scholarly journals Numerical Simulation to Reduce NOx of Diesel Engine Urea-SCR System

2014 ◽  
Vol 8 (1) ◽  
pp. 643-647 ◽  
Author(s):  
Zhang Hui ◽  
Xu Boyan ◽  
Wang Chuansheng
Keyword(s):  
Concentration Distribution ◽  
Optimization Design ◽  
Catalytic Reduction ◽  
Reducing Agent ◽  
Fuel Injector ◽  
Scr Catalyst ◽  
Numerical Analytical Method ◽  
Scr System ◽  
The Mathematical Model ◽  
Good Agreement

By using computational fluid dynamics and chemical reaction dynamics method, the mathematical model of SCR (selective catalytic reduction) system was established. On the basis of the verified feasibility, by CFD numerical analytical method, the reducing agent inside the catalysts concentration distribution was compared under different added urea schemes. Jet direction and the form of fuel injector were studied on the basis of the effects of reducing agent concentration distribution. The simulation result shows good agreement with the experimental data. The simulated results can be utilized in optimization design of the diesel SCR catalyst.

Development of the New NOx Reduction Catalyst With Hydrocarbons and the Cleanup Systems of Exhaust Gases for Lean-Burn Gas Engines

1999 ◽  
Author(s):  
Yukimaro Murata ◽  
Shigeo Satokawa ◽  
Ken-ichi Yamaseki ◽  
Hiromichi Yamamoto ◽  
Hiroshi Uchida ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nox Reduction ◽  
Reducing Agent ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Scr Catalyst ◽  
Exhaust Gases ◽  
Scr System ◽  
Three Way Catalyst ◽  
Al2o3 Catalyst

Abstract Development of cleanup technology for combustion waste is more and more necessary today. The emissions of stationary natural-gas-fueled engines can be purified by in-engine methods and by treatment of the exhaust gases. This paper describes the latter technologies. There are two conventional technologies for nitrogen oxides (NOx) reduction methods by the three-way catalyst and the selective catalytic reduction (SCR). The three-way catalyst operates only well within a narrow air-to-fuel ratio window, but when the exhaust gas is too lean, the NOx will not be removed. The SCR of NOx in exhaust gas has the advantage that the engine process itself does not have to be adapted and closely controlled as in case of extended lean-burn technologies. Ammonia or urea injected into the exhaust gas must be used as the reducing agent with conventional SCR system. However, the addition of a SCR system for the small or middle size cogeneration system, it would pose problems regarding cost and space for storage and injection of the reducing agent. Therefore, we have examining the catalyst which is able to reduce NOx with hydrocarbons (HC) containing in exhaust gas itself, and we developed the new HC-SCR catalyst. The de-NOx system using the HC-SCR catalyst has numerous advantages as follows: 1) Compactness and low cost: catalyst unit only 2) High efficiency: adaptation of lean-burn technology for engine operation 3) High performance: excellent catalytic activity and durability 4) Safeties: no use of ammonia as a reducing agent In this study, we report the catalytic activity of the new catalyst and propose a total cleanup system for exhaust gases of lean-burn gas engines. Alumina-supported silver (Ag/Al2O3) was used for the new catalyst. When the measurement was carried out with one reducing gas in the reactant gas each, propane and propane were most effective for NOx reduction, ethane and ethylene were secondly effective for NOx reduction. Practical test of the Ag/Al2O3 catalyst was carried out using a real exhaust gas from a 400 kW class lean-bum gas engine. The full-size catalyst was obtained by washcoating the catalyst powder on a metallic monolithic honeycomb substrate (size: 650 mm ϕ × 324 mmL, 200 cells/inch2). When the engine was operated at 400 kWe output, temperature of the exhaust gas was 762 K and GHSV was 17635 h−1. The NOx conversion was reached to 30% and the catalytic activity was maintained after the operation for more than 2000 hr. Conventional alumina-supported platinum (Pt/Al2O3) catalysts were mounted to exhaust gas line for cleanup test. The emission of CO and aldehydes was in the exhaust gas, but it could be highly removed by the Pt/Al2O3 catalyst. Practical tests of this catalyst were carried out using 300–400 kW class lean-burn gas engines. GHSV of these catalysts were about 50,000 h−1. The CO and aldehydes conversion were reached to more than 90% and the catalytic activities were maintained after the operation for about 10,000 hr.

