STUDY OF IMMERSED HEAT-EXCHANGE SURFACE F OR HIGH-EFFICIENCY HEAT-RECOVERY FROM WIRE RIM TIRES IN A FLUIDIZED-BED BOILER

In an ICFB boiler, the fluidized bed is separated by a partition into the main combustion and the heat recovery chambers. The flows in these chambers are generated by using silica sand as the fluidizing medium. To determine the overall heat transfer coefficient (HTC) of the boile r's panel type immersed heat transfer tubes, combustion tests were per formed with wire rim tires. The overall HTC of a panel tube array was lower than that of a zigzag tube arrangement. In practice, the heat ab sorbed by the fins makes the coefficients of either type of tube array almost identical. The air flowrate in the circulating bed at the bott om of the heat recovery chamber can be changed to control the overall HTC to a value virtually identical with that of a zigzag tube array. T he combustion of wire rim tires leads to a buildup of wires in the zig zag array. hampering the transfer of heat. Yet, the panel type array s howed no buildup so that it was possible to maintain steady operation with this type of tube arrangement.