Effect Of Coil Parameters Of Medium Frequency Electromagnetic Induction Heating On Temperature Distribution Of Dehydrogenation After Welding Of Large Nuclear Power Workpieces

This paper mainly studies the induction heating process for dehydrogenation after surfacing of the cylinder of the core makeup tank(CMT)and the tube sheet of evaporator of nuclear power.According to the shape of the workpiece which is heated by the cylinder and the tube sheet,the induction coil structure is designed and the influence of the structure parameters and power supply parameters of induction coil on the temperature distribution of dehydrogenation induction heating after surfacing of both the cylinder and tube sheet was studied.Based on the basic principles of electromagnetics and heat transfer,the mathematical models of electromagnetic field and temperature field in induction heating are analyzed.After that the Electromagnetic-Thermal coupling model of induction heating for large nuclear power workpiecesis established,and then the temperature distribution of the workpieces heated by induction heating is predicted by using ANSYS software.Firstly,the temperature field of induction heating after surfacing welding for the inner wall of large nuclear power cylinder is simulated and analyzed.According to the structural characteristics of the cylinder,the C-type induction coil is designed.The influence of the number of turns of induction coil,the heating distance between coil and workpiece,current and frequency on the temperature distribution of cylinder are studied.Results show that when the current,frequency and coil turns are larger,the induction heating effect of the cylinder is better.The temperature distribution is more uniform when the temperature difference between the inner and outer walls of the cylinder is smaller.The distance between the induction coil and the barrel is closer,the he temperature is higher of the cylinder,but the temperature distribution is basically the same,When the current is 215 A,the frequency is 10 kHz,the coil turns are 7 turns and the distance between the coil and the workpiece is 25 mm,the induction heating temperature of the cylinder can meet the technological requirements of post-weld heat treatment.Finally,through the experimental verification method found that the simulated temperature is the same as the experimental temperature trend,and there is a temperature difference of 5?.Secondly,the numerical analysis of the induction heating temperature field after the large-area surfacing welding of the tube sheet is carried out.According to the structural characteristics of the tube sheet,the induction coil structure of the tube sheet induction heating is designed.The temperature distribution of tube sheet after induction heating is studied in three cases: side induction coil and bottom induction coil,side induction coil and bottom induction coil.The results show that,when the current is 145 A,the frequency is 10 kHz,the side coil is 4 turns and the bottom coil is 5 turns,the temperature field distribution after induction heating meets the heating process requirements.Finally,through the experimental verification method,the tube plate simulation temperature and the experimental temperature trend are the same,and the size has a reasonable temperature difference of about 8?.