Ceramic fiber is a high-quality refractory insulation material. It has the function of fire resistance and heat insulation. This material is generally suitable for use in high temperature parts. Previously, it was only used in steam turbine cylinders and linings of boiler furnace walls in thermal power plants. Now in the selection of thermal insulation materials, ceramic fiber refractory products are used for the inner layer of the thermal insulation layer when the temperature exceeds 400 °C.
(1) Applied to steam turbine insulation
Since the surface temperature of the steam turbine cylinder body reaches 550 °C, the steam turbine thermal insulation is often selected, and the thickness of the thermal insulation layer generally reaches 200 mm for the upper cylinder and 250 mm for the lower cylinder. The construction adopts the paste method, the middle is fixed with a mesh, and the surface layer is covered with a wire mesh.
(2) Application of boiler furnace wall
The thickness of the thermal insulation layer of the furnace wall is generally 180~200mm, and the temperature of the hot surface is generally around 450℃. Therefore, the inner layer insulation adopts 40~50mm Aladdin ceramic fiber blanket, plus two to three layers of mineral wool products or foam asbestos products.
(3) Application of ceramic fiber cotton
Ceramic fiber wool can be mainly used for filling, and is used in thermal insulation of rigid beams of boilers, expansion joints and sealing and plugging parts.
(4) Application of high temperature pipeline insulation
It is applied to heat preservation of high temperature pipelines such as main steam and reheated steam (cold and hot sections). This part of the pipeline is insulated, and various composite structures with ceramic fibers as the core replace some and all calcium silicate products.
Five types of composite thermal insulation structures for high temperature pipelines
a. Ceramic fiber rock wool insulation structure: the inner layer of ceramic fiber blanket, the outer layer of rock wool insulation structure, and the composite insulation structure with a total thickness of 180~200mm.
b. Ceramic fiber calcium silicate thermal insulation structure: the inner layer of ceramic fiber blanket, the outer layer of calcium silicate shell, the thermal insulation structure with a total thickness of 180mm.
c. Ceramic fiber foam asbestos insulation structure: the inner layer of ceramic fiber blanket, the outer layer of foam asbestos, the total thickness of 180~200mm composite insulation structure.
d. Ceramic fiber glass wool insulation structure: the inner layer of ceramic fiber blanket, the outer layer of glass wool products, the total thickness of the insulation layer is 180mm.
e. Ceramic fiber fiber tube shell: all ceramic fibers are used, the total thickness is 160~180mm, and the thermal insulation structure is divided into two layers.
In short, at present, in addition to calcium silicate products, ceramic fiber materials are used for thermal insulation of high-temperature main steam, reheat steam and other pipelines.
