Selective catalytic reduction (SCR) NOx control for small natural gas-fired prime movers

International Nuclear Information System (INIS)

Shareef, G.S.; Stone, D.K.; Ferry, K.R.; Johnson, K.L.; Locke, K.S.

1992-01-01

The application of selective catalytic reduction (SCR) to small natural gas-fired prime movers at cogeneration facilities and compressor stations could possibly increase due to regulatory forces to limit NO x from such sources. The natural gas industry is presently without a current database with which to evaluate the cost and operating characteristics of SCR under the conditions anticipated for small prime movers. This paper presents the results from a two-phase study undertaken to document SCR applications with emphasis on SCR system performance and costs. The database of small natural gas-fired prime mover SCR experience, focusing on prime mover characterization, SCR system performance, and SCR system costs will be described. Result from analysis of performance and cost data will be discussed, including analytical tools developed to project SCR system performance and costs

Process identification of the SCR system of coal-fired power plant for de-NOx based on historical operation data.

Science.gov (United States)

Li, Jian; Shi, Raoqiao; Xu, Chuanlong; Wang, Shimin

2018-05-08

The selective catalytic reduction (SCR) system, as one principal flue gas treatment method employed for the NO x emission control of the coal-fired power plant, is nonlinear and time-varying with great inertia and large time delay. It is difficult for the present SCR control system to achieve satisfactory performance with the traditional feedback and feedforward control strategies. Although some improved control strategies, such as the Smith predictor control and the model predictive control, have been proposed for this issue, a well-matched identification model is essentially required to realize a superior control of the SCR system. Industrial field experiment is an alternative way to identify the SCR system model in the coal-fired power plant. But it undesirably disturbs the operation system and is costly in time and manpower. In this paper, a process identification model of the SCR system is proposed and developed by applying the asymptotic method to the sufficiently excited data, selected from the original historical operation database of a 350 MW coal-fired power plant according to the condition number of the Fisher information matrix. Numerical simulations are carried out based on the practical historical operation data to evaluate the performance of the proposed model. Results show that the proposed model can efficiently achieve the process identification of the SCR system.

Mercury Oxidation over Selective Catalytic Reduction (SCR) Catalysts - Ph.d. thesis Karin Madsen

DEFF Research Database (Denmark)

Madsen, Karin

The vanadium-based SCR catalyst used for NOx-control promotes the oxidation of elemental mercury Hg0 to Hg2+ in flue gases from coal-fired power plants. Hg2+ is water soluble and can effectively be captured in a wet scrubber. This means that the combination of an SCR with a wet FGD can offer an e...

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials expecting diesel-auto emission regulation

International Nuclear Information System (INIS)

Komatsu, Tamikuni; Tomokuni, Keizou; Yamada, Issaku

2006-01-01

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials, which does not rely on the conventional NOx-absorption-reduction-catalysts, is presented for the purpose of de-NOx of diesel-auto emissions. The established catalysts basically consist of mesoporous silica or metal-substituted mesoporous silicates for supports and platinum for active species, which is operated under lean- and rich-conditions. The new catalysts are very active at 150-200 o C and free from difficult problems of SOx-deactivation and hydrothermal ageing of the NOx-absorption-reduction catalyst. (author)

On the Effect of Preparation Methods of PdCe-MOR Catalysts as NOx CH4-SCR System for Natural Gas Vehicles Application

Directory of Open Access Journals (Sweden)

Acácio Nobre Mendes

2015-10-01

Full Text Available In the present work, the effect of several parameters involved in the preparation of PdCe-HMOR catalysts active for NOx selective catalytic reduction with methane (NOx CH4-SCR was studied. Results show that the catalytic performance of Pd-HMOR is better when palladium is introduced by ion-exchange, namely at room temperature. It was also shown that Pd loading does not influence the formation of cerium species, namely surface Ce4+ (CeO2 species and CeO2 species in interaction with Pd. However, when Ce is introduced before Pd, more surface CeO2 species are stabilized in the support and less CeO2 become in interaction with Pd, which results in a worse NOx CH4-SCR catalytic performance.

A particle filter for ammonia coverage ratio and input simultaneous estimations in Diesel-engine SCR system.

Science.gov (United States)

Sun, Kangfeng; Ji, Fenzhu; Yan, Xiaoyu; Jiang, Kai; Yang, Shichun

2018-01-01

As NOx emissions legislation for Diesel-engines is becoming more stringent than ever before, an aftertreatment system has been widely used in many countries. Specifically, to reduce the NOx emissions, a selective catalytic reduction(SCR) system has become one of the most promising techniques for Diesel-engine vehicle applications. In the SCR system, input ammonia concentration and ammonia coverage ratio are regarded as essential states in the control-oriental model. Currently, an ammonia sensor placed before the SCR Can is a good strategy for the input ammonia concentration value. However, physical sensor would increase the SCR system cost and the ammonia coverage ratio information cannot be directly measured by physical sensor. Aiming to tackle this problem, an observer based on particle filter(PF) is investigated to estimate the input ammonia concentration and ammonia coverage ratio. Simulation results through the experimentally-validated full vehicle simulator cX-Emission show that the performance of observer based on PF is outstanding, and the estimation error is very small.

ULTRA LOW NOx INTEGRATED SYSTEM FOR NOx EMISSION CONTROL FROM COAL-FIRED BOILERS

Energy Technology Data Exchange (ETDEWEB)

Galen H. Richards; Charles Q. Maney; Richard W. Borio; Robert D. Lewis

2002-12-30

ALSTOM Power Inc.'s Power Plant Laboratories, working in concert with ALSTOM Power's Performance Projects Group, has teamed with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to conduct a comprehensive study to develop/evaluate low-cost, efficient NOx control technologies for retrofit to pulverized coal fired utility boilers. The objective of this project was to develop retrofit NOx control technology to achieve less than 0.15 lb/MMBtu NOx (for bituminous coals) and 0.10 lb/MMBtu NOx (for subbituminous coals) from existing pulverized coal fired utility boilers at a cost which is at least 25% less than SCR technology. Efficient control of NOx is seen as an important, enabling step in keeping coal as a viable part of the national energy mix in this century, and beyond. Presently 57% of U.S. electrical generation is coal based, and the Energy Information Agency projects that coal will maintain a lead in U.S. power generation over all other fuel sources for decades (EIA 1998 Energy Forecast). Yet, coal-based power is being strongly challenged by society's ever-increasing desire for an improved environment and the resultant improvement in health and safety. The needs of the electric-utility industry are to improve environmental performance, while simultaneously improving overall plant economics. This means that emissions control technology is needed with very low capital and operating costs. This project has responded to the industry's need for low NOx emissions by evaluating ideas that can be adapted to present pulverized coal fired systems, be they conventional or low NOx firing systems. The TFS 2000{trademark} firing system has been the ALSTOM Power Inc. commercial offering producing the lowest NOx emission levels. In this project, the TFS 2000{trademark} firing system served as a basis for comparison to other low NOx systems evaluated and was the foundation upon which refinements were made to further

Alternative SILP-SCR Catalysts based on Guanidinium Chromates

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Riisager, Anders; Ståhl, Kenny

There is an increasing global concern about human caused emissions of pollutants like sulfur and nitrogen oxides to the atmosphere leading to, e.g. smog and acid rain damaging to the human health and the environment. Selective catalytic reduction (SCR) of NOx with ammonia as reductant is the most...... duct. There is therefore a demand for alkali-resistant SCR catalysts more flexible regarding temperature of operation and position in the duct. Supported ionic liquid phase (SILP) catalysts with 1,1,3,3-Tetramethylguanidinium (TMGH+) and a chromium oxide anion supported on anatase have exhibited...

Cost and Fuel Efficient SCR-only Solution for post-2010 HD Emission Standards

NARCIS (Netherlands)

Cloudt, R.P.M.; Willems, F.P.T.; Heijden, van der P.

2009-01-01

A promising SCR-only solution is presented to meetpost-2010 NOx emission targets for heavy dutyapplications. The proposed concept is based on anengine from a EURO IV SCR application, which isconsidered optimal with respect to fuel economy andcosts. The addition of advanced SCR after

NOx Emission in Iron and Steel Production: A Review of Control Measures for Safe and Eco-Friendly Environment

Directory of Open Access Journals (Sweden)

U. A. Mukhtar

2017-12-01

Full Text Available Iron and steel manufacturing involved preparation of raw materials through processes such as sintering, pelletizing and coke making. During these processes, pollutants such as Sulphur (iv oxides (SO2 Carbon II oxides (CO, Nitrogen oxides (NOX, Volatile organic compounds (VOC and Particulate matter (PM etc. are emitted. The present work is aimed at describing some mitigation technologies of controlling emissions in iron and steel production. The processes involved in the production of iron and steel using Blast Furnace (BF and Basic Oxygen Furnace (BOF has been described. The mitigation technologies of controlling emissions were analyzed and discussed with environmental impacts based on the economical and technical factors. In this work, the data presented is based on existing reviews. The combination of low NOX burner (LNB and Selective catalytic reduction (SCR is capable of reducing emission for up to 90% and above. Emissions of other pollutants into the atmosphere as a result of ammonia slip, formation of acids and other gases are harmful to the environment and causes damage to the SCR systems. Installation and operation cost are the major impacts of the SCR technology in the process of iron and steel production.

Selective Catalytic Reduction (SCR) for mobile application - heavy duty diesel; Selektive Katalytische Reduktion (SCR) fuer die mobile Anwendung - LKW

Energy Technology Data Exchange (ETDEWEB)

Huennekes, E.; Neubauer, T. [Engelhard Technologies GmbH, Hannover (Germany); Roth, S.A.; Patchett, J.A. [Engelhard Corp., R and D, Iselin, NJ (United States)

2006-07-01

Different system configurations of particulate and NOx control via selective catalytic reduction (SCR) were discussed. Advantages and disadvantages were described and the final choice of the optimum system will strongly depend on the application, the market (US, EU) and the system costs. Especially when considering low temperature NOx control, the optimum adjustment of the NO{sub 2}/NO{sub x} ratio in front of an SCR system plays an important role. When generating NO2 over an oxidation catalyst, the resulting NO{sub 2}/NO{sub x} ratio strongly depends on temperature and space velocity. Steady state data show an optimum NO{sub 2}/NO{sub x} ratio between 35 and 60% at temperatures about 240 C. Three DOC systems in front of an SCR system were investigated with the purpose to generate high, low and optimum NO{sub 2}/NO{sub x} ratios. The fast SCR reaction at 1:1 NO: NO2 with NH{sub 3} is the preferred reaction pathway until either NO or NO{sub 2} are consumed. The benefit of an optimum designed DOC system can be seen in the transient response after a sudden increase in urea dosing. The time for the optimum designed system to reach maximum NO{sub x} conversion is much shorter compared with systems having excess NO or NO{sub 2} Ammonia oxidation catalysts (AMOX) are effective means in controlling ammonia from SCR systems. To be effective, AMOX must have selectivity to nitrogen over N{sub 2}O and NO{sub x}. (orig.)

Surface Species and Metal Oxidation State during H2-Assisted NH3-SCR of NOx over Alumina-Supported Silver and Indium

Directory of Open Access Journals (Sweden)

Linda Ström

2018-01-01

Full Text Available Alumina-supported silver and indium catalysts are investigated for the hydrogen-assisted selective catalytic reduction (SCR of NOx with ammonia. Particularly, we focus on the active phase of the catalyst and the formation of surface species, as a function of the gas environment. Diffuse reflectance ultraviolet-visible (UV-vis spectroscopy was used to follow the oxidation state of the silver and indium phases, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS was used to elucidate the formation of surface species during SCR conditions. In addition, the NOx reduction efficiency of the materials was evaluated using H2-assisted NH3-SCR. The DRIFTS results show that the Ag/Al2O3 sample forms NO-containing surface species during SCR conditions to a higher extent compared to the In/Al2O3 sample. The silver sample also appears to be more reduced by H2 than the indium sample, as revealed by UV-vis spectroscopic experiments. Addition of H2, however, may promote the formation of highly dispersed In2O3 clusters, which previously have been suggested to be important for the SCR reaction. The affinity to adsorb NH3 is confirmed by both temperature programmed desorption (NH3-TPD and in situ DRIFTS to be higher for the In/Al2O3 sample compared to Ag/Al2O3. The strong adsorption of NH3 may inhibit (self-poison the NH3 activation, thereby hindering further reaction over this catalyst, which is also shown by the lower SCR activity compared to Ag/Al2O3.

Experimental research of technology activating catalysts for SCR DeNOx in boiler

Science.gov (United States)

Zeng, Xi; Yang, Zhengde; Li, Yan; Chen, Donglin

2018-01-01

In order to improve activity of the catalysts used in SCR DeNOx system of flue gas, a series of catalysts activated by different activating liquids under varied conditions in boiler directly were conducted. Then these catalysts were characterized by SEM, FT-IR and BET technology. And NO conversions of the activated catalysts were studied and compared with that of inactivated catalyst. The above experiment shows that NO conversion of the activated catalyst can be up to 99%, which 30% higher than that of inactivated catalyst, so activity of catalysts were improved greatly. Furthermore, optimal activating liquid labeled L2 and effective technology parameters were gained in the experiment.

Cost and fuel efficient SCR-only solution for post-2010 HD emission standards

NARCIS (Netherlands)

Cloudt, R.P.M.; Willems, F.P.T.; Heijden, P.V.A.M. van der

2009-01-01

A promising SCR-only solution is presented to meet post-2010 NOx emission targets for heavy duty applications. The proposed concept is based on an engine from a EURO IV SCR application, which is considered optimal with respect to fuel economy and costs. The addition of advanced SCR after treatment

Experimental Assessment of NOx Emissions from 73 Euro 6 Diesel Passenger Cars.

Science.gov (United States)

Yang, Liuhanzi; Franco, Vicente; Mock, Peter; Kolke, Reinhard; Zhang, Shaojun; Wu, Ye; German, John

2015-12-15

Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selective catalytic reduction (SCR). Seventy-three Euro 6 diesel passenger cars (8 EGR only, 40 LNT, and 25 SCR) were tested on a chassis dynamometer over both the European type-approval cycle (NEDC, cold engine start) and the more realistic Worldwide harmonized light-duty test cycle (WLTC version 2.0, hot start) between 2012 and 2015. Most vehicles met the legislative limit of 0.08 g/km of NOx over NEDC (average emission factors by technology: EGR-only 0.07 g/km, LNT 0.04 g/km, and SCR 0.05 g/km), but the average emission factors rose dramatically over WLTC (EGR-only 0.17 g/km, LNT 0.21 g/km, and SCR 0.13 g/km). Five LNT-equipped vehicles exhibited very poor performance over the WLTC, emitting 7-15 times the regulated limit. These results illustrate how diesel NOx emissions are not properly controlled under the current, NEDC-based homologation framework. The upcoming real-driving emissions (RDE) regulation, which mandates an additional on-road emissions test for EU type approvals, could be a step in the right direction to address this problem.

Special requirements for the fluid mechanical design of hard coal-fired SCR retrofit units

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

The system design of high-dust SCR units for retrofits is a challenge that is to be mastered in order to meet the fluid mechanical requirements. Retrofitting power plants with NOx control technologies is a cost-intensive adventure that many utilities are undertaking. Except for a few recent new boiler installations, SCR installations must be considered as retrofit projects. In most cases the limitation of space on site entails unfavorable conditions that do not allow appropriate upstream conditions for SCR catalysts. To comply with the requirements of high performance DeNOx systems and to lower the investment costs for retrofit units, several technical solutions and concepts for the reactor layout, for NOx and dust distribution, for flow stabilization in diffusers, and advanced ammonia injection systems are explained in this paper. Balcke-Duerr offers customer-tailored solutions for flow optimization, which are evaluated by model studies. Physical flow and dust model tests in an appropriate scale provide flexibility to test various engineering concepts. The experience of Balcke-Duerr is based on continuous research and development activities over the last 25 years and more than 350 executed projects for gas flow optimization applications. The success of these installations is a direct result of the key decisions based on the improved fluid mechanical design and proper system integration. This paper also identifies the sensible design particularities and solutions that have two be considered in the fluid mechanical design of high-dust SCR retrofit units. This article demonstrates that the layout of SCR units must be carefully reviewed in order to meet the performance requirements and to avoid problems, i.e. wear, catalyst plugging and ammonia slip. 9 refs., 18 figs.

Influence of hydrogen treatment on SCR catalysts

DEFF Research Database (Denmark)

Due-Hansen, Johannes

stream, i.e. by in situ treatment of the Pt-catalyst by reductive H2-gas. However, the introduction of H2 gas in the gas stream could also affect other units in the tail pipe gas cleaning system. Of special interest in this study is the effect of hydrogen gas on the performance of the selective catalytic...... reduction (SCR) process, i.e. the catalytic removal of NOx from the flue gas. A series of experiments was conducted to reveal the impact on the NO SCR activity of a industrial DeNOX catalyst (3%V2O5-7%WO3/TiO2) by treatment of H2. Standard conditions were treatment of the SCR catalyst for 60 min with three...... different concentrations of H2 (0-2%) in a 8% O2/N2 mixture, where the SCR activity was measured before and after the hydrogen treatment. The results show that the activity of the SCR catalyst is only negligible affected during exposure to the H2/O2 gas and in all cases it returned reversibly to the initial...

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Marc Cremer; Kevin Davis; Martin Denison; Adel Sarofim; Connie Senior; Hong-Shig Shim; Dave Swenson; Bob Hurt; Eric Suuberg; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker

2006-06-30

This is the Final Report for DOE Cooperative Agreement No: DE-FC26-00NT40753. The goal of the project was to develop cost-effective analysis tools and techniques for demonstrating and evaluating low-NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) provided co-funding for this program. This project included research on: (1) In furnace NOx control; (2) Impacts of combustion modifications on boiler operation; (3) Selective Catalytic Reduction (SCR) catalyst testing and (4) Ammonia adsorption/removal on fly ash. Important accomplishments were achieved in all aspects of the project. Rich Reagent Injection (RRI), an in-furnace NOx reduction strategy based on injecting urea or anhydrous ammonia into fuel rich regions in the lower furnace, was evaluated for cyclone-barrel and PC fired utility boilers. Field tests successfully demonstrated the ability of the RRI process to significantly reduce NOx emissions from a staged cyclone-fired furnace operating with overfire air. The field tests also verified the accuracy of the Computational Fluid Dynamic (CFD) modeling used to develop the RRI design and highlighted the importance of using CFD modeling to properly locate and configure the reagent injectors within the furnace. Low NOx firing conditions can adversely impact boiler operation due to increased waterwall wastage (corrosion) and increased soot production. A corrosion monitoring system that uses electrochemical noise (ECN) corrosion probes to monitor, on a real-time basis, high temperature corrosion events within the boiler was evaluated. Field tests were successfully conducted at two plants. The Ohio Coal Development Office provided financial assistance to perform the field tests. To investigate soot behavior, an advanced model to predict soot production and destruction was implemented into an existing reacting CFD modeling tool. Comparisons between experimental data collected

Commercial introduction of the Advanced NOxTECH system

Energy Technology Data Exchange (ETDEWEB)

Sudduth, B.C. [NOxTECH, Inc., Irvine, CA (United States)

1997-12-31

NOxTECH is BACT for diesel electric generators. Emissions of NO{sub x} are reduced 95% or more with substantial concurrent reductions in CO, particulates, and ROG`s. No engine modifications or other exhaust aftertreatments can remove all criteria pollutants as effectively as NOxTECH. The NOxTECH system reliably maintains NH{sub 3} slip below 2 ppm. Unlike other emissions controls, NOxTECH does not generate hazardous by-products. The Advanced NOxTECH system reduces the size, weight, and cost for BACT emissions reductions. Based on the operation of a 150 kW prototype, NOxTECH, Inc. is quoting commercial units for diesel electric generators. Advanced NOxTECH equipment costs about half as much as SCR systems, and NO{sub x} reduction can exceed 95% with guarantees for emissions compliance.

Fe-BEA Zeolite Catalysts for NH3-SCR of NOx

DEFF Research Database (Denmark)

Frey, Anne Mette; Mert, Selcuk; Due-Hansen, Johannes

2009-01-01

Iron-containing zeolites are known to be promising catalysts for the NH3-SCR reaction. Here, we will investigate the catalytic activity of iron-based BEA catalysts, which was found to exhibit improved activities compared to previously described iron-containing zeolite catalysts, such as ZSM-5...... and ZSM-12. Series of Fe-BEA zeolite catalysts were prepared using a range of different preparation methods. Furthermore, we found that an iron concentration around 3 wt% on BEA showed a small optimum in SCR activity compared to the other iron loadings studied....

Neural networks prove effective at NOx reduction

Energy Technology Data Exchange (ETDEWEB)

Radl, B.J. [Pegasus Technologies, Mentor, OH (USA)

2000-05-01

The availability of low cost computer hardware and software is opening up possibilities for the use of artificial intelligence concepts, notably neural networks, in power plant control applications, delivering lower costs, greater efficiencies and reduced emissions. One example of a neural network system is the NeuSIGHT combustion optimisation system, developed by Pegasus Technologies, a subsidiary of KFx Inc. It can help reduce NOx emissions, improve heat rate and enable either deferral or elimination of capital expenditures. on other NOx control technologies, such as low NOx burners, SNCR and SCR. This paper illustrates these benefits using three recent case studies. 4 figs.

LPV gain-scheduled control of SCR aftertreatment systems

Science.gov (United States)

Meisami-Azad, Mona; Mohammadpour, Javad; Grigoriadis, Karolos M.; Harold, Michael P.; Franchek, Matthew A.

2012-01-01

Hydrocarbons, carbon monoxide and some of other polluting emissions produced by diesel engines are usually lower than those produced by gasoline engines. While great strides have been made in the exhaust aftertreatment of vehicular pollutants, the elimination of nitrogen oxide (NO x ) from diesel vehicles is still a challenge. The primary reason is that diesel combustion is a fuel-lean process, and hence there is significant unreacted oxygen in the exhaust. Selective catalytic reduction (SCR) is a well-developed technology for power plants and has been recently employed for reducing NO x emissions from automotive sources and in particular, heavy-duty diesel engines. In this article, we develop a linear parameter-varying (LPV) feedforward/feedback control design method for the SCR aftertreatment system to decrease NO x emissions while keeping ammonia slippage to a desired low level downstream the catalyst. The performance of the closed-loop system obtained from the interconnection of the SCR system and the output feedback LPV control strategy is then compared with other control design methods including sliding mode, and observer-based static state-feedback parameter-varying control. To reduce the computational complexity involved in the control design process, the number of LPV parameters in the developed quasi-LPV (qLPV) model is reduced by applying the principal component analysis technique. An LPV feedback/feedforward controller is then designed for the qLPV model with reduced number of scheduling parameters. The designed full-order controller is further simplified to a first-order transfer function with a parameter-varying gain and pole. Finally, simulation results using both a low-order model and a high-fidelity and high-order model of SCR reactions in GT-POWER interfaced with MATLAB/SIMULINK illustrate the high NO x conversion efficiency of the closed-loop SCR system using the proposed parameter-varying control law.

Experimental study on the particulate matter and nitrogenous compounds from diesel engine retrofitted with DOC+CDPF+SCR

Science.gov (United States)

Zhang, Yunhua; Lou, Diming; Tan, Piqiang; Hu, Zhiyuan

2018-03-01

The increasingly stringent emission regulations will mandate the retrofit of after-treatment devices for in-use diesel vehicles, in order to reduce their substantial particulate matter and nitrogen oxides (NOX) emissions. In this paper, a combination of DOC (diesel oxidation catalyst), CDPF (catalytic diesel particulate filter) and SCR (selective catalytic reduction) retrofit for a heavy-duty diesel engine was employed to perform experiment on the engine test bench to evaluate the effects on the particulate matter emissions including particle number (PN), particle mass (PM), particle size distributions and nitrogenous compounds emissions including NOX, nitrogen dioxide (NO2)/NOX, nitrous oxide (N2O) and ammonia (NH3) slip. In addition, the urea injection was also of our concern. The results showed that the DOC+CDPF+SCR retrofit almost had no adverse effect on the engine power and fuel consumption. Under the test loads, the upstream DOC and CDPF reduced the PN and PM by an average of 91.6% and 90.9%, respectively. While the downstream SCR brought about an average decrease of 85% NOX. Both PM and NOX emission factors based on this retrofit were lower than China-Ⅳ limits (ESC), and even lower than China-Ⅴ limits (ESC) at medium and high loads. The DOC and CDPF changed the particle size distributions, leading to the increase in the proportion of accumulation mode particles and the decrease in the percentage of nuclear mode particles. This indicates that the effect of DOC and CDPF on nuclear mode particles was better than that of accumulation mode ones. The upstream DOC could increase the NO2/NOX ratio to 40%, higher NO2/NOX ratio improved the efficiency of CDPF and SCR. Besides, the N2O emission increased by an average of 2.58 times after the retrofit and NH3 slip occurred with the average of 26.7 ppm. The rate of urea injection was roughly equal to 8% of the fuel consumption rate. The DOC+CDPF+SCR retrofit was proved a feasible and effective measurement in terms

Development of Optimal Catalyst Designs and Operating Strategies for Lean NOx Reduction in Coupled LNT-SCR Systems

Energy Technology Data Exchange (ETDEWEB)

Harold, Michael [Univ. of Houston, TX (United States); Crocker, Mark [Univ. of Kentucky, Lexington, KY (United States); Balakotaiah, Vemuri [Univ. of Houston, TX (United States); Luss, Dan [Univ. of Houston, TX (United States); Choi, Jae-Soon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dearth, Mark [Ford Motor Company, Dearborn, MI (United States); McCabe, Bob [Ford Motor Company, Dearborn, MI (United States); Theis, Joe [Ford Motor Company, Dearborn, MI (United States)

2013-09-30

Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO₂) commonly referred to as NO_x, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NO_x} is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NO_x in the presence of excess O₂. Catalytic abatement measures that are effective for gasoline-fueled engines such as the precious metal containing three-way catalytic converter (TWC) cannot be used to treat O₂-laden exhaust containing NO_x. Two catalytic technologies that have emerged as effective for NO_x abatement are NO_x storage and reduction (NSR) and selective catalytic reduction (SCR). NSR is similar to TWC but requires much larger quantities of expensive precious metals and sophisticated periodic switching operation, while SCR requires an on-board source of ammonia which serves as the chemical reductant of the NO_x. The fact that NSR produces ammonia as a byproduct while SCR requires ammonia to work has led to interest in combining the two together to avoid the need for the cumbersome ammonia generation system. In this project a comprehensive study was carried out of the fundamental aspects and application feasibility of combined NSR/SCR. The project team, which included university, industry, and national lab researchers, investigated the kinetics and mechanistic features of the underlying chemistry in the lean NOx trap (LNT) wherein NSR was carried out, with particular focus on identifying the operating conditions such as temperature and catalytic properties which lead to the production of ammonia in the LNT. The performance features of SCR on both model and commercial catalysts focused on the synergy between the LNT and SCR converters in terms of utilizing the upstream-generated ammonia and

In-use NOx emissions from model year 2010 and 2011 heavy-duty diesel engines equipped with aftertreatment devices.

Science.gov (United States)

Misra, Chandan; Collins, John F; Herner, Jorn D; Sax, Todd; Krishnamurthy, Mohan; Sobieralski, Wayne; Burntizki, Mark; Chernich, Don

2013-07-16

The California Air Resources Board (ARB) undertook this study to characterize the in-use emissions of model year (MY) 2010 or newer diesel engines. Emissions from four trucks: one equipped with an exhaust gas recirculation (EGR) and three equipped with EGR and a selective catalytic reduction (SCR) device were measured on two different routes with three different payloads using a portable emissions measurement system (PEMS) in the Sacramento area. Results indicated that brake-specific NOx emissions for the truck equipped only with an EGR were independent of the driving conditions. Results also showed that for typical highway driving conditions, the SCR technology is proving to be effective in controlling NOx emissions. However, under operations where the SCR's do not reach minimum operating temperature, like cold starts and some low load/slow speed driving conditions, NOx emissions are still elevated. The study indicated that strategies used to maintain exhaust temperature above a certain threshold, which are used in some of the newer SCRs, have the potential to control NOx emissions during certain low-load/slow speed driving conditions.

Analysis and study on the performance variation of SCR DeNOx catalyst of Coal-Fired Boilers

International Nuclear Information System (INIS)

Jianxing, Ren; Fangqin, Li; Jiang, Wu; Qingrong, Liu; Yongwen, Yang; Zhongzhu, Qiu

2010-01-01

Nitrogen oxides (NO x ) are one kind of harmful substances from the burning process of fossil fuel and air at high temperature. NO x emissions cause serious pollution on atmospheric environment. In this paper, coal-fired utility boilers were chosen as the object, NO x formation mechanism and control were studied, and SCR deNO x technology was used to control NO x emissions from coal-fired boilers. Analyzed the relationship between deNO x efficiency and characteristics of SCR DeNO x catalyst. Through analysis, affecting SCR DeNO x catalyst failure factors, change law of catalytic properties and technical measures to extend the service life of the catalyst were gotten. (author)

The development and application of SCR denitrification technology in power plant

Science.gov (United States)

Wu, Junnan

2017-12-01

In recent decades, the emission of the nitrogen oxides (NOX) has been increasing with the years of the thermal power plant. The environment pollution caused by the emission of quantities of nitrogen oxides became more and more serious, so people now put more emphasis on the control of the emission of the nitrogen oxides. Especially, our country and the society are paying much more attention to the environment protection and the environment problems cannot be neglected. In this paper, we introduced the related research background of the technology of SCR denitrification which was as the symbol of the technology of the catalytic denitrification and discussed the reaction principles of the SCR denitrification and frequently used catalysts, the process of the technology, and the configuration. In the end, we pointed the way of the future research of the technology of the SCR denitrification.

The effect of the gas composition on hydrogen-assisted NH3-SCR over Ag/Al2O3

DEFF Research Database (Denmark)

Tamm, Stefanie; Fogel, Sebastian; Gabrielsson, Pär

2013-01-01

In addition to high activity in hydrocarbon-SCR, Ag/Al2O3 catalysts show excellent activity for NOx reduction for H2-assisted NH3-SCR already at 200°C. Here, we study the influence of different gas compositions on the activity of a pre-sulfated 6wt% Ag/Al2O3 catalyst for NOx reduction, and oxidat...

Demonstration of SCR technology for the control of NOx emissions from high-sulfur coal-fired utility boilers

Energy Technology Data Exchange (ETDEWEB)

Hinton, W.S. [W.S. Hinton and Associates, Cantonment, FL (United States); Maxwell, J.D.; Healy, E.C.; Hardman, R.R. [Southern Company Services, Inc., Birmingham, AL (United States); Baldwin, A.L. [Dept. of Energy, Pittsburgh, PA (United States)

1997-12-31

This paper describes the completed Innovative Clean Coal Technology project which demonstrated SCR technology for reduction of flue gas NO{sub x} emissions from a utility boiler burning US high-sulfur coal. The project was sponsored by the US Department of Energy, managed and co-funded by Southern Company Services, Inc. on behalf of the Southern Company, and also co-funded by the Electric Power Research Institute and Ontario Hydro. The project was located at Gulf Power Company`s Plant Crist Unit 5 (a 75 MW tangentially-fired boiler burning US coals that had a sulfur content ranging from 2.5--2.9%), near Pensacola, Florida. The test program was conducted for approximately two years to evaluate catalyst deactivation and other SCR operational effects. The SCR test facility had nine reactors: three 2.5 MW (5,000 scfm), and operated on low-dust flue gas. The reactors operated in parallel with commercially available SCR catalysts obtained from suppliers throughout the world. Long-term performance testing began in July 1993 and was completed in July 1995. A brief test facility description and the results of the project are presented in this paper.

EVALUATION OF MERCURY EMISSIONS FROM COAL-FIRED FACILITIES WITH SCR AND FGD SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; S.C. Tseng; J. E. Locke

2004-10-31

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP) - wet flue gas desulfurization (FGD) combination or a spray dyer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on Hg speciation and the efficacy of different FGD technologies for Hg capture. This document, the second in a series of topical reports, describes the results and analysis of mercury sampling performed on a 330 MW unit burning a bituminous coal containing 1.0% sulfur. The unit is equipped with a SCR system for NOx control and a spray dryer absorber for SO{sub 2} control followed by a baghouse unit for particulate emissions control. Four sampling tests were performed in March 2003. Flue gas mercury speciation and concentrations were determined at the SCR inlet, air heater outlet (ESP inlet), and at the stack (FGD outlet) using the Ontario Hydro method. Process stream samples for a mercury balance were collected to coincide with the flue gas measurements. Due to mechanical problems with the boiler feed water pumps, the actual gross output was between 195 and 221 MW during the tests. The results showed that the SCR/air heater combination oxidized nearly 95% of the elemental mercury. Mercury removal, on a

Effect of selective catalytic reduction (SCR) on fine particle emission from two coal-fired power plants in China

Science.gov (United States)

Li, Zhen; Jiang, Jingkun; Ma, Zizhen; Wang, Shuxiao; Duan, Lei

2015-11-01

Nitrogen oxides (NOx) emission abatement of coal-fired power plants (CFPPs) requires large-scaled installation of selective catalytic reduction (SCR), which would reduce secondary fine particulate matter (PM2.5) (by reducing nitrate aerosol) in the atmosphere. However, our field measurement of two CFPPs equipped with SCR indicates a significant increase of SO42- and NH4+ emission in primary PM2.5, due to catalytic enhancement of SO2 oxidation to SO3 and introducing of NH3 as reducing agent. The subsequent formation of (NH4)2SO4 or NH4HSO4 aerosol is commonly concentrated in sub-micrometer particulate matter (PM1) with a bimodal pattern. The measurement at the inlet of stack also showed doubled primary PM2.5 emission by SCR operation. This effect should therefore be considered when updating emission inventory of CFPPs. By rough estimation, the enhanced primary PM2.5 emission from CFPPs by SCR operation would offset 12% of the ambient PM2.5 concentration reduction in cities as the benefit of national NOx emission abatement, which should draw attention of policy-makers for air pollution control.

Advanced CIDI Emission Control System Development

Energy Technology Data Exchange (ETDEWEB)

Lambert, Christine

2006-05-31

Ford Motor Company, with ExxonMobil and FEV, participated in the Department of Energy's (DOE) Ultra-Clean Transportation Fuels Program with the goal to develop an innovative emission control system for light-duty diesel vehicles. The focus on diesel engine emissions was a direct result of the improved volumetric fuel economy (up to 50%) and lower CO2 emissions (up to 25%) over comparable gasoline engines shown in Europe. Selective Catalytic Reduction (SCR) with aqueous urea as the NOx reductant and a Catalyzed Diesel Particulate Filter (CDPF) were chosen as the primary emission control system components. The program expected to demonstrate more than 90% durable reduction in particulate matter (PM) and NOx emissions on a light-duty truck application, based on the FTP-75 drive cycle. Very low sulfur diesel fuel (<15 ppm-wt) enabled lower PM emissions, reduced fuel economy penalty due to the emission control system and improved long-term system durability. Significant progress was made toward a durable system to meet Tier 2 Bin 5 emission standards on a 6000 lbs light-duty truck. A 40% reduction in engine-out NOx emissions was achieved with a mid-size prototype diesel engine through engine recalibration and increased exhaust gas recirculation. Use of a rapid warm-up strategy and urea SCR provided over 90% further NOx reduction while the CDPF reduced tailpipe PM to gasoline vehicle levels. Development work was conducted to separately improve urea SCR and CDPF system durability, as well as improved oxidation catalyst function. Exhaust gas NOx and ammonia sensors were also developed further. While the final emission control system did not meet Tier 2 Bin 5 NOx after 120k mi of aging on the dynamometer, it did meet the standards for HC, NMOG, and PM, and an improved SCR catalyst was shown to have potential to meet the NOx standard, assuming the DOC durability could be improved further. Models of DOC and SCR function were developed to guide the study of several key

INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

Science.gov (United States)

The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

Reburning technology - a means to reduce NOx emissions

International Nuclear Information System (INIS)

Kremer, H.; Lorra, M.

1999-01-01

Nitrogen oxide emission control technologies can be classified as either combustion modifications to minimize the NO production or post-combustion flue gas treatment to reduce the NO concentration afterwards. The techniques for minimizing NOx Production includes the use of low-NOx burners, overfire air (staged combustion) and boiler combustion optimization. Procedures for flue gas treatment can be subdivided into selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR). The re burning process is a selective non-catalytic technology which is applicable to a wide variety of boilers and can be implemented within a relatively short period of time. The NOx reduction potential of this technique is in the range of 50 % up to 70 %. (author)

Alternative deNOx catalysts and technologies

DEFF Research Database (Denmark)

Due-Hansen, Johannes

The present thesis entitled Alternative deNOx Catalysts and technologies revolves around the topic of removal of nitrogen oxides. Nitrogen oxides, NOx, are unwanted byproducts formed during combustion (e.g. in engines or power plants). If emitted to the atmosphere, they are involved...... in the formation of acid rain and photochemical smog. Some basic concepts and reactions regarding the formation and removal of NOx are presented in chapter 1 and 2. Two approaches are undertaken in the present work to reduce the emission of NOx: by means of catalytic removal, and by NO absorption in ionic liquids....... The commercial catalyst used for the selective catalytic reduction (SCR) of nitrogen oxides exhibits high activity and selectivity towards N2. However, the vanadia-titania-based catalyst used is very sensitive to deactivation by alkali-species (primarily potassium), which are typically present in high amounts...

Study on Optimization Experiment of SCR Denitrification Technologies in a Coal-fired Power Plant

Science.gov (United States)

Zhang, Limeng; Dong, Xinguang; Hou, Fanjun; Liu, Ke; Che, Gang

2018-01-01

Optimization experiment of SCR denitrification technologies on a 300MW unit was conducted. Adjustment of ammonia injection quantity of corresponding AIG was conducted after measuring the SCR export NOx concentration field in 250MW load, the distribution uniformity of NOx volume fraction at the outlet of both reactor A and B was improved significantly, where the relative standard deviation of NOx reduced respectively from 29.83% to 13.01% and 24.54% to 9.26%, simultaneously, the amount of ammonia escape of A, B reactor decrease respectively by 24.76%, 19.45%. The results of optimization experiment show that, optimal adjustment can improve the NOx concentration distribution, reduce the amount of ammonia escape in a certain extent, and judge whether the catalytic activity of the regional catalyzer is in good condition. As to the area where catalyst is ineffective, the effect of optimization experiment is limited, the catalyzer should be the timely replacement, so as to better protect downstream equipment.

EVALUATION OF MERCURY EMISSIONS FROM COAL-FIRED FACILITIES WITH SCR AND FGD SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

J.A. Withum; S.C. Tseng; J.E. Locke

2005-11-01

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) and the Electric Power Research Institute (EPRI), is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP)--wet flue gas desulfurization (FGD) combination or a spray dryer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. This document, the seventh in a series of topical reports, describes the results and analysis of mercury sampling performed on a 1,300 MW unit burning a bituminous coal containing three percent sulfur. The unit was equipped with an ESP and a limestone-based wet FGD to control particulate and SO2 emissions, respectively. At the time of sampling an SCR was not installed on this unit. Four sampling tests were performed in September 2003. Flue gas mercury speciation and concentrations were determined at the ESP outlet (FGD inlet), and at the stack (FGD outlet) using the Ontario Hydro method. Process stream samples for a mercury balance were collected to coincide with the flue gas measurements. The results show that the FGD inlet flue gas oxidized:elemental mercury ratio was roughly 2:1, with 66% oxidized mercury and 34% elemental mercury. Mercury removal, on a coal

Urea thermolysis and NOx reduction with and without SCR catalysts

International Nuclear Information System (INIS)

Fang, Howard L.; DaCosta, Herbert F.M.

2003-01-01

Urea-selective catalytic reduction (SCR) has been a leading contender for removal of nitrogen oxides (deNO x ) from diesel engine emissions. Despite its advantages, the SCR technology faces some critical detriments to its catalytic performance such as catalyst surface passivation (caused by deposit formation) and consequent stoichiometric imbalance of the urea consumption. Deposit formation deactivates catalytic performance by not only consuming part of the ammonia produced during urea decomposition but also degrading the structural and thermal properties of the catalyst surface. We have characterized the urea thermolysis with and without the urea-SCR catalyst using both spectroscopic (DRIFTS and Raman) and thermal techniques (thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC)) to identify the deposit components and their corresponding thermal properties. Urea thermolysis exhibits two decomposition stages, involving ammonia generation and consumption, respectively. The decomposition after the second stage leads to the product of melamine complexes, (HNC=NH) x (HNCO) y , that hinder catalytic performance. The presence of catalyst accompanied with a good spray of the urea solution helps to eliminate the second stage. In this work, kinetics of the direct reduction of NO x by urea is determined and the possibility of using additives to the urea solution in order to rejuvenate the catalyst surface and improve its performance will be discussed

New developments of high dust-SCR technology in the cement industry results of pilot tests in Solnhofen and development state of a full scale SCR unit; Nouveaux developpements de la technologie SCR ''High Dust'' dans l'industrie du ciment - resultats de tests pilotes a Solnhoffen et etat de developpement d'une unite pilote a l'echelle

Energy Technology Data Exchange (ETDEWEB)

Samant, G. [Lurgi Energie und Entsorgung GmbH, Frankfurt (Germany); Sauter, G. [Soinhofer Portland Zementwerke AG, Solnhofen (Germany); Haug, N. [Agence Federale de l' Environnement, Berlin (Germany)

2001-07-01

The production of clinker in the cement industry involve the formation of nitrous oxides, and the emission limits are becoming more stringent from year to year. The added up total NOx emissions from the European cement industry amounts at present approx. 450.000 Mg/year. As such it is high time for the decision to develop and implement a technology to reduce NOx-emissions. At present SCR technology which is implemented in the glass industry, waste incineration and power plants seems to be the best economical and ecological solution for cement industry. In the period time from 1997 to the end of 1999 pilot plant test work was carried out by the companies 'Solnhofer Portland Zementwerke AG' and 'mg Engineering Lurgi' in the cement plant in Solnhofen. The results of pilot plan test work show that NOx reduction rates above 90% with NH{sub 3} slip less then 5 vppm can be achieved. The results of the test work with different type of catalysts are discussed. Based on the results of the test work a suitable SCR-process for cement industry is developed. At present a High-Dust-SCR demonstration plant at 'Solnhofer Portland Zementwerke AG' with the help of German Federal Environmental Agency, UBA-Berlin, is under commissioning and going on stream. (authors)

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Temi Linjewile; Connie Senior; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding

2004-06-30

This is the sixteenth Quarterly Technical Report for DOE Cooperative Agreement No: DEFC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. During an unplanned outage, damage occurred to the electrochemical noise corrosion probes installed at the AEP Gavin plant; testing is expected to resume in August. The KEMCOP corrosion coupons were not affected by the unplanned outage; the coupons were removed and sent for analysis. BYU conducted a series of tests before the ISSR lab was relocated. Ammonia adsorption experiments provided clear evidence of the types of acidic sites present on catalyst surfaces. Data collected this quarter indicate that surface sulfation decreases Lewis acid site concentrations for all catalysts thus far studied, confirming that catalytic activity under commercial coal-based SCR conditions occurs primarily on Br{o}nsted acid sites and would be susceptible to basic impurities such as alkali and alkaline earth oxides, chlorides, and sulfates. SCR activity tests based on MS analysis showed that increasing sulfation generally increases NO reduction activity for both 0% and 1% vanadia catalysts. During this quarter, the slipstream reactor at Rockport operated for 720 hours on flue gas. Catalyst exposure time reached 4500 hours since installation. The reactor is out of service at the Rockport plant and plans are being made to move it to the Gadsden Plant. At Gadsden, modifications have begun in preparation for installation of the slipstream reactor next quarter.

The NOx Budget. Market-based control of tropospheric ozone in the northeastern United States

International Nuclear Information System (INIS)

Farrell, Alex; Carter, Robert; Raufer, Roger

1999-01-01

The NOx Budget is a marketable emissions allowance system currently being adopted by states in the Northeastern US to reduce tropospheric ozone concentrations to healthful levels in a cost-effective manner. Oxides of nitrogen (NOx) are currently regulated within the existing Command and Control (CAC) framework. The introduction of a market-based approach will further reduce emissions, but will not resolve all regulatory uncertainties. These implementation concerns are identified and discussed. Cost savings and emissions reductions patterns which will arise under several different scenarios are determined through the use of a dynamic, relaxed mixed-integer linear programming model of the NOx allowance market. Like other market-based pollution control programs, the NOx Budget is found to be more efficient than CAC options. Restrictions on the market designed to address perceived flaws are found to be expensive but ineffectual

Hydrogen Peroxide Enhances Removal of NOx from Flue Gases

Science.gov (United States)

Collins, Michelle M.

2005-01-01

Pilot scale experiments have demonstrated a method of reducing the amounts of oxides of nitrogen (NOx) emitted by industrial boilers and powerplant combustors that involves (1) injection of H2O2 into flue gases and (2) treatment of the flue gases by caustic wet scrubbing like that commonly used to remove SO2 from combustion flue gases. Heretofore, the method most commonly used for removing NOx from flue gases has been selective catalytic reduction (SCR), in which the costs of both installation and operation are very high. After further development, the present method may prove to be an economically attractive alternative to SCR.

Cyclone Boiler Field Testing of Advanced Layered NOx Control Technology in Sioux Unit 1

Energy Technology Data Exchange (ETDEWEB)

Marc A. Cremer; Bradley R. Adams

2006-06-30

A four week testing program was completed during this project to assess the ability of the combination of deep staging, Rich Reagent Injection (RRI), and Selective Non-Catalytic Reduction (SNCR) to reduce NOx emissions below 0.15 lb/MBtu in a cyclone fired boiler. The host site for the tests was AmerenUE's Sioux Unit 1, a 500 MW cyclone fired boiler located near St. Louis, MO. Reaction Engineering International (REI) led the project team including AmerenUE, FuelTech Inc., and the Electric Power Research Institute (EPRI). This layered approach to NOx reduction is termed the Advanced Layered Technology Approach (ALTA). Installed RRI and SNCR port locations were guided by computational fluid dynamics (CFD) based modeling conducted by REI. During the parametric testing, NOx emissions of 0.12 lb/MBtu were achieved consistently from overfire air (OFA)-only baseline NOx emissions of 0.25 lb/MBtu or less, when firing the typical 80/20 fuel blend of Powder River Basin (PRB) and Illinois No.6 coals. From OFA-only baseline levels of 0.20 lb/MBtu, NOx emissions of 0.12 lb/MBtu were also achieved, but at significantly reduced urea flow rates. Under the deeply staged conditions that were tested, RRI performance was observed to degrade as higher blends of Illinois No.6 were used. NOx emissions achieved with ALTA while firing a 60/40 blend were approximately 0.15 lb/MBtu. NOx emissions while firing 100% Illinois No.6 were approximately 0.165 lb/MBtu. Based on the performance results of these tests, economics analyses of the application of ALTA to a nominal 500 MW cyclone unit show that the levelized cost to achieve 0.15 lb/MBtu is well below 75% of the cost of a state of the art SCR.

Reactivity of Surface Nitrates in H2-Assisted SCR of NOx Over Ag/Al2O3 Catalyst

DEFF Research Database (Denmark)

Sadokhina, N. A.; Doronkin, Dmitry E.; Baeva, G. N.

2013-01-01

The role of nitrate ad-species in H2-assisted SCR over Ag/Al2O3 was compared in NH3-SCR and n-C6H14-SCR processes. It was found that nitrates could be reduced by NH3 or n-C6H14 at similar rates with H2 co-feeding which indicates a common rate-limiting step. However, contributions of surface nitrate...... reduction to the overall NH3-SCR or n-C6H14-SCR are different as revealed by comparing the rates of nitrate reduction with the rates of steady-state processes. The rate of the steady-state n-C6H14-SCR is virtually identical to the rate of surface nitrate reduction suggesting a significant contribution...... of the surface nitrates reduction to the overall n-C6H14-SCR process. On the other hand, the steady-state rate of NH3-SCR is by ~15 times higher, which indicates that the reduction of surface nitrates plays a marginal role in the overall NH3-SCR....

Congressionally Directed Project for Passive NOx Removal Catalysts Research

Energy Technology Data Exchange (ETDEWEB)

Schneider, William [Univ. of Notre Dame, IN (United States)

2014-12-29

The Recipient proposes to produce new scientific and technical knowledge and tools to enable the discovery and deployment of highly effective materials for the selective catalytic reduction (SCR) of nitrogen oxides (NOx) from lean combustion exhaust. A second goal is to demonstrate a closely coupled experimental and computational approach to heterogeneous catalysis research. These goals will be met through the completion of four primary technical objectives: First, an in-depth kinetic analysis will be performed on two prominent classes of NOx SCR catalysts, Fe- and Cu-exchanged beta and ZSM-5 zeolites, over a wide range of catalyst formulation and under identical, high conversion conditions as a function of gas phase composition. Second, the nanoscale structure and adsorption chemistry of these high temperature (HT) and low temperature (LT) catalysts will be determined using in situ and operando spectroscopy under the same reaction conditions. Third, first-principles molecular simulations will be used to model the metal-zeolite active sites, their adsorption chemistry, and key steps in catalytic function. Fourth, this information will be integrated into chemically detailed mechanistic and kinetic descriptions and models of the operation of these well- defined NOx SCR catalysts under practically relevant reaction conditions. The new knowledge and models that derive from this work will be published in the scientific literature.

Model predictive control of a lean-burn gasoline engine coupled with a passive selective catalytic reduction system

Energy Technology Data Exchange (ETDEWEB)

Chen, Pingen [Tennessee Technological University (TTU); Lin, Qinghua [Tennessee Technological University (TTU); Prikhodko, Vitaly Y. [ORNL

2017-10-01

Lean-burn gasoline engines have demonstrated 10–20% engine efficiency gain over stoichiometric engines and are widely considered as a promising technology for meeting the 54.5 miles-per-gallon (mpg) Corporate Average Fuel Economy standard by 2025. Nevertheless, NOx emissions control for lean-burn gasoline for meeting the stringent EPA Tier 3 emission standards has been one of the main challenges towards the commercialization of highly-efficient lean-burn gasoline engines in the United States. Passive selective catalytic reduction (SCR) systems, which consist of a three-way catalyst and SCR, have demonstrated great potentials of effectively reducing NOx emissions for lean gasoline engines but may cause significant fuel penalty due to ammonia generation via rich engine combustion. The purpose of this study is to develop a model-predictive control (MPC) scheme for a lean-burn gasoline engine coupled with a passive SCR system to minimize the fuel penalty associated with passive SCR operation while satisfying stringent NOx and NH3 emissions requirements. Simulation results demonstrate that the MPC-based control can reduce the fuel penalty by 47.7% in a simulated US06 cycle and 32.0% in a simulated UDDS cycle, compared to the baseline control, while achieving over 96% deNOx efficiency and less than 15 ppm tailpipe ammonia slip. The proposed MPC control can potentially enable high engine efficiency gain for highly-efficient lean-burn gasoline engine while meeting the stringent EPA Tier 3 emission standards.

Low NOx combustion and SCR flow field optimization in a low volatile coal fired boiler.

Science.gov (United States)

Liu, Xing; Tan, Houzhang; Wang, Yibin; Yang, Fuxin; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

2018-08-15

Low NO x burner redesign and deep air staging have been carried out to optimize the poor ignition and reduce the NO x emissions in a low volatile coal fired 330 MW e boiler. Residual swirling flow in the tangentially-fired furnace caused flue gas velocity deviations at furnace exit, leading to flow field unevenness in the SCR (selective catalytic reduction) system and poor denitrification efficiency. Numerical simulations on the velocity field in the SCR system were carried out to determine the optimal flow deflector arrangement to improve flow field uniformity of SCR system. Full-scale experiment was performed to investigate the effect of low NO x combustion and SCR flow field optimization. Compared with the results before the optimization, the NO x emissions at furnace exit decreased from 550 to 650 mg/Nm³ to 330-430 mg/Nm³. The sample standard deviation of the NO x emissions at the outlet section of SCR decreased from 34.8 mg/Nm³ to 7.8 mg/Nm³. The consumption of liquid ammonia reduced from 150 to 200 kg/h to 100-150 kg/h after optimization. Copyright © 2018. Published by Elsevier Ltd.

Enhanced Combustion Low NOx Pulverized Coal Burner

Energy Technology Data Exchange (ETDEWEB)

David Towle; Richard Donais; Todd Hellewell; Robert Lewis; Robert Schrecengost

2007-06-30

For more than two decades, Alstom Power Inc. (Alstom) has developed a range of low cost, infurnace technologies for NOx emissions control for the domestic U.S. pulverized coal fired boiler market. This includes Alstom's internally developed TFS 2000{trademark} firing system, and various enhancements to it developed in concert with the U.S. Department of Energy. As of the date of this report, more than 270 units representing approximately 80,000 MWe of domestic coal fired capacity have been retrofit with Alstom low NOx technology. Best of class emissions range from 0.18 lb/MMBtu for bituminous coal to 0.10 lb/MMBtu for subbituminous coal, with typical levels at 0.24 lb/MMBtu and 0.13 lb/MMBtu, respectively. Despite these gains, NOx emissions limits in the U.S. continue to ratchet down for new and existing boiler equipment. On March 10, 2005, the Environmental Protection Agency (EPA) announced the Clean Air Interstate Rule (CAIR). CAIR requires 25 Eastern states to reduce NOx emissions from the power generation sector by 1.7 million tons in 2009 and 2.0 million tons by 2015. Low cost solutions to meet such regulations, and in particular those that can avoid the need for a costly selective catalytic reduction system (SCR), provide a strong incentive to continue to improve low NOx firing system technology to meet current and anticipated NOx control regulations. The overall objective of the work is to develop an enhanced combustion, low NOx pulverized coal burner, which, when integrated with Alstom's state-of-the-art, globally air staged low NOx firing systems will provide a means to achieve: Less than 0.15 lb/MMBtu NOx emissions when firing a high volatile Eastern or Western bituminous coal, Less than 0.10 lb/MMBtu NOx emissions when firing a subbituminous coal, NOx reduction costs at least 25% lower than the costs of an SCR, Validation of the NOx control technology developed through large (15 MWt) pilot scale demonstration, and Documentation required for

Innovative clean coal technology (ICCT): demonstration of selective catalytic reduction (SCR) technology for the control of nitrogen oxide (NOx) emission from high-sulfur, coal-fired boilers - economic evaluation of commercial-scale SCR applications for utility boilers

International Nuclear Information System (INIS)

Healy, E.C.; Maxwell, J.D.; Hinton, W.S.

1996-09-01

This report presents the results of an economic evaluation produced as part of the Innovative Clean Coal Technology project, which demonstrated selective catalytic reduction (SCR) technology for reduction of NO x emissions from utility boilers burning U.S. high-sulfur coal. The document includes a commercial-scale capital and O ampersand M cost evaluation of SCR technology applied to a new facility, coal-fired boiler utilizing high-sulfur U.S. coal. The base case presented herein determines the total capital requirement, fixed and variable operating costs, and levelized costs for a new 250-MW pulverized coal utility boiler operating with a 60-percent NO x removal. Sensitivity evaluations are included to demonstrate the variation in cost due to changes in process variables and assumptions. This report also presents the results of a study completed by SCS to determine the cost and technical feasibility of retrofitting SCR technology to selected coal-fired generating units within the Southern electric system

Evaluation of Mercury Emissions from Coal-Fired Facilities with SCR and FGD Systems

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; J. E. Locke

2006-02-01

, respectively. Unit 1 is similar to Unit 2, except that Unit 1 has no SCR for NOx control. Four sampling tests were performed on both units in January 2005; flue gas mercury speciation and concentrations were determined at the economizer outlet, air heater outlet (ESP inlet), ESP outlet (FGD inlet), and at the stack (FGD outlet) using the Ontario Hydro method. Process samples for material balances were collected with the flue gas measurements. The results show that the SCR increased the oxidation of the mercury at the air heater outlet. At the exit of the air heater, a greater percentage of the mercury was in the oxidized and particulate forms on the unit equipped with an SCR compared to the unit without an SCR (97.4% vs 91%). This higher level of oxidation resulted in higher mercury removals in the scrubber. Total mercury removal averaged 97% on the unit with the SCR, and 87% on the unit without the SCR. The average mercury mass balance closure was 84% on Unit 1 and 103% on Unit 2.

