A research group composed of Toyo Glass and Asahi Glass is working to come up with a new method of glass melting a using oxygen combustion and plasma which could greatly reduce production time.

This technology, called in-flight glass melting, is a New Energy and Development Organization (NEDO) project, involving a joint research group composed of the 2 above mentioned glass producers, as well as the Tokyo Institute of Technology and a National Institute for Materials Science. The project began in 2005 and will run for 8 years, terminating in 2013. The first 3 years were dedicated to preliminary research, while currently a test furnace is in operation.

With this technology, granulated raw glass materials on the order of 100-200 ㎛ is fed into a furnace with an oxygen combustion burner with a flame at about 3,000℃, and then to a plasma torch with a flame up to 10,000℃. The material melts in a moment and then turns into glass. The conventional glass kiln, for example in the case of plate glass, requires a melting time of about 5 days. This technology can reduce this to less than half a day.

The high temperature flame of plasma and oxygen forms a framework which directly exchanges heat with the raw material. The facility itself can be greatly downsized. As a result, the amount of energy needed to melt the glass raw material is 1/3 that of the conventional method, achieving an energy saving of about 66%. Along with this, the reduction of the initial cost of the construction of the kiln, and of waste material such as the heat resistant bricks can be anticipated.

The currently used glass melting technology is based on the Siemens method developed some 150 years ago in the 1860’s. The current production method involves a larger facility and is suitable for mass production.

Nevertheless, improvement of the heat exchange ratio is more or less approaching its limit. There are also the rising prices of energy sources such as natural gas and oil and the demands for CO2 reduction. There is also a change in the demand environment which now does not necessarily require mass production. With the way things have been going up to now, a way out of this situation just cannot be found. Because of this, the Japanese glass industry is not looking for a new, ground breaking production method.

Based on the 3 years of preliminary research, it was indeed found out that this type of glass melting could actually be brought into being. Right now, work is going on with 3 different test furnaces to develop a system.