Simulation Of Heavy Cylinder During Induction Heating Process And Experimental Study On The Heat Treatment Process

The heavy cylinder is the key part of the equipemnt of nuclear power,petrochemical hydrogenation reactor and coal liquefaction.With the development of the energy industry structure to the direction of low-carbon economy and clean energy,the quality requirements of nuclear power,petrochemical,aerospace and other areas for heavy cylinder is more and more strict.The heat treatment of heavy cylinder is usually carried out in the bogie hearth resistance furnace or flame furnace,which has low heating efficiency,high energy consumption and serious environmental pollution,and it can not meet the requirements of the development of modern industry.The induction heating technology can overcome the shortcomings above,which has many advantages such as high heating speed,high efficiency and no smoke.It is the trend of China’s industrial development and conform to the concept of energy saving and environmental protection.In this paper,the design of induction heating device,simulation during induction heating process and rapid heat treatment process of heavy cylinder are studied.First of all,the multi field coupling mathematical model of electromagnetic field,temperature field,stress field and structure field in the numerical simulation during heat treatment process of heavy cylinder was established,and the convective heat transfer coefficient and the radiant heat transfer coefficient and the spray cooling heat transfer coefficient during heating process and cooling process were calculated.Secondly,the phase transformation kinetics of austenite during continuous heating in2.25Cr1Mo0.25 V steel was studied.The dilatometric curves of the steel with different heating rate form 0.02℃/s to 10℃/s were measured.The J-M-A model was used to analyze the experimental data,and the parameters of the model were determined.The value of the activation energy of austenite transformation,the J-M-A exponent n,and the pre-exponential factor lnk0 are 479.8 kJ/mol,1.0782,and 45.6 respectively.Thirdly,the induction heating furnace of heavy cylinder was designed,and the induction heating process was simulated based on the finite element software.Considering the problem of corner effect during induction heating,three solutions were proposed.Thethird solution,by welding heat treatment ring in the end of the heavy cylinder and also adding magnetic conductor in the end of the coil,not only the corner effect is removed,but also the overall heating effect is better.The temperature field and thermal stress during the heating process of heavy cylinder with different heating methods including rectangular coil induction heating and conventional resistance furnace heating and spiral coil induction heating were researched.The simulation results show that when the rectangular coil inductor is used for heating,the heating efficiency is the highest,and the heating effect is better,meanwhile the thermal stress is acceptable for the heavy cylinder material.Finally,The physical simulation of the traditional heat treatment process and the heat treatment process based on induction heating were carried out,and the grain evolution and mechanical properties at center part of the heavy cylinder during the heat treatment process were studied.The physical simulation results show that the grain grade at the center part of heavy cylinder reached 7 grade with induction heating process,which is similar to the traditional heat treatment process,and the mechanical properties of the heavy cylinder can meet the application requirements.Therefore,the feasibility of the heat treatment process of heavy cylinder based on induction heating was verified.