The glass tank kiln heated by flame surface has a long history. Although many structural improvements have been made during long-term use, there are still serious drawbacks such as low thermal efficiency, complex kiln structure, large volume, and harsh working environment. Glass is an electrical conductor at high temperatures, and the alkali metal sodium and potassium ions contained in molten glass have conductivity. When current passes through, Joule heat is generated. If the heat is large enough, it can be used to melt glass, that is, using an electric melting furnace to melt glass. With the continuous improvement and development of furnace design and electrodes, this electric melting method has been widely used.
The fully electric melting furnace has outstanding advantages in terms of usage effect, manifested as: simple furnace structure, small footprint, stable control and easy operation, reduced scattering and volatilization of certain expensive oxides in raw materials, low noise, reduced impact on the environment, stable melting process and improved product quality, which are difficult to compare with fuel furnaces.
The main principle of an electric melting furnace is to use electrical energy as the heat source. Generally, silicon carbide or molybdenum disilicide resistance heating elements are installed on the side walls, bottom oblique inserts, and furnace top of the kiln for indirect resistance radiation heating. Some crucible furnaces used for melting special glass adopt induction heating method, relying on eddy currents induced in the furnace and glass liquid for heating. The tank kiln directly uses the glass liquid inside the kiln as a heating resistor. Multiple sets and layers of electrodes can be arranged at different depths of the glass liquid to generate heat, and the temperature system can be controlled by adjusting the power consumption. When using this method, the temperature in the space above the glass liquid level is very low (known as the cold furnace top), so the energy is basically consumed in the melting of glass and the heat dissipation of the kiln wall, without the loss of heat carried away by the flue gas and the pollution to the environment caused by the emission of flue gas. The heat utilization rate is high, and there is no need to set up combustion systems and waste heat recovery systems. The full battery kiln can be automatically controlled, requires fewer management personnel, has good working conditions, but the disadvantage is that it consumes a large amount of electricity resources. Suitable for melting refractory glass, volatile glass, and dark glass. The production capacity of large battery kilns for bottle and jar glass reaches 150 tons per day.
Post time: Aug-22-2024