Mixer Development for Urea SCR Applications

Zheng, Guanyu; Palmer, Guenter; Salanta, Gabriel; Kotrba, Adam

doi:10.4271/2009-01-2879

Cited by 53 publications

(28 citation statements)

References 2 publications

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“…Fig. 5 shows uniformity index of NH 3 . Uniform distribution of NH 3 is required to minimize NH 3 slip and to maximize de-NO x efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…4 shows the NH 3 conversion rate at each position along downstream of SCR system. NH 3 conversion rate is defined as the ratio of an amount of NH 3 production to the maximum amount of NH 3 when UWS is totally converted into NH 3 . Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Thakur et al gave guidelines for the selection of static mixers [2]. Zheng et al was defined the scope of the mixer development for given exhaust flow configurations [3], [4]. They also defined the main causes of [6], [7].…”

Section: Introductionmentioning

confidence: 99%

“…As a reducing agent, urea water solution (UWS) is preferred to gaseous NH 3 because of its toxicity and storage problems. UWS is decomposed and generates gaseous NH 3 . Urea decomposition processes are divided into thermolysis and hydrolysis, and they can be expressed as follows:…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of Urea Decomposition with Static Mixers in Marine SCR System

Choi¹,

Sung²,

Choi³

et al. 2015

JOCET

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Abstract-A numerical simulation for urea decomposition into ammonia with static mixers was performed for marine selective catalytic reduction. Three types of mixer were considered to improve urea into ammonia conversion rate. The effect of each mixer such as pressure drop, particle residence time, and uniform distribution of urea water solution was investigated using three dimensional CFD code. Using mixer regardless of a type was improved urea decomposition. Engine performance could be affected by high pressure drop caused by mixer. Therefore, the proper mixer should be chosen in permissible level of pressure drop as well as ammonia conversion rate.Index Terms-Selective catalytic reduction (SCR), static mixer, urea decomposition, urea water solution (UWS).

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“…Fig. 5 shows uniformity index of NH 3 . Uniform distribution of NH 3 is required to minimize NH 3 slip and to maximize de-NO x efficiency.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Analysis of Urea Decomposition with Static Mixers in Marine SCR System

Choi¹,

Sung²,

Choi³

et al. 2015

JOCET

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show abstract

“…In SCR a reducing agent is injected into the exhaust pipe 3 for removal of harmful NOx emissions through several steps. Normally H2, CO [4][5][6] , hydrocarbons [7][8][9] and urea-water solution (UWS) 10,11 are the preferred reducing agents. As soon as the urea-water solution is injected into the exhaust tailpipe, water will evaporate to leave a trail of solid molten urea, which will convert into gaseous ammonia.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Urea Decomposition and Uniform Concentration of Urea Water Solution in SCR System for Diesel Engine Exhaust Using CFD

2017

Rasayan J Chem

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Urea-SCR has received worldwide attention for reducing the harmful NOx emission from present diesel engines. But this faces lot of challenges such as complete decomposition of reducing agent urea and its deposition at the bottom of exhaust tail pipe, lack of uniform distribution of the urea-decomposed ammonia during the continuous running of the engine. This study is involved with CFD evaluation of urea decomposition rate by adopting different urea injection angles and nozzle positions. Also, urea atomization and evaporation/decomposition to ammonia and ammonia distribution on tail pipe cross-sectional area are investigated. Exhaust tail pipe is fitted with guided pipe at different angles. Also, urea and air are injected at different pressures respectively, in the twin-flow nozzle. The CFD analysis indicated that, the ammonia conversion rate is well improved using guided pipe fitted at 30 o inclination with exhaust tail pipe. The CFD analysis is validated by engine experiments. It was proven that, the conversion increased for the 5bar urea and 1bar air.

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Experimental investigation on the urea injection and mixing module for improving the performance of urea‐SCR in diesel engines

Liu

2017

Can J Chem Eng

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In a urea selective catalytic reduction (urea‐SCR) system for diesel engines, the atomization, evaporation, and mixing conditions of urea water solution (UWS) play a crucial role for NOX conversion and ammonia slip in the SCR process. In this paper, a series of novel mixing modules were proposed to improve UWS evaporation, mixing, and distribution for NOX reduction in the SCR system. Experimental investigations were conducted on the performances of the existing and developed mixing modules under various engine test conditions, including particle size test, NOX conversion efficiency, flow bench tests, etc. To determine ammonia slip, the urea and ammonia distribution patterns were constructed and the non‐uniformity index was then calculated. Compared with the baseline (without mixing module) and existing mixing module, the NOX conversion efficiency of the SCR system with a developed mixing module is improved by 37.7 and 14.1 % at maximum, respectively. Furthermore, ammonia slip and distribution are ameliorated significantly with low‐pressure drops simultaneously. Among the mixing modules, Concept 3 design exhibits superior performance under the engine test conditions.

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Mixer Development for Urea SCR Applications

Cited by 53 publications

References 2 publications

Numerical Analysis of Urea Decomposition with Static Mixers in Marine SCR System

Numerical Analysis of Urea Decomposition with Static Mixers in Marine SCR System

Investigation of Urea Decomposition and Uniform Concentration of Urea Water Solution in SCR System for Diesel Engine Exhaust Using CFD

Experimental investigation on the urea injection and mixing module for improving the performance of urea‐SCR in diesel engines

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