Method of and Arrangement for Feeding Fuel Into a Circulating Fluidized Bed Boiler

摘要

A method of feeding at least one of light, fine, volatile and moist fuel into a furnace of a circulating fluidized bed boiler. Fuel is introduced into the furnace and is combusted in the presence of a fluidized bed material to form flue gases. The fluidized bed material is circulated both inside the furnace in an internal circulation in which bed material returns along walls of the furnace down to the bottom of the furnace, and outside the furnace in an external circulation that includes at least a solids separator arranged in flow communication with the furnace. Bed material is separated from the flue gases in the separator. The flue gases are removed from the separator for further treatment. The separated bed material is returned to the furnace. Circulating bed material from at least the internal circulation flowing down along the furnace walls to a return flow is collected, and the return flow is introduced in a consolidated form into communication with the fuel being introduced in the furnace, so that the bed material return flow and the fuel flow are mixed together and flow downwards in the furnace. This increases the residence time of the fuel in the furnace.