脱硝反应器内烟气与飞灰分布差异的数值模拟

摘要

Ash accumulation is one of the critical problems affecting the performance and secure operation of SCR de-NOx system in coal-fired power plants.Unfortunately,the fly ash concentration field is often neglected in traditional engineering design.In this paper,the ash accumulation states of a certain 600 MW coal-fired power plant was studied.The calculation model was established according to CFD method and the distribution of flue gas flow field and fly ash concentration in de-NOx reactor was simulated.Also a structure optimization was established to improve the distribution of flue gas and fly ash.The results indicated that the distribution characters of fly ash decreases with the increase of particle size and density of fly ash particles.The high concentration and density of fly ash particles can easily lead to the clogging of the catalyst layer,which may lead to the serious problem.The distribution of flue gas flow field and fly ash should be demonstrated to ensure the safe and efficient operation of the device when the fly ash concentration field is designed.%火电SCR脱硝反应器催化剂层积灰现象是影响脱硝性能和安全运行的重要因素之一,而传统工程导流设计方法中飞灰浓度场的分布易被忽视.以某600 MW机组脱硝装置实际积灰情况为例,运用多相流体力学模拟方法建立多相流模型,研究了反应器内烟气流场及飞灰浓度场的分布特征,并通过增设导流板的方式对烟气及飞灰流动状态进行了优化调整.研究结果表明,飞灰浓度场分布均匀性随飞灰颗粒的粒径和真密度增加而下降,飞灰颗粒浓度或真密度较高工况极易造成催化剂层积灰堵塞,导致故障.在制定脱硝装置导流设计方案时,应论证烟气和飞灰的均布性,以确保装置安全高效投运.