scholarly journals Numerical Simulations of SCR DeNOx System for a 660MW coal-fired power station

2018 ◽  
Vol 38 ◽  
pp. 04009
Author(s):  
Deng Yongqiang ◽  
Mei Zhongming ◽  
Mao Yijun ◽  
Liu Nianping ◽  
Yin Guoming
Keyword(s):  
Numerical Simulations ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Structural Parameters ◽  
Escape Rate ◽  
Power Station ◽  
Factors Affecting ◽  
Operational Conditions ◽  
High Ammonia ◽  
Scr System

Aimed at the selective catalytic reduction (SCR) DeNOx system of a 660 MW coal-fired power station, which is limited by low denitrification efficiency, large ammonia consumption and over-high ammonia escape rate, numerical simulations were conducted by employing STAR-CCM+ (CFD tool). The simulations results revealed the problems existed in the SCR DeNOx system. Aimed at limitations of the target SCR DeNOx system, factors affecting the denitrification performance of SCR, including the structural parameters and ammonia injected by the ammonia nozzles, were optimized. Under the optimized operational conditions, the denitrification efficiency of the SCR system was enhanced, while the ammonia escape rate was reduced below 3ppm. This study serves as references for optimization and modification of SCR systems.

Perspective on SCR NOx control for diesel vehicles

2019 ◽  
Vol 4 (6) ◽  
pp. 969-974 ◽  
Author(s):  
Christine K. Lambert
Keyword(s):  
Steady State ◽  
Selective Catalytic Reduction ◽  
Research Design ◽  
Catalytic Reduction ◽  
System Research ◽  
Reduction Of No ◽  
Diesel Vehicles ◽  
Aqueous Urea ◽  
Nox Control ◽  
Scr System

The selective catalytic reduction of NOx with aqueous urea (“urea SCR”) is originally a steady-state technology that has been successfully applied to diesel vehicles worldwide. This Perspective summarizes 20+ years of SCR system research, design, and future improvements.

Modelling and parametric investigation of NOx reduction by oxidation precatalyst-assisted ammonia-selective catalytic reduction

2009 ◽  
Vol 223 (9) ◽  
pp. 1193-1206 ◽  
Author(s):  
S-C Jung ◽  
W-S Yoon
Keyword(s):  
Selective Catalytic Reduction ◽  
Low Temperatures ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Volume Ratio ◽  
Kinetic Scheme ◽  
Space Velocity ◽  
Gas Temperature ◽  
Scr System ◽  
Very High

Nitrogen oxide (NO x) reduction by the selective catalytic reduction (SCR) system assisted by an oxidation precatalyst is modelled and analytically investigated. The Langmuir—Hinshelwood SCR kinetic scheme with vanadium-based catalyst and ammonia (NH3) reductant in conjunction with the NO—NO2 conversion reaction over a platinum-based catalyst is used. The effects of the ratio of the oxidation precatalyst to the SCR monolith volume, the gas temperature, the space velocity, and the NH3-to-NO x concentration ratio on the de-NO x performance are parametrically examined. The oxidation precatalyst promotes NO x conversion at low temperatures. At intermediate temperatures, the NO x reduction is either activated or deactivated with increase in the space velocity. A higher oxidation precatalyst-to-SCR monolith volume ratio tends to promote the NO x reduction of higher space velocities. At high temperatures, the de-NO x efficiency is very high and insensitive to the space velocity. The NO x conversion efficiency depends on the NH3-to-NO x ratio at low temperatures.

Factors Affecting Mercury Oxidation by SCR Catalysts

2014 ◽  
Vol 986-987 ◽  
pp. 755-760
Author(s):  
Wen Du ◽  
Li Bao Yin ◽  
Yu Qun Zhuo ◽  
Qi Sheng Xu ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Injection Rate ◽  
Mercury Oxidation ◽  
Factors Affecting ◽  
Scr Catalysts ◽  
Negative Effect ◽  
Oxidation Efficiency ◽  
Scr System

The application of selective catalytic reduction (SCR) system may affect mercury speciation in coal-combustion flue gas. The factors affecting mercury oxidation efficiency by SCR catalysts have been evaluated in this research. The influencing factors investigated included hydrogen chloride (HCl), sulfur dioxide (SO2), ammonia (NH3) injection rate and space velocity. HCl had been found to promote mercury oxidation significantly. The Eley-Rideal mechanism was proven to be suitable to explain the reaction of Hg0 and HCl. NH3 injection had a strong negative effect to mercury oxidation. The deactivation of aged SCR catalysts was mainly due to loss of active sites.

