the replication method, measurement of small cracks by photomicroscopy (experiments and analysis), and experimental mechanics of microcracks. Other topics discussed are the real-time measurement of small-crack-opening behavior using an interferometric strain/displacement gage; direct current electrical potential measurement of the growth of small cracks; an ultrasonic method for the measurement of the size and opening behavior of small fatigue cracks; and the simulation of short crack and other low closure loading conditions, utilizing constant K(max) Delta-K-decreasing fatigue crack growth procedures.

  9. Predicting crack arrest in reactor pressure vessels

    International Nuclear Information System (INIS)

    The pressurized thermal shock (PTS) issue has provided increased motivation for the search for a reasonably accurate crack arrest prediction methodology. This issue has assumed greater significance recently as a consequence of the imposition of Regulatory Guide 1.99 Revision 2 procedures for determining the effects of radiation embrittlement in the context of the screening criteria in the PTS rule that is used by the United States Nuclear Regulatory Commission to assess the integrity of reactor pressure vessels. The currently accepted procedure for predicting crack arrest is the so-called KIa procedure, which is based on static linear elastic fracture mechanics principles, with a crack being presumed to arrest when the crack tip stress intensity factor KIST falls below a value KIa. The present paper reviews recent EPRI sponsored research, which shows that the static procedure is overly conservative when it is applied to the first arrest of a deep crack in the thickness of a reactor vessel. This conclusion is clearly important when assessing the consequences of the imposition of the procedures of Regulatory Guide 1.99 Revision 2. A more accurate crack arrest prediction procedure, i.e. the Combustion Engineering constrained static procedure or the reflectionless stress intensity factor procedure which are very similar in concept and their arrest prediction, should be considered to assess the impact of its use in the context of the screening criteria limits in the PTS rule. (orig.)

  10. Biogasoline Production from Palm Oil Via Catalytic Hydrocracking over Gamma-Alumina Catalyst

    Directory of Open Access Journals (Sweden)

    Anondho Wijanarko

    2006-11-01

    Full Text Available Bio gasoline conversion from palm oil is an alternative energy resources method which can be substituted fossil fuel base energy utilization. Previous research resulted that palm oil can be converted into hydrocarbon by catalytic cracking reaction with γ-alumina catalyst. In this research, catalytic cracking reaction of palm oil by γ-alumina catalyst is done in a stirrer batch reactor with the oil/catalyst weight ratio variation of 100:1, 75:1, and 50:1; at suhue variation of 260 to 340oC and reaction time variation of 1 to 2 hour. Post cracking reaction, bio gasoline yield could be obtained after 2 steps batch distillation. Physical property test result such as density and viscosity of this cracking reaction product and commercial gasoline tended a closed similarity. According to result of the cracking product's density, viscosity and FTIR, it can conclude that optimum yield of the palm oil catalytic cracking reaction could be occurred when oil/catalyst weight ratio 100:1 at 340 oC in 1.5 hour and base on this bio gasoline's FTIR, GC and GC-MS identification results, its hydrocarbons content was resembled to the commercial gasoline. This palm oil catalytic cracking reaction shown 11.8% (v/v in yield and 28.0% (v/v in conversion concern to feed palm oil base and produced a 61.0 octane number's bio gasoline.

  11. Cracked fuel mechanics

    International Nuclear Information System (INIS)

    Fuel pellets undergo thermally induced cracking during normal reactor operation. Some fuel performance codes have included models that address the effects of fuel cracking on fuel rod thermal and mechanical behavior. However, models that rely too heavily on continuum mechanics formulations (annular gaps and solid cylindrical pellets) characteristically do not adequately predict cladding axial elongations. Calculations of bamboo ridging generally require many assumptions concerning fuel geometry, and some of the methods used are too complex and expensive to employ on a routine basis. Some of these difficulties originate from a lack of definition of suitable parameters which describe the cracked fuel medium. The methodology is being improved by models that describe cracked fuel behavior utilizing parameters with stronger physical foundations instead of classical continuum formulations. This paper presents a modelling concept and a set of measurable parameters that have been shown to improve the prediction of the mechanical behavior of cracked fuel/cladding systems without added computational expense. The transition from classical annular gap/cylindrical pellet models to modified bulk properties and further to local behavior for cracked fuel systems is discussed. The results of laboratory experiments to verify these modelling parameters are shown. Data are also presented from laboratory experiments on unirradiated and irradiated rods which show that fuel rod mechanical response depends on fuel fragment size. The impact of these data on cracked fuel behavior and failure modelling is also discussed. (author)

  12. 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.

  13. 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.

  14. Literature survey of cracking of alloy 600 penetrations in PWRs

    International Nuclear Information System (INIS)

    This report presents the results of a literature survey of cracking of alloy 600 components in PWR plants. Alloy 600 cracking of S/G tubes and/or plugs has been previously addressed. This report focuses on incidents occurring primarily in the pressurizer region. It documents these problems and recommends utility actions to address the issue of PWSCC of alloy 600 components in the primary system. Cracking problems have occurred both domestically and abroad. Information provided for each event includes plant, affected component, date of incident, plant date of commercial operation, detection method, outcome, remedial actions, and number of components cracked. Incidents are reported for US plants including San Onofre Nuclear Generating Station Unit 3, St. Lucie Unit 2, Arkansas Nuclear One Unit 2, and Calvert Cliffs Unit, and for Electricite de France. 38 refs., 21 figs., 3 tabs

  15. Crack motion in viscoelastic solids: the role of the flash temperature.

    Science.gov (United States)

    Carbone, G; Persson, B N J

    2005-07-01

    We present a simple theory of crack propagation in viscoelastic solids. We calculate the energy per unit area, G(v), to propagate a crack, as a function of the crack tip velocity v. Our study includes the non-uniform temperature distribution (flash temperature) in the vicinity of the crack tip, which has a profound influence on G(v). At very low crack tip velocities, the heat produced at the crack tip can diffuse away, resulting in very small temperature increase: in this "low-speed" regime the flash temperature effect is unimportant. However, because of the low heat conductivity of rubber-like materials, already at moderate crack tip velocities a very large temperature increase (of order of 1000 K) can occur close to the crack tip. We show that this will drastically affect the viscoelastic energy dissipation close to the crack tip, resulting in a "hot-crack" propagation regime. The transition between the low-speed regime and the hot-crack regime is very abrupt, which may result in unstable crack motion, e.g. stick-slip motion or catastrophic failure, as observed in some experiments. In addition, the high crack tip temperature may result in significant thermal decomposition within the heated region, resulting in a liquid-like region in the vicinity of the crack tip. This may explain the change in surface morphology (from rough to smooth surfaces) which is observed as the crack tip velocity is increased above the instability threshold. PMID:15997339

  16. 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

  17. The use of solid state nuclear magnetic resonance (NMR) to study the effect of composition on the properties of equilibrium fluid cracking catalysts (FCCs)

    Energy Technology Data Exchange (ETDEWEB)

    Occelli, M.L. [MLO Consulting, 6105 Black Water Trail, Atlanta, GA 30328-2716 (United States); Voigt, U.; Eckert, H. [Institut fur Physikalische Chemie Westfalische Wilhelms-Universitat Munster, Schlossplatz 7, D 48149 Munster (Germany)

    2004-03-15

    Solid state nuclear magnetic resonance (NMR) spectroscopy together with microactivity testing have been used to characterize the changes that occur in a fluid cracking catalyst (FCC) during gas oil cracking in a refinery fluid catalytic cracking unit (FCCU). The {sup 29}Si NMR spectra of fresh FCCs show the well known five peaks pattern attributed to the presence of HY-type crystals. However, after aging, equilibrium FCCs are generated in which the {sup 29}Si NMR spectrum of the zeolitic component is reduced to one main dominant resonance near -107ppm representative of T[4Si,0Al] sites. Thus, irrespective of composition, extensive dealumination of the cracking component in FCCs occurs during recirculation in a FCCU yielding {sup 29}Si NMR spectra in which the presence of framework Al is no longer visible. Similar conclusions have been obtained from the corresponding {sup 27}Al MAS NMR spectra showing that the dealuminated faujasite structure in equilibrium FCCs contains only extra-framework Al(IV), Al(V), and Al(VI) species. In the presence of tin, vanadium effects on the coordination of Al and Si in equilibrium FCCs, could not be observed by {sup 29}Si or {sup 27}Al NMR spectroscopy.

  18. Ethylene by Naphta Cracking

    Science.gov (United States)

    Wiseman, Peter

    1977-01-01

    Presents a discussion of the manufacture of ethylene by thermal cracking of hydrocarbon feedstocks that is useful for introducing the subject of industrial chemistry into a chemistry curriculum. (MLH)

  19. 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....

  20. 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

  1. CCRD application in the riser of a cold flow pilot unit with aid of gamma radiation transmission

    International Nuclear Information System (INIS)

    A central composite rotational design (CCRD) were performed in a vertical cylindrical reactor (riser) of a cold flow pilot unit (CFPU) of a Fluid Catalytic Cracking (FCC) unit, to obtain information about the fluid dynamics of gas-solid flow with aid of gamma radiation technique. The FCC of oil is Accomplished in the team with a short contact between the catalyst and the cracking of diesel fumes. The riser is part of a circulating fluidized bed (CFB) system. The factors adopted, or independent variables were the for the CCRD were the riser relative radial distance, air flow rate and mass flow rate of catalyst. The operating gas flow rate ranges from 166 L/min to 334 L/min, the relative radial distance from 0.020 to 0.044 (dimensionless) and mass flow rate of catalyst from 0.002kg/s to 0.022kg/s, the bed materials are all fluid catalytic cracking (FCC) particles with relatively small average diameter (72υ). Response variable was estimated with aid of gamma source (Am-241) and detector (NaI [Tl]) placed in diametrically opposite positions for information about the radial profile of volume fraction of the catalyst in the pilot unit riser, constructed in acrylic, with an internal diameter of 0.097m and height of 6.0 m. The results revealed that all factors are important, exerting a significant effect on the behavior of the catalyst volume fraction. (author)

  2. 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

  3. Crack growth and rupture characteristics of stress corrosion cracks

    International Nuclear Information System (INIS)

    The contribution describes rupture-mechanical studies on stress-corrosion cracks which occurred at components during use. The tests are complemented by test specimens with stress-corrosion cracks which were induced in the laboratory. The tests show that the stress-corrosion cracks of the tested higher-tensile heat-treatable steels have an intercrystalline crack development, crack branchings and multiple cracks with differing linear and depth expansions. With the same external stress and fracture toughness, the load on stress-corrosion cracks must be at least 1.4 times higher in order to initiate the fracture. The critical crack sizes are at least two times bigger than the result of a fracture-mechanical evaluation based on clean and unbranched cracks. (orig./RHM)

  4. 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.

  5. 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.

  6. The influence of extraframework aluminum on H-FAU catalyzed cracking of light alkanes

    OpenAIRE

    Narbeshuber, T.F.; Brait, A.; Seshan, K.; Lercher, J.A.

    1996-01-01

    The conversion of light linear and branched alkanes on two faujasite samples containing different concentrations of free Brønsted acid sites and extraframework alumina (EFAL) was studied between 733 K and 813 K. Protolytic cracking and bimolecular hydride transfer proceeded solely on Brønsted acid sites. For cracking of n-alkanes, the variation of the concentration of extraframework aluminum did not affect the catalytic activity per accessible Brønsted acid site. The activity to dehydrogenati...

  7. 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

  8. Crack propagation in Hastelloy X

    International Nuclear Information System (INIS)

    The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 6500C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air

  9. Crack-arrest technology

    International Nuclear Information System (INIS)

    Over the last several years, the Heavy Section Steel Technology (HSST) Program has conducted several fracture mechanics experiments on large specimens that produced crack-arrest fracture-toughness values above 220 MPa·√m, which is the limit imposed by the ASME Code and the limit included in the Issues on Pressurized Thermal Shock studies. It is therefore appropriate and timely to investigate the influence that these high crack-arrest data have on the integrity assessment of nuclear Reactor Pressure Vessels (RPVs). A review of the evolution of the Pressurized Thermal Shock (PTS) issue and current methods of analysis provides insight into the motivation for the HSST Program performing the large-specimen fracture mechanics experiments. During the early 1970s, it was recognized that RPVs could be subjected to severe thermal shock as the result of a large-break loss-of-coolant accident (LBLOCA). Analyses performed at that time indicated that thermal shock alone would not result in failure (through-wall cracking) of the vessel. However, a combination of pressure and a less severe thermal shock, the result of some postulated transients, could result in vessel failure. In March 1978, such a transient occurred at the Rancho Seco nuclear power plant. As a result of these events, parametric PTS studies were undertaken. Because of the apparent need for and the existence of high-temperature crack-arrest capability, the NRC HSST Program and others began to investigate the effect of higher crack-arrest values on the probability of failure and to determine if these values actually exist for prototypical RPV materials. This report describes the results of HSST Program large-specimen crack-arrest testing

  10. 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

    Present extended finite element method (XFEM) elements for cohesive crack growth may often not be able to model equal stresses on both sides of the discontinuity when acting as a crack-tip element. The authors have developed a new partly cracked XFEM element for cohesive crack growth with extra...... 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...... enrichments to the cracked elements. The extra enrichments are element side local and were developed by superposition of the standard nodal shape functions for the element and standard nodal shape functions for a sub-triangle of the cracked element. With the extra enrichments, the crack-tip element becomes...

  11. Diagnostics - Crack Detection '87

    International Nuclear Information System (INIS)

    The Proceedings of the International Symposium Diagnostics -Crack Detection '87 which was held from June 23 to 26 1987 in Sala (CSSR) contains 5 papers falling under the INIS Subject Scope. The said papers mainly deal with the problems of in-service diagnostics of pumps and steam turbines of nuclear power plants with WWER reactors, as well as crack detection of materials and welded joints of equipment and the control of the water regimen of the primary circuit of such power plants. (Z.M.)

  12. 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

  13. 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.

  14. Diffusion in fluid catalytic cracking catalysts on various displacement scales and its role in catalytic performance

    Czech Academy of Sciences Publication Activity Database

    Kortunov, P.; Vasenkov, S.; Kärger, J.; Fé Elía, M.; Perez, M.; Stöcker, M.; Papadopoulos, G. K.; Theodorou, D.; Drescher, B.; McElhiney, G.; Bernauer, B.; Krystl, V.; Kočiřík, Milan; Zikánová, Arlette; Jirglová, Hana; Berger, C.; Gläser, R.; Weitkamp, J.; Hansen, E. W.

    2005-01-01

    Roč. 17, č. 9 (2005), s. 2466-2474. ISSN 0897-4756 Grant ostatní: TROCAT project - European Community(DE) G5RD-CT-2001-00520 Institutional research plan: CEZ:AV0Z40400503 Keywords : FCC catalyst * adsorption * zeolite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.818, year: 2005

  15. 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.

  16. 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.)

  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 Cocaine and Infectious Tuberculosis

    OpenAIRE

    Story, A.; Bothamley, G.; Hayward, A.

    2008-01-01

    We hypothesize that crack cocaine is independently associated with smear-positive tuberculosis (TB). In a case-control study of TB in London, 19 (86%) of 22 crack cocaine users with pulmonary TB were smear positive compared with 302 (36%) of 833 non-drug users. Respiratory damage caused by crack cocaine may predispose drug users to infectivity.

