针对管式空预器磨损、腐蚀和堵塞等问题，以河坡350 MW超临界循环流化床锅炉机组为例，通过空预器入口风温智能温控策略，根据酸露点的预测结果确定空预器管壁温度，从而调整暖风器出力，保证空预器的入口风温始终在酸露点以上，从而减小空预器末端低温腐蚀。结合低氧量燃烧技术，通过运行试验，最终确定锅炉在不同负荷下的氧量：350 MW负荷时氧量为2.7%～3.0%，310 MW负荷时氧量为3.0%～3.2%，230 MW负荷时氧量为3.2%～3.5%，有效减少了空预器低温段腐蚀。采用二次风口喷入石灰石快速响应炉内脱硫技术，使石灰石可以直接喷入炉内微氧化稀相区域，缩短了脱硫响应速率时间，减少了炉内脱硫剂石灰石的用量，避免了烟气中SO2含量大幅波动，有效提高炉内脱硫效率。对比各脱硝喷枪效率以及脱硝喷枪的位置，确定喷枪效率，对SNCR系统的喷枪进行优化，在二次风管倾斜段增设脱硝喷枪，提高了全负荷平均脱硝效率，降低氨逃逸量，有效减少了该机组脱硝还原剂的消耗量，并且大幅降低氨逃逸硫酸氢氨对空预器腐蚀和堵塞的风险。通过以上技术手段，空预器运行6 a来，工作状态良好，运行平稳，可为同类机组空预器的运行维护提供参考。

In view of problems such as abrasion,corrosion and blockage of tubular air preheater,and taking Hepo 350 MW supercritical circulating fluidized bed boiler unit as an example,the pipe wall temperature of air preheater is determined according to the prediction results of acid dew point through the intelligent temperature control strategy of air preheater inlet air temperature,so as to adjust the output of air heater,ensure that the inlet air temperature of air preheater is always above the acid dew point,so as to reduce the low-temperature corrosion at the end of air preheater. Combined with low oxygen combustion technology,the oxygen content of the boiler under different loads is finally determined through operation tests:2.7%-3.0% under 350 MW load,3.0%-3.2% under 310 MW load,and 3.2%-3.5% under 230 MW load,which effectively reduces the corrosion of the low temperature section of the air preheater. The secondary air inlet is used to inject limestone into the furnace to quickly respond to the desulfurization technology in the furnace,so that limestone can be directly injected into the micro oxidation dilute phase area in the furnace,shortening the desulfurization response time,reducing the amount of limestone used as the desulfurization agent in the furnace,avoiding the sharp fluctuation of SO2 content in the flue gas,and effectively improving the desulfurization efficiency in the furnace. By comparing the efficiency of each denitration spray gun and the position of the denitration spray gun,determining the high and low order of the spray gun efficiency,optimizing the spray gun of the SNCR system,increasing the setting of denitration spray gun in the inclined section of the secondary air duct,the average denitration efficiency under full load is improved,the amount of ammonia escape can be reduced,the consumption of denitration reducing agent of the unit is effectively reduced,and the risk of ammonia escape hydrogen sulfate ammonia corrosion and blockage of the air preheater are greatly reduced. Through the above technical means,the air preheater has been operating for 6 years,working in good condition and stable operation,which can provide reference for the operation and maintenance of air preheaters of similar units.

0 引言

1 锅炉设备介绍

2 空预器运行策略

   2.1 入口风温控制

   2.2 低氧量燃烧

   2.3 脱硫系统改造

   2.4 脱硝系统改造与调整

   2.5 空预器主动封堵措施

3 结论