Durability Of Concrete Under Flue Gas Cooling Tower Corrosive Conditions

Cooling tower provides a new method for discharging flue gas for power plant. Flue gas contains SO2、NOx、HCl、HF and other corrosive components, therefore, the cooling tower and the water spray frame will be fast eroded in water vapor environment. The body design of cooling tower is still made of normal concrete in present structures. The corrosion of the inner wall of the exhaust cooling tower and the water spray frame is very serious. This article simulates the corrosive environment and temperature effect, makes a study on the durability of C40normal concrete, C40and C50high performance concrete, and reactive powder concrete through the simulating solution45℃soaking experiment and dry-wet cycle experiment. By comparison of durability evaluation, we can make a conclusion which kind of concrete has the best durability. The main conclusions are shown as follows:According to the simulating solution soaking experiment at45℃, the normal concrete and the high performance concrete have the same variation trend of concrete compressive strength, which can be divided into three stages:1) Initial strengthening phase2) Stationary phase3) Deterioration phase. However the reactive powder has the different one which only showed a very slow decreasing trend. The three kinds of concrete shared the same variations of neutral depth and mass loss ratio, which have an increasing trend with the time growth, but the reactive powder concrete has the smallest growth. It can be concluded that the reactive powder has the strongest anti-erosion ability under the exhaust cooling tower corrosive environment.According to the simulating solution dry-wet cycle experiment, the normal concrete and the high performance concrete shared the same variation trend of compressive strength. It can be divided into two stages:1) Initial strengthening phase2) Deterioration, while the reactive powder concrete only has the decreasing trend. And the compressive strength loss of reactive powder concrete is much smaller than that of the two other concrete. All the concrete change trends of neutral depth and mass loss ratio are same. But the reactive powder concrete has the smallest decreasing range. It can be concluded that the reactive has the best durability under the simulating dry-wet cycle environment.The corrosion of concrete was mainly caused by H+and SO42-in the simulating solution. SO42-reacts with hydrated calcium aluminate and Ca(OH)2, getting expanding ettringite and gypsum. By comparsion of the data from simulating solution soaking experiment and the dry-wet cycle experiment, the corrosive effect caused by the first experiment is more serious. It is can be concluded that the exhaust cooling tower concrete is probably damaged by long-term contact with the corrosive liquid.