  19. 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

  20. Modified Dugdale crack models - some easy crack relations

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    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 are......_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......) 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...

  1. Choked flow through cracks

    International Nuclear Information System (INIS)

    The leaks through steam-generator cracks are the subject of a research carried out in cooperation between EDF and UCL. A software called ECREVISSE to predict the mass flow rate has been developed and has been successfully validated. The purpose of the paper is to present the mathematical model used in ECREVISSE as well as some comparison between the results and the presently available data. The model takes into account the persistence of some metastable liquid in the crack and the special flow pattern which appears in such particular geometry. Although the model involves the use of several correlations (friction, heat transfer), no adjustment of parameters against the data has been needed, neither in the single-phase part of the flow, or in the two-phase part. (authors). 8 figs., 1 tab., 20 refs

  2. Delayed hydride cracking: alternative pre-cracking method

    International Nuclear Information System (INIS)

    The internal components of nuclear reactors built-in Zr alloys are prone to a failure mechanism known as Delayed Hydride Cracking (DHC). This situation has triggered numerous scientific studies in order to measure the crack propagation velocity and the threshold stress intensity factor associated to DHC. Tests are carried out on fatigued pre-crack samples to ensure similar test conditions and comparable results. Due to difficulties in implementing the fatigue pre-crack method it would be desirable to replace it with a pre-crack produced by the same process of DHC, for which is necessary to demonstrate equivalence of this two methods. In this work tests on samples extracted from two Zr-2.5 Nb tubes were conducted. Some of the samples were heat treated to obtain a range in their metallurgical properties as well as different DHC velocities. A comparison between velocities measured in test samples pre-cracked by fatigue and RDIH is done, demonstrating that the pre-cracking method does not affect the measured velocity value. In addition, the incubation (tinc), which is the time between the application of the load and the first signal of crack propagation, in samples pre-cracked by RDIH, was measured. It was found that these times are sufficiently short, even in the worst cases (lower speed) and similar to the ones of fatigued pre-cracked samples. (author)

  3. 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

  4. Crack interaction with microstructure

    Directory of Open Access Journals (Sweden)

    Sharvan Kumar

    2007-09-01

    Full Text Available Designing microstructure for damage tolerance requires a detailed understanding of how an advancing crack interacts with the microstructure (and sometimes modifies it locally at multiple length scales. Advances in experimental techniques, such as the availability of well-controlled straining stages for optical and electron microscopes, the focused ion beam, electron backscattered diffraction, and nanoindentation, enable probing at these length scales in real time and through interrupted tests. Simultaneously, increasing computational power coupled with new computational methods, such as finite element analysis (FEA incorporating cohesive elements at the continuum level, discrete dislocation methodology at the mesoscopic level, and coupled atomistic/continuum methods that transitions atomic level information to the mesoscopic level, have made it possible to begin addressing these complex problems. By reviewing crack growth in a variety of multiphase alloys including steels, titanium aluminides, Mo alloys, and nanocrystalline metals, we demonstrate various aspects of crack interaction with microstructure, and how these problems are being addressed through experiments and computations.

  5. Catalytic Synthesis Lactobionic Acid

    Directory of Open Access Journals (Sweden)

    V.G. Borodina

    2014-07-01

    Full Text Available Gold nanoparticles are obtained, characterized and deposited on the carrier. Conducted catalytic synthesis of lactobionic acid from lactose. Received lactobionic acid identify on the IR spectrum.

  6. 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.

  7. Catalytic Coanda combustion

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, J.D.; Smith, A.G.; Kopmels, M.

    1992-09-16

    A catalytic reaction is enhanced by the use of the Coanda effect to maximise contact between reactant and catalyst. A device utilising this principle comprises a Coanda surface which directs the flow of fuel from a slot to form a primary jet which entrains the surrounding ambient air and forms a combustible mixture for reaction on a catalytic surface. The Coanda surface may have an internal or external nozzle which may be axi-symmetric or two-dimensional. (author)

  8. Crack bridging in stress corrosion cracking of duplex stainless steels

    International Nuclear Information System (INIS)

    Wedge open loaded (WOL) specimens of age hardened Zeron 100 duplex stainless steel were tested in 3.5 wt % NaCl solution with cathodic polarizes applied at-900m V/SCE to investigate stress corrosion cracking mechanism in duplex stainless steel. The interaction between microstructure and mechanism of stress corrosion cracking was studied. Fracture mechanism was studied by using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The material was found cracked by ferrite cleavage, austenite tearing and austenite dissolution by environment. The ferrite cleavage took place along [100] planes and [112] twin habit planes. The austenite grains appear to act as crack bridging and crack arrester and failed by tearing and stress corrosion cracking. (author)

  9. CRACKS IN ROADWAY COVERING: METHODS FOR IMPROVEMENMT OF CRACK RESISTANCE

    Directory of Open Access Journals (Sweden)

    I. I. Leonovich

    2014-11-01

    Full Text Available Crack formation is presently considered as an actual problem in the global practice. The paper provides various approaches pertaining to improvement of asphalt-concrete composition with the purpose to prevent formation of temperature and fatigue cracks and develop design and technology measures for avoidance of reflection cracking in asphalt-concrete strengthening layers. However there is no comprehensive solution of the problem that combines a material science and affirmative approaches. Existing technology for crack sealing in roadway covering is rather efficient at the stage of its operation and makes it possible to eliminate cracks  depending on their nature and opening width but there is no efficient diagnostic and control system for preventing cracks with opening width up to1 mmwith the purpose to exclude their further development.

  10. 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.

  11. Asperities, Crack Front Waves and Crack Self Healing

    Science.gov (United States)

    Rajak, Pankaj; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya

    We have performed petascale simulations to study nanomaterial systems capable of sensing and repairing damage in high temperature/high pressure operating conditions. The system we have studied is a ceramic nanocomposite consisting of silicon carbide/silicon dioxide core/shell nanoparticles embedded in alumina. We observe that the interaction of the crack with core/shell asperities gives rise to crack-front waves. We also study crack healing by diffusion of silica into the crack as a function of nanoparticle size and inter-particle distance. Our results are well supported by experimental observations.

  12. On the Crack Bifurcation and Fanning of Crack Growth Data

    Science.gov (United States)

    Forman, Royce G.; Zanganeh, Mohammad

    2015-01-01

    Crack growth data obtained from ASTM load shedding method for different R values show some fanning especially for aluminum alloys. It is believed by the authors and it has been shown before that the observed fanning is due to the crack bifurcation occurs in the near threshold region which is a function of intrinsic properties of the alloy. Therefore, validity of the ASTM load shedding test procedure and results is confirmed. However, this position has been argued by some experimentalists who believe the fanning is an artifact of the test procedure and thus the obtained results are invalid. It has been shown that using a special test procedure such as using compressively pre-cracked specimens will eliminate the fanning effect. Since not using the fanned data fit can result in a significantly lower calculated cyclic life, design of a component, particularly for rotorcraft and propeller systems will considerably be impacted and therefore this study is of paramount importance. In this effort both test procedures i.e. ASTM load shedding and the proposed compressive pre-cracking have been used to study the fatigue crack growth behavior of compact tension specimens made of aluminum alloy 2524-T3. Fatigue crack growth paths have been closely observed using SEM machines to investigate the effects of compression pre-cracking on the crack bifurcation behavior. The results of this study will shed a light on resolving the existing argument by better understanding of near threshold fatigue crack growth behavior.

  13. New probabilistic fracture mechanics approach with neural network-based crack modeling: Its application to multiple cracks problem

    International Nuclear Information System (INIS)

    Studies on efficient utilization and life extension of operating nuclear power plants (NPPs) have become increasingly important since ages of the first-generation NPPs are approaching their design lives. In order to predict a remaining life of each plant, it is necessary to select those critical components that strongly influence the plant life, and to evaluate their remaining lives by considering aging effects of materials and other factors. This paper proposes a new method to incorporate sophisticated crack models, such as interaction and coalescence of multiple surface cracks, into probabilistic fracture mechanism (PFM) computer programs using neural networks. First, hundreds of finite element (FE) calculations of a plate containing multiple surface cracks are performed by parametrically changing crack parameters such as sizes and locations. A fully automated 3D FE analysis system is effectively utilized here. Second, the back-propagation neural network is trained using the FE solutions, i.e. crack parameters vs. their corresponding stress intensity factors (SIFs). After a sufficient number of training iterations, the network attains an ability to promptly output SIFs for arbitrary combinations of crack parameters. The well trained network is then incorporated into the parallel PFM program which runs on one of massively parallel computers composed of 512 processing units. To demonstrate its fundamental performances, the present computer program is applied to evaluate failure probabilities of aged reactor pressure vessels considering interaction and coalescence of two dissimilar semi-elliptical surface cracks

  14. Optimization of stochastic database cracking

    OpenAIRE

    Bhardwaj, Meenesh

    2013-01-01

    Variant Stochastic cracking is a significantly more resilient approach to adaptive indexing. It showed [1]that Stochastic cracking uses each query as a hint on how to reorganize data, but not blindly so; it gains resilience and avoids performance bottlenecks by deliberately applying certain arbitrary choices in its decision making. Therefore bring, adaptive indexing forward to a mature formulation that confers the workload-robustness that previous approaches lacked. Original cracking relies o...

  15. 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.

  16. Cracks in Fessenheim

    International Nuclear Information System (INIS)

    This document contains articles, expertises, comments on the problem of cracks as well as indications to other assumed lacks of safety in French and also German pressure water reactors. One chapter deals with the former Framatome safety engineer Etemad. Towards the end, there is also a chronological listing of regional events as well as articles from the supra-regional press. Now and then, selected remarks made by politicians are given which indicate an insufficient level of information in the responsible persons and which make clear that faults in the control instances can make existing reactor unsafeties even worse. (orig./HP)

  17. Stress corrosion cracking

    International Nuclear Information System (INIS)

    Comprehensive Structural Integrity is a reference work which covers all activities involved in the assurance of structural integrity. It provides engineers and scientists with an unparalleled depth of knowledge in the disciplines involved. The new online Volume 11 is dedicated to the mechanical characteristics of materials. This paper contains the chapter 11.03 and is structured as follows: General aspects of SCC testing; Non-precracked specimens; Precracked specimens - the fracture mechanics approach to SCC; Crack growth measurement; Limitations of the LEFM approach to SCC; The use of SCC data; Guide to selection of mechanical scc test method

  18. 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...

  19. Some practical crack path examples

    Directory of Open Access Journals (Sweden)

    Les P. Pook

    2007-07-01

    Full Text Available It is well known that many engineering structures and components, as well as consumer items, contain cracks or crack-like flaws. It is widely recognised that crack growth must be considered both in designand in the analysis of failures. The complete solution of a crack growth problem includes determination of the crack path. Macroscopic aspects of crack paths have been of industrial interest for a very long time.At the present state of the art the factors controlling the path taken by a crack are not completely understood.Eight brief case studies are presented. These are taken from the author’s professional and personal experience of macroscopic crack paths over many years. They have been chosen to illustrate various aspects of crack paths. One example is in a component from a major structure, three examples are in laboratory specimens, and four are in nuisance failures. Such nuisance failures cause, in total, a great deal of inconvenience and expensive, but do not normally receive much publicity.

  20. Periodic cracks of an elastic semi-infinite plate under thermal shock

    International Nuclear Information System (INIS)

    Full text: The thermal shock problems of cracked elastic bodies arise in many practical applications such as aircrafts, gas turbine engines, nuclear plants, pressure vessels, etc. Most of the studies are related to single cracked elastic strip under thermal shock conditions. Few studies of multiple cracks under thermal loading are considered. In this work the problem of periodic cracks perpendicular to the boundary of a semi-infinite plate under transient thermal stresses is considered. A unit step function and a ramp function temperature change at the boundary of the plate are used to create the thermal shock. Although the unit step function will give a conservative results, the ramp function will be a realistic representation of the temperature at the boundary. The problem is solved by using superposition technique. The thermal stresses that are obtained from uncracked problem are used with opposite sign as a crack surface traction to formulate the perturbation problem. The solution of the perturbation problem is obtained by expressing the displacement components in terms of sums of finite and infinite Fourier transforms resulting in a singular integral equation of Cauchy-type that is solved numerically. The primary calculated quantity is the stress intensity factor for edge cracks and integral cracks. For both cases, the effect of time, the crack length, the location of the crack and the periodic spacing between cracks are presented. Refs. 7 (author)

  1. 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.

  2. A study on fatigue crack propagation considering crack tip plasticity

    International Nuclear Information System (INIS)

    Fatigue crack propagation of materials considering crack tip plasticity was studied. For this, fatigue tests were performed with compact tension (CT) specimens of Inconel 690, Inconel 600, Inconel 718 and Type 304 stainless steel at room temperature. Fatigue test on Inconel 600 was performed to be used as a reference data of Inconel 690. Inconel 718 specimen, which has very high yield strength, was selected to simulate different plasticity at the crack tip in comparison with 304 stainless steel. The effect of specimen thickness on fatigue crack propagation was studied with 304 stainless steel of 3mm-, 6mm- and 25mm-thick specimens. Inconel 690 has been proposed as a substitute material for Inconel 600 in pressurized water reactor (PWR) steam generator tube application. This alloy was developed to improve the stress corrosion cracking resistance of Inconel 600. Now, it is known that Inconel 690 has better intergranular stress corrosion cracking (IGSCC) property than Inconel 600. But, more data of Inconel 690 about mechanical properties are needed in steam generator design. To investigate the effects of heat treatment on yield strength and fatigue crack propagation of Inconel 690, tensile tests and fatigue tests were performed on heat-treated specimen. From the test results, it is believed that chromium carbide precipitates at the grain boundaries reduce fatigue crack growth rate (FCGR) of Inconel 690 by crack tip blunting as far as the fatigue cracking is intergranular fracture mode. To investigate the effect of residual stress on fatigue crack propagation, residual stresses were introduced by induction-heat treatment. And, the distribution of residual stresses was measured with 3mm-thick 304 stainless steel by X-ray diffraction (XRD) measurement. From the tests, it was found that FCGR was increased in tensile residual stress region and decreased in compressive region. From the fatigue tests on 304 stainless steel, it was found that FCGR of thick specimen was faster

  3. Effect of Crack Opening on Penetrant Crack Detectability

    Science.gov (United States)

    Weaver, Devin

    2009-01-01

    Results: From the testing we were able to determine all the cracks within the test range were detectable or better with developer. Many of the indications after development lost their linearity and gave circular indications. Our tests were performed in a laboratory and our procedure would be difficult in an industrial setting. Conclusions: The "V" did not significantly affect our ability to detect the POD cracks with fluorescent penetrant. Conduct same experiment with more cracks. The 0.025 and 0.050 POD specimens are clean and documented with the SEM. Conduct water-wash fluorescent penetrant test at EAFB. The poppet cracks are tighter than the POD specimen cracks. Flight FCV poppets: 0.01 mils (0.3 microns) Langley fatigue cracked poppets: 0.02 mils (0.5 microns) POD specimen (post 5 mils): 0.05 mils (1.4 microns) We could not detect cracks in Langley fatigue-cracked poppets with fluorescent penetrant. Investigate inability of penetrant to wet the poppet surface.

