Experimental research of heat transfer uniformity for fluidized bed heat exchangers in a 300 MW CFB boiler

Abstract

In order to investigate the heat transfer uniformity of fluidized bed heat exchangers (FBHEs), a series of experimental tests were carried out in a commercial 300 MW CFB boiler. The test results indicate that there is a good linear correspondence between the FBHEs conical valve openings and circulating ash flow rate, the average heat transfer coefficient of different heat exchangers takes on a monotonically increasing trend with the increase of the boiler loads. Moreover, there is a non-uniform heat transfer process between the different measuring points under the same load as well as the different loads for the same measuring points, the heat absorption proportion of two FBHEs (71# and 72#) on the left side is larger than that of two FBHEs (73# and 74#) on the right side of the furnace, there is a non-uniform heat transfer phenomena in the symmetrical arrangement of four FBHEs, the heating surface arrangement in the FBHEs must be adjusted from snake tube perpendicular to the ash flow direction to parallel to ash flow direction, the test results can provide a good reference for the optimized design and operation of 600 MW supercritical CFB boiler with the FBHEs in the future.