Guidelines for the Use of Castables for Circulating Fluidized Bed Boilers

Refractory castables for circulating fluidized furnaces are generally used at medium and low temperatures, and the operating temperature is within 600-1800 °C. So what kind of properties do refractory castables used in circulating fluidized furnaces need to have? The main overall properties of refractory castables are high-temperature resistance, wear resistance, high strength, heat preservation, thermal shock resistance, and other functions.

Circulating fluidized bed boiler is the clean coal combustion technology with the highest degree of industrialization. The circulating fluidized bed boiler adopts fluidized combustion, and its main structure includes two parts: the combustion chamber (including the dense-phase zone and the dilute-phase zone) and the circulating furnace (including the high-temperature gas-solid separator and the return system). The biggest difference from the bubbling fluidized bed combustion technology is that the operating wind speed is high, which strengthens the heterogeneous reaction process such as combustion and desulfurization, and the boiler capacity can be expanded to a large capacity acceptable to the power industry. At present, circulating fluidized bed boilers have been very It solves basic problems such as thermal, mechanical, and material science as well as engineering problems such as expansion, wear, and overtemperature, and becomes the first choice for the energy utilization of non-combustible solid fuels (such as coal gangue, oil shale, municipal garbage, sludge, and other wastes). advanced technology.

High-temperature resistance and wear resistance

There is no doubt about the high-temperature resistance. The furnace part of the boiler is directly in contact with the flame, the temperature is slightly higher, and there will be burning cinders for friction, so it is generally done. The parts used in this part All refractory castables need to have fire-resistant and wear-resistant properties. Corundum refractory castables are very suitable for this part. Its strength is extremely high, and its cutting refractoriness and wear resistance are first-class at medium and low temperatures.

Thermal shock resistance

Generally speaking, if the temperature of the furnace rises or falls instantly in a short period of time, the damage to the refractory castable is extremely large, and it is very easy to cause the inner lining to fall off and crack. Therefore, in response to this phenomenon, there is a special thermal shock-resistant refractory castable, which has higher strength, and its thermal shock resistance is much better than other refractory castables.

Insulation

In the refractory castables used in recirculating fluidized furnaces, the insulation layer is also a very important part. It can increase the temperature of the boiler and save energy. It is most suitable to use perlite light insulation castables or diatomite insulation castables. Their main feature is that the insulation performance is very good, and it is most suitable for use in the insulation layer.