Gas burner

Gas is burned in many industrial furnaces because of its cleanliness, ease of control of furnace atmosphere, ability to produce a long slow burning flame with uniform and gradual energy liberation, and ease of temperature regulation. Natural gas is used for steam generation in gas-producing areas and in areas served by natural-gas transmission lines where coal is not available at a competitive price. It is also burned extensively in coal- or oil-fired units during the summer months in districts served by natural-gas pipe lines, at which time the absence of the domestic heating load creates a temporary surplus of natural gas. By-product gas such as blast-furnace gas may be available at the steel mills for steam generation. Because of the variable or seasonal supply of gaseous fuels, combination burners have been developed to permit the simultaneous burning of the available gas together with pulverized coal or oil in an amount sufficient to produce the required steam.

When a molecule of combustible gas is mixed with the oxygen necessary for its combustion at a temperature above the ignition temperature, combustion is practically instantaneous. For steam generation, where a short flame is desired in order to reduce the required furnace volume, the burner should provide for rapid and thorough mixing of the fuel and air in the correct proportions for good combustion. For such applications, a good burner is primarily a proportioner and

mixing device. In industrial furnaces where long “lazy” flames are desired, slow and gradual mixing of the air and fuel in the furnace is necessary.

In the burner the gas, under pressure in the supply line, enters the furnace through a burner port and induces a flow of air through the port. Mixing is poor, and a fairly long flame results. The flame can be shortened by use of the ring burner, in which the gas flows through an annular ring and induces air flow both around and within the annulus of gas.