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Temi Linjewile; Connie Senior; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding

2003-06-30

This is the twelfth Quarterly Technical Report for DOE Cooperative Agreement No: DE-FC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. This program contains multiple tasks and good progress is being made on all fronts. During this quarter, a new effort was begun on the development of a corrosion management system for minimizing the impacts of low NOx combustion systems on waterwalls; a kickoff meeting was held at the host site, AEP's Gavin Plant, and work commenced on fabrication of the probes. FTIR experiments for SCR catalyst sulfation were finished at BYU and indicated no vanadium/vanadyl sulfate formation at reactor conditions. Improvements on the mass-spectrometer system at BYU have been made and work on the steady state reactor system shakedown neared completion. The slipstream reactor continued to operate at AEP's Rockport plant; at the end of the quarter, the catalysts had been exposed to flue gas for about 1000 hours. Some operational problems were addressed that enable the reactor to run without excessive downtime by the end of the quarter.

An Improved Flexible Solar Thermal Energy Integration Process for Enhancing the Coal-Based Energy Efficiency and NOx Removal Effectiveness in Coal-Fired Power Plants under Different Load Conditions

Directory of Open Access Journals (Sweden)

Yu Han

2017-09-01

Full Text Available An improved flexible solar-aided power generation system (SAPG for enhancing both selective catalytic reduction (SCR de-NOx efficiency and coal-based energy efficiency of coal-fired power plants is proposed. In the proposed concept, the solar energy injection point is changed for different power plant loads, bringing about different benefits for coal-fired power generation. For partial/low load, solar energy is beneficially used to increase the flue gas temperature to guarantee the SCR de-NOx effectiveness as well as increase the boiler energy input by reheating the combustion air. For high power load, solar energy is used for saving steam bleeds from turbines by heating the feed water. A case study for a typical 1000 MW coal-fired power plant using the proposed concept has been performed and the results showed that, the SCR de-NOx efficiency of proposed SAPG could increase by 3.1% and 7.9% under medium load and low load conditions, respectively, as compared with the reference plant. The standard coal consumption rate of the proposed SAPG could decrease by 2.68 g/kWh, 4.05 g/kWh and 6.31 g/kWh for high, medium and low loads, respectively, with 0.040 USD/kWh of solar generated electricity cost. The proposed concept opens up a novel solar energy integration pattern in coal-fired power plants to improve the pollutant removal effectiveness and decrease the coal consumption of the power plant.

Multiphase catalysts for selective reduction of NOx with hydrocarbons

International Nuclear Information System (INIS)

Maisuls, S.E.

2000-01-01

Among the existing proposed solutions to reduce emission of NOx there is a promising alternative, the so-called (HC-SCR) selective catalytic reduction of NOx using hydrocarbons as reductant. This thesis is part of a worldwide effort devoted to gain knowledge on the selective catalytic reduction of NOx with hydrocarbons with the final goal to contribute to the development of suitable catalysts for the above mentioned process. Chapter 2 describes the details of the experimental set-up and of the analytical methods employed. Among the catalyst for HC-SCR, Co-based catalyst are known to be active and selective, thus, a study on a series of Co-based catalysts, supported on zeolites, was undertaken and the results are presented in Chapter 3. Correlation between catalytic characteristics and kinetic results are employed to understand the working catalyst and this is used as a basis for catalyst optimization. With the intention to prepare a multi-functional catalyst that will preserve the desired characteristics of the individual components, minimizing their negative aspects, catalysts based on Co-Pt, supported on ZSM-5, were investigated. In Chapter 4 the results of this study are discussed. A bimetallic Co-Pt/ZSM-5 catalysts with low Pt contents (0.1 wt %) showed a synergistic effect by combining high stability and activity of Pt catalysts with the high N2 selectivity of Co catalysts. Furthermore, it was found to be sulfur- and water-tolerant. Its positive qualities brought us to study the mechanism that takes place over this catalyst during HC-SCR. The results of an in-situ i.r mechanistic study over this catalyst is reported in Chapter 5. From the results presented in Chapter 5 a mechanism operating over the Co-Pt/ZSM-5 catalyst is proposed. The modification of Co catalyst with Pt improved the catalysts. However, further improvement was found to be hindered by high selectivity to N2O. Since Rh catalysts are generally less selective to N2O, the modification of Co

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Connie Senior Darren Shino; Dave Swenson; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding

2004-09-30

This is the seventeenth Quarterly Technical Report for DOE Cooperative Agreement No: DEFC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. The SCR slipstream reactor was assembled and installed at Plant Gadsden this quarter. Safety equipment for ammonia had not been installed at the end of the quarter, but will be installed at the beginning of next quarter. The reactor will be started up next quarter. Four ECN corrosion probes were reinstalled at Gavin and collected corrosion data for approximately one month. Two additional probes were installed and removed after about 30 hours for future profilometry analysis. Preliminary analysis of the ECN probes, the KEMA coupons and the CFD modeling results all agree with the ultrasonic tube test measurements gathered by AEP personnel.

DeNOx Abatement over Sonically Prepared Iron-Substituted Y, USY and MFI Zeolite Catalysts in Lean Exhaust Gas Conditions

Science.gov (United States)

Stachurska, Patrycja; Kuterasiński, Łukasz; Dziedzicka, Anna; Górecka, Sylwia; Chmielarz, Lucjan; Łojewska, Joanna; Sitarz, Maciej

2018-01-01

Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C. PMID:29301370

Selective catalytic reduction of NOx and N{sub 2}O by NH{sub 3} over Fe-FER; Developpement d'un traitement catalytique combine des NOx et de N{sub 2}O par NH{sub 3} sur Fe-Fer

Energy Technology Data Exchange (ETDEWEB)

Kieger, St. [Grande Paroisse, 76 - Grand-Quevilly (France); Navascues, L.; Gry, Ph. [Grande Paroisse, 92 - Paris la Defense (France)

2001-07-01

The emission of nitrogen oxides from anthropogenic activities is a major environmental issue. N{sub 2}O is taking part to the global warming and depletion of the stratospheric ozone layer, and NOx to acid rains. At the Kyoto Conference in 1997, the European Union committed itself to reduce by 8% the release of greenhouse gases at the horizon 2010. The selective catalytic reduction (SCR) of NOx by NH{sub 3} is nowadays the main control technology for the emissions from nitric acid plant. Therefore, Grande Paroisse and IRMA have developed a new catalyst (Fe-FER) for the SCR of N{sub 2}O by NH{sub 3}. The catalyst was evaluated in a pilot plant and in the same operating conditions than a DeNOx catalyst. At a space velocity of 9000 to 12000 h{sup -1}, a decomposition of 50% of N{sub 2}O was achieved at 440 deg C. Moreover for the same decomposition level, the temperature could be shifted to 390 deg C by adding ammonia, and the complete reduction of NOx was also observed. This new catalyst is rather bi-functional. Also after months of using, the catalyst did not show major loss of activity nor mechanical strength. (authors)

Design and implementation of mixing chambers to improve thermal decomposition of urea for NOX abatement

KAUST Repository

Lee, Junggil

2012-10-01

Urea-selective catalytic reduction (SCR) has been reported as the most promising technique for adherence to NOX emissions regulations. In the urea-SCR process, NH3 is generated by urea thermal decomposition and hydrolysis and is then used as a reductant of NOX in the SCR catalyst. Therefore, improving the NOX conversion efficiency of urea-SCR requires enhancement of thermal decomposition upstream of the SCR catalyst. In the present work, two types of mixing chambers were designed and fabricated to improve urea thermal decomposition, and experiments with and without a mixing chamber were carried out to analyze thermal-decomposition characteristics of urea in the exhaust pipe with respect to inlet velocity (4-12μm/s) and temperature (350°C-500°C). Urea thermal decomposition is greatly enhanced at higher gas temperatures. At an inlet velocity of 6μm/s in the A-type mixing chamber, NH3 concentrations generated along the exhaust pipe were about 171% and 157% greater than those without the mixing chamber for inlet temperatures of 400°C and 500°C, respectively. In the case of the B-type mixing chamber, NH3 concentrations generated at inlet temperatures of 400°C and 500°C were about 147% and 179% greater than those without the mixing chamber, respectively. Note that the implementation of mixing chambers significantly enhanced conversion of urea to NH3 because it increased the residence time of urea in the exhaust pipe and improved mixing between urea and exhaust gas. © 2012, Mary Ann Liebert, Inc.

Radio-Frequency-Controlled Urea Dosing for NH₃-SCR Catalysts: NH₃ Storage Influence to Catalyst Performance under Transient Conditions.

Science.gov (United States)

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-11-28

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NO x emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH₃) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH₃ loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH₃ storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH₃ storage levels, and NH₃ target curves. It could be clearly demonstrated that the right NH₃ target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NO x conversion efficiency and without NH₃ slip.

Modeling the selective catalytic reduction of NOx by ammonia over a Vanadia-based catalyst from heavy duty diesel exhaust gases

International Nuclear Information System (INIS)

Yun, Byoung Kyu; Kim, Man Young

2013-01-01

A numerical simulation for prediction of NO X conversion over a commercial V 2 O 5 catalyst with NH 3 as a reductant was performed for a heavy duty diesel engine applications. The chemical behaviors of the SCR reactor are described by using the global NO X kinetics including standard, fast, and NH 3 oxidation reactions with the Langmuir–Hinshelwood (LH) mechanism incorporated into the commercial Boost code. After introducing mathematical models for the SCR reaction with specific reaction parameters, the effects of various parameters such as space velocities, the O 2 , H 2 O, NO 2 , and NH 3 concentrations on the NOx conversion are thoroughly studied and validated by comparing with the experimental data available in the literature. It is found that NO X conversion increases with decreasing space velocity, H 2 O concentration, and NH 3 /NO X ratio, and increasing O 2 concentration and NO 2 /NO X ratio. The study shows that not only is the present approach adopted is flexible in treating performance of the commercial V 2 O 5 based SCR catalyst, it is also accurate and efficient for the prediction of NO X conversion in diesel exhaust environments. - Highlights: ► To find the reaction parameters for LH mechanism over a commercial V2O5 catalyst. ► To investigate the effects of various parameters on the SCR NO X conversion. ► To present benchmark solutions on SCR behavior with diesel exhaust environments.

COST-EFFECTIVE CONTROL OF NOx WITH INTEGRATED ULTRA LOW-NOx BURNERS AND SNCR

International Nuclear Information System (INIS)

Hamid Farzan

2001-01-01

Coal-fired electric utilities are facing a serious challenge with regards to curbing their NO(sub x) emissions. At issue are the NO(sub x) contributions to the acid rain, ground level ozone, and particulate matter formation. Substantial NO(sub x) control requirements could be imposed under the proposed Ozone Transport Rule, National Ambient Air Quality Standards, and New Source Performance Standards. McDermott Technology, Inc. (MTI), Babcock and Wilcox (B and W), and Fuel Tech are teaming to provide an integrated solution for NO(sub x) control. The system will be comprised of an ultra low-NO(sub x) pulverized coal (PC) burner technology plus a urea-based, selective non-catalytic reduction (SNCR) system. This system will be capable of meeting a target emission limit of 0.15 lb NO(sub x)/10(sup 6) Btu and target ammonia (NH3) slip level targeted below 5 ppmV for commercial units. Our approach combines the best available combustion and post-combustion NO(sub x) control technologies. More specifically, B and W's DRB-4Z TM ultra low-NO(sub x) PC burner technology will be combined with Fuel Tech's NO(sub x)OUT (SNCR) and NO(sub x)OUT Cascade (SNCR/SCR hybrid) systems and jointly evaluated and optimized in a state-of-the-art test facility at MTI. Although the NO(sub x)OUT Cascade (SNCR/SCR hybrid) system will not be tested directly in this program, its potential application for situations that require greater NO(sub x) reductions will be inferred from other measurements (i.e., SNCR NO(sub x) removal efficiency plus projected NO(sub x) reduction by the catalyst based on controlled ammonia slip). Our analysis shows that the integrated ultra low-NO(sub x) burner and SNCR system has the lowest cost when the burner emissions are 0.25 lb NO(sub x)/10(sup 6) Btu or less. At burner NO(sub x) emission level of 0.20 lb NO(sub x)/10(sup 6) Btu, the levelized cost per ton of NO(sub x) removed is 52% lower than the SCR cost

Evaluation of air jet erosion profiles in metal mesh supported SCR plate catalyst based on glass fiber concentrations

Science.gov (United States)

Rajath, S.; Nandakishora, Y.; Siddaraju, C.; Roy, Sukumar

2018-04-01

This paper explains the evaluation of erosion profiles in metal mesh supported SCR plate catalyst structures in which the glass fibers concentration in the catalyst material is considered as prime factor for erosion resistance and mechanical strength. The samples are prepared and tested at the specified and constant conditions like velocity as 30m/s, sand flow rate as 2g/min, average particle diameter 300 µm and all these samples were tested at different angles at impact preferably 15°,30°,45°,60°,75°,and 90° as per ASTM G76 standards. Say, if 5% glass fibers are present in catalyst material, then erosion resistance increases, but the density of glass fibers is very less because each glass fiber is approximately 20 microns in diameter and weight of individual is negligible. The composition in which 2% fiber is present has slightly higher erosion comparatively, but 3% glass fibers or more foreign inclusion like excessive binders can be eliminated that contributes much for the conversion of NOx. So 2% -3% glass fibers are preferred and optimized based on NOx conversion and erosion resistance property.

In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

Science.gov (United States)

Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian

2018-03-01

A series of ceria modified zirconium phosphate catalysts were synthesized for selective catalytic reduction of NO with ammonia (NH3-SCR). Over 98% NOx conversion and 98% N2 selectivity were obtained by the CeO2/ZrP catalyst with 20 wt.% CeO2 loading at 250-425 °C. The interaction between CeO2 and zirconium phosphate enhanced the redox abilities and surface acidities of the catalysts, resulting in the improvement of NH3-SCR activity. The in situ DRIFTS results indicated that the NH3-SCR reaction over the catalysts followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. The amide (sbnd NH2) groups and the NH4+ bonded to Brønsted acid sites were the important intermediates of Eley-Rideal mechanism.

Promotion effect of H2 on ethanol oxidation and NOx reduction with ethanol over Ag/Al2O3 catalyst.

Science.gov (United States)

Yu, Yunbo; Li, Yi; Zhang, Xiuli; Deng, Hua; He, Hong; Li, Yuyang

2015-01-06

The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol-SCR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol-SCR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing -NCO species again, leading to enhancement of ethanol-SCR over Ag/Al2O3 by H2. Using VUV-PIMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC-SCR over Ag/Al2O3.

Alternative alkali resistant deNOx catalysts

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes

2012-01-01

by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH3-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V2O5-WO3/TiO2 catalyst. After potassium poisoning (100......Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared......–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V2O5-WO3/TiO2 catalyst. Furthermore, Cu/MOR and Nano-V2O5/Sul-TiO2 catalysts showed 8–16 times higher SCR activities than the conventional even after high...

Near-Zero Emissions Oxy-Combustion Flue Gas Purification Task 2: SOx/Nox/Hg Removal for High Sulfur Coal

Energy Technology Data Exchange (ETDEWEB)

Nick Degenstein; Minish Shah; Doughlas Louie

2012-05-01

The goal of this project is to develop a near-zero emissions flue gas purification technology for existing PC (pulverized coal) power plants that are retrofitted with oxy-combustion technology. The objective of Task 2 of this project was to evaluate an alternative method of SOx, NOx and Hg removal from flue gas produced by burning high sulfur coal in oxy-combustion power plants. The goal of the program was not only to investigate a new method of flue gas purification but also to produce useful acid byproduct streams as an alternative to using a traditional FGD and SCR for flue gas processing. During the project two main constraints were identified that limit the ability of the process to achieve project goals. 1) Due to boiler island corrosion issues >60% of the sulfur must be removed in the boiler island with the use of an FGD. 2) A suitable method could not be found to remove NOx from the concentrated sulfuric acid product, which limits sale-ability of the acid, as well as the NOx removal efficiency of the process. Given the complexity and safety issues inherent in the cycle it is concluded that the acid product would not be directly saleable and, in this case, other flue gas purification schemes are better suited for SOx/NOx/Hg control when burning high sulfur coal, e.g. this project's Task 3 process or a traditional FGD and SCR.

Redox behaviour of vanadium during hydrogen-oxygen exposure of the V2O5-WO3/TiO2 SCR catalyst at 250 degrees C

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren B.; Mikolajska, Ewelina

2011-01-01

of H-2 (0-2%) in an 8% O-2/N-2 mixture, where the SCR activity was measured before and after the hydrogen treatment. The results show that the activity of the SCR catalyst is only negligibly affected during exposure to the H-2/O-2 gas and in all cases it returned reversibly to the initial NOx...... conversion rate after reexposure to the standard NH3-SCR gas. In situ electron paramagnetic resonance (EPR) and UV-vis spectroscopy at 250 degrees C suggest that a significant part of V4+ present during SCR conditions was oxidized to V5+ during exposure to 2% H-2 + 8% O-2. However, the distribution...

Impacts of Aging Emission Control Systems on In-Use Heavy-Duty Diesel Truck Emission Rates

Science.gov (United States)

Preble, C.; Cados, T.; Harley, R.; Kirchstetter, T.

2017-12-01

Heavy-duty diesel trucks are a major source of nitrogen oxides (NOx) and black carbon (BC) in urban environments, contributing to persistent ozone and particulate matter air quality problems. Recently, diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems have become standard equipment on new trucks. Particle filters can also be installed as a retrofit on older engines. Prior work has shown that exhaust filters and SCR systems effectively reduce BC and NOx emission rates by up to 90 and 80%, respectively (Preble et al., ES&T 2015). There is concern, however, that DPFs may promote the formation of ultrafine particles (UFP) and increase tailpipe emissions of nitrogen dioxide (NO2). Additionally, urea-based SCR systems for NOx control may form nitrous oxide (N2O), an important contributor to stratospheric ozone depletion. The effectiveness of these emission controls has been thoroughly evaluated in the laboratory, but the long-term durability of in-use systems and their impacts on co-emitted species have not been well characterized. To evaluate the in-use performance of DPF and SCR systems, pollutant emissions from thousands of diesel trucks were measured over several years at the Port of Oakland and the Caldecott Tunnel in the San Francisco Bay Area. Pollutants present in the exhaust plumes of individual trucks were measured at high time resolution (≥1 Hz) as trucks passed under a mobile lab stationed on an overpass. Fuel-based emission factors (g pollutant emitted per kg fuel burned) were calculated for individual trucks and linked via recorded license plates to vehicle attributes, including engine model year and installed emission control systems. Use of DPFs reduced the BC emission rate by up to 95% at both locations. SCR systems were more effective at reducing NOx emissions under the uphill, highway driving conditions at the Caldecott Tunnel. The emission rates of co-emitted species NO2, UFP, and N2O depended on driving

Effects of After-Treatment Control Technologies on Heavy-Duty Diesel Truck Emissions

Science.gov (United States)

Preble, C.; Dallmann, T. R.; Kreisberg, N. M.; Hering, S. V.; Harley, R.; Kirchstetter, T.

2015-12-01

Diesel engines are major emitters of nitrogen oxides (NOx) and the black carbon (BC) fraction of particulate matter (PM). Diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have recently become standard on new heavy-duty diesel trucks (HDDT). There is concern that DPFs may increase ultrafine particle (UFP) and total particle number (PN) emissions while reducing PM mass emissions. Also, the deliberate catalytic oxidation of engine-out NO to NO2 in continuously regenerating DPFs may lead to increased tailpipe emission of NO2 and near-roadway concentrations that exceed the 1-hr national ambient air quality standard. Increased NO2 emissions can also promote formation of ozone and secondary PM. We report results from ongoing on-road studies of HDDT emissions at the Port of Oakland and the Caldecott Tunnel in California's San Francisco Bay Area. Emission factors (g pollutant per kg diesel) were linked via recorded license plates to each truck's engine model year and installed emission controls. At both sites, DPF use significantly increased the NO2/NOx emission ratio. DPFs also significantly increased NO2 emissions when installed as retrofits on older trucks with higher baseline NOx emissions. While SCR systems on new trucks effectively reduce total NOx emissions and mitigate these undesirable DPF-related NO2 emissions, they also lead to significant emission of N2O, a potent greenhouse gas. When expressed on a CO2-equivalent basis, the N2O emissions increase offsets the fuel economy gain (i.e., the CO2 emission reduction) associated with SCR use. At the Port, average NOx, BC and PN emission factors from new trucks equipped with DPF and SCR were 69 ± 15%, 92 ± 32% and 66 ± 35% lower, respectively, than modern trucks without these emission controls. In contrast, at the Tunnel, PN emissions from older trucks retrofit with DPFs were ~2 times greater than modern trucks without DPFs. The difference

Urea-SCR technology for deNOx after treatment of diesel exhausts

CERN Document Server

Nova, Isabella

2014-01-01

Of intense interest both to academics and industry professionals, this groundbreaking book-length treatment of selective catalytic reduction of NOx using ammonia/urea includes papers by researchers at the leading edge of diesel exhaust abatement.

SOx-NOx-Rox Box{trademark} flue gas clean-up demonstration. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-09-01

Babcock and Wilcox`s (B and W) SOx-NOx-Rox Box{trademark} process effectively removes SOx, NOx and particulate (Rox) from flue gas generated from coal-fired boilers in a single unit operation, a high temperature baghouse. The SNRB technology utilizes dry sorbent injection upstream of the baghouse for removal of SOx and ammonia injection upstream of a zeolitic selective catalytic reduction (SCR) catalyst incorporated in the baghouse to reduce NOx emissions. Because the SOx and NOx removal processes require operation at elevated gas temperatures (800--900 F) for high removal efficiency, high-temperature fabric filter bags are used in the baghouse. The SNRB technology evolved from the bench and laboratory pilot scale to be successfully demonstrated at the 5-MWe field scale. This report represents the completion of Milestone M14 as specified in the Work Plan. B and W tested the SNRB pollution control system at a 5-MWe demonstration facility at Ohio Edison`s R.E. Burger Plant located near Shadyside, Ohio. The design and operation were influenced by the results from laboratory pilot testing at B and W`s Alliance Research Center. The intent was to demonstrate the commercial feasibility of the SNRB process. The SNRB facility treated a 30,000 ACFM flue gas slipstream from Boiler No. 8. Operation of the facility began in May 1992 and was completed in May 1993. About 2,300 hours of high-temperature operation were achieved. The main emissions control performance goals of: greater than 70% SO{sub 2} removal using a calcium-based sorbent; greater than 90% NOx removal with minimal ammonia slip; and particulate emissions in compliance with the New Source Performance Standards (NSPS) of 0.03 lb/million Btu were exceeded simultaneously in the demonstration program when the facility was operated at optimal conditions. Testing also showed significant reductions in emissions of some hazardous air pollutants.

Regenerative Snubber For GTO-Commutated SCR Inverter

Science.gov (United States)

Rippel, Wally E.; Edwards, Dean B.

1992-01-01

Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.

Combustion, performance, and selective catalytic reduction of NOx for a diesel engine operated with combined tri fuel (H_2, CH_4, and conventional diesel)

International Nuclear Information System (INIS)

Abu-Jrai, Ahmad M.; Al-Muhtaseb, Ala'a H.; Hasan, Ahmad O.

2017-01-01

In this study, the effect of tri fuel (ULSD, H_2, and CH_4) operation under real exhaust gas conditions with different gaseous fuel compositions on the combustion characteristics, engine emissions, and selective catalytic reduction (SCR) after treatment was examined at low, medium, and high engine loads. Pt/Al_2O_3-SCR reactor was used and operated at different exhaust gas temperatures. Results revealed that at low load, the two gaseous fuels (H_2 and CH_4) have the same trend on combustion proccess, where both reduce the in-cylinder pressure and rate of heat release. At the high engine load there was a considerable influence appeared as an increase of the premixed combustion phase and a significant decrease of the total combustion duration. In terms of emissions, it was observed that at high engine load, fuels with high CH_4 content tend to reduce NOx formation, whereas, fuels with high H_2 content tend to reduce PM formation, moreover, combustion of tri fuel with 50:50 fuel mixture resulted in lower BSFC compared to the other ratios and hence, the best engine efficiency. The hydrocarbon-SCR catalyst has shown satisfactory performance in NOx reduction under real diesel exhaust gas in a temperature window of 180–280 °C for all engine loads. - Highlights: • Effect of tri fuel (ULSD, H_2, CH_4) on combustion and engine emissions was examined. • Fuel with high CH_4 content (H50-M50 and H25-M75) tend to reduce NOx formation. • Fuel with high H_2 content (H75-M25 and H50-M50) tend to reduce PM formation. • Increasing the percentage of H_2 in the feed gas improved the NO_x reduction. • The hydrocarbon-SCR catalyst has shown satisfactory performance in NO_x reduction.

NOX EMISSION CONTROL OPTIONS FOR COAL-FIRED ELECTRIC UTILITY BOILERS

Science.gov (United States)

The paper reviews NOx control options for coal-fired electric utility boilers. (NOTE: Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, revision of the New Source Performance Standards (NSPS) for NOx emissions from utility sources, and Ozone Transpor...

NoxO1 Controls Proliferation of Colon Epithelial Cells

Directory of Open Access Journals (Sweden)

Franziska Moll

2018-05-01

Full Text Available AimReactive oxygen species (ROS produced by enzymes of the NADPH oxidase family serve as second messengers for cellular signaling. Processes such as differentiation and proliferation are regulated by NADPH oxidases. In the intestine, due to the exceedingly fast and constant renewal of the epithelium both processes have to be highly controlled and balanced. Nox1 is the major NADPH oxidase expressed in the gut, and its function is regulated by cytosolic subunits such as NoxO1. We hypothesize that the NoxO1-controlled activity of Nox1 contributes to a proper epithelial homeostasis and renewal in the gut.ResultsNoxO1 is highly expressed in the colon. Knockout of NoxO1 reduces the production of superoxide in colon crypts and is not subsidized by an elevated expression of its homolog p47phox. Knockout of NoxO1 increases the proliferative capacity and prevents apoptosis of colon epithelial cells. In mouse models of dextran sulfate sodium (DSS-induced colitis and azoxymethane/DSS induced colon cancer, NoxO1 has a protective role and may influence the population of natural killer cells.ConclusionNoxO1 affects colon epithelium homeostasis and prevents inflammation.

Research progress on catalytic denitrification technology in chemical industry

Science.gov (United States)

Jin, Yezhi

2017-12-01

In recent years, due to the rising emission of NOx annually, attention has been aroused widely by people on more and more severe environmental problems. This paper first discusses applying NOx removal and control technologies and relating chemical principles. Of many technologies, selective reduction reaction (SCR) is the most widely used. Catalysts, the concentration of NOx at the entrance of SCR catalytic reactor, reaction temperature, NH3/NOx mole ratio and NH3 slip rate analyzed later contributes to the removal efficiency of NOx. Finally, the processing and configuration of SCR de-NOx system are briefly introduced.

Closed loop engine control for regulating NOx emissions, using a two-dimensional fuel-air curve

Science.gov (United States)

Bourn, Gary D.; Smith, Jack A.; Gingrich, Jess W.

2007-01-30

An engine control strategy that ensures that NOx emissions from the engine will be maintained at an acceptable level. The control strategy is based on a two-dimensional fuel-air curve, in which air manifold pressure (AMP) is a function of fuel header pressure and engine speed. The control strategy provides for closed loop NOx adjustment to a base AMP value derived from the fuel-air curve.

Effect of the sol-gel conditions on the morphology and SCR performance of electrospun V-W-TiO2 catalysts

DEFF Research Database (Denmark)

Marani, Debora; Silva, Rafael Hubert; Dankeaw, Apiwat

2018-01-01

V-W-TiO2 catalysts are prepared as nanofibers for the removal of the NOx in exhausts via the NH3 Selective Catalytic Reduction (SCR) method. By combining electrospinning and soft chemistry, materials are processed as nanofibers with the catalytic components (e. g. V2O5-WO3) incorporated as dopant...

Deactivation of vanadia-based commercial SCR catalysts by polyphosphoric acids

DEFF Research Database (Denmark)

Castellino, Francesco; Rasmussen, Søren Birk; Jensen, Anker Degn

2008-01-01

Commercial vanadia-based SCR monoliths have been exposed to flue gases in a pilot-scale Setup into which phosphoric acid has been added and the deactivation has been followed during the exposure time. Separate measurements by SMPS showed that the phosphoric acid formed polyphosphoric acid aerosols...

N2O and NO2 Emissions from Heavy-Duty Diesel Trucks with Advanced Emission Controls

Science.gov (United States)

Preble, C.; Harley, R.; Kirchstetter, T.

2014-12-01

Diesel engines are the largest source of nitrogen oxides (NOx) emissions nationally, and also a major contributor to the black carbon (BC) fraction of fine particulate matter (PM). Recently, diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have become standard equipment on new heavy-duty diesel trucks. However, the deliberate catalytic oxidation of engine-out nitric oxide (NO) to nitrogen dioxide (NO2) in continuously regenerating DPFs leads to increased tailpipe emission of NO2. This is of potential concern due to the toxicity of NO2 and the resulting increases in atmospheric formation of other air pollutants such as ozone, nitric acid, and fine PM. While use of SCR reduces emissions of both NO and NO2, it may lead to increased emissions of nitrous oxide (N2O), a potent greenhouse gas. Here we report results from on-road measurements of heavy-duty diesel truck emissions conducted at the Port of Oakland and the Caldecott Tunnel in the San Francisco Bay Area. Emission factors (g pollutant per kg of diesel) were linked via recorded license plates to individual truck attributes, including engine model year and installed emission control equipment. Between 2009 and 2013, the fraction of DPF-equipped trucks at the Port of Oakland increased from 2 to 99%, and median engine age decreased from 11 to 6 years. Over the same period, fleet-average emission factors for black carbon and NOx decreased by 76 ± 22% and 53 ± 8%, respectively. However, direct emissions of NO2 increased, and consequently the NO2/NOx emission ratio increased from 0.03 ± 0.02 to 0.18 ± 0.03. Older trucks retrofitted with DPFs emitted approximately 3.5 times more NO2 than newer trucks equipped with both DPF and SCR. Preliminary data from summer 2014 measurements at the Caldecott Tunnel suggest that some older trucks have negative emission factors for N2O, and that for newer trucks, N2O emission factors have changed sign and

Evaluation of the first SCR-plants in Sweden; Utvaerdering av de foersta SCR-anlaeggningarna i Sverige

Energy Technology Data Exchange (ETDEWEB)

Hanell, B [Vattenfall AB, Stockholm (Sweden); and others

1996-05-01

This report presents operational experience of SCR systems at five power plants in Sweden; the diesel cogeneration plants in Linkoeping, Oskarshamn, Skultuna and Visby and the coal fired power plant in Vaesteraas. The experience represents the first years of operation of the SCR systems. The SCR-systems involved in this project achieve the following: * Uneven flue gas flow and concentration of ammonia and NO{sub x} through the SCR reactor results in lower efficiency. Hence it is important to achieve a thorough mixing of the ammonia in the flue gas in order to achieve high NO{sub x} reduction efficiencies, * Inferior control systems can cause unnecessary ammonia slip, * The diesel plants with an operating time of a couple of thousand hours have had major problems with deposits on the catalyst surface, * Guarantees regarding the lifetime of the catalyst are important. At commissioning the catalyst has to be over-dimensioned since the system has to reach the guaranteed emissions during the whole guarantee period, * There should be enough space in the reactor to install additional catalyst layers. This project verifies that additional layers need to be installed at later stages, * The mechanical construction of the SCR-reactor is important. The efficiency decreases when there is a leakage of flue gases past the reactor, * No considerable amounts of N{sub 2}O are generated by the catalyst. 21 refs, 27 figs, 47 tabs

CONTROL OF NOX EMISSIONS FROM U.S. COAL-FIRED ELECTRIC UTILITY BOILERS

Science.gov (United States)

The paper discusses the control of nitrogen oxide (NOx) emissions from U.S. coal-fired electric utility boilers. (NOTE: In general, NOx control technologies are categorized as being either primary or secondary control technologies. Primary technologies reduce the amount of NOx pr...

Monitoring the ammonia loading of zeolite-based ammonia SCR catalysts by a microwave method

Energy Technology Data Exchange (ETDEWEB)

Reiss, S.; Schoenauer, D.; Hagen, G.; Moos, R. [University of Bayreuth, Department of Functional Materials, Bayreuth (Germany); Fischerauer, G. [University of Bayreuth, Department of Metrology and Control, Bayreuth (Germany)

2011-05-15

Exhaust gas aftertreatment systems, which reduce nitrogen oxide emissions of heavy-duty diesel engines, commonly use a selective catalytic reduction (SCR) catalyst. Currently, emissions are controlled by evaluating NO{sub x} or NH{sub 3} in the gas phase downstream the catalyst and calculating the NH{sub 3} loading via a chemical storage model. Here, a microwave-cavity perturbation method is proposed in which electromagnetic waves are excited by probe feeds and the reflected signals are measured. At distinct resonance frequencies, the reflection coefficient shows a pronounced minimum. These resonance frequencies depend almost linearly on the NH{sub 3} loading of a zeolite-based SCR catalyst. Since the NH{sub 3} loading-dependent electrical properties of the catalyst material itself are measured, the amount of stored ammonia can be determined directly and in situ. The cross-sensitivity towards water can be reduced almost completely by selecting an appropriate frequency range. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The J3 SCR model applied to resonant converter simulation

Science.gov (United States)

Avant, R. L.; Lee, F. C. Y.

1985-01-01

The J3 SCR model is a continuous topology computer model for the SCR. Its circuit analog and parameter estimation procedure are uniformly applicable to popular computer-aided design and analysis programs such as SPICE2 and SCEPTRE. The circuit analog is based on the intrinsic three pn junction structure of the SCR. The parameter estimation procedure requires only manufacturer's specification sheet quantities as a data base.

Alternative catalysts and technologies for NOx removal from biomass- and wastefired plants

DEFF Research Database (Denmark)

Schill, Leonhard

removed with the selective catalytic reduction (SCR) using a vanadia-tungsta-titania (VWT) catalyst and ammonia (NH3) as reductant. For application in coal- and gas-red power plants this technology is mature. However, when ring biomass the ue gas contains potassium in large amounts which deactivates....... The deNOx activity over Ag/Al2O3 used in ethanol-SCR is practically as much reduced as in the NH3-SCR case over the traditional VWT catalyst. Furthermore, poisoning with potassium leads to unselective oxidation of the hydrocarbons instead of NO reduction and SO2 concentrations as low as 20 ppm can....... At 150 C, in the presence of 10 % H2O, the catalyst under patenting matches the activity of the commercial VWT one at 220 C. However, ue gases at the tail-end position can contain up to 20 % H2O, increasing the temperature of activity parity to 180 C. Furthermore, the catalyst is also sensitive to SO2...

SCR in biomass and waste fuelled plants. Benchmarking of Swedish and European plants; SCR i biobraensle- och avfallseldade anlaeggningar. Erfarenheter fraan svenska och europeiska anlaeggningar

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, Barbara; Olsson, Henrik; Lindstroem, Erica

2010-11-15

In this report the state-of-art of SCR technology in biomass and waste fired plants is investigated. The aim of the investigation is to answer the question why new Swedish biomass combustion and co-combustion plants often prefer SNCR technology, whilst European waste combustion plants often choose SCR technology. In the report positives and negatives of various types of SCR installations are discussed, high-dust versus tail-end, 'normal' SCR versus low-temperature SCR, etc. Experiences, e g catalyst lifetime, deactivation and maintenance requirement, are discussed. The investigation is based partly on literature, but mainly on interviews with plant owners and with suppliers of SCR installations. The interviewed suppliers are mentioned in the reference list and the interviewed plant owners are mentioned in appendix A and B. The experiences from the Swedish and European plants are quite similar. Tail-end SCR is often operated without serious problems in both biomass and waste fuelled plants. The catalyst lifetimes are as long or even longer than for coal fired plants with high-dust SCR. In waste incineration plants high-dust SCR causes big problems and these plants are almost always equipped with tail-end SCR. In co-combustion boilers, where coal and biomass is co-combusted, high-dust SCR is more common, especially if the boilers were originally coal fired. In plants with both SNCR and high-dust SCR, i.e. slip-SCR, the SCR installation is considered to be much less of a problem. Although the activity loss of the catalyst is as quick as in conventional high-dust SCR, the catalyst can be changed less often. This is due to the fact that installed slip-SCR catalysts often are as large as conventional SCR catalysts, although less NO{sub x} reduction is required after the initial SNCR step. Thus, the catalyst lifetime is prolonged.

Control strategies for vehicular NOx emissions in Guangzhou, China

International Nuclear Information System (INIS)

Shao Min; Zhang Yuanhang; Raufer, Roger

2001-01-01

Guangzhou is a city in southern China that has experienced very rapid economic development in recent years. The city's air has very high concentrations of various pollutants, including sulphur dioxide (SO 2 , oxides of nitrogen (NOx), ozone (O 3 ) and particulate. This paper reviews the changes in air quality in the city over the past 15 years, and notes that a serious vehicular-related emissions problem has been superimposed on the traditional coal-burning problem evident in most Chinese cities. As NOx concentrations have increased, oxidants and photochemical smog now interact with the traditional SO 2 and particulate pollutants, leading to increased health risks and other environmental concerns. Any responsible NOx control strategy for the city must include vehicle emission control measures. This paper reviews control strategies designed to abate vehicle emissions to fulfill the city's air quality improvement target in 2010. A cost-effectiveness analysis suggests that, while NOx emission control is expensive, vehicular emission standards could achieve a relatively sizable emissions reduction at reasonable cost. To achieve the 2010 air quality target of NOx, advanced implementation of EURO3 standards is recommended, substituting for the EURO2 currently envisioned in the national regulations Related technical options, including fuel quality improvements and inspection/maintenance (I/M) upgrades (ASM or IM240) are assessed as well. (author)

Spectroscopic Insights into Copper-Based Microporous Zeolites for NH3-SCR of NOx and Methane-to-Methanol Activation

NARCIS (Netherlands)

Oord, R.

2017-01-01

Smog has received a lot of attention and is still a major problem in big cities all over the world. A major contribution to smog are nitrogen oxides (NOx), which are mainly produced by road transport, industrial processes and power plants. A lot of research has been put into the reduction of these

Supported Metal Zeolites as Environmental Catalysts for Reduction of NOx Molecules

International Nuclear Information System (INIS)

May Nwe Win; Tin Tin Aye; Kyaw Myo Naing; Nyunt Wynn; Maung Maung Htay

2005-09-01

The NOx contamination of air is a major pollutant due to its reaction with the volatile organic compounds, which give rise to ground level (tropospheric) ozone. It is a conventional fact that NOx are one of the major components of car exhaust. In view of that fact, to sustain the tropospheric ozone is to reduce the amount of NOx in the air. Therefore, this paper is concerned with the catalytic activity of Fe-loaded zeolite and Cu-loaded zeolite used to decompose NIOx by SCR (selective catalytic reduction) reaction with very high activity have been studied. Their preparations, characterization by XRD, FT-IR and SEM were also studied. Fe and Cu containig were prepared by soild state ion-exchange method under ambient presure and at the temperature of 600C for 4 hours. From this study, selective catalytic reduction rection was observed, showing about 87% conversion of the NOx molecule with the corresponding optimum amount of catalyst (1.0+-0.5)g working under the reactor space volume of 30cm3 at ambient temperature (30-32)C

Sulfated Zirconia as Alkali-Resistant Support for Catalytic NOx Removal

DEFF Research Database (Denmark)

The use of bio-fuels as alternatives to traditional fossil fuels has attracted much attention recent years since bio-fuels belong to a family of renewable types of energy sources and do not contribute to the green-house effect. Selective catalytic reduction (SCR) of NOx with ammonia as reductant ...... interact with potassium stronger than active metal species. Among potential carriers, sulfated zirconia is of high interest because its acidic and textural properties can be modified by varying preparation conditions....

Post combustion methods for control of NOx emission

Energy Technology Data Exchange (ETDEWEB)

Rosenberg, H S; Curran, L M; Slack, A V; Ando, J; Oxley, J H

1980-01-01

Review of stack gas treatment methods for the control of NOx emissions. Particular emphasis is placed on status of development and factors affecting the performance of the processes. Catalytic, noncatalytic, and scrubbing processes are compared on a uniform engineering basis. Most of the active process development work is taking place in Japan. The three leading stack gas treatment techniques for NOx control are catalytic reduction with ammonia, noncatalytic reduction with ammonia, and direct scrubbing of NO with simultaneous absorption of SO2. The wet processes are much less developed than the dry processes.

Numerical Investigation of AdBlue Droplet Evaporation and Thermal Decomposition in the Context of NOx-SCR Using a Multi-Component Evaporation Model

Directory of Open Access Journals (Sweden)

Kaushal Nishad

2018-01-01

Full Text Available To cope with the progressive tightening of the emission regulations, gasoline and diesel engines will continuously require highly improved exhaust after-treatment systems. In the case of diesel engines, the selective catalytic reduction (SCR appears as one of the widely adopted technologies to reduce NOx (nitrogen oxides emissions. Thereby, with the help of available heat from exhaust gas, the injected urea–water solution (UWS turns inside the exhaust port immediately into gaseous ammonia (NH3 by evaporation of mixture and thermal decomposition of urea. The reaction and conversion efficiency mostly depend upon the evaporation and subsequent mixing of the NH3 into the exhaust gas, which in turn depends upon the engine loading conditions. Up to now, the aggregation of urea after evaporation of water and during the thermal decomposition of urea is not clearly understood. Hence, various scenarios for the urea depletion in the gaseous phase that can be envisaged have to be appraised under SCR operating conditions relying on an appropriate evaporation description. The objective of the present paper is therefore fourfold. First, a reliable multi-component evaporation model that includes a proper binary diffusion coefficient is developed for the first time in the Euler–Lagrangian CFD (computational fluid dynamics framework to account properly for the distinct evaporation regimes of adBlue droplets under various operating conditions. Second, this model is extended for thermal decomposition of urea in the gaseous phase, where, depending on how the heat of thermal decomposition of urea is provided, different scenarios are considered. Third, since the evaporation model at and around the droplet surface is based on a gas film approach, how the material properties are evaluated in the film influences the process results is reported, also for the first time. Finally, the impact of various ambient temperatures on the adBlue droplet depletion characteristics

40 CFR 52.2237 - NOX RACT and NOX conformity exemption.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false NOX RACT and NOX conformity exemption... RACT and NOX conformity exemption. Approval. EPA is approving the section 182(f) oxides of nitrogen (NOX) reasonably available control technology (RACT) and NOX conformity exemption request submitted by...

Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

Directory of Open Access Journals (Sweden)

Markus Dietrich

2017-07-01

Full Text Available The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13 was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

Science.gov (United States)

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-01-01

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. PMID:28704929

Experimental Studies for CPF and SCR Model, Control System, and OBD Development for Engines Using Diesel and Biodiesel Fuels

Energy Technology Data Exchange (ETDEWEB)

Johnson, John; Naber, Jeffrey; Parker, Gordon; Yang, Song-Lin; Stevens, Andrews; Pihl, Josh

2013-04-30

The research carried out on this project developed experimentally validated Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), and Selective Catalytic Reduction (SCR) high‐fidelity models that served as the basis for the reduced order models used for internal state estimation. The high‐fidelity and reduced order/estimator codes were evaluated by the industrial partners with feedback to MTU that improved the codes. Ammonia, particulate matter (PM) mass retained, PM concentration, and NOX sensors were evaluated and used in conjunction with the estimator codes. The data collected from PM experiments were used to develop the PM kinetics using the high‐fidelity DPF code for both NO2 assisted oxidation and thermal oxidation for Ultra Low Sulfur Fuel (ULSF), and B10 and B20 biodiesel fuels. Nine SAE papers were presented and this technology transfer process should provide the basis for industry to improve the OBD and control of urea injection and fuel injection for active regeneration of the PM in the DPF using the computational techniques developed. This knowledge will provide industry the ability to reduce the emissions and fuel consumption from vehicles in the field. Four MS and three PhD Mechanical Engineering students were supported on this project and their thesis research provided them with expertise in experimental, modeling, and controls in aftertreatment systems.

Technical presentation of SCR

CERN Multimedia

FI Department

2008-01-01

SCR Société des Composants Record, Montierchaume, France Monday 20 October 2008 from 9:45 to 12:00 – Room A Main Building (Bldg. 61/1-017) http://www.scr.fr SCR develops, manufactures and markets plastic dielectric capacitors (polypropylene, polyester, Teflon) for use in various applications: audio amplifiers, high-end loudspeakers, fans and extractors (multi-capacitance capacitors), pulsed lasers, flash lamps, defibrillators, beacons, power supplies, converters for rail traction drives, railway signalling devices, voltage dividers and multipliers, high voltage laboratories, etc. The company is renowned for its precision wire-wound resistors for use in power electronics and consumer electronics marketed under the SETA brand name. SCR is also experienced in the design and production of electronic circuits for various applications, such as speed variators for mono and three-phase motors, dimmers, passive filters for audio speakers, etc. Contact : M. Urs V. Rölli, e-mail: mailto:info@technictrade.ch.

Emission reduction from a diesel engine fueled by pine oil biofuel using SCR and catalytic converter

Science.gov (United States)

Vallinayagam, R.; Vedharaj, S.; Yang, W. M.; Saravanan, C. G.; Lee, P. S.; Chua, K. J. E.; Chou, S. K.

2013-12-01

In this work, we propose pine oil biofuel, a renewable fuel obtained from the resins of pine tree, as a potential substitute fuel for a diesel engine. Pine oil is endowed with enhanced physical and thermal properties such as lower viscosity and boiling point, which enhances the atomization and fuel/air mixing process. However, the lower cetane number of the pine oil hinders its direct use in diesel engine and hence, it is blended in suitable proportions with diesel so that the ignition assistance could be provided by higher cetane diesel. Since lower cetane fuels are prone to more NOX formation, SCR (selective catalyst reduction), using urea as reducing agent, along with a CC (catalytic converter) has been implemented in the exhaust pipe. From the experimental study, the BTE (brake thermal efficiency) was observed to be increased as the composition of pine oil increases in the blend, with B50 (50% pine oil and 50% diesel) showing 7.5% increase over diesel at full load condition. The major emissions such as smoke, CO, HC and NOX were reduced by 70.1%, 67.5%, 58.6% and 15.2%, respectively, than diesel. Further, the average emissions of B50 with SCR and CC assembly were observed to be reduced, signifying the positive impact of pine oil biofuel on atmospheric environment. In the combustion characteristics front, peak heat release rate and maximum in-cylinder pressure were observed to be higher with longer ignition delay.

Method for control of NOx emission from combustors using fuel dilution

Science.gov (United States)

Schefer, Robert W [Alamo, CA; Keller, Jay O [Oakland, CA

2007-01-16

A method of controlling NOx emission from combustors. The method involves the controlled addition of a diluent such as nitrogen or water vapor, to a base fuel to reduce the flame temperature, thereby reducing NOx production. At the same time, a gas capable of enhancing flame stability and improving low temperature combustion characteristics, such as hydrogen, is added to the fuel mixture. The base fuel can be natural gas for use in industrial and power generation gas turbines and other burners. However, the method described herein is equally applicable to other common fuels such as coal gas, biomass-derived fuels and other common hydrocarbon fuels. The unique combustion characteristics associated with the use of hydrogen, particularly faster flame speed, higher reaction rates, and increased resistance to fluid-mechanical strain, alter the burner combustion characteristics sufficiently to allow operation at the desired lower temperature conditions resulting from diluent addition, without the onset of unstable combustion that can arise at lower combustor operating temperatures.

The energy consumption and environmental impacts of SCR technology in China

Energy Technology Data Exchange (ETDEWEB)

Liang, Zengying; Ma, Xiaoqian; Lin, Hai; Tang, Yuting [School of Electric Power, Guangdong Key Laboratory of Clean Energy Technology, South China University of Technology, Guangzhou 510640 (China)

2011-04-15

Energy and environment are drawing greater attention today, particularly with the rapid development of the economy and increase consumption of energy in China. At present, coal-fired power plants are mainly responsible for atmospheric air pollution. The selective catalytic reduction (SCR) technology is a highly effective method for NO{sub X} control. The present study identified and quantified the energy consumption and the environmental impacts of SCR system throughout the whole life cycle, including production and transportation of manufacturing materials, installation and operation of SCR technology. The analysis was conducted with the utilization of life cycle assessment (LCA) methodology which provided a quantitative basis for assessing potential improvements in the environmental performance of the system. The functional unit of the study was 5454 t NO{sub X} emission from an existing Chinese pulverized coal power plant for 1 year. The current study compared life cycle emissions from two types of de-NO{sub X} technologies, namely the SCR technology and the selective non-catalytic reduction (SNCR) technology, and the case that NO{sub X} was emitted into atmosphere directly. The results showed that the environmental impact loading resulting from SCR technology (66810 PET{sub 2000}) was smaller than that of flue gas emitted into atmosphere directly (164121 PET{sub 2000}) and SNCR technology (105225 PET{sub 2000}). More importantly, the SCR technology is much more effective at the elimination of acidification and nutrient enrichment than SNCR technology and the case that NO{sub X} emitted into atmosphere directly. This SCR technology is more friendly to the environment, and can play an important role in NO{sub X} control for coal-fired power plants as well as industrial boilers. (author)

Co-controlling CO2 and NOx emission in China's cement industry: An optimal development pathway study

Directory of Open Access Journals (Sweden)

Xiang-Zhao Feng

2018-03-01

Full Text Available It is of important practical significance to reduce NOx emission and CO2 emission in China's cement industry. This paper firstly identifies key factors that influence China's future cement demand, and then uses the Gompertz model to project China's future cement demand and production. Furthermore, the multi-pollutant abatement planning model (MAP was developed based on the TIMES model to analyze the co-benefits of CO2 and NOx control in China's cement industry. During modeling analysis, three scenarios such as basic as usual scenario (BAU, moderately low carbon scenario (MLC, and radically low carbon scenario (RLC, were built according to different policy constraints and emission control goals. Moreover, the benefits of co-controlling NOx and CO2 emission in China's cement industry have been estimated. Finally, this paper proposes a cost-efficient, green, and low carbon development roadmap for the Chinese cement sector, and puts forwards countermeasures as follows: first, different ministries should enhance communication and coordination about how to promote the co-control of NOx and CO2 in cement industry. Second, co-control technology list should be issued timely for cement industry, and the R&D investment on new technologies and demonstration projects should be increased. Third, the phase-out of old cement capacity needs to be continued at policy level. Fourth, it is important to scientifically evaluate the relevant environmental impact and adverse motivation of ammonia production by NOx removal requirement in cement industry. Keywords: Cement industry, CO2 abatement, NOx reduction, Co-benefit analysis

Amorphous saturated Cerium-Tungsten-Titanium oxide nanofibers catalysts for NOx selective catalytic reaction

DEFF Research Database (Denmark)

Dankeaw, Apiwat; Gualandris, Fabrizio; Silva, Rafael Hubert

2018-01-01

experiments at the best working conditions (dry and in absence of SO2) are performed to characterize the intrinsic catalytic behavior of the new catalysts. At temeprature lower than 300 °C, superior NOx conversion properties of the amorphous TiOx nanofibers over the crystallized TiO2 (anatase) nanofibers......Herein for the first time, Ce0.184W0.07Ti0.748O2-δ nanofibers are prepared by electrospinning to serve as catalyst in the selective catalytic reduction (SCR) process. The addition of cerium is proven to inhibit crystallization of TiO2, yielding an amorphous TiOx-based solid solution stable up...... temperatures (catalysts in a wide range...

The enhanced resistance to K deactivation of Ce/TiO2 catalyst for NH3-SCR reaction by the modification with P

Science.gov (United States)

Li, Ming-yuan; Guo, Rui-tang; Hu, Chang-xing; Sun, Peng; Pan, Wei-guo; Liu, Shu-ming; Sun, Xiao; Liu, Shuai-wei; Liu, Jian

2018-04-01

The deactivation of SCR catalyst caused by K species contained in the fly ash would suppress its DeNOx performance. In this study, it was manifested that the modification of Ce/TiO2 catalyst with P could enhance its K tolerance. To understand the promotion mechanism, the fresh and poisoned catalyst samples were subjected to the characterization techniques including BET, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFT. The results elucidated that the introduction of P species could increase the reducibility of Ce species and generate more surface chemisorbed oxygen, along with the strengthened surface acidity for NH3 adsorption. It seemed that the NH3-SCR reaction mechanism over Ce/TiO2 catalyst was a combination of L-H mechanism (reason for its good K resistance.

Pilot-Scale Demonstration of ALTA for NOx Control in Pulverized Coal-Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Andrew Fry; Devin Davis; Marc Cremer; Bradley Adams

2008-04-30

This report describes computational fluid dynamics (CFD) modeling and pilot-scale testing conducted to demonstrate the ability of the Advanced Layered Technology Approach (ALTA) to reduce NO{sub x} emissions in a pulverized coal (PC) boiler. Testing specifically focused on characterizing NO{sub x} behavior with deep burner staging combined with Rich Reagent Injection (RRI). Tests were performed in a 4 MBtu/hr pilot-scale furnace at the University of Utah. Reaction Engineering International (REI) led the project team which included the University of Utah and Combustion Components Associates (CCA). Deep burner staging and RRI, combined with selective non-catalytic reduction (SNCR), make up the Advanced Layered Technology Approach (ALTA) for NO{sub x} reduction. The application of ALTA in a PC environment requires homogenization and rapid reaction of post-burner combustion gases and has not been successfully demonstrated in the past. Operation of the existing low-NO{sub x} burner and design and operation of an application specific ALTA burner was guided by CFD modeling conducted by REI. Parametric pilot-scale testing proved the chemistry of RRI in a PC environment with a NOx reduction of 79% at long residence times and high baseline NOx rate. At representative particle residence times, typical operation of the dual-register low-NO{sub x} burner provided an environment that was unsuitable for NO{sub x} reduction by RRI, showing no NOx reduction. With RRI, the ALTA burner was able to produce NO{sub x} emissions 20% lower than the low-NO{sub x} burner, 76 ppmv vs. 94 ppmv, at a burner stoichiometric ratio (BSR) of 0.7 and a normalized stoichiometric ratio (NSR) of 2.0. CFD modeling was used to investigate the application of RRI for NO{sub x} control on a 180 MW{sub e} wall-fired, PC boiler. A NO{sub x} reduction of 37% from baseline (normal operation) was predicted using ALTA burners with RRI to produce a NO{sub x} emission rate of 0.185 lb/MBtu at the horizontal nose of

Characterization of NOx emission in the suburbs of Tokyo based on simultaneous and real-time observations of atmospheric Ox and NOx

Science.gov (United States)

Matsumoto, J.

2013-12-01

Nitrogen oxides, NOx (NO, NO2), and volatile organic compounds, VOCs, are important as precursors of photochemical oxidants (tropospheric ozone, O3). To predict and control photochemical oxidants, NOx emission should be captured precisely. In addition, the ratio of NO2/NOx in the exhaust gas is also important as the initial balance between NO and NO2 in the atmosphere. Monitoring the NO2/NOx ratio in the exhaust gases is essential. Especially, the influence of the NOx emission on the real atmosphere should be explored. However, conversion reactions among NO, NO2 and O3 are typically in the time scale of minutes. The NO2/NOx ratio can change rapidly just after emission. Real-time observations of these compounds in the second time scale are essential. In view of photochemical oxidant, near emission sources of NO, ozone concentration can be easily perturbed by reaction with locally emitted NO. As an index of oxidant, the sum of O3 and NO2 (Ox = O3 + NO2) is useful. In this study, a simultaneous and real-time analyzer of atmospheric Ox and NOx has been developed utilizing the dual NO2 detectors based on laser-induced fluorescence technique (LIF), and characterization of NOx emission was explored through the observations of Ox and NOx in the suburbs of Tokyo. The dual LIF detectors consisted of one laser head, two LIF cells, and one common vacuum pump. As the Ox monitor, the excess NO was added to the sample and O3 was converted to NO2, and then the sum of O3 and NO2 in the sample was quantified at the 1st LIF cell. As the NOx monitor, the excess O3 was added to the sample and NO was converted to NO2, and then the sum of NO and NO2 in the sample was quantified at the 2nd LIF cell. Both the ';Ox' and ';NOx' channels in the dual LIF analyzer were simultaneously monitoring Ox and NOx in the sample air, respectively. The temporal resolution of observed data was 1 s. Typical conversion efficiencies of O3 and NO to NO2 were more than 0.98. The lower detection limits were 0

NOx from cement production - reduction by primary measures

DEFF Research Database (Denmark)

Jensen, Lars Skaarup

1999-01-01

cement production processes cement is typically produced by thermally treating a mixture of limestone and clay minerals in kiln systems consisting of a rotary kiln and a calciner. Clinker burning at a temperature of about 1450 °C takes place in the internally fired rotary kiln and calcination, which...... rotary kilns, while NOx formation from fuel-N and reduction of NOx take place in calciners. NOx formation in the rotary kiln is mainly governed by the necessary clinker burning temperature and is not very amenable to control, while net NOx formation in calciners depends strongly on calciner design......, calciner operation, fuel properties and on the NOx level from the rotary kiln. The low-NOx calciner types presently marketed are based on combinations of reburning, air staging and temperature control and seem equivalent in their ability to restrict NOx formation. If fuels with a significant volatile...

