Electromagnetic And Thermal Properties Analysis In Laminated Cores Of A Continuous Casting Tundish With Induction Heating

A tundish with induction heating can provide heat for the continuous casting,realizing the low superheat casting at a constant temperature,which is very important for improving the quality of the steel billets and steady operation.As the electromagnetic and thermal properties in the laminated cores made in our country is not stable,the electromagnetic devices in the steel corporations of our country,such as Baosteel and Fushun steel,are imported from foreign countries.However,there is none research about electromagnetic and thermal in laminated cores of a continuous casting tundish with induction heating so far.Therefore,this study is meaningful.The electromagnetic and thermal in laminated cores of a continuous casting tundish with induction is analyzed by numerical simulation in this paper.Basing on the working principles of the system and the finite element method,the math model solved by magnetic vector potential and electric scalar potential is created with the Maxwell equation,the electric field and magnetic field constitutive equations,continuity equation of electric current and Joule heat law.The 3-D magnetic flux parallel boundary condition and real constant are set to get the unique solution.Then a new physical model is created for the induction heating system,the iron core of which is divided into 2mm silicon steel sheets and 0.06mm insulating layers.As length and the width of the silicon steel sheets an insulating layers in the laminated core are 2515mm and 2327mm,the ratio of the length and the thickness is very large,so the meshing of the 201 silicon steel sheets are difficult to ensure 4 layers meshes in the thickness direction.Using the math model to solve this physical model by harmonic analysis type,the electromagnetic field and Joule heat distribution in the silicon steel sheets and the molten steel are computed accurately.Comparing with former models,this model can compute the eddy current in the silicon steel sheets accurately.Then the influences of the position of the coil,the shapes of the silicon steel sheets,the exciting current to the results of the induction heating are investigated by this model.The model is also used to analyze the electromagnetic field and Joule heat distribution in a channel tundish with induction heat.Using the sequential coupling method,the Joule heat is added to the energy conservation equation as a source term.The computation of the cooling of the induction heating system by the wind can be realized with finite volume method,so the temperature distribution of the silicon steel sheets as well as the temperature,pressure and flow field of the air can be analyzed.The research concluded:(1)One coil is hung in one side of the laminated cores is best in the four layouts,and the electrical efficiency of it is 90.34%.The closed silicon steel sheet is better than the other two shapes in electrical efficiency.The powers of any part or the total power in the tundish are proportional to the square of the exciting current,and the electrical efficiency has no relationship with the current.(2)There is obvious eddy current in the cross sections and the surfaces,and the eddy current in the four inner corners is larger than other position.The Joule heat in the silicon steel sheets becomes smaller as its distance to the surface becomes large.The Joule heat distribution is the same as the eddy current distribution in the silicon steel sheets.The magnetic spread along the silicon steel sheet,and the magnetic flux density in the four inner corners is larger than other place.The magnetic flux density becomes smaller as it flows because of the eddy current.(3)When the coil is loaded AC exciting current,a induction current loop would be formed in the tundish.The current density in the channels is far larger than that in the receiving chamber and discharging chamber.Because of the proximity effect,the current in the side closed to the coil is larger than the other side.The periodical variation of the induction current generates magnetic field,and the magnetic in or around the channel is circular and nonuniform.The interaction of the magnetic and the induction current generates the off-center electromagnetic force in the channels.The interaction of the induced current and the molten steel generates Joule heat,while 77.54%of the total Joule heat is generated in the channels.(4)The temperature of the laminated cores will be increase to 620K after 5.6h without ventilation cooling.When the laminated cores are cooled by air of 300K,and the volume flow rates are 3.61 m~3/s,4.1m~3/s,4.69m~3/s,the highest temperatures of the regions located outside the air duct are 352.46K,351.98K and 351.47K,while the highest temperatures located in the air duct are 344.97K,340.37K and 336.77K.The ventilation cooling making the temperature of the induction heater can be effectively controlled.