Urea SCR System Development for Large Diesel Engines

Zheng, Guanyu; Wang, Fengshuang; Wang, Sheng; Gao, Wei; Zhao, Zhiguo; Liu, Jian; Wei, Lin; Wu, L H; Wang, Hongyu

doi:10.4271/2014-01-2352

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…SCR operating costs comprise urea cost, maintenance cost, and catalyst replacement cost. The reducing agent in marine applications is 35-40% solution of urea in de-ionized water [53]. Urea dosing for target reduction ∆NO x (g/kWh) is given by multiplying the target by 0.652.…”

Section: Selective Catalytic Reduction Systemmentioning

confidence: 99%

Emission Abatement Technology Selection, Routing and Speed Optimization of Hybrid Ships

Ritari

Spoof-Tuomi

Huotari

et al. 2021

JMSE

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This paper evaluates the effect of a large-capacity electrical energy storage, e.g., Li-ion battery, on optimal sailing routes, speeds, fuel choice, and emission abatement technology selection. Despite rapid cost reduction and performance improvement, current Li-ion chemistries are infeasible for providing the total energy demand for ocean-crossing ships because the energy density is up to two orders of magnitude less than in liquid hydrocarbon fuels. However, limited distance zero-emission port arrival, mooring, and port departure are attainable. In this context, we formulate two groups of numerical problems. First, the well-known Emission Control Area (ECA) routing problem is extended with battery-powered zero-emission legs. ECAs have incentivized ship operators to choose longer distance routes to avoid using expensive low sulfur fuel required for compliance, resulting in increased greenhouse gas (GHG) emissions. The second problem evaluates the trade-off between battery capacity and speed on battery-powered zero-emission port arrival and departure legs. We develop a mixed-integer quadratically constrained program to investigate the least cost system configuration and operation. We find that the optimal speed is up to 50% slower on battery-powered legs compared to the baseline without zero-emission constraint. The slower speed on the zero-emission legs is compensated by higher speed throughout the rest of the voyage, which may increase the total amount of GHG emissions.

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Section: Selective Catalytic Reduction Systemmentioning

confidence: 99%

Emission Abatement Technology Selection, Routing and Speed Optimization of Hybrid Ships

Ritari

Spoof-Tuomi

Huotari

et al. 2021

JMSE

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“…A modeling method was applied for analyzing NOx conversion efficiency impact aspects by considering the NH 3 storage capability in a DOC+DPF+SCR aftertreatment system [7]. Computational fluid dynamics (CFD) analysis was used to optimize aftertreatment packaging design for better SCR performance and higher NOx conversion efficiency [8][9][10]. Ammonia slip catalyst (ASC) was considered as an aftertreatment to reduce NH 3 slip [11,12].…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Aftertreatment SCR Sizing Strategy for a Nonroad Mid–Range Diesel Engine

2020

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Urea-Selective Catalytic Reduction (SCR) is widely used to reduce nitrogen oxide (NOx) emissions. This paper presents a comprehensive experimental research work on aftertreatment emissions of NOx and ammonia (NH3) slip for three aftertreatment concepts by introducing the SCR sizing strategy on a 6-cylinder mid-range non-exhaust gas recirculation (EGR) diesel engine to meet China non-road Stage IV regulation limits. It can be observed that the three concepts could meet the regulation limits for NOx emissions and NH3 slip by selecting the appropriate length. There is little effect on emission results during a non-road transient cycle (NRTC) when the aftertreatment inlet/outlet with insulation and without insulation and the emission results on both strategies could meet non-road China Stage IV regulation limits. It is recommended to select Concept 2 which could meet regulation requirements considering multiple factors in the SCR sizing strategy. Substrate impact and NH3/NOx molar ratio (ANR) impact are investigated based on Concept 2. The results show that by applying the SCR substrate aftertreatment with a cell density of 600 cpsi, NOx conversion capability is stronger than that with cell density 400 cpsi for the same SCR size. Current dosing strategy is capable and recommended ANR is 0.9–1.1 if considering dosing strategy optimization. The methodology in this study provides an effective guidance and reference for future aftertreatment SCR sizing strategies in real applications.

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“…Although NO x conversion can be improved by increasing the NH 3 /NO x ratio, this is at the cost of unreacted ammonia exiting the converter, which is undesirable. Moreover, it is known that insufficient residence time or urea deposition on the walls of the mixing chamber can cause incomplete conversion of urea. , In the experimental studies reported by Yamauchi et al and Tamaldin et al, most of the urea droplets from the injection entered the SCR unconverted. Even in the case of complete urea conversion to ammonia, improper mixing within the chamber can lead to nonuniform ammonia concentration distribution across the cross section.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Effect of Nonuniformities from Urea Injection on SCR Performance Using CFD

Dammalapati

Aghalayam

Kaisare

2019

Ind. Eng. Chem. Res.

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A computational fluid dynamics model, consisting of a mixing chamber coupled with a catalytic converter, is developed for the selective catalytic reduction (SCR) of NO x using urea. The NH3 required for the SCR reactions is produced from the injection and decomposition of urea in the mixing chamber. The conversion efficiency and concentration distribution of NH3 from the mixing chamber are analyzed for a range of operating conditions. The flow and species distribution profiles from the mixing chamber are incorporated as inlet boundary conditions at the entrance of the downstream SCR convertor. The SCR convertor comprises a central catalytic monolith and inlet and outlet diffuser sections. Variations in NO x concentration were observed within the monolith due to heat losses and nonuniformities in ammonia concentrations. While heat effects under non-isothermal conditions slightly improved the NO x conversion efficiency, nonuniformities in ammonia concentrations did not significantly influence the SCR performance. Thus, the radial variations in NH3 concentrations, owing to nonuniformity at the outlet of the mixing chamber, did not considerably impact the overall performance of the SCR. The effects of temperature, NO:NO2 ratio, and inlet velocity were investigated.

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Urea SCR System Development for Large Diesel Engines

Cited by 5 publications

References 10 publications

Emission Abatement Technology Selection, Routing and Speed Optimization of Hybrid Ships

Emission Abatement Technology Selection, Routing and Speed Optimization of Hybrid Ships

Experimental Research on Aftertreatment SCR Sizing Strategy for a Nonroad Mid–Range Diesel Engine

Modeling the Effect of Nonuniformities from Urea Injection on SCR Performance Using CFD

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