联合循环机组停备用腐蚀干风联合保护技术应用分析

Application research of dry-air combined protection technology for lay-up corrosion of combined cycle unit

为适应燃气-蒸汽联合循环机组热力系统停备用腐蚀防护需求,根据试验机组热力系统特点设计了覆盖机组全部热力设备的干风联合保护系统,并复配了一种适合干风联合保护工艺的气相缓蚀剂,在试验机组上进行了39天的干风联合保护工艺腐蚀挂片试验,研究干风联合保护工艺及复配气相缓蚀剂的保护效果。试验结果表明:除凝汽器底部积水位置碳钢试片轻微腐蚀,其他位置试片基本无腐蚀;同余热烘干法相比,采用干风联合保护工艺后机组冷态启动冲洗用水量下降约50%,汽轮机冲转阶段凝结水和给水铁离子质量浓度平均值分别下降63.5%和23.7%,运行8 h后的凝结水和给水铁离子质量浓度平均值分别下降80.5%和79.0%。

In order to meet the requirement of lay-up corrosion protection for thermal system of gas-steam combined cycle units,a dry-air protection system covering all the thermal equipment of the unit was designed,according to the characteristics of the thermal system of the test unit.Moreover,a volatile corrosion inhibition suitable for dry-air combined protectionprocess was compounded,and the corrosion coupon test was carried out for 39 days in the test unit,to study the protective effect of the dry-air combined protection process and the compound gas-phase corrosion inhibitor.The test results show that,by the dry-air combined protection,only the carbon steel piece at the bottom of condense was slightly corroded,the steel pieces at other positions were basically non-corrosive.Compared with the waste heat drying method,the water consumption during cold start flushing decreased by about 50%,the average iron ion mass concentration of condensate water and feed water decreased by 63.5%and 23.7%respectively during the turbine start-up stage,and they decreased by 80.5%and 79.0%respectively after running for 8 hours.