Remarkably enhanced density and specific activity of active sites in Al-rich Cu-, Fe- and Co-beta zeolites for selective catalytic reduction of NOx

Czech Academy of Sciences Publication Activity Database

Sazama, Petr; Pilař, Radim; Mokrzycki, Lukasz; Vondrová, Alena; Kaucký, Dalibor; Plšek, Jan; Sklenák, Štěpán; Šťastný, Petr; Klein, Petr

2016-01-01

Roč. 189, JUL 2016 (2016), s. 65-74 ISSN 0926-3373 R&D Projects: GA TA ČR(CZ) TH01021259 Institutional support: RVO:61388955 Keywords : SCR-NOx * Al-rich beta zeolite (*BEA) * Cobalt Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.446, year: 2016

The SS-SCR Scheme for Dynamic Spectrum Access

Directory of Open Access Journals (Sweden)

Vinay Thumar

2012-01-01

Full Text Available We integrate the two models of Cognitive Radio (CR, namely, the conventional Sense-and-Scavenge (SS Model and Symbiotic Cooperative Relaying (SCR. The resultant scheme, called SS-SCR, improves the efficiency of spectrum usage and reliability of the transmission links. SS-SCR is enabled by a suitable cross-layer optimization problem in a multihop multichannel CR network. Its performance is compared for different PU activity patterns with those schemes which consider SS and SCR separately and perform disjoint resource allocation. Simulation results depict the effectiveness of the proposed SS-SCR scheme. We also indicate the usefulness of cloud computing for a practical deployment of the scheme.

Enhanced catalytic activity over MIL-100(Fe) loaded ceria catalysts for the selective catalytic reduction of NOx with NH₃ at low temperature.

Science.gov (United States)

Wang, Peng; Sun, Hong; Quan, Xie; Chen, Shuo

2016-01-15

The development of catalysts for selective catalytic reduction (SCR) reactions that are highly active at low temperatures and show good resistance to SO2 and H2O is still a challenge. In this study, we have designed and developed a high-performance SCR catalyst based on nano-sized ceria encapsulated inside the pores of MIL-100(Fe) that combines excellent catalytic power with a metal organic framework architecture synthesized by the impregnation method (IM). Transmission electron microscopy (TEM) revealed the encapsulation of ceria in the cavities of MIL-100(Fe). The prepared IM-CeO2/MIL-100(Fe) catalyst shows improved catalytic activity both at low temperatures and throughout a wide temperature window. The temperature window for 90% NOx conversion ranges from 196 to 300°C. X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analysis indicated that the nano-sized ceria encapsulated inside MIL-100(Fe) promotes the production of chemisorbed oxygen on the catalyst surface, which greatly enhances the formation of the NO2 species responsible for fast SCR reactions. Copyright © 2015 Elsevier B.V. All rights reserved.

Regeneration of Pt-catalysts deactivated in municipal waste flue gas with H2/N2 and the effect of regeneration step on the SCR catalyst

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren Birk; Kustov, Arkadii

Municipal waste flue gas was previously found to deactivate the Pt-based CO oxidation catalyst severely. In the specific case studied, siloxanes were found to cause the deactivation. An on-site method for complete regeneration of the catalyst activity was found without shutdown of the flue gas...... stream, i.e. by in situ treatment of the Pt-catalyst by reductive H2-gas. However, introduction of H2 gas in the gas stream could also affect other units in the tail pipe gas cleaning system. Of special interest here, is the effect of hydrogen gas on the performance of the deNOx + SCR catalytic process...

Synthesis of FBD-based PLC design from NuSCR formal specification

International Nuclear Information System (INIS)

Yoo, Junbeom; Cha, Sungdeok; Kim, Chang Hwoi; Song, Duck Yong

2005-01-01

NuSCR is a formal specification language to document requirements for real-time embedded software with nuclear engineering applications in mind. Domain experts actively participated in selecting how to best represent various aspects. It uses tabular notations to specify required computations and automata to document state- or time-dependent behavior. As programmable logic controllers (PLCs) are widely used to implement real-time embedded software, synthesis of PLC code from a formal specification is desirable if transformation rules can be rigorously defined. In addition to improved productivity, results of safety analysis performed on requirements remain valid. In this paper, we demonstrate how NuSCR specification can be translated into semantically equivalent function block diagram (FBD) code. The process, except the initial phase where user provides information on missing or implicit details, is automated. Since executable code can be automatically generated using CASE tools from FBD, much of software development is automated. Proposed technique is currently being used in developing reactor protection system (RPS) for nuclear power plants in Korea, and experience to date has been positive. We demonstrate the proposed approach using the fixed set-point rising trip which is one of the most complex trip logics included in the RPS

Evaluation of Mercury Emissions from Coal-Fired Facilities with SCR and FGD Systems

Energy Technology Data Exchange (ETDEWEB)

J. A. Withum; S. C. Tseng; J. E. Locke

2006-01-31

CONSOL Energy Inc., Research & Development (CONSOL), with support from the U.S. Department of Energy, National Energy Technology Laboratory (DOE) and the Electric Power Research Institute (EPRI), is evaluating the effects of selective catalytic reduction (SCR) on mercury (Hg) capture in coal-fired plants equipped with an electrostatic precipitator (ESP)--wet flue gas desulfurization (FGD) combination or a spray dyer absorber--fabric filter (SDA-FF) combination. In this program CONSOL is determining mercury speciation and removal at 10 coal-fired facilities. The principal purpose of this work is to develop a better understanding of the potential mercury removal ''co-benefits'' achieved by NO{sub x}, and SO{sub 2} control technologies. It is expected that these data will provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. Ultimately, this insight could help to design and operate SCR and FGD systems to maximize mercury removal. The objectives are (1) to evaluate the effect of SCR on mercury capture in the ESP-FGD and SDA-FF combinations at coal-fired power plants, (2) evaluate the effect of SCR catalyst degradation on mercury capture; (3) evaluate the effect of low load operation on mercury capture in an SCR-FGD system, and (4) collect data that could provide the basis for fundamental scientific insights into the nature of mercury chemistry in flue gas, the catalytic effect of SCR systems on mercury speciation and the efficacy of different FGD technologies for mercury capture. This document, the ninth in a series of topical reports, describes the results and analysis of mercury sampling performed on Unit 1 at Plant 7, a 566 MW unit burning a bituminous coal containing 3.6% sulfur. The unit is equipped with a SCR, ESP, and wet FGD to control NO{sub x}, particulate, and SO

Three-Dimensional Composite Nanostructures for Lean NOx Emission Control

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian

2013-07-31

This final report to the Department of Energy (DOE) and National Energy Technology Laboratory (NETL) for DE-EE0000210 covers the period from October 1, 2009 to July 31, 2013. Under this project, DOE awarded UConn about $1,248,242 to conduct the research and development on a new class of 3D composite nanostructure based catalysts for lean NOx emission control. Much of the material presented here has already been submitted to DOE/NETL in quarterly technical reports. In this project, through a scalable solution process, we have successfully fabricated a new class of catalytic reactors, i.e., the composite nanostructure array (nano-array) based catalytic converters. These nanocatalysts, distinct from traditional powder washcoat based catalytic converters, directly integrate monolithic substrates together with nanostructures with well-defined size and shape during the scalable hydrothermal process. The new monolithic nanocatalysts are demonstrated to be able to save raw materials including Pt-group metals and support metal oxides by an order of magnitude, while perform well at various oxidation (e.g., CO oxidation and NO oxidation) and reduction reactions (H{sub 2} reduction of NOx) involved in the lean NOx emissions. The size, shape and arrangement of the composite nanostructures within the monolithic substrates are found to be the key in enabling the drastically reduced materials usage while maintaining the good catalytic reactivity in the enabled devices. The further understanding of the reaction kinetics associated with the unique mass transport and surface chemistry behind is needed for further optimizing the design and fabrication of good nanostructure array based catalytic converters. On the other hand, the high temperature stability, hydrothermal aging stability, as well as S-poisoning resistance have been investigated in this project on the nanocatalysts, which revealed promising results toward good chemical and mechanical robustness, as well as S

Mordenite - Type Zeolite SCR Catalysts with Iron or Copper

DEFF Research Database (Denmark)

2012-01-01

Cu/mordenite catalysts were found to be highly active for the SCR of NO with NH3 and exhibited high resistance to alkali poisoning. Redox and acidic properties of Cu/mordenite were well preserved after poisoning with potassium unlike that of vanadium catalysts. Fe-mordenite catalysts also reveale...... to be essential requirements for the high alkali resistance. Mordenite-type zeolite based catalysts could therefore be attractive alternatives to conventional SCR catalysts for biomass fired power plant flue gas treatment....

Dedicated exhaust gas recirculation control systems and methods

Science.gov (United States)

Sczomak, David P.; Narayanaswamy, Kushal; Keating, Edward J.

2018-05-01

An engine control system of a vehicle includes a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry. The first cylinder outputs exhaust to a first three way catalyst (TWC), and the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve. An EGR control module controls opening of the EGR valve to: (i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst; and (ii) a conduit that recirculates exhaust back to an intake system of the engine.

NOx CONTROL OPTIONS AND INTEGRATION FOR US COAL FIRED BOILERS

International Nuclear Information System (INIS)

Mike Bockelie; Marc Cremer; Kevin Davis; Connie Senior; Bob Hurt; Eric Suuberg; Eric Eddings; Larry Baxter

2002-01-01

This is the sixth Quarterly Technical Report for DOE Cooperative Agreement No: DE-FC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. This program contains multiple tasks and good progress is being made on all fronts. Preliminary results from laboratory and field tests of a corrosion probe to predict waterwall wastage indicate good agreement between the electrochemical noise corrosion rates predicted by the probe and corrosion rates measured by a surface profilometer. Four commercial manufacturers agreed to provide catalyst samples to the program. BYU has prepared two V/Ti oxide catalysts (custom, powder form) containing commercially relevant concentrations of V oxide and one containing a W oxide promoter. Two pieces of experimental apparatus being built at BYU to carry out laboratory-scale investigations of SCR catalyst deactivation are nearly completed. A decision was made to carry out the testing at full-scale power plants using a slipstream of gas instead of at the University of Utah pilot-scale coal combustor as originally planned. Design of the multi-catalyst slipstream reactor was completed during this quarter. One utility has expressed interest in hosting a long-term test at one of their plants that co-fire wood with coal. Tests to study ammonia adsorption onto fly ash have clearly established that the only routes that can play a role in binding significant amounts of ammonia to the ash surface, under practical ammonia slip conditions, are those that must involve co-adsorbates

HYBRID SELECTIVE NON-CATALYTIC REDUCTION (SNCR)/SELECTIVE CATALYTIC REDUCTION (SCR) DEMONSTRATION FOR THE REMOVAL OF NOx FROM BOILER FLUE GASES

Energy Technology Data Exchange (ETDEWEB)

Jerry B. Urbas

1999-05-01

The U. S. Department of Energy (DOE), Electric Power Research Institute (EPRI), Pennsylvania Electric Energy Research Council, (PEERC), New York State Electric and Gas and GPU Generation, Inc. jointly funded a demonstration to determine the capabilities for Hybrid SNCR/SCR (Selective Non-Catalytic Reduction/Selective Catalytic Reduction) technology. The demonstration site was GPU Generation's Seward Unit No.5 (147MW) located in Seward Pennsylvania. The demonstration began in October of 1997 and ended in December 1998. DOE funding was provided through Grant No. DE-FG22-96PC96256 with T. J. Feeley as the Project Manager. EPRI funding was provided through agreements TC4599-001-26999 and TC4599-002-26999 with E. Hughes as the Project Manager. This project demonstrated the operation of the Hybrid SNCR/SCR NO{sub x} control process on a full-scale coal fired utility boiler. The hybrid technology was expected to provide a cost-effective method of reducing NO{sub x} while balancing capital and operation costs. An existing urea based SNCR system was modified with an expanded-duct catalyst to provide increased NO{sub x} reduction efficiency from the SNCR while producing increased ammonia slip levels to the catalyst. The catalyst was sized to reduce the ammonia slip to the air heaters to less than 2 ppm while providing equivalent NO{sub x} reductions. The project goals were to demonstrate hybrid technology is capable of achieving at least a 55% reduction in NO{sub x} emissions while maintaining less than 2ppm ammonia slip to the air heaters, maintain flyash marketability, verify the cost benefit and applicability of Hybrid post combustion technology, and reduce forced outages due to ammonium bisulfate (ABS) fouling of the air heaters. Early system limitations, due to gas temperature stratification, restricted the Hybrid NO{sub x} reduction capabilities to 48% with an ammonia slip of 6.1 mg/Nm{sup 3} (8 ppm) at the catalyst inlet. After resolving the stratification

Harmonic Distortion Performance of Multi Three-Phase SCR-Fed Drive Systems with Controlled DC-Link Current under Unbalanced Grid

DEFF Research Database (Denmark)

Soltani, Hamid; Davari, Pooya; Blaabjerg, Frede

2017-01-01

. In this paper, the main aim is to analyze the effects of the grid unbalanced voltage on the multi-unit three-phase ASDs with the Silicon-Controlled Rectifier (SCR)-fed front-end rectifiers, where the DC-link current is controlled utilizing an Electronic Inductor (EI) technique. In this respect, the main...

Dynamic flow control strategies of vehicle SCR Urea Dosing System

Science.gov (United States)

Lin, Wei; Zhang, Youtong; Asif, Malik

2015-03-01

Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine's operating conditions. That will lead to low NO X conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between -8% and 10% to -4% and 2% and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms. The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NO X emission remains almost unchanged. The trade-off between NO X conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine's operating conditions quickly.

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Temi Linjewile; Connie Senior; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding

2004-03-31

This is the fifteenth Quarterly Technical Report for DOE Cooperative Agreement No: DE-FC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. At AEP's Gavin Plant, data from the corrosion probes showed that corrosion rate increased as boiler load was increased. During an outage at the plant, the drop in boiler load, sensor temperature and corrosion rate could all be seen clearly. Restarting the boiler saw a resumption of corrosion activity. This behavior is consistent with previous observations made at a 600MWe utility boiler. More data are currently being examined for magnitudes of corrosion rates and changes in boiler operating conditions. Considerable progress was made this quarter in BYU's laboratory study of catalyst deactivation. Surface sulfation appears to partially suppress NO adsorption when the catalyst is not exposed to NH3; NH3 displaces surface-adsorbed NO on SCR catalysts and surface sulfation increases the amount of adsorbed NH3, as confirmed by both spectroscopy and TPD experiments. However, there is no indication of changes in catalyst activity despite changes in the amount of adsorbed NH3. A monolith test reactor (MTR), completed this quarter, provided the first comparative data for one of the fresh and field-exposed monolith SCR catalysts yet developed in this project. Measurements of activity on one of the field-exposed commercial monolith catalysts do not show significant changes in catalyst activity (within experimental error) as compared to the fresh catalyst. The exposed surface of the sample contains large amounts of Ca and Na, neither of which is present in the fresh sample, even after removal of visibly obvious fouling deposits. However, these fouling compounds do

HYBRID SELECTIVE NON-CATALYTIC REDUCTION (SNCR)/SELECTIVE CATALYTIC REDUCTION (SCR) DEMONSTRATION FOR THE REMOVAL OF NOx FROM BOILER FLUE GASES; FINAL

International Nuclear Information System (INIS)

Jerry B. Urbas

1999-01-01

The U. S. Department of Energy (DOE), Electric Power Research Institute (EPRI), Pennsylvania Electric Energy Research Council, (PEERC), New York State Electric and Gas and GPU Generation, Inc. jointly funded a demonstration to determine the capabilities for Hybrid SNCR/SCR (Selective Non-Catalytic Reduction/Selective Catalytic Reduction) technology. The demonstration site was GPU Generation's Seward Unit No.5 (147MW) located in Seward Pennsylvania. The demonstration began in October of 1997 and ended in December 1998. DOE funding was provided through Grant No. DE-FG22-96PC96256 with T. J. Feeley as the Project Manager. EPRI funding was provided through agreements TC4599-001-26999 and TC4599-002-26999 with E. Hughes as the Project Manager. This project demonstrated the operation of the Hybrid SNCR/SCR NO(sub x) control process on a full-scale coal fired utility boiler. The hybrid technology was expected to provide a cost-effective method of reducing NO(sub x) while balancing capital and operation costs. An existing urea based SNCR system was modified with an expanded-duct catalyst to provide increased NO(sub x) reduction efficiency from the SNCR while producing increased ammonia slip levels to the catalyst. The catalyst was sized to reduce the ammonia slip to the air heaters to less than 2 ppm while providing equivalent NO(sub x) reductions. The project goals were to demonstrate hybrid technology is capable of achieving at least a 55% reduction in NO(sub x) emissions while maintaining less than 2ppm ammonia slip to the air heaters, maintain flyash marketability, verify the cost benefit and applicability of Hybrid post combustion technology, and reduce forced outages due to ammonium bisulfate (ABS) fouling of the air heaters. Early system limitations, due to gas temperature stratification, restricted the Hybrid NO(sub x) reduction capabilities to 48% with an ammonia slip of 6.1 mg/Nm(sup 3) (8 ppm) at the catalyst inlet. After resolving the stratification problem

HiSCR (Hidradenitis Suppurativa Clinical Response)

DEFF Research Database (Denmark)

Kimball, B. A.; Sobell, J. M.; Zouboulis, C C

2016-01-01

Background: Determining treatment response for patients with hidradenitis suppurativa (HS) can be challenging due to limitations of current disease activity evaluations. Objective: Evaluate the novel, validated endpoint, Hidradenitis Suppurativa Clinical Response (HiSCR) and its utility as an out......Background: Determining treatment response for patients with hidradenitis suppurativa (HS) can be challenging due to limitations of current disease activity evaluations. Objective: Evaluate the novel, validated endpoint, Hidradenitis Suppurativa Clinical Response (HiSCR) and its utility...... as an outcome measure. Methods: Patients with baseline total abscess and inflammatory nodule count (AN count) of at least three and draining fistula count of 20 or fewer comprised the post hoc subpopulation analysed. HiSCR (at least a 50% reduction in total AN count, with no increase in abscess count...... week, or placebo (1 : 1 : 1). Results: The subpopulation included 132 (85.7%) patients; 70.5% women and 73.5% white. At week 16, HiSCR was achieved by 54.5% receiving weekly adalimumab, 33.3% every other week, and 25.6% placebo and HS-PGA Response was achieved by 20.5% receiving weekly adalimumab, 6...

Operational Choices for Risk Aggregation in Insurance: PSDization and SCR Sensitivity

Directory of Open Access Journals (Sweden)

Xavier Milhaud

2018-04-01

Full Text Available This work addresses crucial questions about the robustness of the PSDization process for applications in insurance. PSDization refers to the process that forces a matrix to become positive semidefinite. For companies using copulas to aggregate risks in their internal model, PSDization occurs when working with correlation matrices to compute the Solvency Capital Requirement (SCR. We examine how classical operational choices concerning the modelling of risk dependence impacts the SCR during PSDization. These operations refer to the permutations of risks (or business lines in the correlation matrix, the addition of a new risk, and the introduction of confidence weights given to the correlation coefficients. The use of genetic algorithms shows that theoretically neutral transformations of the correlation matrix can surprisingly lead to significant sensitivities of the SCR (up to 6%. This highlights the need for a very strong internal control around the PSDization step.

Mechanistic Investigation of the Reduction of NOx over Pt- and Rh-Based LNT Catalysts

Directory of Open Access Journals (Sweden)

Lukasz Kubiak

2016-03-01

Full Text Available The influence of the noble metals (Pt vs. Rh on the NOx storage reduction performances of lean NOx trap catalysts is here investigated by transient micro-reactor flow experiments. The study indicates a different behavior during the storage in that the Rh-based catalyst showed higher storage capacity at high temperature as compared to the Pt-containing sample, while the opposite is seen at low temperatures. It is suggested that the higher storage capacity of the Rh-containing sample at high temperature is related to the higher dispersion of Rh as compared to Pt, while the lower storage capacity of Rh-Ba/Al2O3 at low temperature is related to its poor oxidizing properties. The noble metals also affect the catalyst behavior upon reduction of the stored NOx, by decreasing the threshold temperature for the reduction of the stored NOx. The Pt-based catalyst promotes the reduction of the adsorbed NOx at lower temperatures if compared to the Rh-containing sample, due to its superior reducibility. However, Rh-based material shows higher reactivity in the NH3 decomposition significantly enhancing N2 selectivity. Moreover, formation of small amounts of N2O is observed on both Pt- and Rh-based catalyst samples only during the reduction of highly reactive NOx stored at 150 °C, where NOx is likely in the form of nitrites.

METHANE de-NOX for Utility PC Boilers

Energy Technology Data Exchange (ETDEWEB)

Bruce Bryan; Serguei Nester; Joseph Rabovitser; Stan Wohadlo

2005-09-30

The overall project objective is the development and validation of an innovative combustion system, based on a novel coal preheating concept prior to combustion, that can reduce NO{sub x} emissions to 0.15 lb/million Btu or less on utility pulverized coal (PC) boilers. This NO{sub x} reduction should be achieved without loss of boiler efficiency or operating stability, and at more than 25% lower levelized cost than state-of-the-art SCR technology. A further objective is to ready technology for full-scale commercial deployment to meet the market demand for NO{sub x} reduction technologies. Over half of the electric power generated in the U.S. is produced by coal combustion, and more than 80% of these units utilize PC combustion technology. Conventional measures for NOx reduction in PC combustion processes rely on combustion and post-combustion modifications. A variety of combustion-based NO{sub x} reduction technologies are in use today, including low-NO{sub x} burners (LNBs), flue gas recirculation (FGR), air staging, and natural gas or other fuel reburning. Selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) are post-combustion techniques. NO{sub x} reduction effectiveness from these technologies ranges from 30 to 60% and up to 90-93% for SCR. Typically, older wall-fired PC burner units produce NO{sub x} emissions in the range of 0.8-1.6 lb/million Btu. Low-NO{sub x} burner systems, using combinations of fuel staging within the burner and air staging by introduction of overfire air in the boiler, can reduce NO{sub x} emissions by 50-60%. This approach alone is not sufficient to meet the desired 0.15 lb/million Btu NO{sub x} standard with a range of coals and boiler loads. Furthermore, the heavy reliance on overfire air can lead to increased slagging and corrosion in furnaces, particularly with higher-sulfur coals, when LNBs are operated at sub-stoichiometric conditions to reduce fuel-derived NOx in the flame. Therefore, it is desirable

System and method for controlling an engine based on ammonia storage in multiple selective catalytic reduction catalysts

Science.gov (United States)

Sun, MIn; Perry, Kevin L.

2015-11-20

A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Deactivation of SCR catalysts by potassium: A study of potential alkali barrier materials

DEFF Research Database (Denmark)

Olsen, Brian Kjærgaard; Kügler, Frauke; Castellino, Francesco

2017-01-01

The use of coatings in order to protect vanadia based SCR catalysts against potassium poisoning has been studied by lab- and pilot-scale experiments. Three-layer pellets, consisting of a layer ofa potential coating material situated between layers of fresh and potassium poisoned SCR catalyst, were...... the coating process. Potassium had to some extent penetrated the MgO coat, and SEM analysis revealed it to be rather thick and fragile. Despite these observations, the coating did protect the SCR catalyst against potassium poisoning to some degree, leaving promise of further optimization....... used to test the ability of the barrier layer to block the diffusion of potassium across the pellet. Of MgO, sepiolite and Hollandite manganese oxide, MgO was the most effective potassium barrier, and no potassium was detected in the MgO layer upon exposure to SCR conditions for 7 days. Two monoliths...

Adaptive Model Predictive Control of Diesel Engine Selective Catalytic Reduction (SCR) Systems

Science.gov (United States)

McKinley, Thomas L.

2009-01-01

Selective catalytic reduction or SCR is coming into worldwide use for diesel engine emissions reduction for on- and off-highway vehicles. These applications are characterized by broad operating range as well as rapid and unpredictable changes in operating conditions. Significant nonlinearity, input and output constraints, and stringent performance…

Hydrolysis of isocyanic acid on SCR catalysts

Energy Technology Data Exchange (ETDEWEB)

Elsener, M; Kleemann, M; Koebel, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1999-08-01

Standard SCR catalysts possess high activity for the hydrolysis of HNCO and thus explain the suitability of urea as a selective reducing agent for NO{sub x}. At high space velocities HNCO-slip can get perceptible over the entire temperature range. This can be attributed to the fact that the temperature dependence is strong for the SCR reaction, but weak for the hydrolysis reaction. (author) 3 figs., 5 refs.

The protective effect of SCR(15-18) on cerebral ischemia-reperfusion injury.

Science.gov (United States)

Li, Shu; Xian, Jinhong; He, Li; Luo, Xue; Tan, Bing; Yang, Yongtao; Liu, Gaoke; Wang, Zhengqing

2011-10-01

Soluble complement receptor type 1 (sCR1), a potent inhibitor of complement activation, has been shown to protect brain cells against cerebral ischemic/reperfusion (CI/R) injury due to its decay-accelerating activity for C3/C5 convertase and co-factor activity for C3b/C4b degradation. However, the effect of short consensus repeats (SCRs) 15-18, one of active domains of sCR1 with high C3b/C4b degradability, has not been demonstrated. Here, we investigated the protective effect of recombinant SCR(15-18) protein in middle cerebral artery occlusion (MCAO)-induced focal CI/R injury. Recombinant SCR(15-18) protein was successfully expressed in Escherichia coli and refolded to its optimal bioactivity. Seventy-five Sprague-Dawley rats were randomly assigned into three groups: sham-operated group, CI/R group, and SCR(15-18)+CI/R group pretreated with 20 mg/kg SCR(15-18) protein. After 2 hours of MCAO and subsequent 24 hours of reperfusion, rats were evaluated for neurological deficits and cerebral infarction. Polymorphonuclear leukocyte accumulation, C3b deposition, and morphological changes in cerebral tissue were also estimated. SCR(15-18) pretreatment induced a 20% reduction of infarct size and an improvement of neurological function with 22·2% decrease of neurological deficit scores. Inhibition of cerebral neutrophils infiltration by SCR(15-18) was indicated from the reduction of myeloperoxidase activity in SCR(15-18)+CI/R rats. Decreased C3b deposition and improved morphological changes were also found in cerebral tissue of SCR(15-18)-treated rats. Our studies suggest a definitive moderately protective effect of SCR(15-18) against CI/R damage and provide preclinical experimental evidence supporting the possibility of using it as a small anti-complement therapeutic agent for CI/R injury therapy.

Control and reduction of NOx emissions on light hydrocarbons combustion in fluidized bed combustors: a technological prospection surveys; Controle e reducao de emissoes de NOx durante queima de hidrocarbonetos leves em combustores a leito fluidizado: um estudo de prospeccao tecnologica

Energy Technology Data Exchange (ETDEWEB)

Santos, Douglas Alves; Winter, Eduardo [Instituto Nacional da Propriedade Industrial (INPI), Rio de Janeiro, RJ (Brazil)

2008-07-01

The present paper aims a technological prospecting study of the main technological agents involved in industrial light hydrocarbons combustion process. More specifically, the work approaches technologies applied to nitrogen oxides emissions control and reduction. Nitrogen oxides are typically known as 'NOx' (NO, N{sub 2}O, NO{sub 2}). 'NOx' are byproducts from fuel burning in combustion systems, including also in fluidized bed combustion systems. The technological prospecting study employed 'technology foresight' as tool for evaluating the technological perspectives of the thermal generation, basis on environment protection. Such technological perspectives of the thermal generation were evaluated through invention patent documents. The query methodology for obtaining of patent documents employed a free patent base, known as ESPACENET. Additionally, the documents obtained were evaluated, considering beyond the countries and the publication dates, technological perspectives employed to 'NOx' emissions control and reduction. It is very important to highlight around 70% of the industrial technological information are just found in invention patent documents. (author)

Second Generation Advanced Reburning for High Efficiency NOx Control

Energy Technology Data Exchange (ETDEWEB)

Vladimir M. Zamansky; Peter M. Maly; Vitali V. Lissianski; Mark S. Sheldon; David Moyeda; Roy Payne

2001-06-30

viability of the AR technology. The performance goals of the project to reduce NO{sub x} by up to 95% with net emissions less than 0.06 lb/10{sup 6} Btu and to minimize other pollutants (N{sub 2}O and NH{sub 3}) to levels lower than reburning and SNCR have been met. Experimental data demonstrated that AR-Lean + SNCR and Reburning + SNCR are the most effective AR configurations, followed by AR-Lean and AR-Rich. Promoters can increase AR NO{sub x} reduction efficiency. Promoters are the most effective at small amounts of the reburning fuel (6-10% of the total fuel heat input). Promoters provide the means to improve NO{sub x} reduction and simultaneously decrease the amount of reburning fuel. Tests also showed that alkali-containing compounds are effective promoters of the AR process. When co-injected with N-agent, they provide up to 25 % improvement in NO{sub x} reduction. A detailed reaction mechanism and simplified representation of mixing were used in modeling of AR processes. Modeling results demonstrated that the model correctly described a wide range of experimental data. Mixing and thermal parameters in the model can be adjusted depending on characteristics of the combustion facility. Application of the model to the optimization of AR-Lean has been demonstrated. Economic analysis demonstrated a considerable economic advantage of AR technologies in comparison with existing commercial NO{sub x} control techniques, such as basic reburning, SNCR, and SCR. Particularly for deep NO{sub x} control, coal-based AR technologies are 50% less expansive than SCR for the same level of NO{sub x} control. The market for AR technologies is estimated to be above $110 million.

Impacts of acid gases on mercury oxidation across SCR catalyst

International Nuclear Information System (INIS)

Zhuang, Ye; Laumb, Jason; Liggett, Richard; Holmes, Mike; Pavlish, John

2007-01-01

A series of bench-scale experiments were completed to evaluate acid gases of HCl, SO 2 , and SO 3 on mercury oxidation across a commercial selective catalytic reduction (SCR) catalyst. The SCR catalyst was placed in a simulated flue gas stream containing O 2 , CO 2 , H 2 O, NO, NO 2 , and NH 3 , and N 2 . HCl, SO 2 , and SO 3 were added to the gas stream either separately or in combination to investigate their interactions with mercury over the SCR catalyst. The compositions of the simulated flue gas represent a medium-sulfur and low- to medium-chlorine coal that could represent either bituminous or subbituminous. The experimental data indicated that 5-50 ppm HCl in flue gas enhanced mercury oxidation within the SCR catalyst, possibly because of the reactive chlorine species formed through catalytic reactions. An addition of 5 ppm HCl in the simulated flue gas resulted in mercury oxidation of 45% across the SCR compared to only 4% mercury oxidation when 1 ppm HCl is in the flue gas. As HCl concentration increased to 50 ppm, 63% of Hg oxidation was reached. SO 2 and SO 3 showed a mitigating effect on mercury chlorination to some degree, depending on the concentrations of SO 2 and SO 3 , by competing against HCl for SCR adsorption sites. High levels of acid gases of HCl (50 ppm), SO 2 (2000 ppm), and SO 3 (50 ppm) in the flue gas deteriorate mercury adsorption on the SCR catalyst. (author)

Environmental impact of the nox and results in Mexico of the technologies for its control; Impacto ambiental de los NOx y resultados en Mexico de tecnologias de control

Energy Technology Data Exchange (ETDEWEB)

Ribera Flores, Marco Antonio [Nissan Mexicana S. A. de C. V. Cuernavaca (Mexico)

1994-12-31

This paper presents the experience gained in the project development for the installation of three burners for industrial boilers with low nitrogen oxides emission technology. The paper begins with a short reference to the effects on the environment, derived from the generation of these gases in combustion equipment and the reasons why this thermal NOx and the associated NOx are generated. A revision is made of the existing regulations to limit the emissions of these pollutants in industrial equipment in different countries, including Mexico. Mention is made of the existing control technologies and in particular indicating the emission reduction method determined for the burners in functional tests, using propane gas and diesel, before and after installing the control technology, to demonstrate the important reductions obtained. The other results such as the thermal efficiency are also plotted as well as other important pollutant emissions such as CO and CO{sub 2} for the observation of their behavior. [Espanol] El presente trabajo expone la experiencia obtenida en el desarrollo del proyecto de instalacion de tres quemadores para calderas industriales con tecnologia de baja emision de oxidos de nitrogeno. Se inicia haciendo una breve mencion de las repercusiones al medio ambiente que se derivan de la generacion de estos gases en equipos de combustion y las razones por las cuales se generan los NOx termicos y los NOx asociados a los combustibles. Se hace una revision sobre las regulaciones existentes para limitar las emisiones de estos contaminantes en equipos industriales en diferentes paises incluyendo a Mexico. Se mencionan las tecnologias de control existentes y en particular indicando el metodo de reduccion de emisiones determinadas para los quemadores en pruebas funcionales utilizando como combustibles gas propano y diesel antes y despues de instalar la tecnologia de control para demostrar las fuertes reducciones obtenidas, se grafican tambien otros resultados

Signal Control for Reducing Vehicle NOx and CO2 Emissions Based on Prediction of Arrival Traffic Flows at Intersections

Science.gov (United States)

Oda, Toshihiko

Nitrogen oxide (NOx) and carbon dioxide (CO2) emissions from vehicles have been increasing every year because of the growing number of vehicles, and they cause serious environmental problems such as air pollution and global warming. To alleviate these problems, this paper proposes a new traffic signal control method for reducing vehicle NOx and CO2 emissions on arterial roads. To this end, we first model the amount of vehicle emissions as a function of the traffic delay and the number of stops at intersections. This step is necessary because it is difficult to obtain the amount of emissions directly using traffic control systems. Second, we introduce a signal control model in which the control parameters are continuously updated on the basis of predictions of arrival traffic flows at intersections. The signal timings are calculated in such a manner so as to minimize the weighted sum of the two emissions, which depend on the traffic flow. To evaluate the validity of this method, simulation experiments are carried out on an arterial road. The experiments show that the proposed method significantly outperforms existing methods in reducing both the emissions and travel time.

A control-oriented real-time semi-empirical model for the prediction of NOx emissions in diesel engines

International Nuclear Information System (INIS)

D’Ambrosio, Stefano; Finesso, Roberto; Fu, Lezhong; Mittica, Antonio; Spessa, Ezio

2014-01-01

Highlights: • New semi-empirical correlation to predict NOx emissions in diesel engines. • Based on a real-time three-zone diagnostic combustion model. • The model is of fast application, and is therefore suitable for control-oriented applications. - Abstract: The present work describes the development of a fast control-oriented semi-empirical model that is capable of predicting NOx emissions in diesel engines under steady state and transient conditions. The model takes into account the maximum in-cylinder burned gas temperature of the main injection, the ambient gas-to-fuel ratio, the mass of injected fuel, the engine speed and the injection pressure. The evaluation of the temperature of the burned gas is based on a three-zone real-time diagnostic thermodynamic model that has recently been developed by the authors. Two correlations have also been developed in the present study, in order to evaluate the maximum burned gas temperature during the main combustion phase (derived from the three-zone diagnostic model) on the basis of significant engine parameters. The model has been tuned and applied to two diesel engines that feature different injection systems of the indirect acting piezoelectric, direct acting piezoelectric and solenoid type, respectively, over a wide range of steady-state operating conditions. The model has also been validated in transient operation conditions, over the urban and extra-urban phases of an NEDC. It has been shown that the proposed approach is capable of improving the predictive capability of NOx emissions, compared to previous approaches, and is characterized by a very low computational effort, as it is based on a single-equation correlation. It is therefore suitable for real-time applications, and could also be integrated in the engine control unit for closed-loop or feed-forward control tasks

Simultaneous NOx and hydrocarbon emissions control for lean-burn engines using low-temperature solid oxide fuel cell at open circuit.

Science.gov (United States)

Huang, Ta-Jen; Hsu, Sheng-Hsiang; Wu, Chung-Ying

2012-02-21

The high fuel efficiency of lean-burn engines is associated with high temperature and excess oxygen during combustion and thus is associated with high-concentration NO(x) emission. This work reveals that very high concentration of NO(x) in the exhaust can be reduced and hydrocarbons (HCs) can be simultaneously oxidized using a low-temperature solid oxide fuel cell (SOFC). An SOFC unit is constructed with Ni-YSZ as the anode, YSZ as the electrolyte, and La(0.6)Sr(0.4)CoO(3) (LSC)-Ce(0.9)Gd(0.1)O(1.95) as the cathode, with or without adding vanadium to LSC. SOFC operation at 450 °C and open circuit can effectively treat NO(x) over the cathode at a very high concentration in the simulated exhaust. Higher NO(x) concentration up to 5000 ppm can result in a larger NO(x) to N(2) rate. Moreover, a higher oxygen concentration promotes NO conversion. Complete oxidation of HCs can be achieved by adding silver to the LSC current collecting layer. The SOFC-based emissions control system can treat NO(x) and HCs simultaneously, and can be operated without consuming the anode fuel (a reductant) at near the engine exhaust temperature to eliminate the need for reductant refilling and extra heating.

System and method for selective catalytic reduction of nitrogen oxides in combustion exhaust gases

Science.gov (United States)

Sobolevskiy, Anatoly; Rossin, Joseph A

2014-04-08

A multi-stage selective catalytic reduction (SCR) unit (32) provides efficient reduction of NOx and other pollutants from about 50-550.degree. C. in a power plant (19). Hydrogen (24) and ammonia (29) are variably supplied to the SCR unit depending on temperature. An upstream portion (34) of the SCR unit catalyzes NOx+NH.sub.3 reactions above about 200.degree. C. A downstream portion (36) catalyzes NOx+H.sub.2 reactions below about 260.degree. C., and catalyzes oxidation of NH.sub.3, CO, and VOCs with oxygen in the exhaust above about 200.degree. C., efficiently removing NOx and other pollutants over a range of conditions with low slippage of NH.sub.3. An ammonia synthesis unit (28) may be connected to the SCR unit to provide NH.sub.3 as needed, avoiding transport and storage of ammonia or urea at the site. A carbonaceous gasification plant (18) on site may supply hydrogen and nitrogen to the ammonia synthesis unit, and hydrogen to the SCR unit.

NOx from lightning: 1. Global distribution based on lightning physics

Science.gov (United States)

Price, Colin; Penner, Joyce; Prather, Michael

1997-03-01

This paper begins a study on the role of lightning in maintaining the global distribution of nitrogen oxides (NOx) in the troposphere. It presents the first global and seasonal distributions of lightning-produced NOx (LNOx) based on the observed distribution of electrical storms and the physical properties of lightning strokes. We derive a global rate for cloud-to-ground (CG) flashes of 20-30 flashes/s with a mean energy per flash of 6.7×109 J. Intracloud (IC) flashes are more frequent, 50-70 flashes/s but have 10% of the energy of CG strokes and, consequently, produce significantly less NOx. It appears to us that the majority of previous studies have mistakenly assumed that all lightning flashes produce the same amount of NOx, thus overestimating the NOx production by a factor of 3. On the other hand, we feel these same studies have underestimated the energy released in CG flashes, resulting in two negating assumptions. For CG energies we adopt a production rate of 10×1016 molecules NO/J based on the current literature. Using a method to simulate global lightning frequencies from satellite-observed cloud data, we have calculated the LNOx on various spatial (regional, zonal, meridional, and global) and temporal scales (daily, monthly, seasonal, and interannual). Regionally, the production of LNOx is concentrated over tropical continental regions, predominantly in the summer hemisphere. The annual mean production rate is calculated to be 12.2 Tg N/yr, and we believe it extremely unlikely that this number is less than 5 or more than 20 Tg N/yr. Although most of LNOx, is produced in the lowest 5 km by CG lightning, convective mixing in the thunderstorms is likely to deposit large amounts of NOx, in the upper troposphere where it is important in ozone production. On an annual basis, 64% of the LNOx, is produced in the northern hemisphere, implying that the northern hemisphere should have natural ozone levels as much as 2 times greater than the southern hemisphere

Low cost SCR lamp driver indicates contents of digital computer registers

Science.gov (United States)

Cliff, R. A.

1967-01-01

Silicon Controlled Rectifier /SCR/ lamp driver is adapted for use in integrated circuit digital computers where it indicates the contents of the various registers. The threshold voltage at which visual indication begins is very sharply defined and can be adjusted to suit particular system requirements.

System analysis regarding NO{sub x} reduction with combined SNCR/SCR; Systemstudie avseende kombinerad NO{sub x}-reducering med SNCR/SCR

Energy Technology Data Exchange (ETDEWEB)

Niemann, Therese; Henningsson, Claes [S.E.P. Scandinavian Energy Project AB, Stockholm (Sweden); Andersson, Christer [Vattenfall Utveckling AB, Stockholm (Sweden)

2000-06-01

Systems with combined SNCR/SCR on biomass fired CFB:s have been focused on lately since they are regarded as very load flexible. Furthermore, synergy effects between the two parts are supposed to result in better performance for the combined system than for the two systems separately. The aim of this study is to investigate whether the combined SNCR/SCR matches the outlined expectations above. The plant chosen for the measurements was Brista Kraft AB. This particular plant is equipped with a CFB boiler of 122 MW{sub th}, which in turn is equipped with the deNO{sub x} system mentioned above. The measurements are made by a 'concentration gradient measurement system', developed by Vattenfall. Consequently, the study indicates that it is very useful to add a catalyst to the SNCR system, both from an environmental- and an economical point of view. However, since the full scale data for the SCR alone is missing, the results for SCR compared with combined SNCR/SCR is harder to decide. Simulations indicate that both systems produces the same emission levels, although, the SCR system may be a bit more cost effective in the long run. The synergy effect between the systems in combination is obvious. Predominantly because the NO{sub x} reduction efficiency in the SNCR zone can be increased (in this case about 10-12%) since a higher amount of ammonia can be accepted downstream of the SNCR zone. Combined systems will achieve a comparable good load independence. The reduction in the SNCR will decrease at lower loads, simultaneously as the reduction in the SCR increases. Thus, the total reduction efficiency will almost be independent of the load. In the project investigations have been made to figure out if two points injection in SNCR give more or less mol distribution of NH{sub 3}/NO quota over the catalyst crosses sectional area. The measurements indicates that two point injection may cause a more uneven distribution of stoichiometries. However, the results seems to

Study for a stress joint at the top of a SCR (Steel Catenary Risers); Estudo de 'stress joints' para o topo de um SCR (Steel Catenary Risers)

Energy Technology Data Exchange (ETDEWEB)

Siqueira, Elizabeth Frauches Netto; Andrade, Edmundo Queiroz de [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

2008-07-01

Steel Catenary Risers, SCRs, need a top connection that bears the force transmitted to the platform. Essentially, two types of connections exist on the market: flex joint and stress joint (SJ). PETROBRAS has a SCR with top connection of flex joint type installed on one of its platforms; however, the company has been studying SJ as an option out of SCR top connection. A stress joint is a monolithic structure and can be inspected during manufacture and service, without so many difficult. They are metal structures composed of a uniform bore inserted in a tapered wall that increases gradually to support the force coming from the riser. The objective of this paper is to present a SJ sensitivity study for a production SCR supposedly hardwired to a unit of production of the semi-submersible type. The data used is based on real SCR data. For this study, global and local analyses were conducted for some models of stress joints, varying some parameters such as material and dimensions, allowing for the verification of some of the critical points of this type of connection. The results obtained will be shown in graphs and tensions maps to illustrate comparatively the critical points of the models analyzed. (author)

Simultaneous removal of NO and Hg{sup 0} over Ce-Cu modified V{sub 2}O{sub 5}/TiO{sub 2} based commercial SCR catalysts

Energy Technology Data Exchange (ETDEWEB)

Chi, Guilong [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); College of Environmental Science & Engineering, Nankai University, Tianjin 300350 (China); Shen, Boxiong, E-mail: shenbx@nankai.edu.cn [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); Yu, Ranran [School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401 (China); He, Chuan; Zhang, Xiao [College of Environmental Science & Engineering, Nankai University, Tianjin 300350 (China)

2017-05-15

Highlights: • Simultaneous removal of NO and Hg{sup 0} over the novel modified commercial SCR catalysts. • 7% Ce-1% Cu/SCR catalyst exhibited excellent activity of NO conversion and Hg{sup 0} oxidation. • 7% Ce-1% Cu/SCR catalyst showed higher resistance to SO{sub 2} and H{sub 2}O than other catalysts. • The synergistic interaction between Ce and Cu in the catalyst improved the activity greatly. - Abstract: A series of novel Ce-Cu modified V{sub 2}O{sub 5}/TiO{sub 2} based commercial SCR catalysts were prepared via ultrasonic-assisted impregnation method for simultaneous removal of NO and elemental mercury (Hg{sup 0}). Nitrogen adsorption, X-ray diffraction (XRD), temperature programmed reduction of H{sub 2} (H{sub 2}-TPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. 7% Ce-1% Cu/SCR catalyst exhibited the highest NO conversion efficiency (>97%) at 200–400 °C, as well as the best Hg{sup 0} oxidation activity (>75%) at 150–350 °C among all the catalysts. The XPS and H{sub 2}-TPR results indicated that 7% Ce-1% Cu/SCR possess abundant chemisorbed oxygen and good redox ability, which was due to the strong synergy between Ce and Cu in the catalyst. The existence of the redox cycle of Ce{sup 4+} + Cu{sup 1+} ↔ Ce{sup 3+} + Cu{sup 2+} could greatly improve the catalytic activity. 7% Ce-1% Cu/SCR showed higher resistance to SO{sub 2} and H{sub 2}O than other catalysts. NO has a promoting effect on Hg{sup 0} oxidation. The Hg{sup 0} oxidation activity was inhibited by the injection of NH{sub 3}, which was due to the competitive adsorption and oxidized mercury could be reduced by ammonia at temperatures greater than 325 °C. Therefore, Hg{sup 0} oxidation could easily occurred at the outlet of SCR catalyst layer due to the consumption of NH{sub 3}.

Equivalent Consumption Minimization Strategy for the Control of Real Driving NOx Emissions of a Diesel Hybrid Electric Vehicle

Directory of Open Access Journals (Sweden)

Tobias Nüesch

2014-05-01

Full Text Available Motivated by the fact that the real driving NOx emissions (RDE of conventional diesel vehicles can exceed the legislation norms by far, a concept for the control of RDE with a diesel parallel hybrid electric vehicle (HEV is proposed. By extending the well-known equivalent consumption minimization strategy (ECMS, the power split degree of freedom is used to control the NOx emissions and the battery state of charge (SOC simultaneously. Through an appropriate formulation of the problem, the feedback control is shown to be separable into two dependent PI controllers. By hardware-in-the-loop (HIL experiments, as well as by simulations, the proposed method is shown to minimize the fuel consumption while tracking a given reference trajectory for both the NOx emissions and the battery SOC.

Vanadia supported on zeolites for SCR of NO by ammonia

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Riisager, Anders; Fehrmann, Rasmus

2010-01-01

, acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali-containing flue gases from, e.g. biomass fired...

Functional characterization of sucrose phosphorylase and scrR, a regulator of sucrose metabolism in Lactobacillus reuteri.

Science.gov (United States)

Teixeira, Januana S; Abdi, Reihaneh; Su, Marcia Shu-Wei; Schwab, Clarissa; Gänzle, Michael G

2013-12-01

Lactobacillus reuteri harbours alternative enzymes for sucrose metabolism, sucrose phosphorylase, fructansucrases, and glucansucrases. Sucrose phosphorylase and fructansucrases additionally contribute to raffinose metabolism. Glucansucrases and fructansucrases produce exopolysaccharides as alternative to sucrose hydrolysis. L. reuteri LTH5448 expresses a levansucrase (ftfA) and sucrose phosphorylase (scrP), both are inducible by sucrose. This study determined the contribution of scrP to sucrose and raffinose metabolism in L. reuteri LTH5448, and elucidated the role of scrR in regulation sucrose metabolism. Disruption of scrP and scrR was achieved by double crossover mutagenesis. L. reuteri LTH5448, LTH5448ΔscrP and LTH5448ΔscrR were characterized with respect to growth and metabolite formation with glucose, sucrose, or raffinose as sole carbon source. Inactivation of scrR led to constitutive transcription of scrP and ftfA, demonstrating that scrR is negative regulator. L. reuteri LTH5448 and the LTH5448ΔscrP or LTH5448ΔscrR mutant strains did not differ with respect to glucose, sucrose or raffinose utilization. However, L. reuteri LTH5448ΔscrP produced more levan, indicating that the lack of sucrose phosphorylase is compensated by an increased metabolic flux through levansucrase. In conclusion, the presence of alternate pathways for sucrose and raffinose metabolism and their regulation indicate that these substrates, which are abundant in plants, are preferred carbohydrate sources for L. reuteri. Copyright © 2013 Elsevier Ltd. All rights reserved.

Load-Independent Harmonic Mitigation in SCR-Fed Three-Phase Multiple Adjustable Speed Drive Systems with Deliberately Dispatched Firing Angles

DEFF Research Database (Denmark)

Yang, Yongheng; Davari, Pooya; Blaabjerg, Frede

2018-01-01

Adjustable speed drives (ASD) are widely used in industry for energy savings, where low-cost diode rectifiers are still employed as the front-ends, also for simplicity in control and reliability in operation. However, significant harmonics appear at the grid, which should be tackled according...... a harmonic mitigation strategy for multiple ASD systems, where silicon-controlled rectifiers (SCR) with boost converters in the dc-link have been adopted to increase the harmonic-current controllability. More specific, the SCR firing angles are deliberately dispatched among the drive units, which results...

Graphene and g-C3N4 based photocatalysts for NOx removal: A review

Science.gov (United States)

Nikokavoura, Aspasia; Trapalis, Christos

2018-02-01

NOx liberated into atmosphere from automobile exhausts and fossil fuel combustion, comprise the major air pollutants. They are responsible for serious environmental problems such as acid rain, ozone accumulation, haze and photochemical smog. Besides they contribute to the deterioration of human health by causing decrease of the lung function and respiratory problems. The application of photocatalytic methods in order to mitigate the presence of NOx in the atmosphere is preferable as they are environmentally friendly, mild and low cost. Therefore, in this review, the photocatalytic activity of g-C3N4 and graphene based composites towards NOx removal was discussed. NOx oxidation to non volatile nitrates on the surface of graphene and g-C3N4 based photocatalysts has attracted much interest during the last years due to their structures with unique features such as large specific surface area, thermal and chemical stability and enhanced visible light utilization. The formation of 2D-2D intimate heterojunctions between graphene or g-C3N4 and other components ensures the enhanced charge transfer, lifetime of electron/hole pairs and thus photocatalytic activity. The increased visible light harvesting also contributes to their usefulness as effective photocatalytic materials. In the present work, the advantages of these novel photocatalysts and the differences/similarities between them were exhaustively highlighted. The role of graphene as catalyst promoter, electron reservoir, support and photosensitizer in its photocatalytic composites was emphasized. The effect of g-C3N4 doping and copolymerization with metals/semiconductors on its photocatalytic activity towards NOx oxidation was thoroughly discussed. Besides, the preparation methods, photocatalytic efficiencies, type of irradiation, utilization of appropriate cocatalysts, and reaction mechanisms during the photocatalytic NOx removal by graphene and g-C3N4 composies, were summarized. It was demonstrated that in the vast

An SCR inverter for electric vehicles

Science.gov (United States)

Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.

1980-01-01

An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.

Simulation and Optimization of SCR System for Direct-injection Diesel Engine

Directory of Open Access Journals (Sweden)

Guanqiang Ruan

2014-11-01

Full Text Available The turbo diesel SCR system has been researched and analyzed in this paper. By using software of CATIA, three-dimensional physical model of SCR system has been established, and with software of AVL-FIRE, the boundary conditions have been set, simulated and optimized. In the process of SCR system optimizing, it mainly optimized the pray angle. Compare the effects of processing NO to obtain batter optimization results. At last the optimization results are compared by bench test, and the experimental results are quite consistent with simulation.

The effect of coal-fired power-plant SO2 and NOx control technologies on aerosol nucleation in the source plumes

Directory of Open Access Journals (Sweden)

E. M. Knipping

2012-12-01

Full Text Available Nucleation in coal-fired power-plant plumes can greatly contribute to particle number concentrations near source regions. The changing emissions rates of SO2 and NOx due to pollution-control technologies over recent decades may have had a significant effect on aerosol formation and growth in the plumes with ultimate implications for climate and human health. We use the System for Atmospheric Modeling (SAM large-eddy simulation model with the TwO-Moment Aerosol Sectional (TOMAS microphysics algorithm to model the nucleation in plumes of coal-fired plants. We test a range of cases with varying emissions to simulate the implementation of emissions-control technologies between 1997 and 2010. We start by simulating the W. A. Parish power plant (near Houston, TX during this time period, when NOx emissions were reduced by ~90% and SO2 emissions decreased by ~30%. Increases in plume OH (due to the reduced NOx produced enhanced SO2 oxidation and an order-of-magnitude increase in particle nucleation in the plume despite the reduction in SO2 emissions. These results suggest that NOx emissions could strongly regulate particle nucleation and growth in power-plant plumes. Next, we test a range of cases with varying emissions to simulate the implementation of SO2 and NOx emissions-control technologies. Particle formation generally increases with SO2 emission, while NOx shows two different regimes: increasing particle formation with increasing NOx under low-NOx emissions and decreasing particle formation with increasing NOx under high-NOx emissions. Next, we compare model results with airborne measurements made in the W. A. Parish power-plant plume in 2000 and 2006, confirming the importance of NOx emissions on new particle formation and highlighting the substantial effect of background aerosol loadings on this process (the more polluted background of the 2006 case caused more than an order-of-magnitude reduction in particle formation in the plume compared to

New fuel air control strategy for reducing NOx emissions from corner-fired utility boilers at medium-low loads

DEFF Research Database (Denmark)

Zhao, Sinan; Fang, Qingyan; Yin, Chungen

2017-01-01

Due to the rapidly growing renewable power, the fossil fuel power plants have to be increasingly operated under large and rapid load change conditions, which can induce various challenges. This work aims to reduce NOx emissions of large-scale corner-fired boilers operated at medium–low loads....... The combustion characteristics and NOx emissions from a 1000 MWe corner-fired tower boiler under different loads are investigated experimentally and numerically. A new control strategy for the annular fuel air is proposed and implemented in the boiler, in which the secondary air admitted to the furnace through...... the air annulus around each coal nozzle tip is controlled by the boiler load, instead of being controlled by the output of the connected mill as commonly used in this kind of power plant. Both the experimental and simulation results show that the new control strategy reduces NOx emissions at the entrance...

Demonstration of Selective Catalytic Reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers. Technical progress report, first and second quarters 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

The objective of this project is to demonstrate and evaluate commercially available Selective Catalytic Reduction (SCR) catalysts from U.S., Japanese and European catalyst suppliers on a high-sulfur U.S. coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO{sub x}) control technology that involve injecting ammonia into the flue gas generated from coal combustion in a boiler. The flue gas containing ammonia is then passed through a reactor that contains a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO{sub x} to form nitrogen and water vapor. Although SCR is widely practiced in Japan and Europe on gas-, oil-, and low-sulfur coal-fired boilers, there are several technical uncertainties associated with applying SCR to U.S. coals. These uncertainties include: (1) potential catalyst deactivation due to poisoning by trace metal species present in U.S. coals that are not present in other fuels; (2) performance of the technology and effects on the balance-of-plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}; and (3) performance of a wide variety of SCR catalyst compositions, geometries and methods of manufacture under typical high-sulfur coal-fired utility operating conditions. These uncertainties are being explored by operating a series of small-scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur U.S. coal. The project is being conducted in the following three phases: permitting, environmental monitoring plan and preliminary engineering; detailed design engineering and construction; and operation, testing, disposition and final report. The project was in the operation and testing phase during this reporting period. Accomplishments for this period are described.

