电站锅炉SCR烟气脱硝系统优化数值模拟

Numerical Simulation on Optimization of SCR Denitrification System for Coal-fired Boilers

针对某电厂300MW锅炉的选择性催化还原(SCR)反应系统,采用计算流体力学软件对不同结构下SCR反应器的脱硝特性进行了数值模拟,分析了导流板布置对SCR反应器内流场分布均匀性的影响,研究了不同布置方案下SCR反应器内氨氮物质的量比(简称氨氮比)分布的规律.结果表明:烟道内无导流板时,SCR反应器内的流场和NH3体积分数分布严重不均,SCR反应器的脱硝效率较低,氨逃逸率较高;采用初始方案,SCR反应器内的流场改善较大,但是第一层催化剂入口处氨氮比分布偏差大于5%;采用最终方案,第一层催化剂入口处的速度偏差为3.84%,氨氮比分布偏差为3.79%,SCR反应器的脱硝效率达到83%,NH3逃逸率低于5×10-6.

Taking the selective catalytic reduction （SCR） reaction system of a an example, numerical simulation was made to the denitration characteristics 300 MW coal fired of the SCR reactor boiler as with dif- ferent structures by fluid mechanics calculation software, so as to analyze the effects of guide plate layout on distribution of both the flow field and the ammonia-nitrogen ratio in the SCR reactor. Results show that both the flow field and NHa volume fraction within the SCR reactor are severely uneven, the denitration ef- ficiency of SCR reactor is relatively low and the ammonia escape rate is relatively high, when there is no guide plate installed in the flue; by adopting the initial solution, the flow filed in the SCR reactor is im- proved greatly, but the deviation of ammonia-nitrogen ratio distribution at inlet of the first catalyst layer is more than 5% ; whereas, in the final solution, the deviation of velocity distribution at inlet of the first cat alyst layer is 3.84%, where the deviation of ammonia-nitrogen ratio distribution is 3. 79%, the denitration efficiency of SCR reactor reaches 83%, and the NH3 escape rate is lower than 5X10 6.