Working Principle Of Float Glass Tank Furnace

Glass is a widely used inorganic non-metallic material with extensive application coverage. It can be applied in architecture, daily consumer goods, art, instruments and other sectors, featuring a great variety of types. Apart from commonly used tempered glass and patterned glass, there are also high-tech varieties such as optical glass and smart dimmable glass. In this article, we will elaborate on the working principle of float glass tank furnaces, with a special focus on defining what an all-electric glass melting furnace is.

 The working principle lies in the different specific gravities of the two liquids: the lighter one floats on top, while the heavier one settles at the bottom.

 Forming of float glass takes place in the tin bath. Homogenized molten glass continuously flows into the tin bath through the overflow spout and launder. The glass melt spreads over the liquid tin surface and drifts forward under the traction of drive rollers. Under a specified temperature regime, the glass is flattened and thinned by surface tension and gravity. After cooling, the glass ribbon is lifted by the transition roller table, exits the tin bath and enters the annealing lehr. It then undergoes cross-cutting, inspection and packaging. Thanks to this special forming process, float glass boasts superior quality, diverse product ranges, high output and long service cycles for production lines.

 It features smooth ripple-free surfaces and excellent light transmittance. Flexible size specifications can be customized to minimize cutting waste, and it serves as base material for various deep processing applications.

 All-electric glass melting furnace, also simply referred to as all-electric furnace or electric melting furnace. After it was discovered that glass at high temperatures is electrically conductive, electric energy could be utilized as a heat source for glass melting, which gave rise to the application of electric melting furnaces for glass production. Since then, electric melting furnaces have gradually replaced a portion of flame furnaces.

 Glass tank furnaces heated by surface flame boast a long history. Although numerous structural improvements have been made over long-term operation, they still suffer from prominent drawbacks, including low thermal efficiency, complicated furnace structure, huge overall size and harsh working conditions.

 Electric melting furnaces were formally put into commercial production in the late 1940s. Judging from practical operation results, electric melting furnaces have outstanding advantages, including high melting rate, simple structure, high degree of automation and favorable working environment.

 Its core working principle relies on electric energy as the heat source. Silicon carbide or molybdenum disilicide resistance heating elements are generally mounted on the side walls of the furnace chamber to provide indirect resistance radiant heating. Some pot furnaces for melting special glass adopt induction heating, which generates eddy currents within the furnace and molten glass for heating.For tank furnaces, the molten glass inside the furnace directly acts as the heating resistor. Multiple groups and layers of electrodes can be arranged at different vertical depths of the glass melt to heat the glass. The temperature regime is controlled by adjusting electric power consumption. With this technology, the temperature of the space above the glass surface remains very low (known as a cold crown). Therefore, energy is mostly consumed for glass melting and furnace wall heat dissipation. There is no heat loss carried away by flue gas, nor environmental pollution from flue gas emissions, resulting in high heat utilization efficiency. In addition, no combustion system or waste heat recovery system is required.All-electric melting furnaces support automatic control, requiring fewer operators and offering favorable working conditions, yet they consume large amounts of electricity. They are suitable for melting refractory glass, volatile glass and dark-colored glass. Large all-electric melting furnaces are capable of producing 150 tons of container glass per day.