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.

A Simplified One-Dimensional Mathematical Model to Study the Transient Thermal Behavior of an Oxidation Catalyst with Both Low and High Levels of CO Concentration at the Inlet

2019 ◽  
Vol 14 (3) ◽  
Author(s):  
Priyabrata Mohapatra ◽  
Mayank Mittal
Keyword(s):  
Thermal Behavior ◽  
Co Oxidation ◽  
Heat Generation ◽  
Catalyst System ◽  
Oxidation Catalyst ◽  
Dual Fuel ◽  
Engine Exhaust ◽  
Warm Up ◽  
Co Concentration ◽  
Transient Thermal

Abstract In recent years, the permissible limits of engine exhaust emissions are reduced considerably. Hence a quick warm-up and high conversion efficiency of the catalyst system is essential to meet upcoming stringent emission regulations. In the present work, the transient thermal behavior of an oxidation catalyst is studied using a one-dimension mathematical modeling approach with the focus on CO oxidation for dual-fuel engine application. At first, the heat generation due to chemical reactions is considered negligible for studying the warm-up behavior. Upon obtaining a good agreement between predicted warm-up temperature profiles with available literature data, the effect of an electrical heater on the warm-up behavior is investigated. The model is then extended by incorporating heat generation due to CO oxidation. A simplified reaction rate model is considered in order to reduce the computational complexity. It is observed that the simplified model agrees well with the experimental data for both low and high levels of CO concentration at the inlet, typical in dual-fuel technology when an engine is operated under diesel and dual-fuel modes, respectively.

scholarly journals Deactivation of a Vanadium-Based SCR Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 552
Author(s):  
Johanna Englund ◽  
Sandra Dahlin ◽  
Andreas Schaefer ◽  
Kunpeng Xie ◽  
Lennart Andersson ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Heavy Duty ◽  
Scr Catalyst ◽  
Before And After ◽  
Emission Control System ◽  
Catalyst Poisons

We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons from the combustion was investigated for the up-stream particulate filter as well as the SCR catalyst. The NOx reduction performance in terms of standard, fast and NO2-rich SCR was evaluated before and after exposure to exhaust from a biogas-powered engine for 900 h. The SCR catalyst retains a significant part of its activity towards NOx reduction after exposure to biogas exhaust, likely due to capture of catalyst poisons on the up-stream components where the deactivation of the oxidation catalyst is especially profound. At lower temperatures some deactivation of the first part of the SCR catalyst was observed which could be explained by a considerably higher surface V4+/V5+ ratio for this sample compared to the other samples. The higher value indicates that the reoxidation of V4+ to V5+ is partially hindered, blocking the redox cycle for parts of the active sites.

Simulation and Optimization of Urea-SCR System in Diesel Engine

2013 ◽  
Vol 316-317 ◽  
pp. 1156-1161 ◽  
Author(s):  
Qian Wang ◽  
Duo Zhang ◽  
Jing Wang ◽  
Shuo Li
Keyword(s):  
Chemical Reaction ◽  
Catalytic Converter ◽  
Three Dimensional ◽  
Catalyst System ◽  
Spray Angle ◽  
Urea Solution ◽  
Scr Catalyst ◽  
Simulation And Optimization ◽  
Scr System ◽  
Reaction Characteristic

A three-dimensional Urea-SCR catalytic converter model was simulated with the method of CFD coupled with chemical reaction dynamic in this paper. With the modeling of urea solution injection and spray, the urea spray angle was optimized to reduce the urea wallfilm on the pipe wall. The flow fields and component distributions of a full scale Urea-SCR catalyst system were obtained to analyze the flow and chemical reaction characteristic of SCR system. Finally, an SCR system with a simple blade SCR mixer was simulated, the results indicated that the mixer can accelerate the evaporation and thermolysis of urea solution, and improve reductant uniformity and NOx conversion efficiency of Urea-SCR system.

Field Experience and Laboratory Analysis of Oxidation Catalyst on Dual Fuel Engines

2006 ◽  
Author(s):  
Shazam Williams ◽  
Mojghan Naseri ◽  
Joe Aleixo ◽  
Kristoffer Sandelin
Keyword(s):  
Continuous Operation ◽  
Fuel Oil ◽  
Oxidation Catalyst ◽  
Laboratory Evaluation ◽  
Dual Fuel ◽  
Heavy Fuel Oil ◽  
Gas Cleaning ◽  
Exhaust Gas Cleaning ◽  
Dual Fuel Engines ◽  
Engine Maintenance

