摘要:
The invention relates to a combined fluidized bed and pulverized coal combustion method and system. In the method, fluidizing air (4) is injected into a fluidized bed (2) situated in the bottom portion of the combustion chamber (3). Into the combustion chamber, to above the fluidized bed (2), is fed a mixture of pulverized coal and a carrier gas from a second set of fuel feed means (6) at a mass flow rate which is higher or at least substantially equal to the upper ignition limit of the mixture, and the mixture of the pulverized coal and the carrier gas at least by the fluidizing air (4), and at least a fraction of the fuel fed via the second set of fuel feed means (6) is combusted above the fluidized bed (2).
摘要:
Method for combusting pulverized fuels in a tangentially fired boiler and reducing emission of nitrogen oxides comprises steps of feeding a substantially air-deficient mixture of fuel and primary air through a fuel feeding pipe (1) tangentially into a furnace of the boiler in order to form a reducing flame (II) aNd blowing of at least one stream of combustion air into the furnace. The invEntion is based in that the stream of primary air and fuel is caused to recirculate and turbulate at the open end (2) of the fuel feeding pipe (1) by passing it through a flame holder (9) extending into the fuel feeding pipe (1), and the stream of combustion air is directed away from the primary air/fuel stream in order to prevent the combustion air to mix into the reducing flame (II).