  4. 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

  5. Replica-Based Crack Inspection

    Science.gov (United States)

    Newman, John A.; Willard, Scott A.; Smith, Stephen W.; Piascik, Robert S.

    2008-01-01

    Surface replication has been proposed as a method for crack detection in space shuttle main engine flowliner slots. The results of a feasibility study show that examination of surface replicas with a scanning electron microscope can result in the detection of cracks as small as 0.005 inch, and surface flaws as small as 0.001 inch, for the flowliner material.

  6. Interface cracks in piezoelectric materials

    Science.gov (United States)

    Govorukha, V.; Kamlah, M.; Loboda, V.; Lapusta, Y.

    2016-02-01

    Due to their intrinsic electromechanical coupling behavior, piezoelectric materials are widely used in sensors, actuators and other modern technologies. It is well known that piezoelectric ceramics are very brittle and susceptible to fracture. In many cases, fracture occurs at interfaces as debonding and cracks. This leads to an undesired degradation of electrical and mechanical performance. Because of the practical and fundamental importance of the problem, interface cracks in piezoelectric materials have been actively studied in the last few decades. This review provides a comprehensive survey of recent works on cracks situated at the interface of two materials, at least one of which has piezoelectric or piezoelectromagnetic properties. Different electric boundary conditions along the crack faces are discussed. The oscillating and contact zone models for in-plane straight interface cracks between two dissimilar piezoelectric materials or between piezoelectric and non-piezoelectric ones are reviewed. Different peculiarities related to the investigation of interface cracks in piezoelectric materials for the anti-plane case, for functionally graded and thermopiezoelectric materials are presented. Papers related to magnetoelectroelastic bimaterials, to steady state motion of interface cracks in piezoelectric bimaterials and to circular arc-cracks at the interface of piezoelectric materials are reviewed, and various methods used to address these problems are discussed. The review concludes with an outlook on future research directions.

  7. 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).

  8. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  9. 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.

  10. Monolithic catalytic igniters

    Science.gov (United States)

    La Ferla, R.; Tuffias, R. H.; Jang, Q.

    1993-01-01

    Catalytic igniters offer the potential for excellent reliability and simplicity for use with the diergolic bipropellant oxygen/hydrogen as well as with the monopropellant hydrazine. State-of-the-art catalyst beds - noble metal/granular pellet carriers - currently used in hydrazine engines are limited by carrier stability, which limits the hot-fire temperature, and by poor thermal response due to the large thermal mass. Moreover, questions remain with regard to longevity and reliability of these catalysts. In this work, Ultramet investigated the feasibility of fabricating monolithic catalyst beds that overcome the limitations of current catalytic igniters via a combination of chemical vapor deposition (CVD) iridium coatings and chemical vapor infiltration (CVI) refractory ceramic foams. It was found that under all flow conditions and O2:H2 mass ratios tested, a high surface area monolithic bed outperformed a Shell 405 bed. Additionally, it was found that monolithic catalytic igniters, specifically porous ceramic foams fabricated by CVD/CVI processing, can be fabricated whose catalytic performance is better than Shell 405 and with significantly lower flow restriction, from materials that can operate at 2000 C or higher.

  11. Stress corrosion cracking of steam generator components from 08X18H10T steel

    International Nuclear Information System (INIS)

    Several analyses (metallographic and electron fractographic studies, Auger electron spectroscopy of corrosion deposits, film chemical composition on fracture surfaces by SIMS, X-ray analysis...) of a cracked steam generator collector flange made of 08X18H10T steel of a PWR-440 unit, have been carried out in order to explain the stress corrosion cracking of the metal. Among other conclusions, it is shown that the trans-crystalline corrosion cracking of the steel appears to be an alkaline one under the local non-passivating effect of chloride ions and the adsorption of hydrogen by a metal at a crack tip. 8 refs., 12 figs., 2 tabs

  12. Production of hydrogen by thermocatalytic cracking of natural gas. Task 4 report; Annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-01

    The conventional methods of hydrogen production from natural gas, for example, steam reforming (SR), are complex multi-step processes. These processes also result in the emission of large quantities of CO{sub 2} into the atmosphere. One alternative is the single-step thermocatalytic cracking (TCC) (or decomposition) of natural gas into hydrogen and carbon. The comparative assessment of SR and TCC processes was conducted. Thermocatalytic cracking of methane over various catalysts and supports in a wide range of temperatures (500--900 C) and flow rates was conducted. Two types of fix bed catalytic reactors were designed, built and tested: continuous flow and pulse reactors. Ni-Mo/Alumina and Fe-catalysts demonstrated relatively high efficiency in the methane cracking reaction at the range of temperatures 600--800 C. Fe-catalyst demonstrated fairly good stability, whereas alumina-supported Pt-catalyst rapidly lost its catalytic activity. Methane decomposition reaction over Ni-Mo/alumina was studied over wide range of space velocities in a continuous flow fixed bed catalytic reactor. The experimental results indicate that the hydrogen yield decreases noticeably with an increase in the space velocity of methane. The pulse type catalytic reactor was used to test the activity of the catalysts. It was found that induction period on the kinetic curve of hydrogen production corresponded to the reduction of metal oxide to metallic form of the catalyst. SEM method was used to study the structure of the carbon deposited on the catalyst surface.

  13. The Cracking of Irradiated Uranium

    International Nuclear Information System (INIS)

    Structural features other than fission-product gas bubbles seen in unrestrained, unalloyed uranium irradiated in the alpha range to burn-ups of up to 0.7% of all atoms are described. The main features are: (1) Brittle grain-boundary cracks in which the grains appear to have parted without plastic deformation. These cracks are associated with thermal cycling and high maximum temperatures (~600°C). (2) Transgranular cracks, which are comparatively rare. It is suggested that they may be related to the pseudo-cleavage or ''twin parting'' observed in unirradiated uranium by Cahn. (3) Grain boundary ''creep voids'' believed to arise from the coalescence of vacancies under tensile stress. The voids may form a path for crack propagation or may themselves coalesce to form cracks. Apart from the direct effects of these features in increasing the volume and changing the thermal conductivity and mechanical properties of the uranium, a mechanism is discussed by which cracks may accumulate fission-product gas and cause further volume increases. The possible effects of structural variations in the uranium and of restraint during irradiation on the incidence of cracking and void formation are considered. (author)

  14. Relation Between Acid and Catalytic Properties of Chlorinated Gamma-Alumina. a 31p Mas Nmr and Ftir Investigation

    Directory of Open Access Journals (Sweden)

    Guillaume D.

    1999-07-01

    Full Text Available In this paper, we have studied the effect of chlorine on the surface properties of gamma-alumina, especially on their acid properties. The use of FTIR spectroscopy and 31P MAS NMR of adsorbed trimethylphosphine allows to propose a chlorination mechanism. To correlate the surface properties of these chlorinated gamma-alumina with their catalytic properties, we have used a model reaction, the cracking of n-heptane under reforming conditions. The analysis of the correlation between acid properties determined by 31P MAS NMR and the catalytic results (in terms of activities and selectivities allows to identify which sites are involved in the cracking reaction.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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 inten...... value problem, and a displacement boundary value problem. The results show that the stress intensity factors and the displacement intensity factors do not depend explicitly upon the velocity of the crack tip.......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...... intensity factors. In the special case of a constant Poisson ratio only 2 deformation intensity factors are needed. Closed form solutions are given both for a slowly growing crack and for a crack that is suddenly arrested at a point at the crack extension path. Two examples are studied; a stress boundary...

  20. 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.

  1. Caustic stress corrosion cracking

    International Nuclear Information System (INIS)

    Liquid Metal Fast Breeder Reactors (LMFBRs) use sodium as a coolant for transfer of heat from the core to the steam generators. Maintenance and examination of the system require removal of sodium from components of the system. One process for removal reacts the sodium with water vapor and removes the residual sodium hydroxide from the components by rinsing with liquid water. This process exposes components such as pumps, heat exchangers, valves, and fuel-handling machines to contact with aqueous NaOH solutions in various concentrations over a range of temperatures and times. Since stress can be present in these components, as generated by fabrication, structural loads, deformation in service, and possible wedging action by corrosion products, conditions are potentially available for the mechanism of caustic stress corrosion cracking (CSCC). Since LMFBR components are fabricated from Types 304 and 316 stainless steels which have been found to be susceptible to CSCC, it was therefore considered necessary to establish the threshold of CSCC so that the components could be processed under conditions avoiding CSCC. The materials used in the testing program included heats of Types 304 and 316 stainless steel, Inconel 600 and 718, hardfacing deposits of Stellite 6 and 156, and three special wear-resistant, carbide-type materials. The analysis of these materials is tabulated

  2. Super oil cracking update

    International Nuclear Information System (INIS)

    The conversion of residual fuel oil to usable middle distillates was discussed. The residue conversion processing paths are usually based on separation, carbon rejection, or hydrogen addition principles. Super Oil Cracking (SOC) uses a slurry catalyst system in a new, tubular reactor to achieve high levels of hydrothermal conversion. SOC can upgrade a variety of heavy, high metals residue feedstocks with high yields of middle distillates. The SOC products can also be further treated into feedstocks for FCC or hydrocracking. The SOC process can be incorporated easily into a refinery to obtain incremental residue conversion directly. It can also be integrated with other residue processes, acting as a demetallization and decarbonization step which results in enhanced overall conversion. The relative rate of coke formation and its handling are distinguishing characteristics between residue upgrading technologies. The SOC process operates at higher temperatures that other residue hydrocracking processes resulting in higher rates of thermal decomposition, thus preventing coke formation. SOC process can operate as a stand-alone upgrader or can be integrated with other bottoms processing steps to extend the refiner's range of options for increasing bottoms conversion.3 tabs., 14 figs

  3. Dual component cracking catalyst with vanadium passivation and improved sulfur tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, J.V.; Jossens, L.W.

    1991-01-29

    This patent describes a dual component catalyst composition for the catalytic cracking of metal-containing hydrocarbonaceous feedstock. It comprises: a first component comprising an active cracking catalyst; and a second component, as a separate and distinct entity. The second component comprises: a calcium and magnesium containing material selected from the group consisting of dolomite, substantially amorphous calcium magnesium silicate, calcium magnesium oxide, calcium magnesium acetate, calcium magnesium carbonate, and calcium magnesium subcarbonate; a magnesium containing material comprising a hydrous magnesium silicate, and a binder selected from the group consisting of kaolin, bentonite, montmorillonite, saponite, hectorite, alumina, silica, titania, zirconia, silica-alumina, and combinations thereof.

  4. 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.

  5. 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...

  6. 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.)

  7. Kinking conditions for running cracks

    OpenAIRE

    Andrianopoulos, N.; Kourkoulis, S.

    1994-01-01

    The problem of the abrupt change of the direction of a crack, propagating with high velocity, is studied in the present work. The study is based on a unified approach of the directional instability phenomena, which accompany running cracks. According to this approach, the running tip is simulated by a prebranched configuration, consisted of two microcracks of arbitrary lengths and orientations. The final macroscopically observed result depends both on these, a priori unknown, relative lengths...

  8. BWR pipe crack remedies evaluation

    International Nuclear Information System (INIS)

    This paper presents results on: (a) the influence of simulated BWR environments on the stress-corrosion-cracking (SCC) susceptibility of types 304, 316 NG, and 347 stainless steel (SS), (b) fracture-mechanics crack growth rate measurements on these materials and weld overlay specimens in different environments, and (c) residual stress measurements and metallographic evaluations of conventional pipe weldments treated by a mechanical-stress-improvement process (MSIP) as well as those produced by a narrow-gap welding procedure. Crack initiation studies on types 304 and 316 NG SS under crevice and non-crevice conditions in 2890C water containing 0.25 ppm dissolved oxygen with low sulfate concentrations indicate that SCC initiates at low strains (3%) in the nuclear grade material. Crack growth measurements on fracture-mechanics-type specimens, under low-frequency cyclic loading, show that the type 316 NG steel cracks at a somewhat lower rate (≅ 40%) than sensitized type 304 SS in an impurity environment with 0.25 ppm dissolved oxygen; however, the latter material stops cracking when sulfate is removed from the water. Crack growth in both materials ceases under simulated hydrogen-water chemistry conditions (6 ppb oxygen) even with 100 ppb sulfate present in the water. An unexpected results was obtained in the test on a weld overlay specimen in the impurity environment, viz., the crack grew to the overlay interface at a nominal rate, branched at 900 in both directions, and then grew at a high rate (parallel to the nominal applied load). Residual stress measurements on MSIP-treated weldments and those produced by a narrow-gap welding procedure indicate that these techniques produce compressive stresses over most of the inner surface near the weld and heat-affected zones. (orig.)

  9. 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.

  10. Wide plate crack arrest testing

    International Nuclear Information System (INIS)

    To predict the behavior of a nuclear pressure vessel undergoing pressurized thermal shock, certain information on dynamic crack propagation and arrest is required. The purpose of the work described is to provide such data on wide plates fracturing at temperatures up to the upper shelf region. Four tests have been completed on the 26 MN Universal Testing Machine at NBS. The specimens are to be fractured in a thermal gradient that, in the most extreme case, might extend from -1000C to 2000 across the 1 meter specimen width. This is done so that the crack will initiate in a cold, brittle region and arrest in a hot, tough region. An important part of this study is data acquisition from the numerous strain gages, thermocouples, timing wires, crack mouth opening displacement gages, and acoustic emission transducers that are mounted on the specimen. Each test has been different with respect to conditions of testing, specimen configuration, and instrumentation used. The progressive changes in test procedure represent attempts to obtain the desired crack run and arrest behavior and to improve upon the quality of the data collected. In particular, efforts were made to initiate crack propagation at lower stress intensity factors. Also, strain gage combinations and locations were optimized to better deduce the crack position as a function of time. Another result of great interest that can be deduced from these tests is the initiation of fracture toughness and the arrest toughness

  11. Mitigation of Crack Damage in Metallic Materials

    Science.gov (United States)

    Leser, Patrick E.; Newman, John A.; Smith, Stephen W.; Leser, William P.; Wincheski, Russell A.; Wallace, Terryl A.; Glaessgen, Edward H.; Piascik, Robert S.

    2014-01-01

    A system designed to mitigate or heal crack damage in metallic materials has been developed where the protected material or component is coated with a low-melting temperature film. After a crack is formed, the material is heated, melting the film which then infiltrates the crack opening through capillary action. Upon solidification, the healing material inhibits further crack damage in two ways. While the crack healing material is intact, it acts like an adhesive that bonds or bridges the crack faces together. After fatigue loading damages, the healing material in the crack mouth inhibits further crack growth by creating artificially-high crack closure levels. Mechanical test data show that this method sucessfully arrests or retards crack growth in laboratory specimens.

  12. Salinity effects on the dynamics and patterns of desiccation cracks

    Science.gov (United States)

    Shokri, N.; Zhou, P.

