Study On Heat Transfer Characteristics Of Powdered Activated Coke In Moving Bed

With the improvement of flue gas emission standards,the traditional flue gas desulfurization technology is largely limited by the bottlenecks of adsorbent sources,cost constraints and by-product high value technology;it is difficult to meet the current environmental requirements.Dry flue gas desulfurization technology with powdered activated coke possesses broad development prospects in the future desulfurization industry.High temperature shell-and-tube mobile bed is the most widely-used equipment for the regeneration process of powdered activated coke after desulfurization.The heat transfer efficiency of activated coke in the tube will directly affect the desulfurization process of the activated coke,and then affect the desulfurization efficiency of powdered activated coke desulfurization system.Therefore,it is significant to study the heat transfer characteristic of the in-tube flow of the powdered activated coke.In this work,the studies on the heat transfer characteristic of the in-tube flow of the powdered activated coke were conducted by using experimental and theoretical methods.Firstly,the heat transfer process of powdered activated coke moving bed is studied,and the heat transfer principle between air and activated coke particles is explored.The heat transfer between tube wall and particle side is analyzed,and the total heat transfer resistance model from tube wall to particle system is established.Secondly,the basic properties of one-step preparation of activated coke,including porestructure,physical properties of particles and thermos-physical properties were measured.Through the analysis of problems in experimental design,the experimental scheme was finally determined,and a steady-state experimental device was built up.Next,the total heat transfer coefficient,outside heat transfer coefficient and inside heat transfer coefficient of the moving bed heat exchanger were obtained based on the experimental data.The researches mainly focus on the inside heat transfer coefficient between tube wall and powdered activated coke.It is found that the heat transfer coefficient between tube wall and powdered activated coke is increased with the increases of the temperature and velocity of air inlet and the moving velocity of particles in the tube.Due to the reinforcement and transmission of disturbance in the vertical direction,the heat transfer coefficient of the upper tube section is higher than that of the lower pipe section.Additionally,the characteristic number relationship for the outside heat transfer between air and the tube wall was also obtained by the quantitative calculation and fitting analysis.At last,the heat transfer of powdered activated coke plunger moving in the tube was simulated by using Workbench software.The simulation results were compared with the experimental data.The key factors affecting the heat transfer coefficient of the actual coke flow inside the tube are explored.The intrinsic discipline of heat transfer of the actual coke flow inside the tube was better understood.The research results provide theoretical guidance for the design of powdered active coke moving bed heat exchanger.