The boiler includes combustion equipment, combustion chamber, furnace and heat release flue. The furnace lining of combustion chamber is usually made of refractory bricks. The closed combustion chamber built with refractory bricks is used for fuel combustion and insulates the flame and heating surfaces in the boiler from the outside. Therefore, refractory bricks are required to have heat resistance, heat insulation and sealing properties. High alumina bricks and clay refractory bricks are mostly used.

1. Furnace wall structure made of  refractory bricks

The furnace wall of industrial boiler with capacity less than 35t/h is mainly of heavy structure. The furnace wall is directly built on the boiler foundation. The furnace wall is composed of internal and external layers. The fire-resistant inner village wall is built with T-3 standard refractory bricks. The thermal insulation exterior wall is made of machine-made red bricks. In order to improve the thermal insulation performance, a thermal insulation layer of about 20mm is left between the refractory brick and the red brick. This is used to fill the insulation material. Or lay 16mm diatomite insulating refractory bricks in the middle.

The corners of the four walls of the red brick exterior wall are required to bite each other to form a whole. The outer wall is hooped with a light steel frame. Some exterior walls are not equipped with steel frames. It looks like an ordinary brick wall.

The thickness of furnace wall is 360~730mm. The inner layer is 116~232mm refractory brick. The outer layer is 240~480mm red brick. In the low temperature area of the boiler tail flue, when the flue gas temperature is lower than 500 ℃, all the furnace walls are built with red bricks.

2. Roof structure

The furnace top structure of industrial boiler is usually arched and suspended. The arch furnace roof is composed of the arch foot beam of the profile steel, the arch foot refractory brick, the wedge refractory brick and the insulation layer. The hanging furnace roof is composed of profile steel hanging beam, hanging device, hanging brick and insulation layer.