600MW机组锅炉水冷壁区域还原性气氛影响因素分析

Influencing factors of reducing gas in water wall area of a 600 MW unit boiler

针对某电厂600MW机组锅炉水冷壁区域存在严重高温腐蚀的问题,通过试验研究了配风方式、运行氧量等因素对水冷壁区域还原性气氛的影响.结果表明：600 MW负荷常规运行方式下,锅炉水冷壁区域还原性气体体积分数较高,CO体积分数为10000～30000μL/L,H2S体积分数为80～130μL/L;与高负荷工况相比,中低负荷工况下,锅炉水冷壁近壁处的还原性气体体积分数下降明显;随着燃尽风风门挡板开度的减小,锅炉水冷壁近壁处烟气中CO体积分数明显降低;随着运行氧量的提高,锅炉水冷壁近壁处的还原性气体体积分数均有不同程度的降低,但下降幅度较小;相对于其他磨煤机运行方式,停中间磨煤机运行工况下,锅炉水冷壁区域还原性气体体积分数整体较低;煤中硫分的升高会使炉膛水冷壁区域H2S体积分数明显上升,建议尽量燃用低硫分煤种.

Serious high temperature corrosion occurred on water wall area of a 600 MW unit boiler. To solve this problem,the effects of the related factors on reducing atmosphere, such as the operation oxygen con- tent and air distribution methods,were investigated. The results show that, the concentration of reducing gas around the boiler water wall area was higher under normal operating mode with 600 MW load condi- tion,of which the volume fraction of CO was about 10 000-30 000 μL/L,and that of H2S was about 80- 130 μL/L. Compared with the high-load conditions,the concentration of reducing gas around the boiler wa- ter wall area decreased more significantly under low load conditions. With a decrease in air damper opening of over-fire air,the volume fraction of CO in water wall area of the boiler declined obviously. With an in- crease in the operation oxygen content, the concentration of reducing gas around the boiler water wall area decreased slightly. Compared with other operation modes of the mills, the overall concentration of reducing gas in the boiler wall area is low under conditions with intermediate mill outages. High sulfur content in the coal resulted in an obvious increase in volume fraction of H2 S in boiler water wall area. It is recommended to burn low- sulfur coal.