660MW机组锅炉掺烧褐煤对煤粉输送和运行成本的影响

Influence of blending lignite with bituminous coal on coal feeding safety and operational costs for a 660MW unit boiler

在超超临界660 MW机组上进行了褐煤间接掺混（炉内掺混）的试验研究,从制粉系统试验和褐煤掺烧试验两方面,对系统掺烧后运行的安全性和经济性进行了评估。结果表明：中速磨煤机从研磨单一烟煤改为单一褐煤后,为了保证褐煤出力量一致,褐煤的颗粒细度稍有变大；对于收到基水质量分数为30％的褐煤,无需添加脱水装置,仅通过磨煤机内预热即可保证一次风管道内煤输送的安全性；磨煤机内阻力增加后,保证一次风进口压力并控制一次风出口温度在55~65℃,是保证磨煤机安全运行的关键；掺烧褐煤对锅炉系统热效率影响较小,当褐煤与烟煤的单价差在50元以上时,可有效降低企业运行成本。

Experimental investigations on indirect blending lignite with bituminous coal were carried out on an ultra supercritical 660 MW unit.On the basis of pulverizing system test and lignite co-combustion test, the operation safety and economy of the system after co-firing lignite was evaluated.The results show that, after the medium speed roller mill was retrofitted from grinding single lignite to single lignite coal,to en-sure the same lignite particle production,the particle size will increase a little.In term of raw lignite with moisture mass ratio of 30%,the heating process in mill can guarantee the stability and safety of coal feed-ing in the primary air pipeline,in which no additional heating device was required.After the resistance in-side the coal mill increased,the primary air inlet pressure and its outlet temperature （5 5 ℃ to 6 5 ℃）in mill are two factors to ensure the operation safety.Blending lignite affects little on the boiler thermal efficiency. When the price difference between lignite and bituminous coal reaches about 50 yuan,the operation cost in the power plant will be reduced effectively.