燃煤机组锅炉低负荷运行时,易出现脱硝系统入口烟温偏低导致选择性催化还原反应(SCR)烟气脱硝系统无法正常投运,以及一次风温低、制粉系统干燥出力不足等问题.本文以某600 MW燃煤机组为例,提出了综合改造方案即割除部分水平低温过热器及高温省煤器换热面积,增加 SCR 脱硝系统后换热面,优化管式空气预热器(空预器)入口烟气流场.实施改造后,300 MW负荷下,管式空预器中出口一次风温提高26 ℃,SCR脱硝系统入口烟温提高 28 ℃,制粉系统干燥出力提高,脱硝装置适应低负荷调峰能力增强.该技术的成功应用为同类型机组实施技术改造提供了思路.%When coal-fired boiler is running at low load, there are some problems, such as the low inlet gas temperature causing SCR denitration system to be unable to operate normally, the low primary air temperature, and the insufficient drying capacity of the pulverizing system. In this study, taking a 600 MW coal-fired unit as an example, a comprehensive transformation scheme is proposed for cutting off part of the heat exchange surface of the horizontal low-temperature superheater and high-temperature economizer, increasing the heat exchange surface at the outlet of the SCR denitration system, and optimizing the flue gas flow field at the inlet of tubular pipe air preheater. After the transformation, under the load of 300 MW, the primary air temperature at the outlet of tubular pipe air preheater is increased by 26 ℃, the gas temperature at the inlet of the SCR denitration system increases by 28 ℃, the drying capacity of the pulverizing system is enhanced, and the adaptive ability of the SCR denitration system to depth peak regulation is greatly improved. The successful application of this technology provides ideas for the technical transformation of the same type of units.
展开▼
