How to Choose the Refractory Material of the Gasifier?

The refractory material of the gasifier can be divided into three parts: cone bottom, cylinder and vault. There is a certain expansion space between the vault and the furnace shell, so that the lining refractory bricks expand upward when the gasifier is running. It can be divided into several levels from inside to outside. Taking the cylindrical refractory material as an example, it is divided into four layers: fireproof refractory material layer, backing layer, heat insulation layer and compressible layer (the vault is the same as the bottom of the cone), and there is an expansion of 3~5mm between the three layers gap. Expansion in a convenient radial direction is unrestricted.

1. Refractory brick veneer

The working environment of refractory bricks is very harsh, and design units and users are very cautious about their structural design and material selection. Refractory surface layer: also known as hot face brick, is a high temperature resistant and corrosion resistant consumable layer. Typically, high chromium materials are required, which require high temperature chemical stability, high creep strength and thermal shock resistance. The thickness of the fire surface from the barrel to the CWS gasifier is about 230mm. Use 90 chrome aluminum zirconium bricks (high chrome bricks). The raw material of chrome-aluminum-zirconium brick is Cr203 fusion composite material, the content of Cr2O3 is more than 99% (volume density is more than 5.1g/cm3), and superfine powder is added. After mixing and molding, it is fired in a high-temperature shuttle kiln. The product has the advantages of high bulk density (greater than 4.25g/cm3), low porosity (less than 16%), high temperature resistance (greater than 120Mpa), low content of impurities such as iron oxide and silicon oxide, and good heat resistance. Stable energy, temperature resistance and creep, etc. all meet the requirements of gasifier refractories on the fire surface, so 90 chrome aluminum zirconium bricks are ideal products for gasifier fire surface refractories.

2. Backing layer refractory brick

Its main function is insulation, but it can be used as an inner lining for a short time when the refractory bricks are gone. The backing brick is mainly corundum brick. The thickness of the cylindrical refractory brick is about 200mm. Chromium corundum bricks are made of white corundum sand as aggregate and Cr2O3 as aggregate, which are mixed and sintered at high temperature. Refractory bricks are mainly used for the slag mouth of the slag gasifier, the fire surface of the carbon black reactor, and the backing brick of the coal-water slurry gasifier.

3. Insulation layer

The insulation needs to have good insulation to keep the metal enclosure within a reasonable temperature range while minimizing heat loss. Alumina hollow ball bricks are usually used. The thickness of the cylindrical refractory brick is about 110mm. Alumina hollow ball insulation refractory bricks/castables are mainly used for the bottom layer of slag hydrocarbon furnaces, carbon black reactors, and insulation layers of coal slurry furnaces.

4. Compressible layer

It can be compressed or recovered within a certain temperature range, thereby reducing the effect of radial thermal expansion stress on the shell. The thickness is about 15-20mm. Commonly used FBX1900 cement is a dry mixture of mineral fibers and no binder, contains effective rust inhibitors, but has no corrosive effect. It can be applied with trowel or spray gun during construction.

In order to strengthen the integrity of the lining, a combination of hoop and longitudinal bricks is required to prevent the flow of high temperature gas between the refractory bricks and to ensure the pressure shell of the refractory bricks and the backing refractory bricks. In order to improve the integrity of the furnace lining, it is required that the perimeter of bricks and vertical bricks should be firmly combined with bricks.

How to choose refractory materials for coal gasifier? I believe you can get a general idea of chrome-aluminum-zirconium bricks (high chrome bricks) for gasifiers, backing layers of corundum or chrome corundum refractory products, and hollow sphere insulation refractory bricks for insulation. If you have any other questions, please contact us. Xinhongji Refractory will provide you with a full range of refractory solutions.