Content area
Full Text
Do you think there is nothing new in the field of gas generators? Think again. An old friend, the exothermic gas generator, is making a comeback by combining smart controls and innovative design features. Let's learn more.
Once the dominant leader in supplying a source of nitrogen for purging/blanketing gas and for producing a furnace atmosphere with up to 12% hydrogen, in recent years, exothermic gas generators have taken a back seat to non-generated gases and gas mixtures. However, with some new wrinkles and with rising costs, it may he time once again to investigate this often forgotten technology.
Applications, sizes and types
Exothermic gas generators produce either a lean or rich atmosphere composition (Table 1) depending on the chosen air-to-gas ratio. Today, generator capacities vary from 500 to 50,000 cfh and larger. Depending on the application, the gas produced is cooled either by direct water spray into the gas stream or indirectly through a shell and tube heat exchanger. Outlet pressures of approximately 0.5 to 2.0 psig are common, but output gas pressure of up to 150 psig (and higher) can be designed.
Although hydrocarbon gases such as natural gas, propane and butane are the most common, virtually any combustible fuel can be used including coke-oven gas, MAP gas, and liquid fuels (for lean atmosphere only), such as kerosene, alcohols, and fuel oil. Conversions between gases require only changing a burner and flowmeters. Exothermic gas can be used in a variety of industries including heat treating, melting, petrochemical and food. Table 2 shows typical use of exothermic gas in heat treatment and other thermal processes.
The use...