燃煤电厂烟气冷却器壁上沉积物分析和形成机理

选择性催化还原(SCR)系统和烟气冷却器是实现燃煤电厂节能减排的重要设备,但SCR中的氨逃逸现象对烟气冷却器的影响研究鲜有报道。本文对某电厂SCR设备后的烟气冷却器表面出现的沉积物,进行了XRD、XRF、SEM和EDS等分析研究。结果表明:沉积物的白色结晶物主要为氟硼酸铵,及其反应中间产物(氟化铵、硼酸以及氟硅酸铵),形成该结晶层的主要原因为煤中富集的氟、硼元素和SCR逃逸氨的耦合反应,该沉积物的厚度不会无限增加,但仍会影响烟气冷却器的正常运行。

Analysis and formation mechanism of condensates on surface of flue gas cooler of coal-fired power plant

Two kinds of important equipment i.e. selective catalytic reduction system (SCR) and flue gas cooler are applied in coal-fired power plant to achieve energy conservation and to reduce emission. However, few studies have been published on the influence of ammonia escaped from SCR system on flue gas cooler. In this study, the condensates deposited on the wall of the cooler at the downstream of SCR were analyzed by XRD, XRF, SEM and EDS. The results indicated that the white crystalline material in the condensates is mainly ammonium fluoroborate and some intermediates such as ammonium fluoride, boric acid and ammonium fluorosilicate. The formation of crystalline layer took place by coupling reaction between the ammonia escaped from SCR system and both fluorine element and boron element volatilized in combustion of coal. Although the deposition layer has only a limited thickness, it could be hamper directly for operation of flue gas cooler.