300 MW无烟煤锅炉选择性催化还原系统积灰原因分析

无烟煤锅炉由于挥发分含量低,着火困难,所以设计过程中都采用了较高的燃烧温度,从而导致选择性催化还原系统入口NOx排放浓度较高,脱硝系统压力较大。设计过程中灰颗粒尺寸选型不合理、灰黏性偏高、系统安装结构不合理以及喷氨量偏大等问题是引起脱硝系统积灰堵塞的主要原因。通过对脱硝系统优化改造和提高喷氨调整的自动化程度等,可以有效缓解选择性催化还原系统的堵塞情况;通过计算氨氮摩尔比,可以对氨逃逸浓度的测量结果进行校核。

Ash Deposition Reason Analysis for SCR of 300 MW Anthracite Boiler

The anthracite boiler usually adopts higher furnace temperature,because of its lower volatile and higher ignition temperature.The concentration of NO_x at selective catalytic reduction(SCR) system entrance is higher as a result of higher furnace temperature.In a lot of SCR systems,the amount of injecting ammonia are exceeded,and the system is blocked with the ash.The reason of system blocking is that the fineness of ash is chosen unreasonably,the stickiness of ash is higher,the system assembling has defects.Through optimization and reconstruction of flue gas system and improving the level of automation,the SCR system blocking is relieved.The measurement result of ammonia escape concentration could be checked by the calculation results of ammonia nitrogen mole ratio.