钢筋混凝土排烟冷却塔的腐蚀防护设计

Design of anti-corrosion of a reinforced concrete cooling tower with flue gas injection

"烟塔合一"技术使得热电厂排烟冷却塔内部环境的腐蚀性大大增强,从而给塔壁混凝土的耐久性性能带来了严峻挑战。针对排烟冷却塔内部特殊的腐蚀性环境条件进行了腐蚀防护设计,配制了单掺粉煤灰、复掺粉煤灰和硅灰、复掺粉煤灰、硅灰和丁苯胶乳以及对比普通混凝土等四种混凝土,并选择了三种成膜型有机防腐涂层。接下来对四类混凝土试件的早期收缩、开裂、强度、弹性模量等物理、力学性能以及有防腐涂层、无防腐涂层试件的碳化、氯离子侵蚀、硫酸盐腐蚀和酸液腐蚀等耐久性性能进行了试验研究。研究结果表明:复掺粉煤灰和硅灰的混凝土其物理、力学性能和综合耐久性性能在所配制的四种混凝土中最优,但是单凭混凝土材料自身仍不能满足烟塔内部严酷的侵蚀性环境条件要求,而在防腐涂层的辅助帮助下可以保障排烟冷却塔的使用寿命。

The technology of ＂natural draft cooling towers with flue gas injection＂makes the risk of corrosive environment attack to cooling towers of thermal power plant greatly increase, so as to give the durability of concrete wall serious challenges.Based on this special corrosive environment conditions in cooling tower, 4 kinds of concrete mixtures such as fly ash concrete, fly ash and silica flame concrete, fly ash, silica fume and styrene-butadiene latex concrete, and ordinary portland concrete for comparison were designed, and three organic anti-corrosion coatings were selected.Then, experiments of concrete early age shrinkage, cracking, strength, elastic modulus and concrete carbonation, chloride ions diffusion, sulfate and acid solution corrosion were conducted to specimens with or without coatings.Results indi- cate that： the mixture of concrete with fly ash and silica fume was the best among 4 designed concrete mixtures from physical, mechanical properties and comprehensive durability performance ,but it still can＇t meet the harsh environment condition requirements inside cooling tower just by concrete material itself, and the composite protective system of fly ash and silica fume concrete with anti-corrosion coating can gaarantee the service life of cooling, tower.