燃气轮机烟气SCR脱硝系统优化设计与工程应用

doi:10.12096/j.2096-4528.pgt.21029

摘要/Abstract

摘要：

以东莞某电厂F级燃气轮机卧式布置余热锅炉脱硝系统为例，针对氨气与烟气混合不均导致脱硝效率不达标的问题，采用数值计算、模型实验和工程实践研究了在喷氨栅格前增加导流板对脱硝系统的影响。数值模拟结果表明：增加导流板后，喷氨入口截面烟气速度梯度明显下降，催化剂床层入口截面烟气速度分布均匀。小试模型实验结果显示，增加导流板后，催化剂入口烟气速度偏差为10.7%，氨气浓度偏差为6.06%，表明烟气与氨气混合良好，流场均匀，满足设计要求。工程实践结果进一步证明，增加导流板后，催化剂床层出口截面NO_x浓度分布均匀，所有测点NO_x质量浓度小于30mg/Nm³，NO_x浓度偏差值小于15%，完全满足排放要求，表明优化方法具有较高实际应用价值。

关键词: 燃气轮机, 脱硝, 选择性催化还原(SCR), 喷氨格栅, 导流板

Abstract:

In order to solve the problem of low denitrification efficiency caused by the uneven mixing of ammonia and flue gas with an F-class gas turbine horizontal arranged waste heat boiler denitrification system, numerical simulations, lab-scale model experiments and engineering tests were carried out to study the effects of the approach of ammonia injection optimization. The numerical simulation results show that with adding a guide plate, the flue gas velocity gradient at the inlet plane of the ammonia injection decreases significantly, and the flue gas velocity distribution at the inlet plane of catalyst-bed is nearly uniform. The model experiment results show that the standard deviation of flue gas velocity at the catalyst-bed inlet plane decreases to 10.7%, and the standard deviation of ammonia concentration decreases to 6.06%. It indicates that the flue gas and ammonia are mixed well, and the flue gas velocity field is uniform. The engineering test results show that with the addition of the guide plate, the NO_x concentration in the outlet plane of the catalyst-bed is uniformly distributed, all the measured NO_x concentrations are less than 30mg/Nm³, and the NO_x concentration deviation is less than 15%, indicating that this method could effectively improve the denitrification system.

Key words: gas turbine, denitrification, selective catalytic reduction(SCR), spraying ammonia grille, guide plate

中图分类号:

TK47

黄友华, 马善为, 刘吉, 武正华. 燃气轮机烟气SCR脱硝系统优化设计与工程应用[J]. 发电技术, 2021, 42(3): 350-356.

Youhua HUANG, Shanwei MA, Ji LIU, Zhenghua WU. Optimization Design and Engineering Application of Gas Turbine SCR Denitrification System[J]. Power Generation Technology, 2021, 42(3): 350-356.

图/表 8

表1 不同位置布置喷氨格栅效果对比

Tab. 1 Effect comparison of spraying ammonia grilles in different positions

项目	电厂A	电厂B	电厂C
喷氨形式	大格栅	入口喷枪	扩散段格栅
运行情况	脱硝效率达标，氨逃逸超标	脱硝效率达标，氨逃逸超标	脱硝效率达标，氨逃逸超标
整改方法	增加分区数量，优化流场	优化流场	优化流场
效果	氨逃逸临界超标	氨逃逸超标	氨逃逸超标
产生原因	混合时间短，分区数量不足	喷枪数量少，流场分布不均	流场分布不均，分区数量不足

图1 F级燃气轮机脱硝系统布置示意图

Fig.1 Schematic diagram of denitrification system for an F-class gas turbine

图2 脱硝系统模型示意图

Fig.2 Schematic diagram of denitrification system model

图3 无导流板时不同入口截面的烟气流速分布

Fig.3 Velocity distributions of flue gas at different inlet sections without guide plate

图4 有导流板时不同入口截面的烟气流速分布

Fig.4 Velocity distributions of flue gas at different inlet sections with a guide plate

图5 SCR脱硝系统小试模型

Fig.5 Small test model of SCR denitrification system

图6 催化剂入口截面烟气流速和氨浓度分布云图

Fig.6 Distributions of flue gas velocities and ammonia concentrations at inlet section of catalyst-bed

图7 催化剂出口截面NOx浓度的分布

Fig.7 Distributions of NOx concentrations at outlet section of catalyst-bed

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