    2012-12-01

    Cracking arising from desiccation is a ubiquitous phenomenon encountered in various industrial and geo-environmental applications including drying of clayey soil, cement, ceramics, gels, and many more colloidal suspensions. Presence of cracks in muddy sediments modifies the characteristics of the medium such as pore structure, porosity, and permeability which in turn influence various flow and transport processes. Thus it remains a topic of great interest in many disciplines to describe the dynamics of desiccation cracking under various boundary conditions. To this end, we conducted a comprehensive study to investigate effects of NaCl concentrations on cracking dynamics and patterns during desiccation of Bentonite. Mixtures of Bentonite and NaCl solutions were prepared with NaCl concentration varying from 2 to 10 percent in 0.5 percent increment (totally 17 configurations). The slurry was placed in a Petri dish mounted on a digital balance to record the evaporation dynamics. The atmospheric conditions were kept constant using an environmental chamber. An automatic camera was used to record the dynamics of macro-cracks (mm scale) at the surface of desiccating clay each minute. The obtained results illustrate the significant effects of salt concentration on the initiation, propagation, morphology and general dynamics of macro-cracks. We found that higher salt concentrations results in larger macro cracks' lengths attributed to the effects of NaCl on compressing the electric double layer of particles at increasing electrolyte concentrations which reduce considerably the repulsive forces among the particles and causing instability of the slurry and flocculation of the colloidal particles. Rheological measurements by means of a stress controlled rheometer revealed that the yield stress of the slurry decreases as NaCl concentration increases which may indicate aggregation of larger units in the slurry as a result of flocculation causing larger cracks' lengths due to

  13. Observation of Intralaminar Cracking in the Edge Crack Torsion Specimen

    Science.gov (United States)

    Czabaj, Michael W.; Ratcliffe, James G.; Davidson, Barry D.

    2013-01-01

    The edge crack torsion (ECT) test is evaluated to determine its suitability for measuring fracture toughness associated with mode III delamination growth onset. A series of ECT specimens with preimplanted inserts with different lengths is tested and examined using nondestructive and destructive techniques. Ultrasonic inspection of all tested specimens reveals that delamination growth occurs at one interface ply beneath the intended midplane interface. Sectioning and optical microscopy suggest that the observed delamination growth results from coalescence of angled intralaminar matrix cracks that form and extend across the midplane plies. The relative orientation of these cracks is approximately 45 deg with respect to the midplane, suggesting their formation is caused by resolved principal tensile stresses arising due to the global mode-III shear loading. Examination of ECT specimens tested to loads below the level corresponding to delamination growth onset reveals that initiation of intralaminar cracking approximately coincides with the onset of nonlinearity in the specimen's force-displacement response. The existence of intralaminar cracking prior to delamination growth onset and the resulting delamination extension at an unintended interface render the ECT test, in its current form, unsuitable for characterization of mode III delamination growth onset. The broader implications of the mechanisms observed in this study are also discussed with respect to the current understanding of shear-driven delamination in tape-laminate composites.

  14. Crack growth and fracture behaviour of stress corrosion cracks of turbine generator steels

    International Nuclear Information System (INIS)

    The object of this investigation was the quantifying of the behaviour of cracks which were induced during service under corrosive media. To investigate the influence of stress corrosion crack configurations on stress intensity factor, six different test materials from 2 and 3.5% NiCrMoV and 2% Cr/1% Ni steels were chosen. The stress corrosion cracks were induced at wedge loaded compact tension specimens in a corrosive media in the laboratory. Fracture mechanics tests as well as fatigue crack growth tests were performed at these specimens. All stress corrosion cracks have an intercrystalline path and a crack length longer than 1 mm; they are multiple and have branched cracks tips. The fracture mechanics tests at these stress corrosion cracks induced in the laboratory and during service of components show that their stress intensity factor is 30 to 70% smaller than the stress intensity factor calculated for single straight cracks too. Theoretical calculations arrived to the same results. Crack initiation and growth behaviour under cyclic loading starting from these stress corrosion cracks results in that the load or the stress intensity range ΔK has to be increased three times larger than the ΔK-threshold value to induce crack initiation. The crack growth velocity influenced by multiple crack tips and multiple growing cracks from these crack tips is much lower than the crack growth velocity of a normal fatigue crack (one crack tip). (orig./MM) With 32 figs

  15. 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

  16. 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

  17. 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.

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

    International Nuclear Information System (INIS)

    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

  19. Off-center crack growth analysis of inner-surface crack pipe

    International Nuclear Information System (INIS)

    Background: There is a discrepancy between off-center crack and center-crack. Purpose: Crack grow rule and path need to be investigated under different load conditions. Methods: 3D elastic finite element method is used to create an off-center inner-surface crack model based on Paris-law crack grow equation by ABAQUS. Results: Crack grow rule and path are obtained under different load conditions, The influence of the crack rotation angle to crack extension has been researched. At the same time, centered circumferential crack model has been compared with off-centered circumferential crack model, and the discrepancy has been found. Conclusions: In LBB analysis, off-center influence should be considered in crack leakage analysis, but not necessary in crack stability analysis. (author)

  20. 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)

  1. Catalytic reforming process

    Energy Technology Data Exchange (ETDEWEB)

    Absil, R.P.; Huss, A. Jr.; McHale, W.D.; Partridge, R.D.

    1989-06-13

    This patent describes a catalytic reforming process which comprises contacting a naphtha range feed with a low acidity extrudate comprising an intermediate and/or a large pore acidic zeolite bound with a low acidity refractory oxide under reforming conditions to provide a reaction product of increased aromatic content, the extrudate having been prepared with at least an extrusion-facilitating amount of a low acidity refractory oxide in colloidal form and containing at least one metal species selected from the platinum group metals.

  2. 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...

  3. 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

  4. 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 ...

  5. 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.

  6. Addressing concrete cracking in NPPs

    International Nuclear Information System (INIS)

    The phenomenon of concrete cracking is one of the most frequently encountered deterioration at NPPs as it has been shown by a wide Survey of NPPs performed by IAEA in 1994-95 It can be due to a multitude of causes such as the normal ageing process (shrinkage, creep, prestressing force loss) as well as exposure to the environment (temperature variation, moisture, freeze/thaw, etc) The above mentioned Survey has also shown that in 64% of cases, no action was taken or required. It became also obvious that there is a lack of guidance as when remedial actions are needed. The paper describes, with the help of a Flow Chart, the various stages to be considered, from the first step of identification of cracks, to the definition of causes, evaluation of extent of damage, evaluation of effect/implications (safety, reliability), to the final step of deciding if repair action is required. Finally, based upon a wide literature survey the paper proposes in a Chart format, Criteria for addressing concrete cracks in NPPs., when taking in considerations all these factors. This paper discusses the process which should lead to the selection of an effective repair method and proposes, based upon worldwide standards and literature, criteria which should lead to the decision whether to repair or not concrete cracks, after the cracks have been identified and evaluated, addressing the entire range of aspects involved. (author)

  7. Paths of interactive cracks in creep conditions

    Directory of Open Access Journals (Sweden)

    K. Nowak

    2015-10-01

    Full Text Available The paper contains plane strain analysis of uniformly stretched plate working in creep condition. The plate contains initial defects in forms of central and/or edge cracks working in mode I. These cracks are modelled by attributing critical value of damage parameter to preset points and therefore resulting in stresses set to zero (material does not support any loading. The Continuum Damage Mechanics constitutive equations are used to describe the creep crack growth problem and Finite Element Method Abaqus system is applied to solve corresponding boundary and initial value problem. Analysis of different initial cracks configuration has been performed. The crack path is defined by points in which damage parameter equals to critical one. Time to failure of the plate with single initial crack is achieved when the crack path spans its width. This time is calculated and compared to the time to failure of initially uncracked structure. For the plate with multiple cracks the paths starting from different cracks can develop independently until they merge and/or span the plate width. In each case the damage field is analysed and the direction of crack path development is determined. The analysis of crack propagation allows for determination of a distance between initial cracks for which the interaction between them is negligible. It is demonstrated that Continuum Damage Mechanics approach allows not only to model the development of initially existing cracks but also initiation of new, cross-spanning cracks and their kinking and branching.

  8. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

    OpenAIRE

    Hebé Gurdián; Eva García-Alcocel; Francisco Baeza-Brotons; Pedro Garcés; Emilio Zornoza

    2014-01-01

    The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of ...

  9. 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.

  10. 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.

  11. 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.

  12. Dynamic experiments on cracked pipes

    International Nuclear Information System (INIS)

    In order to apply the leak before break concept to piping systems, the behavior of cracked pipes under dynamic, and especially seismic loading must be studied. In a first phase, an experimental program on cracked stainless steel pipes under quasi-static monotonic loading has been conducted. In this paper, the dynamic tests on the same pipe geometry are described. These tests have been performed on a shaking table with a mono frequency input signal. The main parameter of the tests is the frequency of excitation versus the frequency of the system

  13. 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.

  14. 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)

  15. 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.)

  16. Reducing NOx emissions from FCC regenerators by segregated cracking of feed

    International Nuclear Information System (INIS)

    This patent describes improvement in a fluidized catalytic cracking process wherein a fresh feed mixture of high and low nitrogen containing hydrocarbon feeds contact a source of hot regenerated catalyst in the base of a riser cracking reactor means to produce catalytically cracked products and spent catalyst containing coke contaminated with nitrogen compounds, wherein the spent catalyst is stripped in a catalyst stripping means to produce stripped catalyst which is regenerated in a catalyst regeneration means to produce a regenerated catalyst which is recycled to the cracking reactor means, and wherein a flue gas comprising nitrogen oxides (NOx) is withdrawn from the regenerator. The improvement comprises: segregating the fresh feed mixture into at least two different fresh feed fractions having different nitrogen contents, the segregated feed fractions comprising a low nitrogen content fresh feed and a high nitrogen content fresh feed having at least a 50% greater concentration of nitrogen than the low nitrogen content fresh feed, adding the high nitrogen content fresh feed via a feed addition means at an elevation in the base of the riser reactor, and separately adding the low nitrogen content fresh feed to the riser reactor at a higher elevation in the riser reactor and downstream of the point of addition of the high nitrogen content fresh feed, whereby the NOx content of the flue gas is reduced relative to operation with a feed comprising a mixture of the high and the low nitrogen containing feedstocks

  17. Evolution of random catalytic networks

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, S.M. [Santa Fe Inst., NM (United States); Reidys, C.M. [Santa Fe Inst., NM (United States)]|[Los Alamos National Lab., NM (United States)

    1997-06-01

    In this paper the authors investigate the evolution of populations of sequences on a random catalytic network. Sequences are mapped into structures, between which are catalytic interactions that determine their instantaneous fitness. The catalytic network is constructed as a random directed graph. They prove that at certain parameter values, the probability of some relevant subgraphs of this graph, for example cycles without outgoing edges, is maximized. Populations evolving under point mutations realize a comparatively small induced subgraph of the complete catalytic network. They present results which show that populations reliably discover and persist on directed cycles in the catalytic graph, though these may be lost because of stochastic effects, and study the effect of population size on this behavior.

  18. 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.

  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. Crack Formation in Cement-Based Composites

    Science.gov (United States)

    Sprince, A.; Pakrastinsh, L.; Vatin, N.

    2016-04-01

    The cracking properties in cement-based composites widely influences mechanical behavior of construction structures. The challenge of present investigation is to evaluate the crack propagation near the crack tip. During experiments the tension strength and crack mouth opening displacement of several types of concrete compositions was determined. For each composition the Compact Tension (CT) specimens were prepared with dimensions 150×150×12 mm. Specimens were subjected to a tensile load. Deformations and crack mouth opening displacement were measured with extensometers. Cracks initiation and propagation were analyzed using a digital image analysis technique. The formation and propagation of the tensile cracks was traced on the surface of the specimens using a high resolution digital camera with 60 mm focal length. Images were captured during testing with a time interval of one second. The obtained experimental curve shows the stages of crack development.

  1. Influence of de-aluminating techniques of Y zeolite on its physico-chemical properties and on its catalytic performances in N-decane hydro-cracking; Influence des techniques de desalumination de la zeolithe Y sur ses proprietes physico-chimiques et sur ses performances catalytiques en hydrocraquage du N-decane

    Energy Technology Data Exchange (ETDEWEB)

    Gola, A.

    1996-12-16

    De-aluminated HY samples with constant amounts of framework aluminium and varying amounts of extra framework aluminium have been prepared and characterized. The influence of extra framework aluminium (EFAL) species in hydrocracking of n-decane at a hydrogen pressure of 60 bars has been evaluated. The methods used to de-aluminate the Y zeolite involved high temperature steaming followed by treatments with aqueous solutions of nitric acid, (NH{sub 4}){sub 2}SIF{sub 6}(AHFS) or Na{sub 2}EDTA to control the elimination of the EFAI. The chemical composition of the resulting samples indicates that only AHFS and Na{sub 2}EDTA are able to eliminate controlled amounts of EFAI without de-aluminating the framework. Several types of EFAI are detected, their localisation is proposed and their ease of extraction by the different reagents is investigated. Treatment with nitric acid or Na{sub 2}EDTA leads to increase of the meso-porous volume whereas AHFS leads to a silicon deposit and very low meso-porous volumes. The number and strength of acid sites in all treated samples is higher than in the steamed zeolite. Hydrocracking of n-decane under high hydrogen pressure (60 bars) at 260 deg C was chosen as a test reaction. The catalysts were prepared by two methods: mechanical mixing of the zeolite with alumina supported platinum and incipient wetness impregnation of platinum on the zeolite. It is shown that the proximity of acid and metallic sites in the latter leads to high yields of isomerization products. The amount and nature of the EFAI, and the meso-porous texture of the samples studied, have little influence on the catalytic properties (in terms of selectivity or acidity) of de-aluminated zeolite Y. Only the steamed zeolite shows in some conditions a lower activity and selectivity towards isomerized products. (author) 145 refs.

  2. Catalytic removal of sulfur dioxide from dibenzothiophene sulfone over Mg-Al mixed oxides supported on mesoporous silica.

    Science.gov (United States)

    You, Nansuk; Kim, Min Ji; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Jeon, Jong-Ki

    2010-05-01

    Dibenzothiophene sulfone (DBTS), one of the products of the oxidative desulfurization of heavy oil, can be removed through extraction as well as by an adsorption process. It is necessary to utilize DBTS in conjunction with catalytic cracking. An object of the present study is to provide an Mg-Al-mesoporous silica catalyst for the removal of sulfur dioxide from DBTS. The characteristics of the Mg-Al-mesoporous silica catalyst were investigated through N2 adsorption, XRD, ICP, and XRF. An Mg-Al-mesoporous silica catalyst formulated in a direct incorporation method showed higher catalytic performance compared to pure MgO during the catalytic removal of sulfur dioxide from DBTS. The higher dispersion of Mg as well as the large surface area of the Mg-Al-mesoporous silica catalyst strongly influenced the catalyst basicity in DBTS cracking. PMID:20359023

  3. 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:

  4. 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:……

  5. 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.

  6. 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.)

  7. Slow crack growth in polycarbonate films

    OpenAIRE

    Cortet, Pierre-Philippe; Santucci, Stéphane; Vanel, Loïc; 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 quantitat...

  8. The Simulation of Paint Cracking and Peeling

    OpenAIRE

    Paquette, Eric; Poulin, Pierre; Drettakis, George

    2002-01-01

    Weathering over long periods of time results in cracking and peeling of layers such as paint. To include these effects in computer graphics images it is necessary to simulate crack propagation, loss of adhesion, and the curling effect of paint peeling. We present a new approach which computes such a simulation on surfaces. Our simulation is inspired by the underlying physical properties. We use paint strength and tensile stress to determine where cracks appear on the surface. Cracks are then ...

