600MW亚临界机组劣质煤掺烧试验研究

Research on Blending Combustion Testing on Fault Coal of 600MW Subcritical Unit

对某厂600 MW亚临界机组进行掺烧高水分、低发热量劣质煤后锅炉与制粉系统的带负荷能力、安全性与经济性等进行研究,结果表明:掺烧高水分、低发热量劣质煤会降低磨煤机干燥出力,影响锅炉带负荷能力与变负荷速率,锅炉高负荷运行时要减少劣质煤的掺混比例;掺烧高水分、高硫分的劣质煤,烟气酸露点明显升高,低温腐蚀加重;对于易结焦的劣质煤,通过"炉前掺混"的方式与不易结焦煤混烧能够明显减轻其结焦;过量空气和配风方式对锅炉效率影响大,倒塔型配风方式对减少劣质煤掺烧热损失和氮氧化物(NOx)生成有利;掺烧劣质煤会降低锅炉效率,但机组整体经济效益增加。

This paper studies load carrying capability,security and economy of the boiler and coal pulverizing system after 600 MW subcritical unit co-firing with fault coal of high moisture andlowcalorific value.Results indicate that blending combustion with fault coal of high moisture and low calorific value may reduce drying capacity of the pulverizer and affect load carrying capability and load variation rate of the boiler,so it is ought to reduce mixing proportion of fault coal when the boiler running with high load.Secondly,acid dew point of fuel gas obviously increases when co-firing with fault coal of high moisture and high sulfur content and low temperature corrosion aggravates as well.For fault coal easy to coking,it is able to obviously relieve coking by means of furnace mixing for co-firing with coal not easy to coking.Influence on the boiler efficiency is big by excessive air and air distribution mode while inverted-triangle air distribution mode is good for reducing heat loss of blending combustion with fault coal and producing NOx.In addition,blending combustion with fault coal may reduce boiler efficiency but entire economic benefit of the unit may increase.