Experimental Study On Gas-Solid Heat Transfer Coefficient Of Layer In Vertical Tank For Recovering Sintering Waste Heat In Some Working Conditions

The waste heat recovery of sintering vertical tank that was put forward by imitating the technology of CDQ is an efficient way for recycling sintering waste heat,and 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.The gas-solid heat transfer coefficient in bed is the key index to characterize and measure the gas-solid heat transfer intensity in this study.Our past research process of gas-solid heat transfer coefficient was:Gas-solid heat transfer experimental bench of fixed bed was established.The gas-solid heat transfer coefficient of unit area of effective gas-solid heat exchange was studied based on the heat transfer process of fixed bed in vertical tank simulating the heat transfer process of moving bed.But that process has a deficiency that it brings a certain deviation to calculate effective heat transfer based on the unsteady heat transfer process of fixed bed simulating the steady heat transfer process of moving bed.And the difficulty for gas-solid heat transfer area to be precisely calculated and measured makes the experimental results unreliable.Based on that,this article intend to conduct research of the gas-solid heat transfer coefficient based on the model of moving bed in the view of the inside volume of packed bed in the vertical tank by building machine rational experimental bench(the inner diameter of cooling section is 250 mm)This experiment makes up for the deficiency of the previous research to a certain extent since the simplicity for bed volume to be accurately measured,and based on the model of moving bed.But this article only carried out the related research in several working conditions of different flow rate of cooling air,down speed of sinter and diameter of sinter because of the limitation of experimental conditions.In this article,the calculation formula of the average volumetric heat transfer coefficient based on the model of moving bed was deduced firstly.The necessary data was obtained on the experimental bench based on the model of moving bed in several working conditions,and then was used to calculate the volumetric heat transfer coefficient in different working conditions.The change tendency of gas-solid heat transfer coefficient with the influencing factors of different flow rate of cooling air,down speed of sinter and diameter of sinter was analyzed secondly.At last,the empirical gas-solid heat transfer coefficient correlations were established using the dimensional method.The main results were as follows:(1)The Nu number empirical correlation which reflecting average gas-solid heat transfer coefficient in sintering layer of moving bed with different flow rate of cooling air,down speed of sinter and diameter of sinter may be shown as follows,Nu=0.235Re0.379Pr0.417(vg/vs)-0.105The application range of experimental correlations:417 ? Re ? 1543,0.652 ?Pr? 0.679.(2)Cooling air volume,particles size and down speed are the major factors,which affect heat transfer coefficient in sintering 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 hv and vg can be defined by hv = 21.63dp-0.92vg0.09.The smaller particle size is,the bigger heat transfer coefficient is,and the relation between hv and dp can be defined by hv = 0.92vs0.66dp-0.29.The larger down speed is,the bigger heat transfer coefficient is,the relation between hv and vs can be defined by hv = 0.73vg0.69vs0.38.