  9. New Perspectives in Crack and Fault Dynamics

    OpenAIRE

    Rice, James R.

    2001-01-01

    Recent observations on the dynamics of crack and fault rupture are described, together with related theory and simulations in the framework of continuum elastodynamics. Topics include configurational instabilities of tensile crack fronts (crack front waves, disordering, sidebranching), the connection between frictional slip laws and modes of rupture propagation in earth faulting, especially conditions for formation of self-healing slip pulses, and the rich faulting and cracking phenomena that...

  10. 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.

  11. 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

  12. A Study on the Stress Corrosion Cracking of AISI 304 Stainless Steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking phenomenon of the commercial type 304 stainless steel wire in the boiling 42% magnesium chloride solution has been investigated. Main experimental techniques were to measure the time to failure of the wire varying the applied tensile stress, to follow potential of the material versus time, to observe potentiostatic polarization behavior, and to examine the microstructure of the failed specimens. Results showed that every crack propagates in the transgranular fashion. With the more applied stress up to 53,200 psi, the more crack density appeared per unit length of specimen and the less time was taken to the final fracture. The role of applied stress seemed to be involved both in the crack initiation and in the crack propagation, but more pronounced in the latter process. Potential vs. time curve and potentiostatic polarization behavior of the wire indicated that a passive film would be present on the corroding specimen surface. Breaking of such a film induced by strain due to the applied stress would initiate crack formation when anodic dissolution of the metal was followed at the resulting bare sites. It was found that crack propagation started at the base of a pit especially when large anodic current was forced to flow into the wire. A cathodic polarization to the potential slightly more active than the steady state corrosion potential retarded remarkably the time to failure of the wire specimen. Data revealed that such a slight cathodic protection was slowing down crack propagation

  13. 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

  14. 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

  15. 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.

  16. 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

  17. On Generating Fatigue Crack Growth Thresholds

    Science.gov (United States)

    Forth, Scott C.; Newman, James, Jr.; Forman, Royce G.

    2003-01-01

    The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. These experimental procedures can induce load history effects that result in crack closure. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake or blunt at the crack tip, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor range, Delta K, will increase, as will the crack growth rate. da/dN. A fatigue crack growth threshold test procedure is experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R. The authors have chosen to study a ductile aluminum alloy where the plastic deformations generated during testing may be of the magnitude to impact the crack opening.

  18. Effect of crack orientation statistics on effective stiffness of mircocracked solid

    DEFF Research Database (Denmark)

    Kushch, V.I.; Sevostianov, I.; Mishnaevsky, Leon

    2009-01-01

    This paper addresses the problem of calculating effective elastic properties of a solid containing multiple cracks with prescribed orientation statistics. To do so, the representative unit cell approach has been used. The microgeometry of a cracked solid is modeled by a periodic structure with a...... meaningful results obtained show dependence of the effective elastic stiffness on angular scattering of cracks. Comparison has been made with the selected simple micromechanical models, namely, non-interaction approximation, differential scheme and modified differential scheme. It is found that, among these...... models, the differential scheme provides the best fit of the numerical data. (C) 2008 Elsevier Ltd. All rights reserved....

  19. 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...

  20. 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)

  1. 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

  2. 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....

  3. 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....

  4. Evaluation on ultrasonic examination methods applied to Ni-base alloy weld including cracks due to stress corrosion cracking found in BWR reactor internal

    International Nuclear Information System (INIS)

    A Ni-base alloy weld, including cracks due to stress corrosion cracking found in the reactor internal of the oldest BWR in Japan, Tsuruga unit 1, in 1999, was examined by three (3) types of UT method. After this examination, a depth of each crack was confirmed by carrying out a little excavation with a grinder and PT examination by turns until each crack disappeared. Then, the depth measured by the former method was compared with the one measured by the latter method. In this fashion, performances of the UT methods were verified. As a result, a combination of the three types of UT method was found to meet the acceptance criteria given by ASME Sec.XI Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems-Supplement 6. In this paper, the results of the UT examination described above and their evaluation are discussed. (author)

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

    OpenAIRE

    In-Seok Yoon

    2012-01-01

    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 ...

  6. 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)

  7. 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.

  8. Factors controlling nitrate cracking of mild steel

    International Nuclear Information System (INIS)

    Nitrite and hydroxide ions inhibit the growth of nitrate stress corrosion cracks in mild steel. Crack growth measurements showed that sufficient concentrations of nitrite and hydroxide ions can prevent crack growth; however, insufficient concentrations of these ions did not influence the Stage II growth rate or the threshold stress intensity, but extended the initiation time. Stage III growth was discontinuous. Oxide formed in the grain boundaries ahead of the crack tip and oxide dissolution (Stage II) and fracture (Stage III) are the proposed mechanisms of nitrate stress corrosion crack growth

  9. 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 for...... the shear strength of disks with initial cracks and disks suffering from isotropic cracking are presented. Furthermore, in the case of isotropicly cracked disks subjected to arbitrary in-plane loading, a general yield condition is derived....

  10. 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)

  11. Barrel Bolt Cracking in a German PWR

    Energy Technology Data Exchange (ETDEWEB)

    Kilian, R.; Maussner, G. [AREVA GmbH (Germany); Koenig, G. [EnBW Kernkraft GmbH (Germany)

    2011-07-01

    In this paper, the results of failure analysis of cracked barrel bolts will be shown. The barrel bolts are made of German material number 1.4571 corresponding to 316 Ti. To ensure that the required mechanical properties are achieved, the material used was cold worked. At the end of the eighties, the bolts were installed to replace Inconel X- 750 bolts. The design used is a 'star bolt'. In 2005, cracking was first observed. In this report, the results of destructive examinations showing intergranular stress corrosion cracking will be presented. M16-Bolts exhibited cracking only in the area of cup, preventing unintentional loosening. All selected and examined M12-Bolts showed similar crack initiation in the head. Cracks may initiate on transition radii between the head and shank. The shank and thread of all bolts (M12 and M16) exhibited no indications of cracking. Bolts that experienced cracking could be clearly identified through visual inspection. The ultrasonic testing technique applied confirmed crack locations in the head. All cracks were attributed to Intergranular Stress Corrosion Cracking (IGSCC). Fracture surfaces exhibited relatively thin, dark layers and, in addition to corrosion products of the base metal, the debris on the shank and head also contained traces of Al, Si, Cu and Zn. (authors)

  12. Short cracks in piping and piping welds

    International Nuclear Information System (INIS)

    This program started on March 23, 1990, and has a duration of 4 years. The objective of the program is to develop and verify analyses by using existing and new experimental data for circumferentially cracked pipes, so modifications and improvements can be made to LBB and in-service flaw evaluation criteria. There are 7 technical tasks dealing, in general, with circumferentially cracked straight pipe under quasi-static loading. The tasks are as follows: short through wall cracked (TWC) pipe evaluations, short surface-cracked pipe evaluations, bi-metallic cracked pipe evaluations, dynamic strain aging and crack jump evaluations, anisotropic fracture evaluations, crack-opening-area evaluations, and NRCPIPE code improvements. There is also a separate task to develop international cooperation, interact with Section 11 of the ASME code, and perform program management functions

  13. 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)

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

    International Nuclear Information System (INIS)

    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)

  15. 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.

  16. Polygon/Cracked Sedimentary Rock

    Science.gov (United States)

    2004-01-01

    4 December 2004 Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0oS, 311.9oW. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.

  17. Catalytic DNA with phosphatase activity

    OpenAIRE

    Chandrasekar, Jagadeeswaran; Silverman, Scott K.

    2013-01-01

    Catalytic DNA sequences (deoxyribozymes, DNA enzymes, or DNAzymes) have been identified by in vitro selection for various catalytic activities. Expanding the limits of DNA catalysis is an important fundamental objective and may facilitate practical utility of catalysts that can be obtained from entirely unbiased (random) sequence populations. In this study, we show that DNA can catalyze Zn2+-dependent phosphomonoester hydrolysis of tyrosine and serine side chains (i.e., exhibit phosphatase ac...

  18. Fretting cracks in a 936 MW turbine generator rotor

    International Nuclear Information System (INIS)

    During the running down of a turbine on Unit 2 at Darlington Nuclear Power Plant in Canada, very serious shaft vibrations when the critical bending point was surpassed were measured on the generator bearings. During the subsequent inspection, a 400 mm long crack at the shaft end of the generator rotor was discovered. This paper describes the investigation of the cause of the damage and reports on the development of different solution concepts for the remaining rotors. One unit at the power plant has been running satisfactorily at full load for a long period. (orig.)

  19. Stress corrosion cracking in low-pressure steam turbines --An overview

    International Nuclear Information System (INIS)

    This paper presents an overview of stress corrosion cracking (SCC) in low-pressure (LP) turbine discs through 1993. Disc cracking experience in power plants and pertinent results of research programs are summarized. Analyses of field experiences and laboratory studies conducted in the United Kingdom, the United States, and other countries showed that stress corrosion cracking of LP turbine disc steels can occur in pure condensed steam or pure water, as well as in known cracking environments, such as hot hydroxide solutions. It has been established that stress corrosion crack initiation in LP turbine disc steels exposed to high-purity water environments typical of those found in nuclear power plants depends upon seven factors: the presence of a liquid phase; the oxygen concentration of the liquid phase (or the electrode potential corresponding to the oxygen concentration); the yield strength of the steel used in discs; the disc temperature; tensile stress level; crevices and localized corrosion within crevices; and a combination of tensile stress and a flaw of size and shape sufficient to produce a KI value greater than KISCC. While stress corrosion crack initiation depends upon the several factors listed above, the growth rate of stress corrosion cracks in LP turbine disc steels exposed to high-purity water and steam environments depends upon only three factors: the presence of a liquid phase; disc yield strength; and disc temperature. Importantly, stress corrosion crack growth rates in LP turbine disc steels are essentially independent of tensile stress level and stress intensity. Increase in both yield strength and temperature result in increased crack growth rate. 37 refs

  20. Hydrogen-induced cracking: 2

    International Nuclear Information System (INIS)

    There is a strong motivation for understanding the factors controlling zirconium hydride reorientation under stress because of the important role this plays in hydrogen-induced crack growth and/or crack initiation in zirconium and its alloys, particularly under thermal cycling conditions. Following an approach developed by Sauthoff, an analysis of the orienting effect of external stress on the nucleation, growth and coarsening of γ- and delta-zirconium hydride precipitates in zirconium and its alloys is presented. The analysis is based on a previous theoretical study of some of the factors affecting hydride solubility in stressed and unstressed solids. Expressions are derived for the effect of stress on nucleation, growth and coarsening. We conclude, on the basis of these that the preferential orientation of hydride precipitates under stress is most efficient during the nucleation stage. The reason for this is that the overall driving force for nucleation, for the chosen parameters and the usual experimental conditions, is fairly small. Therefore, the driving force for orientating under stress can be a substantial fraction of the overall driving force. The analysis shows that hydride growth is unlikely to play a role in preferential orientation, but coarsening could be important under carefully chosen experimental conditions, which may be relevant to the hydride-cracking process

  1. 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.

  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. Determination of the catalyst circulation rate in a FCC cold flow pilot unit using nuclear techniques

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Valdemir A. dos, E-mail: valdemir.alexandre@pq.cnpq.br [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil). Centro de Ciencias e Tecnologia; Dantas, Carlos C.; Melo, Silvio B., E-mail: ccd@ufpe.br, E-mail: sbm@cin.ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Lima, Emerson A.O., E-mail: eal@poli.br [Universidade de Pernambuco (UPE), Recife, PE (Brazil). Escola Politecnica

    2013-07-01

    Nuclear techniques of gamma transmission and radioactive tracer were used to estimate the catalyst circulation rate in a cold flow pilot plant unit of Fluid Catalytic Cracking (FCC). Catalyst circulation rate in a FCC unit, allow to determine operating conditions of the exchange catalyst and inlet data for fluid dynamic simulation computational program. The pilot unit was fabricated obeying geometrical parameters provided by the Petrobras Research Center (CENPES), based on hot pilot units to existing in that center. The cold flow pilot unit has a transfer line, two separation vessels flash type, a return column, a riser and a regenerator. The vertical sections as riser, return column, regenerator column and transfer line are made of transparent material (glass). The two separation vessels have bases with tapered cylindrical shapes and are made of steel plates. The riser is divided into four sections of different diameters (0.005 m, 0.010 m, 0.018 m and 0.025 m) and rising upwards, to simulate the increasing flow rate caused by the increase of volume with the increase of the number of moles due to molecules breakage. The radioactive tracer used was the catalyst itself (intrinsic tracer) irradiated by neutron activation, yielding the radioisotope {sup 59}Fe. The velocity measurements were also obtained with aid of an electronic clock triggered by certain radiation levels across the two detectors. Besides estimates for the catalyst circulation rate was possible to identify the type of flow relative to the catalyst in return column. (author)

  4. Determination of the catalyst circulation rate in a FCC cold flow pilot unit using nuclear techniques

    International Nuclear Information System (INIS)

    Nuclear techniques of gamma transmission and radioactive tracer were used to estimate the catalyst circulation rate in a cold flow pilot plant unit of Fluid Catalytic Cracking (FCC). Catalyst circulation rate in a FCC unit, allow to determine operating conditions of the exchange catalyst and inlet data for fluid dynamic simulation computational program. The pilot unit was fabricated obeying geometrical parameters provided by the Petrobras Research Center (CENPES), based on hot pilot units to existing in that center. The cold flow pilot unit has a transfer line, two separation vessels flash type, a return column, a riser and a regenerator. The vertical sections as riser, return column, regenerator column and transfer line are made of transparent material (glass). The two separation vessels have bases with tapered cylindrical shapes and are made of steel plates. The riser is divided into four sections of different diameters (0.005 m, 0.010 m, 0.018 m and 0.025 m) and rising upwards, to simulate the increasing flow rate caused by the increase of volume with the increase of the number of moles due to molecules breakage. The radioactive tracer used was the catalyst itself (intrinsic tracer) irradiated by neutron activation, yielding the radioisotope 59Fe. The velocity measurements were also obtained with aid of an electronic clock triggered by certain radiation levels across the two detectors. Besides estimates for the catalyst circulation rate was possible to identify the type of flow relative to the catalyst in return column. (author)

  5. Crack growth monitoring by strain measurements

    International Nuclear Information System (INIS)

    Cracks detected during in-service inspections are not always removed when they are judged as hazardous. It is important to monitor the crack growth in order to secure the integrity of the cracked components. The author and a co-worker proposed a crack growth monitoring method, in which the elastic strain caused by internal pressure is continuously measured. The elastic strain acting at the outside surface of a pressurized pipe changes due to growth of a crack in the inside surface, and the magnitude of its change depends on the growth size. In this study, the author uses multiple strain gages to monitor the elastic strain acting on the cracked part of a pipe. An axial crack was introduced at the butt welding portion inside a carbon steel pipe. The strains were then measured under static internal pressure. The crack size was estimated based on the change in strains measured by strain gages attached onto the outside surface of the pipe. This study reveals that such a monitoring procedure could successfully identify not only the crack depth but also the surface length. The maximum estimation errors were 2.2 mm and 0.97 mm for the surface length and depth, respectively. The accuracy of the estimation improved as the number of strain gages increased. It was also apparent that the residual stress had subtle effect on the size estimation, albeit it may have significant influence when the crack propagates. (author)

