In the configuration of refractory materials for waste heat boilers, for the vertical furnace wall with full membrane water-cooled wall in the cooling chamber, a three-layer structure can generally be adopted: the lining wall is made of insulating concrete with a thickness of about 40mm; the middle wall is made of ceramic fiber insulation board with a thickness of about 120mm; the surface layer is a plastering layer with a thickness of about 20mm. The total thickness of the furnace wall is usually 180mm. For fully suspended structure boilers, in order to reduce the load of the suspension rod, the middle wall should use insulation materials with very small unit density, such as rock wool or foam ceramic fiber blanket products.
The total thickness of the furnace wall of the vertical furnace wall structure of the light tube water-cooled wall is generally determined according to the allowable heat loss, and the economy of the material used is also considered. The furnace chamber wall is usually 200mm thick. The first layer is a refractory material layer with a thickness of (40~50)mm, and alumina cement or silicate cement refractory concrete is commonly used. The second layer is generally an insulation layer with a thickness of (80~130) mm, usually made of perlite or vermiculite products, and the third layer is a sealing layer with a coating thickness of about 20 mm.
There are two types of sealing layers for pipe-laying furnace walls:
One is that for boilers with external protective plates, general plastering can be used;
The other is for boilers arranged outdoors and without external protective plates.
After the plastering coating is completed, asphalt paste or polyvinyl acetate glass cloth must be laid to protect the furnace wall and strengthen the sealing of the furnace wall.
When laying pipe furnace walls, the material formula must be strictly controlled and appropriate wire mesh must be used. Close attention should be paid to the connection between the meshes, the compression and leveling of the meshes, the connection between the meshes and the rigid beams and door holes, the filling of the connection seams, the repair of the surface and the construction of the plastering layer.
When laying door holes, first design and lay them according to the door hole layout diagram. In order to ensure reliable sealing, sealing covers are welded on the water-cooled walls of each door hole, and pins and steel bars are welded on the inner and outer walls of the sealing covers to tightly combine the refractory material concrete with the metal plate to prevent smoke from passing through them.
The pitch of the ceiling densely covered with water-cooled wall tubes is similar to that of the furnace, but considering the working conditions and the complexity of the furnace roof structure, the thickness of the furnace wall on the furnace roof should be greater than that of the straight wall. However, the furnace wall layer is the same as that of the straight wall, but the thickness of the insulation layer is appropriately increased. Due to manufacturing errors and the influence of various factors during installation, the ceiling pipes are often uneven, with large and small pitches, uneven surface of the row pipes, and the pipes are pulled apart due to pitch, so they must be processed in advance before pouring the refractory concrete on the furnace roof. Generally, flat steel is welded to the ceiling pipes at a pitch greater than the normal pitch to cover it. However, if it is a micro-positive pressure boiler, flat steel and round steel should be welded between the normal pitch tubes, and steel plates should be used to seal the through-wall pipes. Steel plates should be used to seal the ceiling and the front and side wall water-cooled wall tubes. These welding works should be carried out before the water pressure test. The pouring of the furnace roof pipe and furnace wall is the same as that of the furnace chamber.
