海水冷却器硫酸盐还原菌腐蚀状况与对策

大连石化公司濒临大海 ,淡水资源匮乏 ,其冷却器大部分采用海水。随着海水污染程度加大以及季节性工艺操作条件的变化 ,导致海水冷却器在冬春季节腐蚀严重、频繁出现泄漏。从三催化车间冷却器内提取海水、管板粘泥、海泥和已腐蚀双相钢管内腐蚀产物进行微生物培养 ,证实管内海水中硫酸盐还原菌含量为2 5个 /mL ;海泥中为 990个 /g ;粘泥中为 6 75个 /g ;腐蚀产物冲洗水中为 2 0 0 0个 /mL。管束腐蚀主要为硫酸盐还原菌所致 ,同时也与季节性变化和工艺操作有关。改善取水环境、加强电解海水处理 ,在冬、春冷却水流速低的季节加强反冲洗等措施可使腐蚀问题得到缓解。

Corrosion of Sulfate Reduction Bacteria in Sea Water Cooler and Countermeasures

Most of the coolers in Dalian Petrochemical Company have to use sea water as the cooling media because of the shortage of fresh water supply due to its plant location at sea side. With increasing pollution of sea water and seasonal variation of process operating conditions, the sea water coolers are subject to severe corrosion in spring and autumn, resulting in frequently leaks. The culturing of microbe of sea water, sludge from tube sheets, sea mud and corrosion product of duplex steel tubes finds 25/mL of the sulfate reduction bacteria in sea water, 990/mL in sea mud, 675/mL in sludge and 2000/mL in flush water of corrosion product. The tube corrosion is mainly caused by sulfate reduction bacteria and affected by changing of seasons and operating conditions. The corrosion problems can be mitigated by improving water intake conditions, strengthening sea water treatment and reinforcing back flush in winter and spring when cooling water flow velocity is low.