Air pollution control technologies and their interactions

Energy Technology Data Exchange (ETDEWEB)

Nalbandian, H. [IEA Clean Coal Centre, London (United Kingdom)

2004-11-01

A large number of coal-fired power stations have been fitted/retrofitted with dedicated air pollutant control technologies. Experience shows that these technologies can have complex interactions and can impact each other as well as balance of plant, positively and/or negatively. Particulate matter (PM) is usually captured with electrostatic precipitators (ESPs) and fabric filters (FF). These technologies are efficient and reliable but their performance may be affected by modifying operating conditions and introducing primary measures for NOx reduction. Flue gas desulphurisation (FGD) systems for SO{sub 2} control have been installed in many facilities with the most popular technology being the wet limestone/gypsum scrubber. FGD use can decrease particulate matter and mercury emissions which is a major issue in the USA, cause an increase in carbon dioxide emissions, and in solids by-product. Primary measures such as low NOx burners (LNBs) and overfire air (OFA) minimise NOx formation but can increase carbon in ash (CIA) which can cause problems with fly ash sales but may also improve mercury capture. Reducing NOx emissions with selective catalytic reduction (SCR) can result in a decrease in particulate matter, an increase in SO{sub 3} emissions and trace increase in NH{sub 3}. This can cause fouling and loss of performance of the air preheater, due to the formation of ammonium sulphates. One way of alleviating this is improved soot-blowing and other cleaning capabilities. This report studies these and other interactions between existing air pollution control technologies in pulverised coal fired power plants. 249 refs., 13 figs., 18 tabs.

Effects of Particle Filters and Selective Catalytic Reduction on In-Use Heavy-Duty Diesel Truck Emissions

Science.gov (United States)

Preble, C.; Cados, T.; Harley, R.; Kirchstetter, T.

2016-12-01

Heavy-duty diesel trucks (HDDT) are a major source of nitrogen oxides (NOx) and black carbon (BC) in urban environments, contributing to persistent ozone and particulate matter air quality problems. Diesel particle filters (DPFs) and selective catalytic reduction (SCR) systems that target PM and NOx emissions, respectively, have recently become standard equipment on new HDDT. DPFs can also be installed on older engines as a retrofit device. Previous work has shown that DPF and SCR systems can reduce NOx and BC emissions by up to 70% and 90%, respectively, compared to modern trucks without these after-treatment controls (Preble et al., ES&T 2015). DPFs can have the undesirable side-effect of increasing ultrafine particle (UFP) and nitrogen dioxide (NO2) emissions. While SCR systems can partially mitigate DPF-related NO2 increases, these systems can emit nitrous oxide (N2O), a potent greenhouse gas. We report new results from a study of HDDT emissions conducted in fall 2015 at the Port of Oakland and Caldecott Tunnel in California's San Francisco Bay Area. We report pollutant emission factors (g kg-1) for emitted NOx, NO2, BC, PM2.5, UFP, and N2O on a truck-by-truck basis. Using a roadside license plate recognition system, we categorize each truck by its engine model year and installed after-treatment controls. From this, we develop emissions profiles for trucks with and without DPF and SCR. We evaluate the effectiveness of these devices as a function of their age to determine whether degradation is an issue. We also compare the emission profiles of trucks traveling at low speeds along a level, arterial road en route to the port and at high speeds up a 4% grade highway approaching the tunnel. Given the climate impacts of BC and N2O, we also examine the global warming potential of emissions from trucks with and without DPF and SCR.

SCR-1: Design and construction of a small modular stellarator for magnetic confinement of plasma

International Nuclear Information System (INIS)

Barillas, L; Vargas, V I; Alpizar, A; Asenjo, J; Carranza, J M; Cerdas, F; Gutiérrez, R; Monge, J I; Mora, J; Morera, J; Peraza, H; Rojas, C; Rozen, D; Saenz, F; Sánchez, G; Sandoval, M; Trimiño, H; Umaña, J; Villegas, L F; Queral, V

2014-01-01

This paper describes briefly the design and construction of a small modular stellarator for magnetic confinement of plasma, called Stellarator of Costa Rica 1, or SCR-1; developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica, PlasmaTEC. The SCR-1 is based on the small Spanish stellarator UST 1 , created by the engineer Vicente Queral. The SCR-1 will employ stainless steel torus-shaped vacuum vessel with a major radius of 460.33 mm and a cross section radius of 110.25 mm. A typical SCR-1 plasma will have an average radius 42.2 mm and a volume of 8 liters (0.01 m 3 ), and an aspect ratio of 5.7. The magnetic resonant field will be 0.0878 T, and a period of 2 (m=2) with a rotational transform of 0.3. The magnetic field will be provided by 12 modular coils, with 8 turns each, with an electrical current of 8704 A per coil (1088 A per turn of each coil). This current will be fed by a bank of cell batteries. The plasma will be heated by ECRH with magnetrons of a total power of 5 kW, in the first harmonic at 2.45 GHz. The expected electron temperature and density are 15 eV and 10 17 m −3 respectively with an estimated confinement time of 7.30 x 10 −4 ms. The initial diagnostics on the SCR-1 will consist of a Langmuir probe, a heterodyne microwave interferometer, and a field mapping system. The first plasma of the SCR-1 is expected at the end of 2011.

Deficiency of NOX1 or NOX4 Prevents Liver Inflammation and Fibrosis in Mice through Inhibition of Hepatic Stellate Cell Activation.

Directory of Open Access Journals (Sweden)

Tian Lan

Full Text Available Reactive oxygen species (ROS produced by nicotinamide adenine dinucleotide phosphate oxidase (NOX play a key role in liver injury and fibrosis. Previous studies demonstrated that GKT137831, a dual NOX1/4 inhibitor, attenuated liver fibrosis in mice as well as pro-fibrotic genes in hepatic stellate cells (HSCs as well as hepatocyte apoptosis. The effect of NOX1 and NOX4 deficiency in liver fibrosis is unclear, and has never been directly compared. HSCs are the primary myofibroblasts in the pathogenesis of liver fibrosis. Therefore, we aimed to determine the role of NOX1 and NOX4 in liver fibrosis, and investigated whether NOX1 and NOX4 signaling mediates liver fibrosis by regulating HSC activation. Mice were treated with carbon tetrachloride (CCl4 to induce liver fibrosis. Deficiency of either NOX1 or NOX4 attenuates liver injury, inflammation, and fibrosis after CCl4 compared to wild-type mice. NOX1 or NOX4 deficiency reduced lipid peroxidation and ROS production in mice with liver fibrosis. NOX1 and NOX4 deficiency are approximately equally effective in preventing liver injury in the mice. The NOX1/4 dual inhibitor GKT137831 suppressed ROS production as well as inflammatory and proliferative genes induced by lipopolysaccharide (LPS, platelet-derived growth factor (PDGF, or sonic hedgehog (Shh in primary mouse HSCs. Furthermore, the mRNAs of proliferative and pro-fibrotic genes were downregulated in NOX1 and NOX4 knock-out activated HSCs (cultured on plastic for 5 days. Finally, NOX1 and NOX4 protein levels were increased in human livers with cirrhosis compared with normal controls. Thus, NOX1 and NOX4 signaling mediates the pathogenesis of liver fibrosis, including the direct activation of HSC.

A study on synthetic method and material characteristics of magnesium ammine chloride as ammonia transport materials for solid SCR

Energy Technology Data Exchange (ETDEWEB)

Shin, Jong Kook; Yoon, Cheon Seog [Dept. of Mechanical Engineering, Hannam University, Daejeon (Korea, Republic of); Kim, Hong Suk [Engine Research Center, Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2015-11-15

Among various ammonium salts and metal ammine chlorides used as solid materials for the sources of ammonia with solid SCR for lean NOx reduction, magnesium ammine chloride was taken up for study in this paper because of its ease of handling and safety. Lab-scale synthetic method of magnesium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%). To understand material characteristics for lab-made magnesium ammine chloride, DA, IC, FT-IR, XRD and SDT analyses were performed using the published data available in literature. From the analytical results, the water content in the lab-made magnesium ammine chloride can be determined. A new test procedure for water removal was proposed, by which the adsorption rate of lab-made sample was found to be approximately 100%.

A study on synthetic method and material characteristics of magnesium ammine chloride as ammonia transport materials for solid SCR

International Nuclear Information System (INIS)

Shin, Jong Kook; Yoon, Cheon Seog; Kim, Hong Suk

2015-01-01

Among various ammonium salts and metal ammine chlorides used as solid materials for the sources of ammonia with solid SCR for lean NOx reduction, magnesium ammine chloride was taken up for study in this paper because of its ease of handling and safety. Lab-scale synthetic method of magnesium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%). To understand material characteristics for lab-made magnesium ammine chloride, DA, IC, FT-IR, XRD and SDT analyses were performed using the published data available in literature. From the analytical results, the water content in the lab-made magnesium ammine chloride can be determined. A new test procedure for water removal was proposed, by which the adsorption rate of lab-made sample was found to be approximately 100%

Silicon carbide based sensor system for minimized emissions in flue gases; Kiselkarbidbaserat sensorsystem foer minimering av emissioner i roekgaser

Energy Technology Data Exchange (ETDEWEB)

Lloyd Spetz, Anita; Bjorklund, Robert

2012-02-15

Control of the combustion process is necessary in order to operate boilers in an economic and environmentally acceptable manner. Large power plants can afford expensive measurement instruments to continuously monitor the composition of flue gas. Smaller facilities often lack complete gas analysis systems and it would be to their advantage to have access to inexpensive measurement equipment which could be installed at several points in the flue gas channel. Since oxygen concentration is such an important parameter for describing the combustion process the lambdasond is currently being used as an oxygen sensor in flue gas. It has the advantage of usage for more than 30 years in the automobile industry. Experience from that application has aided its introduction in the power industry. Conditions are not the same in the two branches but the lambdasond is an established technology, produced in large volume, widely available and inexpensive. Vehicle manufacturers continue to develop sensor technology and monitoring capabilities have been extended to CO, NOx and NH3. The latter is the result of SCR (selective catalytic reduction) of NOx by addition of NH3 (from urea), which has been introduced as an exhaust gas aftertreatment technology in diesel powered vehicles. The power industry can be expected to follow this trend by incorporating sensors for monitoring and control of SCR and SNCR (non-catalytic selective reduction) in flue gas applications. This report describes evaluation of silicon carbide based transistors, which have previously been studied in diesel exhaust gas and small boiler flue gas, for applications in larger power plants

Kinetic experiments and modeling of NO oxidation and SCR of NOx with decane over Cu- and Fe-MFI catalysts

Czech Academy of Sciences Publication Activity Database

Čapek, Libor; Vradman, L.; Sazama, Petr; Herskowitz, M.; Wichterlová, Blanka; Zukerman, R.; Brosius, R.; Martens, J. A.

2007-01-01

Roč. 70, 1-4 (2007), s. 53-57 ISSN 0926-3373 Grant - others:European Union(XE) GR5D-CT 2001-00595 Institutional research plan: CEZ:AV0Z40400503 Source of funding: O - operačné programy Keywords : NO oxidation * Nox reduction with hydrocarbons * heterogeneous kinetic s * iron zeolite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.651, year: 2007

Nitrogen oxides emissions from thermal power plants in china: current status and future predictions.

Science.gov (United States)

Tian, Hezhong; Liu, Kaiyun; Hao, Jiming; Wang, Yan; Gao, Jiajia; Qiu, Peipei; Zhu, Chuanyong

2013-10-01

Increasing emissions of nitrogen oxides (NOx) over the Chinese mainland have been of great concern due to their adverse impacts on regional air quality and public health. To explore and obtain the temporal and spatial characteristics of NOx emissions from thermal power plants in China, a unit-based method is developed. The method assesses NOx emissions based on detailed information on unit capacity, boiler and burner patterns, feed fuel types, emission control technologies, and geographical locations. The national total NOx emissions in 2010 are estimated at 7801.6 kt, of which 5495.8 kt is released from coal-fired power plant units of considerable size between 300 and 1000 MW. The top provincial emitter is Shandong where plants are densely concentrated. The average NOx-intensity is estimated at 2.28 g/kWh, markedly higher than that of developed countries, mainly owing to the inadequate application of high-efficiency denitrification devices such as selective catalytic reduction (SCR). Future NOx emissions are predicted by applying scenario analysis, indicating that a reduction of about 40% by the year 2020 can be achieved compared with emissions in 2010. These results suggest that NOx emissions from Chinese thermal power plants could be substantially mitigated within 10 years if reasonable control measures were implemented effectively.

Reducción catalítica selectiva de NOx usando nanopartículas de ferritas Cu1-XCoXFe2O4 como catalizador

Directory of Open Access Journals (Sweden)

Sarah Briceño1*

2009-12-01

Full Text Available Nanostructured catalysts AB2O4 spinel type oxides (A = Co and B = Cu were prepared by the sol-gel self-combustion method using citric acid as precursor. They were characterized by X-ray diffraction (XRD, Scanning Electron Microscopy (SEM, Transmission Electron Microscopy (TEM and Catalytic activity tests, which have proven to be effective for selective catalytic reduction of NOx using hydrocarbon as a reducing agent (SCR-HC in a temperature range 250 - 450 ° C, reaching up to 40% conversion of NO and 100% selectivity towards the formation of N2

40 CFR 96.142 - CAIR NOX allowance allocations.

Science.gov (United States)

2010-07-01

... the 3 highest amounts of the unit's adjusted control period heat input for 2000 through 2004, with the adjusted control period heat input for each year calculated as follows: (A) If the unit is coal-fired... CAIR NOX Allowance Allocations § 96.142 CAIR NOX allowance allocations. (a)(1) The baseline heat input...

Cloning and Characterization of ThSHRs and ThSCR Transcription Factors in Taxodium Hybrid 'Zhongshanshan 406'.

Science.gov (United States)

Wang, Zhiquan; Yin, Yunlong; Hua, Jianfeng; Fan, Wencai; Yu, Chaoguang; Xuan, Lei; Yu, Fangyuan

2017-07-20

Among the GRAS family of transcription factors, SHORT ROOT (SHR) and SCARECROW (SCR) are key regulators of the formation of root tissues. In this study, we isolated and characterized two genes encoding SHR proteins and one gene encoding an SCR protein: ThSHR1 (Accession Number MF045148), ThSHR2 (Accession Number MF045149) and ThSCR (Accession Number MF045152) in the adventitious roots of Taxodium hybrid 'Zhongshanshan'. Gene structure analysis indicated that ThSHR1 , ThSHR2 and ThSCR are all intron free. Multiple protein sequence alignments showed that each of the corresponding proteins, ThSHR1, ThSHR2 and ThSCR, contained five well-conserved domains: leucine heptad repeat I (LHRI), the VHIID motif, leucine heptad repeat II (LHR II), the PFYRE motif, and the SAW motif. The phylogenetic analysis indicated that ThSCR was positioned in the SCR clade with the SCR proteins from eight other species, while ThSHR1 and ThSHR2 were positioned in the SHR clade with the SHR proteins from six other species. Temporal expression patterns of these genes were profiled during the process of adventitious root development on stem cuttings. Whereas expression of both ThSHR2 and ThSCR increased up to primary root formation before declining, that of ThSHR1 increased steadily throughout adventitious root formation. Subcellular localization studies in transgenic poplar protoplasts revealed that ThSHR1, ThSHR2 and ThSCR were localized in the nucleus. Collectively, these results suggest that the three genes encode Taxodium GRAS family transcription factors, and the findings contribute to improving our understanding of the expression and function of SHR and SCR during adventitious root production, which may then be manipulated to achieve high rates of asexual propagation of valuable tree species.

Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

Energy Technology Data Exchange (ETDEWEB)

Nigel Clark; Gregory Thompson; Richard Atkinson; Richard Turton; Chamila Tissera; Emre Tatli; Andy Zimmerman

2005-12-28

review meeting at Argonne National Laboratories, in-cylinder pressure was measured to calculate engine indicated mean effective pressure (IMEP) changes due to NOx injections and EGR variations, and to observe conditions in the cylinder. The third experimental campaign gathered NOx decomposition data at 800, 1200 and 1800 rpm. EGR was added via an external loop, with EGR ranging from zero to the point of misfire. The air/fuel ratio was set at both stoichiometric and slightly rich conditions, and NOx decomposition rates were calculated for each set of runs. Modifications were made to the engine exhaust manifold to record individual exhaust temperatures. The three experimental campaigns have provided the data needed for a comprehensive model of NOx decomposition during the combustion process, and data have confirmed that there was no significant impact of injected NO on in-cylinder pressure. The NOx adsorption system provided by Sorbent Technologies Corp. (Twinsburg, OH), comprised a NOx adsorber, heat exchanger and a demister. These components were connected to the engine, and data were gathered to show both the adsorption of NOx from the engine, and desorption of NOx from the carbon-based sorbent material back into the engine intake, using a heated air stream. In order to quantify the NOx adsorption/desorption characteristics of the sorbent material, a bench top adsorption system was constructed and instrumented with thermocouples and the system output was fed into a NOx analyzer. The temperature of this apparatus was controlled while gathering data on the characteristics of the sorbent material. These data were required for development of a system model. Preliminary data were gathered in 2005, and will continue in early 2006. To assess the economic benefits of the proposed SNR technology the WVU research team has been joined in the last quarter by Dr Richard Turton (WVU-Chemical Engineering), who is modeling, sizing and costing the major components. The tasks will

Alloy SCR-3 resistant to stress corrosion cracking

International Nuclear Information System (INIS)

Kowaka, Masamichi; Fujikawa, Hisao; Kobayashi, Taiki

1977-01-01

Austenitic stainless steel is used widely because the corrosion resistance, workability and weldability are excellent, but the main fault is the occurrence of stress corrosion cracking in the environment containing chlorides. Inconel 600, most resistant to stress corrosion cracking, is not necessarily safe under some severe condition. In the heat-affected zone of SUS 304 tubes for BWRs, the cases of stress corrosion cracking have occurred. The conventional testing method of stress corrosion cracking using boiling magnesium chloride solution has been problematical because it is widely different from actual environment. The effects of alloying elements on stress corrosion cracking are remarkably different according to the environment. These effects were investigated systematically in high temperature, high pressure water, and as the result, Alloy SCR-3 with excellent stress corrosion cracking resistance was found. The physical constants and the mechanical properties of the SCR-3 are shown. The states of stress corrosion cracking in high temperature, high pressure water containing chlorides and pure water, polythionic acid, sodium phosphate solution and caustic soda of the SCR-3, SUS 304, Inconel 600 and Incoloy 800 are compared and reported. (Kako, I.)

A method of formal requirements analysis for NPP I and C systems based on object-oriented visual modeling with SCR

International Nuclear Information System (INIS)

Koo, S. R.; Seong, P. H.

1999-01-01

In this work, a formal requirements analysis method for Nuclear Power Plant (NPP) I and C systems is suggested. This method uses Unified Modeling Language (UML) for modeling systems visually and Software Cost Reduction (SCR) formalism for checking the system models. Since object-oriented method can analyze a document by the objects in a real system, UML models that use object-oriented method are useful for understanding problems and communicating with everyone involved in the project. In order to analyze the requirement more formally, SCR tabular notations is converted from UML models. To help flow-through from UML models to SCR specifications, additional syntactic extensions for UML notation and a converting procedure are defined. The combined method has been applied to Dynamic Safety System (DSS). From this application, three kinds of errors were detected in the existing DSS requirements

Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NOx reduction with NH3

Science.gov (United States)

Pourkhalil, Mahnaz; Moghaddam, Abdolsamad Zarringhalam; Rashidi, Alimorad; Towfighi, Jafar; Mortazavi, Yadollah

2013-08-01

Manganese oxide catalysts (MnOx) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by the incipient wetness impregnation method. These catalysts were characterized by N2 adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H2-temperature programmed reduction (H2-TPR) methods. The effects of reaction temperature, MnOx loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NOx with NH3. Under the reaction conditions of 200 °C, 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol%, GHSV = 30,000 h-1 and 12 wt% MnOx, NOx conversion and N2 selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO2 and 2.5 vol% H2O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.

Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself

Directory of Open Access Journals (Sweden)

Ralf Moos

2011-08-01

Full Text Available Recently, it has been shown that the degree of loading of several types of automotive exhaust aftertreatment devices can be directly monitored in situ and in a contactless way by a microwave-based method. The goal of this study was to clarify whether this method can also be applied to NOx storage and reduction catalysts (lean NOx traps in order to obtain further knowledge about the reactions occurring in the catalyst and to compare the results with those obtained by wirebound NOx loading sensors. It is shown that both methods are able to detect the different catalyst loading states. However, the sensitivity of the microwave-based method turned out to be small compared to that previously observed for other exhaust aftertreatment devices. This may limit the practical applicability of the microwave-based NOx loading detection in lean NOx traps.

Feasibility of plasma aftertreatment for simultaneous control of NOx and particulates

International Nuclear Information System (INIS)

Brusasco, R M; Merritt, B T; Penetrante, B; Pitz, W J; Vogtlin, G E

1999-01-01

Plasma reactors can be operated as a particulate trap or as a NOx converter. Particulate trapping in a plasma reactor can be accomplished by electrostatic precipitation. The soluble organic fraction of the trapped particulates can be utilized for the hydrocarbon-enhanced oxidation of NO to NO2 . The NO2 can then be used to non-thermally oxidize the carbon fraction of the particulates. The oxidation of the carbon fraction by NO2 can lead to reduction of NOx or backconversion of NO2 to NO. This paper examines the hydrocarbon and electrical energy density requirements in a plasma for maximum NOx conversion in both heavy-duty and light-duty diesel engine exhaust. The energy density required for complete oxidation of hydrocarbons is also examined and shown to be much greater than that required for maximum NOx conversion. The reaction of NO2 with carbon is shown to lead mainly to backconversion of NO2 to NO. These results suggest that the combination of the plasma with a catalyst will be required to reduce the NOx and oxidize the hydrocarbons. The plasma reactor can be operated occasionally in the arc mode to thermally oxidize the carbon fraction of the particulates

Parameter estimation and analysis of an automotive heavy-duty SCR catalyst model

DEFF Research Database (Denmark)

Åberg, Andreas; Widd, Anders; Abildskov, Jens

2017-01-01

A single channel model for a heavy-duty SCR catalyst was derived based on first principles. The model considered heat and mass transfer between the channel gas phase and the wash coat phase. The parameters of the kinetic model were estimated using bench-scale monolith isothermal data. Validation ...

Influence of reaction products of K-getter fuel additives on commercial vanadia-based SCR catalysts Part II. Simultaneous addition of KCl, Ca(OH)(2), H3PO4 and H2SO4 in a hot flue gas at a SCR pilot-scale setup

DEFF Research Database (Denmark)

Castellino, Francesco; Jensen, Anker Degn; Johnsson, Jan Erik

2009-01-01

A commercial V2O5-WO3-TiO2 corrugated-type SCR monolith has been exposed for 1000 h in a pilot-scale setup to a flue gas doped with KCl, Ca(OH)(2), H3PO4 and H2SO4 by spraying a water solution of the components into the hot flue gas. The mixture composition has been adjusted in order to have P...... surface and did not proceed at the fast rates known for KCl. This fact indicates that binding K in P-K-Ca compounds is an effective way to reduce the negative influence of alkali metals on the lifetime of the vanadia-based SCR catalysts. On the other hand, P-deposition was favoured by the formation...

Myeloid-specific deletion of NOX2 prevents the metabolic and neurologic consequences of high fat diet.

Directory of Open Access Journals (Sweden)

Jennifer K Pepping

Full Text Available High fat diet-induced obesity is associated with inflammatory and oxidative signaling in macrophages that likely participates in metabolic and physiologic impairment. One key factor that could drive pathologic changes in macrophages is the pro-inflammatory, pro-oxidant enzyme NADPH oxidase. However, NADPH oxidase is a pleiotropic enzyme with both pathologic and physiologic functions, ruling out indiscriminant NADPH oxidase inhibition as a viable therapy. To determine if targeted inhibition of monocyte/macrophage NADPH oxidase could mitigate obesity pathology, we generated mice that lack the NADPH oxidase catalytic subunit NOX2 in myeloid lineage cells. C57Bl/6 control (NOX2-FL and myeloid-deficient NOX2 (mNOX2-KO mice were given high fat diet for 16 weeks, and subject to comprehensive metabolic, behavioral, and biochemical analyses. Data show that mNOX2-KO mice had lower body weight, delayed adiposity, attenuated visceral inflammation, and decreased macrophage infiltration and cell injury in visceral adipose relative to control NOX2-FL mice. Moreover, the effects of high fat diet on glucose regulation and circulating lipids were attenuated in mNOX2-KO mice. Finally, memory was impaired and markers of brain injury increased in NOX2-FL, but not mNOX2-KO mice. Collectively, these data indicate that NOX2 signaling in macrophages participates in the pathogenesis of obesity, and reinforce a key role for macrophage inflammation in diet-induced metabolic and neurologic decline. Development of macrophage/immune-specific NOX-based therapies could thus potentially be used to preserve metabolic and neurologic function in the context of obesity.

Pilot test and optimization of plasma based deNOx

DEFF Research Database (Denmark)

Stamate, Eugen; Chen, Weifeng; Michelsen, Poul

. Experiments are in good agreement with numerical simulations. An optimized oxidation scheme for NOx reduction processes with time dependent combustion, such as the biomass power plants, was developed. Ozone production by micro-hollow and capillary discharges at atmospheric pressures was investigated......The NOx reduction of flue gas by plasma generated ozone was investigated in pilot test experiments at two industrial power plants running on natural gas (Ringsted) and biomass (Haslev). Reduction rates higher than 95% have been achieved for a molar ratio O3:NOx of 1.56. Fourier transform infrared...... and ultraviolet absorption spectroscopy were used for spatial measurements of stable molecules and radicals along the reduction reactor. Reactions of O3 injected in the flue gas in the reduction reactor were also modeled including the influence of the flue gas temperature, water droplets and SOx and HCl content...

Impacts of halogen additions on mercury oxidation, in a slipstream selective catalyst reduction (SCR), reactor when burning sub-bituminous coal.

Science.gov (United States)

Cao, Yan; Gao, Zhengyang; Zhu, Jiashun; Wang, Quanhai; Huang, Yaji; Chiu, Chengchung; Parker, Bruce; Chu, Paul; Pant, Wei-Ping

2008-01-01

This paper presents a comparison of impacts of halogen species on the elemental mercury (Hg(0)) oxidation in a real coal-derived flue gas atmosphere. It is reported there is a higher percentage of Hg(0) in the flue gas when burning sub-bituminous coal (herein Powder River Basin (PRB) coal) and lignite, even with the use of selective catalytic reduction (SCR). The higher Hg(0)concentration in the flue gas makes it difficult to use the wet-FGD process for the mercury emission control in coal-fired utility boilers. Investigation of enhanced Hg(0) oxidation by addition of hydrogen halogens (HF, HCl, HBr, and HI) was conducted in a slipstream reactor with and without SCR catalysts when burning PRB coal. Two commercial SCR catalysts were evaluated. SCR catalyst no. 1 showed higher efficiencies of both NO reduction and Hg(0) oxidation than those of SCR catalyst no. 2. NH3 addition seemed to inhibit the Hg(0) oxidation, which indicated competitive processes between NH3 reduction and Hg(0) oxidation on the surface of SCR catalysts. The hydrogen halogens, in the order of impact on Hg(0) oxidation, were HBr, HI, and HCl or HF. Addition of HBr at approximately 3 ppm could achieve 80% Hg(0) oxidation. Addition of HI at approximately 5 ppm could achieve 40% Hg(0) oxidation. In comparison to the empty reactor, 40% Hg(0) oxidation could be achieved when HCl addition was up to 300 ppm. The enhanced Hg(0) oxidation by addition of HBr and HI seemed not to be correlated to the catalytic effects by both evaluated SCR catalysts. The effectiveness of conversion of hydrogen halogens to halogen molecules or interhalogens seemed to be attributed to their impacts on Hg(0) oxidation.

Vanadia-based SCR Catalysts Supported on Tungstated and Sulfated Zirconia: Influence of Doping with Potassium

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Boghosian, Soghomon; Kustov, Arkadii

2007-01-01

A series of vanadium-based SCR catalysts supported on sulfated or tungstated ZrO2 were synthesized and characterized by means of N2-BET, XRD, NH3-TPD and in situ Raman spectroscopy. The effect of potassium doping on the properties of vanadia species is studied in detail. A number of catalyst...... and morphology, the surface composition and the molecular configuration of the dispersed vanadates. It was observed that poisoning with potassium had a negligible effect on the surface vanadate species (especially the V=O stretching frequency observed by in situ Raman spectroscopy) if supported on the sulfated...... the observed decrease in V=O stretching frequency and the higher proportion of dimers and higher polymers through coordination between K+ and two neighbouring V=O. The results suggest an increased resistance towards potassium doping for the vanadia-based catalysts supported on sulfated zirconia....

EMISSION REDUCTION FROM A DIESEL ENGINE FUELED BY CERIUM OXIDE NANO-ADDITIVES USING SCR WITH DIFFERENT METAL OXIDES COATED CATALYTIC CONVERTER

Directory of Open Access Journals (Sweden)

B. JOTHI THIRUMAL

2015-11-01

Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in nanoparticle form on the major physiochemical properties and the performance of diesel. The fuel is modified by dispersing the catalytic nanoparticle by ultrasonic agitation. The physiochemical properties of sole diesel fuel and modified fuel are tested with ASTM standard procedures. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Cerium oxide acts as an oxygen-donating catalyst and provides oxygen for the oxidation of CO during combustion. The active energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall which results in reduction in HC emission by 56.5%. Furthermore, a low-cost metal oxide coated SCR (selective catalyst reduction, using urea as a reducing agent, along with different types of CC (catalytic converter, has been implemented in the exhaust pipe to reduce NOx. It was observed that a reduction in NOx emission is 50–60%. The tests revealed that cerium oxide nanoparticles can be used as an additive in diesel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

TEST DESIGN FOR ENVIRONMENTAL TECHNOLOGY VERIFICATION (ETV) OF ADD-ON NOX CONTROL UTILIZING OZONE INJECTION

Science.gov (United States)

The paper discusses the test design for environmental technology verification (ETV) of add-0n nitrogen oxides (NOx) control utilizing ozone injection. (NOTE: ETV is an EPA-established program to enhance domestic and international market acceptance of new or improved commercially...

A rate based reactor model for BiodeNOx absorber units

NARCIS (Netherlands)

Winkelman, J. G. M.; Gambardella, F.; Heeres, H. J.

2007-01-01

The reactive absorption of NO in aqueous solutions of Fe-II(EDTA), resulting in the formation of a nitrosyl complex, Fe-II(EDTA)(NO), is a key step of the BiodeNOx process for the removal of NOx from industrial flue gas. Oxygen present in the flue gas will also absorb and oxidize Fe-II(EDTA). This

Electrochemical reduction of NOx

DEFF Research Database (Denmark)

Traulsen, Marie Lund

NO and NO2 (collectively referred to as NOx) are air pollutants, and the largest single contributor to NOx pollution is automotive exhaust. This study investigates electrochemical deNOx, a technology which aims to remove NOx from automotive diesel exhaust by electrochemical reduction of NOx to N2...... and O2. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNOx by addition of NOx storage compounds to the electrodes. Two different composite electrodes, La0.85Sr0.15MnO3-δ-Ce0.9Gd0.1O1.95 (LSM15-CGO10) and La0.85Sr0.15FeO3-δ-Ce0.9Gd0.1O......1.95 (LSF15-CGO10), have been investigated in combination with three different NOx storage compounds: BaO, K2O and MnOx. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy...

Innovative Clean Coal Technology (ICCT): Demonstration of selective catalytic reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers. Technical progress report, third and fourth quarters 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

The objective of this project is to demonstrate and evaluate commercially available selective catalytic reduction (SCR) catalysts from U.S., Japanese, and European catalyst suppliers on a high-sulfur U.S. Coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO{sub x}) control technology that involves injecting ammonia into the flue gas generated from coal combustion in an electric utility boiler. The flue gas containing ammonia is then passed through a reactor that contains a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO{sub x} to form nitrogen and water vapor. Although SCR is widely practiced in Japan and European gas-, oil-, and low-sulfur coal-fired boilers, there are several technical uncertainties associated with applying SCR to U.S. coals. These uncertainties include: (1) potential catalyst deactivation due to poisoning by trace metal species present in U.S. coals that are not present in other fuels; (2) performance of the technology and effects on the balance-of-plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}; performance of a wide variety of SCR catalyst compositions, geometries, and methods of manufacture under typical high-sulfur coal-fired utility operating conditions. These uncertainties are being explored by operating a series of small- scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur U.S. coal. The demonstration is being performed at Gulf Power Company`s Plant Crist Unit No. 5 (75 MW capacity) near Pensacola, Florida. The project is funded by the U.S. Department of Energy (DOE), Southern Company Services, Inc. (SCS on behalf of the entire Southern electric system), the Electric Power Research Institute (EPRI), and Ontario Hydro. SCS is the participant responsible for managing al aspects of this project. 1 ref., 69 figs., 45 tabs.

Does NGAL reduce costs? A cost analysis of urine NGAL (uNGAL) & serum creatinine (sCr) for acute kidney injury (AKI) diagnosis.

Science.gov (United States)

Parikh, Amay; Rizzo, John A; Canetta, Pietro; Forster, Catherine; Sise, Meghan; Maarouf, Omar; Singer, Eugenia; Elger, Antje; Elitok, Saban; Schmidt-Ott, Kai; Barasch, Jonathon; Nickolas, Thomas L

2017-01-01

Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a sensitive and specific diagnostic test for acute kidney injury (AKI) in the Emergency Department (ED), but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr) would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone. A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs. uNGAL plus sCr (uNGAL+sCr). A cost minimization analysis was performed to determine total expected costs for patients with AKI. uNGAL test characteristics were validated with eight-hundred forty-nine patients with sCr ≥1.5 from a completed study of 1635 patients recruited from EDs at two U.S. hospitals from 2007-8. Biomarker test, AKI work-up, and diagnostic imaging costs were incorporated. For a hypothetical cohort of 10,000 patients, the model predicted that the expected costs were $900 per patient (pp) in the sCr arm and $950 in the uNGAL+sCr arm. uNGAL+sCr resulted in 1,578 fewer patients with delayed diagnosis and treatment than sCr alone (2,013 vs. 436 pts) at center 1 and 1,973 fewer patients with delayed diagnosis and treatment than sCr alone at center 2 (2,227 vs. 254 patients). Although initial evaluation costs at each center were $50 pp higher in with uNGAL+sCr, total costs declined by $408 pp at Center 1 and by $522 pp at Center 2 due to expected reduced delays in diagnosis and treatment. Sensitivity analyses confirmed savings with uNGAL + sCr for a range of cost inputs. Using uNGAL with sCr as a clinical diagnostic test for AKI may improve patient management and reduce expected costs. Any cost savings would likely result from avoiding delays in diagnosis and treatment and from avoidance of unnecessary testing in patients given a false positive AKI diagnosis by use of sCr alone.

Does NGAL reduce costs? A cost analysis of urine NGAL (uNGAL & serum creatinine (sCr for acute kidney injury (AKI diagnosis.

Directory of Open Access Journals (Sweden)

Amay Parikh

Full Text Available Urine neutrophil gelatinase-associated lipocalin (uNGAL is a sensitive and specific diagnostic test for acute kidney injury (AKI in the Emergency Department (ED, but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone.A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs. uNGAL plus sCr (uNGAL+sCr. A cost minimization analysis was performed to determine total expected costs for patients with AKI. uNGAL test characteristics were validated with eight-hundred forty-nine patients with sCr ≥1.5 from a completed study of 1635 patients recruited from EDs at two U.S. hospitals from 2007-8. Biomarker test, AKI work-up, and diagnostic imaging costs were incorporated.For a hypothetical cohort of 10,000 patients, the model predicted that the expected costs were $900 per patient (pp in the sCr arm and $950 in the uNGAL+sCr arm. uNGAL+sCr resulted in 1,578 fewer patients with delayed diagnosis and treatment than sCr alone (2,013 vs. 436 pts at center 1 and 1,973 fewer patients with delayed diagnosis and treatment than sCr alone at center 2 (2,227 vs. 254 patients. Although initial evaluation costs at each center were $50 pp higher in with uNGAL+sCr, total costs declined by $408 pp at Center 1 and by $522 pp at Center 2 due to expected reduced delays in diagnosis and treatment. Sensitivity analyses confirmed savings with uNGAL + sCr for a range of cost inputs.Using uNGAL with sCr as a clinical diagnostic test for AKI may improve patient management and reduce expected costs. Any cost savings would likely result from avoiding delays in diagnosis and treatment and from avoidance of unnecessary testing in patients given a false positive AKI diagnosis by use of sCr alone.

Optical and Electronic NOx Sensors for Applications in Mechatronics

Directory of Open Access Journals (Sweden)

Scott D. Wolter

2009-05-01

Full Text Available Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i Quantum cascade lasers (QCL based photoacoustic (PA systems; ii gold nanoparticles as catalytically active materials in field-effect transistor (FET sensors, and iii functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling.

Optical and Electronic NOx Sensors for Applications in Mechatronics

Science.gov (United States)

Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A.; Wolter, Scott D.; Brown, April; Ricco, Mario

2009-01-01

Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling. PMID:22412315

Characteristics of Sucrose Transport through the Sucrose-Specific Porin ScrY Studied by Molecular Dynamics Simulations

Directory of Open Access Journals (Sweden)

Liping eSun

2016-02-01

Full Text Available Sucrose-specific porin (ScrY is a transmembrane protein that allows for the uptake of sucrose under growth-limiting conditions. The crystal structure of ScrY was resolved before by X-ray crystallography, both in its uncomplexed form and with bound sucrose. However, little is known about the molecular characteristics of the transport mechanism of ScrY. To date, there has not yet been any clear demonstration for sucrose transport through the ScrY.Here, the dynamics of the ScrY trimer embedded in a phospholipid bilayer as well as the characteristics of sucrose translocation were investigated by means of atomistic molecular dynamics (MD simulations. The potential of mean force (PMF for sucrose translocation through the pore showed two main energy barriers within the constriction region of ScrY. Energy decomposition allowed to pinpoint three aspartic acids as key residues opposing the passage of sucrose, all located within the L3 loop. Mutation of two aspartic acids to uncharged residues resulted in an accordingly modified electrostatics and decreased PMF barrier. The chosen methodology and results will aid in the design of porins with modified transport specificities.

Optimal Control as a method for Diesel engine efficiency assessment including pressure and NO_x constraints

International Nuclear Information System (INIS)

Guardiola, Carlos; Climent, Héctor; Pla, Benjamín; Reig, Alberto

2017-01-01

Highlights: • Optimal Control is applied for heat release shaping in internal combustion engines. • Optimal Control allows to assess the engine performance with a realistic reference. • The proposed method gives a target heat release law to define control strategies. - Abstract: The present paper studies the optimal heat release law in a Diesel engine to maximise the indicated efficiency subject to different constraints, namely: maximum cylinder pressure, maximum cylinder pressure derivative, and NO_x emission restrictions. With this objective, a simple but also representative model of the combustion process has been implemented. The model consists of a 0D energy balance model aimed to provide the pressure and temperature evolutions in the high pressure loop of the engine thermodynamic cycle from the gas conditions at the intake valve closing and the heat release law. The gas pressure and temperature evolutions allow to compute the engine efficiency and NO_x emissions. The comparison between model and experimental results shows that despite the model simplicity, it is able to reproduce the engine efficiency and NO_x emissions. After the model identification and validation, the optimal control problem is posed and solved by means of Dynamic Programming (DP). Also, if only pressure constraints are considered, the paper proposes a solution that reduces the computation cost of the DP strategy in two orders of magnitude for the case being analysed. The solution provides a target heat release law to define injection strategies but also a more realistic maximum efficiency boundary than the ideal thermodynamic cycles usually employed to estimate the maximum engine efficiency.

Sulfur poisoning and regeneration of the Ag/γ-Al2O3 catalyst for H2-assisted SCR of NOx by ammonia

DEFF Research Database (Denmark)

Doronkin, Dmitry E.; Khan, Tuhin Suvra; Bligaard, Thomas

2012-01-01

Sulfur poisoning and regeneration mechanisms for a 2% Ag/γ-Al2O3 catalyst for the H2-assisted selective catalytic reduction of NOx by NH3 are investigated. The catalyst has medium sulfur tolerance at low temperatures, however a good capability of regeneration at 670°C under lean conditions when H...

Modelling and Operation of Diesel Engine Exhaust Gas Cleaning Systems

DEFF Research Database (Denmark)

Åberg, Andreas

. Challenges with this technology include dosing the appropriate amount of urea to reach sufficient NOx conversion, while at the same time keeping NH3- slip from the exhaust system below the legislation. This requires efficient control algorithms. The focus of this thesis is modelling and control of the SCR...... parameters were estimated using bench-scale monolith isothermal data. Validation was done by simulating the out-put from a full-scale SCR monolith that was treating real engine gases from the European Transient Cycle (ETC). Results showed that the models were successfully calibrated, and that some......, and simulating the system....

Deactivation of SCR Catalysts by Additives

DEFF Research Database (Denmark)

Castellino, Francesco

2008-01-01

forskellige opløsninger af K3PO4. Resultaterne viste, at hvis K bindes i K-P saltforbindelser ville dette ikke reducere hastigheden af katalysatorens deaktivering. Regenereringstest udført i laboratoriet på katalysatorplader viste, at regenerering af de eksponerede katalysatorer var muligt ved at vaske demmed...... 0.5Mvandig opløsning af H2SO4. Somdet sidste blev en kommerciel V2O5-WO3-TiO2 SCR monolit eksponer et i 1000 timer for røggas tilsat en vandig opløsning af KCl, Ca(OH)2, H3PO4 og H2SO4 i en pilotopstilling. Blandingens sammensætning blev justeret med henblik på at have et P/K og P/Ca forhold på...... for KCl eller K3PO4. Dette faktum indikerer at kemisk binding af K i P-K-Ca-forbindelser er en effektiv måde at reducere den negative indflydelse på levetiden af vanadium baserede SCR katalysatorer hidrørende fra alkalimetaller. På den anden side blev fosforafsætning og -belægningsdannelse favoriseret ved...

Multiphase catalysts for selective reduction of NOx with hydrocarbons

NARCIS (Netherlands)

Maisuls, S.E.

2000-01-01

The combustion of fuels, to meet the society demands for energy, result in the emissi of large quantities of nitrogen oxides (NOx) to the environment. These pollutants cause severe environmental problems and present a serious hazard to the health. Nowadays, two methods for the control of NOx

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Temi Linjewile; Connie Senior; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding; Robert Hurt

2003-12-31

This is the fourteenth Quarterly Technical Report for DOE Cooperative Agreement No: DEFC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NOx control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. Using the initial CFD baseline modeling of the Gavin Station and the plant corrosion maps, six boiler locations for the corrosion probes were identified and access ports have been installed. Preliminary corrosion data obtained appear consistent and believable. In situ, spectroscopic experiments at BYU reported in part last quarter were completed. New reactor tubes have been made for BYU's CCR that allow for testing smaller amounts of catalyst and thus increasing space velocity; monolith catalysts have been cut and a small reactor that can accommodate these pieces for testing is in its final stages of construction. A poisoning study on Ca-poisoned catalysts was begun this quarter. A possible site for a biomass co-firing test of the slipstream reactor was visited this quarter. The slipstream reactor at Rockport required repair and refurbishment, and will be re-started in the next quarter. This report describes the final results of an experimental project at Brown University on the fundamentals of ammonia / fly ash interactions with relevance to the operation of advanced NOx control technologies such as selective catalytic reduction. The Brown task focused on the measurement of ammonia adsorption isotherms on commercial fly ash samples subjected to a variety of treatments and on the chemistry of dry and semi-dry ammonia removal processes.

An artificial intelligence (AI) NOx/heat rate optimization system for Ontario Hydro`s fossil generating stations

Energy Technology Data Exchange (ETDEWEB)

Luk, J.; Frank, A.; Bodach, P. [Ontario Hydro, Toronto, ON (Canada); Warriner, G. [Radian International, Tucker, GA (United States); Noblett, J. [Radian International, Austin, TX (United States); Slatsky, M. [Southern Company, Birmingham, AL (United States)

1999-08-01

Artificial intelligence (AI)-based software packages which can optimize power plant operations that improves heat rate and also reduces nitrogen oxide emissions are now commonly available for commercial use. This paper discusses the implementation of the AI-based NOx and Heat Rate Optimization System at Ontario Hydro`s generation stations, emphasizing the current AI Optimization Project at Units 5 and 6 of the Lakeview Generating Station. These demonstration programs are showing promising results in NOx reduction and plant performance improvement. The availability of the plant Digital Control System (DCS) in implementing AI optimization in a closed-loop system was shown to be an important criterion for success. Implementation of AI technology at other Ontario Hydro fossil generating units as part of the overall NOx emission reduction system is envisaged to coincide with the retrofit of the original plant control system with the latest DCS systems. 14 refs., 3 figs.

Understanding of self-terminating pulse generation using silicon controlled rectifier and RC load

Energy Technology Data Exchange (ETDEWEB)

Chang, Chris, E-mail: chrischang81@gmail.com; Karunasiri, Gamani, E-mail: karunasiri@nps.edu [Department of Physics, Naval Postgraduate School, Monterey, CA 93943 (United States); Alves, Fabio, E-mail: falves@alionscience.com [Alion Science and Technology at NPS, Monterey, CA 93943 (United States)

2016-01-15

Recently a silicon controlled rectifier (SCR)-based circuit that generates self-terminating voltage pulses was employed for the detection of light and ionizing radiation in pulse mode. The circuit consisted of a SCR connected in series with a RC load and DC bias. In this paper, we report the investigation of the physics underlying the pulsing mechanism of the SCR-based. It was found that during the switching of SCR, the voltage across the capacitor increased beyond that of the DC bias, thus generating a reverse current in the circuit, which helped to turn the SCR off. The pulsing was found to be sustainable only for a specific range of RC values depending on the SCR’s intrinsic turn-on/off times. The findings of this work will help to design optimum SCR based circuits for pulse mode detection of light and ionizing radiation without external amplification circuitry.

Preparation and Performance of Modified Red Mud-Based Catalysts for Selective Catalytic Reduction of NOx with NH3

Directory of Open Access Journals (Sweden)

Jingkun Wu

2018-01-01

Full Text Available Bayer red mud was selected, and the NH3-SCR activity was tested in a fixed bed in which the typical flue gas atmosphere was simulated. Combined with XRF, XRD, BET, SEM, TG and NH3-Temperature Programmed Desorption (TPD characterization, the denitration characteristics of Ce-doped red mud catalysts were studied on the basis of alkali-removed red mud. The results showed that typical red mud was a feasible material for denitration catalyst. Acid washing and calcining comprised the best treatment process for raw red mud, which reduced the content of alkaline substances, cleared the catalyst pore and optimized the particle morphology with dispersion. In the temperature range of 300–400 °C, the denitrification efficiency of calcined acid washing of red mud catalyst (ARM was more than 70%. The doping of Ce significantly enhanced NH3 adsorption from weak, medium and strong acid sites, reduced the crystallinity of α-Fe2O3 in ARM, optimized the specific surface area and broadened the active temperature window, which increased the NOx conversion rate by an average of nearly 20% points from 250–350 °C. The denitration efficiency of Ce0.3/ARM at 300 °C was as high as 88%. The optimum conditions for the denitration reaction of the Ce0.3/ARM catalyst were controlled as follows: Gas Hourly Space Velocity (GHSV of 30,000 h−1, O2 volume fraction of 3.5–4% and the NH3/NO molar ratio ([NH3/NO] of 1.0. The presence of SO2 in the feed had an irreversible negative effect on the activity of the Ce0.3/ARM catalyst.

Experimental Validation of a Virtual Engine-Out NOx Sensor for Diesel Emission Control

NARCIS (Netherlands)

Escobar Valdivieso, D.; Mentink, P.; Külah, S.; Forrai, A.; Willems, F.P.T.

2017-01-01

Motivated by automotive emissions legislations, a Virtual NOx sensor is developed. This virtual sensor consists of a real-time, phenomenological model that computes engine-out NOx by using the measured in-cylinder pressure signal from a single cylinder as its main input. The implementation is made

Characterization of Co and Fe-MCM-56 catalysts for NH3-SCR and N2O decomposition: An in situ FTIR study

Science.gov (United States)

Grzybek, Justyna; Gil, Barbara; Roth, Wieslaw J.; Skoczek, Monika; Kowalczyk, Andrzej; Chmielarz, Lucjan

2018-05-01

Two-step preparation of iron and cobalt-containing MCM-56 zeolites has been undertaken to evaluate the influence of their physicochemical properties in the selective catalytic reduction (NH3-SCR or DeNOx) of NO using NH3 as a reductant. Zeolites were prepared by the selective leaching of the framework cations by concentrated HNO3 solution and NH4F/HF mixture and consecutively, introduction of Co and Fe heteroatoms, in quantities below 1 wt%. Further calcination allowed to obtain highly dispersed active species. Their evaluation and speciation was realized by adsorption of pyridine and NO, followed by FTIR spectroscopy. Both Fe-MCM-56 zeolites showed excellent activities (maximum NO conversion 92%) with high selectivity to dinitrogen (above 99%) in the high temperature NH3-SCR process. High catalytic activity of Fe-MCM-56 zeolites was assigned to the formation of stable nitrates, delivering NO to react with NH3 at higher temperatures and suppressing the direct NO oxidation. It was found that more nitrates was formed in Fe-MCM-56 (HNO3) than in Fe-MCM-56 (HF/NH4F) and that could compensate for the lower Fe loading, resulting in very similar catalytic activity of both catalysts. At the same time both Co-and Fe-MCM-56 zeolites were moderately active in direct N2O decomposition, with maximum N2O conversion not higher than 80% and activity window starting at 500 °C. This phenomenon was expected since both types of catalysts contained well dispersed active centers, not beneficial for this reaction.

Optical and Electronic NO(x) Sensors for Applications in Mechatronics.

Science.gov (United States)

Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A; Wolter, Scott D; Brown, April; Ricco, Mario

2009-01-01

Current production and emerging NO(x) sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NO(x) show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NO(x) in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NO(x) sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling.

Laser diagnosis and plasma technology: Fundamentals for reduction of emissions and fuel consumption in DI internal combustion engines. Sub-project: Purification of diesel exhaust in pulsed plasma. Final report; Laserdiagnostische und plasmatechnologische Grundlagen zur Verminderung von Emissionen und Kraftstoffverbrauch von DI-Verbrennungsmotoren. Teilvorhaben: Reinigung von Dieselabgasen in gepulsten Plasmen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Hammer, T.; Kishimoto, T.; Birckigt, R.

2000-12-01

Selective catalytic reduction using ammonia based reducing agents is known to reduce the NOx-emissions from Diesel cars. However, it does not work efficiently under cold starting and urban driving conditions, because efficient reduction requires catalyst temperatures above 170 C. Without additional measures, pulsed plasma treatment does not cause reduction but mainly oxidation of nitric oxides preferably emitted as NO. By the combination of pulsed DBD-plasma treatment with selective catalytic reduction efficient NOx-reduction was obtained at catalyst temperatures below 170 C. It could be shown, that this low temperature reduction is a synergistic effect caused by plasma induced oxidation of some fraction of the NO. Based on this knowledge of the reaction mechanism plasma- and SCR-reactors were built, which were tested on a test bench equipped with a modern cars Diesel engine. Under cold starting and urban driving conditions by application of average plasma powers below 300 W the NOx-emissions were reduced for about 60%, the maximum degree of NOx-reduction was 85%. The plasma induced removal of hydrocarbons and particles, as well as the formation of by-products and the influence of hydrocarbons on the plasma induced selective catalytic reduction processes were investigated. No disadvantageous by-products could be found. (orig.) [German] Die selektive katalytische Reduktion mit Ammoniak als Reduktionsmittel ist ein bekanntes Verfahren zur Reduktion der Stickoxidemissionen von Diesel-Pkw, arbeitet aber erst ab Katalysatortemperaturen oberhalb 170 C und ist damit unter Kaltstart- und Stadtverkehrsbedingungen wenig wirksam. Gepulste Plasmen bewirken ohne zusaetzliche Massnahmen keine ausreichende chemische Reduktion sondern ueberwiegend Oxidation der als NO emittierten Stickoxide. Durch Kombination von DBE-Plasmen mit der selektiven katalytischen Reduktion hingegen konnte auch bei Katalysatortemperaturen unter 170 C wirkungsvolle NOx-Reduktion erzielt werden. Es konnte

A comparative study on methods of improving SCR for ship detection in SAR image

Science.gov (United States)

Lang, Haitao; Shi, Hongji; Tao, Yunhong; Ma, Li

2017-10-01

Knowledge about ship positions plays a critical role in a wide range of maritime applications. To improve the performance of ship detector in SAR image, an effective strategy is improving the signal-to-clutter ratio (SCR) before conducting detection. In this paper, we present a comparative study on methods of improving SCR, including power-law scaling (PLS), max-mean and max-median filter (MMF1 and MMF2), method of wavelet transform (TWT), traditional SPAN detector, reflection symmetric metric (RSM), scattering mechanism metric (SMM). The ability of SCR improvement to SAR image and ship detection performance associated with cell- averaging CFAR (CA-CFAR) of different methods are evaluated on two real SAR data.

Gaseous ligand selectivity of the H-NOX sensor protein from Shewanella oneidensis and comparison to those of other bacterial H-NOXs and soluble guanylyl cyclase.

Science.gov (United States)

Wu, Gang; Liu, Wen; Berka, Vladimir; Tsai, Ah-Lim

2017-09-01

To delineate the commonalities and differences in gaseous ligand discrimination among the heme-based sensors with Heme Nitric oxide/OXygen binding protein (H-NOX) scaffold, the binding kinetic parameters for gaseous ligands NO, CO, and O 2 , including K D , k on , and k off , of Shewanella oneidensis H-NOX (So H-NOX) were characterized in detail in this study and compared to those of previously characterized H-NOXs from Clostridium botulinum (Cb H-NOX), Nostoc sp. (Ns H-NOX), Thermoanaerobacter tengcongensis (Tt H-NOX), Vibrio cholera (Vc H-NOX), and human soluble guanylyl cyclase (sGC), an H-NOX analogue. The K D (NO) and K D (CO) of each bacterial H-NOX or sGC follow the "sliding scale rule"; the affinities of the bacterial H-NOXs for NO and CO vary in a small range but stronger than those of sGC by at least two orders of magnitude. On the other hand, each bacterial H-NOX exhibits different characters in the stability of its 6c NO complex, reactivity with secondary NO, stability of oxyferrous heme and autoxidation to ferric heme. A facile access channel for gaseous ligands is also identified, implying that ligand access has only minimal effect on gaseous ligand selectivity of H-NOXs or sGC. This comparative study of the binding parameters of the bacterial H-NOXs and sGC provides a basis to guide future new structural and functional studies of each specific heme sensor with the H-NOX protein fold. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Ships going slow in reducing their NOx emissions

NARCIS (Netherlands)

Boersma, K.F.; Vinken, G.C.M.; Tournadre, J.

2015-01-01

Weaddress the lack of temporal information on ship emissions, and report on rapid short-term variations of satellite-derived shipNOx emissions between 2005 and 2012 over European seas. Our inversion is based onOMI observed troposphericNO2 columns and GEOS-Chem simulations. Average European shipNOx

Selective catalytic reduction system and process using a pre-sulfated zirconia binder

Science.gov (United States)

Sobolevskiy, Anatoly; Rossin, Joseph A.

2010-06-29

A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO.sub.2)SO.sub.4, palladium, and a pre-sulfated zirconia binder. The inclusion of a pre-sulfated zirconia binder substantially increases the durability of a Pd-based SCR catalyst system. A system for implementing the disclosed process is further provided.