  6. Management of stress corrosion cracking in pressurized water reactors

    International Nuclear Information System (INIS)

    Stress Corrosion Cracking (SCC) has recently become a significant issue for pressurized water reactors (PWR) in the United States (US). Until recently, SCC in primary coolant piping systems in nuclear reactors was thought to be an issue only for Boiling Water Reactors (BWR) caused by the aggressive BWR environment, susceptible material (austenitic stainless steel) and high stresses, all of which occurred in the vicinity of pipe and nozzle weldments. However, with the discovery of stress corrosion cracking [(denoted as primary water stress corrosion cracking (PWSCC)] at several PWR plants over the past 5 years, the first being at V.C. Summer in South Carolina, the issue has become significant for the US PWR industry. Because of the significant amount of experience gained in managing SCC over the past few years, it clear that implementing a well planned proactive aging management program can be important in minimizing interruptions to plant operation due to unexpected component degradation. Implementation of aging management programs (Plant Life Management) can help minimize the impact of SCC on plant availability and safety. An effective plant management program considers the mitigation, monitoring, inspection, repair and replacement activities related to PWR SCC. This paper summarizes the PWR SCC issue in the United States including historical, regulatory, industry activities and general recommendations/approaches to manage potential degradation. (author)

  7. Crack detection sensor layout and bus configuration analysis

    International Nuclear Information System (INIS)

    In crack detection applications large sensor arrays are needed to be able to detect and locate cracks in structures. Emerging graphene-oxide paper sensing skins are a promising technology that will help enable structural sensing skins, but in order to make use of them we must consider how the sensors will be laid out and wired on the skin. This paper analyzes different sensor shapes and layouts to determine the layout which provides the preferred performance. A ‘snaked hexagon’ layout is proposed as the preferred sensor layout when both crack detection and crack location parameters are considered. In previous work we have developed a crack detection circuit which reduces the number of channels of the system by placing several sensors onto a common bus line. This helps reduce data and power consumption requirements but reduces the robustness of the system by creating the possibility of losing sensing in several sensors in the event that a single wire breaks. In this paper, sensor bus configurations are analyzed to increase the robustness of the bused sensor system. Results show that spacing out sensors in the same bus as much as possible increases the robustness of the system and that at least 3 buses are needed to prevent large segments of a structure from losing sensing in the event of a bus failure. This work is a preliminary effort toward enabling a new class of ‘networked materials’ that will be vitally important for next generation structural applications. ‘Networked materials’ have material properties related to information theoretic concepts. An example material property is ‘bandwidth’ per unit of material that might indicate the amount of information the material can provide about its state-of-health. (paper)

  8. Effects of δ-hydride precipitation at a crack tip on crack propagation in delayed hydride cracking of Zircaloy-2

    International Nuclear Information System (INIS)

    Highlights: • Steady state crack velocity of delayed hydride cracking in Zircaloy-2 was analyzed. • A large stress peak is induced at an end of hydride by volume expansion of hydride. • Hydrogen diffuses to the stress peak, thereby accelerating steady hydride growth. • Crack velocity was estimated from the calculated hydrogen flux into the stress peak. • There was good agreement between calculation results and experimental data. -- Abstract: Delayed hydride cracking (DHC) of Zircaloy-2 is one possible mechanism for the failure of boiling water reactor fuel rods in ramp tests at high burnup. Analyses were made for hydrogen diffusion around a crack tip to estimate the crack velocity of DHC in zirconium alloys, placing importance on effects of precipitation of δ-hydride. The stress distribution around the crack tip is significantly altered by precipitation of hydride, which was strictly analyzed using a finite element computer code. Then, stress-driven hydrogen diffusion under the altered stress distribution was analyzed by a differential method. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed in front of the crack tip, it grew almost steadily accompanying the interaction of hydrogen diffusion, hydride growth and the stress alteration by hydride precipitation. Finally, crack velocity was estimated from the calculated hydrogen flux into the crack tip as a function of temperature, stress intensity factor and material strength. There was qualitatively good agreement between calculation results and experimental data

  9. 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.

  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. 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

  12. 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.

  13. 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.

  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. Constraint effects of clad on underclad crack

    International Nuclear Information System (INIS)

    The finite element method is applied to two-dimensional elastic-plastic analyses for underclad crack problems. The analyses are performed for rectangular specimens with an underclad crack, which are composed of A533B class 1 steel and a clad material, to obtain the fracture mechanics parameter J-integral and the stress distribution ahead of a crack tip. The Q-factor proposed by O'Dowd and Shih is calculated from the stress distribution ahead of a crack tip, and the constraint effect of a crack tip due to a clad material or the effect of a clad material on the fracture toughness of a base material is discussed in terms of the Q-factor. Clad thickness, crack length and the material property of a clad material are varied to examine their effects

  16. 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

  17. Scaling of crack propagation in rubber sheets

    Science.gov (United States)

    Chen, C. H.; Zhang, H. P.; Niemczura, J.; Ravi-Chandar, K.; Marder, M.

    2011-11-01

    We have conducted experiments and numerical simulations to investigate supersonic cracks. The experiments are performed at 85 °C to suppress strain-induced crystallites that complicate experiments at lower temperature. Calibration experiments were performed to obtain the parameters needed to compare with a theory including viscous dissipation. We find that both experiments and numerical simulations support supersonic cracks, and we discover a transition from subsonic to supersonic as we plot experimental crack speed curves vs. extension ratio for different sized samples. Both experiments and simulations show two different scaling regimes: the speed of subsonic cracks scales with the elastic energy density while the speed of supersonic cracks scales with the extension ratio. Crack openings have qualitatively different shapes in the two scaling regimes.

  18. 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.

  19. 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

  20. TRAC-BF1 thermal-hydraulic, ANSYS stress analysis for core shroud cracking phenomena

    International Nuclear Information System (INIS)

    The U.S. Nuclear Regulatory Commission sent Generic Letter 94-03 informing all licensees about the intergranular stress corrosion cracking (IGSCC) of core shrouds found in both Dresden unit I and Quad Cities unit 1. The letter directed all licensees to perform safety analysis of their boiling water reactor (BWR) units. Two transients of special concern for the core shroud safety analysis include the main steam line break (MSLB) and recirculation line break transient

  1. 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.

  2. Swedes repair BWR thermal fatigue cracks

    International Nuclear Information System (INIS)

    The discovery of cracks in the feedwater and shutdown cooling systems of Sweden's Barseback 2 BWR in 1980 led to investigations in other Swedish nuclear power stations. Similar cracks were found and the defective parts repaired or replaced before being returned to service. The cause of the cracks has been evaluated and efforts are being made to prevent a recurrence. Experience with Ringhals 1, Orkarsham 2 and Forsmark 1 systems are also described. (author)

  3. 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.

  4. Paths of interactive cracks in creep conditions

    OpenAIRE

    Nowak, K.

    2015-01-01

    The paper contains plane strain analysis of uniformly stretched plate working in creep condition. The plate contains initial defects in forms of central and/or edge cracks working in mode I. These cracks are modelled by attributing critical value of damage parameter to preset points and therefore resulting in stresses set to zero (material does not support any loading). The Continuum Damage Mechanics constitutive equations are used to describe the creep crack growth problem and Fi...

  5. Measuring Crack Length in Coarse Grain Ceramics

    Science.gov (United States)

    Salem, Jonathan A.; Ghosn, Louis J.

    2010-01-01

    Due to a coarse grain structure, crack lengths in precracked spinel specimens could not be measured optically, so the crack lengths and fracture toughness were estimated by strain gage measurements. An expression was developed via finite element analysis to correlate the measured strain with crack length in four-point flexure. The fracture toughness estimated by the strain gaged samples and another standardized method were in agreement.

  6. Hydrogen induced cracking of Grade-2 titanium

    International Nuclear Information System (INIS)

    Titanium is one of the container material options in the Canadian Nuclear Fuel Waste Management Program. This material has very good corrosion resistance under the anticipated disposal conditions. The two most likely corrosion failure mechanisms are crevice corrosion and hydrogen assisted cracking. Crevice corrosion is a possibility in the warm saline environment proposed for a nuclear disposal vault, and its propagation will lead to a local production of hydrogen in the crevice. Many high-strength titanium alloys can absorb hydrogen into the metal and, when subjected to low but long-term sustained loads, become susceptible to delayed hydrogen cracking at low hydrogen concentrations. In this work, the slow strain rate technique was used to accelerate the cracking process in Grade-2 titanium in order to establish the relative conditions where delayed hydrogen cracking might be possible. The results indicate that at low hydrogen concentrations, slow crack growth occurs by a ductile tearing process. No fast crack growth is observed at these low hydrogen concentrations, presumably because the ductile collapse relaxes the stresses and prevents the attainment of a sufficiently high stress intensity for fast crack growth. Fast crack growth was observed only at hydrogen concentrations above a critical value that ranged from 310-1380 wppm hydrogen depending upon the plate material studied and the orientation of the crack relative to the manufactured microstructure. An empirical relationship suggests that the higher the strength of the titanium material the lower the critical hydrogen concentration. The report describes the effects of microstructure on the cracking behaviour of Grade-2 titanium and shows that the crack propagation tends to follow the directionality of the microstructure introduced by rolling during its manufacture. Increasing the temperature to 100 deg C increased the critical hydrogen concentration to >2000 wppm hydrogen, suggesting that the slow crack

  7. 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.

  8. Crack growth of intergranular stress corrosion cracks in austenitic stainless steel pipes of boiling water reactors

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (IGSCC) of boiling water reactor (BWR) piping is considered from the crack growth rate point of view. Crack growth rate of sensitized austenitic stainless steel welds is dependent on the degree of sensitization of the material and the severity of the environment as well as the stress state. In evaluation of actual crack growth rate there are three major sources of uncertainty: knowledge of actual crack size and shape, actual stress distribution in he area of the crack and the degree of sensitization. In the report the crack growth calculations used in the USA and in Sweden are presented. Finally, the crack growth rate predictions based on mechanistic modelling of IGSCC and some needs of further research in Finland are considered

  9. Modelling of environmentally assisted cracking

    International Nuclear Information System (INIS)

    During the use of nuclear reactors the properties of the structural materials change. Variations in the operation environment, such as changes in water chemistry, may enhance the development and growth of flaws. Neutron radiation causes embrittlement for in-core vessel materials. Radiation, together with water chemistry, increases the possibility of stress corrosion cracking in stainless steels and superalloys used in the reactor internal parts. Research on structural materials endeavours to study the ageing mechanisms of materials, and the possibilities and methods of preventing or forecasting the damage caused to structures by ageing. (orig.)

  10. 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.)

  11. Correlation between segregation and cold cracking

    International Nuclear Information System (INIS)

    An attempt is made to find a correlation between segregation in ferritic base metal and the occurrence of cold cracking. Besides describing the mechanical and engineering properties and chemical composition of the segregated areas, the paper discusses their behaviour when welded over. Characteristics and models of crack development are presented using cold cracking found in various components as an example. Suitable measures for limiting the risk of the occurrence of cold cracking are increasing the pre-heating temperature, use of weld filler material with optimum dryness, and heat treatment directly following welding. (author)

  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. 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.

  14. T-stresses for internally cracked components

    International Nuclear Information System (INIS)

    The failure of cracked components is governed by the stresses in the vicinity of the crack tip. The singular stress contribution is characterised by the stress intensity factor K, the first regular stress term is represented by the so-called T-stress. T-stress solutions for components containing an internal crack were computed by application of the Bundary Collocation Method (BCM). The results are compiled in form of tables or approximative relations. In addition a Green's function of T-stresses is proposed for internal cracks which enables to compute T-stress terms for any given stress distribution in the uncracked body. (orig.)

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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].

  2. 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....

  3. 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.

  4. 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.

  5. Effect of aluminium distribution in the framework of ZSM-5 on hydrocarbon transformation. Cracking of 1-butene

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Dědeček, Jiří; Gábová, Vendula; Wichterlová, Blanka; Spoto, G.; Bordiga, S.

    2008-01-01

    Roč. 254, č. 2 (2008), s. 180-189. ISSN 0021-9517 R&D Projects: GA AV ČR IAA4040308; GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : H-ZSM-5 * Al destribution * catalytic cracking * zeolite acidity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.167, year: 2008

  6. 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...

  7. 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.

  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. 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.

  10. 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.

  11. BWR pipe crack remedies evaluation

    International Nuclear Information System (INIS)

    This paper presents results on: (a) the influence of simulated BWR environments on the stress-corrosion-craking (SCC) susceptibility of Types 304, 316NG, and 347 stainless (SS); (b) fracture-mechanics crack-growth-rate measurements on these materials and weld overlay specimens in different environments; and (c) residual stress measurements and metallographic evaluations of conventional pipe weldments treated by a mechanical-stress-improvement process (MSIP) as well as those produced by a narrow-gap welding procedure. Crack initiation studies on Types 304 and 316NG SS under crevice and non-crevice conditions in 2890C water containing 0.25 ppM dissolved oxygen with low sulfate concentrations indicate that SCC initiates at very low strains (0 in both directions, and then grew at high rate (parallel to the nominal applied load). Residual stress measurements on MSIP-treated weldments and those produced by a narrow-gap welding procedure indicate that these techniques produce compressive stresses over most of the inner surface near the weld and heat-affected zones

  12. 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.

  13. Laboratory Study of Crack Development and Crack Interaction in Concrete Blocks due to Swelling of Cracking Agent

    Science.gov (United States)

    Frühwirt, Thomas; Plößer, Arne; Konietzky, Heinz

    2015-04-01

    The main focus of this work was to investigate temporary and spatial features of crack development in concrete blocks due to the action of a swelling agent. A commercial available cement-based mortar which shows heavily swelling behaviour when hydrating is used to provide inside pressure in boreholes in conrete blocks and hence serves as cracking agent. As no data for the swelling behaviour of the cracking agent were available the maximum axial swelling stress and axial free swelling strain were determined experimentally. In a first series of tests on concrete blocks the influence of an external mechanical, unidirectional stress on the development-time and orientation of cracks has been investigated for a range of loading levels. The stress state in the blocks prepared with a single borehole was determined by a superposition of internal stresses caused by swelling pressure and external mechanical loading. For a second series of tests prismatic blocks with two boreholes where prepared. This test setup allowed to realize different orientation of boreholes with respect to the uniaxial loading direction. Complementary tests were done using the cracking agent in both, only one or none of the boreholes. Different modes of crack interaction and influence of filled or unfilled boreholes have been observed. Features of crack development showed significant sensitivity to external loading. Starting even at very low load levels crack orientation was primarely determined by the direction of the external load. Temporal change in crack development due to the different load levels was insignificant and no consistent conclusion could be drawn. Crack interaction phenomena only were observed with two boreholes orientated primarely in direction of the external loading. Even in these cases crack orientation was mainly determined by the external stress field and only locally influenced by other cracks or the unfilled borehole. The work provides us with an extensive catalogue of

  14. 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.

