Low NOx Oxy-Gas Burner

The two largest problems facing high temperature combustion processes are the consumption of large quantities of fuel and the production of high levels of pollutants. The production of NOx is of particular concern in high temperature processes because NOx yield increases as combustion temperature increases. Both problems can be addressed for natural gas combustion by switching from air-gas to either oxygen enriched air-gas or oxygen-gas firing. Combustion with oxygen offers advantages of reduced energy costs, lower NOx and particulate emissions, and decreased capital and maintenance costs by eliminating the need for flue gas cleaning and heat recovery. Oxy-gas flames burn at a higher temperature, allowing energy savings through more efficient radiant heat transfer and higher energy availability. Low NOx levels result from the presence of a reduced amount of nitrogen in the flame. While oxy-gas firing for industrial processes such as glass melting is attractive and has been adopted commercially to some extent, optimization of the process promises large rewards in both energy savings and NOx reduction. The dominant mode of heat transfer to the load in a process such as glass making is by radiation. Radiative heat transfer is dependent upon both the temperature and emissivity of the heat source. At the high combustion temperatures of an oxygas or a high temperature air-gas flame, the combustion products are not luminous (low emissivity) which leads to low radiation, poor heat transfer to the batch, a high exit gas temperature, low process efficiency and production rate, high fuel consumption, and poor furnace efficiency. Process and energy efficiency increase for high temperature furnaces. Increasing flame luminosity by seeding the flame with soot particles has been shown to provide significant benefits to oxy-gas combustion. Although huge potential gains can be made, commercial application of this technology has not occurred due to the complexity and cost of coburning a source of soot particles with natural gas