Experimental Study On Heat Transfer Coefficient Of Layer In Vertical Tank For Recovering Sinter Waste Heat

The way of vertical cooling tank for sintering heat recovery is put forward, based on the structure and craft of furnace in CDQ. Two key problems to be solved urgently are the gas-solid heat transfer characteristic and flow in the sinter layer. The comprehensive heat transfer coefficient in layer is one of the key factors to influence the heat transfer between the sinter and the cooling air, and then affects the structural and operational parameters of vertical tank. The traditional experimental correlations formula about gas-solid heat transfer coefficient in packed bed are difficult to adopt to the way of vertical cooling tank for sintering heat recovery. The related date of heat transfer process in the sinter layer are tested in different cases by experiments in this paper, the experimental correlation formula of heat transfer coefficient in sinter layer is derived by applying dimensional analysis, and then the main factors and the influence rules affecting heat transfer coefficient were. This research not only gets the correlations formula of gas-solid heat transfer coefficient in sinter layer but also points out the direction for strengthening gas-solid heat transfer coefficient in tank, simultaneous lays foundation for numerical calculation of gas-solid heat transfer process in sinter layer.In essence, the air-solid heat transfer in sinter layer of fixed bed may be regard as a kind of gas-solid counter moving bed, the temperature in sinter layer in the tank decreases from drop to down. Adapting fixed bed to simulate moving bed, the principle as followed, the heat transfer process in fixed bed is unsteady, and the temperature in sinter layer is gradually reduced as time goes by. The height of sinter layer in fixed bed is much smaller than the height used in the production in future, so supposed the temperature in sinter layer of fixed bed is uniform, then regard sinter layer of fixed bed as an ’infinitesimal’ space of moving bed, the temperature in this ’infinitesimal’ space can be known as uniform(the distribution of temperature in whole bed is approximate in ladder). Therefore, adapted the distribution of temperature under different time in the fixed bed to simulate the distribution of temperature in different’infinitesimal’ spaces in moving bed. Some conclusions were drawn as follows:(1) The Nu number empirical correlation which reflecting gas-solid heat transfer coefficient in sinter layer of fixed bed may be shown as follows,Scope of Application:0.687≤Pr≤0.703,450≤Re≤1200(2) The scope of application of heat transfer coefficient in sinter layer is25-55W/(m-K), heat transfer coefficient in the tank decrease gradually from top to down.(3) Cooling air volume, particles size, bed height and edge effect are the major factors, which affect heat transfer coefficient in sinter layer. The factors may be adjusted in the production scope in future. The bigger cooling air volume is, the bigger heat transfer coefficient is, and the relation between h and v can be defined by h=15.27v0.82T0.12. The smaller particle size is, the bigger heat transfer coefficient is, and the relation between h and d can be defined by h=0.83d-0.53T0.09. The higher bed height is, the bigger heat transfer coefficient is, the relation between h and H can be defined by h=231H0.24T0.21. In addition,heat transfer coefficient at the edge is greater than which is in the center.