Leveraging Physical and Computational Flow Modeling Techniques in the Optimization of Commercial Selective Catalytic Reduction System Designs

2002 ◽  
Author(s):  
David K. Anderson ◽  
Martin J. Kozlak
Keyword(s):  
Gas Flow ◽  
Catalytic Reduction ◽  
Flow Characteristics ◽  
Flow Models ◽  
Low Load ◽  
Modeling Techniques ◽  
Fluid Flow Characteristics ◽  
Scr System ◽  
System Designs ◽  
Ammonia Injection

To ensure optimal SCR system performance, physical and computational flow models of proposed SCR installations are used to guide the development of system components, such as the ammonia injection grid and various flow and thermal conditioning devices. Proper attention to these details is particularly important in retrofit applications where the ducts leading to the SCR reactor often cannot be designed for optimal fluid flow characteristics. This paper discusses the process of SCR modeling including the techniques employed to accurately model gas flow, NOx, ammonia, and thermal distributions and mixing. Additionally, the development of economizer bypass systems for SCR temperature control during low-load operation is discussed.

Optimized Ammonia Injection for Power Plant SCR Systems

2007 ◽  
Author(s):  
Mark A. Buzanowski ◽  
Dani Fadda
Keyword(s):  
Catalytic Reduction ◽  
Nox Reduction ◽  
Experimental Studies ◽  
Life Time ◽  
Mixing Efficiency ◽  
Exhaust Gas ◽  
System Pressure ◽  
Mixing Distance ◽  
Scr System ◽  
Ammonia Injection

Ammonia injection grid (AIG) is used to introduce vaporized ammonia (NH3) into an exhaust gas stream for nitrous oxide (NOx) reduction in selective catalytic reduction (SCR) systems. Computational and experimental studies on the AIG resulted in significant improvements in the turbulence mixing between the injected ammonia and the exhaust gas. Improved mixing is instrumental to maximize catalyst performance, extend catalyst life time, minimize catalyst volume, decrease system pressure drop, minimize reagent use and ammonia slip, minimize the overall size of the SCR system, and minimize risks associated with designing the SCR system. It is found that an AIG with a turbulence-generating edge dramatically increases the mixing efficiency and, therefore, reduces the mixing distance required to obtain acceptable distributions of the NH3 to NOx ratio. Results indicate over 50% reduction of the required mixing distance due to the turbulence generating edge. This work summarizes the obtained results from computational CFD simulations for two-dimensional and three-dimensional models, however the proposed arrangement of the injection grid has been successfully tested in laboratory experiments and applied to several commercial power generating systems. The commercial performance results will be reported in the subsequent publications.

Emerging Challenges and Design Strategies for SCR Systems

2014 ◽  
Author(s):  
Larry Czarnecki ◽  
Paulo Oliveira
Keyword(s):  
High Performance ◽  
Catalytic Reduction ◽  
Direct Injection ◽  
Design Strategies ◽  
Traditional Design ◽  
Utility Boilers ◽  
Effective Technology ◽  
Injection Methods ◽  
Scr System ◽  
Ammonia Injection

Selective Catalytic Reduction has been well demonstrated as an effective technology for reducing NOx emissions from coal-fired utility boilers. Emerging environmental regulations can have an impact on the traditional design and operation of an SCR system. Increasing demands on SCR emission reduction performance affects the design of many of the SCR components aside from the catalyst bed. Obtaining an optimal distribution of ammonia reagent in the flue gas stream is a primary requirement for high performance levels. This requirement must be balanced with limited space availability, all while obtaining both robust operation and minimal operating costs. Addressing these issues has led to the development of a variety of ammonia injection and distribution methods. Gas mixer designs, such as the IsoSwirl™ mixer, offer a means to obtain high levels of NOx removal while addressing problematic conditions and featuring simple ammonia delivery systems. Ammonia injection methods may utilize either traditional, vapor-phase techniques or the direct injection of an aqueous ammonia supply which avoids ammonia vaporizer requirements.

scholarly journals Experimental research and CFD analysis of flow parameters in a SCR system for the original part and WALKER’s replacement

2019 ◽  
Vol 179 (4) ◽  
pp. 13-20
Author(s):  
Damian KURZYDYM ◽  
Adam KLIMANEK ◽  
Zbigniew ŻMUDKA
Keyword(s):  
Reverse Engineering ◽  
Experimental Research ◽  
Gas Flow ◽  
Catalytic Reduction ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
3D Geometry ◽  
Flow Through ◽  
Original Part ◽  
Scr System

