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