NOx Reduction Technology in Diesel Engine Exhaust by the Plasmatron

International Nuclear Information System (INIS)

Joa, Sang Beom

2008-02-01

completeness of the partial fuel oxidation reaction up to 100%. Nitrogen was found to be the most effective gas for the synthesis gas production by a plasmatron. The preliminary experiments of introducing the reformation products into a diesel engine resulted in ∼25% NOx cut in the exhaust gas flow. A simulation experiment with the pure hydrogen addition to the inlet of a diesel engine showed that both components of the synthesis gas H 2 and CO fed into the engine play significant role in cutting NOx content in the engine's emission. The selective catalytic reduction (SCR) with propylene and decane as reductants in the presence of excess air over (Fe, Co-Pt)/ZSM-5 catalyst was conducted to remove NOx from Diesel exhaust gases. The SO 2 effect and deactivation test over above catalyst were also executed. ZSM-5 supported Co, Pt, Fe mixed oxide catalyst showed about 80% of conversion in the presence of NO. However, the activity was decreased when the catalyst was wash coated onto the ceramic monolith. We found that the deNOx activity over the catalyst was strongly depended on the amount of reductant. Therefore, the amount reductant and how to feed the reductant into the system should be considered as important factors to remove NOx. In order to develop the high removal NOx activity at low temperature and maintain the stable activity at the real exhaust gases condition, metallosilicate and Pt/ZSM-5 catalysts have been used. In case of metallosilicate catalyst, the deNOx activity was low at the oxidation atmospheric condition. When the Pt was ion-exchanged with ZSM-5, the H-form of ZSM-5 catalyst showed high deNOx activity. The effect of reductant type on deNOx activity exhibited that the olefin system provided more higher activity than octane system. The methane conversion observed in the presence of NO and excess O 2 over alumina supported Pt catalyst. In order to improve the activity and durability, the Co metal ion was added. The result showed that the Co-Pt catalyst gave

Optimisation of Ag loading and alumina characteristics to give sulphur-tolerant Ag/Al₂O₃ catalyst for H₂-assisted NH₃-SCR of NO_x

DEFF Research Database (Denmark)

Fogel, Sebastian; Doronkin, Dmitry E.; Gabrielsson, Pär

2012-01-01

A series of Ag/Al2O3 catalysts with different alumina precursors and different Ag loadings were tested for H2 assisted NH3-SCR of NO. The catalysts were characterised (BET, XRD, NH3-TPD, ICP-OES, TEM and UV–vis spectroscopy) and tested as fresh catalyst, during long-term cycling tests with SO2 pr....... A higher Ag loading will affect the state of Ag by increasing the ratio of Ag-clusters and particles to highly dispersed Ag ions. SO2-poisoned Ag-clusters and particles can be regenerated by the high temperature treatment in the deNOx feed, highly dispersed Ag ions cannot....

Atmospheric emission of NOx from mining explosives: A critical review

Science.gov (United States)

Oluwoye, Ibukun; Dlugogorski, Bogdan Z.; Gore, Jeff; Oskierski, Hans C.; Altarawneh, Mohammednoor

2017-10-01

High-energy materials such as emulsions, slurries and ammonium-nitrate fuel-oil (ANFO) explosives play crucial roles in mining, quarrying, tunnelling and many other infrastructure activities, because of their excellent transport and blasting properties. These explosives engender environmental concerns, due to atmospheric pollution caused by emission of dust and nitrogen oxides (NOx) from blasts, the latter characterised by the average emission factor of 5 kg (t AN explosive)-1. This first-of-its-kind review provides a concise literature account of the formation of NOx during blasting of AN-based explosives, employed in surface operations. We estimate the total NOx emission rate from AN-based explosives as 0.05 Tg (i.e., 5 × 104 t) N per annum, compared to the total global annual anthropogenic NOx emissions of 41.3 × 106 t N y-1. Although minor in the global sense, the large localised plumes from blasting exhibit high NOx concentration (500 ppm) exceeding up to 3000 times the international standards. This emission has profound consequences at mining sites and for adjacent atmospheric environment, necessitating expensive management of exclusion zones. The review describes different types of AN energetic materials for civilian applications, and summarises the essential properties and terminologies pertaining to their use. Furthermore, we recapitulate the mechanisms that lead to the formation of the reactive nitrogen species in blasting of AN-based explosives, review their implications to atmospheric air pollution, and compare the mechanisms with those experienced in other thermal and combustion operations. We also examine the mitigation approaches, including guidelines and operational-control measures. The review discusses the abatement technologies such as the formulation of new explosive mixtures, comprising secondary fuels, spin traps and other additives, in light of their effectiveness and efficiency. We conclude the review with a summary of unresolved problems

Variability in operation-based NO(x) emission factors with different test routes, and its effects on the real-driving emissions of light diesel vehicles.

Science.gov (United States)

Lee, Taewoo; Park, Junhong; Kwon, Sangil; Lee, Jongtae; Kim, Jeongsoo

2013-09-01

The objective of this study is to quantify the differences in NO(x) emissions between standard and non-standard driving and vehicle operating conditions, and to estimate by how much NO(x) emissions exceed the legislative emission limits under typical Korean road traffic conditions. Twelve Euro 3-5 light-duty diesel vehicles (LDDVs) manufactured in Korea were driven on a chassis dynamometer over the standard New European Driving Cycle (NEDC) and a representative Korean on-road driving cycle (KDC). NO(x) emissions, average speeds and accelerations were calculated for each 1-km trip segment, so called averaging windows. The results suggest that the NO(x) emissions of the tested vehicles are more susceptible to variations in the driving cycles than to those in the operating conditions. Even under comparable operating conditions, the NO(x) control capabilities of vehicles differ from each other, i.e., NO(x) control is weaker for the KDC than for the NEDC. The NO(x) emissions over the KDC for given vehicle operating conditions exceed those over the NEDC by more than a factor of 8. Consequently, on-road NO(x) emission factors are estimated here to exceed the Euro 5 emission limit by up to a factor of 8, 4 and 3 for typical Korean urban, rural, and motorway road traffic conditions, respectively. Our findings support the development of technical regulations for supplementary real-world emission tests for emission certification and the corresponding research actions taken by automotive industries. Copyright © 2013 Elsevier B.V. All rights reserved.

Hollow fiber contractors for simultaneous SOx/NOx removal

International Nuclear Information System (INIS)

Bhown, A.S.; Pakala, N.R.; Riggs, T.

1995-01-01

Control of SO x and NO x emissions from coal-fired utility and industrial boilers is a topic of growing national and international importance. Whereas a host of commercial and semicommercial processes exist, increasingly stringent emission standards mandate that processes be low cost, highly efficient, and, ideally, produce marketable byproducts. Although a wide range of site-specific economic factors dictate the best choice of SO x and NO x control, removal of SO 2 by wet limestone scrubbing and removal of NO x by selective catalytic reduction (SCR) are regarded as the best commercialized technologies for this application. A typical wet limestone plant requires approximately $100 to $120 of capital investment per kilowatt of electric power generating capacity and has power and miscellaneous operating costs in the range of 5 to 6 mils per kilowatt hour (kWh). The SCR process requires approximately $70 to $100 of capital investment per kilowatt of electric power generating capacity. Its operating costs, including ammonia consumption, is in the range of 1.8 to 2.2 mils per kWh. These costs can add approximately 20% to the final cost of generated electricity, a significant burden on rate payers

Atmospheric pollution reduction effect and regional predicament: An empirical analysis based on the Chinese provincial NOx emissions.

Science.gov (United States)

Ding, Lei; Liu, Chao; Chen, Kunlun; Huang, Yalin; Diao, Beidi

2017-07-01

Atmospheric pollution emissions have become a matter of public concern in recent years. However, most of the existing researches on NOx pollution are from the natural science and technology perspective, few studies have been conducted from an economic point, and regional differences have not been given adequate attention. This paper adopts provincial panel data from 2006 to 2013 and the LMDI model to analyze the key driving factors and regional dilemmas of NOx emissions. The results show that significant regional disparities still exit on NO x emissions and its reduction effect 27 provinces didn't accomplish their corresponding reduction targets. Economic development factor is the dominating driving factor of NO x emissions during the study period, while energy efficiency and technology improvement factors offset total NO x emissions in the majority of provinces. In addition, the industrial structure factor plays a more significant role in reducing the NO x emissions after 2011. Therefore, the government should consider all these factors as well as regional heterogeneity in developing appropriate pollution mitigating policies. It's necessary to change NOx emissions control attitude from original key areas control to divided-zone control, not only attaches great importance to the reduction of the original key areas, but also emphasizes the new potential hotspots with high NO x emissions. Copyright © 2017 Elsevier Ltd. All rights reserved.

A space-based, high-resolution view of notable changes in urban NOx pollution around the world (2005-2014)

Science.gov (United States)

Duncan, Bryan N.; Lamsal, Lok N.; Thompson, Anne M.; Yoshida, Yasuko; Lu, Zifeng; Streets, David G.; Hurwitz, Margaret M.; Pickering, Kenneth E.

2016-01-01

Nitrogen oxides (NOx = NO + NO2) are produced during combustion processes and, thus may serve as a proxy for fossil fuel-based energy usage and coemitted greenhouse gases and other pollutants. We use high-resolution nitrogen dioxide (NO2) data from the Ozone Monitoring Instrument (OMI) to analyze changes in urban NO2 levels around the world from 2005 to 2014, finding complex heterogeneity in the changes. We discuss several potential factors that seem to determine these NOx changes. First, environmental regulations resulted in large decreases. The only large increases in the United States may be associated with three areas of intensive energy activity. Second, elevated NO2 levels were observed over many Asian, tropical, and subtropical cities that experienced rapid economic growth. Two of the largest increases occurred over recently expanded petrochemical complexes in Jamnagar (India) and Daesan (Korea). Third, pollution transport from China possibly influenced the Republic of Korea and Japan, diminishing the impact of local pollution controls. However, in China, there were large decreases over Beijing, Shanghai, and the Pearl River Delta, which were likely associated with local emission control efforts. Fourth, civil unrest and its effect on energy usage may have resulted in lower NO2 levels in Libya, Iraq, and Syria. Fifth, spatial heterogeneity within several megacities may reflect mixed efforts to cope with air quality degradation. We also show the potential of high-resolution data for identifying NOx emission sources in regions with a complex mix of sources. Intensive monitoring of the world's tropical/subtropical megacities will remain a priority, as their populations and emissions of pollutants and greenhouse gases are expected to increase significantly.

A Space-based, High-resolution View of Notable Changes in Urban Nox Pollution Around the World (2005 - 2014)

Science.gov (United States)

Duncan, Bryan N.; Lamsal, Lok N.; Thompson, Anne M.; Yoshida, Yasuko; Lu, Zifeng; Streets, David G.; Hurwitz, Margaret M.; Pickering, Kenneth E.

2016-01-01

Nitrogen oxides (NOxNO+NO2) are produced during combustion processes and, thus may serve as a proxy for fossil fuel-based energy usage and committed greenhouse gases and other pollutants. We use high-resolution nitrogen dioxide (NO2) data from the Ozone Monitoring Instrument (OMI) to analyze changes in urban NO2 levels around the world from 2005 to 2014, finding complex heterogeneity in the changes. We discuss several potential factors that seem to determine these NOx changes. First, environmental regulations resulted in large decreases. The only large increases in the United States may be associated with three areas of intensive energy activity. Second, elevated NO2 levels were observed over many Asian, tropical, and subtropical cities that experienced rapid economic growth. Two of the largest increases occurred over recently expanded petrochemical complexes in Jamnagar (India) and Daesan (Korea). Third, pollution transport from China possibly influenced the Republic of Korea and Japan, diminishing the impact of local pollution controls. However, in China, there were large decreases over Beijing, Shanghai, and the Pearl River Delta, which were likely associated with local emission control efforts. Fourth, civil unrest and its effect on energy usage may have resulted in lower NO2 levels in Libya, Iraq, and Syria. Fifth, spatial heterogeneity within several megacities may reflect mixed efforts to cope with air quality degradation. We also show the potential of high-resolution data for identifying NOx emission sources in regions with a complex mix of sources. Intensive monitoring of the world's tropical subtropical megacities will remain a priority, as their populations and emissions of pollutants and greenhouse gases are expected to increase significantly.

Experiments and simulations of NOx formation in the combustion of hydroxylated fuels

KAUST Repository

Bohon, Myles

2015-06-01

This work investigates the influence of molecular structure in hydroxylated fuels (i.e. fuels with one or more hydroxyl groups), such as alcohols and polyols, on NOx formation. The fuels studied are three lower alcohols (methanol, ethanol, and n-propanol), two diols (1,2-ethanediol and 1,2-propanediol), and one triol (1,2,3-propanetriol); all of which are liquids at room temperature and span a wide range of thermophysical properties. Experimental stack emissions measurements of NO/NO2, CO, and CO2 and flame temperature profiles utilizing a rake of thermocouples were obtained in globally lean, swirling, liquid atomized spray flames inside a refractory-lined combustion chamber as a function of the atomizing air flow rate and swirl number. These experiments show significantly lower NOx formation with increasing fuel oxygen content despite similarities in the flame temperature profiles. By controlling the temperature profiles, the contribution to NOx formation through the thermal mechanism were matched, and variations in the contribution through non-thermal NOx formation pathways are observed. Simulations in a perfectly stirred reactor, at conditions representative of those measured within the combustion region, were conducted as a function of temperature and equivalence ratio. The simulations employed a detailed high temperature chemical kinetic model for NOx formation from hydroxylated fuels developed based on recent alcohol combustion models and extended to include polyol combustion chemistry. These simulations provide a qualitative comparison to the range of temperatures and equivalence ratios observed in complex swirling flows and provide insight into the influence of variations in the fuel decomposition pathways on NOx formation. It is observed that increasing the fuel bound oxygen concentration ultimately reduces the formation of NOx by increasing the proportion of fuel oxidized through formaldehyde, as opposed to acetylene or acetaldehyde. The subsequent

ROS-induced ROS release orchestrated by Nox4, Nox2, and mitochondria in VEGF signaling and angiogenesis.

Science.gov (United States)

Kim, Young-Mee; Kim, Seok-Jo; Tatsunami, Ryosuke; Yamamura, Hisao; Fukai, Tohru; Ushio-Fukai, Masuko

2017-06-01

Reactive oxygen species (ROS) derived from NADPH oxidase (NOX) and mitochondria play a critical role in growth factor-induced switch from a quiescent to an angiogenic phenotype in endothelial cells (ECs). However, how highly diffusible ROS produced from different sources can coordinate to stimulate VEGF signaling and drive the angiogenic process remains unknown. Using the cytosol- and mitochondria-targeted redox-sensitive RoGFP biosensors with real-time imaging, here we show that VEGF stimulation in human ECs rapidly increases cytosolic RoGFP oxidation within 1 min, followed by mitochondrial RoGFP oxidation within 5 min, which continues at least for 60 min. Silencing of Nox4 or Nox2 or overexpression of mitochondria-targeted catalase significantly inhibits VEGF-induced tyrosine phosphorylation of VEGF receptor type 2 (VEGFR2-pY), EC migration and proliferation at the similar extent. Exogenous hydrogen peroxide (H 2 O 2 ) or overexpression of Nox4, which produces H 2 O 2 , increases mitochondrial ROS (mtROS), which is prevented by Nox2 siRNA, suggesting that Nox2 senses Nox4-derived H 2 O 2 to promote mtROS production. Mechanistically, H 2 O 2 increases S36 phosphorylation of p66Shc, a key mtROS regulator, which is inhibited by siNox2, but not by siNox4. Moreover, Nox2 or Nox4 knockdown or overexpression of S36 phosphorylation-defective mutant p66Shc(S36A) inhibits VEGF-induced mtROS, VEGFR2-pY, EC migration, and proliferation. In summary, Nox4-derived H 2 O 2 in part activates Nox2 to increase mtROS via pSer36-p66Shc, thereby enhancing VEGFR2 signaling and angiogenesis in ECs. This may represent a novel feed-forward mechanism of ROS-induced ROS release orchestrated by the Nox4/Nox2/pSer36-p66Shc/mtROS axis, which drives sustained activation of angiogenesis signaling program. Copyright © 2017 the American Physiological Society.

Regional Marginal Abatement Cost Curves for NOx

Data.gov (United States)

U.S. Environmental Protection Agency — Data underlying the figures included in the manuscript "Marginal abatement cost curve for NOx incorporating controls, renewable electricity, energy efficiency and...

Rise and fall of the NOx emissions trade; Opkomst en ondergang van NOx-emissiehandel

Energy Technology Data Exchange (ETDEWEB)

Van der Velde, R. [Royal Haskoning DHV, Amersfoort (Netherlands); Van der Kolk, J. [Van der Kolk Advies, Soest (Netherlands)

2013-04-15

In 2005, the Netherlands started NOx emission trading. In 2014 they are terminating these activities. Are they stopping because the targets have been realized? This article provides an overview of the developments and experiences that have ultimately led to the termination of the NOx emission trade in the Netherlands [Dutch] In 2005 is Nederland begonnen in NOx-emissiehandel. In 2014 stoppen we er weer mee. Stoppen we omdat de doelen zijn gehaald? Een overzicht wordt gegeven van de ontwikkelingen en ervaringen die uiteindelijk hebben geleid tot beeindiging van de NOx-emissiehandel in Nederland.

Second Generation Advanced Reburning for High Efficiency NOx Control

International Nuclear Information System (INIS)

Zamansky, Vladimir M.; Maly, Peter M.; Sheldon, Mark; Seeker, W. Randall; Folsom, Blair A.

1997-01-01

Energy and Environmental Research Corporation is developing a family of high efficiency and low cost NO x control technologies for coal fired utility boilers based on Advanced Reburning (AR), a synergistic integration of basic reburning with injection of an N-agent. In conventional AR, injection of the reburn fuel is followed by simultaneous N-agent and overfire air injection. The second generation AR systems incorporate several components which can be used in different combinations. These components include: (1) Reburning Injection of the reburn fuel and overfire air. (2) N-agent Injection The N-agent (ammonia or urea) can be injected at different locations: into the reburning zone, along with the overfire air, and downstream of the overfire air injection. (3) N-agent Promotion Several sodium compounds can considerably enhance the NO x control from N-agent injection. These ''promoters'' can be added to aqueous N-agents. (4) Two Stages of N-agent Injection and Promotion Two N-agents with or without promoters can be injected at different locations for deeper NO x control. AR systems are intended for post-RACT applications in ozone non-attainment areas where NO x control in excess of 80% is required. AR will provide flexible installations that allow NO x levels to be lowered when regulations become more stringent. The total cost of NO x control for AR systems is approximately half of that for SCR. Experimental and kinetic modeling results for development of these novel AR systems are presented. Tests have been conducted in a 1.0 MMBtu/hr Boiler Simulator Facility with coal as the main fuel and natural gas as the reburning fuel. The results show that high efficiency NO x control, in the range 84-95%, can be achieved with various elements of AR. A comparative byproduct emission study was performed to compare the emissions from different variants of AR with commercial technologies (reburning and SNCR). For each technology sampling included: CO, SO 2 , N 2 O, total

NOx emission control for gas turbines: A 1991 update on regulations and technology (Part II)

International Nuclear Information System (INIS)

Schorr, M.M.

1991-01-01

The technologies that are available for the control of NO x emissions from gas turbines utilize the factors that impact the formation of NO x described in the previous section and include (1) diluent injection (i.e., water or steam) into the combustion zone, which is a front-end control technology that lowers the combustor flame temperature, (2) selective catalytic reduction (SCR), which is a back-end exhaust gas cleanup system, (3) dry low NO x combustors (DLN), which use staged combustion and very lean fuel-air mixtures (they are currently being introduced), and (4) catalytic combustion systems that hold the promise of achieving extremely low emission levels without resorting to exhaust gas cleanup. This last option is being developed to burn very lean fuel-air mixtures, but will require significant technological breakthroughs; it is still several years away from becoming commercially available

Regeneration of Pt-catalysts deactivated in municipal waste flue gas with H2/N2 and the effect of regeneration step on the SCR catalyst

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Rasmussen, Søren Brik; Kustov, Arkady

The deactivation performance of Pt-catalysts for CO oxidation has been studied in relation to use in sewage sludge municipal waste burners, where HMDS was found to poison the industrial catalyst in a similar way to the model Pt/TiO2 catalyst. A promising regeneration procedure was developed based...... on reduction with hydrogen. This procedure had negligible effect on the performance of the SCR catalyst. After treatment with 2% H2, 8% O2 in N2 for one hour, a slight better NO SCR activity was observed due to increase in the concentration V4+ sites. However, after exposure in normal NO SCR gases the activity...

Energy industry

Science.gov (United States)

Staszak, Katarzyna; Wieszczycka, Karolina

2018-04-01

The potential sources of metals from energy industries are discussed. The discussion is organized based on two main metal-contains wastes from power plants: ashes, slags from combustion process and spent catalysts from selective catalytic NOx reduction process with ammonia, known as SCR. The compositions, methods of metals recovery, based mainly on leaching process, and their further application are presented. Solid coal combustion wastes are sources of various compounds such as silica, alumina, iron oxide, and calcium. In the case of the spent SCR catalysts mainly two metals are considered: vanadium and tungsten - basic components of industrial ones.

Nox2 and p47phox modulate compensatory growth of primary collateral arteries

Science.gov (United States)

DiStasi, Matthew R.; Unthank, Joseph L.

2014-01-01

The role of NADPH oxidase (Nox) in both the promotion and impairment of compensatory collateral growth remains controversial because the specific Nox and reactive oxygen species involved are unclear. The aim of this study was to identify the primary Nox and reactive oxygen species associated with early stage compensatory collateral growth in young, healthy animals. Ligation of the feed arteries that form primary collateral pathways in rat mesentery and mouse hindlimb was used to assess the role of Nox during collateral growth. Changes in mesenteric collateral artery Nox mRNA expression determined by real-time PCR at 1, 3, and 7 days relative to same-animal control arteries suggested a role for Nox subunits Nox2 and p47phox. Administration of apocynin or Nox2ds-tat suppressed collateral growth in both rat and mouse models, suggesting the Nox2/p47phox interaction was involved. Functional significance of p47phox expression was assessed by evaluation of collateral growth in rats administered p47phox small interfering RNA and in p47phox−/− mice. Diameter measurements of collateral mesenteric and gracilis arteries at 7 and 14 days, respectively, indicated no significant collateral growth compared with control rats or C57BL/6 mice. Chronic polyethylene glycol-conjugated catalase administration significantly suppressed collateral development in rats and mice, implying a requirement for H2O2. Taken together, these results suggest that Nox2, modulated at least in part by p47phox, mediates early stage compensatory collateral development via a process dependent upon peroxide generation. These results have important implications for the use of antioxidants and the development of therapies for peripheral arterial disease. PMID:24633549

Multi-annual changes of NOx emissions in megacity regions: nonlinear trend analysis of satellite measurement based estimates

Directory of Open Access Journals (Sweden)

J. P. Burrows

2010-09-01

Full Text Available Hazardous impact of air pollutant emissions from megacities on atmospheric composition on regional and global scales is currently an important issue in atmospheric research. However, the quantification of emissions and related effects is frequently a difficult task, especially in the case of developing countries, due to the lack of reliable data and information. This study examines possibilities to retrieve multi-annual NOx emissions changes in megacity regions from satellite measurements of nitrogen dioxide and to quantify them in terms of linear and nonlinear trends. By combining the retrievals of the GOME and SCIAMACHY satellite instrument data with simulations performed by the CHIMERE chemistry transport model, we obtain the time series of NOx emission estimates for the 12 largest urban agglomerations in Europe and the Middle East in the period from 1996 to 2008. We employ then a novel method allowing estimation of a nonlinear trend in a noisy time series of an observed variable. The method is based on the probabilistic approach and the use of artificial neural networks; it does not involve any quantitative a priori assumptions. As a result, statistically significant nonlinearities in the estimated NOx emission trends are detected in 5 megacities (Bagdad, Madrid, Milan, Moscow and Paris. Statistically significant upward linear trends are detected in Istanbul and Tehran, while downward linear trends are revealed in Berlin, London and the Ruhr agglomeration. The presence of nonlinearities in NOx emission changes in Milan, Paris and Madrid is confirmed by comparison of simulated NOx concentrations with independent air quality monitoring data. A good quantitative agreement between the linear trends in the simulated and measured near surface NOx concentrations is found in London.

Dosimeter-Type NOx Sensing Properties of KMnO4 and Its Electrical Conductivity during Temperature Programmed Desorption

Directory of Open Access Journals (Sweden)

Ralf Moos

2013-04-01

Full Text Available An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT for NOx storage catalysts (NSC enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD. The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1 time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2 during the short-term thermal NOx release.

Formation of fuel NOx during black-liquor combustion

International Nuclear Information System (INIS)

Nichols, K.M.; Lien, S.J.

1993-01-01

Fuel NOx and thermal NOx were measured in combustion gases from black liquors in two laboratory furnaces. Combustion at 950 C in air (8% O 2 ) produced NOx concentrations of 40-80ppm. Combustion at 950 C in synthetic air containing no nitrogen (21% 0 2 in Ar) produced the same result, demonstrating that all of the NOx produced during combustion at 950 C was fuel NOx. Formation of fuel NOx increased moderately with increasing temperature in the range of 800-1,000 C, but temperature sensitivity of fuel NOx was much less than that of thermal NOx. The results imply that the major source of NOx in recovery furnace emissions is the fuel NOx in recovery furnace formed by conversion of liquor-bound nitrogen during combustion. This is consistent with thermal NOx theory, which postulates that black-liquor combustion temperatures are too low to generate significant amounts of thermal NOx

New insights into Cu/SSZ-13 SCR catalyst acidity. Part I: Nature of acidic sites probed by NH 3 titration

Energy Technology Data Exchange (ETDEWEB)

Luo, Jinyong; Gao, Feng; Kamasamudram, Krishna; Currier, Neal; Peden, Charles H. F.; Yezerets, Aleksey

2017-04-01

In this work we investigated an unusual acidity feature of a Cu/SSZ-13 catalyst used in selective catalytic reduction of NOx with NH3 (NH3-SCR). In particular, this catalyst showed two distinct NH3 desorption peaks in NH3-TPD measurements, in contrast to single, unresolved desorption peaks observed for other Cu-exchanged zeolites conventionally used in the SCR studies, including its isostructural but chemically different analogue Cu/SAPO-34. We further observed that the intensities of the two TPD peaks, which represented the amount of stored NH3, changed in opposite directions in response to progressive mild hydrothermal aging, while the total storage capacity was preserved. We proposed an explanation for this remarkable behavior, by using model reference samples and additional characterization techniques. At least three NH3 storage sites were identified: two distinct populations of Cu sites responsible for low-temperature NH3 storage, and Brønsted acid sites responsible for high-temperature NH3 storage. Contrary to the commonly accepted mechanism that Brønsted acid site loss during hydrothermal aging is driven by dealumination, we concluded that the decline in the number of Brønsted acid sites upon mild hydrothermal aging for Cu/SSZ-13 was not due to dealumination, but rather transformation of Cu sites, i.e., gradual conversion of ZCuOH (Cu2+ singly coordinated with Zeolite) to Z2Cu (Cu2+ doubly coordinated with Zeolite). This transformation was responsible for the increased low-temperature desorption peak in NH3-TPD since each ZCuOH adsorbed ~1 NH3 molecule while each Z2Cu adsorbed ~2 NH3 molecules under the conditions used here. These findings were used in Part II of this series of studies to develop a method for quantifying hydrothermal ageing of industrial Cu/SSZ-13 SCR catalysts. Authors would like to thank Randall Jines for his help with collecting the reactor data, Nancy W. Washton for measuring the NMR data and Tamas Varga for in-situ XRD measurements

An engineering approach to the design and construction of a small modular stellarator for magnetic confinement of plasma. SCR-1

International Nuclear Information System (INIS)

Barillas, Laura; Vargas, V. Iván; Alpízar, Asdrúval

2011-01-01

This paper briefly describes the design and construction of Stellarator of Costa Rica 1 (SCR-1) from an engineering perspective. SCR-1 is a small modular Stellarator for magnetic confinement of plasma developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica (ITCR). The SCR-1 is based on the small Spanish Stellarator UST 1 (Ultra Small Torus 1), created by engineer Vicente Queral. Some of the characteristics of the SCR-1 are the following: it will be a 2-field period modular stellarator with an aspect ratio ≈ 6; low shear configuration with core and edge rotational transform equal to 0.32 and 0.28; it will employ stainless steel torus-shaped vacuum vessel which will hold a plasma with an average radius a ≈ 42.2 mm, a volume of 8 liters (0.008 m 3 ), and major radius R = 238 mm. This plasma will be confined by a magnetic field (B ≈ 90 mT) given by 12 modular coils with 12 turns each, carrying a current of 725 A per turn providing a total toroidal field (TF) current of 8.7 kA-turn per coil. The coils will be supplied by a bank of cell batteries of 120 V. Typical length of the plasma pulse will be between 4 s to 10 s. The plasma heating will be achieved by electron cyclotron radio-frequency (ECH) from two magnetrons providing a total power of 5 kW, at a frequency of 2.45 GHz corresponding to the first harmonic (B 0 = 87.8 mT). The expected electron temperature and density are 15 eV and 7x10 16 m -3 respectively. The initial diagnostics on the SCR-1 will consist of a Langmuir probe with a displacement system, a heterodyne microwave interferometer (frequency of 28 GHz, corresponding to a wavelength of λ = 10.71 mm). The first plasma of the SCR-1 is expected at the beginning of 2012. (author)

Rejuvenation of the SCR catalyst at Mehrum

Energy Technology Data Exchange (ETDEWEB)

Nagai, Y.; Inatsume, Y.; Morita, I.; Kato, Y.; Yokoyama, K.; Ito, K. [Babcock Hitachi K.K., Kure-shi, Hiroshima-ken (Japan)

2004-07-01

Babcock Hitachi K.K. (BHK) received the contract of the rejuvenation of the SCR catalyst at the 750 MW coal-fired Mehrum Power Station (in Hohenhameln, Germany) in March 2003. The contractual coverage was 160 m{sup 3} of the entire catalyst layer. The catalyst, which had been in operation for 16 years since 1987, was originally supplied by BHK. The rejuvenation process developed for the Mehrum project consisted of two major steps: the first is to dust off the catalyst and remove the catalyst poison, and the second step is to add active material to enhance the catalyst activity. The catalyst must be dried after each washing. In order to minimize transportation cost and time, the rejuvenation work was done at the Mehrum station site. The scope of the rejuvenation work was shared between the owner and BHK. It took about one and a half months to complete the (total) on-site rejuvenation worked. The performance of the rejuvenated catalyst was superior to show the same level of activity as the unused catalyst and maintain the same SO{sub 2} conversion rate as the spent catalyst. This paper gives the details of the spent coal-fired SCR catalyst rejuvenation work. 13 figs., 1 tab.

Gaseous emissions from a heavy-duty engine equipped with SCR aftertreatment system and fuelled with diesel and biodiesel: Assessment of pollutant dispersion and health risk

Energy Technology Data Exchange (ETDEWEB)

Tadano, Yara S.; Borillo, Guilherme C.; Godoi, Ana Flávia L.; Cichon, Amanda; Silva, Thiago O.B.; Valebona, Fábio B.; Errera, Marcelo R. [Environmental Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil); Penteado Neto, Renato A.; Rempel, Dennis; Martin, Lucas [Institute of Technology for Development, Lactec–Leme Division, 01 LothárioMeissner Ave., Curitiba, PR, 80210-170 (Brazil); Yamamoto, Carlos I. [Chemical Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil); Godoi, Ricardo H.M., E-mail: rhmgodoi@ufpr.br [Environmental Engineering Department, Federal University of Parana, 210 Francisco H. dos Santos St., Curitiba, PR, 81531-980 Brazil (Brazil)

2014-12-01

The changes in the composition of fuels in combination with selective catalytic reduction (SCR) emission control systems bring new insights into the emission of gaseous and particulate pollutants. The major goal of our study was to quantify NO{sub x}, NO, NO{sub 2}, NH{sub 3} and N{sub 2}O emissions from a four-cylinder diesel engine operated with diesel and a blend of 20% soybean biodiesel. Exhaust fume samples were collected from bench dynamometer tests using a heavy-duty diesel engine equipped with SCR. The target gases were quantified by means of Fourier transform infrared spectrometry (FTIR). The use of biodiesel blend presented lower concentrations in the exhaust fumes than using ultra-low sulfur diesel. NO{sub x} and NO concentrations were 68% to 93% lower in all experiments using SCR, when compared to no exhaust aftertreatment. All fuels increased NH{sub 3} and N{sub 2}O emission due to SCR, a precursor secondary aerosol, and major greenhouse gas, respectively. An AERMOD dispersion model analysis was performed on each compound results for the City of Curitiba, assumed to have a bus fleet equipped with diesel engines and SCR system, in winter and summer seasons. The health risks of the target gases were assessed using the Risk Assessment Information System For 1-h exposure of NH{sub 3}, considering the use of low sulfur diesel in buses equipped with SCR, the results indicated low risk to develop a chronic non-cancer disease. The NO{sub x} and NO emissions were the lowest when SCR was used; however, it yielded the highest NH{sub 3} concentration. The current results have paramount importance, mainly for countries that have not yet adopted the Euro V emission standards like China, India, Australia, or Russia, as well as those already adopting it. These findings are equally important for government agencies to alert the need of improvements in aftertreatment technologies to reduce pollutants emissions. - Highlights: • Emission, dispersion and risk assessment

Understanding NOx emission trends in China based on OMI observations

Science.gov (United States)

Wang, Y.; Ga, D.; Smeltzer, C. D.; Yi, R.; Liu, Z.

2012-12-01

We analyze OMI observations of NO2 columns over China from 2005 to 2010. Simulations using a regional 3-D chemical transport model (REAM) are used to derive the top-down anthropogenic NOx emissions. The Kendall method is then applied to derive the emission trend. The emission trend is affected by the economic slowdown in 2009. After removing the effect of one year abnormal data, the overall emission trend is 4.35±1.42% per year, which is slower than the linear-regression trend of 5.8-10.8% per year reported for previous years. We find large regional, seasonal, and urban-rural variations in emission trend. The annual emission trends of Northeast China, Central China Plain, Yangtze River Delta and Pearl River Delta are 44.98±1.39%, 5.24±1.63%, 3.31±1.02% and -4.02±1.87%, respectively. The annual emission trends of four megacities, Beijing, Shanghai, Guangzhou and Shenzhen are 0.7±0.27%, -0.75±0.31%, -4.08±1.21% and -6.22±2.85%,, considerably lower than the regional averages. These results appear to suggest that a number of factors, including migration of high-emission industries, vehicle emission regulations, emission control measures of thermal power plants, increased hydro-power usage, have reduced or reversed the increasing trend of NOx emissions in more economically developed megacities and southern coastal regions.

Uniformity index measurement technology using thermocouples to improve performance in urea-selective catalytic reduction systems

Science.gov (United States)

Park, Sangki; Oh, Jungmo

2018-05-01

The current commonly used nitrogen oxides (NOx) emission reduction techniques employ hydrocarbons (HCs), urea solutions, and exhaust gas emissions as the reductants. Two of the primary denitrification NOx (DeNOx) catalyst systems are the HC-lean NOx trap (HC-LNT) catalyst and urea-selective catalytic reduction (urea-SCR) catalyst. The secondary injection method depends on the type of injector, injection pressure, atomization, and spraying technique. In addition, the catalyst reaction efficiency is directly affected by the distribution of injectors; hence, the uniformity index (UI) of the reductant is very important and is the basis for system optimization. The UI of the reductant is an indicator of the NOx conversion efficiency (NCE), and good UI values can reduce the need for a catalyst. Therefore, improving the UI can reduce the cost of producing a catalytic converter, which are expensive due to the high prices of the precious metals contained therein. Accordingly, measurement of the UI is an important process in the development of catalytic systems. Two of the commonly used methods for measuring the reductant UI are (i) measuring the exhaust emissions at many points located upstream/downstream of the catalytic converter and (ii) acquisition of a reductant distribution image on a section of the exhaust pipe upstream of the catalytic converter. The purpose of this study is to develop a system and measurement algorithms to measure the exothermic response distribution in the exhaust gas as the reductant passes through the catalytic converter of the SCR catalyst system using a set of thermocouples downstream of the SCR catalyst. The system is used to measure the reductant UI, which is applied in real-time to the actual SCR system, and the results are compared for various types of mixtures for various engine operating conditions and mixer types in terms of NCE.

Highly selective NOx reduction for diesel engine exhaust via an electrochemical system

DEFF Research Database (Denmark)

Shao, Jing; Tao, Youkun; Kammer Hansen, Kent

2016-01-01

It is challenging to reduce the nitrogen oxides (NOx) in diesel engine exhaust due to the inhibiting effect of excess oxygen. In this study, a novel electrochemical deNOx system was developed, which eliminated the need for additional reducing materials or a sophisticated controlling system as used...

Arabidopsis SHR and SCR transcription factors and AUX1 auxin influx carrier control the switch between adventitious rooting and xylogenesis in planta and in in vitro cultured thin cell layers.

Science.gov (United States)

Della Rovere, F; Fattorini, L; D'Angeli, S; Veloccia, A; Del Duca, S; Cai, G; Falasca, G; Altamura, M M

2015-03-01

Adventitious roots (ARs) are essential for vegetative propagation. The Arabidopsis thaliana transcription factors SHORT ROOT (SHR) and SCARECROW (SCR) affect primary/lateral root development, but their involvement in AR formation is uncertain. LAX3 and AUX1 auxin influx carriers contribute to primary/lateral root development. LAX3 expression is regulated by SHR, and LAX3 contributes to AR tip auxin maximum. In contrast, AUX1 involvement in AR development is unknown. Xylogenesis is induced by auxin plus cytokinin as is AR formation, but the genes involved are largely unknown. Stem thin cell layers (TCLs) form ARs and undergo xylogenesis under the same auxin plus cytokinin input. The aim of this research was to investigate SHR, SCR, AUX1 and LAX3 involvement in AR formation and xylogenesis in intact hypocotyls and stem TCLs in arabidopsis. Hypocotyls of scr-1, shr-1, lax3, aux1-21 and lax3/aux1-21 Arabidopsis thaliana null mutant seedlings grown with or without auxin plus cytokinin were examined histologically, as were stem TCLs cultured with auxin plus cytokinin. SCR and AUX1 expression was monitored using pSCR::GFP and AUX1::GUS lines, and LAX3 expression and auxin localization during xylogenesis were monitored by using LAX3::GUS and DR5::GUS lines. AR formation was inhibited in all mutants, except lax3. SCR was expressed in pericycle anticlinally derived AR-forming cells of intact hypocotyls, and in cell clumps forming AR meristemoids of TCLs. The apex was anomalous in shr and scr ARs. In all mutant hypocotyls, the pericycle divided periclinally to produce xylogenesis. Xylary element maturation was favoured by auxin plus cytokinin in shr and aux1-21. Xylogenesis was enhanced in TCLs, and in aux1-21 and shr in particular. AUX1 was expressed before LAX3, i.e. in the early derivatives leading to either ARs or xylogenesis. AR formation and xylogenesis are developmental programmes that are inversely related, but they involve fine-tuning by the same proteins, namely SHR

L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana.

Science.gov (United States)

Wang, Zhen; Mao, Jie-Li; Zhao, Ying-Jun; Li, Chuan-You; Xiang, Cheng-Bin

2015-02-01

L-Cysteine plays a prominent role in sulfur metabolism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PINs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and SCR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth. © 2014 Institute of Botany, Chinese Academy of Sciences.

Top-down NOx and SO2 emissions simultaneously estimated from different OMI retrievals and inversion frameworks

Science.gov (United States)

Qu, Z.; Henze, D. K.; Wang, J.; Xu, X.; Wang, Y.

2017-12-01

Quantifying emissions trends of nitrogen oxides (NOx) and sulfur dioxide (SO2) is important for improving understanding of air pollution and the effectiveness of emission control strategies. We estimate long-term (2005-2016) global (2° x 2.5° resolution) and regional (North America and East Asia at 0.5° x 0.667° resolution) NOx emissions using a recently developed hybrid (mass-balance / 4D-Var) method with GEOS-Chem. NASA standard product and DOMINO retrievals of NO2 column are both used to constrain emissions; comparison of these results provides insight into regions where trends are most robust with respect to retrieval uncertainties, and highlights regions where seemingly significant trends are retrieval-specific. To incorporate chemical interactions among species, we extend our hybrid method to assimilate NO2 and SO2 observations and optimize NOx and SO2 emissions simultaneously. Due to chemical interactions, inclusion of SO2 observations leads to 30% grid-scale differences in posterior NOx emissions compared to those constrained only by NO2 observations. When assimilating and optimizing both species in pseudo observation tests, the sum of the normalized mean squared error (compared to the true emissions) of NOx and SO2 posterior emissions are 54-63% smaller than when observing/constraining a single species. NOx and SO2 emissions are also correlated through the amount of fuel combustion. To incorporate this correlation into the inversion, we optimize seven sector-specific emission scaling factors, including industry, energy, residential, aviation, transportation, shipping and agriculture. We compare posterior emissions from inversions optimizing only species' emissions, only sector-based emissions, and both species' and sector-based emissions. In situ measurements of NOx and SO2 are applied to evaluate the performance of these inversions. The impacts of the inversion on PM2.5 and O3 concentrations and premature deaths are also evaluated.

Marginal abatement cost curves for NOx that account for ...

Science.gov (United States)

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their respective cost effectiveness. Alternative measures, such as renewable electricity, energy efficiency, and fuel switching (RE/EE/FS), are not considered as it is difficult to quantify their abatement potential. In this paper, we demonstrate the use of an energy system model to develop a MACC for nitrogen oxides (NOx) that incorporates both end-of-pipe controls and these alternative measures. We decompose the MACC by sector, and evaluate the cost-effectiveness of RE/EE/FS relative to end-of-pipe controls. RE/EE/FS are shown to produce considerable emission reductions after end-of-pipe controls have been exhausted. Furthermore, some RE/EE/FS are shown to be cost-competitive with end-of-pipe controls. Demonstrate how the MARKAL energy system model can be used to evaluate the potential role of renewable electricity, energy efficiency and fuel switching (RE/EE/FS) in achieving NOx reductions. For this particular analysis, we show that RE/EE/FSs are able to increase the quantity of NOx reductions available for a particular marginal cost (ranging from $5k per ton to $40k per ton) by approximately 50%.

NOx reduction using biomass as reburning fuel

Energy Technology Data Exchange (ETDEWEB)

Niu Sheng-li; Lu Chun-mei; Gao Pan; Han Kui-hua; Geng Ping; Cheng Zhong-jie [Shandong University, Jinan (China). School of Energy and Power Engineering

2008-10-15

A series of experiments were conducted in a multiple-functional combustion test bed with several kinds of biomass as reburning fuel to reduce NOx. The character and experimental parameters are, emphasized to examine the influences on NOx reduction. The results show that biomass could get about 55% to 70% NOx reduction. Within a certain range of the parameters tested, NOx reduction increases with the increasing temperature of reburning zone and initial concentration of NOx and with decreasing excess air ratio and diameter of fuel particle. Under the same test conditions, cornstalk gets the highest NOx reduction and wheat straw, peanut shell, wood chip follow in turn. 14 refs., 7 figs., 1 tab.

SCR series switch and impulse crowbar at the Lawrence Berkeley Laboratory for CTR neutral beam source development

International Nuclear Information System (INIS)

Franck, J.V.; Arthur, A.A.; Brusse, L.A.; Low, W.

1977-10-01

The series switch is designed to operate at 120kV and pass 65A for 0.5 sec every 30 sec on the Lawrence Berkeley Laboratory CTR Neutral Beam Source Test Stand IIIB. The series switch consists of 400 individual SCR circuits connected in series and is turned on by a simple system of cascaded pulse transformers with multiple single turn secondaries each driving the individual SCR gates. It is turned off by an SCR impulse crowbar that momentarily shorts the power supply allowing the series switch to recover. The SCR switch has been tested in the impulse crowbar configuration and will reliably commutate up to 90A at 120kV. The series switch and impulse crowbar are now in service in Test Stand IIIB. A series switch and impulse crowbar similar in concept is routinely powering a 10 x 10 cm source at 150kV, 20A, 0.5 sec with a 1% duty cycle on the Lawrence Berkeley Laboratory CTR NSB Test Stand IIIA

NOx trade. Case studies

International Nuclear Information System (INIS)

Jantzen, J.

2002-01-01

Some of the questions with respect to the trade of nitrogen oxides that businesses in the Netherlands have to deal with are dealt with: should a business buy or sell rights for NOx emission; which measures must be taken to reduce NOx emission; how much must be invested; and how to deal with uncertainties with regard to prices. Simulations were carried out with the MOSES model to find the answers to those questions. Results of some case studies are presented, focusing on the chemical sector in the Netherlands. Finally, the financial (dis)advantages of NOx trade and the related uncertainties for a single enterprise are discussed [nl

Tungsten Recovery from Spent SCR Catalyst Using Alkaline Leaching and Ion Exchange

Directory of Open Access Journals (Sweden)

Wen-Cheng Wu

2016-10-01

Full Text Available The recovery of tungsten (W from a honeycomb-type spent selective catalytic reduction (SCR catalyst using an alkaline leaching–ion exchange method was investigated. Spent SCR catalyst mainly consists of TiO2 and other oxides (6.37% W, 1.57% vanadium (V, and 2.81% silicon (Si, etc.. The ground catalyst was leached at the optimal conditions, as follows: NaOH concentration of 0.3 kg/kg of catalyst, pulp density of 3%, leaching temperature of 70 °C, particle size of −74 μm, and leaching time of 30 min. In this study, the leaching rate values of V and W under the above conditions were 87 wt %, and 91 wt %, respectively. The pregnant solution was then passed through a strong base anion exchange resin (Amberlite IRA900. At high pH conditions, the use of strong base anion exchange resin led to selective loading of divalent WO42− from the solution, because the fraction of two adjacent positively-charged sites on the IRA900 resin was higher and separate from the coexisting VO43−. The adsorbed W could then be eluted with 1 M NaCl + 0.5 M NaOH. The final concentrated W solution had 8.4 g/L of W with 98% purity. The application of this process in industry is expected to have an important impact on the recovery of W from secondary sources of these metals.

NOx Emissions Performance and Correlation Equations for a Multipoint LDI Injector

Science.gov (United States)

He, Zhuohui J.; Chang, Clarence T.; Follen, Caitlin E.

2015-01-01

Lean Direct Injection (LDI) is a combustor concept that reduces nitrogen oxides (NOx) emissions. This paper looks at a 3-zone multipoint LDI concept developed by Parker Hannifin Corporation. The concept was tested in a flame-tube test facility at NASA Glenn Research Center. Due to test facility limitations, such as inlet air temperature and pressure, the flame-tube test was not able to cover the full set of engine operation conditions. Three NOx correlation equations were developed based on assessing NOx emissions dependencies on inlet air pressure (P3), inlet air temperature (T3), and fuel air equivalence ratio (?) to estimate the NOx emissions at the unreachable high engine power conditions. As the results, the NOx emissions are found to be a strong function of combustion inlet air temperature and fuel air equivalence ratio but a weaker function of inlet air pressure. With these three equations, the NOx emissions performance of this injector concept is calculated as a 66% reduction relative to the ICAO CAEP-6 standard using a 55:1 pressure-ratio engine cycle. Uncertainty in the NOx emissions estimation increases as the extrapolation range departs from the experimental conditions. Since maximum inlet air pressure tested was less than 50% of the full power engine inlet air pressure, a future experiment at higher inlet air pressure conditions is needed to confirm the NOx emissions dependency on inlet air pressure.

Standing on the shoulders of giants

Energy Technology Data Exchange (ETDEWEB)

Ellis, B.; Lacey, M. [Cinergy-PSI, Owensville, IN (United States)

2002-07-01

Retrofitting SCR plant 230 feet above the Gibson power station near Evansville in Southern Indiana in the USA requires a titanic effort physically and logistically, involving the world's biggest tower crane at the USA's second biggest coal fired plant. The article describes how the SCR option was decided upon and outlines progress of the project to date. As of April 2002 the project was 50% complete. Unit 2 SCR had been tested at design (85%) NOx reduction whilst Unit 3 SCR is in the advanced stages of commissioning. 2 figs., 1 tab.

O3 and NOx Exchange

NARCIS (Netherlands)

Loubet, B.; Castell, J.F.; Laville, P.; Personne, E.; Tuzet, A.; Ammann, C.; Emberson, L.; Ganzeveld, L.; Kowalski, A.S.; Merbold, L.; Stella, P.; Tuovinen, J.P.

2015-01-01

This discussion was based on the background document “Review on modelling atmosphere-biosphere exchange of Ozone and Nitrogen oxides”, which reviews the processes contributing to biosphere-atmosphere exchange of O3 and NOx, including stomatal and non-stomatal exchange of O3 and NO, NO2.

Geopolymer based catalysts-New group of catalytic materials

Czech Academy of Sciences Publication Activity Database

Sazama, Petr; Bortnovsky, O.; Dědeček, Jiří; Tvarůžková, Zdenka; Sobalík, Zdeněk

2011-01-01

Roč. 164, č. 1 (2011), s. 92-99 ISSN 0920-5861. [Joint International Conference /1./ of the Tokyo Conference on Advanced Catalytic Science and Technology /11./ Asia Pacific Congress on Catalysis /5./. Sapporo, 18.07.2010-23.07.2010] R&D Projects: GA MPO FT-TA4/068; GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : geopolymers * redox catalysis * SCR-NOx Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

RETROFIT COSTS FOR SO2 AND NOX CONTROL OPTIONS AT 200 COAL-FIRED PLANTS, VOLUME I - INTRODUCTION AND METHODOLOGY

Science.gov (United States)

The report gives results of a study, the objective of which was to significantly improve engineering cost estimates currently being used to evaluate the economic effects of applying SO2 and NOx controls at 200 large SO2-emitting coal-fired utility plants. To accomplish the object...

NOx PREDICTION FOR FBC BOILERS USING EMPIRICAL MODELS

Directory of Open Access Journals (Sweden)

Jiří Štefanica

2014-02-01

Full Text Available Reliable prediction of NOx emissions can provide useful information for boiler design and fuel selection. Recently used kinetic prediction models for FBC boilers are overly complex and require large computing capacity. Even so, there are many uncertainties in the case of FBC boilers. An empirical modeling approach for NOx prediction has been used exclusively for PCC boilers. No reference is available for modifying this method for FBC conditions. This paper presents possible advantages of empirical modeling based prediction of NOx emissions for FBC boilers, together with a discussion of its limitations. Empirical models are reviewed, and are applied to operation data from FBC boilers used for combusting Czech lignite coal or coal-biomass mixtures. Modifications to the model are proposed in accordance with theoretical knowledge and prediction accuracy.

Storage of Nitrous Oxide (NOx in Diesel Engine Exhaust Gas using Alumina-Based Catalysts: Preparation, Characterization, and Testing

Directory of Open Access Journals (Sweden)

A. Alsobaai

2017-03-01

Full Text Available This work investigated the nitrous oxide (NOx storage process using alumina-based catalysts (K2 O/Al2 O3 , CaO/Al2 O3,  and BaO/Al2 O3 . The feed was a synthetic exhaust gas containing 1,000 ppm of nitrogen monoxide (NO, 1,000 ppm i-C4 H10 , and an 8% O2  and N2  balance. The catalyst was carried out at temperatures between 250–450°C and a contact time of 20 minutes. It was found that NOx was effectively adsorbed in the presence of oxygen. The NOx storage capacity of K2 O/Al2 O3 was higher than that of BaO/Al2 O3.  The NOx storage capacity for K2 O/Al2 O3  decreased with increasing temperature and achieved a maximum at 250°C. Potassium loading higher than 15% in the catalyst negatively affected the morphological properties. The combination of Ba and K loading in the catalyst led to an improvement in the catalytic activity compared to its single metal catalysts. As a conclusion, mixed metal oxide was a potential catalyst for de-NOx process in meeting the stringent diesel engine exhaust emissions regulations. The catalysts were characterized by a number of techniques and measurements, such as X-ray diffraction (XRD, electron affinity (EA, a scanning electron microscope (SEM, Brunner-Emmett-Teller (BET to measure surface area, and pore volume and pore size distribution assessments.

Major issues in the design and construction of the stellarator of Costa Rica: SCR-1

International Nuclear Information System (INIS)

Mora, J; Vargas, V I; Villegas, L F; Barillas, L; Monge, J I; Rivas, L

2012-01-01

This paper aims at briefly describing the design and construction issues of the stellarator of Costa Rica 1 (SCR-1). The SCR-1 is a small modular Stellarator for magnetic confinement of plasma developed by the Plasma Physics Group of the Instituto Tecnologico de Costa Rica (ITCR). The SCR-1 is based on the small Spanish Stellarator UST 1 (Ultra Small Torus 1), created by Eng. Vicente Queral. These mains issues consist of the size of the Stellarator, closeness between coils, coupling of ECH to the vacuum chamber and the device for support. The size has become a problem because the vacuum chamber does not allow a lot of space to attach diagnosis devices, the heating system, the vacuum system and the very same support of the chamber. As a result of this lack of space, the Stellarator's coils are placed very close to each other; this means that two of the coils around of the vacuum chamber clash and cannot be placed as designed. The issue regarding the coupling of the ECH (electron cyclotron radio-frequency) to the vacuum chamber comprises the fact that the wave guide with rectangular shape does not match the CF port with circular shape on the vacuum chamber. In addition, the device for supporting the Stellarator has presented a challenge because of its size and the placement of the coils; in other words, there is not enough space between the ports and coils in the Stellarator to place appropriately the device for support.

NOx Emissions from Diesel Passenger Cars Worsen with Age.

Science.gov (United States)

Chen, Yuche; Borken-Kleefeld, Jens

2016-04-05

Commonly, the NOx emissions rates of diesel vehicles have been assumed to remain stable over the vehicle's lifetime. However, there have been hardly any representative long-term emission measurements. Here we present real-driving emissions of diesel cars and light commercial vehicles sampled on-road over 15 years in Zurich/Switzerland. Results suggest deterioration of NOx unit emissions for Euro 2 and Euro 3 diesel technologies, while Euro 1 and Euro 4 technologies seem to be stable. We can exclude a significant influence of high-emitting vehicles. NOx emissions from all cars and light commercial vehicles in European emission inventories increase by 5-10% accounting for the observed deterioration, depending on the country and its share of diesel cars. We suggest monitoring the stability of emission controls particularly for high-mileage light commercial as well as heavy-duty vehicles.

