RESPONSE OF CFB BOILER TO STEP-CHANGE IN FUEL TYPE

ABSTRACT Circulating fluidised bed combustors have demonstrated that they can burn a wide variety of fuel efficiently and in an environmentally acceptable manner. This paper describes tests in the Studsvik 2.5 MWth CFB prototype to determine the response of the boiler (effect on boiler gaseous emissions, furnace pressure drop, solids recirculation rate, etc) when it was subject to instantaneous changes in fuel type. The two fuels fired were wood pellets and coal. During the fuel changes the furnace temperature was kept constant by automatic control of the primary solids recirculation rate. This control worked efficiently and the fuel changes were smooth. It is concluded that the Studsvik ‘variable inventory’ CFB is well suited to rapid switching of fuel type.