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

The vertical tank heat recovery is a effective method of recovery of waste heat of sinter, in which one of the key issues is gas-solid heat transfer in particle moving bed. Heat transfer progress is exergy transfer and conversion progress essentially; exergy transfer coefficient quantitatively describes the intensity of exergy transfer between sinter surface and cooling air. At present, the study on exergy transfer coefficient in particle moving bed is in its infancy, and there is no paper about exergy transfer coefficient in sinter bed.In essence, the gas-solid heat transfer inside the tank material layer is a moving bed gas-solid countercurrent steady heat transfer, the temperature inside the tank material layer gradually decline from top to bottom. The principle of using fixed bed to simulate moving bed is as follows:The heat transfer progress in fixed bed is nonsteady-state, the material layer temperature gradually decreases with time passing; It can be assumed that the temperature of material layer in entire fixed bed is uniform because the fixed bed material layer height is much lower than the height for production in the future, then regard the material layer in fixed bed as a "infinitesimal" space in moving bed, in which the temperature is uniform(the temperature distribution of whole material layer in tank is a stepped approximately); therefore, the temperature distribution at different time in fixed bed can be used to simulate the temperature distribution at different "infinitesimal" space(material layer) in tank.Based on this, this paper first introduced the concept of exergy transfer coefficient in convection heat exchanger and gas-solid heat transfer in fixed bed into sintering heat recovery tank, and deduced the exergy transfer coefficient formula in sintering moving bed. Then measured the relevant data of tank material layer transfer process under typical conditions in homemade experimental platform, to study the main factors of exergy transfer coefficient and its influence law. And finally fit the experimental correlation of exergy transfer coefficient in material layer through regression analysis on dimensionless equations by dimensional analysis. This study not only obtains the experimental correlation of gas-solid exergy transfer coefficient in material layer, but also indicates the direction of gas-solid heat transfer enhancement inside the tank, and lays a foundation for the numerical calculation of gas-solid heat transfer in bed.Some conclusion were dawn as follows:(1)The experimental correlation reflected exergy transfer coefficient in material layer is:Application range:107.2≤Re≤8764.1,0.673≤Pr≤0.714,17.456≤Eu≤201.02.(2)The average physical exergy transfer coefficient increases with the rising of sinter temperature, and decreases from top to down of material layer in tank, which varies-56～33W/(m2·K).(3)Sinter superficial velocity, sinter particle size, material layer height, and tank diameter are the main factors affecting exergy transfer coefficient. The exergy transfer coefficient increases with the increasing of flow, the reducing of sinter particle diameter, the raising of material layer, and the increasing of tank diameter.