Catalytic Control of NOx, CO, and NMHC Emissions From Stationary Diesel and Dual-Fuel Engines

1992 ◽  
Vol 114 (3) ◽  
pp. 597-601 ◽  
Author(s):  
R. W. Bittner ◽  
F. W. Aboujaoude
Keyword(s):  
Catalyst Surface ◽  
Catalytic Reduction ◽  
Catalyst System ◽  
Oxidation Catalyst ◽  
Dual Fuel ◽  
Catalyst Structure ◽  
Scr Catalyst ◽  
Heavy Hydrocarbons ◽  
Dual Fuel Engines ◽  
Scr System

Selective Catalytic Reduction (SCR) and oxidation catalyst technology have been applied to a stationary diesel and dual-fuel (natural gas and #2 diesel) engine for catalytic control of nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions. At rated conditions, NOx emissions have been effectively reduced by up to 90 percent, with little loss of SCR catalyst performance after 850 hours of operation. Using adequate control of the ammonia (NH3) feed, the SCR system was capable of maintaining NH3 slip to 10 ppm or less. CO and NMHC were reduced by 93 and 85 percent, respectively. Little soot was observed on the surface of the catalyst due to the use of a catalyst system that minimizes the buildup of heavy hydrocarbons on the catalyst surface. In addition, the catalyst structure effectively resisted the buildup of sulfur compounds that could cause premature deactivation of the catalyst.

scholarly journals Hybrid Technology for DeNOxing by LNT-SCR System for Efficient Diesel Emission Control: Influence of Operation Parameters in H2O + CO2 Atmosphere

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
Marina Cortés-Reyes ◽  
Concepción Herrera ◽  
María Ángeles Larrubia ◽  
Luis J. Alemany
Keyword(s):  
Catalytic Reduction ◽  
Scale Up ◽  
Lean Nox Trap ◽  
Scr Catalyst ◽  
Temperature Range ◽  
Small Pore ◽  
Lean Nox ◽  
Operation Parameters ◽  
The Rich ◽  
Scr System

The behavior and operation parameters were analyzed for the hybrid LNT-SCR (Lean NOx-Trap–Selective Catalytic Reduction) system with advanced catalyst formulations. Pt-Ba-K/Al2O3 was used as an NSR (NOx Storage and Reduction) or LNT catalyst effective in NOx and soot simultaneous removal whereas Cu-SAPO-34 with 2 wt.% of copper inside the structure was the small pore zeolite employed as the SCR catalyst. Under alternating and cyclic wet conditions, feeding volumetric concentrations of 1000 ppm of NO, 3% of O2, 1.5% of water, 0.3% of CO2, and H2 as a reductant, the NOx-conversion values were above 95% and a complete mineralization to nitrogen was registered using θ ≤ 3 (20 s of regeneration) and a hydrogen content between 10,000 and 2000 ppm in the whole temperature range tested. An excess of hydrogen fed (above 1% v/v) during the rich phase is unnecessary. In addition, in the low temperature range below 250 °C, the effect is more noticeable due to the further ammonia production and its possible slip. These results open the way to the scale up of the coupled catalytic technologies for its use in real conditions while controlling the influence of the operation map.