Bromine based mercury abatement in waste and coal combustion. Mercury retention in the catalyst bed of a tail-end-SCR

Energy Technology Data Exchange (ETDEWEB)

Vosteen, Bernhard W. [Vosteen Consulting GmbH, Koeln (Germany); Kanefke, Rico; Beyer, Joachim; Bonkhofer, Theodor Gerhard [CURRENTA GmbH und Co. OHG, Leverkusen (Germany); Ullrich, Rick [WastePro Engineering Inc., Kennett Square, PA (United States)

2008-07-01

Observations and testing at a CURRENTA waste incineration plant and several coal fired power plants has derived the following aspects of mercury behavior in the plant's waste heat boiler and its gas cleaning train: - Hg{sub met} is oxidized to Hg{sub ion} most readily by bromine, and also by chlorine, - sulfur (SO{sub 2}) inhibit the Hg{sub met} chlorination but not the Hg{sub met} bromination, - Hg{sub met} passes through scrubbers and is adsorbed onto the catalyst bed of a tail-end SCR, slowly oxidized and finally elutes off as Hg{sub ion}, - sulfur (SO{sub 2}) impacts the reduction of molecular halogens in different ways; SO{sub 2} reduces Cl{sub 2} at elevated temperatures (boiler range), but reduces Br{sub 2} only at low temperatures (scrubber range) The operational tests and studies performed in the spring and summer of 2000 at this plant led to some specific knowledge about Hg{sub met} adsorption and also Hg{sub ion} desorption at the catalyst bed of a tail-end SCR. This knowledge, which was at that time in many respects novel, has provided more insight into the mercury oxidation behaviour. Today, process options derived from this knowledge could be implemented in hazardous waste incineration plants and also municipal solid waste incineration plants, to achieve complete mercury halogenation in the boiler flue gas, ahead of the scrubber system, at any time. This might prevent penetration of metallic mercury to the tail-end SCR and avoid the corresponding long time mercury elution. For effective prevention to be achieved in practice, it is strongly recommended to also install a continuously measuring (possibly uncalibrated) AAS mercury monitor for immediate detection of any unexpected Hg{sub met} breakthrough, for example caused by ''hidden mercury'' in the waste feed, and to initiate the rapid (preferably automized) injection of some bromine compound before even more mercury is transferred into the tail-end SCR, stored there as Hg

Recombinant Nox4 cytosolic domain produced by a cell or cell-free base systems exhibits constitutive diaphorase activity

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Minh Vu Chuong, E-mail: mvchuong@yahoo.fr [GREPI AGIM FRE 3405 CNRS-UJF, Universite Joseph Fourier, Grenoble (France); Zhang, Leilei [GREPI AGIM FRE 3405 CNRS-UJF, Universite Joseph Fourier, Grenoble (France); Lhomme, Stanislas; Mouz, Nicolas [PX' Therapeutics, MINATEC/Batiment de Haute Technologie, Grenoble (France); Lenormand, Jean-Luc [HumProTher Laboratory, TheReX/TIMC-IMAG UMR 5525 CNRS UJF, Universite Joseph Fourier, UFR de Medecine, Domaine de la Merci, 38706 La Tronche (France); Lardy, Bernard; Morel, Francoise [GREPI AGIM FRE 3405 CNRS-UJF, Universite Joseph Fourier, Grenoble (France)

2012-03-16

Highlights: Black-Right-Pointing-Pointer A comparison of two bacterial cell and cell-free protein expression systems is presented. Black-Right-Pointing-Pointer Soluble and active truncated Nox4 proteins are produced. Black-Right-Pointing-Pointer Nox4 has a constitutive diaphorase activity which is independent of cytosolic factors. Black-Right-Pointing-Pointer Isoform Nox4B is unable to initiate the first electronic transfer step. Black-Right-Pointing-Pointer Findings contribute to the understanding of the mechanism of Nox4 oxidase activity. -- Abstract: The membrane protein NADPH (nicotinamide adenine dinucleotide phosphate) oxidase Nox4 constitutively generates reactive oxygen species differing from other NADPH oxidases activity, particularly in Nox2 which needs a stimulus to be active. Although the precise mechanism of production of reactive oxygen species by Nox2 is well characterized, the electronic transfer throughout Nox4 remains unclear. Our study aims to investigate the initial electronic transfer step (diaphorase activity) of the cytosolic tail of Nox4. For this purpose, we developed two different approaches to produce soluble and active truncated Nox4 proteins. We synthesized soluble recombinant proteins either by in vitro translation or by bacteria induction. While proteins obtained by bacteria induction demonstrate an activity of 4.4 {+-} 1.7 nmol/min/nmol when measured against iodonitro tetrazolium chloride and 20.5 {+-} 2.8 nmol/min/nmol with cytochrome c, the soluble proteins produced by cell-free expression system exhibit a diaphorase activity with a turn-over of 26 {+-} 2.6 nmol/min/nmol when measured against iodonitro tetrazolium chloride and 48 {+-} 20.2 nmol/min/nmol with cytochrome c. Furthermore, the activity of the soluble proteins is constitutive and does not need any stimulus. We also show that the cytosolic tail of the isoform Nox4B lacking the first NADPH binding site is unable to demonstrate any diaphorase activity pointing out the

Solid State Electrochemical DeNOx

DEFF Research Database (Denmark)

Kammer Hansen, Kent

2010-01-01

The literature on direct electrochemical reduction of NOx in a solid state cell has been reviewed. It is shown that that the reduction of nitric oxide either occurs on the electrode or on the electrolyte if F-centers are formed. It is also shown that some oxide based electrodes has a high apparent...

Worldwide biogenic soil NOx emissions inferred from OMI NO2 observations

NARCIS (Netherlands)

Vinken, G.C.M.; Boersma, K.F.; Maasakkers, J.D.; Adon, M.; Martin, R.V.

2014-01-01

Biogenic NOx emissions from soils are a large natural source with substantial uncertainties in global bottom-up estimates (ranging from 4 to 15 Tg N yr-1). We reduce this range in emission estimates, and present a top-down soil NOx emission inventory for 2005 based on retrieved tropospheric NO2

Worldwide biogenic soil NOx emissions inferred from OMI NO2 observations.

NARCIS (Netherlands)

Vinken, G.C.M.; Boersma, K.F.; Maasakkers, J.D.; Adon, M.; Martin, R.V.

2014-01-01

Biogenic NOx emissions from soils are a large natural source with substantial uncertainties in global bottom-up estimates (ranging from 4 to 15 Tg N yr-1). We reduce this range in emission estimates, and present a top-down soil NOx emission inventory for 2005 based on retrieved tropospheric NO2

Experimental study on removals of SO2 and NO(x) using adsorption of activated carbon/microwave desorption.

Science.gov (United States)

Ma, Shuang-Chen; Yao, Juan-Juan; Gao, Li; Ma, Xiao-Ying; Zhao, Yi

2012-09-01

Experimental studies on desulfurization and denitrification were carried out using activated carbon irradiated by microwave. The influences of the concentrations of nitric oxide (NO) and sulfur dioxide (SO2), the flue gas coexisting compositions, on adsorption properties of activated carbon and efficiencies of desulfurization and denitrification were investigated. The results show that adsorption capacity and removal efficiency of NO decrease with the increasing of SO2 concentrations in flue gas; adsorption capacity of NO increases slightly first and drops to 12.79 mg/g, and desulfurization efficiency descends with the increasing SO2 concentrations. Adsorption capacity of SO2 declines with the increasing of O2 content in flue gas, but adsorption capacity of NO increases, and removal efficiencies of NO and SO2 could be larger than 99%. Adsorption capacity of NO declines with the increase of moisture in the flue gas, but adsorption capacity of SO2 increases and removal efficiencies of NO and SO2 would be relatively stable. Adsorption capacities of both NO and SO2 decrease with the increasing of CO2 content; efficiencies of desulfurization and denitrification augment at the beginning stage, then start to fall when CO2 content exceeds 12.4%. The mechanisms of this process are also discussed. The prominent SO2 and NOx treatment techniques in power plants are wet flue gas desulfurization (FGD) and the catalytic decomposition method like selective catalytic reduction (SCR) or nonselective catalytic reduction (NSCR). However, these processes would have some difficulties in commercial application due to their high investment, requirement of expensive catalysts and large-scale equipment, and so on. A simple SO2 and NOx reduction utilizing decomposition by microwave energy method can be used. The pollutants control of flue gas in the power plants by the method of microwave-induced decomposition using adsorption of activated carbon/microwave desorption can meet the

Influence of satellite-derived photolysis rates and NOx emissions on Texas ozone modeling

Science.gov (United States)

Tang, W.; Cohan, D. S.; Pour-Biazar, A.; Lamsal, L. N.; White, A. T.; Xiao, X.; Zhou, W.; Henderson, B. H.; Lash, B. F.

2015-02-01

Uncertain photolysis rates and emission inventory impair the accuracy of state-level ozone (O3) regulatory modeling. Past studies have separately used satellite-observed clouds to correct the model-predicted photolysis rates, or satellite-constrained top-down NOx emissions to identify and reduce uncertainties in bottom-up NOx emissions. However, the joint application of multiple satellite-derived model inputs to improve O3 state implementation plan (SIP) modeling has rarely been explored. In this study, Geostationary Operational Environmental Satellite (GOES) observations of clouds are applied to derive the photolysis rates, replacing those used in Texas SIP modeling. This changes modeled O3 concentrations by up to 80 ppb and improves O3 simulations by reducing modeled normalized mean bias (NMB) and normalized mean error (NME) by up to 0.1. A sector-based discrete Kalman filter (DKF) inversion approach is incorporated with the Comprehensive Air Quality Model with extensions (CAMx)-decoupled direct method (DDM) model to adjust Texas NOx emissions using a high-resolution Ozone Monitoring Instrument (OMI) NO2 product. The discrepancy between OMI and CAMx NO2 vertical column densities (VCDs) is further reduced by increasing modeled NOx lifetime and adding an artificial amount of NO2 in the upper troposphere. The region-based DKF inversion suggests increasing NOx emissions by 10-50% in most regions, deteriorating the model performance in predicting ground NO2 and O3, while the sector-based DKF inversion tends to scale down area and nonroad NOx emissions by 50%, leading to a 2-5 ppb decrease in ground 8 h O3 predictions. Model performance in simulating ground NO2 and O3 are improved using sector-based inversion-constrained NOx emissions, with 0.25 and 0.04 reductions in NMBs and 0.13 and 0.04 reductions in NMEs, respectively. Using both GOES-derived photolysis rates and OMI-constrained NOx emissions together reduces modeled NMB and NME by 0.05, increases the model

A new 3DOM Ce-Fe-Ti material for simultaneously catalytic removal of PM and NOx from diesel engines.

Science.gov (United States)

Cheng, Ying; Liu, Jian; Zhao, Zhen; Song, Weiyu; Wei, Yuechang

2018-01-15

A new 3DOM material was designed and synthesized for the simultaneous removal of PM (soot particulates) and NOx from diesel engine exhausts. The catalytic purification taking place over the material with double efficacy is cost-efficient. The contact between solid PM and catalyst active site has been process intensified by 3DOM unique structure. 3DOM Ce 0.7 Fe 0.2 Ti 0.1 O 2 catalyst possess a high SCR activity and an excellent selectivity to N 2 , giving a maximum concentration of CO 2 at 385°C for PM combustion and 100% NO conversion in the temperature range of 281-425°C. The dual redox cycles (Fe 3+ +Ce 3+ ↔Fe 2+ +Ce 4+ ,Fe 3+ +Ti 3+ ↔Fe 2+ +Ti 4+ ) and the excellent reducibility and sufficient acid sites of catalysts play key roles for the highly catalytic performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Myocardin-related transcription factor regulates Nox4 protein expression

DEFF Research Database (Denmark)

Rozycki, Matthew; Bialik, Janne Folke; Speight, Pam

2016-01-01

translocation of MRTF. Because the Nox4 promoter harbors a serum response factor/MRTF cis-element (CC(A/T)6GG box), we asked if MRTF (and thus cytoskeleton organization) could regulate Nox4 expression. We show that Nox4 protein is robustly induced in kidney tubular cells exclusively by combined application...... TGFβ/contact disruption-provoked Nox4 protein and mRNA expression, Nox4 promoter activation, and reactive oxygen species production. Mutation of the CC(A/T)6GG box eliminates the synergistic activation of the Nox4 promoter. Jasplakinolide-induced actin polymerization synergizes with TGFβ to facilitate...... MRTF-dependent Nox4 mRNA expression/promoter activation. Moreover, MRTF inhibition prevents Nox4 expression during TGFβ-induced fibroblast-myofibroblast transition as well. Although necessary, MRTF is insufficient; Nox4 expression also requires TGFβ-activated Smad3 and TAZ/YAP, two contact...

Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

Energy Technology Data Exchange (ETDEWEB)

Nigel N. Clark

2006-12-31

, with added EGR to prevent preignition. It was observed that the relative air/fuel ratio, injected NO quantity, added EGR fraction, and engine operating points affected the NO decomposition rates. While operating under these modified conditions, the highest NO decomposition rate of 92% was observed. In-cylinder pressure data gathered during the experiments showed minimum deviation from peak pressure as a result of NO injections into the engine. A NOx adsorption system, from Sorbent Technologies, Inc., was integrated with the Cummins engine, comprised a NOx adsorbent chamber, heat exchanger, demister, and a hot air blower. Data were gathered to show the possibility of NOx adsorption from the engine exhaust, and desorption of NOx from the sorbent material. In order to quantify the NOx adsorption/desorption characteristics of the sorbent material, a benchtop adsorption system was constructed. The temperature of this apparatus was controlled while data were gathered on the characteristics of the sorbent material for development of a system model. A simplified linear driving force model was developed to predict NOx adsorption into the sorbent material as cooled exhaust passed over fresh sorbent material. A mass heat transfer analysis was conducted to analyze the possibility of using hot exhaust gas for the desorption process. It was found in the adsorption studies, and through literature review, that NO adsorption was poor when the carrier gas was nitrogen, but that NO in the presence of oxygen was adsorbed at levels exceeding 1% by mass of the sorbent. From the three experimental campaigns, chemical kinetic modeling analysis, and the scaled benchtop NOx adsorption system, an overall SNR system model was developed. An economic analysis was completed, and showed that the system was impractical in cost for small engines, but that economies of scale favored the technology.

TGF-β1-induced cell migration in pancreatic carcinoma cells is RAC1 and NOX4-dependent and requires RAC1 and NOX4-dependent activation of p38 MAPK.

Science.gov (United States)

Witte, David; Bartscht, Tobias; Kaufmann, Roland; Pries, Ralph; Settmacher, Utz; Lehnert, Hendrik; Ungefroren, Hendrik

2017-12-01

Transforming growth factor (TGF)-β promotes epithelial-mesenchymal transition and cell invasion of cancer cells in part through the small GTPase RAC1. Since RAC1 can signal through reactive oxygen species (ROS), we probed the role of the ROS-producing NADPH oxidase (NOX) and p38 mitogen-activated protein kinase (MAPK) in mediating TGF-β1/RAC1-driven random cell migration (chemokinesis). Although the NOX isoforms NOX2, 4, 5, 6, and RAC1 were readily detectable by RT-PCR in pancreatic ductal adenocarcinoma (PDAC)-derived Panc1 and Colo357 cells, only NOX4 and RAC1 were expressed at higher levels comparable to those in peripheral blood monocytes. TGF-β1 treatment resulted in upregulation of NOX4 (and NOX2) and rapid intracellular production of ROS. To analyze whether RAC1 functions through NOX and ROS to promote cell motility, we performed real-time cell migration assays with xCELLigence® technology in the presence of the ROS scavenger N-acetyl-L-cysteine (NAC) and various NOX inhibitors. NAC, the NOX4 inhibitor diphenylene iodonium or small interfering RNA (siRNA) to NOX4, and the NOX2 inhibitor apocynin all suppressed TGF-β1-induced chemokinesis of Panc1 and Colo357 cells as did various inhibitors of RAC1 used as control. In addition, we showed that blocking NOX4 or RAC1 function abrogated phosphorylation of p38 MAPK signaling by TGF-β1 and that inhibition of p38 MAPK reduced TGF-β1-induced random cell migration, while ectopic expression of a kinase-active version of the p38 activating kinase MKK6 was able to partially rescue the decline in migration after RAC1 inhibition. Our data suggest that TGF-β1-induced chemokinesis in PDAC cells is mediated through a RAC1/NOX4/ROS/p38 MAPK cascade.

5th international exhaust gas and particulate emissions forum. Proceedings; 5. Internationales Forum Abgas- und Partikelemissionen. Beitraege

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-12-11

The Proceedings of the 5th International Exhaust Gas and Particulate Emissions Forum contains 22 printed contributions as well as a CD-ROM. The titles of them are: (1) Diesel Emissions Control in the United States - 2010 and Beyond; (2) The MBE90 commercial vehicle engine for EPA '07 emissions regulations; (3) Concepts for engines and exhaust-gas cleaning systems for heavy duty trucks of the future; (4) HD Engine Technology for Near-Zero Emissions and Lowest Cost of Ownership; (5) (Partially-) Homogeneous Diesel Combustion; (6) Exhaust gas sensors for NOx storage catalysts and ammonia-SCR systems; (7) Sensors for modern exhaust gas after-treatment systems; (8) New reducing agents for low NOx-SCR Techno-logy; (9) Exhaust gas Aftertreatment on Lean Burn Gasoline Direct Injection Engines: The System of TWC and NOx-Storage Catalyst; (10) New Platinum/Palladium based catalyzed filter technologies for future passenger car applications; (11) Development of a Roadway Hydrocarbon Sorption Model and Characterization of a Novel PM Generator; (12) Requirements for current and future particulate measurement instrumentation from the point of view of the Physikalisch-Technische Bundesanstalt; (13) Standardized dilution conditions for gravimetric PM sampling - measures to assure results that correlate; (14) Particle Counting according PMP; (15) Future high-confidence measurement of diesel particulate emissions for approval and development; (16) New developments in optical instrumentation for exhaust gas; (17) Simultaneous Detection of Gaseous and Particulate Exhaust Components by Photoacoustic Spectroscopy; (18) Boundaries of modern exhaust gas instrumentation; (19) Raising quality and reducing application effort through efficient data input to the particulate filter load model for a EURO5 diesel car; (20) Stop-start operation of diesel engines - modified require-ment for exhaust gas after-treatment?; (21) Particulates emission with Biodiesel B30 impact on CSF management; (22

5th international exhaust gas and particulate emissions forum. Proceedings; 5. Internationales Forum Abgas- und Partikelemissionen. Beitraege

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-12-11

The Proceedings of the 5th International Exhaust Gas and Particulate Emissions Forum contains 22 printed contributions as well as a CD-ROM. The titles of them are: (1) Diesel Emissions Control in the United States - 2010 and Beyond; (2) The MBE90 commercial vehicle engine for EPA '07 emissions regulations; (3) Concepts for engines and exhaust-gas cleaning systems for heavy duty trucks of the future; (4) HD Engine Technology for Near-Zero Emissions and Lowest Cost of Ownership; (5) (Partially-) Homogeneous Diesel Combustion; (6) Exhaust gas sensors for NOx storage catalysts and ammonia-SCR systems; (7) Sensors for modern exhaust gas after-treatment systems; (8) New reducing agents for low NOx-SCR Techno-logy; (9) Exhaust gas Aftertreatment on Lean Burn Gasoline Direct Injection Engines: The System of TWC and NOx-Storage Catalyst; (10) New Platinum/Palladium based catalyzed filter technologies for future passenger car applications; (11) Development of a Roadway Hydrocarbon Sorption Model and Characterization of a Novel PM Generator; (12) Requirements for current and future particulate measurement instrumentation from the point of view of the Physikalisch-Technische Bundesanstalt; (13) Standardized dilution conditions for gravimetric PM sampling - measures to assure results that correlate; (14) Particle Counting according PMP; (15) Future high-confidence measurement of diesel particulate emissions for approval and development; (16) New developments in optical instrumentation for exhaust gas; (17) Simultaneous Detection of Gaseous and Particulate Exhaust Components by Photoacoustic Spectroscopy; (18) Boundaries of modern exhaust gas instrumentation; (19) Raising quality and reducing application effort through efficient data input to the particulate filter load model for a EURO5 diesel car; (20) Stop-start operation of diesel engines - modified require-ment for exhaust gas after-treatment?; (21) Particulates emission with Biodiesel B30 impact on CSF management; (22

NOx and SO2 emission factors for Serbian lignite Kolubara

Directory of Open Access Journals (Sweden)

Jovanović Vladimir V.

2012-01-01

Full Text Available Emission factors are widely accepted tool for estimation of various pollutants emissions in USA and EU. Validity of emission factors is strongly related to experimental data on which they are based. This paper is a result of an effort to establish reliable NOx and SO2 emission factors for Serbian coals. The results of NOx and SO2 emissions estimations based on USA and EU emission factors from thermal power plants Nikola Tesla Obrenovac A and B utilizing the Serbian lignite Kolubara are compared with experimental data obtained during almost one decade (2000-2008 of emissions measurements. Experimental data are provided from regular annual emissions measurement along with operational parameters of the boiler and coal (lignite Kolubara ultimate and proximate analysis. Significant deviations of estimated from experimental data were observed for NOx, while the results for SO2 were satisfactory. Afterwards, the estimated and experimental data were plotted and linear regression between them established. Single parameter optimization was performed targeting the ideal slope of the regression line. Results of this optimization provided original NOx and SO2 emission factors for Kolubara lignite.

PM, NOx and butane emissions from on-road vehicle fleets in Hong Kong and their implications on emission control policy

Science.gov (United States)

Ning, Zhi; Wubulihairen, Maimaitireyimu; Yang, Fenhuan

2012-12-01

Vehicular emissions are the major sources of air pollution in urban areas. For metropolitan cities with large population working and living in environments with direct traffic impact, emission control is of great significance to protect public health. Implementation of more stringent emission standards, retrofitting fleet with emission control devices and switching to clearer fuel has been commonly practiced in different cities including Hong Kong. The present study employed a new plume chasing method for effective and quick evaluation of on-road fleet emission factors of particulate matter (PM), nitrogen oxides (NOx), and butane from heavy duty diesel trucks, diesel buses and liquefied petroleum gas (LPG) vehicles. The results showed distinct profiles of the emissions from different fleets with excessive butane emissions from LPG fleet and contrasting PM and NOx emissions from diesel trucks and buses fleets. A cross comparison was also made with emission data from other cities and from historic local studies. The implications of the observed difference on the effectiveness of emission control measures and policy are discussed with recommendations of direction for future research and policy making.

A fuzzy logic urea dosage controller design for two-cell selective catalytic reduction systems.

Science.gov (United States)

You, Kun; Wei, Lijiang; Jiang, Kai

2017-12-22

Diesel engines have dominated in the heavy-duty vehicular and marine power source. However, the induced air pollution is a big problem. As people's awareness of environmental protection increasing, the emission regulations of diesel-engine are becoming more stringent. In order to achieve the emission regulations, the after-treatment system is a necessary choice. Specifically, the selective catalytic reduction (SCR) system has been widely applied to reduce the NO X emissions of diesel engine. Different from single-cell SCR systems, the two-cell systems have various benefits from the modeling and control perspective. In this paper, the urea dosage controller design for two-cell SCR systems was investigated. Firstly, the two-cell SCR modeling was introduced. Based on the developed model, the design procedure for the fuzzy logic urea dosage controller was well addressed. Secondly, simulations and comparisons were employed via an experimental verification of the whole vehicle simulator. And the results showed that the designed controller simultaneously achieved high NO X reduction rate and low tail-pipe ammonia slip. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

OVERVIEW OF ADVANCED PETROLEUM-BASED FUELS-DIESEL EMISSIONS CONTROL PROGRAM (APBF-DEC)

Energy Technology Data Exchange (ETDEWEB)

Sverdrup, George M.

2000-08-20

The Advanced Petroleum-Based Fuels-Diesel Emissions Control Program (APBF-DEC) began in February 2000 and is supported by government agencies and industry. The purpose of the APBF-DEC program is to identify and evaluate the optimal combinations of fuels, lubricants, diesel engines, and emission control systems to meet the projected emission standards for the 2000 to 2010 time period. APBF-DEC is an outgrowth of the earlier Diesel Emission Control-Sulfur Effects Program (DECSE), whose objective is to determine the impact of the sulfur levels in fuel on emission control systems that could lower the emissions of NOx and particulate matter (PM) from diesel powered vehicles in the 2002 to 2004 period. Results from the DECSE studies of two emission control technologies-diesel particle filter (DPF) and NOx adsorber-will be used in the APBF-DEC program. These data are expected to provide initial information on emission control technology options and the effects of fuel properties (including additives) on the performance of emission control systems.

Dexamethasone Modifies Cystatin C-Based Diagnosis of Acute Kidney Injury During Cisplatin-Based Chemotherapy

Directory of Open Access Journals (Sweden)

Timothy J. Pianta

2017-03-01

Full Text Available Background/Aims: Plasma cystatin C (pCysC may be superior to serum creatinine (sCr as a surrogate of GFR. However, the performance of pCysC for diagnosing acute kidney injury (AKI after cisplatin-based chemotherapy is potentially affected by accompanying corticosteroid anti-emetic therapy and hydration. Methods: In a prospective observational study pCysC, sCr, urinary kidney injury molecule-1 (KIM-1, and urinary clusterin were measured over 2 weeks in 27 patients given first-cycle chemotherapy. The same variables were measured over 2 weeks in Sprague–Dawley rats given a single intraperitoneal injection of dexamethasone, cisplatin, or both, and in controls. Results: In patients, pCysC increases were greater than sCr 41% vs. 16%, mean paired difference 25% (95% CI: 16–34%], relative increases were ≥ 50% in 9 patients (35% for pCysC compared with 2 (8% for sCr (p = 0.04 and increases in sCr were accompanied by increased KIM-1 and clusterin excretion, but increases in pCysC alone were not. In rats, dexamethasone administration produced dose-dependent increases in pCysC (and augmented cisplatin-induced increases in pCysC, but did not augment histological injury, increases in sCr, or KIM-1 and clusterin excretion. Conclusions: In the presence of dexamethasone, elevation of pCysC does not reliably diagnose AKI after cisplatin-based chemotherapy.

Estimation of Kinetic Parameters in an Automotive SCR Catalyst Model

DEFF Research Database (Denmark)

Åberg, Andreas; Widd, Anders; Abildskov, Jens

2016-01-01

be used directly for accurate full-scale transient simulations. The model was validated against full-scale data with an engine following the European Transient Cycle. The validation showed that the predictive capability for nitrogen oxides (NOx) was satisfactory. After re-estimation of the adsorption...... and desorption parameters with full-scale transient data, the fit for both NOx and NH3-slip was satisfactory....

Modeling of nitrogen oxides (NO(x)) concentrations resulting from ships at berth.

Science.gov (United States)

Abdul-Wahab, Sabah A; Elkamel, Ali; Al Balushi, Abdullah S; Al-Damkhi, Ali M; Siddiqui, Rafiq A

2008-12-01

Oxides of nitrogen (NO(x)) emissions from ships (marine vessels) contribute to poor air quality that negatively impacts public health and communities in coastal areas and far inland. These emissions often excessively harm human health, environment, wildlife habituates, and quality of life of communities and indigenous of people who live near ports. This study was conducted to assess the impact of NO(x) emissions origination from ships at berth on a nearby community. It was undertaken at Said Bin Sultan Naval base in Wullayat Al-Mussana (Sultanate of Oman) during the year 2005. The Industrial Source Complex Short Term (ISCST) model was adopted to determine the dispersion of NO(x) into port and beyond into surrounding urban areas. The hourly and monthly contours (isopleths) of NO(x) concentrations in and around the port were plotted. The results were analyzed to determine the affected area and the level of NO(x) concentrations. The highest concentration points in the studied area were also identified. The isopleths of NO(x) indicated that most shipping emissions of NO(x) occur at the port can be transported over land. The output results can help to derive advice of recommendations ships operators and environmentalists to take the correct decision to prevent workers and surrounded environment from pollution.

Numerical simulation of flow in De-NOx catalyst honeycomb with NOx reduction reaction

Energy Technology Data Exchange (ETDEWEB)

Tanno, K.; Makino, H. [Electric Power Industry, Kanagawa (Japan). Energy Engineering Research Lab.; Kurose, R.; Komori, S. [Kyoto Univ. (Japan). Dept. of Mechanical Engineering and Science

2013-07-01

The effect of flow behavior in a De-NOx honeycomb with NOx reduction reaction is investigated by direct numerical simulation (DNS). As the inlet flow, fully developed turbulent or laminar flow is given. The results show that the surface reaction is strongly affected by inner flow behavior. The surface reaction rate for the turbulent flow is higher than that for the laminar flow. This is due to the difference of inner flow behavior that the diffusion of NOx in the vicinity of the wall is dominated only by molecular diffusion for the laminar flow, whereas it is enhanced by turbulent motions for the turbulent flow. Moreover, surface reaction is suppressed towards downstream even though inlet flow is turbulent. This is due to the flow transition from turbulent to laminar.

Preliminary thermodynamic study of regenerative Otto based cycles with zero NOx emissions operating with adiabatic and polytropic expansion

International Nuclear Information System (INIS)

Garcia, Ramon Ferreiro; Carril, Jose Carbia; Romero Gomez, Javier; Romero Gomez, Manuel

2016-01-01

Highlights: • Efficient polytropic expansion based Otto cycle. • Thermal efficiency is due to the inherent regeneration. • Low temperature combustion with zero NOx emissions. - Abstract: The aim of the paper is to demonstrate that a regenerative Otto cycle with adiabatic or polytropic expansion can achieve improved performance over traditional Otto engines, even exceeding the Carnot factor. Thus, the work deals with a novel regenerative Otto based internal combustion engine which differs from the conventional Otto thermal cycles in that the process of heat conversion into mechanical work is performed obeying a polytropic path function instead of the conventional adiabatic expansion without regeneration. Design characteristics concern the fact that combustion at constant volume is carried out undergoing large air excess so that the top combustion temperature is significantly lower than in conventional Otto cycles and consequently NOx emissions are neglected. Furthermore, during the polytropic expansion based path function, heat is absorbed by being submitted to a controlled heat flow rate, to achieve the desired polytropic expansion. The analysis of the regenerative Otto based on polytropic expansion is presented and results are compared with a regenerative Otto based on the adiabatic expansion and CF. The results show that a relevant advantage of the proposed regenerative Otto with polytropic expansion over the regenerative Otto cycle with adiabatic expansion involves performance enhancement within a wide range of combustion pressures, temperatures and regeneration capacities. Thus, thermal efficiency and specific work as function of the top combustion pressure ranges are of 71.95–58.43% and 143.5–173.6 kJ/kg respectively, when combustion pressures vary between 105 kPa and 200 kPa and CF is 60.8% (lower than the thermal efficiency). The successful results involving a compact engine structure, technically and economically viable, promises a new generation

Radio-Frequency-Based NH₃-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences.

Science.gov (United States)

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-07-12

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH₃ storage control, the influence of the storage degree on the catalyst performance, i.e., on NO x conversion and NH₃ slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH₃ storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

Functions and regulation of the Nox family in the filamentous fungus Podospora anserina: a new role in cellulose degradation.

Science.gov (United States)

Brun, Sylvain; Malagnac, Fabienne; Bidard, Frédérique; Lalucque, Hervé; Silar, Philippe

2009-10-01

NADPH oxidases are enzymes that produce reactive oxygen species. Studies in mammals, plants and fungi have shown that they play important roles in differentiation, defence, host/pathogen interaction and mutualistic symbiosis. In this paper, we have identified a Podospora anserina mutant strain impaired for processes controlled by PaNox1 and PaNox2, the two Nox isoforms characterized in this model ascomycete. We show that the gene mutated is PaNoxR, the homologue of the gene encoding the regulatory subunit p67(phox), conserved in mammals and fungi, and that PaNoxR regulates both PaNox1 and PaNox2. Genome sequence analysis of P. anserina reveals that this fungus posses a third Nox isoform, PaNox3, related to human Nox5/Duox and plant Rboh. We have generated a knock-out mutant of PaNox3 and report that PaNox3 plays a minor role in P. anserina, if any. We show that PaNox1 and PaNox2 play antagonist roles in cellulose degradation. Finally, we report for the first time that a saprobic fungus, P. anserina, develops special cell structures dedicated to breach and to exploit a solid cellulosic substrate, cellophane. Importantly, as for similar structures present in some plant pathogens, their proper differentiation requires PaNox1, PaNox2, PaNoxR and the tetraspanin PaPls1.

SCR96, a small cysteine-rich secretory protein of Phytophthora cactorum, can trigger cell death in the Solanaceae and is important for pathogenicity and oxidative stress tolerance.

Science.gov (United States)

Chen, Xiao-Ren; Li, Yan-Peng; Li, Qi-Yuan; Xing, Yu-Ping; Liu, Bei-Bei; Tong, Yun-Hui; Xu, Jing-You

2016-05-01

Peptides and small molecules produced by both the plant pathogen Phytophthora and host plants in the apoplastic space mediate the relationship between the interplaying organisms. Various Phytophthora apoplastic effectors, including small cysteine-rich (SCR) secretory proteins, have been identified, but their roles during interaction remain to be determined. Here, we identified an SCR effector encoded by scr96, one of three novel genes encoding SCR proteins in P. cactorum with similarity to the P. cactorum phytotoxic protein PcF. Together with the other two genes, scr96 was transcriptionally induced throughout the developmental and infection stages of the pathogen. These genes triggered plant cell death (PCD) in the Solanaceae, including Nicotiana benthamiana and tomato. The scr96 gene did not show single nucleotide polymorphisms in a collection of P. cactorum isolates from different countries and host plants, suggesting that its role is essential and non-redundant during infection. Homologues of SCR96 were identified only in oomycetes, but not in fungi and other organisms. A stable protoplast transformation protocol was adapted for P. cactorum using green fluorescent protein as a marker. The silencing of scr96 in P. cactorum caused gene-silenced transformants to lose their pathogenicity on host plants and these transformants were significantly more sensitive to oxidative stress. Transient expression of scr96 partially recovered the virulence of gene-silenced transformants on plants. Overall, our results indicate that the P. cactorum scr96 gene encodes an important virulence factor that not only causes PCD in host plants, but is also important for pathogenicity and oxidative stress tolerance. © 2015 BSPP AND JOHN WILEY & SONS LTD.

Regulation of Nox enzymes expression in vascular pathophysiology: Focusing on transcription factors and epigenetic mechanisms

Directory of Open Access Journals (Sweden)

Simona-Adriana Manea

2015-08-01

Full Text Available NADPH oxidases (Nox represent a family of hetero-oligomeric enzymes whose exclusive biological function is the generation of reactive oxygen species (ROS. Nox-derived ROS are essential modulators of signal transduction pathways that control key physiological activities such as cell growth, proliferation, migration, differentiation, and apoptosis, immune responses, and biochemical pathways. Enhanced formation of Nox-derived ROS, which is generally associated with the up-regulation of different Nox subtypes, has been established in various pathologies, namely cardiovascular diseases, diabetes, obesity, cancer, and neurodegeneration. The detrimental effects of Nox-derived ROS are related to alterations in cell signalling and/or direct irreversible oxidative damage of nucleic acids, proteins, carbohydrates, and lipids. Thus, understanding of transcriptional regulation mechanisms of Nox enzymes have been extensively investigated in an attempt to find ways to counteract the excessive formation of Nox-derived ROS in various pathological states. Despite the numerous existing data, the molecular pathways responsible for Nox up-regulation are not completely understood. This review article summarizes some of the recent advances and concepts related to the regulation of Nox expression in the vascular pathophysiology. It highlights the role of transcription factors and epigenetic mechanisms in this process. Identification of the signalling molecules involved in Nox up-regulation, which is associated with the onset and development of cardiovascular dysfunction may contribute to the development of novel strategies for the treatment of cardiovascular diseases.

Plasma and catalyst for the oxidation of NOx

DEFF Research Database (Denmark)

Jögi, I.; Erme, K.; Levoll, E.

2017-01-01

The removal of NOx from the exhaust gases requires the oxidation of most abundant NO to NO2 or N2O5. The oxidation can be done by non-thermal plasma but the efficiency is limited due to the back-reaction of NO2 to NO by O radicals. Present contribution investigates the role of catalysts in the im......The removal of NOx from the exhaust gases requires the oxidation of most abundant NO to NO2 or N2O5. The oxidation can be done by non-thermal plasma but the efficiency is limited due to the back-reaction of NO2 to NO by O radicals. Present contribution investigates the role of catalysts...... in the improvement of oxidation efficiency based on the stationary and time-dependent studies of the NOx oxidation at different reactor configurations and experimental conditions. The plasma produced active oxygen species (O, O3) were shown to play an important role in the reactions taking place on the catalyst...... surfaces while the exact mechanism and extent of the effect depended on the reactor configuration. The effect of catalyst at different experimental conditions was quantitatively described with the aid of analytical lumped kinetic models derived for the NOx oxidation when the catalyst was directly...

Analysis of the offshore installations regulations 2005 (SCR05r12) within Brazilian reality; Analise da regulacao das instalacoes offshore 2005 (SCR05r12) dentro da realidade brasileira

Energy Technology Data Exchange (ETDEWEB)

Nalvarte, Gladys; Storch, Rafael; Araujo, Pedro; Oliveira, Luiz Fernando [Det Norske Veritas (Brazil)

2008-07-01

The main motivation for the present study is the modifications presented in the guidance Offshore Installations (Safety Case) Regulations 2005 (SCR05 r12), released by HSE, in relation to the Offshore Installation Regulation 1992, SCR92. A critical analysis of the new regulation issued by HSE is developed and conclusions are obtained. A cost-benefit approach applied to the Quantitative Risk Analysis (QRA), using computational fluid dynamics (CFD) techniques, is suggested. Thereby, a method to identify the mitigation measures that most reduces the risks with the minimum cost is obtained. On the other hand, this new QRA approach combined with a cost benefit analysis is intended to have a total cost diminished. In this case, the cost of the new QRA study is dependant on the number of reevaluations needed to determine the mitigation measures to be applied. (author)

Organizers and activators: Cytosolic Nox proteins impacting on vascular function.

Science.gov (United States)

Schröder, Katrin; Weissmann, Norbert; Brandes, Ralf P

2017-08-01

NADPH oxidases of the Nox family are important enzymatic sources of reactive oxygen species (ROS) in the cardiovascular system. Of the 7 members of the Nox family, at least three depend for their activation on specific cytosolic proteins. These are p47phox and its homologue NoxO1 and p67phox and its homologue NoxA1. Also the Rho-GTPase Rac is important but as this protein has many additional functions, it will not be covered here. The Nox1 enzyme is preferentially activated by the combination of NoxO1 with NoxA1, whereas Nox2 gains highest activity with p47phox together with p67phox. As p47phox, different to NoxO1 contains an auto inhibitory region it has to be phosphorylated prior to complex formation. In the cardio-vascular system, all cytosolic Nox proteins are expressed but the evidence for their contribution to ROS production is not well established. Most data have been collected for p47phox, whereas NoxA1 has basically not yet been studied. In this article the specific aspects of cytosolic Nox proteins in the cardiovascular system with respect to Nox activation, their expression and their importance will be reviewed. Finally, it will be discussed whether cytosolic Nox proteins are suitable pharmacological targets to tamper with vascular ROS production. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Top-down NOX Emissions of European Cities Derived from Modelled and Spaceborne Tropospheric NO2 Columns

Science.gov (United States)

Verstraeten, W. W.; Boersma, K. F.; Douros, J.; Williams, J. E.; Eskes, H.; Delcloo, A. W.

2017-12-01

High nitrogen oxides (NOX = NO + NO2) concentrations near the surface impact humans and ecosystems badly and play a key role in tropospheric chemistry. NO2 is an important precursor of tropospheric ozone (O3) which in turn affects the production of the hydroxyl radical controlling the chemical lifetime of key atmospheric pollutants and reactive greenhouse gases. Combustion from industrial, traffic and household activities in large and densely populated urban areas result in high NOX emissions. Accurate mapping of these emissions is essential but hard to do since reported emissions factors may differ from real-time emissions in order of magnitude. Modelled NO2 levels and lifetimes also have large associated uncertainties and overestimation in the chemical lifetime which may mask missing NOX chemistry in current chemistry transport models (CTM's). The simultaneously estimation of both the NO2 lifetime and as well as the concentrations by applying the Exponentially Modified Gaussian (EMG) method on tropospheric NO2 columns lines densities should improve the surface NOX emission estimates. Here we evaluate if the EMG methodology applied on the tropospheric NO2 columns simulated by the LOTOS-EUROS (Long Term Ozone Simulation-European Ozone Simulation) CTM can reproduce the NOX emissions used as model input. First we process both the modelled tropospheric NO2 columns for the period April-September 2013 for 21 selected European urban areas under windy conditions (averaged vertical wind speeds between surface and 500 m from ECMWF > 2 m s-1) as well as the accompanying OMI (Ozone Monitoring Instrument) data providing us with real-time observation-based estimates of midday NO2 columns. Then we compare the top-down derived surface NOX emissions with the 2011 MACC-III emission inventory, used in the CTM as input to simulate the NO2 columns. For cities where NOX emissions can be assumed as originating from one large source good agreement is found between the top-down derived

Investigation of PCDD/F emissions from mobile source diesel engines: impact of copper zeolite SCR catalysts and exhaust aftertreatment configurations.

Science.gov (United States)

Liu, Z Gerald; Wall, John C; Barge, Patrick; Dettmann, Melissa E; Ottinger, Nathan A

2011-04-01

This study investigated the impact of copper zeolite selective catalytic reduction (SCR) catalysts and exhaust aftertreatment configurations on the emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from mobile source diesel engines. Emissions of PCDD/Fs, reported as the weighted sum of 17 congeners called the toxic equivalency quotient (TEQ), were measured using a modified EPA Method 0023A in the absence and presence of exhaust aftertreatment. Engine-out emissions were measured as a reference, while aftertreatment configurations included various combinations of diesel oxidation catalyst (DOC), diesel particulate filter (DPF), Cu-zeolite SCR, Fe-zeolite SCR, ammonia oxidation catalyst (AMOX), and aqueous urea dosing. In addition, different chlorine concentrations were evaluated. Results showed that all aftertreatment configurations reduced PCDD/F emissions in comparison to the engine-out reference, consistent with reduction mechanisms such as thermal decomposition or combined trapping and hydrogenolysis reported in the literature. Similarly low PCDD/F emissions from the DOC-DPF and the DOC-DPF-SCR configurations indicated that PCDD/F reduction primarily occurred in the DOC-DPF with no noticeable contribution from either the Cu- or Fe-zeolite SCR systems. Furthermore, experiments performed with high chlorine concentration provided no evidence that chlorine content has an impact on the catalytic synthesis of PCDD/Fs for the chlorine levels investigated in this study.

Predicting mercury retention in utility gas cleaning systems with SCR/ESP/FGD combinations or activated carbon injection

Energy Technology Data Exchange (ETDEWEB)

Krishnakumar, Balaji; Naik, Chitralkumar V.; Niksa, Stephen [Niksa Energy Associates LLC, Belmont, CA (United States); Fujiwara, Naoki [Idemitsu Kosan Co., Ltd, Chiba (Japan). Coal and Environment Research Lab.

2013-07-01

This paper presents validations of the Hg speciation predicted by NEA's MercuRator trademark package with an American field test database for 28 full-scale utility gas cleaning systems. It emphasizes SCR/ESP/FGD combinations and activated carbon injection because these two applications present the best long- term prospects for Hg control by coal-burning utilities. Validations of the extents of Hg{sup 0} oxidation across SCRs and of Hg retention in wet FGDs gave correlation coefficients greater than 0.9 for both units. A transport-based FGD analysis correctly assessed the potential for Hg{sup 0} re-emission in one limestone wet FGD. Among the ten stations in the SCR/ESP/FGD validations, the simulations correctly identified 3 of 4 of the relatively high Hg emissions rates; all four of the sites with moderate emissions rates; and both sites with the lowest emission rates. The validations for ACI applications demonstrated that Hg removals can be accurately estimated for the full domain of coal quality, LOI, and ACI rates for both untreated and brominated carbon sorbents. The predictions for ACI depict the test-to-test variations in most cases, and accurately describe the impact of ACI configuration and sorbent type. ACI into FFs is the most effective configuration, although ACI into ESPs often removes 90% or more Hg, provided that there is sufficient residence time and Cl in the flue gas. Brominated sorbents perform better than untreated carbons, unless SO{sub 3} condensation inhibits Hg adsorption.

Effects of dark chocolate on NOX-2-generated oxidative stress in patients with non-alcoholic steatohepatitis.

Science.gov (United States)

Loffredo, L; Del Ben, M; Perri, L; Carnevale, R; Nocella, C; Catasca, E; Baratta, F; Ceci, F; Polimeni, L; Gozzo, P; Violi, F; Angelico, F

2016-08-01

Activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is considered a pathogenetic mechanism determining fibrosis and disease progression in non-alcoholic steatohepatitis (NASH). Polyphenols exert antioxidant action and inhibit NADPH oxidase in humans. To analyse the effect of cocoa polyphenols on NADPH oxidase isoform 2 (NOX2) activation, oxidative stress and hepatocyte apoptosis in a population affected by NASH. In a cross-sectional study comparing 19 NASH and 19 controls, oxidative stress, as assessed by serum NOX2 activity and F2-isoprostanes, and hepatocyte apoptosis, as assessed by serum cytokeratin-18 (CK-18) levels, were measured. Furthermore, the 19 NASH patients were randomly allocated in a crossover design to 40 g/day of dark chocolate (>85% cocoa) or 40 g/day of milk chocolate (chocolate intake. Compared to controls, NASH patients had higher sNOX2-dp, serum isoprostanes and CK-18 levels. A significant difference for treatments was found in subjects with respect to sNOX2-dp, serum isoprostanes and serum CK-18. The pairwise comparisons showed that, compared to baseline, after 14 days of dark chocolate intake, a significant reduction in sNOX2-dp serum isoprostanes and CK-18 M30 was found. No change was observed after milk chocolate ingestion. A simple linear regression analysis showed that ∆ of sNOX2-dp was associated with ∆ of serum isoprostanes. Cocoa polyphenols exert an antioxidant activity via NOX2 down-regulation in NASH patients. © 2016 John Wiley & Sons Ltd.

NOx processing on Solar gas turbines; Turbines, traitement des nox sur les turbines a gaz solar

Energy Technology Data Exchange (ETDEWEB)

Chausse, X. [Spie Trindel, 95 - Cergy (France). Service TAG

1997-12-31

The Solar Company, in cooperation with Tuma Turbomach, has developed the SoLoNOx combustion system with a dry, lean, premixed compound, allowing for reduced NOx and CO emission levels (respectively 42 ppmv and 50 ppmv at 15 pc O{sub 2}). The combustor size is larger than a conventional combustor in order to maintain combustion efficiency and reduce carbon monoxide levels. Leaner combustion occurs at lower temperatures which produce less nitrogen oxides but require more volume to complete the combustion process. New developments should allow for a further reduction of NOx level at 25 ppmv

High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

Science.gov (United States)

Biess, J. J.; Inouye, L. Y.; Shank, J. H.

1974-01-01

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

Influence of flue gas desulfurization (FGD) installations on emission characteristics of PM2.5 from coal-fired power plants equipped with selective catalytic reduction (SCR).

Science.gov (United States)

Li, Zhen; Jiang, Jingkun; Ma, Zizhen; Fajardo, Oscar A; Deng, Jianguo; Duan, Lei

2017-11-01

Flue gas desulfurization (FGD) and selective catalytic reduction (SCR) technologies have been widely used to control the emissions of sulphur dioxide (SO 2 ) and nitrogen oxides (NO X ) from coal-fired power plants (CFPPs). Field measurements of emission characteristics of four conventional CFPPs indicated a significant increase in particulate ionic species, increasing PM 2.5 emission with FGD and SCR installations. The mean concentrations of PM 2.5 from all CFPPs tested were 3.79 ± 1.37 mg/m 3 and 5.02 ± 1.73 mg/m 3 at the FGD inlet and outlet, respectively, and the corresponding contributions of ionic species were 19.1 ± 7.7% and 38.2 ± 7.8%, respectively. The FGD was found to enhance the conversion of NH 3 slip from the SCR to NH 4 + in the PM 2.5 , together with the conversion of SO 2 to SO 4 2- , and increased the primary NH 4 + and SO 4 2- aerosol emissions by approximately 18.9 and 4.2 times, respectively. This adverse effect should be considered when updating the emission inventory of CFPPs and should draw the attention of policy-makers for future air pollution control. Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR 96.85 - NOX Budget opt-in permit contents.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget opt-in permit contents. 96... (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.85 NOX Budget opt-in permit contents. (a) Each NOX Budget opt-in permit...

40 CFR 97.85 - NOX Budget opt-in permit contents.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget opt-in permit contents. 97... (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.85 NOX Budget opt-in permit contents. (a) Each NOX Budget opt-in permit will contain all elements...

Low-temperature SCR of NO with NH{sub 3} over activated semi-coke composite-supported rare earth oxides

Energy Technology Data Exchange (ETDEWEB)

Wang, Jinping; Yan, Zheng; Liu, Lili; Zhang, Yingyi; Zhang, Zuotai; Wang, Xidong, E-mail: xidong@pku.edu.cn

2014-08-01

The catalysts with different rare earth oxides (La, Ce, Pr and Nd) loaded onto activated semi-coke (ASC) via hydrothermal method are prepared for the selective catalytic reduction (SCR) of NO with NH{sub 3} at low temperature (150–300 °C). It is evidenced that CeO{sub 2} loaded catalysts present the best performance, and the optimum loading amount of CeO{sub 2} is about 10 wt%. Composite catalysts by doping La, Pr and Nd into CeO{sub 2} are prepared to obtain further improved catalytic properties. The SCR mechanism is investigated through various characterizations, including XRD, Raman, XPS and FT-IR, the results of which indicate that the oxygen defect plays an important role in SCR process and the doped rare earth elements effectively serve as promoters to increase the concentration of oxygen vacancies. It is also found that the oxygen vacancies in high concentration are favored for the adsorption of O{sub 2} and further oxidation of NO, which facilitates a rapid progressing of the following reduction reactions. The SCR process of NO with NH{sub 3} at low temperature over the catalysts of ASC composite-supported rare earth oxides mainly follows the Langmuir–Hinshlwood mechanism.

Improved Automotive NO (x) Aftertreatment System: Metal Ammine Complexes as NH3 Source for SCR Using Fe-Containing Zeolite Catalysts

DEFF Research Database (Denmark)

Johannessen, Tue; Schmidt, Henning; Frey, Anne Mette

2009-01-01

Ammonia storage is a challenge in the selective catalytic reduction of NO (x) in vehicles. We propose a new system, based on metal ammines as the ammonia source. In combination with iron containing zeolites as the SCR catalyst it should be possible to obtain a low temperature system for NO (x...

Wintertime Overnight NOx Removal in a Southeastern United States Coal-fired Power Plant Plume: A Model for Understanding Winter NOx Processing and its Implications

Science.gov (United States)

Fibiger, Dorothy L.; McDuffie, Erin E.; Dubé, William P.; Aikin, Kenneth C.; Lopez-Hilfiker, Felipe D.; Lee, Ben H.; Green, Jaime R.; Fiddler, Marc N.; Holloway, John S.; Ebben, Carlena; Sparks, Tamara L.; Wooldridge, Paul; Weinheimer, Andrew J.; Montzka, Denise D.; Apel, Eric C.; Hornbrook, Rebecca S.; Hills, Alan J.; Blake, Nicola J.; DiGangi, Josh P.; Wolfe, Glenn M.; Bililign, Solomon; Cohen, Ronald C.; Thornton, Joel A.; Brown, Steven S.

2018-01-01

Nitric oxide (NO) is emitted in large quantities from coal-burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO3 and therefore unable to participate in next-day ozone (O3) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity campaign to test sensitivity of overnight NOx removal to the N2O5 loss rate constant, plume mixing rate, background O3, and background levels of volatile organic compounds using a 2-D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOx removal was the loss rate constant of N2O5. At the lowest observed N2O5 loss rate constant, no other combination of conditions converts more than 10% of the initial NOx to HNO3. The other factors did not influence NOx removal to the same degree.

Wintertime Overnight NOx Removal in a Southeastern United States Coal-Fired Power Plant Plume: A Model for Understanding Winter NOx Processing and Its Implications

Science.gov (United States)

Fibiger, Dorothy L.; McDuffie, Erin E.; Dube, William P.; Aikin, Kenneth C.; Lopez-Hilifiker, Felipe D.; Lee, Ben H.; Green, Jaime R.; Fiddler, Marc N.; Holloway, John S.; Ebben, Carlena;

Experience from performance testing of low NOx burners for refinery heaters; Tests de performance avec des bruleurs de raffinerie a basse emission de NOx

Energy Technology Data Exchange (ETDEWEB)

Boden, J.C. [Refining Technology, BP Oil International, Sunbury (United Kingdom)

2001-07-01

Developments in low NOx burner technology have resulted in major reductions in NOx emissions from refinery process heaters. However, the techniques used in low NOx burners to reduce NOx emissions can potentially affect other key aspects of burner performance, particularly flame stability and completeness of combustion. BP has evaluated many of the currently available low and ultra-low NOx burners, both natural and forced draught, in its purpose-built test furnace. This extensive test programme has shown that to be a reliable predictor of actual performance a test rig must recreate accurately the real furnace conditions, particularly with respect to furnace and hearth temperatures. The testing has demonstrated the NOx emissions to be expected in practice from different generic types of burner, conventional, low NOx and ultra-low NOx, and has highlighted the sets of conditions most likely to lead to combustion performance problems. (authors)

STAT5A-mediated NOX5-L expression promotes the proliferation and metastasis of breast cancer cells

Energy Technology Data Exchange (ETDEWEB)

Dho, So Hee [Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806 (Korea, Republic of); Radioisotope Research Division, Department of Research Reactor Utilization, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, Ji Young; Lee, Kwang-Pyo; Kwon, Eun-Soo [Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806 (Korea, Republic of); Lim, Jae Cheong [Radioisotope Research Division, Department of Research Reactor Utilization, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, Chang-Jin [Department of Pathology, Soonchunhyang Medical Science Research Institute, Chonan 330-090 (Korea, Republic of); Jeong, Dongjun, E-mail: juny1024@sch.ac.kr [Department of Pathology, Soonchunhyang Medical Science Research Institute, Chonan 330-090 (Korea, Republic of); Kwon, Ki-Sun, E-mail: kwonks@kribb.re.kr [Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806 (Korea, Republic of); Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon 305-333 (Korea, Republic of)

2017-02-01

NADPH oxidase (NOX) generates reactive oxygen species (ROS) and has been suggested to mediate cell proliferation in some cancers. Here, we show that an increase in the expression of NOX5 long form (NOX5-L) is critical for tumor progression in breast tumor tissues. Immunostaining of clinical samples indicated that NOX5 was overexpressed in 41.1% of breast ductal carcinoma samples. NOX5-L depletion consistently suppressed cell proliferation, invasion, and migration in vitro. Antibody-mediated neutralization of NOX5-L attenuated tumor progression in a mouse xenograft model. Promoter analysis revealed that NOX5-L expression is regulated by STAT5A in breast cancer cells. Based on our novel findings, we suggest that inhibition of NOX5-L may be a promising therapeutic strategy that exerts anti-cancer effects via the modulation of ROS-mediated cell signaling. - Highlights: • The ROS-generating protein, NOX5-L, determines cellular proliferation and metastasis in subset of breast tumor. • Tumor growth was attenuated by the treatment of anti-NOX5-L antibody in a xenograft model. • NOX5-L expression is transcriptionally regulated by STAT5A in breast cancer cells.

Reinforcement-learning-based output-feedback control of nonstrict nonlinear discrete-time systems with application to engine emission control.

Science.gov (United States)

Shih, Peter; Kaul, Brian C; Jagannathan, Sarangapani; Drallmeier, James A

2009-10-01

A novel reinforcement-learning-based output adaptive neural network (NN) controller, which is also referred to as the adaptive-critic NN controller, is developed to deliver the desired tracking performance for a class of nonlinear discrete-time systems expressed in nonstrict feedback form in the presence of bounded and unknown disturbances. The adaptive-critic NN controller consists of an observer, a critic, and two action NNs. The observer estimates the states and output, and the two action NNs provide virtual and actual control inputs to the nonlinear discrete-time system. The critic approximates a certain strategic utility function, and the action NNs minimize the strategic utility function and control inputs. All NN weights adapt online toward minimization of a performance index, utilizing the gradient-descent-based rule, in contrast with iteration-based adaptive-critic schemes. Lyapunov functions are used to show the stability of the closed-loop tracking error, weights, and observer estimates. Separation and certainty equivalence principles, persistency of excitation condition, and linearity in the unknown parameter assumption are not needed. Experimental results on a spark ignition (SI) engine operating lean at an equivalence ratio of 0.75 show a significant (25%) reduction in cyclic dispersion in heat release with control, while the average fuel input changes by less than 1% compared with the uncontrolled case. Consequently, oxides of nitrogen (NO(x)) drop by 30%, and unburned hydrocarbons drop by 16% with control. Overall, NO(x)'s are reduced by over 80% compared with stoichiometric levels.

Numerical simulation of urea based selective non-catalytic reduction deNOx process for industrial applications

International Nuclear Information System (INIS)

Baleta, Jakov; Mikulčić, Hrvoje; Vujanović, Milan; Petranović, Zvonimir; Duić, Neven

2016-01-01

Highlights: • SNCR is a simple method for the NOx reduction from large industrial facilities. • Capabilities of the developed mathematical framework for SNCR simulation were shown. • Model was used on the geometry of experimental reactor and municipal incinerator. • Results indicate suitability of the developed model for real industrial cases. - Abstract: Industrial processes emit large amounts of diverse pollutants into the atmosphere, among which NOx takes a significant portion. Selective non-catalytic reduction (SNCR) is a relatively simple method for the NOx reduction in large industrial facilities such as power plants, cement plants and waste incinerator plants. It consists of injecting the urea-water solution in the hot flue gas stream and its reaction with the NOx. During this process flue gas enthalpy is used for the urea-water droplet heating and for the evaporation of water content. After water evaporates, thermolysis of urea occurs, during which ammonia, a known NO_x reductant, and isocyanic acid are generated. In order to cope with the ever stringent environmental norms, equipment manufacturers need to develop energy efficient products that are at the same time benign to environment. This is becoming increasingly complicated and costly, and one way to reduce production costs together with the maintaining the same competitiveness level is to employ computational fluid dynamics (CFD) as a tool, in a process today commonly known under the term “virtual prototyping”. The aim of this paper is to show capabilities of the developed mathematical framework implemented in the commercial CFD code AVL FIRE®, to simulate physical processes of all relevant phenomena occurring during the SNCR process. First, mathematical models for description of SNCR process are presented and afterwards, models are used on the 3D geometry of an industrial reactor and a real industrial case to predict SNCR efficiency, temperature and velocity field. Influence of the main

Design and preliminary results for a fast bipolar resonant discharge pulser using SCR switches for driving the injection bump magnets at the ALS

International Nuclear Information System (INIS)

Stover, G.; Reginato, L.

