What Is a Glass Furnace?

Glass is an electrical conductor at high temperatures. Molten glass contains alkali metal sodium and potassium ions, which have conductive properties. When the current passes, Joule heat is generated. If the heat is large enough, it can be used to melt glass. This is called "glass electrofusion".

Glass electric furnace

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Glass is an electrical conductor at high temperatures. Molten glass contains alkali metal sodium and potassium ions, which have conductive properties. When the current passes, Joule heat is generated. If the heat is large enough, it can be used to melt glass. This is called "glass electrofusion".

Chinese name

Glass electric furnace

Foreign name

Glass electric furnace

Types of

Electric conductor

Contains

Alkali metal sodium, potassium ion

In 1902, Voelker was granted a basic patent that uses the heat generated by glass currents to melt glass. With the continuous improvement and development of furnace design and electrodes, this electrofusion method has been widely used. From 1920 to 1925, Raeder of Norway successfully used graphite electrodes to achieve full electric melting of glass. In 1925, Corneljus in Sweden used this electric furnace to produce amber and green glass. The electric melting furnace adopts a thin layer feeding method, and the batch material floats on the surface of the glass liquid. When the electric furnace is put into production, it is equipped with a temporary furnace cover. When the glass level covers the electrode, the furnace cover is removed. The electrode used is a large iron block. Because the iron electrode colors the glass, this melting furnace can only be used to melt colored glass, which has a good effect. At that time, it could reach 1.40 kWh / kg glass, so this operation was feasible in areas with low electricity prices. Some of these electric melting furnaces have been running until recent years. In the period from 1932 to 1940, Ferguson used "T" shaped electric melting furnaces to actively conduct research on electric melting.

During the Second World War, Switzerland's Borel did a lot of research and development in electrofusion to solve the problem of fuel shortage. Bolle's work was a success and was promoted by the French company St. Gobain, which also did practical work on electrofusion.

After World War II, people began to be interested in molybdenum electrodes. The electrode system designed by Penberthy used molybdenum rods. In 1952, the glass industry began to widely use electric flux and all-electric melting. The other is the plate-shaped molybdenum electrode proposed by British Gell and Hann in 1956.

In the past 20 years, glass electric melting has been rapidly promoted. About half of the bottle and glass melting furnaces in the United States are equipped with electric flux, and are still increasing, from the early 300kW to the current 800-1500kW. The development trend has not stopped, and now there is super electric flux.

At present, there are at least 100 all-electric melting furnaces in the world ranging from 4t / d to 120t / d. Each year, several seats are added, and the scale is expanding in both electro-assisted and all-electric melting.

In the past 20 years, a new concept, "hybrid melting", has received increasing attention. The concept is: firstly, about half of the glass is produced inside the molten batch by heating, and then the other half of the glass is produced by heating the fuel above the batch. The goal is to reduce the total cost of heat required per ton of glass while still maintaining the same quality as electric melting furnace glass.

Another major new development is the use of electric melting furnaces to melt lead crystalline glass for machines and manual production of high-quality tableware. About 1964, the rod-shaped tin oxide electrode was put into industrial application, and a good electrical contact system was invented for this electrode, which established a good foundation for lead glass electrofusion.

The third development in the past 20 years is the promotion of electric heating channels.

The fourth new development is the use of a "mini-electric melting furnace" for the production of high-quality glass with a melting capacity as low as 10 kg / h.

The fifth development in the past 20 years is increasing attention to the control of environmental pollution. In this respect, the electrofusion process is of great significance.

The electric melting method has many outstanding advantages. The thermal efficiency can be as high as 80% to 85%, saving energy, no pollution, eliminating pollution, and improving working conditions. The molten glass has uniform composition and high product quality. The production process facilitates automation. Therefore, glass electric melting has been rapidly promoted abroad.

In developed countries, glass electrofusion has been widely used in the production of optical glass, borosilicate glass, lead glass, fluoride glass, bottle glass and fiber glass, and the process has matured.

According to 1979 estimates by Russel Burman, nearly half of the world's glass melting furnaces will use electrofusion technology.

In the early 1960s, China's glass fiber industry began to study the electrofusion process from the research of wire drawing and platinum furnace replacement. It has been decades. At present, electric flux is used in the flame tank kiln for manufacturing flat glass, special instrument glass, and vessel glass. The power consumption is not much, but it has a good effect on improving product quality, increasing output and improving labor conditions. It has a promising future. broad. It is expected that in the next few decades, many flame tank kilns will widely adopt electric fluxing. With the development of China's electric power industry, the application of all-electric fusion technology will also increase year by year.

Glass electric melting has great advantages compared with traditional flame heating melting furnaces. Since the glass liquid is directly used as a Joule heating effect conductor, the thermal efficiency of glass electrofusion is much higher than that of a flame melting furnace. The thermal efficiency of the glass electric melting furnace with a load of more than 60t is greater than 80%. In addition, the furnace structure of the electric melting furnace is simple, covers a small area, is stable and easy to operate, and reduces the scattering and volatilization of some expensive oxides in the raw materials, reduces noise and improves environmental pollution, stabilizes the melting process and improves products. Quality, etc. These are incomparable with fuel stoves.

China has abundant hydropower resources and new nuclear power plants, which provide the energy foundation for the promotion and application of glass electrofusion technology. Therefore, glass electric melting is one of the development directions in the future.

working principle:

Glass conducts electricity at high temperature and generates Joule heat for glass melting

The electrodes are electrically heated. The electrodes include tin electrodes, molybdenum electrodes, and graphite electrodes. Different electrodes are used for different glass qualities and types.

Knowledge required for operation:

1.Glass technology

2. Basic electrical knowledge

Precautions:

1. Must be equipped with a generator

2. Factors affecting the life of the kiln: kiln's masonry materials, electrodes, powder composition, and operator's operation