A DCL oxidation catalyst for exhaust-gas cleaning has been field tested on a Wa¨rtsila¨ 50 series dual-fuel engine during 5000 hours of continuous operation in an end-user power plant application. The engine has been designed for continuous operation on natural gas (NG), light fuel oil (LFO) as well as heavy fuel oil (HFO), thus giving the consumer a wide variety of fuelling options. All three fuels were used at some point during the 5000 hours field trial. These fuels have different properties such as differing levels of sulphur and ash contents that affect the abatement efficiencies of the oxidation catalyst. A detailed study was performed to understand the effect of different fuels, lube oil poisoning and long running hours on the abatement performance of the oxidation catalyst. The oxidation catalyst was equipped with sample cores that were exchanged during scheduled engine maintenance periods. This allowed parallel field and laboratory evaluation of the emissions abatement and the quantity of lube oil deposits on the catalyst at successive intervals of engine running hours. We will show that the combination of the dual fuel engine and the oxidation catalyst is very robust, even for the different fuels, and it gives low emissions.

Modeling and Simulation of Selective Catalytic Reduction for Flue Gas Denitration in Power Plants

2011 ◽  
Vol 383-390 ◽  
pp. 6580-6586
Author(s):  
Bo Xiong Shen ◽  
Ning Zhao ◽  
Ting Liu ◽  
Feng Peng Wu ◽  
Chen Zuo
Keyword(s):  
Selective Catalytic Reduction ◽  
Power Plants ◽  
Ammonia Oxidation ◽  
Catalytic Reduction ◽  
Kinetic Mechanism ◽  
Reduction Reaction ◽  
Catalyst Structure ◽  
Scr Catalyst ◽  
Selective Catalytic Reduction Reaction ◽  
Catalyst Type

Based on Eley-Rideal kinetic mechanism, one dimensional mathematical model for selective catalytic reduction reaction was established, in order to simulate the SCR process in the catalyst channel. The thermal effect on the reaction and the side effect of ammonia oxidation in the channel were considered simultaneously in the modeling. The model was testified to be reliable by compared with the experimental data. By the model, the concentration and temperature distributions in the channel were simulated. The effects of catalyst structure parameters, such as the pitch, the shape of catalyst channel and the monolithic catalyst type, on de-NOX efficiency were studied emphatically. The simulation results would be as an important reference for the design of SCR catalyst in the practical application.

NO2 Reaction Pathways With NH3 on an Fe-Zeolite SCR Catalyst

2011 ◽  
Author(s):  
Michael A. Smith ◽  
Christopher D. Depcik ◽  
Stefan Klinkert ◽  
John W. Hoard ◽  
Stanislav V. Bohac ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Catalyst System ◽  
Lean Nox Trap ◽  
Scr Catalyst ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Lean Nox ◽  
System Part

One approach for nitrogen oxides (NOx) emission control of medium duty diesel engines is through the use of a combination Lean NOx Trap and Selective Catalytic Reduction (LNT-SCR) catalyst system. In this system, part of the NOx conversion occurs via an NH3 SCR catalyst that is dependent on the NO2 to NOx ratio of the feed gas with NO2 being a more advantageous oxidizer. One benefit of using this system is the conversion of NO to NO2 over the LNT which increases the NO2:NOx ratio of the feed gas to the SCR catalyst. An experimental study has been performed to investigate the NO2-NH3 reaction for an Fe-based zeolite SCR catalyst using a bench top flow reactor. The increase in NO2 concentration at the inlet of the SCR results in the formation of large quantities of N2O from 200°C to 400°C. Further experiments determined that N2O and NH3 react above 350°C. This has led to a hypothesis that one primary SCR reaction (Slow SCR) can be replaced with two reaction steps featuring NH3, NO2, and N2O. As a result, this paper proposes five NOx reduction reactions as part of a global mechanism, which would account for the observed experimental behavior.

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.

Observer-Based Estimation of Diesel Engine Aftertreatment System NO and NO2 Concentrations

2010 ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Catalytic Reduction ◽  
Diesel Oxidation Catalyst ◽  
Observer Design ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
System Control ◽  
Aftertreatment System ◽  
Current Production ◽  
Scr System

This paper presents an observer design for Diesel engine aftertreatment system NO and NO2 concentrations estimations. NO and NO2 have different reaction characteristics within SCR systems. Current production NOx sensors cannot differentiate NO and NO2. Such an observer thus can be used by selective catalytic reduction (SCR) system control and diagnosis purposes. Diesel oxidation catalyst (DOC) and Diesel particulate filter (DPF) were considered as the catalysts which can affect NO/NO2 fraction of the exhaust gas upstream of the SCR. The observer was designed based on an experimentally-validated control-oriented dynamic model which can accurately represent the NO and NO2 dynamics from engine-out, through DOC, and to DPF. Stability of the observer was theoretically proved through a Lyapunov analysis assisted by insight into the system characteristics. The effectiveness of the observer was shown by comparing the estimated NO and NO2 concentrations with the measured ones by a Horiba emissions measurement system.

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