Oxy-fuel Furnaces

Oxy-fuel melting involves the replacement of the combustion air with oxygen (>90 % purity). The technique can be used with either natural gas or oil as the fuel, although the use of gas is more common. The technique potentially involves on-site energy savings, because it is not necessary to heat the atmospheric nitrogen to the temperature of the flames. Less combustion air has to be heated and therefore less energy is lost with the furnace waste gases (IPTS/EC 2013, p. 226). The energy savings of converting to an oxy-fuel furnace depend on the energy use of the current furnace, use of electric boosting, air leakage, glass type, and cullet use (Worrell et al., 2008. p.64). Moreover, the indirect energy – the efficiency of the waste gas heat recovery system (recuperator, regenerator, etc.) and the energy required to produce the oxygen (can be between 0.4 – 1 kWh/Nm3) – related to oxy-fuel systems need to be taken into consideration (IPTS EC, 2013. p. 227). Besides reducing energy consumption oxy-fuel burning is a very effective method for reducing NOx emissions.

Virtually in all segments of the glass industry, 100% oxy-fuel combustion technology has been successfully demonstrated. Oxy-fuel technology also offer other advantages including increased productivity (15-20%), noise reduction, reduced melting times, and glass quality improvements due to smaller variations in the product. Disadvantages may include increased refractory wear, which may affect the product quality by increasing silica corrosion at the crown of the furnace, and decreased furnace life (or increased refractory costs), oxygen production costs, and potential problems related to conversions from regenerative furnaces (Worrell et al., 2008. p.64-65).

Development Status Products
Commercial
Glass

Oxy-fuel FurnacesCosts & Benefits

Parent Process: Melting and Refining
Energy Savings Potential

On-site energy savings can be greater than 50 % when small, thermally inefficient furnaces are converted to oxy-fuel firing.
For a medium-sized recuperative furnace with no specialised energy saving measures, standard levels of insulation, and using only internal cullet, the energy use with oxy-fuel melting would be in the region of 20 – 50 % lower (IPTS/EC, 2013. p. 231).

Even for large efficient regenerative furnaces, savings would be between 5 and 20% (Worrell et al., 2008. p.64)

EU flag A container glass manufacturer in Germany was able to reduce energy consumption from 5.02 MJ/kg to 3.02 MJ/kg (including energy consumption for oxygen generation) and realized energy savings of 35% by installing an oxy-fuel furnace with preheater (Worrell et al., 2008. p.65). 

CO2 Emission Reduction Potential
Costs

The capital costs of a new oxy-fuel furnace are around 20% lower compared to recuperative furnaces, and 30-40% lower compared to regenerative furnaces. The costs of the on-site oxygen plant are about 10% of the capital costs of the plant. Oxy-fuel furnaces also benefit from reduced costs for flue gas treatment (Worrell et al., 2008. p.64).

However, the necessity to install extra durable refractory material (high duty silica crowns may increase the capital costs by €300 000 to 400 000 and use of fused cast materials may increase the costs by €4–5 million (IPTS/EC, 2013. p. 236). Operation costs will increase.

Oxy-fuel Furnaces Publications

Page Number: 

64

Oxy-fuel Furnaces Reference Documents

Best Available Techniques (BAT) Reference Document for the Manufacture of Glass

As a reference of the EU Industrial Emissions Directive (2010/75 EU) this new version provides extensive information on Best Available Techniques (BATs) applicable to European Glass Manufacturing Industry for reducing environmental impact. The document is prepared by the  Institute for the Prospective Technological Studies of European Commission's Joint Research Center. 

Page Number: 

226-240