煤质劣化对锅炉热量分配影响的机理分析

受能源供应紧张影响电厂经常燃用劣质煤,其主要特点是灰分、水分大而发热量低,以此特征为基础建立一种煤质劣化模型。利用炉内传热相似理论求解方法,以一300 MW燃煤机组炉膛结构设计为例分析了不同劣化程度的煤质对锅炉主要设计参数造成的影响。计算结果表明:随煤中水分和灰分增加单位辐射热量降低,并且水分的影响大于灰分;随煤灰分增加单位辐射热量与单位对流热量之比升高,但随水分增加而降低。高负荷时,随煤中水分和灰分增加炉膛出口烟温略微降低;低负荷时,随煤中灰分增加炉膛出口烟温略微降低,而随煤中水分增加略微升高。

Analysis influence mechanism of coal quality deterioration to boiler heat distribution

Power plants often use inferior coal due to shortage of energy supply.The main characteristics of poor-grade coal are large content of ash、moisture and low calorific.Based on its features,a model of coal quality deterioration was established.This paper mainly analyzed the impact of different degrees of coal quality deterioration on main parameters design of boiler with the furnace heat transfer theory method,with the example of furnace structure design of 300 MW coal-fired unit.The result shows that: unit radiation heat reduces as moisture and ash content in coal increase and the impact of moisture is greater than ash;with the ash increasing in coal,the unit ratio radiation heat increases with unit convection heat,but it reduces with moisture increasing in coal.At high load,with the moisture and ash increasing in coal,the gas temperature of furnace outlet lows slightly;At low load,with the ash increasing in coal,the flue gas temperature of furnace outlet reduces slightly,but with moisture increasing in coal,it rises slightly.