The temperature of the flue gas at the end of the power plant boiler is generally around 130°C. After the desulfurization device is installed (especially wet desulfurization), the temperature of the flue gas entering the chimney will generally drop to around 50°C. The flue gas after desulfurization contains a large amount of water vapor, unremoved sulfur dioxide and other corrosive media, which will corrode concrete or carbon steel materials and cause serious damage to the chimney over a long period of time. For this reason, the inner walls of concrete chimneys must be corrosion-resistant.