Oxygen for glass furnaces (oxy-fuel combustion)

What oxy-fuel firing changes

The 2001 paper, published in the ACEEE conference proceedings for that year, notes that glass furnaces have traditionally burned natural gas or oil with preheated air. The oxy-fuel furnace substitutes oxygen for air in the combustion process, which significantly reduces NOx emissions and the fuel consumption required per ton of glass produced, and also reduces other exhaust gases. A 2007 paper at the ACEEE Summer Study on Energy Efficiency in Industry, by D. Paul Mehta and Amol Nayak of Bradley University, states that with proper furnace design and burner selection a NOx reduction of 50 to 70% compared with a regenerator furnace is achievable.

Choosing the oxygen supply

The 2001 paper names three primary methods to supply oxygen to glass furnaces: adsorption systems, merchant liquid oxygen delivery and cryogenic production. The choice depends on capital and operating costs unique to each installation, including consumption volume, electricity costs and proximity to existing oxygen production plants. Its findings, as of 2001:

• Cryogenic production allows higher purity but is equipment-intensive, and generally needs too much capital to be cost-effective unless the furnace produces more than 200 tons of glass per day (TPD); beyond 200 TPD, recently commercialised small cryogenic plants are often the best option.
• For glass industry oxygen purity requirements, vacuum pressure swing adsorption (VPSA) is generally the low-cost choice up to the 120 TPD range.
• Merchant liquid supplies are not economic for furnaces producing at least 10 TPD, which the paper says is the vast majority of glass plants.
• VPSA, introduced in 1991, is a point-of-use supply that makes 90 to 95% purity oxygen more economical and convenient. The first commercial VPSA plant was installed to supply oxygen on site, replacing the liquid oxygen delivered for the startup and operation of an early demonstration furnace.
• Of the three adsorption systems, the paper rated VPSA the most energy-efficient and cost-effective compared with vacuum swing adsorption (VSA) and pressure swing adsorption (PSA).

ULTRAOX VSA

The ULTRAOX VSA datasheet lists industrial furnaces among the applications of this Ultra Controlo industrial oxygen plant; it does not name glass furnaces specifically. ULTRAOX VSA delivers 75% to 95% oxygen at 50 kPa, reaches higher pressures with an additional oxygen booster supplied on demand, is supplied on a skid or in a container, and can replace cryogenic systems with liquid oxygen tanks or work as the main source of supply. Its seven models deliver 18 to 240 m³/h at 93% oxygen and 22 to 288 m³/h at 90%.