凝汽器铜管氨腐蚀的研究

Experimental Study on Corrosion of Condenser Copper Tubes in Ammonia

研究了影响凝汽器铜管氨腐蚀的因素与规律,以确定防止凝汽器氨腐蚀的途径。将HAl772A铜管管样在10种氨浓度、两种溶解氧浓度的溶液中浸泡45d,测定溶液的溶解氧变化情况,用失重法、原子吸收法测定铜管管样腐蚀速率;在6种温度、两种溶解氧、4种氨浓度条件下研究温度对铜管腐蚀速率的影响。氨液浓度小于800mg/L时,铜管氨腐蚀轻微,氨液浓度为800～1000mg/L时铜管腐蚀速率明显增大,且随氨液浓度的增大而增加;开口状态下铜管腐蚀速率比闭口时大,温度升高时同一氨液浓度下铜管腐蚀速率增大。凝汽器铜管氨腐蚀主要影响因素是溶解氧与氨液浓度,氨液浓度超过800mg/L后,腐蚀速率随氨浓度、氧含量、温度的增加而增大;用失重法与原子吸收法测定铜管腐蚀速率基本一致。

The factors affecting the corrosion of condensor copper tubes in ammonia and the relevant rules were investigated. Thus the HAl77-2A copper tube samples were soaked in ammonia solutions of different ammonia concentrations (500～20 000 mg/L) and different dissolved O_2 concentrations (open and close state) at room temperature for 45 d, and the variation in the dissolved oxygen of the ammonia solution was measured. At the same time, the corrosion rate of the copper tube samples was determined by corrosion mass loss measuring and atomic absorption spectroscopic analysis. Moreover, the influence of temperature on the corrosion behavior of the copper tube samples was investigated at different temperatures (20～45 ℃), different dissolved O_2 concentrations (open and close state), and different ammonia concentrations as well. It was found that the copper tube samples had a slight corrosion at an ammonia concentration below 800 mg/L. The corrosion rate of the copper tube samples significantly increased with increasing ammonia concentration within 800～1 000 mg/L and with increasing temperature at a fixed ammonia concentration as well. Besides, they recorded a larger corrosion rate in open system than in closed system. The corrosion behavior of the condenser copper tube was largely dependent on the concentrations of the dissolved O_2 and ammonia. The corrosion rate increased with increasing concentration of the ammonia and dissolved oxygen and water temperature as well. Moreover, the corrosion rate determined by corrosion mass loss was similar to that determined by atomic absorption spectroscopy.