Experiment Research Of Gas-solid Heat Transfer Coefficient And Exergy Transfer Coefficient In Sinter Vertical Moving Bed

Sinter waste heat recovery in vertical tank,proposed by our research group with the intellectual property rights,is an efficient technology to recovery waste heat.Compared with existing indexes,its generated energy is increased by 100%per ton of sinter.One of key problems is the heat transfer between sinter and cooling air in vertical tank,and its essence is gas-solid countercurrent heat transfer among large particles of moving bed layer in vertical tank.The gas-solid heat transfer coefficient and exergy transfer coefficient describe the process of heat transfer in vertical tank more precisely.Based on first law of thermodynamics,heat transfer coefficient describes the intensity of gas-solid heat transfer quantificationally.The notion of gas-solid exergy transfer coefficient,proposed by our research group,can describe the intensity of gas-solid exergy transfer quantificationally,which compensates for the deficiency of heat transfer coefficient combining with first and second law of thermodynamics.Related to the gas-solid heat transfer coefficient and exergy transfer coefficient in sintering bed are only conducted in our research group nowadays.At the beginning,researches of heat transfer coefficient and exergy transfer coefficient were based on fixed bed.There are certain deviations compared with practical moving bed.At the same time,there are also some deviations due to the difficulty of obtaining the gas-solid heat transfer area.In the following studies,heat transfer coefficient was based on moving bed experiments and bed volume.Ascribing to deficiencies in experimental facility,such as serious air leakage and uneven heating in sinter,experimental results are lower reliable.Based on this,in this paper the machine rational experimental device was set up,improved the discharge structure and changed heating method from kiln heating to coal gas heating;meanwhile,it was supplemented by experimental verification of pilot vertical tank for sinter waste heat recovery.Based on the experimental data,experimental correlation of sinter gas-solid heat transfer coefficient was fitted out in moving bed layer,inferred out gas-solid exergy transfer coefficient,and analyzed exergy transfer characteristic in pilot vertical tank for sinter waste heat recovery.The papers is aimed at indicating the direction and way for intensifying gas-solid heat transfer in tank and a high level usage of energy.It also provides appropriate experimental correlations for the gas-solid heat transfer numerical calculation in moving bed layer with sinter particles.The main research contents,conclusions and innovations are as follows.(1)It embodies experimental correlation of gas-solid heat transfer Nusselt number in the moving bed layer with sinter particles as follows.Nuv= 0.296 Re0.762 Pr0.33 scope of application:362 ? Re? 2389,0.676 ? Pr? 0.701.(2)The factors,including sinter particle size,quantity of cooling air flow rate,height of cooling zone and sinter mass flow rate,impact gas-solid heat transfer coefficient in the moving bed layer with sinter particles.And ascribed to the decrease of sinter particle size,the increase of cooling air flow rate,cooling section height and sinter mass flow rate,the gas-solid heat transfer coefficient increases.The sinter particle size and cooling air flow rate have a great effect on it,and the height of cooling zone and sinter mass flow rate are less influential.(3)It embodies expression of gas-solid exergy transfer Nusselt number as follows.It includes temperature Nusselt and press Nusselt as follows.scope of application:362 ? Re? 23 89,0.676 ? Pr? 0.701.(4)Gas-solid exergy transfer process is mainly caused by temperature;by contrast,internal pressure loss is less influential to entire process.Increasing the cooling air flow rate and sinter mass flow rate can increase gas-solid heat transfer coefficient and then it can intensify gas-solid heat transfer process.There are optimum values of cooling air flow rate and sinter mass flow rate,which can make exergy efficiency the highest.