高温供热管网中316L不锈钢防点蚀策略研究

Research of Anti-pitting Strategy of 316L Stainless Steel in High Temperature Heating Network

供热管网内循环水运行温度高、系统总水量大,水质相对较差,该环境中不锈钢换热板的点蚀问题一直困扰化学运行人员。宁夏A供热管网设计最高温度130℃,循环水中氯离子浓度达到63.7mg/L,远高于CJJ/T 34《城镇供热管网设计标准》中规定的限值25mg/L,根据往年经验在供热过程中换热板存在较高的点蚀风险。本文通过现场情况调研,实验室模拟实验针对该热网水质特点制定了投加N型阻垢缓蚀剂,并严格控制循环水中氯离子浓度的策略。其中循环水中氯离子控制的期望值为小于70mg/L,当供水温度不超过110℃时,限制值小于90mg/L。在2022年~2023年供暖期间在现场应用该策略,取得了良好的应用效果,经检查316L换热板和旁路挂片均没有发生点蚀现象。

Since the temperature of circulating water in the heating network is high and the water quality is relatively poor,pitting corrosion of stainless steel heat exchange plate in this environment has been troubling the chemical operator a lot.The design temperature of heating pipe network in Ningxia is 130℃ and the concentration of chloride ion in circulating water reaches 63.7mg/L,which is much higher than the limit value of 25mg/L stipulated in CJJ/T 34 "Design Standard for Urban Heating Pipe Network".According to experience during previous years,there is a high pitting risk of heat exchange plates in the heating process.According to the analysis result of the water quality of the heat network,the anti-pitting strategy of the heat exchange plate was formulated in this paper.The strategy is adding N-type antiscale and inhibitor,strictly controlling the chloride ion concentration of the circulating water.The expected value of concentration of Cl-is set as less than 70mg/L.In addition,when the temperature of supply water is less than 110℃,the limiting value is set as less than 90mg/L.The strategy was applied in the field during the heating period from 2022~2023,and good application results were obtained,and no pitting phenomenon occurred in the 316L heat exchange plate and bypass mounting plate after inspection.