Isothermal Physical Flow Modeling of a Gas Turbine Simple-Cycle Selective-Catalytic-Reduction (SCR) System

2013 ◽  
Author(s):  
Larry Swanson ◽  
Hua Zhang ◽  
Doug Byrd
Keyword(s):  
Selective Catalytic Reduction ◽  
Gas Turbine ◽  
Catalytic Reduction ◽  
Transport Processes ◽  
Simple Cycle ◽  
Minor Effect ◽  
Tracer Injection ◽  
A Minor ◽  
Scr System ◽  
The Impact

A physical flow model of a gas turbine (GT) simple-cycle Selective-Catalytic-Reduction (SCR) system was constructed to a 1/16 geometric scale to validate computational fluid dynamics (CFD) predictions and examine the impact of tempering air injection on system performance. Repeatable velocity contours and tempering air dispersion profiles were developed for baseline (no tempering air), and 12- and 6-lance tempering air injector configurations. The conclusions from the study are: (1) relative to the no lance baseline case, the 12-lance configuration tends to force more of the inlet flow towards the top of the duct, whereas the 6-lance configuration does not affect the upstream profile significantly, (2) adding tempering air does not have a significant impact on the diffuser inlet velocity distribution and has a minor effect on the velocity and dispersion profiles at the NOX-catalyst inlet, (3) at the NOX-catalyst inlet, the 6-lance configuration with tempering air exhibits a slightly skewed flow toward the lower right corner of the duct with a coefficient of variation (COV) of 19.4%, which is slightly better than that for the 12-lance configuration, (4) at the NOX-catalyst inlet, the 12-lance configuration disperses tempering air best because its COV is 20.8% relative to a 27.3% COV for the 6-lance configuration, and (5) a comparison between the local mixing-cup temperature contours for both 12- and 6-lance configurations, based on tracer injection into the tempering air flow, confirms that the CFD model does a good job of qualitatively predicting the heat and mass transport processes in the GT simple-cycle SCR system.

Flow Modeling for a Simple Cycle Turbine Equipped With Selective Catalytic Reduction System for NOx Control

2005 ◽  
Author(s):  
Khoa Nguyen ◽  
Dani Fadda ◽  
Mark Buzanowski
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Velocity Profiles ◽  
Design Flow ◽  
Simple Cycle ◽  
Cfd Modeling ◽  
Compact Design ◽  
Calculated Velocity ◽  
Scr System ◽  
Flow Devices

A selective catalytic reduction (SCR) system, when designed for a simple cycle turbine, presents a significant calculation and modeling challenge due to its compact design and stringent performance requirements. In particular, uniform flue gas velocity profiles, required by environmental catalysts installed in the ductwork of this system, must be met. Custom flow devices optimized for the turbine. SCR system and ductwork are required. Cold flow and computational fluid dynamics (CFD) modeling are employed to design flow devices that provide adequate velocity profiles. The purpose of this paper is to present (1) steps taken to optimize the ductwork internals and (2) measured and calculated velocity profiles.

Lubrication regime analysis for spherical pump

2018 ◽  
Vol 70 (8) ◽  
pp. 1437-1446 ◽  
Author(s):  
Dong Guan ◽  
Harry H. Hilton ◽  
Zhengwei Yang ◽  
Li Jing ◽  
Kuan Lu
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Structural Parameters ◽  
Equivalent Model ◽  
Radial Clearance ◽  
Content Type ◽  
Factors Affecting ◽  
Operational Conditions ◽  
Intellectual Content ◽  
Lubrication Regime

Purpose This paper aims to investigate the lubrication regime in spherical pump, especially under different structural parameters and operational conditions. Design/methodology/approach A ball-on-plane configuration is adopted to represent the contact model between spherical piston and cylinder cover. The governing equations, which include the Reynolds and elasticity equations, are solved and validated by Jin–Dowson model. Both minimum film thickness and lambda ratio (ratio of minimum fluid film thickness to combined surface roughness of the piston and cylinder cover) of the equivalent model are obtained using an established model. Findings The results indicate that piston diameter and radial clearance are the two main factors affecting the pump lubrication regime. Other related parameters such as rotation speed of the piston, load, viscosity of working medium, material matching and surface roughness of piston and cylinder cover also have different impacts on the lubrication regime of the spherical pump. Originality/value These results emphasize the importance of the design and manufacturing parameters on the tribological performance of spherical pumps and these are also helpful in improving the spherical pump lubrication regime and enlarging its life cycle. This is to certify that to the best of the authors’ knowledge, the content of this manuscript is their own work. This manuscript has only been submitted to this journal and never been published elsewhere. The authors certify that the intellectual content of this manuscript is the product of their own work and that all the assistance received in preparing this manuscript and sources has been acknowledged.

Observer-Based Estimation of Aging Condition for Selective Catalytic Reduction Systems in Vehicle Applications

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yao Ma ◽  
Junmin Wang
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Estimation Error ◽  
Nox Reduction ◽  
Observer Design ◽  
Accurate Estimation ◽  
Nox Emissions ◽  
Aging Condition ◽  
Entire Vehicle ◽  
Scr System

This paper presents two observers for estimating the aging condition of selective catalytic reduction (SCR) systems in vehicle applications. SCR systems have been widely recognized as one of the leading engine exhaust gas aftertreatment systems for reducing diesel powertrain tailpipe NOx emissions in ground vehicle applications. While fresh SCRs are quite effective in reducing tailpipe NOx emissions, their NOx reduction capabilities and performances may substantially degrade with in-service aging. To maintain the emission control performance of a SCR system for a diesel engine during the entire vehicle service life, it is thus critical to have an accurate estimation of the SCR system aging condition. In this paper, two Lyapunov-based observers utilizing the measurements of NOx and ammonia concentrations are analytically developed and verified in simulations for estimating the SCR aging condition. The measurement uncertainty is explicitly considered in the observer design process. A sufficient condition for the boundedness of the estimation error is derived. Simulation results under the US06 test cycle demonstrate the effectiveness of the proposed observers.

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