scholarly journals Reaction Pathways and Kinetics for Selective Catalytic Reduction (SCR) of Acidic NOx Emissions from Power Plants with NH3

ACS Catalysis ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 8358-8361 ◽  
Author(s):  
Minghui Zhu ◽  
Jun-Kun Lai ◽  
Uma Tumuluri ◽  
Michael E. Ford ◽  
Zili Wu ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Reaction Pathways ◽  
Nox Emissions

Improvement of Selective Catalytic Reduction System Performance in Combined Cycle Power Plants

2003 ◽  
Author(s):  
Anatoly Sobolevskiy ◽  
Tom Czapleski ◽  
Richard Murray
Keyword(s):  
Selective Catalytic Reduction ◽  
Mass Flow ◽  
System Performance ◽  
Gas Turbines ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Active Material ◽  
Combined Cycle ◽  
Nox Emissions ◽  
Scr System

Environmental regulations are very stringent in the U.S., requiring very low emissions of nitrogen oxides (NOx) from combined cycle power plants. Selective Catalytic Reduction (SCR) systems utilizing vanadium pentoxide (V2O5) as the active material in the catalyst are a proven method of reducing NOx emissions in the exhaust stack of gas turbines with heat recovery steam generators (HRSG) to 2–4 ppmvd. These low NOx emissions levels require an increase of SCR removal efficiency to the level of 90+ % with limited ammonia slip. The distribution of flow velocities, temperature, and NOx mass flow at the inlet of the SCR are critical to minimizing NOx and ammonia (NH3) concentrations in HRSG stack. The short distance between the ammonia injection grid and the catalyst in the HRSG complicates the achievement of homogeneous NH3 and NOx mixture. To better understand the influence of the above factors on overall SCR system performance, field testing of combined cycle power plants with an SCR installed in the HRSG has been conducted. Uniformity of exhaust flow, temperature and NOx emissions upstream and downstream of the SCR were examined and the results served as a basis for SCR system tuning in order to increase its efficiency. NOx mass flow profiles upstream and downstream of the SCR were used to assess ammonia distribution enhancement. Ammonia flow adjustments within a cross section of the exhaust gas duct yielded significantly improved NOx mass flow uniformity after the SCR while reducing ammonia consumption. Based on field experience, a procedure for ammonia distribution grid tuning was developed and recommendations for SCR performance improvement were generated.

Selective Catalytic Reduction of NOx Emissions

2021 ◽  
pp. 1115-1130
Author(s):  
R. J. G. Nuguid ◽  
F. Buttignol ◽  
A. Marberger ◽  
O. Kröcher
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Emissions ◽  
Reduction Of Nox

scholarly journals Current Catalyst Technology of Selective Catalytic Reduction (SCR) for NOx Removal in South Korea

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 52 ◽  
Author(s):  
Hyo-Sik Kim ◽  
Saravanan Kasipandi ◽  
Jihyeon Kim ◽  
Suk-Hwan Kang ◽  
Jin-Ho Kim ◽  
...  
Keyword(s):  
Air Pollution ◽  
Nitrogen Oxides ◽  
South Korea ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Research Trends ◽  
Nox Emissions ◽  
Nox Removal ◽  
National Characteristics ◽  
The World

Recently, air pollution has worsened throughout the world, and as regulations on nitrogen oxides (NOx) are gradually tightened many researchers and industrialists are seeking technologies to cope with them. In order to meet the stringent regulations, research is being actively conducted worldwide to reduce NOx-causing pollution. However, different countries tend to have different research trends because of their regional and industrial environments. In this paper, the results of recent catalyst studies on NOx removal by selective catalytic reduction are reviewed with the sources and regulations applied according to the national characteristics of South Korea. Specifically, we emphasized the three major NOx emissions sources in South Korea such as plant, automobile, and ship industries and the catalyst technologies used.

Coordinated Active Thermal Management and Selective Catalytic Reduction Control for Simultaneous Fuel Economy Improvement and Emissions Reduction During Low-Temperature Operations

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Pingen Chen ◽  
Junmin Wang
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Thermal Management ◽  
Catalytic Reduction ◽  
Coordinated Control ◽  
Nox Emissions ◽  
Total Cost ◽  
Nox Conversion ◽  
Ammonia Slip ◽  
Nox Conversion Efficiency

The low-temperature operations of diesel engines and aftertreatment systems have attracted increasing attention over the past decade due to the stringent diesel emission regulations and excessive tailpipe emissions at low temperatures. The removal of NOx emissions using selective catalytic reduction (SCR) systems during low-temperature operations remains a significant challenge. One of the popular techniques for alleviating this issue is to employ active thermal management via in-cylinder postinjection to promote aftertreatment system temperatures. Meanwhile, numerous studies have focused on ammonia coverage ratio controls with the aim to maintain high NOx conversion efficiency and low tailpipe ammonia slip. However, most of the active thermal management and SCR controls in the existing literatures were separately and conservatively designed, which can lead to higher cost of SCR operation than needed including diesel fuel consumption through active thermal management and urea solution consumption. The main purpose of this study is to design and coordinate active thermal management and SCR control using nonlinear model predictive control (NMPC) approach to minimize the total cost of SCR operation while obtaining high NOx conversion efficiency and low tailpipe ammonia slip. Simulation results demonstrate that, compared to the baseline control which consists of separated active thermal management and SCR control, the coordinated control is capable of reducing the total cost of SCR operation by 25.6% while maintaining the tailpipe NOx emissions and ammonia slip at comparable levels. Such an innovative coordinated control design concept shows its promise in achieving low tailpipe emissions during low-temperature operations in a cost-effective fashion.

Investigation of the System Coupling Regenerative Heat Exchange and Selective Catalytic Reduction for Heat Exchange and NOx Removal

2014 ◽  
Vol 955-959 ◽  
pp. 2087-2092
Author(s):  
Zhong Jun Tian ◽  
Shi Ping Jin ◽  
Yu Ming Liang
Keyword(s):  
Heat Exchange ◽  
Selective Catalytic Reduction ◽  
Power Plants ◽  
Switching Time ◽  
Catalytic Reduction ◽  
Coupled System ◽  
Experimental Investigations ◽  
Regenerative Heat ◽  
System Coupling ◽  
Peak Value

In conjunction with theoretical heat exchange model, experimental investigations have been conducted for a coupled system of Selective Catalytic Reduction (SCR) and Regenerative Heat Exchange (RHE), to reduce nitrogen oxides (NOx) from coal-fired boilers and High Temperature Air Combustion (HiTAC) furnaces. Results indicate there is no effect of catalysis reactions on heat transfer; catalysts serve the function of heating elements. The outlet NO concentration periodically decreased in an almost linear fashion. NO conversion: i) rose slowly with a longer switching time; and ii) reached the peak value of temperature with a delay compared with the steady state. The coupled system requires less space and hence is a suitable option for SCR renovations in coal-fired power plants.

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