Study On Gas-Solid Heat Transfer Model In Vertical Tank For Recycling Sinter Waste Heat

The waste heat recovery of sinter vertical tank that was put forward by imitating the structure and process of CDQ is an efficient way for recycling sinter waste heat, one of the core issues was the heat transfer issue between sinter and the cooling air in vertical tank, which belonged to the gas-solid heat transfer issue in moving bed. In the methods of the current studying the gas-solid heat transfer issue in bed layer, the numerical calculation was one of the main research methods, and the establishment of gas-solid heat transfer model was the key to numerical calculation. Therefore, the gas-solid heat transfer model of vertical tank for recycling sinter waste heat was studied by imitating the gas-solid heat transfer theory of non-fluidized bed in the paper, which would lay a good foundation for the subsequent numerical calculations.Currently, the correlational studies of steady gas-solid heat transfer model in moving bed were only limited in CDQ and blast furnace, and the research or description of their energy equations was not sufficient; the correlational studies of gas-solid heat transfer model in sinter bed layer were all limited in the sintering cooler, and the gas-solid heat transfer process in sinter bed layer was unsteady-state process; while the above researches had three drawbacks, namely the voidage of bed layer was regarded as constant, the traditional Ergun formula was used to calculate bed layer resistance losses, and the universal empirical formula was used to calculate the gas solid heat transfer process in bed layer, which affected the accuracy of the calculation. Based on this, at first, measurement method and water-filling imaging method were used to determine the sinter particle shape factor and voidage distribution of sinter bed layer; Secondly, the two-energy equations of local non-equilibrium thermodynamics were introduced into the gas-solid heat transfer model of sinter vertical tank, and two-energy equations used to solve the gas-solid heat transfer process in sinter vertical tank were derived through theoretical analysis; Then, using the secondary development platform of FLUENT software, namely user-defined functions(UDF), the model parameters results of bed layer voidage distribution, resistance coefficient, gas-solid heat transfer coefficient were compiled into the gas-solid heat transfer model of vertical tank; Finally, based on the experimental results of hot moving bed, the effects of single and double energy equation, different sinter bed layer voidage distributions, different bed layer resistance coefficients, different gas-solid heat transfer coefficients on the accuracy of numerical results were studied quantitatively, thereby the basic parameters for solving the gas-solid heat transfer process in sinter vertical tank were confirmed.Based on the above research, the following conclusions are obtained.(1) The relationship between sinter particle shape factor and three-dimensional length is as follows (?)s=(b/a)0.6557(c/b)0.6771(2) The bed layer average voidage decreases with the increase of bed layer geometry factor, and eventually tends to constant. Bed layer voidage is the largest at the inner wall surface, and decays to the center of bed layer, voidage reaches minimum value in the center of bed layer.(3) The gas-solid heat transfer model of vertical tank is calculated, and based on experiment results, single condition contrast is analyzed. The results show that the calculation errors of dual energy equations compared to single energy equation, the radial voidage distribution of sinter bed layer compared to the voidage is constant, the sinter bed layer resistance coefficients compared to the traditional Ergun resistance coefficients, the gas-solid heat transfer coefficient in sinter bed layer compared to the traditional empirical formula, are all reduced.