大型燃煤锅炉SNCR脱硝的数值模拟

为了给大型燃煤锅炉采用选择性非催化还原(SNCR)脱硝技术提供参考和指导,本文借助计算流体力学软件平台Fluent,通过数值模拟的方法研究了一台600 MW燃煤锅炉上的SNCR脱硝过程。计算结果表明大型燃煤锅炉上温降梯度较大,温度适宜进行SNCR脱硝反应的炉内空间较小。根据温度分布,锅炉满负荷运行时,SNCR脱硝系统投用还原剂喷射3区、4区和5区的喷枪比较合适。在氨氮摩尔比为1.1的条件下,该燃煤锅炉上SNCR脱硝效率在27%左右。向炉内喷入少量的添加剂一氧化碳(CO)可以加快SNCR反应的速率,减少NH3漏失。

Numerical Study of SNCR Process in Large Coal Fired Utility Boiler

To provide reference and guidance for the application of selective non-catalytic reduction（SNCR） in large capacity coal-fired boiler,numerical study of SNCR process in a 600 MW coal-fired boiler was conducted by means of computational fluid dynamics code Fluent.The calculation results show that temperature drop rate is high and the furnace space with suitable temperature for SNCR reaction is small.According to the temperature distribution,the reducing regent injection zone3,zone4 and zone5 are practicable for full load operation of boiler.When the molar ratio of NH3 and NO is 1.1,the NO removal efficiency can reach 27% roughly in this boiler.Adding a spot of CO to the furnace can increase the SNCR reaction rate and decrease NH3-slip.