  15. Optimization of Reactor Temperature and Catalyst Weight for Plastic Cracking to Fuels Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2011-01-01

    Full Text Available The present study deals with effect of reactor temperature and catalyst weight on performance of plastic waste cracking to fuels over modified catalyst waste as well as their optimization. From optimization study, the most operating parameters affected the performance of the catalytic cracking process is reactor temperature followed by catalyst weight. Increasing the reactor temperature improves significantly the cracking performance due to the increasing catalyst activity. The optimal operating conditions of reactor temperature about 550 oC and catalyst weight about 1.25 gram were produced with respect to maximum liquid fuel product yield of 29.67 %. The liquid fuel product consists of gasoline range hydrocarbons (C4-C13 with favorable heating value (44,768 kJ/kg. ©2010 BCREC UNDIP. All rights reserved(Received: 10th July 2010, Revised: 18th September 2010, Accepted: 19th September 2010[How to Cite: I. Istadi, S. Suherman, L. Buchori. (2010. Optimization of Reactor Temperature and Catalyst Weight for Plastic Cracking to Fuels Using Response Surface Methodology. Bulletin of Chemical Reaction Engineering and Catalysis, 5(2: 103-111. doi:10.9767/bcrec.5.2.797.103-111][DOI: http://dx.doi.org/10.9767/bcrec.5.2.797.103-111 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/797

  16. Formation and application of Nano Noble metal particles to mitigate stress corrosion cracking in BWR

    International Nuclear Information System (INIS)

    Boiling water nuclear reactors (BWRs) throughout the world have applied the NobleChem™ (or noble metal chemical addition: NMCA) or Online NMCA (OLNC) process just before end-of-cycle shutdown or during an operation to mitigate the stress corrosion cracking (SCC) of structural materials in BWRs. When injected into BWR environments, the noble metal particles deposit on Type 304 stainless steel surfaces and reduce the corrosion potential, which decreases the propensity for SCC. Very fine noble metal particles are formed and able to potentially deposit inside a crack and maintain catalytic surfaces in the critical regions inside the crack. This paper demonstrates the sonochemical method for producing Pt nanoparticles and describes the feasibility of using noble metal nanoparticles to mitigate the stress corrosion cracking of structural materials in BWRs , called Nano NobleChem™. Several methods were explored to create Pt nanoparticles by the high intensity sonication of micron size of Pt and PtO2. This new approach would also enable the application of noble metal technology while the reactor is in operation. (author)

  17. Shimane Nuclear Power Station Unit 1, the results of cutting investigation into defective part of pipe of primary loop recirculation system

    International Nuclear Information System (INIS)

    At Shimane Nuclear Power Station Unit 1 (BWR, electric output 460 thousand kilowatts, the 29th Periodic Inspection conducting from November 8, 2010), Cracks were found at pipe of PLR by Ultrasonic Testing. Investigation of cutting pipe was conducted for extending our knowledge because these cracks were relatively longer than crack until now. As the result of this investigation, it was confirmed that this defective part was not a long crack but multi short cracks. It can be thought that because multi short cracks were adjacently, multi cracks make progress and become obvious. Therefore, it was confirmed that this case was within the knowledge we had. (author)

  18. 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.

  19. 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...

  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. Entering a Crack: An Encounter with Gossip

    Science.gov (United States)

    Henderson, Linda

    2014-01-01

    In this paper, I enter a crack to think otherwise about the concept "gossip". Drawing on previous scholarship engaging with Deleuzian concepts to inform research methodologies, this paper builds on this body of work. Following Deleuze and Guattari, the paper undertakes a mapping of gossip, subsequent to an encounter with a crack.…

  2. Fracture Mechanical Markov Chain Crack Growth Model

    DEFF Research Database (Denmark)

    Gansted, L.; Brincker, Rune; Hansen, Lars Pilegaard

    1991-01-01

    On the basis of the B-model developed in [J. L. Bogdanoff and F. Kozin, Probabilistic Models of Cumulative Damage. John Wiley, New York (1985)] a new numerical model incorporating the physical knowledge of fatigue crack propagation is developed. The model is based on the assumption that the crack...

  3. 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.)

  4. 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....

  5. 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.

  6. 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....

  7. Crack initiation under generalized plane strain conditions

    International Nuclear Information System (INIS)

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

  8. 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)

  9. 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.

  10. Prediction of crack onset strain in composite laminates at mixed mode cracking

    International Nuclear Information System (INIS)

    Failure process of continuous fiber reinforced composite laminates in tension usually starts with appearance of intralaminar cracks. In composite laminates with complex lay-ups and/or under combined loading, intralaminar cracks may develop in plies with different reinforcement directions. A necessary part of mixed mode cracking models is the criterion of failure. For propagation-controlled fracture it is usually formulated in terms of energy release rates and their critical values of the particular composite material. Intralaminar fracture toughness of unidirectionally reinforced glass/epoxy composite was experimentally determined at several mode I and mode II ratios. It is found that the crack propagation criterion, linear in terms of the energy release rates, reasonably well approximates the test results. The determined mixed mode cracking criterion was applied to predict intralaminar crack onset in cross-ply glass/epoxy composite under tensile loading. The predicted crack onset strain values agree with test results at small off-axes angles of the cracking ply (on-axis and 150 off-axis loading), but underestimate crack onset at larger reinforcement angles with respect to the loading direction. The discrepancy is likely to be caused by the deviation of linearity in laminate response before cracking onset in these laminates, related to non-linear shear characteristics of unidirectional plies. The applicability of strength-based fracture criterion for initiation-controlled cracking is discussed.

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

    International Nuclear Information System (INIS)

    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%

  12. 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%.

  13. 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...... low as 15 mg/Nm3 was obtained on gas from an updraft gasifier. The lower heating value of the cleaned gas was 6.0 MJ/Nm3, and the energy content of the non condensable gasses was 19% higher than before cracking....... was 1200, 1250 and 1290°C, and the residence time at this temperature was 0.5 second. The measurements show that at the selected residence time of 0.5 second, the gas flow in a thermal tar cracking unit has to be heated to at least 1250°C to achieve sufficient tar cleaning. At 1290°C, a tar content as...

  14. 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.

  15. 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

  16. 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。

  17. 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.

  18. 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

  19. Stress-corrosion cracking studies in coal-liquefaction systems

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.; Keiser, J.R.

    1981-01-01

    Coal liquefaction plants with 6000 ton/d capacity are currently being planned by DOE as a step toward commercial production of synthetic fossil fuels. These plants will demonstrate the large-scale viability of the Solvent Refined Coal (SRC) process, which has been used since 1974 in two operating pilot plants: a 50-ton/d unit at Fort Lewis, Washington, and a 6-ton/d plant in Wilsonville, Alabama. Experience in these plants has shown that austenitic stainless steels are susceptible to stress corrosion cracking associated with residual stresses from cold working or welding. The corrodants responsible for the cracking have not yet been positively identified but are suspected to include polythionic acids and chlorides. To screen candidate materials of construction for resistance to stress corrosion cracking, racks of stressed U-bend specimens in welded and as-wrought conditions have been exposed at the Wilsonville and Fort Lewis SRC pilot plants. These studies have identified alloys that are suitable for critical plant applications.

  20. 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

  1. 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.

  2. Stress-corrosion cracking in metals

    Science.gov (United States)

    1971-01-01

    Criteria and recommended practices for preventing stress-corrosion cracking from impairing the structural integrity and flightworthiness of space vehicles are presented. The important variables affecting stress-corrosion cracking are considered to be the environment, including time and temperature; metal composition, and structure; and sustained tensile stress. For designing spacecraft structures that are free of stress-corrosion cracking for the service life of the vehicle the following rules apply: (1) identification and control of the environments to which the structure will be exposed during construction, storage, transportation, and use; (2) selection of alloy compositions and tempers which are resistant to stress-corrosion cracking in the identified environment; (3) control of fabrication and other processes which may introduce residual tensile stresses or damage the material; (4) limitation of the combined residual and applied tensile stresses to below the threshold stress level for the onset of cracking throughout the service life of the vehicle; and (5) establishment of a thorough inspection program.

  3. Process and device for magnetic crack testing

    International Nuclear Information System (INIS)

    There is a problem of sufficient crack depth discrimination to suppress fault signals or pictures due to unevenness not caused by cracks. To solve this, when magnetising in the preferred direction of adhesion, the effect depending on the direction of the crack, before magnetic powder detection, magnetic powder is blown on, showing the fault and for the comparison of the adhesion effect crack direction characteristics it is blown on parallel to the preferred direction, or if one wants to stress the directional characteristic, it is blown on transversely to the preferred direction. In both cases one blows with the same force, without removing the magnetic powder remnants relevant to faults in the intended crack areas. This strong blowing removes the magnetic powder remnants relevant to interference and not relevant to faults. (orig./HP)

  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 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.

  6. TESTING OF FLOW THROUGH STRESS CORROSION CRACKS

    International Nuclear Information System (INIS)

    One aspect of licensing the high-level nuclear waste repository to be located at Yucca Mountain, Nevada, is the determination of the inclusion of the effects of features, events, and processes (FEPs) on the performance of the repository. Among the FEPs evaluated are the advection of solids and liquids through stress corrosion cracks in waste packages and drip shields. The presence of one or more cracks or other small openings of sufficient size in a waste package or drip shield may provide a pathway for the advective flow of water (e.g., thin films or droplets) or solid material through a waste package or drip shield. The resulting flux may affect drip shield performance and/or subsequent dripping onto or into the waste packages. The objective of this set of tests involved the detection/non-detection of advective water flow through stress cracks similar to those that may occur in the drip shield or waste package. If sufficient flow volume was present then attempts were made to quantify the volume of water flow through a stress crack. Literature was reviewed to identify previous studies and models that may be relevant to the current study of flow through stress corrosion cracks in a drip shield or waste package. Although no studies could be found that were directly applicable to our current problem, studies were identified that investigated portions of the overall problem. The papers that were reviewed were organized into the following categories: (1) maximum static head in a crack; (2) liquid impingement on surfaces [1]; (3) leakage through stress cracks [2]; and (4) dripping from cracks and fractures [3]. Because of the unique configuration and processes associated with the current problem of flow through stress corrosion cracks in drip shields and waste packages, experimental studies are needed to better understand whether flow can occur in stress cracks from impinging water droplets

  7. 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

  8. 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)

  9. Development of leak-free vessels against holes and cracks

    International Nuclear Information System (INIS)

    This paper proposes a method for obtaining the vessel, such that no fluid is leaked when holes or cracks occur, because the broken part is repaired automatically by its self-repairing mechanism. The self-repairing unit (sealant layer) is consisting of two rubber sheets with quilting processed. Polymer particles, which expand their volume in contact with water, produce the force for selfrepairing. This article first discusses a method for making the vessel, then the method is applied to a tire with large inside pressure. (author)

  10. Confirmation test of IHSI for pipe with crack

    International Nuclear Information System (INIS)

    This study is confirmed IHSI which is one of preventive maintenance techniques for stress corrosion cracking, can be applied to pipe with crack. The results were applicable under certain conditions by the test which was used pipe with 3 / 8 depth crack. Following four items were confirmed by this test. 1. Not affect for cracks and joints, 2. Residual stress would be improved with the tip of the crack and can be suppressed with crack growth, 3. Residual stress would be improved around the crack, 4. It can be effective for preventing SCC at non crack area. (author)

  11. Hot cracking studies on CrMoV and NiCrMoV turbine rotor steels during welding

    International Nuclear Information System (INIS)

    Four different rotor materials, three CrMoV steels and a NiCrMoV steel, were investigated both with respect to solidification and HAZ liquation cracking. It involved the Varestraint testing using autogeneous gas tungsten arc welding at two different heat inputs, and metallographic examinations using optical, scanning and/or transmission electron microscopy. An increase in heat input/unit length (from 1.2 to 2.7 KJ/mm) or an increase in travel speed at the same low heat input (1.2 KJ/mm) tends to produce more solidification cracking. In the case of CrMoV steels, 1950s air melted rotors (Buck and the Gallatin rotors) showed worse solidification cracking susceptibility than the modern Bethlehem forging vacuum poured, 2A. The modern NiCrMoV forging, also vacuum-poured, 3A, however, showed worse solidification cracking susceptibility than the old air-melted Gallatin rotor. Therefore, the harmful effects of Ni on solidification cracking was confirmed. Its role is understood as having favored the austenite formation, thus resulting in more primary austenite solidification. This gives rise to heavy segregation of impurities such as S and P at the austenite grain boundaries. Detrimental effects of sulfur and phosphorus both on solidification and the HAZ hot cracking were confirmed. Addition of Ce or Ti to the Buck rotor with the greatest solidification cracking susceptibility helped improve cracking resistance

  12. Hot cracking studies on CrMoV and NiCrMoV turbine rotor steels during welding

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, S.Y.

    1986-01-01

    Four different rotor materials, three CrMoV steels and a NiCrMoV steel, were investigated both with respect to solidification and HAZ liquation cracking. It involved the Varestraint testing using autogeneous gas tungsten arc welding at two different heat inputs, and metallographic examinations using optical, scanning and/or transmission electron microscopy. An increase in heat input/unit length (from 1.2 to 2.7 KJ/mm) or an increase in travel speed at the same low heat input (1.2 KJ/mm) tends to produce more solidification cracking. In the case of CrMoV steels, 1950s air melted rotors (Buck and the Gallatin rotors) showed worse solidification cracking susceptibility than the modern Bethlehem forging vacuum poured, 2A. The modern NiCrMoV forging, also vacuum-poured, 3A, however, showed worse solidification cracking susceptibility than the old air-melted Gallatin rotor. Therefore, the harmful effects of Ni on solidification cracking was confirmed. Its role is understood as having favored the austenite formation, thus resulting in more primary austenite solidification. This gives rise to heavy segregation of impurities such as S and P at the austenite grain boundaries. Detrimental effects of sulfur and phosphorus both on solidification and the HAZ hot cracking were confirmed. Addition of Ce or Ti to the Buck rotor with the greatest solidification cracking susceptibility helped improve cracking resistance.

  13. 2-METHYLHEXANE CRACKING ON Y-ZEOLITES: CATALYTIC CYCLES AND REACTION SELECTIVITY. (R825370C056)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  14. CATALYTIC CYCLES FOR HYDROCARBON CRACKING ON ZEOLITES. (R825370C056)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  15. An experimental study of cyclone dipleg flow in fluidized catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Bouma, J.H. [Twente Univ., Enschede (Netherlands). Dept. of Mech. Eng.; Dries, H. [Shell Global Solutions, Amsterdam (Netherlands)

    2000-10-31

    An experimental study was carried out on the downflow of fine catalysts (d{sub 50}=44 {mu}m) in a straight vertical cyclone dipleg (diameter 80 mm, height 4.6 m) to clarify various types of powder flow which can exist in the dipleg and to measure the amount of gas entrainment down the dipleg under a wide range of operating conditions. In addition, the radial profiles of solids velocity and solids volume fraction were measured at various heights along the dipleg. The axial pressure profiles show that the flow in the dipleg can be divided in regions: inlet, dilute and dense. A flow diagram shows the occurrence of various flow types depending on operating conditions. The flow in the dense region can be fluidized (preferred) or packed. In the dilute region, the solids velocity is higher than the terminal falling velocity of a single particle. This indicates the existence of clusters, the size of which has been estimated. Gas carry-under is generally not significant when the dense region has developed. Once there is a dilute region only, the gas carry-under can become as large as 20 times the volumetric solids flow. The radial profiles of solids velocity and solids volume fraction show that going from dipleg top to dipleg bottom, the rotating annular flow at the dipleg top (cyclon outlet) transforms into a more or less uniform plug flow, both with respect to velocity and to local concentration. (orig.)

