Selection of Refractory Materials for Different Types of Boilers

Unshaped castables, refractory and wear-resistant castables, plastic, low cement castables, corundum castables, steel fiber refractory castables, lightweight castables, etc. are most commonly used in boiler linings.

The power generation boiler is composed of a combustion chamber, water-cooled tube wall, superheater, economizer, preheater, and steam drum. The temperature of the combustion chamber of the power generation boiler is about 1550°C. The combustion chamber is equipped with a steam-cooled wall in the high-temperature flue of the water-cooled pipe near the furnace wall, so the temperature in the furnace wall is not high. Generally, it does not exceed 900°C. In the case of a furnace wall with a membrane water wall structure, the temperature is only 500-600°C. or even lower.

If it is a chain furnace or a pulverized coal furnace, the operating temperature is about 1000 ° C, and if it is a fluidized bed boiler, the temperature is relatively high, and many pipes pass through the furnace wall. Therefore, the grade of refractory castables for the lining of fluidized bed boilers should be high.

If it is a light-duty furnace boiler, the working layer of the furnace lining is generally lined with clay refractory castables or clay refractory plastics, and the heat insulation layer is made of light castables for insulation, and is also laid with insulation boards or fiber cotton; To enhance the airtightness of the boiler lining, a sealing layer will be coated on the outer surface of the furnace skin. This saves heat and saves fuel.

The pulverized coal furnace is scoured by pulverized coal particles and airflow at the same time, poured with high-alumina and clay refractory castables, and the furnace top is tamped with high-alumina refractory plastics; in the case of serious abrasion of coal particles or serious dust-laden airflow, high-resistant refractory castables are used. Grinding castable, that is, silicon carbide refractory castable, is used as the lining of the working layer to increase its service life.

If the boiler uses refractory bricks, it is used in the return feeder of the circulating fluidized bed boiler, the economizer furnace wall, the mixed suffocation inner wall, the flue, the chimney lining, etc.;

Refractory and wear-resistant castables are mainly used for boiler cyclone separators, furnaces, dense phase areas, furnace outlets, water-cooled air chambers, slag coolers, feeders, and ignition ducts. High-alumina refractory castables are used for boiler smoke corners, air chambers, economizer guard plates, fire doors, and other parts; lightweight heat-insulating castables are used for boiler top and furnace wall insulation;

Wear-resistant plastic is easy to construct, fast to repair, high-strength and wear-resistant, has good thermal shock resistance, no cracks, and good sealing performance. Mainly used in the repair and partial tamping of fluidized bed boilers; micro-expansion refractory plastics have strong plasticity at room temperature, strong adhesion, high strength after natural drying, micro-expansion at high temperatures, high fire resistance, good sealing performance, and convenient construction; corrosion resistance Wear-resistant ramming material, with good thermal conductivity, is conducive to heat conduction, and is used in parts of circulating fluidized bed furnaces that require wear and corrosion resistance;

Of course, different furnace types and different sizes use different castables and refractory bricks. All are selected according to the needs of the equipment.