Application of Lightweight Acid Resistant Castable in Chimney

The traditional masonry method of chimney lining is to use acid-resistant cement and acid-resistant bricks for masonry. Nowadays, the proportion of pouring and masonry using light acid-resistant castables is constantly increasing.

However, in the masonry mode of acid-resistant brick masonry, the problem of full horizontal and vertical joints of bricks will make the airtightness of the masonry poor, and the heat insulation castable of the heat insulation layer will become damp, which will cause the heat insulation performance to decline. The breakage of heat-insulating castables and the loose combination of bricks and bricks will cause corrosive fumes to penetrate the masonry and insulation layer and corrode the outer cylinder wall.

It is very inconvenient to construct the chimney with heat-insulating castables and lining bricks. Practical problems such as the installation of heat-insulated castables, the treatment of gaps between bricks, and moisture-proof measures seriously affect the chimney’s years of use.

If the heat-insulating castable and the lining of the anti-corrosion brick masonry are combined into one, light or ultra-light acid-resistant castables with strong corrosion resistance, good heat insulation, and high strength are used to make lightweight castables by pouring. High-quality acid-resistant castable lining, heat insulation performance, and anti-corrosion performance are combined, and the overall air tightness has been greatly improved.

Due to the sulfur dioxide in the flue gas in the chimney, there is water in the flue and the chimney to form dilute sulfuric acid. The acid will corrode the acid-resistant castable. Aluminate cement cannot be used as a binder for light acid-resistant castables. Salt cement It will cause the lining castable to crack and break. Therefore, the acid-resistant castable for chimney lining should be made of water glass as binder and aluminate as cement, which will be seriously damaged under the action of sulfuric acid.

Lightweight acid-resistant castables are mainly composed of raw materials and curing agents. The curing agent is ammonium phosphate or ammonium chloride or sodium fluorosilicate. The initial solidification time of the acid-resistant castable is 40 minutes. It is poured and rammed into the formwork, and the initial setting is 2 hours. After 24 hours, the mold is demoulded, and then it is naturally dried. Because the light acid-resistant castable has good sulfuric acid corrosion resistance, it can fully meet the anti-corrosion requirements of the chimney for the lining material.

The integral casting of light acid-resistant castables can make the inner lining integrated with good airtightness, and the volume is light, which also reduces the weight pressure of the chimney.