Introduction to the change of thermal efficiency of circulating fluidized bed boiler

　　The circulating fluidized bed boiler has a large load variation rate. When the load deviates far from the economic load (75-85% of the rated load), it will cause a significant change in the thermal efficiency of the boiler. When the load is below the economic load, increase the load and increase the thermal efficiency. Above the economic load, the thermal efficiency will decrease as the load increases. The circulating fluidized bed boiler is favorable for peak load regulation and can be operated at low load, but the lower the load, the farther it deviates from the economic load.

　　The thermal efficiency drops a lot because when the load increases, the fuel supply increases accordingly, and the exhaust gas loss increases under the condition that the excess air coefficient in the furnace remains unchanged; The heat transfer efficiency is improved, and the carbon content of the flue gas and fly ash overflow slag and cold slag is reduced, that is, the loss of fly ash and overflow ash is reduced. At this time, the heat taken away by the cold slag is also reduced accordingly. The reduction value of the heat loss of fly ash, overflow ash and cold slag is greater than the increase value of the smoke exhaust loss, so the thermal efficiency increases and the operation exceeds the economic load.

　　The increase of fuel supply will shorten the average residence time of the particulate fuel in the bed, increase the precipitation of fine particles, and increase the loss of fly ash and overflow ash. In addition, the loss of exhaust gas temperature will also increase, so the thermal efficiency will decrease.