The article presents the results of experimental research and their comparison with CFD simulations for the original selective catalytic reduction system and WALKER replacement. The research was performed to develop the WALKER universal mixer. The SCR prototype without mixer and with the proposed mixer were tested and compared with the original VW part. The next step was reverse engineering, which consisted in scanning the tested parts with a laser and processing their point cloud in Leios2 program. Reverse engineering has allowed the reconstruction of 3D geometry of the tested parts in the Catia v5 program and then preparation their models for computational fluid dynamics. Numerical simulations were carried out in the Ansys Fluent program, thanks to which several quantities were determined e.g. uniformity index of gas flow through the monolith and coefficient of variation as a measure of mixing degree, which have a significant impact on the design of the mixer and the SCR system.

scholarly journals Spraying and Mixing Characteristics of Urea in a Static Mixer Applied Marine SCR System

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5788
Author(s):  
Jaehwan Jang ◽  
Sangkyung Na ◽  
Heehwan Roh ◽  
Seongyool Ahn ◽  
Gyungmin Choi
Keyword(s):  
Degrees Of Freedom ◽  
Gas Flow ◽  
Catalytic Reduction ◽  
Water Solution ◽  
Urea Solution ◽  
Static Mixer ◽  
Manufacturing Companies ◽  
Conversion Reaction ◽  
Marine Diesel ◽  
Scr System

The most effective de-NOx technology in marine diesel applications is the urea-based selective catalytic reduction (SCR) system. The urea-SCR system works by injecting a urea solution into exhaust gas and converting this to NH3 and CO2. The injection, mixing, and NH3 conversion reaction behavior of the urea-water solution all have a decisive effect on the performance of the system. To improve de-NOx efficiency, it is important to provide enough time and distance for NH3 conversion and uniform distribution prior to the solution entering the catalyst. In this study, therefore, the characteristics of gas flow, NH3 conversion, and its distribution are investigated with a static mixer by means of numerical methods, providing a special advantage to ship manufacturing companies through the optimization of the urea-SCR system. The results show that the inclusion of the mixer induces strong turbulence and promotes the NH3 conversion reaction across a wider region compared to the case without the mixer. The mean temperature is 10 °C lower due to the activated endothermic urea-NH3 conversion reaction and the NH3 concentration is 80 PPM higher at 1D than those without the mixer. Moreover, the uniformity of NH3 distribution improved by 25% with the mixer, meaning that the de-NOx reaction can take place across all aspects of the catalyst thus maximizing performance. In other words, ship manufacturing companies have degrees of freedom in designing post-processing solutions for emissions by minimizing the use of the reduction agent or the size of the SCR system.

Heat Transfer and Fluid Flow Characteristics of Nonboiling Two-Phase Flow in Microchannels

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Kyosung Choo ◽  
Sung Jin Kim
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Diameter ◽  
Fluid Flow Characteristics

In this study, heat transfer and fluid flow characteristics of nonboiling two-phase flow in microchannels were experimentally investigated. The effects of channel diameter (140, 222, 334, and 506 μm) on the Nusselt number and the pressure drop were considered. Air and water were used as the test fluids. Results were presented for the Nusselt number and the pressure drop over a wide range of gas superficial velocity (1.24–40.1 m/s), liquid superficial velocity (0.57–2.13 m/s), and wall heat flux (0.34–0.95 MW/m2). The results showed that the Nusselt number increased with increasing gas flow rate for the large channels of 506 and 334 μm, while the Nusselt number decreased with increasing gas flow for the small channels of 222 and 140 μm. Based on these experimental results, a new correlation for the forced convection Nusselt number was developed. In addition, the two-phase friction multiplier is shown to decrease as channel diameter decreases due to the influence of viscous and surface tension forces.

Fluid Flow Characteristics in Micro-Gas-Jets

2014 ◽  
Author(s):  
Yutaka Asako
Keyword(s):  
Fluid Flow ◽  
Mach Number ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Gas Jet ◽  
Current Status ◽  
Potential Core ◽  
Numerical Studies ◽  
Displacement Thickness ◽  
Fluid Flow Characteristics

This paper reviews the current status of researches on a micro-gas-jet from a straight micro-tube. A series of experimental and numerical studies on a micro-gas-jet from a straight micro-tube have been conducted by our research group to reveal fluid flow characteristics of under-expanded gas flow at a micro-tube outlet. In this paper, the findings obtained by our recent studies will be introduced. This is, the numerically obtained Mach number at the outlet plane of a micro-tube, the displacement thickness of the boundary layer formed on the tube wall near the outlet are presented. The configuration of a micro-gas-jet and structure of the flow in the potential core are presented. And the Mach number of a micro-gas-jet obtained from the shockwave angle generated from a needle tip inserted in the micro-jet and the measured Pitot total pressure of a micro-gas-jet are also presented. Comparisons with numerical results are also presented.

Gas flow characteristics in shale fractures after supercritical CO2 soaking

2021 ◽  
Vol 88 ◽  
pp. 103826
Author(s):  
Yiyu Lu ◽  
Jiankun Zhou ◽  
Honglian Li ◽  
Jiren Tang ◽  
Lei Zhou ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Gas Flow ◽  
Flow Characteristics
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