The main purpose of using wear-resistant refractory materials as lining for circulating fluidized bed boilers is to protect the steel shell of the furnace body from being eroded and worn by the burning materials.
The most commonly used linings for boilers are amorphous castables, refractory and wear-resistant castables, plastics, low cement castables, corundum castables, steel fiber refractory castables, lightweight castables, etc.
The power generation boiler consists 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℃. The combustion chamber is equipped with a steam-cooled wall in the high-temperature flue of the water-cooled tube near the furnace wall, so the temperature inside the furnace wall is not high. Generally, it does not exceed 900℃. If it is a furnace wall with a membrane water-cooled wall structure, the temperature is only 500-600℃. Even lower.
If it is a chain furnace or a pulverized coal furnace, the working temperature is around 1000℃. If it is a fluidized bed boiler, the temperature is higher and many pipes pass through the furnace wall. Therefore, the grade of refractory castables used for the lining of fluidized bed boilers should be high.
If it is a light furnace boiler, the working layer of the lining is generally lined with clay castables or clay refractory plastics, and the insulation layer is insulated with lightweight castables, and insulation boards or fiber cotton are also used for laying; some manufacturers will apply a sealing layer on the outer surface of the furnace skin to enhance the air tightness of the boiler lining. This is more heat-insulating and fuel-saving.
The pulverized coal furnace is flushed by pulverized coal particles and airflow at the same time, and is cast with high-aluminum and clay castables. The furnace top is rammed with high-aluminum refractory plastics; when the coal particles are worn or the dust-containing airflow is severely eroded, high-wear-resistant castables, that is, silicon carbide refractory castables, are used as the working layer lining to increase its service life.
If the boiler uses refractory bricks, it is used in the return device, economizer furnace wall, mixed suffocation inner wall, flue, chimney lining and other parts of the circulating fluidized bed boiler;
Refractory and wear-resistant castables are mainly used in the cyclone separator, furnace, dense phase area, furnace outlet, water-cooled air chamber, slag cooler, return device, ignition air duct, etc. of the boiler. High-aluminum castables are used in boiler smoke corners, wind chambers, economizer guard plates, fire doors and other parts; lightweight insulation castables are used for boiler tops and furnace wall insulation;
Wear-resistant plastics are easy to construct, quick to repair, high-strength wear-resistant, good thermal shock resistance, no cracks, and good sealing performance. Mainly used for repair and local 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 temperature, high refractoriness, good sealing performance, and convenient construction; corrosion-resistant and wear-resistant ramming materials have good thermal conductivity and are conducive to heat conduction. They are used in circulating fluidized bed furnaces that require wear and corrosion resistance; Of course, different furnace types and sizes use different refractory castables and refractory bricks. They are all selected according to the needs of the equipment.