  16. Using spent fluid catalytic cracking (FCC) catalyst as pozzolanic addition — a review

    OpenAIRE

    Nancy Torres Castellanos; Janneth Torres Agredo

    2010-01-01

    El catalizador gastado de craqueo catalítico (FCC) es un residuo procedente de las unidades de ruptura catalítica en le- cho fluido de la industria del petróleo. Este residuo está con- formado principalmente por un componente activo (zeolita y - tipo faujasita) en una matriz de aluminosilicato amorfo. Su composición química es básicamente sílice y alúmina en porcentajes hasta de un 90%. En este artículo se presenta una amplia revisión de diferentes investigaciones realizadas sobre la caracter...

  17. A comparison of stress in cracked fibrous tissue specimens with varied crack location, loading, and orientation using finite element analysis.

    Science.gov (United States)

    Peloquin, John M; Elliott, Dawn M

    2016-04-01

    Cracks in fibrous soft tissue, such as intervertebral disc annulus fibrosus and knee meniscus, cause pain and compromise joint mechanics. A crack concentrates stress at its tip, making further failure and crack extension (fracture) more likely. Ex vivo mechanical testing is an important tool for studying the loading conditions required for crack extension, but prior work has shown that it is difficult to reproduce crack extension. Most prior work used edge crack specimens in uniaxial tension, with the crack 90° to the edge of the specimen. This configuration does not necessarily represent the loading conditions that cause in vivo crack extension. To find a potentially better choice for experiments aiming to reproduce crack extension, we used finite element analysis to compare, in factorial combination, (1) center crack vs. edge crack location, (2) biaxial vs. uniaxial loading, and (3) crack-fiber angles ranging from 0° to 90°. The simulated material was annulus fibrosus fibrocartilage with a single fiber family. We hypothesized that one of the simulated test cases would produce a stronger stress concentration than the commonly used uniaxially loaded 90° crack-fiber angle edge crack case. Stress concentrations were compared between cases in terms of fiber-parallel stress (representing risk of fiber rupture), fiber-perpendicular stress (representing risk of matrix rupture), and fiber shear stress (representing risk of fiber sliding). Fiber-perpendicular stress and fiber shear stress concentrations were greatest in edge crack specimens (of any crack-fiber angle) and center crack specimens with a 90° crack-fiber angle. However, unless the crack is parallel to the fiber direction, these stress components alone are insufficient to cause crack opening and extension. Fiber-parallel stress concentrations were greatest in center crack specimens with a 45° crack-fiber angle, either biaxially or uniaxially loaded. We therefore recommend that the 45° center crack case be

  18. Model analysis of fatigue crack growth during EN 13262 wheel standard testing

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Náhlík, Luboš; Knésl, Zdeněk; Kunz, Ludvík; Matušek, P.

    Praha : Bonatrans, 2007, s. 97-110. [International Wheelset Congress /15./. Praha (CZ), 23.09.2007-27.09.2007] R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : EN 13262 Standard * fatigue * full-scale testing unit * crack growth * fatigue lifetime Subject RIV: JL - Materials Fatigue, Friction Mechanics

  19. Molecular dynamics investigation of dynamic crack stability

    International Nuclear Information System (INIS)

    A series of molecular-dynamics simulations has been performed in order to evaluate the effects of several physical factors on dynamic crack stability. These factors are the crystalline structure and the interatomic interaction modeled by various empirical potentials. For brittle crack propagation at low temperature we find that steady-state crack velocities are limited to a band of accessible values. Increasing the overload beyond KIc, the crack can propagate with a steady-state velocity, which quickly reaches the terminal velocity of about 0.4 of the Rayleigh wave speed. The magnitude of the terminal velocity can be related to the nonlinearity of the interatomic interaction. Further increasing the overload does not change the steady-state velocity dramatically, but significantly increases the amplitude of acoustic emission from the crack tip. Loading the crack even further leads to instabilities which take the form of cleavage steps, dislocation emission, or branching. The instability is closely related to the buildup of a localized coherent, phononlike field generated by the bond-breaking events. The form of the instability depends critically on crystal structure and on the crystallographic orientation of the crack system but can also be correlated with the relative ease of dislocation generation (and motion). copyright 1997 The American Physical Society

  20. Comparisons of inelastic J and J* evaluations for the blunt crack and the sharp crack models

    International Nuclear Information System (INIS)

    Concrete cracking is an important consideration in assessing the safety of a liquid metal fast breeder reactor (LMFBR) plant under a hypothetical accident where molten metal may come into contact with concrete structures. At the present time, several options in modeling concrete cracking have been pursued in an ongoing research program at Argonne National Laboratory which encompasses many aspects of high temperature behavior of concrete. Main emphasis is currently given to the blunt crack model where the crack is assumed to be uniformly distributed throughout the area of an element, though the sharp crack model is still kept as an alternative option where the crack surface is treated as the boundary of the finite element mesh. Several crack propagation criteria have been considered. Among these is the development of the J-integral approach with the blunt crack model. Numerical results were compared with those of the sharp crack model and found to be in good agreement for the elastic problem of a mode I crack. In this paper, the J-integral approach is extended to the post yield regime. To examine the path independency, the J* integral option is added to the finite element code. Numerical results for the J and J* integral formulations are given for a three point bending specimen loaded beyond the yield point

  1. Closed crack growth monitoring using nonlinear ultrasonic imaging method

    International Nuclear Information System (INIS)

    It was necessary to clarify closing mechanism of closed fatigue crack and evaluate such in high precision so as to ensure reliability of nuclear reactor and airplane. Three dimensional crack growth monitoring of closed crack depth distribution in the length direction and change in open and closed region within a crack with crack extension was conducted for closed fatigue crack created at compact tension specimen made of aluminium alloy A 7075 using such developed methods of subharmonic phased array for crack evaluation (SPACE), imaging method for closed cracks using nonlinear response of elastic waves at subharmonic frequency, and also load difference phased array (LPDA), nonlinear ultrasonic imaging method for closed cracks using subtraction of responses at different external loads. Results showed closed region within a crack was different in surface and inside and also open and closed region changed with crack extension in the three-dimensional way. (T. Tanaka)

  2. 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.

  3. 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)

  4. Investigations for designing catalytic recombiners

    International Nuclear Information System (INIS)

    In case of a severe accident in pressurised water reactors (PWR) a high amount of hydrogen up to about 20,000 m3 might be generated and released into the containments. The mixture consisting of hydrogen and oxygen may either burn or detonate, if ignited. In case of detonation the generated shock wave may endanger the components of the plant or the plant itself. Consequently, effective removal of hydrogen is required. The fact that hydrogen and oxygen react exo-thermally on catalytically acting surfaces already at low temperatures generating steam and heat is made use of in catalytic recombiners. They consist of substrates coated with catalyst (mainly platinum or palladium) which are arranged inside a casing. Being passively acting measures, recombiners do not need any additional energy supply. Experimental investigations on catalytic hydrogen recombination are conducted at FZJ (Forschungszentrum Juelich) using three test facilities. The results yield insight in the development potential of contemporary recombiner systems as well as of innovative systems. Detailed investigations on a recombiner section show strong temperature gradients over the surface of a catalytically coated sample. Dependent on the flow velocity, ignition temperature may be reached at the leading edge already at an inlet hydrogen concentration of about 5 vol.-%. The thermal strain of the substrate leads to considerable detachment of catalyst particles probably causing unintended ignition of the flammable mixture. Temperature peaks can be prevented effectively by leaving the first part of the plate uncoated. In order to avoid overheating of the catalyst elements of a recombiner even at high hydrogen concentrations a modular system of porous substrates is proposed. The metallic substrates are coated with platinum at low catalyst densities thus limiting the activity of the single specimen. A modular arrangement of these elements provides high recombination rates over a large hydrogen concentration

  5. 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.

  6. TEM observations of crack tip: cavity interactions

    International Nuclear Information System (INIS)

    Crack tip-cavity interactions have been studied by performing room temperature deformation experiments in a transmission electron microscope on ion-irradiated type 316 stainless steel with small helium containing cavities. Slip dislocations emitted from a crack tip cut, sheared, and thereby elongated cavities without a volume enlargement. As the crack tip approached, a cavity volume enlargement occurred. Instead of the cavities continuing to enlarge until they touch, the walls between the cavities fractured. Fracture surface dimples do not correlate in size or density with these enlarged cavities

  7. Mitigation strategies for autogenous shrinkage cracking

    DEFF Research Database (Denmark)

    Bentz, Dale P.; Jensen, Ole Mejlhede

    2004-01-01

    , the fundamental parameters contributing to the autogenous shrinkage and resultant early-age cracking of concrete are presented. Basic characteristics of the cement paste that contribute to or control the autogenous shrinkage response include the surface tension of the pore solution, the geometry of...... problem of early-age cracking due to autogenous shrinkage. Mitigation strategies discussed in this paper include: the addition of shrinkage-reducing admixtures more commonly used to control drying shrinkage, control of the cement particle size distribution, modification of the mineralogical composition of...... the field, it should be possible to minimize cracking due to autogenous shrinkage via some combination of the presented approaches....

  8. Crack Growth Properties of Sealing Glasses

    Science.gov (United States)

    Salem, Jonathan A.; Tandon, R.

    2008-01-01

    The crack growth properties of several sealing glasses were measured using constant stress rate testing in 2% and 95% RH (relative humidity). Crack growth parameters measured in high humidity are systematically smaller (n and B) than those measured in low humidity, and velocities for dry environments are approx. 100x lower than for wet environments. The crack velocity is very sensitivity to small changes in RH at low RH. Confidence intervals on parameters that were estimated from propagation of errors were comparable to those from Monte Carlo simulation.

  9. 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

  10. 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.

  11. 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.

  12. Numerical Study of Corrosion Crack Opening

    DEFF Research Database (Denmark)

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

    2008-01-01

    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......To determine the reliability of reinforced concrete structures based on visual inspection of corroding cracks on the surfaces of structures is of great interest. In the present study, models for the deterioration of reinforced concrete structures are presented with special emphasis on a model for...

  13. 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...... remeshing at several stages of the plastic deformation, with studies of the effect of overloads or compressive underloads. Recent published analyses for the first two cycles have shown folding of the crack surface in compression, leading to something that looks like striations. The influence of mesh...... 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....

  14. An electrochemical kinetics approach to the crack propagation at stress corrosion cracking of filmed metals

    International Nuclear Information System (INIS)

    An electrochemical model for crack propagation in film-covered metals, based on the film- rupture concept in stress corrosion cracking (SCC) of metals and quantitative electrochemical kinetics considerations, is presented and discussed. Using a general expression relating the rate of crack propagation with the electrochemical parameters of metal-environment systems, it is shown that the crack propagation rate depends on the rate constant of the metal dissolution reaction at the film-free crack tip, the ratio between the rate constants of the cathodic and metal dissolution reactions at the outer metal surface as well as on the reversible potentials of the cathodic, metal dissolution and film-forming reactions involved. It is also shown that the model can be applied for calculating the rate of crack propagation and explaining the differences in SCC behaviour of various metal-environment systems as well as for defining electrochemical conditions favourable for SCC. (Original)

  15. Catalytic denitrification control process and system for combustion flue gases

    International Nuclear Information System (INIS)

    This patent describes a process for controlling the catalytic dentrification of flue gases by ammonia addition to the flue gas. It comprises withdrawing from a combustion process a flue gas stream containing at least about 20 volume parts NOx per million of flue gas, and controllably adding ammonia gas to the flue gas stream; passing the flue gas and ammonia mixture through a catalytic dentrification unit containing a dentrification catalyst material and reducing the NOx concentration in the flue gas; obtaining a control signal based on process parameter signals including the volume flow rate of the flue gas, and determining the quantity of ammonia initially added to the flue gas so that it is less than the amount theoretically required to reduce all of the NOx in the flue gas; obtaining a trim signal based on comparing the NOx concentration measured in the flue gas downstream of the catalytic dentrification unit and a desired NOx concentration; and providing additional ammonia injection based on the trim signal by adjusting the ammonia addition flow rate as needed to provide the desired reduced NOx concentration being emitted to the atmosphere and to avoid excess ammonia injection and system oscillation

  16. 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  |

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

    Czech Academy of Sciences Publication Activity Database

    Kruml, Tomáš; Hutař, Pavel; Náhlík, Luboš; Seitl, Stanislav; Polák, Jaroslav

    2011-01-01

    Roč. 412, 1 (2011), s. 7-12. ISSN 0022-3115 R&D Projects: GA ČR GA106/09/1954; GA ČR GA101/09/0867 Institutional research plan: CEZ:AV0Z20410507 Keywords : ferritic-martensitic steel * long crack growth * small crack growth * crack closure Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.052, year: 2011

  18. Crack initiation and crack growth at the inner nozzle corner surface under thermal shock loading

    International Nuclear Information System (INIS)

    This paper reported about preliminary experimental work for estimating crack initiation loading cycles on ferritic and austenitic materials and crack growth rates. The maximum crack growth rates under operating conditions and with a high content of oxygen in the pressurized water (700 ppM) is comparable with the ASME-curve water within a δK range to 40 MN.m-3/2

  19. CRACK2. Modelling calcium carbonate deposition from bicarbonate solutions in cracks in concrete

    OpenAIRE

    Brodersen, Knud Erik

    2003-01-01

    The numerical CRACK2 model simulates precipitation of calcite from calcium bicarbonate solution (e.g. groundwater) passing through cracks in concrete or other cementitious materials. A summary of experimental work is followed by a detailed description ofthe model. Hydroxyl ions are transported 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. Thec...

  20. Cracking the code of change.

    Science.gov (United States)

    Beer, M; Nohria, N

    2000-01-01

    Today's fast-paced economy demands that businesses change or die. But few companies manage corporate transformations as well as they would like. The brutal fact is that about 70% of all change initiatives fail. In this article, authors Michael Beer and Nitin Nohria describe two archetypes--or theories--of corporate transformation that may help executives crack the code of change. Theory E is change based on economic value: shareholder value is the only legitimate measure of success, and change often involves heavy use of economic incentives, layoffs, downsizing, and restructuring. Theory O is change based on organizational capability: the goal is to build and strengthen corporate culture. Most companies focus purely on one theory or the other, or haphazardly use a mix of both, the authors say. Combining E and O is directionally correct, they contend, but it requires a careful, conscious integration plan. Beer and Nohria present the examples of two companies, Scott Paper and Champion International, that used a purely E or purely O strategy to create change--and met with limited levels of success. They contrast those corporate transformations with that of UK-based retailer ASDA, which has successfully embraced the paradox between the opposing theories of change and integrated E and O. The lesson from ASDA? To thrive and adapt in the new economy, companies must make sure the E and O theories of business change are in sync at their own organizations. PMID:11183975