1993-05-01

A fast (4.0 us half period) resonant discharge pulser using SCRs has been designed and constructed to drive the injection bump magnet system at the Advanced Light Source (ALS). The pulser employs a series-parallel arrangement of Silicon Controlled Rectifiers (SCRS) that creates a bipolar high voltage (±10 KV), high peak current (6600 amps.) and a high di/dt (6000 amp/us) switch network that discharges a capacitor bank into the magnet load. Fast recovery diodes in series with the SCRs significantly reduces the SCR turn-off time during the negative current cycle of the magnet. The SCR switch provides a very reliable and stable alternative to the gas filled Thyratron. A very low impedance transmission system allows the pulser system to reside completely outside the storage ring shielding wall

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

Directory of Open Access Journals (Sweden)

Ralf Moos

2010-07-01

Full Text Available Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

Science.gov (United States)

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters. PMID:22163575

Nighttime NOx Chemistry in Coal-Fired Power Plant Plumes

Science.gov (United States)

Fibiger, D. L.; McDuffie, E. E.; Dube, W. P.; Veres, P. R.; Lopez-Hilfiker, F.; Lee, B. H.; Green, J. R.; Fiddler, M. N.; Ebben, C. J.; Sparks, T.; Weinheimer, A. J.; Montzka, D.; Campos, T. L.; Cohen, R. C.; Bililign, S.; Holloway, J. S.; Thornton, J. A.; Brown, S. S.

2015-12-01

Nitrogen oxides (NOx = NO + NO2) play a key role in atmospheric chemistry. During the day, they catalyze ozone (O3) production, while at night they can react to form nitric acid (HNO3) and nitryl chloride (ClNO2) and remove O3 from the atmosphere. These processes are well studied in the summer, but winter measurements are more limited. Coal-fired power plants are a major source of NOx to the atmosphere, making up approximately 30% of emissions in the US (epa.gov). NOx emissions can vary seasonally, as well as plant-to-plant, with important impacts on the details of the plume chemistry. In particular, due to inefficient plume dispersion, nighttime NOx emissions from power plants are held in concentrated plumes, where rates of mixing with ambient O3 have a strong influence on plume evolution. We will show results from the aircraft-based WINTER campaign over the northeastern United States, where several nighttime intercepts of power plant plumes were made. Several of these intercepts show complete O3 titration, which can have a large influence on NOx lifetime, and thus O3 production, in the plume. When power plant NO emissions exceed background O3 levels, O3 is completely consumed converting NO to NO2. In the presence of O3, NO2 will be oxidized to NO3, which will then react with NO2 to form N2O5, which can then form HNO3 and/or ClNO2 and, ultimately, remove NOx from the atmosphere or provide next-day oxidant sources. If there is no O3 present, however, no further chemistry can occur and NO and NO2 will be transported until mixing with sufficient O3 for higher oxidation products. Modeling results of plume development and mixing, which can tell us more about this transport, will also be presented.

NOx Control Options and Integration for US Coal Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Mike Bockelie; Kevin Davis; Temi Linjewile; Connie Senior; Eric Eddings; Kevin Whitty; Larry Baxter; Calvin Bartholomew; William Hecker; Stan Harding

2003-09-30

This is the thirteenth Quarterly Technical Report for DOE Cooperative Agreement No: DEFC26-00NT40753. The goal of the project is to develop cost effective analysis tools and techniques for demonstrating and evaluating low NO{sub x} control strategies and their possible impact on boiler performance for boilers firing US coals. The Electric Power Research Institute (EPRI) is providing co-funding for this program. This program contains multiple tasks and good progress is being made on all fronts. The corrosion probe task is proceeding: Two plant visits were made to prepare for field testing and shakedown tests for the probes were conducted at the University of Utah''s L1500 furnace. Corrosion probes will be installed at the Gavin Plant site in the next quarter. Laboratory studies of SCR catalyst continued this quarter. FTIR studies of catalyst sulfation and of adsorption of NH3 and NO were continued at BYU. NO activities have been measured for a number of samples of BYU catalyst and insights have been gained from the results. Plans are being detailed to test monolith and plate catalysts exposed in the field. In this quarter, the catalysts in the slipstream reactor at AEP's Rockport plant were exposed to the dusty flue gas for 1695 hours. Thus the cumulative catalyst exposure to flue gas rose from 980 hours last quarter to 2677 hours in this quarter. Loss of catalyst activity was noted between April (when the catalysts were fresh) and August. Further analysis of activity data will be needed.

Advanced combustor design concept to control NOx and air toxics

Energy Technology Data Exchange (ETDEWEB)

Eddings, E.G.; Pershing, D.W.; Molina, A.; Sarofim, A.F.; Spinti, J.P.; Veranth, J.

1999-03-29

Direct coal combustion needs to be a primary energy source for the electric utility industry and for heavy manufacturing during the next several decades because of the availability and economic advantage of coal relative to other fuels and because of the time required to produce major market penetration in the energy field. However, the major obstacle to coal utilization is a set of ever-tightening environmental regulations at both the federal and local level. It is, therefore, critical that fundamental research be conducted to support the development of low-emission, high-efficiency pulverized coal power systems. The objective of this program was to develop fundamental understanding regarding the impact of fuel and combustion changes on NOx formation, carbon burnout and air toxic emissions from pulverized coal (pc) combustion. During pc combustion, nitrogen in the coal can be oxidized to form nitrogen oxides (NO{sub x}). The 1990 Clean Air Act Amendments established much stricter NO{sub x} emissions limits for new and existing coal-fired plants, so there has been renewed interest in the processes by which NO{sub x} forms in pc flames. One of the least understood aspects of NO{sub x} formation from pc combustion is the process by which char-N (nitrogen remaining in the char after devolatilization) forms either NO{sub x} or N{sub 2}, and the development of a fundamental understanding of this process was a major focus of this research. The overall objective of this program was to improve the ability of combustion system designers and boiler manufacturers to build high efficiency, low emission pulverized coal systems by improving the design tools available to the industry. The specific program goals were to: Use laboratory experiments and modeling to develop fundamental understanding for a new submodel for char nitrogen oxidation (a critical piece usually neglected in most NOx models.); Use existing bench scale facilities to investigate alternative schemes to

Successful design and application of SNCR parallel to combustion modification

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dongxian; Tang, Leping; Shao, Xiaozhen; Meng, Derun; Li, Hongjian [Tongfang Environment CO., LTD., Beijing (China); Zhou, Wei; Xu, Guang [GE Energy, Anaheim, CA (United States)

2013-07-01

Various De-NOx methods have been recently adopted in China to control NOx emissions including Selective Non-Catalytic Reaction (SNCR) technology. Usually, the design of SNCR system is carried out after the combustion modification technologies, such as low NOx burner (LNB) and over fire air (OFA), have already been installed and in operation. This article discusses how to design the SNCR system parallel to the combustion modification. The SNCR process design consists of three steps: (1) boiler baseline test, (2) computational fluid dynamics simulation (CFD) facilitated design and (3) SNCR system performance predictions and optimizations. The first step is to conduct boiler baseline test to characterize the boiler operating conditions at a load range. The test data can also be used to calibrate the CFD model. The second step is to develop a three-dimensional boiler coal combustion CFD model to simulate the operation of the boilers at both baseline and post combustion modification conditions. The simulation reveals velocity, temperature and combustible distributions in the furnace. The last step is to determine the position and numbers of the injectors for SNCR reagent. The final field tests upon the project completion have shown that the average SNCR De-NOx efficiency has reached 35.1% with the maximum removal efficiency of 45% on full load. The project also couples the SNCR and SCR (Selective Catalytic Reduction) technologies. The combined removal efficiency of combustion modifications, SNCR and SCR is higher than 82%. This paper shows a successful example for retrofitting aged power-generating units with limited space.

40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To...

Long term deactivation test of high dust SCR catalysts by straw co-firing

Energy Technology Data Exchange (ETDEWEB)

Weigang Lin; Degn Jensen, A.; Bjerkvig, J.

2009-12-15

The consequences of carbon dioxide induced global warming cause major concern worldwide. The consumption of energy produced with fossil fuels is the major factor that contributes to the global warming. Biomass is a renewable energy resource and has a nature of CO{sub 2} neutrality. Co-combustion of biomass in existing coal fired power plants can maintain high efficiency and reduce the emission of CO{sub 2} at same time. However, one of the problems faced by co-firing is deactivation of the SCR catalysts. Understanding of the mechanisms of deactivation of the catalyst elements at co-firing conditions is crucial for long term runs of the power plants. Twenty six SCR catalyst elements were exposed at two units (SSV3 and SSV4) in the Studstrup Power Plant for a long period. Both units co-fire coal and straw with a typical fraction of 8-10% straw on an energy basis during co-firing. SSV4 unit operated in co-firing mode most of the time; SSV3 unit co-fired straw half of the operating time. The main objective of this PSO-project is to gain knowledge of a long term influence on catalyst activity when co-firing straw in coal-fired power plants, thus, to improve the basis for operating the SCR-plants for NO{sub x}-reduction. The exposure time of the applied catalyst elements (HTAS and BASF) varied from approximately 5000 to 19000 hours in the power plant by exchanging the element two times. The activity of all elements was measured before and after exposure in a bench scale test rig at the Department of Chemical and Biochemical Engineering, Technical University of Denmark. The results show that the activity, estimated by exclusion of channel clogging of the elements, decreases gradually with the total exposure time. It appears that the exposure time under co-firing condition has little effect on the deactivation of the catalyst elements and no sharp decrease of the activity was observed. The average deactivation rate of the catalyst elements is 1.6 %/1000 hours. SEM

Exhaust Recirculation Control for Reduction of NOx from Large Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Nielsen, Kræn Vodder

Increased awareness of the detrimental effects on climate, ecosystems and human health have led to numerous restrictions of the emissions from internal combustion engines. Recently the International Maritime Organization has introduced the Tier III standard, which includes a significantly stricter...... the automotive industry, but have only recently been introduced commercially to large two-stroke diesel engines. Recirculation of exhaust gas to the cylinders lowers the oxygen availability and increases the heat capacity during combustion, which in turn leads to less formation of NOx. Experience shows...... of the Tier III standard, while still maintaining maneuverability performance without smoke formation. The design methods acknowledge that engine specific parameter tuning is a scarce resource in the industry and controller complexity is kept to a minimum. An existing dynamic model of the engine and EGR...

Deactivation of SCR catalysts in biomass fired power plants

DEFF Research Database (Denmark)

Olsen, Brian Kjærgaard

composition and operating conditions, is not available. The main objective of the work presented in this thesis has been to conduct an in depth investigation of the deactivation mechanism of vanadia based SCR catalysts, when subjected to potassium rich aerosols. It has furthermore been a goal to suggest...... for up to 600 hours. The activity of fresh and exposed catalysts was measured in the temperature range 250-400 °C in a laboratory-scale reactor. All samples exposed for more than 240 hours proved to have deactivated significantly, however, catalysts exposed at 150 °C showed higher remaining activity......-scale setup at 350 °C for up to 1100 hours, and their activities were followed by in situ measurements. A 3%V2O5-7%WO3/TiO2 reference catalyst deactivated with a rate of 0.91 %/day during 960 hours of exposure, and a subsequent SEM-EDS analysis showed complete potassium penetration of the catalyst wall...

Constitutive NADPH-dependent electron transferase activity of the Nox4 dehydrogenase domain.

Science.gov (United States)

Nisimoto, Yukio; Jackson, Heather M; Ogawa, Hisamitsu; Kawahara, Tsukasa; Lambeth, J David

2010-03-23

NADPH oxidase 4 (Nox4) is constitutively active, while Nox2 requires the cytosolic regulatory subunits p47(phox) and p67(phox) and activated Rac with activation by phorbol 12-myristate 13-acetate (PMA). This study was undertaken to identify the domain on Nox4 that confers constitutive activity. Lysates from Nox4-expressing cells exhibited constitutive NADPH- but not NADH-dependent hydrogen peroxide production with a K(m) for NADPH of 55 +/- 10 microM. The concentration of Nox4 in cell lysates was estimated using Western blotting and allowed calculation of a turnover of approximately 200 mol of H(2)O(2) min(-1) (mol of Nox4)(-1). A chimeric protein (Nox2/4) consisting of the Nox2 transmembrane (TM) domain and the Nox4 dehydrogenase (DH) domain showed H(2)O(2) production in the absence of cytosolic regulatory subunits. In contrast, chimera Nox4/2, consisting of the Nox4 TM and Nox2 DH domains, exhibited PMA-dependent activation that required coexpression of regulatory subunits. Nox DH domains from several Nox isoforms were purified and evaluated for their electron transferase activities. Nox1 DH, Nox2 DH, and Nox5 DH domains exhibited barely detectable activities toward artificial electron acceptors, while the Nox4 DH domain exhibited significant rates of reduction of cytochrome c (160 min(-1), largely superoxide dismutase-independent), ferricyanide (470 min(-1)), and other electron acceptors (artificial dyes and cytochrome b(5)). Rates were similar to those observed for H(2)O(2) production by the Nox4 holoenzyme in cell lysates. The activity required added FAD and was seen with NADPH but not NADH. These results indicate that the Nox4 DH domain exists in an intrinsically activated state and that electron transfer from NADPH to FAD is likely to be rate-limiting in the NADPH-dependent reduction of oxygen by holo-Nox4.

40 CFR 96.24 - Effective date of initial NOX Budget permit.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Effective date of initial NOX Budget... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.24 Effective date of initial NOX Budget permit. The initial NOX Budget permit...

40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...

40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.

Science.gov (United States)

2010-07-01

... as follows: (A) If the unit is coal-fired during the year, the unit's control period heat input for... control period heat input, and a unit's status as coal-fired or oil-fired, for a calendar year under... baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...

40 CFR 97.142 - CAIR NOX allowance allocations.

Science.gov (United States)

2010-07-01

... heat input for each year calculated as follows: (A) If the unit is coal-fired during the year, the unit... the first such 5 years. (2)(i) A unit's control period heat input, and a unit's status as coal-fired... Allocations § 97.142 CAIR NOX allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with...

40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.

Science.gov (United States)

2010-07-01

... calculated as follows: (A) If the unit is coal-fired during the year, the unit's control period heat input... control period heat input, and a unit's status as coal-fired or oil-fired, for a calendar year under... allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...

Maritime NOx Emissions Over Chinese Seas Derived From Satellite Observations

Science.gov (United States)

Ding, J.; van der A, R. J.; Mijling, B.; Jalkanen, J.-P.; Johansson, L.; Levelt, P. F.

2018-02-01

By applying an inversion algorithm to NOx satellite observations from Ozone Monitoring Instrument, monthly NOx emissions for a 10 year period (2007 to 2016) over Chinese seas are presented for the first time. No effective regulations on NOx emissions have been implemented for ships in China, which is reflected in the trend analysis of maritime emissions. The maritime emissions display a continuous increase rate of about 20% per year until 2012 and slow down to 3% after that. The seasonal cycle of shipping emissions has regional variations, but all regions show lower emissions during winter. Simulations by an atmospheric chemistry transport model show a notable influence of maritime emissions on air pollution over coastal areas, especially in summer. The satellite-derived spatial distribution and the magnitude of maritime emissions over Chinese seas are in good agreement with bottom-up studies based on the Automatic Identification System of ships.

SEMS operating as a proven system for screening real-world NOx and NH3 emissions

NARCIS (Netherlands)

Vermeulen, R.J.; Goethem, S. van; Baarbe, H.L.; Zuidgeest, L.W.M.; Spreen, J.S.; Vonk, W.A.

2014-01-01

NOx emissions of heavy-duty and light-duty diesel vehicles depend strongly on the driving conditions. The introduction of combined emission reduction technologies in Euro VI vehicles have demonstrated that NOx emissions become less predictable when the data is based on relatively short test cycles.

40 CFR 60.4340 - How do I demonstrate continuous compliance for NOX if I do not use water or steam injection?

Science.gov (United States)

2010-07-01

... compliance for NOX if I do not use water or steam injection? 60.4340 Section 60.4340 Protection of....4340 How do I demonstrate continuous compliance for NOX if I do not use water or steam injection? (a) If you are not using water or steam injection to control NOX emissions, you must perform annual...

SORBENT/UREA SLURRY INJECTION FOR SIMULTANEOUS SO2/NOX REMOVAL

Science.gov (United States)

The combination of sorbent injection and selective noncatalytic reduction (SNCR) technologies has been investigated for simulataneous SO2/NOx removal. A slurry composed of a urea-based solution and various Ca-based sorbents was injected at a range of tempera...

Evaluation of NOX emissions from TVA coal-fired power plants

International Nuclear Information System (INIS)

Jones, J.W.; Stamey-Hall, S.

1991-01-01

The paper gives results of a preliminary evaluation of nitrogen oxide (NOx) emissions from 11 Tennessee Valley Authority (TVA) coal-fired power plants. Current EPA AP-42 emission factors for NOx from coal-fired utility boilers do not account for variations either in these emissions as a function of generating unit load, or in designs of boilers of the same general type, particularly wall-fired boilers. The TVA has compiled short-term NOx emissions data from 30 units at 11 TVA coal-fired plants. These units include cyclone, cell burner, single wall, opposed wall, single tangential, and twin tangential boiler firing designs. Tests were conducted on 29 of the 30 units at high load; 18 were also tested at reduced load. NOx emissions rates were calculated for each test and compared to the calculated rate for each boiler type using AP-42. Preliminary analysis indicates that: (1) TVA cyclone-fired units emit more NOx than estimated using AP-42; (2) TVA cell burner units emit considerably more NOx than estimated; (3) most TVA single-wall-fired units emit slightly more NOx than estimated; (4) most TVA single-furnace tangentially fired units emit less NOx than estimated at high load, but the same as (or more than) estimated at reduced load; and (5) most TVA twin-furnace tangentially fired units, at high load, emit slightly more NOx than estimated using AP-42

NADPH Oxidase, NOX1, Mediates Vascular Injury in Ischemic Retinopathy

Science.gov (United States)

Deliyanti, Devy; Rana, Indrajeetsinh; Miller, Antonia G.; Agrotis, Alex; Armani, Roksana; Szyndralewiez, Cédric; Wingler, Kirstin; Touyz, Rhian M.; Cooper, Mark E.; Jandeleit-Dahm, Karin A.; Schmidt, Harald H.H.W.

2014-01-01

Abstract Aims: Ischemic retinal diseases such as retinopathy of prematurity are major causes of blindness due to damage to the retinal microvasculature. Despite this clinical situation, retinopathy of prematurity is mechanistically poorly understood. Therefore, effective preventative therapies are not available. However, hypoxic-induced increases in reactive oxygen species (ROS) have been suggested to be involved with NADPH oxidases (NOX), the only known dedicated enzymatic source of ROS. Our major aim was to determine the contribution of NOX isoforms (1, 2, and 4) to a rodent model of retinopathy of prematurity. Results: Using a genetic approach, we determined that only mice with a deletion of NOX1, but not NOX2 or NOX4, were protected from retinal neovascularization and vaso-obliteration, adhesion of leukocytes, microglial accumulation, and the increased generation of proangiogenic and proinflammatory factors and ROS. We complemented these studies by showing that the specific NOX inhibitor, GKT137831, reduced vasculopathy and ROS levels in retina. The source of NOX isoforms was evaluated in retinal vascular cells and neuro-glial elements. Microglia, the immune cells of the retina, expressed NOX1, 2, and 4 and responded to hypoxia with increased ROS formation, which was reduced by GKT137831. Innovation: Our studies are the first to identify the NOX1 isoform as having an important role in the pathogenesis of retinopathy of prematurity. Conclusions: Our findings suggest that strategies targeting NOX1 have the potential to be effective treatments for a range of ischemic retinopathies. Antioxid. Redox Signal. 20, 2726–2740. PMID:24053718

FTIR in situ mechanistic study of the NH3-NO/NO2 "Fast SCR" reaction over a commercial Fe-ZSM-5 catalyst

Czech Academy of Sciences Publication Activity Database

Ruggeri, M. P.; Grossale, A.; Nova, I.; Tronconi, E.; Jirglová, Hana; Sobalík, Zdeněk

2012-01-01

Roč. 184, č. 1 (2012), s. 107-114 ISSN 0920-5861 R&D Projects: GA AV ČR KAN100400702; GA ČR GA203/09/1627 Institutional research plan: CEZ:AV0Z40400503 Keywords : urea /NH3 SCR * fast SCR * NO2 adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

SCR activity of conformed CuOx/ZrO2-SO4 catalysts

DEFF Research Database (Denmark)

Rasmussen, Søren Birk; Yates, Malcolm; Due-Hansen, Johannes

2010-01-01

CuOX/ZrO2-SO4 catalysts have been synthesised as conformed materials with the use of sepiolite as agglomerant and the performance in the NH3-SCR reaction with relation to biomass fired boiler units have been studied. The optimal Cu-loading of the catalysts is 3 wt.% CuO, both in terms of activity...

40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.

Science.gov (United States)

2010-07-01

... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...

Characterization of Regional Marginal Abatement Cost Curves for NOx that Incorporate Control Measures, Renewable Energy, Energy Efficiency and Fuel Switching

Science.gov (United States)

Anthropogenic nitrogen oxides (NOx) are emitted when fossil fuels are combusted. In the atmosphere, NOx reacts with volatile organic compounds (VOCs) to produce tropospheric ozone, a component of photochemical smog. In most parts of the country, strategies for reducing ozone gene...

Development of a microscale NOx- biosensor for the study of nitrogen cycling in marine sediment

DEFF Research Database (Denmark)

Marzocchi, Ugo

application of this microscale biosensor is constrained mainly because of a short lifetime caused by the fragility of some of its components. Moreover a detailed study characterizing the ESC efficiency under different condition is still missing. The aims of this thesis are: (i) to contribute......-) microscale biosensor matches these requirements. In fact, it can be constructed with a tip diameter ranging between 25 and 100 µm. Its functioning is based on the reduction of NOx- to N2O by denitrifying bacteria and the subsequent detection of N2O by means of an amperometric microsensor. The sensitivity...... of the biosensor can be amplified by the electrophoretic sensitivity control system (ESC) which positively polarizes the inner side of the sensor against an external reference inserted into the analyzed medium, inducing the migration of NOx- anions into the bacterial chamber. However, nowadays the widespread...

A review of NOx formation mechanisms in recovery furnaces

International Nuclear Information System (INIS)

Nichols, K.M.; Thompson, L.M.; Empie, H.J.

1993-01-01

Review of NOx formation studies shows that NO forms in recovery furnaces primarily by two independent mechanisms, thermal and fuel. Thermal NO formation is extremely temperature-sensitive. However, theoretical predictions indicate that recovery furnace temperatures are not high enough to form significant thermal NO. Fuel NO formation is less temperature-sensitive, and is related to fuel nitrogen content. Black liquors are shown to contain 0.05 to 0.24 weight percent fuel nitrogen. Conversion of just 20% of this would yield approximately 25-120 ppm NOx (at 8% 0 2 ) in the flue gas, enough to represent the majority of the total NOx. Data from operating recovery furnaces show NOx emissions ranging from near zero to over 100 ppm at 8% 0 2 . An apparent increase in recovery furnace NOx emissions was observed with increasing solids. This increase is much less than predicted by thermal NO formation theory, indicating that other NO formation/destruction mechanisms, such as fuel NO formation, are important. No data are available to show the relative importance of thermal and fuel NO to total NOx during black liquor combustion

40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.

Science.gov (United States)

2010-07-01

... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...

Characterization of LSM/CGO Symmetric Cells Modified by NOx Adsorbents for Electrochemical NOx Removal with Impedance Spectroscopy

DEFF Research Database (Denmark)

Shao, Jing; Kammer Hansen, Kent

2013-01-01

in the resistance of the low-frequency processes, which were ascribed to adsorption, diffusion, and transfer of O2 species and NOx species at or near the triple phase boundary (TPB) region and the formation of the reaction intermediate NO2. The BaO impregnation improved the adsorption of NOx on the LSM....../CGO electrode by selectively trapping NO2 in the form of nitrate over the BaO sites and provided availability for a direct reduction of the stored nitrate. The BaO-Pt-Al2O3 layer enhanced the NOx adsorption and promoted the formation of NO2 due to the NO oxidation ability of the Pt catalyst, but hindered...... the gas diffusion to the reaction sites....

Nitrogen Isotope Composition of Thermally Produced NOx from Various Fossil-Fuel Combustion Sources.

Science.gov (United States)

Walters, Wendell W; Tharp, Bruce D; Fang, Huan; Kozak, Brian J; Michalski, Greg

2015-10-06

The nitrogen stable isotope composition of NOx (δ(15)N-NOx) may be a useful indicator for NOx source partitioning, which would help constrain NOx source contributions in nitrogen deposition studies. However, there is large uncertainty in the δ(15)N-NOx values for anthropogenic sources other than on-road vehicles and coal-fired energy generating units. To this end, this study presents a broad analysis of δ(15)N-NOx from several fossil-fuel combustion sources that includes: airplanes, gasoline-powered vehicles not equipped with a three-way catalytic converter, lawn equipment, utility vehicles, urban buses, semitrucks, residential gas furnaces, and natural-gas-fired power plants. A relatively large range of δ(15)N-NOx values was measured from -28.1‰ to 8.5‰ for individual exhaust/flue samples that generally tended to be negative due to the kinetic isotope effect associated with thermal NOx production. A negative correlation between NOx concentrations and δ(15)N-NOx for fossil-fuel combustion sources equipped with selective catalytic reducers was observed, suggesting that the catalytic reduction of NOx increases δ(15)N-NOx values relative to the NOx produced through fossil-fuel combustion processes. Combining the δ(15)N-NOx measured in this study with previous published values, a δ(15)N-NOx regional and seasonal isoscape was constructed for the contiguous U.S., which demonstrates seasonal and regional importance of various NOx sources.

Developing the multiple stress-strain creep recovery (MS-SCR) test

Science.gov (United States)

Elnasri, Mahmoud; Airey, Gordon; Thom, Nick

2018-04-01

While most published work from Europe has been concerned with evaluating binders' resistance to rutting based on their stiffness (deformation resistance), work originating in the US has mainly been concerned with ranking binders based on their recoverability in a multiple stress form. This paper details the design of a new modified multiple stress-strain creep recovery (MS-SCR) test. The test is designed to evaluate binders' rutting resistance based on two rutting resistance mechanisms: stiffness and recoverability. A preliminary investigation is presented in this paper followed by details of the design of the new modified test. A 40/60 penetration grade bitumen and bitumen-filler mastics prepared with three filler concentrations (35%, 50%, and 65% filler content by mass of mastic) were tested. In addition, two polymer modified bitumens (PMBs) using the same base bitumen type were examined for validation. Two parameters are introduced to characterise the short and long recovery in the new test. In terms of stiffness, the test allows the behaviour of binders at different stress levels and loading cycles to be studied and produces a new parameter that can quantify the degree of modification. Finally, a relationship between nonlinearity and normal force in the test was investigated.

40 CFR 1065.670 - NOX intake-air humidity and temperature corrections.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false NOX intake-air humidity and... NOX intake-air humidity and temperature corrections. See the standard-setting part to determine if you may correct NOX emissions for the effects of intake-air humidity or temperature. Use the NOX intake...

SSZ-13-supported manganese oxide catalysts for low temperature ...

Indian Academy of Sciences (India)

YONGZHOU YE

Their performances for the selective catalytic reduction (SCR) of NOx with NH3 were evaluated. ... catalysts have received considerable attention.2,3 More- over, catalysts ..... zeolite channels or causing agglomeration on the cat- alyst surface ...

40 CFR 96.83 - Applying for NOX Budget opt-in permit.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applying for NOX Budget opt-in permit... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.83 Applying for NOX Budget opt-in permit. (a) Applying for...

Effect of Ca-Fe oxides additives on NOx reduction in iron ore sintering

Institute of Scientific and Technical Information of China (English)

Zhi-yuan Yu; Xiao-hui Fan; Min Gan; Xu-ling Chen

2017-01-01

As the emission control regulations get stricter, the NOx reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain. The NOx emissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus, it is essential to reduce NOx emissions from the sintering machine, for the achievement of clean production of sinter.Ca-Fe oxides, serving as the main binding phase in the sinter, are therefore used as additives into the sintering mixture to reduce NOx emissions.The results show that the NOx re-duction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ig-nition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile, the exist-ence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point com-pounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8% since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines, inhibiting the mineralization reaction of sintering mixture.Additionally, the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of -0.5 mm and 0.5-3.0 mm in size.

Biodiesel unsaturation degree effects on diesel engine NOx emissions and cotton wick flame temperature

Directory of Open Access Journals (Sweden)

Abdullah Mohd Fareez Edzuan

2017-01-01

Full Text Available As compared with conventional diesel fuel, biodiesel has better lubricity and lower particulate matter (PM emissions however nitrogen oxides (NOx emissions generally increase in biodiesel-fuelled diesel engine. Strict regulation on NOx emissions is being implemented in current Euro 6 standard and it is expected to be tighter in next standard, thus increase of NOx cannot be accepted. In this study, biodiesel unsaturation degree effects on NOx emissions are investigated. Canola, palm and coconut oils are selected as the feedstock based on their unsaturation degree. Biodiesel blends of B20 were used to fuel a single cylinder diesel engine and exhaust emissions were sampled directly at exhaust tailpipe with a flue gas analyser. Biodiesel flame temperature was measured from a cotton wick burned in simple atmospheric conditions using a thermocouple. Fourier transform infrared (FTIR spectrometer was also used to identify the functional groups presence in the biodiesel blends. Oxygen content in biodiesel may promote complete combustion as the NOx emissions and flame temperatures were increased while the carbon monoxide (CO emissions were decreased for all biodiesel blends. It is interesting to note that the NOx emissions and flame temperatures were directly proportional with biodiesel unsaturation degree. It might be suggested that apart from excess oxygen and free radical formation, higher NOx emissions can also be caused by the elevated flame temperatures due to the presence of double bonds in unsaturated biodiesel.

Selection of best impregnated palm shell activated carbon (PSAC) for simultaneous removal of SO2 and NOx

International Nuclear Information System (INIS)

Sumathi, S.; Bhatia, S.; Lee, K.T.; Mohamed, A.R.

2010-01-01

This work examines the impregnated carbon-based sorbents for simultaneous removal of SO 2 and NOx from simulated flue gas. The carbon-based sorbents were prepared using palm shell activated carbon (PSAC) impregnated with several metal oxides (Ni, V, Fe and Ce). The removal of SO 2 and NOx from the simulated flue gas was investigated in a fixed-bed reactor. The results showed that PSAC impregnated with CeO 2 (PSAC-Ce) reported the highest sorption capacity among other impregnated metal oxides for the simultaneous removal of SO 2 and NOx. PSAC-Ce showed the longest breakthrough time of 165 and 115 min for SO 2 and NOx, respectively. The properties of the pure and impregnated PSAC were analyzed by BET, FTIR and XRF. The physical-chemical features of the PSAC-Ce sorbent indicated a catalytic activity in both the sorption of SO 2 and NOx. The formation of both sulfate (SO 4 2- ) and nitrate (NO 3- ) species on spent PSAC-Ce further prove the catalytic role played by CeO 2 .

Nox4 Is Dispensable for Exercise Induced Muscle Fibre Switch.

Directory of Open Access Journals (Sweden)

Juri Vogel

Full Text Available By producing H2O2, the NADPH oxidase Nox4 is involved in differentiation of mesenchymal cells. Exercise alters the composition of slow and fast twitch fibres in skeletal. Here we hypothesized that Nox4 contributes to exercise-induced adaptation such as changes in muscle metabolism or muscle fibre specification and studied this in wildtype and Nox4-/- mice.Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill induced a switch from fast twitch to intermediate fibres. However the induced muscle fibre switch was similar between Nox4-/- and wildtype mice. The same held true for exercise-induced expression of PGC1α or AMPK activation. Both are increased in response to exercise, but with no difference was observed between wildtype and Nox4-/- mice.Thus, exercise-induced muscle fibre switch is Nox4-independent.

Characteristics of fundamental combustion and NOx emission using various rank coals.

Science.gov (United States)

Kim, Sung Su; Kang, Youn Suk; Lee, Hyun Dong; Kim, Jae-Kwan; Hong, Sung Chang

2011-03-01

Eight types of coals of different rank were selected and their fundamental combustion characteristics were examined along with the conversion of volatile nitrogen (N) to nitrogen oxides (NOx)/fuel N to NOx. The activation energy, onset temperature, and burnout temperature were obtained from the differential thermogravimetry curve and Arrhenius plot, which were derived through thermo-gravimetric analysis. In addition, to derive the combustion of volatile N to NOx/fuel N to NOx, the coal sample, which was pretreated at various temperatures, was burned, and the results were compared with previously derived fundamental combustion characteristics. The authors' experimental results confirmed that coal rank was highly correlated with the combustion of volatile N to NOx/fuel N to NOx.

METHANE de-NOX FOR UTILITY PC BOILERS

Energy Technology Data Exchange (ETDEWEB)

Joseph Rabovitser

2000-07-05

The overall project objective is the development and validation of an innovative combustion system, based on a novel coal preheating concept prior to combustion, that can reduce NO{sub x} emissions to 0.15 lb/million Btu or less on utility pulverized coal (PC) boilers. This NO{sub x} reduction should be achieved without loss of boiler efficiency or operating stability, and at more than 25% lower levelized cost than state-of-the-art SCR technology. A further objective is to make this technology ready for full-scale commercial deployment by 2002-2003 in order to meet an anticipated market demand for NO{sub x} reduction technologies resulting from the EPA's NO{sub x} SIP call.

Energy from Waste--clean, efficient, renewable: transitions in combustion efficiency and NOx control.

Science.gov (United States)

Waldner, M H; Halter, R; Sigg, A; Brosch, B; Gehrmann, H J; Keunecke, M

2013-02-01

Traditionally EfW (Energy from Waste) plants apply a reciprocating grate to combust waste fuel. An integrated steam generator recovers the heat of combustion and converts it to steam for use in a steam turbine/generator set. This is followed by an array of flue gas cleaning technologies to meet regulatory limitations. Modern combustion applies a two-step method using primary air to fuel the combustion process on the grate. This generates a complex mixture of pyrolysis gases, combustion gases and unused combustion air. The post-combustion step in the first pass of the boiler above the grate is intended to "clean up" this mixture by oxidizing unburned gases with secondary air. This paper describes modifications to the combustion process to minimize exhaust gas volumes and the generation of noxious gases and thus improving the overall thermal efficiency of the EfW plant. The resulting process can be coupled with an innovative SNCR (Selective Non-Catalytic Reduction) technology to form a clean and efficient solid waste combustion system. Measurements immediately above the grate show that gas compositions along the grate vary from 10% CO, 5% H(2) and 0% O(2) to essentially unused "pure" air, in good agreement with results from a mathematical model. Introducing these diverse gas compositions to the post combustion process will overwhelm its ability to process all these gas fractions in an optimal manner. Inserting an intermediate step aimed at homogenizing the mixture above the grate has shown to significantly improve the quality of combustion, allowing for optimized process parameters. These measures also resulted in reduced formation of NO(x) (nitrogenous oxides) due to a lower oxygen level at which the combustion process was run (2.6 vol% O(2,)(wet) instead of 6.0 vol% O(2,)(wet)). This reduction establishes optimal conditions for the DyNOR™ (Dynamic NO(x) Reduction) NO(x) reduction process. This innovative SNCR technology is adapted to situations typically

40 CFR 97.83 - Applying for NOX Budget opt-in permit.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applying for NOX Budget opt-in permit... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.83 Applying for NOX Budget opt-in permit. (a) Applying for initial NO X Budget opt...

Native Alanine Substitution in the Glycine Hinge Modulates Conformational Flexibility of Heme Nitric Oxide/Oxygen (H-NOX) Sensing Proteins.

Science.gov (United States)

Hespen, Charles W; Bruegger, Joel J; Guo, Yirui; Marletta, Michael A

2018-06-15

Heme nitric oxide/oxygen sensing (H-NOX) domains are direct NO sensors that regulate a variety of biological functions in both bacteria and eukaryotes. Previous work on H-NOX proteins has shown that upon NO binding, a conformational change occurs along two glycine residues on adjacent helices (termed the glycine hinge). Despite the apparent importance of the glycine hinge, it is not fully conserved in all H-NOX domains. Several H-NOX sensors from the family Flavobacteriaceae contain a native alanine substitution in one of the hinge residues. In this work, the effect of the increased steric bulk within the Ala-Gly hinge on H-NOX function was investigated. The hinge in Kordia algicida OT-1 ( Ka H-NOX) is composed of A71 and G145. Ligand-binding properties and signaling function for this H-NOX were characterized. The variant A71G was designed to convert the hinge region of Ka H-NOX to the typical Gly-Gly motif. In activity assays with its cognate histidine kinase (HnoK), the wild type displayed increased signal specificity compared to A71G. Increasing titrations of unliganded A71G gradually inhibits HnoK autophosphorylation, while increasing titrations of unliganded wild type H-NOX does not inhibit HnoK. Crystal structures of both wild type and A71G Ka H-NOX were solved to 1.9 and 1.6 Å, respectively. Regions of H-NOX domains previously identified as involved in protein-protein interactions with HnoK display significantly higher b-factors in A71G compared to wild-type H-NOX. Both biochemical and structural data indicate that the hinge region controls overall conformational flexibility of the H-NOX, affecting NO complex formation and regulation of its HnoK.

Impact of FCC regenerator design in the NOx emissions

Energy Technology Data Exchange (ETDEWEB)

Pereira, Hugo Borges; Sandes, Emanuel Freire; Gilbert, William Richard; Roncolatto, Rodolfo Eugenio; Gobbo, Rodrigo; Casavechia, Luiz Carlos; Candido, William Victor Carlos [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Bridi, Patricia Elaine [Possebon Engenharia, Sao Mateus do Sul, PR (Brazil)

2012-07-01

Fluid Catalytic Cracking (FCC) is the main point source of NOx in the refinery and it is responsible for at least 20% of the total NOx emissions from the refineries. The thermal NOx formation in the FCC regenerator is negligible. However, half of the feed nitrogen is converted to coke, and is burned in the regenerator. The majority of coke nitrogen is reduced to N2 and less than 10% is converted to NOx. This number may vary significantly with the oxygen excess in the flue gas and other operational conditions. With the purpose of evaluating the impact of different regenerator designs in NOx formation, several tests were carried out in the PETROBRAS FCC prototype unit. The test unit is equipped with adiabatic insulation and a CO boiler, allowing it to reproduce the heat balance of a commercial FCC and to operate either in full combustion or partial combustion. Two different designs of FCC regenerators were evaluated: single stage regenerator (the existing configuration) and two stage regenerator, with the catalyst bed divided into two sections by a structured packing baffle. It was observed in the tests that the combustion regime had a very strong effect on NOx formation. In full combustion, the effect of the FCC operating variables: excess oxygen, combustion promoter content in catalyst and regenerator design could be identified. The two stage configuration was capable of decreasing NOx emissions by 30%. In partial combustion, the effect of the CO-boiler variables on NOx emissions was overwhelming, but the use of the structured packing baffle was able to improve the catalyst regeneration.(author)

Nox2 in regulatory T cells promotes angiotensin II-induced cardiovascular remodeling.

Science.gov (United States)

Emmerson, Amber; Trevelin, Silvia Cellone; Mongue-Din, Heloise; Becker, Pablo D; Ortiz, Carla; Smyth, Lesley A; Peng, Qi; Elgueta, Raul; Sawyer, Greta; Ivetic, Aleksandar; Lechler, Robert I; Lombardi, Giovanna; Shah, Ajay M

2018-04-24

The superoxide-generating enzyme Nox2 contributes to hypertension and cardiovascular remodeling triggered by activation of the renin-angiotensin system. Multiple Nox2-expressing cells are implicated in angiotensin II (AngII)-induced pathophysiology, but the importance of Nox2 in leukocyte subsets is poorly understood. Here, we investigated the role of Nox2 in T cells, particularly Tregs. Mice globally deficient in Nox2 displayed increased numbers of Tregs in the heart at baseline whereas AngII-induced T-effector cell (Teffs) infiltration was inhibited. To investigate the role of Treg Nox2, we generated a mouse line with CD4-targeted Nox2 deficiency (Nox2fl/flCD4Cre+). These animals showed inhibition of AngII-induced hypertension and cardiac remodeling related to increased tissue-resident Tregs and reduction in infiltrating Teffs, including Th17 cells. The protection in Nox2fl/flCD4Cre+ mice was reversed by anti-CD25 Ab-depletion of Tregs. Mechanistically, Nox2-/y Tregs showed higher in vitro suppression of Teffs proliferation than WT Tregs, increased nuclear levels of FoxP3 and NF-κB, and enhanced transcription of CD25, CD39, and CD73. Adoptive transfer of Tregs confirmed that Nox2-deficient cells had greater inhibitory effects on AngII-induced heart remodeling than WT cells. These results identify a previously unrecognized role of Nox2 in modulating suppression of Tregs, which acts to enhance hypertension and cardiac remodeling.

Mercury emission, control and measurement from coal combustion

Energy Technology Data Exchange (ETDEWEB)

Pan, Wei-Ping [North China Electric Power Univ., Beijing (China). School of Energy and Power Engineering; Western Kentucky Univ., Bowling Green, KY (United States). Inst. for Combustion Science and Environmental Technology; Cao, Yan [Western Kentucky Univ., Bowling Green, KY (United States). Inst. for Combustion Science and Environmental Technology; Zhang, Kai [North China Electric Power Univ., Beijing (China). School of Energy and Power Engineering

2013-07-01

Coal-fired electric power generation accounts for 65% of U.S. emissions of sulfur dioxide (SO2), 22% of nitrogen oxides (NOx), and 37% of mercury (Hg). The proposed Clear Air Interstate Rule (CAIR) and Clean Air Mercury Rule (CAMR) will attempt to regulate these emissions using a cap-and-trade program to replace a number of existing regulatory requirements that will impact this industry over the next decade. Mercury emissions remain the largest source that has not yet been efficiently controlled, in part because this is one of the most expensive to control. Mercury is a toxic, persistent pollutant that accumulates in the food chain. During the coal combustion process, when both sampling and accurate measurements are challenging, we know that mercury is present in three species: elemental, oxidized and particulate. There are three basic types of mercury measurement methods: Ontario Hydro Method, mercury continuous emission monitoring systems (CEMS) and sorbent-based monitoring. Particulate mercury is best captured by electrostatic precipitators (ESP). Oxidized mercury is best captured in wet scrubbers. Elemental mercury is the most difficult to capture, but selective catalytic reduction units (SCRs) are able to convert elemental mercury to oxidized mercury allowing it to be captured by wet flue gas desulfurization (FGD). This works well for eastern coals with high chlorine contents, but this does not work well on the Wyoming Powder River Basin (PRB) coals. However, no good explanation for its mechanism, correlations of chlorine content in coal with SCR performance, and impacts of higher chlorine content in coal on FGD re-emission are available. The combination of SCR and FGD affords more than an 80% reduction in mercury emissions in the case of high chlorine content coals. The mercury emission results from different coal ranks, boilers, and the air pollution control device (APCD) in power plant will be discussed. Based on this UAEPA new regulation, most power plants

Reducing global NOx emissions: developing advanced energy and transportation technologies.

Science.gov (United States)

Bradley, Michael J; Jones, Brian M

2002-03-01

Globally, energy demand is projected to continue to increase well into the future. As a result, global NOx emissions are projected to continue on an upward trend for the foreseeable future as developing countries increase their standards of living. While the US has experienced improvements in reducing NOx emissions from stationary and mobile sources to reduce ozone, further progress is needed to reduce the health and ecosystem impacts associated with NOx emissions. In other parts of the world, (in developing countries in particular) NOx emissions have been increasing steadily with the growth in demand for electricity and transportation. Advancements in energy and transportation technologies may help avoid this increase in emissions if appropriate policies are implemented. This paper evaluates commercially available power generation and transportation technologies that produce fewer NOx emissions than conventional technologies, and advanced technologies that are on the 10-year commercialization horizon. Various policy approaches will be evaluated which can be implemented on the regional, national and international levels to promote these advanced technologies and ultimately reduce NOx emissions. The concept of the technology leap is offered as a possibility for the developing world to avoid the projected increases in NOx emissions.

Study on the Conversion of Fuel Nitrogen Into NOx

Directory of Open Access Journals (Sweden)

Raminta Plečkaitienė

2011-12-01

Full Text Available The aim of this work is to investigate NOx regularities combusting fuels having high concentration of nitrogen and to develop methods that will reduce the conversion of fuel nitrogen into NOx. There are three solutions to reducing NOx concentration: the combustion of fuel mixing it with other types of “clean” fuel containing small amounts of nitrogen, laundering fuel and the combustion of fuel using carbon additives. These solutions can help with reducing the amount of nitrogen in the wood waste of furniture by about 30% by washing fuel with water. Therefore, NOx value may decrease by about 35%.Article in Lithuanian

Serological markers suggest heterogeneity of effectiveness of malaria control interventions on Bioko Island, equatorial Guinea.

Directory of Open Access Journals (Sweden)

Jackie Cook

Full Text Available In order to control and eliminate malaria, areas of on-going transmission need to be identified and targeted for malaria control interventions. Immediately following intense interventions, malaria transmission can become more heterogeneous if interventions are more successful in some areas than others. Bioko Island, Equatorial Guinea, has been subject to comprehensive malaria control interventions since 2004. This has resulted in substantial reductions in the parasite burden, although this drop has not been uniform across the island.In 2008, filter paper blood samples were collected from 7387 people in a cross-sectional study incorporating 18 sentinel sites across Bioko, Equatorial Guinea. Antibodies were measured to P. falciparum Apical Membrane Antigen-1 (AMA-1 by Enzyme Linked Immunosorbent Assay (ELISA. Age-specific seropositivity rates were used to estimate seroconversion rates (SCR. Analysis indicated there had been at least a 60% decline in SCR in four out of five regions on the island. Changes in SCR showed a high degree of congruence with changes in parasite rate (PR and with regional reductions in all cause child mortality. The mean age adjusted concentration of anti-AMA-1 antibodies was mapped to identify areas where individual antibody responses were higher than expected. This approach confirmed the North West of the island as a major focus of continuing infection and an area where control interventions need to be concentrated or re-evaluated.Both SCR and PR revealed heterogeneity in malaria transmission and demonstrated the variable effectiveness of malaria control measures. This work confirms the utility of serological analysis as an adjunct measure for monitoring transmission. Age-specific seroprevalence based evidence of changes in transmission over time will be of particular value when no baseline data are available. Importantly, SCR data provide additional evidence to link malaria control activities to contemporaneous

Effects space velocity and gas velocity on DeNOx catalyst with HC reductant; HC tenka NOx kangen shokubai no kukan sokudo oyobi gas ryusoku no eikyo

Energy Technology Data Exchange (ETDEWEB)

Niimura, K.; Tsujimura, K.

1995-04-20

Discussions were given on the hydrocarbon added reduction catalyst method to reduce NOx in diesel engine exhaust gas. An experiment was carried out with actual exhaust gas from a diesel engine by using a copper ion exchanged zeolite catalyst that has been coated on a honeycomb type substrate, and using propylene as a reductant. When the catalyst volume was changed with the exhaust gas space velocity kept constant, the NOx conversion ratio decreased as the catalyst length is decreased, and the activity shifted to the lower temperature side. The NOx reduction efficiency increased if the faster the gas flow velocity. On the other hand, if the gas flow velocity is slow, the NOx reduction can be carried out with relatively small amount of the reductant. When the catalyst volume was changed with the passing gas amount kept constant, the NOx conversion ratio decreased largely if the catalyst length is decreased. Further, the NOx reduction characteristics shift to the higher temperature side. In the catalyst length direction, the NOx reduction activity shows a relatively uniform action. However, a detailed observation reveals that the reaction heat in the catalyst is transmitted to the wake improving the activity, hence the further down the flow, the NOx conversion ratio gets higher in efficiency. 5 refs., 5 figs., 3 tabs.

Impact of NOx and OH on secondary organic aerosol formation from β-pinene photooxidation

Directory of Open Access Journals (Sweden)

M. Sarrafzadeh

2016-09-01

Full Text Available In this study, the NOx dependence of secondary organic aerosol (SOA formation from photooxidation of the biogenic volatile organic compound (BVOC β-pinene was comprehensively investigated in the Jülich Plant Atmosphere Chamber. Consistent with the results of previous NOx studies we found increases of SOA yields with increasing [NOx] at low-NOx conditions ([NOx]0  <  30 ppb, [BVOC]0 ∕ [NOx]0  >  10 ppbC ppb−1. Furthermore, increasing [NOx] at high-NOx conditions ([NOx]0  >  30 ppb, [BVOC]0 ∕ [NOx]0  ∼  10 to  ∼  2.6 ppbC ppb−1 suppressed the SOA yield. The increase of SOA yield at low-NOx conditions was attributed to an increase of OH concentration, most probably by OH recycling in NO + HO2  →  NO2 + OH reaction. Separate measurements without NOx addition but with different OH primary production rates confirmed the OH dependence of SOA yields. After removing the effect of OH concentration on SOA mass growth by keeping the OH concentration constant, SOA yields only decreased with increasing [NOx]. Measuring the NOx dependence of SOA yields at lower [NO] ∕ [NO2] ratio showed less pronounced increase in both OH concentration and SOA yield. This result was consistent with our assumption of OH recycling by NO and to SOA yields being dependent on OH concentrations. Our results furthermore indicated that NOx dependencies vary for different NOx compositions. A substantial fraction of the NOx-induced decrease of SOA yields at high-NOx conditions was caused by NOx-induced suppression of new particle formation (NPF, which subsequently limits the particle surface where low volatiles condense. This was shown by probing the NOx dependence of SOA formation in the presence of seed particles. After eliminating the effect of NOx-induced suppression of NPF and NOx-induced changes of OH concentrations, the remaining effect of NOx on the SOA yield from �

Design of a periodically operated SCR reactor

International Nuclear Information System (INIS)

Kotter, M.; Lintz, H.G.; Turek, T.

1993-01-01

A new NO x abatement process uses the rotating Ljungstroem air heater of the power plant for the selective catalytic reduction (SCR) of nitrogen monoxide with ammonia. For this purpose the air heater elements are covered by a catalytically active layer. The transformation can be carried out by simple replacement of the original air heater elements. Thus nitrogen monoxide control is possible without requiring major modifications of existing power plant equipment. Two oxidic catalysts have been developed to be employed in the different temperature sections of the air heater. The activity of the catalysts has been quantified with the aid of laboratory scale experiments. The results can be described using a simple expression for the rate of the chemical reaction. NO conversion and NH 3 slip to be expected in a catalytically active Ljungstroem heat exchanger are calculated with a reactor model taking into account the gas phase mass transfer resistances. The calculations show that the proposed device can be used if the NO concentration in the flue gas does not exceed 300 ppm. Recently Kraftanlagen AG, Heidelberg, installed a catalyst air heater system at Mandalay Generating Station in Oxnard, California. The comparison of the predicted results with preliminary experimental data proves the validity of the chosen reactor model. Under the given conditions NO conversions of more than 60% can be achieved maintaining the NH 3 slip below the specified value of 10 ppm. (orig.). 19 figs., 35 refs [de

NOX4 mediates BMP4-induced upregulation of TRPC1 and 6 protein expressions in distal pulmonary arterial smooth muscle cells.

Directory of Open Access Journals (Sweden)

Qian Jiang

Full Text Available Our previous studies demonstrated that bone morphogenetic protein 4 (BMP4 mediated, elevated expression of canonical transient receptor potential (TRPC largely accounts for the enhanced proliferation in pulmonary arterial smooth muscle cells (PASMCs. In the present study, we sought to determine the signaling pathway through which BMP4 up-regulates TRPC expression.We employed recombinant human BMP4 (rhBMP4 to determine the effects of BMP4 on NADPH oxidase 4 (NOX4 and reactive oxygen species (ROS production in rat distal PASMCs. We also designed small interfering RNA targeting NOX4 (siNOX4 and detected whether NOX4 knockdown affects rhBMP4-induced ROS, TRPC1 and 6 expression, cell proliferation and intracellular Ca2+ determination in PASMCs.In rhBMP4 treated rat distal PASMCs, NOX4 expression was (226.73±11.13 %, and the mean ROS level was (123.65±1.62 % of that in untreated control cell. siNOX4 transfection significantly reduced rhBMP4-induced elevation of the mean ROS level in PASMCs. Moreover, siNOX4 transfection markedly reduced rhBMP4-induced elevation of TRPC1 and 6 proteins, basal [Ca2+]i and SOCE. Furthermore, compared with control group (0.21±0.001, the proliferation of rhBMP4 treated cells was significantly enhanced (0.41±0.001 (P<0.01. However, such increase was attenuated by knockdown of NOX4. Moreover, external ROS (H2O2 100 µM, 24 h rescued the effects of NOX4 knockdown, which included the declining of TRPC1 and 6 expression, basal intracellular calcium concentration ([Ca2+]i and store-operated calcium entry (SOCE, suggesting that NOX4 plays as an important mediator in BMP4-induced proliferation and intracellular calcium homeostasis.These results suggest that BMP4 may increase ROS level, enhance TRPC1 and 6 expression and proliferation by up-regulating NOX4 expression in PASMCs.

Suppression of new particle formation from monoterpene oxidation by NOx

Science.gov (United States)

Wildt, J.; Mentel, T. F.; Kiendler-Scharr, A.; Hoffmann, T.; Andres, S.; Ehn, M.; Kleist, E.; Müsgen, P.; Rohrer, F.; Rudich, Y.; Springer, M.; Tillmann, R.; Wahner, A.

2014-03-01

The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory setup. At high NOx conditions ([BVOC] / [NOx] 23 ppb) new particle formation was suppressed. Instead, photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. When [NO] was reduced back to levels below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF to be slowed by orders of magnitude compared to analogous experiments at low NOx conditions ([NOx] ~300 ppt), although OH concentrations were higher. Varying NO2 photolysis enabled showing that NO was responsible for suppression of NPF. This suggests that peroxy radicals are involved in NPF. The rates of NPF and photochemical ozone production were related by power law dependence with an exponent approaching -2. This exponent indicated that the overall peroxy radical concentration must have been similar when NPF occurred. Thus, permutation reactions of first-generation peroxy radicals cannot be the rate limiting step in NPF from monoterpene oxidation. It was concluded that permutation reactions of higher generation peroxy-radical-like intermediates limit the rate of new particle formation. In contrast to the strong effects on the particle numbers, the formation of particle mass was substantially less sensitive to NOx concentrations. If at all, yields were reduced by about an order of magnitude only at very high NOx concentrations.

Advanced In-Furnace NOx Control for Wall and Cyclone-Fired Boilers

International Nuclear Information System (INIS)

Sarv, Hamid

2009-01-01

A NO x minimization strategy for coal-burning wall-fired and cyclone boilers was developed that included deep air staging, innovative oxygen use, reburning, and advanced combustion control enhancements. Computational fluid dynamics modeling was applied to refine and select the best arrangements. Pilot-scale tests were conducted by firing an eastern high-volatile bituminous Pittsburgh No.8 coal at 5 million Btu/hr in a facility that was set up with two-level overfire air (OFA) ports. In the wall-fired mode, pulverized coal was burned in a geometrically scaled down version of the B and W DRB-4Z(reg sign) low-NO x burner. At a fixed overall excess air level of 17%, NO x emissions with single-level OFA ports were around 0.32 lb/million Btu at 0.80 burner stoichiometry. Two-level OFA operation lowered the NO x levels to 0.25 lb/million Btu. Oxygen enrichment in the staged burner reduced the NO x values to 0.21 lb/million Btu. Oxygen enrichment plus reburning and 2-level OFA operation further curbed the NO x emissions to 0.19 lb/million Btu or by 41% from conventional air-staged operation with single-level OFA ports. In the cyclone firing arrangement, oxygen enrichment of the cyclone combustor enabled high-temperature and deeply staged operation while maintaining good slag tapping. Firing the Pittsburgh No.8 coal in the optimum arrangement generated 112 ppmv NO x (0.15 lb/million Btu) and 59 ppmv CO. The optimum emissions results represent 88% NO x reduction from the uncontrolled operation. Levelized costs for additional NO x removal by various in-furnace control methods in reference wall-fired or cyclone-fired units already equipped with single-level OFA ports were estimated and compared with figures for SCR systems achieving 0.1 lb NO x /10 6 Btu. Two-level OFA ports could offer the most economical approach for moderate NO x control, especially for smaller units. O 2 enrichment in combination with 2-level OFA was not cost effective for wall-firing. For cyclone units

DESIGN REPORT: LOW-NOX BURNERS FOR PACKAGE BOILERS

Science.gov (United States)

The report describes a low-NOx burner design, presented for residual-oil-fired industrial boilers and boilers cofiring conventional fuels and nitrated hazardous wastes. The burner offers lower NOx emission levels for these applications than conventional commercial burners. The bu...

