Separation efficiency of recirculating cyclones in circulating fluidized bed combustions

摘要

By a small excentrical shift and a narrowing of the cyclone insert, the separation efficiency of recirculating cyclones in seven commercial circulating fluidized bed combustions with thermal power between 55 and 550MW has been improved. Owing tothis change the mass flow of circulating ash has been increased by 20 to 100%, its mean particle size has been decreased by 20 to 30%. This led to a distinct better performance of the boiler, e.g. to a higher heat transfer, a simplified handling of thevarious ashes in the circuit and a drastic reduction of sand.A special design of the usually short entrance duct between burner and cyclone aiming at higher solid fuel velocities serves the purpose of increasing the separation efficiency.