催化剂的非均匀分布对船舶SCR系统特性的影响
Influence of non-uniform distribution of catalysts on the characteristics of ship SCR system
梁海明 1许红祥 2雷小霞 3陈正科 2潘光明4
作者信息
- 1. 广西交通职业技术学院汽车工程学院
- 2. 江西科技学院人工智能学院
- 3. 南昌工学院
- 4. 燕山大学机械工程学院
- 折叠
摘要
选择性催化还原(SCR)系统常用于降低柴油发动机尾气排放出的氮氧化物(NOx).为进一步提高其脱硝性能,首先建立三维数值模拟模型,通过改变SCR转换器中孔隙率来实现催化剂的非均匀分布,从而研究在不同发动机负荷下的催化剂非均匀分布对SCR系统中的流动、传质和传热等性能的影响;其次,与催化剂的均匀分布进行对比,重点考察催化剂非均匀分布时对SCR系统性能的影响;最后,基于场协同原理分析SCR系统中的速度场和温度场对传热过程的影响.结果表明:催化剂的非均匀分布可以提高SCR系统的性能.在发动机25％的负荷下,与均匀分布相比,案例P-R5的压力损失降低165 Pa,脱硝率提高了 0.8％,氨的逸出量减少了 7 mg/L;案例P-R5的温度梯度高于均匀孔隙率催化剂温度梯度的最大峰值,这表明向外部传递的能量较少,催化剂非均匀分布的结构可以保持催化区域的温度,提高催化剂的活性,有利于脱硝反应.
Abstract
Selective catalytic reduction(SCR)systems are typically used to reduce nitrogen oxides(NOx)emitted from diesel engine exhaust emissions.To further improve its de-NOx performance,firstly,a three-dimensional numerical simulation model was established.The non-uniform distribution of the catalyst was achieved by changing the porosity in the SCR converter,and the impact of the non-uniform distribution of the catalyst under different engine loads on the flow,mass transfer,and heat transfer performance of the SCR system was investigated.Secondly,the impact of the non-uniform distribution of the catalyst on the performance of the SCR system was examined and compared with that of the uniform distribution.Finally,based on the principle of field synergy,the influence of velocity and temperature fields on the heat transfer process in the SCR system was analyzed.The results indicate that the non-uniform distribution of catalysts can improve the performance of SCR systems.At 25％engine load,compared to a uniform distribution,the pressure drop of Case P-R5 is reduced by 165 Pa,the conversion efficiency of NOx is increased by 0.8％,and the escape of ammonia is reduced by 7 mg/L.In addition,the temperature gradient of Case P-R5 is higher than the maximum peak of the temperature gradient of the catalyst with uniform porosity,indicating that there is less energy transferred to the outside.The non-uniform distribution of the catalyst structure can maintain the temperature of the catalytic region,improve the catalyst activity,and facilitate de-NOx reactions.
关键词
SCR系统/压力损失/反应特性/脱硝率/非均匀分布Key words
SCR system/pressure drop/reaction characteristics/denitration efficiency/non-uniform distribution引用本文复制引用
基金项目
广西交通运输行业重点科技项目(第三批)(2020)(JZY2020KZD04)
出版年
2024
NETL
NSTL
万方数据