HEAT TRANSFER OF AN L-SHAPE SUSPENDED SURFACE IN A SUPERCRITICAL CFB OCTAGONAL FURNACE

摘要

A well understanding of the influence of shape and the variation in location on the surface on suspended surfaces is very important to the safety and efficiency of boiler operation, especially for a supercritical CFB boiler.This work conducted heat transfer tests of L-shape suspended surfaces in a CFB cold test rig, which is a part of the development of a 1000MW supercritical CFB octagonal boiler.The L-shape suspended surface was heated by silicone rubber heaters, on which thermocouples densely distributed.Local heat transfer coefficient in each part was obtained based on energy balance, which is lowest at the top and highest in protrusion (L-shape area) at the end.A higher surface average heat transfer coefficient was measured when the heat transfer probe was set facing to the cyclone entrance than it was set between two cyclones.Under the same test conditions, heat transfer coefficient measured on the riser wall is lower than those on the suspended surfaces.The experiments showed that heat transfer coefficient increases with solids suspension density.