氨氮比分布不均对SCR脱硝反应影响的模拟研究

Simulation Study of Effects of Nonuniform Distribution of NH_3/NO Ratio on De-NO_x Reaction

建立了某660 MW机组SCR主反应器的三维数值模型,通过模型研究了反应器内氨氮比的分布特点及其均匀性对脱硝反应的影响。模拟结果表明:在氨氮比小于1的前提下,每经过一层催化剂脱硝,氨氮比变小,而其分布的不均匀程度变大;同时,氨氮比分布不均降低脱硝效率,增大氨逃逸。并且随着脱硝效率的增大,氨氮比分布不均对其影响越显著;氨氮比的均匀性是限制SCR满足一定氨逃逸的前提下,进一步提效的关键因素。

A three dimensional numerical model of SCR of 660MW power unit was established, the distribution characteristics of NH3/NO ratio and the effects of it＇s distribution uniformity on the reaction was studied by the model. The results show that ： Under the premise of NH3/NO ratio less than 1, the NH3/NO ratio become smaller while the distribution of NH3/NO ratio become more uneven through every catalyst layer： At the same time, the NH3/NO ratio distribution can reduce the De-NOx efficiency, increase ammonia escape. And the influence become more remarkable as the De-NOx efficiency become higher： The uniformity of NH3/NO ratio is the key factor which limit the improvement of De-NOx efficiency also meet the certain ammonia escape.