660 MW超临界对冲火焰锅炉水冷壁高温腐蚀原因探究

为了探究超临界对冲火焰锅炉高温腐蚀经常发生的原因及腐蚀机理,以某660 MW超临界对冲火焰锅炉为研究对象,通过燃煤特性分析、水冷壁的厚度测量、炉内水冷壁周围气氛条件测试,以及对腐蚀产物的SEM分析、EDS分析、XRD分析来研究引起水冷壁高温腐蚀的原因。研究结果表明：超临界对冲火焰锅炉水冷壁高温腐蚀主要发生在水冷壁两侧墙的各层燃烧器等高处的高温负荷区;炉内的高温腐蚀是不均匀的,主要是由煤燃烧产生的硫化物及燃烧所需氧与水冷壁高温氧化及高温硫化的作用造成;炉膛下部形成的还原性气氛条件,使H₂S浓度升高,该区域高温腐蚀更加严重。

Study on the Cause of High-Temperature Corrosion of Water Wall Tubes in a 660-MW Supercritical Opposed Firing Boiler

In order to explore the causes and the mechanism of frequent high-temperature corrosion in the supercritical opposed firing boilers, the cause analysis is carried out for a 600-MW boiler through the coal quality analysis, the waterwall thickness measurement, the waterwall surrounding atmosphere testing, and the corrosion products analysis by using SEM, EDS and XRD. The study results show that the waterwall high-temperature corrosion occurs mainly in the high-temperature load areas of the burners at all levels on both sides and spreads unevenly. The unevenness is attributed to the high-temperature sulfurization and oxidation caused by the sulfide and the oxygen in the combustion. In addition, the reducing atmosphere formed in the lower part of the furnace leads to the increase of the H₂S concentration making the high-temperature corrosion at this part worse.