The furnace lining of cracking furnace has high requirements for refractory and thermal insulation materials, which need to have good air tightness and low thermal conductivity. Therefore, the furnace wall of cracking furnace of large ethylene cracking unit adopts light brick structure in the gas flow scouring area of burner, and other parts adopt refractory fiber and fiber module structure with good thermal insulation performance.
Due to the different operating conditions of each part, the refractory insulation materials used are also different. The materials used in cracking furnace lining can be roughly divided into insulation board, insulation refractory brick, refractory brick, ceramic fiber felt, ceramic fiber module, insulation castable, ceramic plate, etc. During the construction of cracking furnace lining, according to its structure, it can be divided into four parts: radiation chamber, transition section, convection section, flue and chimney. The specific configuration of refractory insulation materials for each part is as follows:
The radiation chamber is the heating reaction part of light hydrocarbon cracking medium, the furnace temperature is 1260 ℃, and oil and gas burners are set on both sides of the wall and at the bottom. The refractory and thermal insulation materials used at the furnace bottom, side wall/end wall and furnace top of the radiation chamber are different.
1) The furnace bottom is mainly made of insulating board, insulating refractory bricks, refractory bricks, etc.
2) The side wall/end wall adopts ceramic fiber felt, insulation board, fire-resistant insulation brick, fiber module, hook, hook fixing plate and fiber module anchor nails.
3) The furnace roof mainly adopts ceramic fiber felt, fiber module and fiber module anchor nails.
The side wall/end wall are installed with fiber modules, which are the same as the furnace wall of the radiation chamber. The modules at the profiled parts are installed with specially designed modules; The bottom lining structure is the same as the furnace bottom of radiation section. Materials required include ceramic fiber felt, insulation board, fire-resistant insulation brick, fiber module and fiber module anchor nail.
The side wall panel shall be prefabricated with fire-resistant castable on the ground with a thickness of 200mm; The 100mm thick insulation board is used as the backing, the end pipe plate lining has been completed, and the elbow box lining structure is 50mm thick (2 layers of 25mm) fiber blanket paving. The materials needed for the side wall include ceramic fiber board, castable, "Y" shaped anchor nails, and "V" shaped anchor nails. Anchors and ceramic fiber felt are required for elbow boxes.
4.Flue and chimney
Chimney and flue: the lining structure is 50mm thick refractory castable. Anchors and insulating castables are required.