超超临界1000 MW机组锅炉水冷壁壁温偏差计算分析及对策

Water wall temperature deviation of an ultra-supercritical 1 000 MW unit boiler: analysis and countermeasures

针对平顶山电厂超超临界机组直流锅炉水冷壁壁温偏差过大的问题,本文根据锅炉结构特点和对冲燃烧特性,建立了1 000 MW机组对冲燃烧锅炉水动力计算模型,并通过对比计算结果和试验实测数据,反推锅炉热负荷分布,分析了造成锅炉水冷壁壁温偏差过大的原因,提出了相关应对措施。研究结果表明:该机组锅炉水冷壁壁温偏差过大主要是由炉膛内热负荷不均和流量分配不均引起,同时锅炉结构也对壁温偏差的敏感度有一定的影响;在高电负荷时,计算结果与实测数据能够较好地吻合,但中低电负荷时,水冷壁吸热偏差较大,通过反推,修正了热负荷分布,发现计算值与实测结果接近。建议在运行过程中注意调整同层旋流燃烧器的风粉均匀分配,在变负荷或扰动工况时控制好煤水比,在锅炉设计方面可以调整进入上炉膛前墙和后墙的流动截面比,使流量均匀分配。

To solve the large water wall temperature deviation problem occurred on ultra supercritical 1 000 MW unit boiler of Pingdingshan Power Plant, a mathematical model for the 1 000 MW unit boiler was established according to the boiler structure and the heat load distribution features in the furnace. By comparing the calculated results and the measured data, the boiler heat load distribution was deduced, and the reasons for the excessive deviation of the boiler water wall temperature were analyzed. The results show that, the uneven heat load and uneven flow distribution in the furnace mainly leads to the large temperature deviation. In addition, the structure of the boiler has a certain influence on sensitivity of the wall temperature deviation. The calculation results and the measured data can be in good agreement at high load. But there is a big difference between the calculated steam temperature and the measured data. However, when the heat load distribution in the furnace is modified time after time, it indicates that the calculation results agree with the field data well. It suggests to adjust the uniform distribution of pulverized-coal and air in the same layer swirl burner during the operation. The ratio of coal to water should be controlled under variable load or disturbance conditions. Moreover, in boiler design, the flow cross ratio of the front wall and the back wall in the upper furnace can be adjusted, so that the flow can be evenly distributed.