Get the Most Out of Your Gas Turbine SCR NOx Abatement System

2003 ◽  
Author(s):  
Martin F. Collins ◽  
S. Mario DeCorso ◽  
David L. Moen
Keyword(s):  
Catalytic System ◽  
System Performance ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Equipment Operation ◽  
Scr System ◽  
Scr Of Nox ◽  
Design Construction ◽  
Turbine Exhaust

Selective catalytic reduction (SCR) of NOx from turbine exhaust has been used successfully for at least 12 years. With this process, ammonia (NH3) is mixed with the exhaust gas before it passes through the SCR catalyst where the ammonia reacts selectively with the NOx, producing nitrogen and water. To make this simple reaction work properly over the life of the plant requires attention to issues during design and fabrication of the equipment, operation of the system, and quality control. There are a total of more than 25 issues involved. When all of these issues are recognized and addressed properly, the SCR catalytic system will produce the specified performance for the planned life of the catalyst. This paper identifies, describes, and discusses each of these issues. Most cases of unsatisfactory SCR turbine system performance can be traced to one or more of these issues being overlooked or not addressed properly in the design, construction, or operation of the catalytic system. The purpose of this paper is to make turbine system users aware of what must be done to get the most out of their SCR system.

Modeling of Urea-Water Solution Injection Spray in SCR System

2012 ◽  
Vol 232 ◽  
pp. 583-587
Author(s):  
Nayak S. Nagaraj ◽  
N. Kapilan ◽  
Prabhu S. Sadashiva
Keyword(s):  
Catalytic Reduction ◽  
Water Solution ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Exhaust Gas Aftertreatment ◽  
Study Results ◽  
Exhaust Stream ◽  
Experimental Values ◽  
Scr System ◽  
Aftertreatment Systems

To control the emissions from the diesel engines of modern automobiles, it requires the development of adequate and advanced exhaust gas aftertreatment devices. Selective Catalytic Reduction (SCR) is a method that can be used in mobile diesel engine aftertreatment systems to reduce harmful NOx emissions. Due to the toxicity and handling problems of ammonia, currently injection of a liquid Urea-Water Solution (UWS) into the exhaust stream approach is used. The water evaporates and the urea undergoes thermal decomposition producing ammonia that reacts with the NOx in the exhaust gas inside a SCR catalyst to produce nitrogen and water vapor. This work presents the study of UWS injection spray using commercial available CFD code, Fire v8.3. The evaporation of water from a single droplet of UWS is investigated theoretically and droplets are treated with Lagrangian particle tracking. Simulation study at different exhaust gas temperatures and injector locations is carried out and compared with experimental values. Thus, the present study results predict the local distribution and the conversion of the reducing agent.

Research of Microwave - Ethanol Auxiliary V2O5-WO3/TiO2 SCR Catalyst Regeneration Experiment

2014 ◽  
Vol 1015 ◽  
pp. 619-622
Author(s):  
Zhuang Kun Wang
Keyword(s):  
Catalytic Reduction ◽  
Physical Structure ◽  
Catalyst Regeneration ◽  
Practical Significance ◽  
Regeneration Process ◽  
Recovery Method ◽  
Scr Catalyst ◽  
Scr Catalysts ◽  
Element Enrichment ◽  
Scr System

Using selective catalytic reduction (SCR) that takes NH3 as the reducing agent to remove NOx is one of the most often used coal-fired flue gas denitration technology that of the highest denitration efficiency. As the core of the SCR system, catalyst is the important factors that affect the whole SCR system denitration efficiency. As the growth of the running time, catalyst tends to lose active energy because of the surface channel jam and toxic element enrichment and deactivation. Each year the deactivation catalyst regeneration process, can save a lot of money, thus help to avoid pollution of the environment. So study of the SCR catalyst regeneration technology is around the corner, which is of great practical significance for lowering the cost of the SCR system, promoting the application of the SCR technology, and protecting the environment. In this paper, the research takes vanadium series SCR catalysts as the object to study the regeneration technology of catalyst, new physical structure recovery method, and effect of regeneration process in the treatment on the performance of catalyst.

