碱回收炉受热面腐蚀原因分析

Analysis of Corrosion Causes of Heating Surface of Alkali Recovery Furnace

关键词:  碱回收炉  黑液  SEM分析  XRD分析  腐蚀原因

Key Words:alkali recovery furnace  black liquor  SEM analysis  XRD analysis  causes of corrosion

摘要:本研究以某企业2200 tds/d碱回收炉为研究对象，通过分析黑液特性、测量碱回收炉受热面厚度变化，以及对水冷壁割管进行SEM分析及腐蚀产物XRD分析来研究碱回收炉运行中受热面腐蚀的原因。结果表明，碱回收炉在燃烧黑液过程中的腐蚀主要发生在中下层水冷壁墙面、各层燃烧器等高处的高温负荷区和局部低温受热面；碱回收炉内的腐蚀是不断扩散和加剧的，主要是由黑液燃烧产生的腐蚀气体、具有高温腐蚀性的可扩散腐蚀产物与高温氧化还原及硫化的作用造成；尾部气流速度场不均，导致低温受热面部位腐蚀；炉膛上部一级过热器烟气设计流速大，腐蚀和磨损交替破坏受热面。并对此提出了合理的防腐措施。

Abstract:In order to study the cause of serious corrosion of alkali recovery furnace in the operation, a 2200 tds/d alkali recovery furnace was taken as the research object. The causes of the corrosion of the heating surface of the alkali recovery furnace were studied by analyzing the characteristics of the black liquor, measuring the thickness changes of the heating surface, SEM analysis of the water wall cutting pipe and XRD analysis of the corrosion products. The results showed that during black liquor combustion the corrosion of the alkali recovery furnace mainly occurred in the high temperature load area and part of low temperature heating surface at the burners line places of each burners and water wall of the middle and lower layers. The corrosion in the furnace was continuously diffused and intensified, which was mainly caused by the action of corrosive gas produced by black liquor combustion, diffusible corrosion products with high temperature corrosiveness, high temperature oxidation-reduction and sulfuration. The uneven velocity field of the tail gas led to the corrosion of the low temperature heating surface. The higher design flow rate of the flue gas of the first stage superheater at the upper part of the furnace heating surface suffered from alternately corrosion and wear. Based on the finding of the research, the reasonable anticorrosion measures were put forward.