污泥掺烧工况下空预器的积垢成因分析及除垢方法研究  

Analysis on the Causes of Fouling in Air Preheater under Sludge Co-Burning Conditions and Research on the Methods of Descaling

作　　者：朱宇翔 ZHU Yuxiang(Shanghai Shenxin Environmental Protection Industry Co.,Ltd.)

机构地区：[1]上海申欣环保实业有限公司

出　　处：《上海节能》2024年第10期1682-1691,共10页Shanghai Energy Saving

摘　　要：城市废水污泥作为低热值燃料与燃煤掺混进入锅炉燃烧,污泥与燃煤按照一定比例掺混不会影响锅炉的燃烧。污泥与燃煤的掺混使燃料的水分、灰分甚至硫分等成分发生了变化,燃烧后烟气成分也相应发生变化,空预器发生结垢堵塞现象的风险加剧。针对上海某电站锅炉在掺烧8%左右污泥空预器的结垢现象进行研究,通过对垢样的分析,发现结垢的垢样中含硫酸氢铵(NH_(4)HSO_(4))成分,硫酸氢铵黏性强,吸附飞灰形成较为坚硬的垢物。而硫酸氢铵的生成析出与烟气的三氧化硫(SO_(3))的浓度与氨(NH3)浓度比例,含水率及温度场相关,空预器提供的温度场正好满足硫酸氢铵的生成析出。依据结垢机理进行了阻垢和除垢的方法研究,确认投入钙碱中和烟气的三氧化硫,可降低硫酸氢铵的生成量,有效地缓减垢的生成。提高温度并投入钙碱,垢中的硫酸氢铵会与钙碱反应,生成硫酸钙(CaSO_(4))及气态氨和二氧化碳(CO_(2))等。黏性物质硫酸氢铵的解析后降低了垢的黏合度,同时反应后气态生成物还可起到疏松垢体作用,从而起到解垢的效果。Urban wastewater sludge is mixed with coal as a low calorific value fuel and enters the boiler for combustion.Mixing sludge and coal in a certain proportion will not affect the combustion of the boiler.The blending of sludge with coal changes the moisture,ash and even sulfur content of the fuel,and the composition of the flue gas after combustion also changes accordingly,increasing the risk of fouling and clogging in the air preheater.A study was carried out on the fouling phenomenon of an air preheater of a power station boiler in Shanghai when burning about 8%sludge.Through the analysis of the scale samples,it was found that the scaled scale samples contained ammonium bisulfate(NH_(4)HSO_(4)).Ammonium bisulfate was highly viscous and absorbed fly ash to form relatively hard scale.The formation and precipitation of ammonium bisulfate is related to the ratio of sulfur trioxide(SO_(3))concentration to ammonia(NH3)concentration in the flue gas,water content and temperature field.The temperature field provided by the air preheater just meets the formation and precipitation of ammonium bisulfate.Based on the scale formation mechanism,the method of scale inhibition and scale removal was studied,and it was confirmed that adding calcium alkali to neutralize the sulfur trioxide in the flue gas can reduce the production of ammonium hydrogen sulfate and effectively slow down the production of scale.Increase the temperature and add calcium base.Ammonium bisulfate in the scale will react with calcium base to produce calcium sulfate(CaSO_(4)),gaseous ammonia and carbon dioxide(CO_(2)).The analysis of the viscous substance ammonium bisulfate reduces the adhesion of scale,and the gaseous products after the reaction can also play a role in loosening the scale,thus achieving the effect of removing scale.

关 键 词：污泥掺烧 垢 钙碱 硫酸氢铵 

分 类 号：TM621.2[电气工程—电力系统及自动化] X703[环境科学与工程—环境工程]