Thermal performance comparison of different sun tracking configurations

2019 ◽  
Vol 88 (2) ◽  
pp. 20902
Author(s):  
O. Achkari ◽  
A. El Fadar
Keyword(s):  
Thermal Performance ◽  
Electricity Generation ◽  
Arid Regions ◽  
Performance Comparison ◽  
Water Desalination ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
The Impact ◽  
The Mathematical Model ◽  
Good Agreement

Parabolic trough collector (PTC) is one of the most widespread solar concentration technologies and represents the biggest share of the CSP market; it is currently used in various applications, such as electricity generation, heat production for industrial processes, water desalination in arid regions and industrial cooling. The current paper provides a synopsis of the commonly used sun trackers and investigates the impact of various sun tracking modes on thermal performance of a parabolic trough collector. Two sun-tracking configurations, full automatic and semi-automatic, and a stationary one have numerically been investigated. The simulation results have shown that, under the system conditions (design, operating and weather), the PTC's performance depends strongly on the kind of sun tracking technique and on how this technique is exploited. Furthermore, the current study has proven that there are some optimal semi-automatic configurations that are more efficient than one-axis sun tracking systems. The comparison of the mathematical model used in this paper with the thermal profile of some experimental data available in the literature has shown a good agreement with a remarkably low relative error (2.93%).

TWC-SCR Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in HCCI, SACI, and SI Combustion Modes

2016 ◽  
Author(s):  
Jordan Easter ◽  
Stanislav V. Bohac
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Scr Catalyst ◽  
Advanced Combustion ◽  
Nox Conversion ◽  
Combustion Modes ◽  
Scr System ◽  
Nox Conversion Efficiency

Low temperature and dilute Homogenous Charge Compression Ignition (HCCI) and Spark Assisted Compression Ignition (SACI) can improve fuel economy and reduce engine-out NOx emissions to very low values, often less than 30 ppm. However, these combustion modes are unable to achieve stringent future regulations such as SULEV 30 without the use of lean aftertreatment. Though active selective catalytic reduction (SCR) with urea injection and lean NOx traps (LNT) have been investigated as options for lean gasoline engines, a passive TWC-SCR system is investigated in this work because it avoids the urea storage and dosing hardware of a urea SCR system, and the high precious metal cost of an LNT. The TWC-SCR concept uses periodic rich operation to produce NH3 over a TWC to be stored on an SCR catalyst for subsequent NOx conversion during lean operation. In this work a laboratory study was performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation, or between lean and rich SI (spark ignited) combustion, to evaluate NOx conversion and reduced fuel consumption. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system simulations are also presented that compare system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation showed a maximum NOx conversion efficiency of 10%, while lean/rich SI operation showed a maximum NOx conversion efficiency of 60%. However, if the low conversion efficiency of lean/rich HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, simulation results indicate TWC-SCR aftertreatment has the potential to provide near-zero SCR-out NOx concentration and increased system fuel efficiency. In these simulations, fuel efficiency improvement relative to stoichiometric SI were 7 to15% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although previous work indicated increased time for NH3 to start forming over the TWC during rich operation, less NH3 production over the TWC per fuel amount, and increased NH3 slip over the SCR catalyst for advanced combustion systems, if NOx conversion efficiency could be enhanced, improvements in fuel economy and low engine-out NOx from advanced combustion modes would more than make up for these disadvantages.

Optimization Research on Dynamic Balance of Spatial Engine under Limiting Shaking Moment

2009 ◽  
Vol 626-627 ◽  
pp. 693-698
Author(s):  
Yong Yong Zhu ◽  
S.Y. Gao
Keyword(s):  
Mathematical Model ◽  
Objective Function ◽  
Kinetic Analysis ◽  
Optimization Design ◽  
Design Method ◽  
Dynamic Balance ◽  
Optimized Design ◽  
Design Variables ◽  
The Mathematical Model ◽  
Shaking Moment

Dynamic balance of the spatial engine is researched. By considering the special wobble-plate engine as the model of spatial RRSSC linkages, design variables on the engine structure are confirmed based on the configuration characters and kinetic analysis of wobble-plate engine. In order to control the vibration of the engine frame and to decrease noise caused by the spatial engine, objective function is choosed as the dimensionless combinations of the various shaking forces and moments, the restriction condition of which presents limiting the percent of shaking moment. Then the optimization design is investigated by the mathematical model for dynamic balance. By use of the optimization design method to a type of wobble-plate engine, the optimization process as an example is demonstrated, it shows that the optimized design method benefits to control vibration and noise on the engines and improve the performance practically and theoretically.

Sign in / Sign up

Export Citation Format

Share Document