Study On Optimization Of Gas-solid Heat Transfer Performance And Resistance Characteristics In Vertical Tank For Sinter Waste Heat Recovery

The recovery and utilization of sinter waste heat resource is one of the effective ways to improve the energy utilization efficiency of the iron and steel industry.Based on the structure and process of coke dry quenching furnace,the vertical tank type sinter waste heat recovery system has been proposed as a new way and the focus direction for sinter waste heat recovery.The core of the research is the gas-solid heat transfer process and flow resistance characteristics in vertical tank.It is of great importance for determining the feasibility of the waste heat recovery technology with vertical tank.Therefore,this thesis focuses on the optimization design of the gas-solid heat transfer process and resistance characteristics in vertical tank.First,the sinter bed layer is regarded as porous media,and a steady state model based on the porous media model and the local thermal non-equilibrium is established for the numerical simulation of gas-solid heat transfer process.In order to fully evaluate the waste heat recovery performance of the waste heat recovery system,a new evaluation index,exergy destruction is used to characterize the irreversible heat loss and irreversible mechanical work loss in the gas-heat heat transfer process.It is adopted to analyze the impacts of air flow rate(1kg/s?1.75kg/s),sinter flow rate(1kg/s?1.6kg/s)and sinter particle diameter(15mm?45mm)on the gas-solid heat transfer performance.Then,BP neural network and multi-objective genetic algorithm are adopted to optimize the parameters of the vertical-tank waste heat recovery system,with heat transfer exergy destruction and flow exergy destruction as the optimization objectives.Therefore,the best combination of parameters for comprehensive performance has been obtained.The optimal solutions for heat transfer exergy destruction and flow exergy destruction are 251.16 W/m~3and 232.53 W/m~3,and the corresponding values of air flow rate?sinter flow rate and sinter particle diameter are 2.99 kg/s,0.61 kg/s,and 32.8 mm,when the initial ranges are set to0.3kg/s?3kg/s?0.3kg/s?3kg/s and 3mm?50mm,respectively.In order to explore the flow resistance characteristics in sinter bed layer,an experimental platform is set up to study the influences of air flow rate and particle size on the flow resistance.The experimental results show that the increase of air flow rate and the decrease of particle size of the packed particles can increase the flow resistance in the bed layer and increase the pressure drop.Then the experimental data is fitted to the corresponding resistance relational expression,f_v=174.38+1.22Re_m.