汽轮机初凝区腐蚀机理分析

AN ANALYSIS ON CORROSION PROCESS IN PRIMARY CONDENSATION ZONE OF STEAM TURBINE

从汽轮机初凝区的存在物质着手,通过电中性与物料平衡公式推导了在NH3、CO2、HCl、CH3COOH共存时其pH值的精确计算方程式,计算了4种物质的浓度在0.1 mg/L^0.5 mg/L之间变化时初凝水滴的pH值,由10幅图形表示计算结果,并分析了初凝区的腐蚀过程机理,及应该采取的措施.

The occurence of acid corrosion phenomena in low-pressure cylinder of steam turbine is much more frequent than before. Some investigations show that the corrosion is resulted from acidic gas （CO2,HCl,CH3COOH）, which dissolves in nascent condensation drips. But alkaline gas（NH3） exists in steam also, so the pH value in nascent condensed drips is a key question which determines if the corrosion occurs. In order to understand the pH value how to change when NH3.CO2.HCl and CH3COOH coexist, the author has deduced a precision pH value calculating equation by electroneutrality and quality balance formula. The particular pH value in nascent condensed drips may be calculated as their concentration vary from 0.1 to 0.5 mg/L, the exact calculation results are illustrated in 10 graphics. Thereafter the corrosion process of the condensator can reasonably be interpreted and some measures for corrosion prevention are given.