Both cardiomyocyte and endothelial cell Nox4 mediate protection against hemodynamic overload-induced remodelling.

Science.gov (United States)

Zhang, Min; Mongue-Din, Heloise; Martin, Daniel; Catibog, Norman; Smyrnias, Ioannis; Zhang, Xiaohong; Yu, Bin; Wang, Minshu; Brandes, Ralf P; Schröder, Katrin; Shah, Ajay M

2018-03-01

NADPH oxidase-4 (Nox4) is an important reactive oxygen species (ROS) source that is upregulated in the haemodynamically overloaded heart. Our previous studies using global Nox4 knockout (Nox4KO) mice demonstrated a protective role of Nox4 during chronic abdominal aortic banding, involving a paracrine enhancement of myocardial capillary density. However, other authors who studied cardiac-specific Nox4KO mice reported detrimental effects of Nox4 in response to transverse aortic constriction (TAC). It has been speculated that these divergent results are due to cell-specific actions of Nox4 (i.e. cardiomyocyte Nox4 detrimental but endothelial Nox4 beneficial) and/or differences in the model of pressure overload (i.e. abdominal banding vs. TAC). This study aimed to (i) investigate whether the effects of Nox4 on pressure overload-induced cardiac remodelling vary according to the pressure overload model and (ii) compare the roles of cardiomyocyte vs. endothelial cell Nox4. Global Nox4KO mice subjected to TAC developed worse cardiac remodelling and contractile dysfunction than wild-type littermates, consistent with our previous results with abdominal aortic banding. Next, we generated inducible cardiomyocyte-specific Nox4 KO mice (Cardio-Nox4KO) and endothelial-specific Nox4 KO mice (Endo-Nox4KO) and studied their responses to pressure overload. Both Cardio-Nox4KO and Endo-Nox4KO developed worse pressure overload-induced cardiac remodelling and dysfunction than wild-type littermates, associated with significant decrease in protein levels of HIF1α and VEGF and impairment of myocardial capillarization. Cardiomyocyte as well as endothelial cell Nox4 contributes to protection against chronic hemodynamic overload-induced cardiac remodelling, at least in part through common effects on myocardial capillary density. © The Author 2017 Published by Oxford University Press on behalf of the European Society of Cardiology.

Low NOx combustion technologies for high-temperature natural gas combustion

International Nuclear Information System (INIS)

Flamme, Michael

1999-01-01

Because of the high process temperature which is required for some processes like glass melting and the high temperature to which the combustion air is preheated, NOx emission are extremely high. Even at these high temperatures, NOx emissions could be reduced drastically by using advanced combustion techniques such as staged combustion or flame-less oxidation, as experimental work has shown. In the case of oxy-fuel combustion, the NOx emission are also very high if conventional burners are used. The new combustion techniques achieve similar NOx reductions. (author)

Lifetime and production rate of NOx in the upper stratosphere and lower mesosphere in the polar spring/summer after the solar proton event in October–November 2003

Directory of Open Access Journals (Sweden)

F. Friederich

2013-03-01

Full Text Available We present altitude-dependent lifetimes of NOx, determined with MIPAS/ENVISAT (the Michelson Interferometer for Passive Atmospheric Sounding/the European Environment Satellite, for the Southern polar region after the solar proton event in October–November 2003. Between 50° S and 90° S and decreasing in altitude they range from about two days at 64 km to about 20 days at 44 km. The lifetimes are controlled by transport, mixing and photochemistry. We infer estimates of dynamical lifetimes by comparison of the observed decay to photochemical lifetimes calculated with the SLIMCAT 3-D Model. Photochemical loss contributes to the observed NOx depletion by 0.1% at 44 km, increasing with altitude to 45% at 64 km. In addition, we show the correlation of modelled ionization rates and observed NOx densities under consideration of the determined lifetimes of NOx, and calculate altitude-dependent effective production rates of NOx due to ionization. For that we compare ionization rates of the AIMOS data base with the MIPAS measurements from 15 October–31 December 2003. We derive effective NOx-production rates to be applied to the AIMOS ionization rates which range from about 0.2 NOx-molecules per ion pair at 44 km to 0.7 NOx-molecules per ion pair at 62 km. These effective production rates are considerably lower than predicted by box model simulations which could hint at an overestimation of the modelled ionization rates.

Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx

International Nuclear Information System (INIS)

Sarah C. Larson; Vicki H. Grassian

2006-01-01

Nanocrystalline zeolites with discrete crystal sizes of less than 100 nm have different properties relative to zeolites with larger crystal sizes. Nanocrystalline zeolites have improved mass transfer properties and very large internal and external surface areas that can be exploited for many different applications. The additional external surface active sites and the improved mass transfer properties of nanocrystalline zeolites offer significant advantages for selective catalytic reduction (SCR) catalysis with ammonia as a reductant in coal-fired power plants relative to current zeolite based SCR catalysts. Nanocrystalline NaY was synthesized with a crystal size of 15-20 nm and was thoroughly characterized using x-ray diffraction, electron paramagnetic resonance spectroscopy, nitrogen adsorption isotherms and Fourier Transform Infrared (FT-IR) spectroscopy. Copper ions were exchanged into nanocrystalline NaY to increase the catalytic activity. The reactions of nitrogen dioxides (NO x ) and ammonia (NH 3 ) on nanocrystalline NaY and CuY were investigated using FT-IR spectroscopy. Significant conversion of NO 2 was observed at room temperature in the presence of NH 3 as monitored by FT-IR spectroscopy. Copper-exchanged nanocrystalline NaY was more active for NO 2 reduction with NH 3 relative to nanocrystalline NaY

40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.

Science.gov (United States)

2010-07-01

... Trading Program. 97.386 Section 97.386 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program...

Size- and shape-controlled synthesis and catalytic performance of iron-aluminum mixed oxide nanoparticles for NOX and SO₂ removal with hydrogen peroxide.

Science.gov (United States)

Ding, Jie; Zhong, Qin; Zhang, Shule; Cai, Wei

2015-01-01

A novel, simple, reproducible and low-cost strategy is introduced for the size- and shape-controlled synthesis of iron-aluminum mixed oxide nanoparticles (NIAO(x/y)). The as-synthesized NIAO(x/y) catalyze decomposition of H2O2 yielding highly reactive hydroxyl radicals (OH) for NOX and SO2 removal. 100% SO2 removal is achieved. NIAO(x/y) with Fe/Al molar ratio of 7/3 (NIAO(7/3)) shows the highest NOX removal of nearly 80% at >170°C, whereas much lower NOX removal (oxides in NIAO(7/3) promotes the formation of lamellar products, thus improving the specific surface areas and mesoporous distribution, benefiting the production of OH radicals. Furthermore, the NIAO(7/3) leads to the minor increase of points of zero charges (PZC), apparent enhancement of FeOH content and high oxidizing ability of Fe(III), further improving the production of OH radicals. However, the NIAO(3/7) results in the formation of aluminum surface-enriched spherical particles, thus decreasing the surface atomic ratio of iron oxides, decreasing OH radical production. More importantly, the generation of FeOAl causes the decline of active sites. Finally, the catalytic decomposition of H2O2 on NIAO(x/y) is proposed. And the well catalytic stability of NIAO(7/3) is obtained for evaluation of 30 h. Copyright © 2014 Elsevier B.V. All rights reserved.

Nox regulation of smooth muscle contraction

OpenAIRE

Ritsick, Darren R.; Edens, William A.; Finnerty, Victoria; Lambeth, J. David

2007-01-01

The catalytic subunit, gp91phox (a.k.a., Nox2) of the NADPH-oxidase of mammalian phagocytes is activated by microbes and immune mediators to produce large amounts of reactive oxygen species (ROS) which participate in microbial killing. Homologs of gp91phox, the Nox and Duox enzymes, were recently described in a range of organisms, including plants, vertebrates, and invertebrates such as Drosophila melanogaster. While their enzymology and cell biology is being extensively studied in many labor...

Mathematical optimization techniques for managing selective catalytic reduction for a fleet of coal-fired power plants

Science.gov (United States)

Alanis Pena, Antonio Alejandro

Major commercial electricity generation is done by burning fossil fuels out of which coal-fired power plants produce a substantial quantity of electricity worldwide. The United States has large reserves of coal, and it is cheaply available, making it a good choice for the generation of electricity on a large scale. However, one major problem associated with using coal for combustion is that it produces a group of pollutants known as nitrogen oxides (NO x). NOx are strong oxidizers and contribute to ozone formation and respiratory illness. The Environmental Protection Agency (EPA) regulates the quantity of NOx emitted to the atmosphere in the United States. One technique coal-fired power plants use to reduce NOx emissions is Selective Catalytic Reduction (SCR). SCR uses layers of catalyst that need to be added or changed to maintain the required performance. Power plants do add or change catalyst layers during temporary shutdowns, but it is expensive. However, many companies do not have only one power plant, but instead they can have a fleet of coal-fired power plants. A fleet of power plants can use EPA cap and trade programs to have an outlet NOx emission below the allowances for the fleet. For that reason, the main aim of this research is to develop an SCR management mathematical optimization methods that, with a given set of scheduled outages for a fleet of power plants, minimizes the total cost of the entire fleet of power plants and also maintain outlet NO x below the desired target for the entire fleet. We use a multi commodity network flow problem (MCFP) that creates edges that represent all the SCR catalyst layers for each plant. This MCFP is relaxed because it does not consider average daily NOx constraint, and it is solved by a binary integer program. After that, we add the average daily NOx constraint to the model with a schedule elimination constraint (MCFPwSEC). The MCFPwSEC eliminates, one by one, the solutions that do not satisfy the average daily

RETROFIT COSTS FOR SO2 AND NOX CONTROL OPTIONS AT 200 COAL-FIRED PLANTS, VOLUME II - SITE SPECIFIC STUDIES FOR AL, DE. FL, GA, IL

Science.gov (United States)

The report gives results of a study, the objective of which was to significantly improve engineering cost estimates currently being used to evaluate the economic effects of applying SO2 and NOx controls at 200 large SO2-emitting coal-fired utility plants. To accomplish the object...

The Gothenburg Protocol: NOx emissions problematic for Norway

International Nuclear Information System (INIS)

Lind, Oddvar

2000-01-01

The Gothenburg Protocol concerns long-range air pollution and is a continuation of earlier protocols and agreements. Its recommendations are based on calculations of where the greatest possible health- and environmental impact is obtained per dollar invested. European countries have done much to reduce the emission of sulphur dioxide. Norway and most other countries, however, have difficulties reducing their emissions of nitrogen oxides. In Norway, the emission of sulphur dioxide must also be substantially reduced, as the tolerance limit for SO2 in nature is low. It is socio-economically profitable for Norway to conform to the Gothenburg Protocol. One of the largest environmental problems in Norway is acid rain and death of fish. Although it is difficult to calculate the exact values of fishing-lakes and of reduced health injuries when the emissions of harmful waste gases are reduced, the profit is very high. 90% of the SO2 pollution in Norway is long-range transported from abroad. Yet Norway must reduce the domestic emissions from 30 000 to 22 000 tonnes the next 10 years. Most of the present emission of SO2 in Norway comes from the production of metals. The reduction goal can be achieved by a combination of improving industrial processes, SO2 cleaning, and reducing the sulphur content of oil. In many European countries, the greatest problem is the increasing emission of NOx and formation of ozone at the ground, which is largely due to the rapidly increasing motor traffic. In Norway, most of the NOx emission comes from the coastal traffic and the fishing fleet, followed by the motor traffic, the petroleum industry and the processing industry. The most cost-effective NOx reductions can be obtained in the North Sea by installing low-NOx gas turbines. In ships, catalytic cleaning of NOx and engine improvements will contribute. On land, the goods traffic can be made more efficient. Most of the emission of ammonia comes from agriculture, where special measures are

Inversion of CO and NOx emissions using the adjoint of the IMAGES model

Directory of Open Access Journals (Sweden)

J.-F. Müller

2005-01-01

Full Text Available We use ground-based observations of CO mixing ratios and vertical column abundances together with tropospheric NO2 columns from the GOME satellite instrument as constraints for improving the global annual emission estimates of CO and NOx for the year 1997. The agreement between concentrations calculated by the global 3-dimensional CTM IMAGES and the observations is optimized using the adjoint modelling technique, which allows to invert for CO and NOx fluxes simultaneously, taking their chemical interactions into account. Our analysis quantifies a total of 39 flux parameters, comprising anthropogenic and biomass burning sources over large continental regions, soil and lightning emissions of NOx, biogenic emissions of CO and non-methane hydrocarbons, as well as the deposition velocities of both CO and NOx. Comparison between observed, prior and optimized CO mixing ratios at NOAA/CMDL sites shows that the inversion performs well at the northern mid- and high latitudes, and that it is less efficient in the Southern Hemisphere, as expected due to the scarsity of measurements over this part of the globe. The inversion, moreover, brings the model much closer to the measured NO2 columns over all regions. Sensitivity tests show that anthropogenic sources exhibit weak sensitivity to changes of the a priori errors associated to the bottom-up inventory, whereas biomass burning sources are subject to a strong variability. Our best estimate for the 1997 global top-down CO source amounts to 2760 Tg CO. Anthropogenic emissions increase by 28%, in agreement with previous inverse modelling studies, suggesting that the present bottom-up inventories underestimate the anthropogenic CO emissions in the Northern Hemisphere. The magnitude of the optimized NOx global source decreases by 14% with respect to the prior, and amounts to 42.1 Tg N, out of which 22.8 Tg N are due to anthropogenic sources. The NOx emissions increase over Tropical regions, whereas they decrease

Implications of diesel emissions control failures to emission factors and road transport NOx evolution

NARCIS (Netherlands)

Ntziachristos, L.; Papadimitriou, G.; Ligterink, N.; Hausberger, S.

2016-01-01

Diesel NOx emissions have been at the forefront of research and regulation scrutiny as a result of failures of late vehicle technologies to deliver on-road emissions reductions. The current study aims at identifying the actual emissions levels of late light duty vehicle technologies, including Euro

Evolutionary origin and function of NOX4-art, an arthropod specific NADPH oxidase.

Science.gov (United States)

Gandara, Ana Caroline Paiva; Torres, André; Bahia, Ana Cristina; Oliveira, Pedro L; Schama, Renata

2017-03-29

NADPH oxidases (NOX) are ROS producing enzymes that perform essential roles in cell physiology, including cell signaling and antimicrobial defense. This gene family is present in most eukaryotes, suggesting a common ancestor. To date, only a limited number of phylogenetic studies of metazoan NOXes have been performed, with few arthropod genes. In arthropods, only NOX5 and DUOX genes have been found and a gene called NOXm was found in mosquitoes but its origin and function has not been examined. In this study, we analyzed the evolution of this gene family in arthropods. A thorough search of genomes and transcriptomes was performed enabling us to browse most branches of arthropod phylogeny. We have found that the subfamilies NOX5 and DUOX are present in all arthropod groups. We also show that a NOX gene, closely related to NOX4 and previously found only in mosquitoes (NOXm), can also be found in other taxonomic groups, leading us to rename it as NOX4-art. Although the accessory protein p22-phox, essential for NOX1-4 activation, was not found in any of the arthropods studied, NOX4-art of Aedes aegypti encodes an active protein that produces H 2 O 2 . Although NOX4-art has been lost in a number of arthropod lineages, it has all the domains and many signature residues and motifs necessary for ROS production and, when silenced, H 2 O 2 production is considerably diminished in A. aegypti cells. Combining all bioinformatic analyses and laboratory work we have reached interesting conclusions regarding arthropod NOX gene family evolution. NOX5 and DUOX are present in all arthropod lineages but it seems that a NOX2-like gene was lost in the ancestral lineage leading to Ecdysozoa. The NOX4-art gene originated from a NOX4-like ancestor and is functional. Although no p22-phox was observed in arthropods, there was no evidence of neo-functionalization and this gene probably produces H 2 O 2 as in other metazoan NOX4 genes. Although functional and present in the genomes of many

Catalysts for Environmental Remediation

DEFF Research Database (Denmark)

Abrams, B. L.; Vesborg, Peter Christian Kjærgaard

2013-01-01

The properties of catalysts used in environmental remediation are described here through specific examples in heterogeneous catalysis and photocatalysis. In the area of heterogeneous catalysis, selective catalytic reduction (SCR) of NOx was used as an example reaction with vanadia and tungsta...

Constitutive NADPH-Dependent Electron Transferase Activity of the Nox4 Dehydrogenase Domain?

OpenAIRE

Nisimoto, Yukio; Jackson, Heather M.; Ogawa, Hisamitsu; Kawahara, Tsukasa; Lambeth, J. David

2010-01-01

NADPH oxidase 4 (Nox4) is constitutively active, while Nox2 requires the cytosolic regulatory subunits p47 phox and p67 phox and activated Rac with activation by phorbol 12-myristate 13-acetate (PMA). This study was undertaken to identify the domain on Nox4 that confers constitutive activity. Lysates from Nox4-expressing cells exhibited constitutive NADPH- but not NADH-dependent hydrogen peroxide production with a K m for NADPH of 55 ? 10 ?M. The concentration of Nox4 in cell lysates was esti...

Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration

Science.gov (United States)

Zhang, Lei; Wen, Xin; Lei, Zhang; Gao, Long; Sha, Xiangling; Ma, Zhenhua; He, Huibin; Wang, Yusu; Jia, Yang; Li, Yonghui

2018-04-01

Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction) was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction), SEM (scanning electron microscope), BET test and transient test. The experiments show that: * The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. * The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO2 is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO2, calcined at 350°Cfor 3h. * The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH3 is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N2, H2O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O2 to regenerate Mn4+.

Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration

Directory of Open Access Journals (Sweden)

Lei Zhang

2018-04-01

Full Text Available Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction, SEM (scanning electron microscope, BET test and transient test. The experiments show that: ① The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. ② The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO2 is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO2, calcined at 350°Cfor 3h. ③ The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH3 is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N2, H2O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O2 to regenerate Mn4+.

FIELD EVALUATION OF LOW-EMISSION COAL BURNER TECHNOLOGY ON UTILITY BOILERS VOLUME II. SECOND GENERATION LOW-NOX BURNERS

Science.gov (United States)

The report describes tests to evaluate the performance characteristics of three Second Generation Low-NOx burner designs: the Dual Register burner (DRB), the Babcock-Hitachi NOx Reducing (HNR) burner, and the XCL burner. The three represent a progression in development based on t...

Novel p47(phox)-related organizers regulate localized NADPH oxidase 1 (Nox1) activity.

Science.gov (United States)

Gianni, Davide; Diaz, Begoña; Taulet, Nicolas; Fowler, Bruce; Courtneidge, Sara A; Bokoch, Gary M

2009-09-15

The mechanisms that determine localized formation of reactive oxygen species (ROS) through NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase (Nox) family members in nonphagocytic cells are unknown. We show that the c-Src substrate proteins Tks4 (tyrosine kinase substrate with four SH3 domains) and Tks5 are functional members of a p47(phox)-related organizer superfamily. Tks proteins selectively support Nox1 and Nox3 (and not Nox2 and Nox4) activity in reconstituted cellular systems and interact with the NoxA1 activator protein through an Src homology 3 domain-mediated interaction. Endogenous Tks4 is required for Rac guanosine triphosphatase- and Nox1-dependent ROS production by DLD1 colon cancer cells. Our results are consistent with the Tks-mediated recruitment of Nox1 to invadopodia that form in DLD1 cells in a Tks- and Nox-dependent fashion. We propose that Tks organizers represent previously unrecognized members of an organizer superfamily that link Nox to localized ROS formation.

Control strategies of atmospheric mercury emissions from coal-fired power plants in China.

Science.gov (United States)

Tian, Hezhong; Wang, Yan; Cheng, Ke; Qu, Yiping; Hao, Jiming; Xue, Zhigang; Chai, Fahe

2012-05-01

Atmospheric mercury (Hg) emission from coal is one of the primary sources of anthropogenic discharge and pollution. China is one of the few countries in the world whose coal consumption constitutes about 70% of total primary energy, and over half of coals are burned directly for electricity generation. Atmospheric emissions of Hg and its speciation from coal-fired power plants are of great concern owing to their negative impacts on regional human health and ecosystem risks, as well as long-distance transport. In this paper, recent trends of atmospheric Hg emissions and its species split from coal-fired power plants in China during the period of 2000-2007 are evaluated, by integrating each plant's coal consumption and emission factors, which are classified by different subcategories of boilers, particulate matter (PM) and sulfur dioxide (SO2) control devices. Our results show that the total Hg emissions from coal-fired power plants have begun to decrease from the peak value of 139.19 t in 2005 to 134.55 t in 2007, though coal consumption growing steadily from 1213.8 to 1532.4 Mt, which can be mainly attributed to the co-benefit Hg reduction by electrostatic precipitators/fabric filters (ESPs/FFs) and wet flue gas desulfurization (WFGD), especially the sharp growth in installation of WFGD both in the new and existing power plants since 2005. In the coming 12th five-year-plan, more and more plants will be mandated to install De-NO(x) (nitrogen oxides) systems (mainly selective catalytic reduction [SCR] and selective noncatalytic reduction [SNCR]) for minimizing NO(x) emission, thus the specific Hg emission rate per ton of coal will decline further owing to the much higher co-benefit removal efficiency by the combination of SCR + ESPs/FFs + WFGD systems. Consequently, SCR + ESPs/FFs + WFGD configuration will be the main path to abate Hg discharge from coal-fired power plants in China in the near future. However advanced specific Hg removal technologies are necessary

Development of a pilot fluidized bed combustion to NOx reduction using natural gas: characterization and dimensioning; Desenvolvimento de um combustor piloto a leito fluidizado para reducao de NOx usando gas natural: caracterizacao e dimensionamento

Energy Technology Data Exchange (ETDEWEB)

Santos, Douglas A.; Lucena, Sergio [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

2004-07-01

At the present time, the operation of combustion systems and the design of combustors continue being important problems in the Engineering, and don't involve just the size increase of combustors, but also changes of characteristics in the details of projects. The combustors applications are directly related to the needs, like: material transformation for heating, drying or incineration; and all have the inconvenience of emanating of pollutant gaseous (such like NOx). In combustion systems of gases, NOx is basically created in the reaction between nitrogen and oxygen to high temperatures ({approx} 1200 deg C). Below such conditions, the contribution of thermal NOx is recognisably small. The efficient reduction, safe control and economical elimination of pollutant emissions in the systems of burning are the main focuses of environmental legislation and concern to several industrialized countries, besides Brazil. Furthermore, in appeal at the Environmental Laws and at the rising consumption of combustible gases (Natural Gas), new technologies more attractive and economically viable have been studied, for example the combustion systems in fluidized bed. In this kind of system is possible to obtain high combustion efficiency at low temperatures ({approx} 900 deg C) with NOx reduction. In this work is intended of characterizing and dimensioning an industrial fluidized bed combustor that uses Natural Gas like feedstock in the combustion system, with smaller amounts of emitted NOx. (author)

ANALYSIS OF SEQUENCE POLYMORPHISM OF SCR CLASS I AND II ALLELES AND STUDY REGULATION OF THEIR EXPRESSION

Directory of Open Access Journals (Sweden)

Jana ŽALUDOVÁ

2012-06-01

Full Text Available Self-incompatibility (AI is a widespread mechanism used by flowering plants to prevent inbreeding depression and helps create and maintain genetic diversity within a species. Oilseed rape (Brassica napus L. and especially its modern varieties are characterized by high level of self-fertility. In an effort to increase the production current breeding is focused on the production of inbred lines for making the F1 hybrids and the self-incompatibility can be an interesting tool for production self- sterile lines. In Brassica napus, we found two recessive alleles of a gene SCR II. Different expression of both alleles does not correspond to phenotypic manifestation of self-incompatibility and we can assume that it is prevailed by repressor gene that does not lie on the S-locus. This is also reason, why the SCR gene cannot serve as a molecular marker of self-incompatibility in Brassica napus, although many authors believe that this gene is essential in AI reaction. Brassica napus belong to plants with complex genetic constitution, is composed by two genomes, A and C, which give the possibility of different interactions and makes it difficult to study compared with diploid B. rapa and B. oleracea. In further study it is therefore important to focus on the interactions between genes SCR, SRK and SLG, and their influence on others, such as supressor gene systems.

Exploring the roles of temperature and NOx on ozone production in the Sacramento urban plume

Science.gov (United States)

Lafranchi, B. W.; Cohen, R. C.

2009-12-01

We investigate the role of temperature and NOx (NOx = NO+NO2) on ozone (O3) production in the Sacramento urban plume over a stretch of seven years (2001-2007) using data collected at UC Blodgett Forest Research Station (a forested site in the Sierra Nevadas about 80 km downwind of Sacramento, CA) and at a series of California Air Resources Board (CARB) sites along the Sacramento-Blodgett transect. The consistent daytime wind patterns between the Central Valley of California and the foothills of the Sierra Nevada mountains permits the assumption of plume transport from downtown Sacramento, over the CARB monitoring sites in the eastern suburbs, and past the Blodgett Forest research site. While NOx emissions are limited primarily to the urban and suburban regions of the transect, biogenic volatile organic compound (VOC) emissions are significant throughout the transect, thus there is a fast transition from VOC-limited to NOx-limited as the plume travels away from the urban center, and we have the opportunity to analyze the differences in ozone production across these two chemical regimes. For this analysis, the Sacramento-Blodgett transect is separated into three segments: urban, suburban, and rural, defined by the locations of selected monitoring sites. Ozone concentrations across each segment are controlled by chemical production (Pchem) and loss (Lchem), deposition to surfaces (Ldep), and mixing with background air (Lmix). At an assumed deposition rate, mixing rate, and background O3 concentration, the net chemical flux of ozone (Pchem - Lchem) can be inferred from differences in ozone concentrations between adjacent monitoring sites. We show that ozone production rates, in general, increase with temperature. We also show that decreases in NOx emissions over the period from 2001-2007 have been effective at reducing ozone production at all points along the transect, but only on days where temperatures are highest. At low temperatures, this decrease is less apparent

Low-level NOx removal in ambient air by pulsed corona technology

NARCIS (Netherlands)

Beckers, F.J.C.M.; Hoeben, W.F.L.M.; Pemen, A.J.M.; Heesch, van E.J.M.

2013-01-01

Although removal of NOx by (pulsed) corona discharges has been thoroughly investigated for high concentrations of NOx in flue gas, removal of low levels in ambient air proves to be a difficult task. (Sub) ppm NOx levels exist in traffic tunnels due to accumulation of exhaust gases. The application

RETROFIT COSTS FOR SO2 AND NOX CONTROL OPTIONS AT 200 COAL-FIRED PLANTS, VOLUME III - SITE SPECIFIC STUDIES FOR IN, KY, MA, MD, MI, MN

Science.gov (United States)

The report gives results of a study, the objective of which was to significantly improve engineering cost estimates currently being used to evaluate the economic effects of applying SO2 and NOx controls at 200 large SO2-emitting coal-fired utility plants. To accomplish the object...

RETROFIT COSTS FOR SO2 AND NOX CONTROL OPTIONS AT 200 COAL-FIRED PLANTS, VOLUME V - SITE SPECIFIC STUDIES FOR PA, SC, TN, VA, WI, WV

Science.gov (United States)

The report gives results of a study, the objective of which was to significantly improve engineering cost estimates currently being used to evaluate the economic effects of applying SO2 and NOx controls at 200 large SO2-emitting coal-fired utility plants. To accomplish the object...

Selection of best impregnated palm shell activated carbon (PSAC) for simultaneous removal of SO{sub 2} and NOx

Energy Technology Data Exchange (ETDEWEB)

Sumathi, S.; Bhatia, S.; Lee, K.T. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Mohamed, A.R., E-mail: chrahman@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

2010-04-15

This work examines the impregnated carbon-based sorbents for simultaneous removal of SO{sub 2} and NOx from simulated flue gas. The carbon-based sorbents were prepared using palm shell activated carbon (PSAC) impregnated with several metal oxides (Ni, V, Fe and Ce). The removal of SO{sub 2} and NOx from the simulated flue gas was investigated in a fixed-bed reactor. The results showed that PSAC impregnated with CeO{sub 2} (PSAC-Ce) reported the highest sorption capacity among other impregnated metal oxides for the simultaneous removal of SO{sub 2} and NOx. PSAC-Ce showed the longest breakthrough time of 165 and 115 min for SO{sub 2} and NOx, respectively. The properties of the pure and impregnated PSAC were analyzed by BET, FTIR and XRF. The physical-chemical features of the PSAC-Ce sorbent indicated a catalytic activity in both the sorption of SO{sub 2} and NOx. The formation of both sulfate (SO{sub 4}{sup 2-}) and nitrate (NO{sup 3-}) species on spent PSAC-Ce further prove the catalytic role played by CeO{sub 2}.

An artificial intelligence heat rate/NOx optimization system for Ontario Hydro`s Lambton Generating Station

Energy Technology Data Exchange (ETDEWEB)

Luk, J.; Bachalo, K.; Henrikson, J. [Ontario Hydro, Toronto, ON (Canada); Roland, W.; Booth, R.C.; Parikh, N.; Radl, B. [Pegasus Technologies Ltd., Painesville, OH (United States)

1998-12-01

The utilization of artificial Intelligence (AI)-based software programs to optimize power plant operations by simultaneously improving heat rate performance and reducing NOx emissions was discussed. While many AI programs were initially used for demonstration purposes, they are now available for commercial use due to their promising results. In 1996, the Fossil Business Unit of Ontario Hydro initiated a study to evaluate AI technology as a tool for optimizing heat rate and NOx reduction in coal fired stations. Tests were conducted at Units 3 and 4 of the Lambton Generation Station, located just south of Sarnia, Ontario. The tests were conducted to examine three desirable options: (1) achieve at least 0.5 per cent improvement in heat rate concurrently with a NOx reduction of at least 5 per cent, (2) optimize on `heat rate` only with minimum improvement of 2 per cent, and optimize `minimal NOx` only with reduction target of 20 per cent or more, and (3) reach a collaborative agreement with a supplier to further explore and develop AI optimization applications for other advanced and more complex plant processes. Results indicated that NOx reduction and heat rate improvement are not contradictory goals. 15 refs., 1 fig.

Field test of available methods to measure remotely SOx and NOx emissions from ships

Science.gov (United States)

Balzani Lööv, J. M.; Alfoldy, B.; Gast, L. F. L.; Hjorth, J.; Lagler, F.; Mellqvist, J.; Beecken, J.; Berg, N.; Duyzer, J.; Westrate, H.; Swart, D. P. J.; Berkhout, A. J. C.; Jalkanen, J.-P.; Prata, A. J.; van der Hoff, G. R.; Borowiak, A.

2014-08-01

Methods for the determination of ship fuel sulphur content and NOx emission factors based on remote measurements have been compared in the harbour of Rotterdam and compared to direct stack emission measurements on the ferry Stena Hollandica. The methods were selected based on a review of the available literature on ship emission measurements. They were either optical (LIDAR, Differential Optical Absorption Spectroscopy (DOAS), UV camera), combined with model-based estimates of fuel consumption, or based on the so called "sniffer" principle, where SO2 or NOx emission factors are determined from simultaneous measurement of the increase of CO2 and SO2 or NOx concentrations in the plume of the ship compared to the background. The measurements were performed from stations at land, from a boat and from a helicopter. Mobile measurement platforms were found to have important advantages compared to the land-based ones because they allow optimizing the sampling conditions and sampling from ships on the open sea. Although optical methods can provide reliable results it was found that at the state of the art level, the "sniffer" approach is the most convenient technique for determining both SO2 and NOx emission factors remotely. The average random error on the determination of SO2 emission factors comparing two identical instrumental set-ups was 6%. However, it was found that apparently minor differences in the instrumental characteristics, such as response time, could cause significant differences between the emission factors determined. Direct stack measurements showed that about 14% of the fuel sulphur content was not emitted as SO2. This was supported by the remote measurements and is in agreement with the results of other field studies.

The enhancement of CuO modified V2O5-WO3/TiO2 based SCR catalyst for Hg° oxidation in simulated flue gas

Science.gov (United States)

Chen, Chuanmin; Jia, Wenbo; Liu, Songtao; Cao, Yue

2018-04-01

CuO modified V2O5-WO3/TiO2 based SCR catalysts prepared by improved impregnation method were investigated to evaluate the catalytic activity for elemental mercury (Hg°) oxidation in simulated flue gas at 150-400 °C. Nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. It was found that V0.8WTi-Cu3 catalyst exhibited the superior Hg° oxidation activity and wide operating temperature window at the gas hourly space velocity (GHSV) of 3 × 105 h-1. The BET and XRD results showed that CuO was well loaded and highly dispersed on the catalysts surface. The XPS results suggested that the addition of CuO generated abundant chemisorbed oxygen, which was due to the synergistic effect between CuO and V2O5. The existence of the redox cycle of V4+ + Cu2+ ↔ V5+ + Cu+ in V0.8WTi-Cu3 catalyst enhanced Hg° oxidation activity. The effects of flue gas components (O2, NO, SO2 and H2O) on Hg° oxidation over V0.8WTi-Cu3 catalyst were also explored. Moreover, the co-presence of NO and NH3 remarkably inhibited Hg° oxidation, which was due to the competitive adsorption and reduction effect of NH3 at SCR condition. Fortunately, this inhibiting effect was gradually scavenged with the decrease of GHSV. The mechanism of Hg° oxidation was also investigated.

Investigation of In-Cylinder Steam Injection in a Turbocharged Diesel Engine for Waste Heat Recovery and NOx Emission Control

OpenAIRE

Zhongbo Zhang; Lifu Li

2018-01-01

In this study, an in-cylinder steam injection method is introduced and applied to a turbocharged diesel engine for waste heat recovery and NOx emission reduction. In the method, cool water was first heated into superheated steam by exhaust. Then the superheated steam was directly injected into the cylinder during the compression stroke. The potential for fuel savings and NOx emission reduction obtained by this method was investigated. First, a two-zone combustion model for the baseline engine...

On-road assessment of light duty vehicles in Delhi city: Emission factors of CO, CO2 and NOX

Science.gov (United States)

Jaiprakash; Habib, Gazala

2018-02-01

This study presents the technology based emission factors of gaseous pollutants (CO, CO2, and NOX) measured during on-road operation of nine passenger cars of diesel, gasoline, and compressed natural gas (CNG). The emissions from two 3-wheelers, and three 2-wheelers were measured by putting the vehicles on jacks and operating them according to Modified Indian Driving Cycle (MIDC) at no load condition. The emission factors observed in the present work were significantly higher than values reported from dynamometer study by Automotive Research Association of India (ARAI). Low CO (0.34 ± 0.08 g km-1) and high NOX (1.0 ± 0.4 g km-1) emission factors were observed for diesel passenger cars, oppositely high CO (2.2 ± 2.6 g km-1) and low NOX (1.0 ± 1.6 g km-1) emission factors were seen for gasoline powered cars. The after-treatment technology in diesel vehicles was effective in CO reduction. While the use of turbocharger in diesel vehicles to generate high combustion temperature and pressure produces more NOx, probably which may not be effectively controlled by after-treatment device. The after-treatment devices in gasoline powered Post-2010, Post-2005 vehicles can be acclaimed for reduced CO emissions compared to Post-2000 vehicles. This work presents a limited data set of emission factors from on-road operations of light duty vehicles, this limitation can be improved by further measurements of emissions from similar vehicles.

STUDY OF MERCURY OXIDATION BY SCR CATALYST IN AN ENTRAINED-FLOW REACTOR UNDER SIMULATED PRB CONDITIONS

Science.gov (United States)

A bench-scale entrained-flow reactor system was constructed for studying elemental mercury oxidation under selective catalytic reduction (SCR) reaction conditions. Simulated flue gas was doped with fly ash collected from a subbituminous Powder River Basin (PRB) coal-fired boiler ...

The black rock series supported SCR catalyst for NO x removal.

Science.gov (United States)

Xie, Bin; Luo, Hang; Tang, Qing; Du, Jun; Liu, Zuohua; Tao, Changyuan

2017-09-01

Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO 2 -TiO 2 sols and regulating its catalytic active constituents with V 2 O 5 and MoO 3 . Consequently, 90% NO removal ratio was obtained within 300-400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR), and NH 3 -temperature programmed desorption (NH 3 -TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NO x removal, including highly dispersed active components, abundant surface-adsorbed oxygen O α , well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO 2 -based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO 2 and H 2 O exceeding 85% at temperatures from 300 to 450 °C.

Observations of the temperature dependent response of ozone to NOx reductions in the Sacramento, CA urban plume

Science.gov (United States)

Lafranchi, B. W.; Goldstein, A. H.; Cohen, R. C.

2011-07-01

Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by 30 % between 2001 and 2008. Here we use an observation-based method to quantify net ozone (O3) production rates in the outflow from the Sacramento metropolitan region and examine the O3 decrease resulting from reductions in NOx emissions. This observational method does not rely on assumptions about detailed chemistry of ozone production, rather it is an independent means to verify and test these assumptions. We use an instantaneous steady-state model as well as a detailed 1-D plume model to aid in interpretation of the ozone production inferred from observations. In agreement with the models, the observations show that early in the plume, the NOx dependence for Ox (Ox = O3 + NO2) production is strongly coupled with temperature, suggesting that temperature-dependent biogenic VOC emissions and other temperature-related effects can drive Ox production between NOx-limited and NOx-suppressed regimes. As a result, NOx reductions were found to be most effective at higher temperatures over the 7 year period. We show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx concentrations (and presumably emissions) by an additional 30 % (relative to 2007 levels) will eliminate violations of the state 1 h standard in the region. If current trends continue, a 30 % decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the Sacramento region appears to be imminent.

A hybrid plasma-chemical system for high-NOx flue gas treatment

Science.gov (United States)

Chmielewski, Andrzej G.; Zwolińska, Ewa; Licki, Janusz; Sun, Yongxia; Zimek, Zbigniew; Bułka, Sylwester

2018-03-01

The reduction of high concentrations of NOx and SO2 from simulated flue gas has been studied. Our aim was to optimise energy consumption for NOx and SO2 removal from off-gases from a diesel generator using heavy fuel oil. A hybrid process: electron beam (EB) plasma and wet scrubber has been applied. A much higher efficiency of NOx and SO2 removal was achieved in comparison to dry, ammonia free, electron beam flue gas treatment (EBFGT). A recorded removal from a concentration of 1500 ppm NOx reached 49% at a low dose of 6.5 kGy, while only 2% NOx was removed at the same dose if EB only was applied. For SO2, removal efficiency at a dose of 6.5 kGy increased from 15% (EB only) to 84% when sea water was used as a wet scrubber agent for 700 ppm SO2. The results of this study indicate that EB combined with wet scrubber is a very promising technology to be applied for removal of high concentrations of NOx and SO2 emitted from diesel engines operated e.g. on cargo ships, which are the main sources of SO2 and NOx pollution along their navigation routes.

Molecular evolution of the reactive oxygen-generating NADPH oxidase (Nox/Duox family of enzymes

Directory of Open Access Journals (Sweden)

Lambeth J David

2007-07-01

Full Text Available Abstract Background NADPH-oxidases (Nox and the related Dual oxidases (Duox play varied biological and pathological roles via regulated generation of reactive oxygen species (ROS. Members of the Nox/Duox family have been identified in a wide variety of organisms, including mammals, nematodes, fruit fly, green plants, fungi, and slime molds; however, little is known about the molecular evolutionary history of these enzymes. Results We assembled and analyzed the deduced amino acid sequences of 101 Nox/Duox orthologs from 25 species, including vertebrates, urochordates, echinoderms, insects, nematodes, fungi, slime mold amoeba, alga and plants. In contrast to ROS defense enzymes, such as superoxide dismutase and catalase that are present in prokaryotes, ROS-generating Nox/Duox orthologs only appeared later in evolution. Molecular taxonomy revealed seven distinct subfamilies of Noxes and Duoxes. The calcium-regulated orthologs representing 4 subfamilies diverged early and are the most widely distributed in biology. Subunit-regulated Noxes represent a second major subdivision, and appeared first in fungi and amoeba. Nox5 was lost in rodents, and Nox3, which functions in the inner ear in gravity perception, emerged the most recently, corresponding to full-time adaptation of vertebrates to land. The sea urchin Strongylocentrotus purpuratus possesses the earliest Nox2 co-ortholog of vertebrate Nox1, 2, and 3, while Nox4 first appeared somewhat later in urochordates. Comparison of evolutionary substitution rates demonstrates that Nox2, the regulatory subunits p47phox and p67phox, and Duox are more stringently conserved in vertebrates than other Noxes and Nox regulatory subunits. Amino acid sequence comparisons identified key catalytic or regulatory regions, as 68 residues were highly conserved among all Nox/Duox orthologs, and 14 of these were identical with those mutated in Nox2 in variants of X-linked chronic granulomatous disease. In addition to

Phenomenological modeling of combustion and NOx emissions using detailed tabulated chemistry methods in diesel engines

OpenAIRE

Rezaei, R.; Dinkelacker, F.; Tilch, B.; Delebinski, T.; Brauer, M.

2016-01-01

Enhancing the predictive quality of engine models, while maintaining an affordable computational cost, is of great importance. In this study, a phenomenological combustion and a tabulated NOx model, focusing on efficient modeling and improvement of computational effort, is presented. The proposed approach employs physical and chemical sub-models for local processes such as injection, spray formation, ignition, combustion, and NOx formation, being based on detailed tabulated chemistry methods....

Development of the Aqueous Processes for Removing NOx from Flue Gases.

Science.gov (United States)

Chappell, Gilford A.

A screening study was conducted to evaluate the capability of aqueous solutions to scrub NOx from the flue gases emitted by stationary power plants fired with fossil fuels. The report summarizes the findings of this laboratory program. The experimental program studied the following media for absorption of NOx from flue gases containing no NOx:…

Cardiac and renal upregulation of Nox2 and NF-κB and repression of Nox4 and Nrf2 in season- and diabetes-mediated models of vascular oxidative stress in guinea-pig and rat.

Science.gov (United States)

Gajos-Draus, Anna; Duda, Monika; Beręsewicz, Andrzej

2017-11-01

The superoxide-forming NADPH oxidase homologues, Nox1, Nox2, and Nox5, seem to mediate the pro-atherosclerotic vascular phenotype. The hydrogen peroxide-forming Nox4 afforded vascular protection, likely via NF-E2-related factor-2 (Nrf2) activation and/or Nox2 downregulation in transgenic mice. We hypothesized that oxidative stress in the intact vasculature involves, aside from the upregulation of the superoxide-forming Noxs, the downregulation of the Nox4/Nrf2 pathway. Guinea-pigs and rats were studied either in winter or in summer, and the streptozotocin diabetic rats in winter. Plasma nitrite, and superoxide production by isolated hearts were measured, while frozen tissues served in biochemical analyses. Summer in both species and diabetes in rats downregulated myocardial Nox4 while reciprocally upregulating Nox2 and Nox5 in guinea-pigs, and Nox2 in rats. Simultaneously, myocardial Nrf2 activity and the expression of the Nrf2-directed heme oxygenase-1 and endothelial NO synthase were reduced while activity of the nuclear factor κ B (NF- κ B) and the expression of NF- κ B-directed inducible NO synthase and the vascular cell adhesion molecule-1 were increased. Cardiac superoxide production was increased while plasma nitrite was decreased reciprocally. Analogous disregulation of Noxs, Nrf2, and NF- κ B, occurred in diabetic rat kidneys. Given the diversity of the experimental settings and the uniform pattern of the responses, we speculate that: (1) chronic vascular oxidative stress is a nonspecific (model-, species-, organ-independent) response involving the induction of Nox2 (and Nox5 in guinea-pigs) and the NF- κ B pathway, and the repression of Nox4 and the Nrf2 pathway; and (2) the systems Nox2-NF- κ B and Nox4-Nrf2 regulate each other negatively. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Aviation NOx-induced CH4 effect: Fixed mixing ratio boundary conditions versus flux boundary conditions

Science.gov (United States)

Khodayari, Arezoo; Olsen, Seth C.; Wuebbles, Donald J.; Phoenix, Daniel B.

2015-07-01

Atmospheric chemistry-climate models are often used to calculate the effect of aviation NOx emissions on atmospheric ozone (O3) and methane (CH4). Due to the long (∼10 yr) atmospheric lifetime of methane, model simulations must be run for long time periods, typically for more than 40 simulation years, to reach steady-state if using CH4 emission fluxes. Because of the computational expense of such long runs, studies have traditionally used specified CH4 mixing ratio lower boundary conditions (BCs) and then applied a simple parameterization based on the change in CH4 lifetime between the control and NOx-perturbed simulations to estimate the change in CH4 concentration induced by NOx emissions. In this parameterization a feedback factor (typically a value of 1.4) is used to account for the feedback of CH4 concentrations on its lifetime. Modeling studies comparing simulations using CH4 surface fluxes and fixed mixing ratio BCs are used to examine the validity of this parameterization. The latest version of the Community Earth System Model (CESM), with the CAM5 atmospheric model, was used for this study. Aviation NOx emissions for 2006 were obtained from the AEDT (Aviation Environmental Design Tool) global commercial aircraft emissions. Results show a 31.4 ppb change in CH4 concentration when estimated using the parameterization and a 1.4 feedback factor, and a 28.9 ppb change when the concentration was directly calculated in the CH4 flux simulations. The model calculated value for CH4 feedback on its own lifetime agrees well with the 1.4 feedback factor. Systematic comparisons between the separate runs indicated that the parameterization technique overestimates the CH4 concentration by 8.6%. Therefore, it is concluded that the estimation technique is good to within ∼10% and decreases the computational requirements in our simulations by nearly a factor of 8.

Quantifying the isotopic composition of NOx emission sources: An analysis of collection methods

Science.gov (United States)

Fibiger, D.; Hastings, M.

2012-04-01

We analyze various collection methods for nitrogen oxides, NOx (NO2 and NO), used to evaluate the nitrogen isotopic composition (δ15N). Atmospheric NOx is a major contributor to acid rain deposition upon its conversion to nitric acid; it also plays a significant role in determining air quality through the production of tropospheric ozone. NOx is released by both anthropogenic (fossil fuel combustion, biomass burning, aircraft emissions) and natural (lightning, biogenic production in soils) sources. Global concentrations of NOx are rising because of increased anthropogenic emissions, while natural source emissions also contribute significantly to the global NOx burden. The contributions of both natural and anthropogenic sources and their considerable variability in space and time make it difficult to attribute local NOx concentrations (and, thus, nitric acid) to a particular source. Several recent studies suggest that variability in the isotopic composition of nitric acid deposition is related to variability in the isotopic signatures of NOx emission sources. Nevertheless, the isotopic composition of most NOx sources has not been thoroughly constrained. Ultimately, the direct capture and quantification of the nitrogen isotopic signatures of NOx sources will allow for the tracing of NOx emissions sources and their impact on environmental quality. Moreover, this will provide a new means by which to verify emissions estimates and atmospheric models. We present laboratory results of methods used for capturing NOx from air into solution. A variety of methods have been used in field studies, but no independent laboratory verification of the efficiencies of these methods has been performed. When analyzing isotopic composition, it is important that NOx be collected quantitatively or the possibility of fractionation must be constrained. We have found that collection efficiency can vary widely under different conditions in the laboratory and fractionation does not vary

A procedure to identify and to assess risk parameters in a SCR (Steel Catenary Riser) due to the fatigue failure

Energy Technology Data Exchange (ETDEWEB)

Stefane, Wania [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Morooka, Celso K. [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Dept. de Engenharia de Petroleo. Centro de Estudos de Petroleo; Pezzi Filho, Mario [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). E and P. ENGP/IPMI/ES; Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

2009-12-19

The discovery of offshore fields in ultra deep water and the presence of reservoirs located in great depths below the seabed requires innovative solutions for offshore oil production systems. Many riser configurations have emerged as economically viable technological solutions for these scenarios. Therefore the study and the development of methodologies applied to riser design and procedures to calculate and to dimension production risers, taken into account the effects of mete ocean conditions, such as waves, current and platform motion in the fatigue failure is fundamental. The random nature of these conditions as well as the mechanical characteristics of the riser components are critical to a probabilistic treatment to ensure the greatest reliability for risers and minimum risks associated to different aspects of the operation like the safety of the installation, economical concerns and the environment. The current work presents a procedure of the identification and the assessment of main parameters of risk when considering fatigue failure. Static and dynamic behavior of Steel Catenary Riser (SCR) under the effects of mete ocean conditions and uncertainties related to total cumulative damage (Miner-Palmgren's rule) are taken into account. The methodology adopted is probabilistic and the approach is analytical. The procedure is based on the First Order Reliability Method (FORM) which usually presents low computational effort and acceptable accuracy. The procedure suggested is applied for two practical cases, one using data available from the literature and the second with data collected from an actual Brazilian offshore field operation. For both cases, results of the probability of failure due to fatigue were obtained for different locations along the SCR length connected to a semi-submersible platform. From these results, the sensitivity of the probability of failure due to fatigue for a SCR could be verified, and the most effective parameter could also be

Ozone Production and Control Strategies for Southern Taiwan

Science.gov (United States)

Shiu, C.; Liu, S.; Chang, C.; Chen, J.; Chou, C. C.; Lin, C.

2006-12-01

An observation-based modeling (OBM) approach is used to estimate the ozone production efficiency and production rate of O3 (P(O3)) in southern Taiwan. The approach can also provide an indirect estimate of the concentration of OH. Measured concentrations of two aromatic hydrocarbons, i.e. ethylbenzene/m,p-xylene, are used to estimate the degree of photochemical processing and the amounts of photochemically consumed NOx and NMHCs. In addition, a one-dimensional (1d) photochemical model is used to compare with the OBM results. The average ozone production efficiency during the field campaign in Kaohsiung-Pingtung area in Fall 2003 is found to be about 5, comparable to previous works. The relationship of P(O3) with NOx is examined in detail and compared to previous studies. The derived OH concentrations from this approach are in fair agreement with values calculated from the 1d photochemical model. The relationship of total oxidants (e.g. O3+NO2) versus initial NOx and NMHCs suggests that reducing NMHCs are more effective in controlling total oxidants than reducing NOx. For O3 control, reducing NMHC is even more effective than NOx due to the NO titration effect. This observation-based approach provides a good alternative for understanding the production of ozone and formulating ozone control strategy in urban and suburban environment without measurements of peroxy radicals.

Research and proposal on selective catalytic reduction reactor optimization for industrial boiler.

Science.gov (United States)

Yang, Yiming; Li, Jian; He, Hong

2017-08-24

The advanced computational fluid dynamics (CFD) software STAR-CCM+ was used to simulate a denitrification (De-NOx) project for a boiler in this paper, and the simulation result was verified based on a physical model. Two selective catalytic reduction (SCR) reactors were developed: reactor 1 was optimized and reactor 2 was developed based on reactor 1. Various indicators, including gas flow field, ammonia concentration distribution, temperature distribution, gas incident angle, and system pressure drop were analyzed. The analysis indicated that reactor 2 was of outstanding performance and could simplify developing greatly. Ammonia injection grid (AIG), the core component of the reactor, was studied; three AIGs were developed and their performances were compared and analyzed. The result indicated that AIG 3 was of the best performance. The technical indicators were proposed for SCR reactor based on the study. Flow filed distribution, gas incident angle, and temperature distribution are subjected to SCR reactor shape to a great extent, and reactor 2 proposed in this paper was of outstanding performance; ammonia concentration distribution is subjected to ammonia injection grid (AIG) shape, and AIG 3 could meet the technical indicator of ammonia concentration without mounting ammonia mixer. The developments above on the reactor and the AIG are both of great application value and social efficiency.

RETROFIT COSTS FOR SO2 AND NOX CONTROL OPTIONS AT 200 COAL-FIRED PLANTS, VOLUME IV - SITE SPECIFIC STUDIES FOR MO, MS, NC, NH, NJ, NY, OH

Science.gov (United States)

The report gives results of a study, the objective of which was to significantly improve engineering cost estimates currently being used to evaluate the economic effects of applying SO2 and NOx controls at 200 large SO2-emitting coal-fired utility plants. To accomplish the object...

Photocatalytic NO_x abatement. Theory, applications, current research, and limitations

International Nuclear Information System (INIS)

Bloh, Jonathan Z.

2017-01-01

Nitrogen oxides are one of the major air pollutants that threaten our air quality and health. As a consequence, increasingly stricter regulations are in place forcing action to reduce the concentration of these dangerous compounds. Conventional methods of reducing the NO_x pollution level are reducing the emission directly at the source or restrictive measures such as low emission zones. However, there are recent reports questioning the efficacy of the strategy to reduce ambient NO_x levels solely by reducing their emissions and existing threshold values are still frequently exceeded in many European cities. Semiconductor photocatalysis presents an appealing alternative capable of removing NO_x and other air pollutants from the air once they have already been released and dispersed. Recent field tests have shown that a reduction of a few percent in NO_x values is possible with available photocatalysts. Current research focuses on further increasing the catalysts' efficacy as well as their selectivity to suppress the formation of undesired by-products. Especially using these improved materials, photocatalytic NO_x abatement could prove a very valuable contributor to better air quality.

Novel p47phox-related organizers regulate NADPH oxidase 1 (Nox1) activity and localization

Science.gov (United States)

Gianni, Davide; Diaz, Begoña; Taulet, Nicolas; Fowler, Bruce; Courtneidge, Sara A.; Bokoch, Gary M.

2010-01-01

The mechanisms that determine localized formation of reactive oxygen species (ROS) via NADPH oxidases (Nox) in nonphagocytic cells are unknown. We show that the c-Src substrate proteins Tks4 and Tks5 are functional members of a p47phox-related organizer superfamily. Tks proteins selectively support Nox1 and Nox3 (vs. Nox2 and Nox4) activity in reconstituted cellular systems, and interact with the NoxA1 activator protein through an SH3-mediated interaction. Endogenous Tks4 is required for Rac GTPase-dependent ROS production by DLD1 colon cancer cells. Tks4 recruits Nox1 to invadopodia that form in DLD1 cells in a Tks- and Nox-dependent fashion. We propose that Tks organizers represent novel members of an organizer superfamily that link Nox to localized ROS formation. PMID:19755710

Single bank NOx adsorber for heavy duty diesel engines

NARCIS (Netherlands)

Genderen, M. van; Aken, M.G. van

2003-01-01

In a NOx adsorber programme the feasibility for applying this technology to heavy duty diesel engines was investigated. After modelling and simulations for realising best λ < 1 engine conditions a platform was build which was used to obtain good NOx adsorber regeneration settings in a number of

Software Defined Networking (SDN) controlled all optical switching networks with multi-dimensional switching architecture

Science.gov (United States)

Zhao, Yongli; Ji, Yuefeng; Zhang, Jie; Li, Hui; Xiong, Qianjin; Qiu, Shaofeng

2014-08-01

Ultrahigh throughout capacity requirement is challenging the current optical switching nodes with the fast development of data center networks. Pbit/s level all optical switching networks need to be deployed soon, which will cause the high complexity of node architecture. How to control the future network and node equipment together will become a new problem. An enhanced Software Defined Networking (eSDN) control architecture is proposed in the paper, which consists of Provider NOX (P-NOX) and Node NOX (N-NOX). With the cooperation of P-NOX and N-NOX, the flexible control of the entire network can be achieved. All optical switching network testbed has been experimentally demonstrated with efficient control of enhanced Software Defined Networking (eSDN). Pbit/s level all optical switching nodes in the testbed are implemented based on multi-dimensional switching architecture, i.e. multi-level and multi-planar. Due to the space and cost limitation, each optical switching node is only equipped with four input line boxes and four output line boxes respectively. Experimental results are given to verify the performance of our proposed control and switching architecture.

40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.

Science.gov (United States)

2010-07-01

... Trading Program. 96.386 Section 96.386 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR... Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...

Lightning NOx Production in CMAQ: Part II - Parameterization Based on Relationship between Observed NLDN Lightning Strikes and Modeled Convective Precipitation Rates