Parallel Pass Reheat Control
The backpass contains two parallel gas passes, one containing the reheater and the other the superheater. Biasing dampers at the backpass outlet are used to adjust the gas flow over the reheater as needed to control RH steam temperature to the desired level as a function of load. This design has been proven on Foster Wheeler pulverized coal-fired boilers in sizes up to 900 MWe.
Duct Burners
Duct burners, tiring oil and/or natural gas, are used to preheat the primary air stream which in turn preheats the bed material to the temperature needed for solid fuel combustion. This preheating method maximizes the efficiency of bed preheating and so minimizes the amount of start-up fuel required.
Water-Cooled Air Plenum
The air plenum under the grid at the base of the furnace distributes primary air to the fluidizing nozzles in the furnace floor. Foster Wheeler uses a water-cooled plenum, formed from tubing which then forms the furnace walls. The plenum is designed for high temperature gas so that boiler start-up time is minimized.
Fluidizing Nozzles
Directional or non-directional fluidizing nozzles arc available. These proven nozzle designs provide for low pressure drop, minimal back-sifting and minimal pluggage.
Steam-Cooled Cyclone
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