General Burner Types

In oxy-burner testing, generally two types of measurements are involved (i) measurements inside flames and (ii) global measurements in the furnace. In-flame measurements include chemical composition, flame temperature profile, and optical properties. Global measurements include flame shape, emissions, heat flux, and measurements taken on the load. Figure 27.13 shows typical measurements and their locations in an oxy-pilot furnace. 

Spent Acid or Burning. Burners for spent acid or hydrogen sulfide are generally similar to those used for elemental sulfur. There are, however, a few critical differences. Special types of nozzles are required both for H2S, a gaseous fuel, and for the corrosive and viscous spent acids. In a few cases, spent acids maybe so viscous that only a spinning cup can satisfactorily atomize them. Because combustion of H2S is highly exothermic, carehil design is necessary to avoid excessive temperatures. 

The desired air—fuel volume ratio is usually seven or more, depending on the stoichiometry. Burners of this general type with many multiple ports are common for domestic furnaces, heaters, stoves, and for industrial use. The dame stabilizing ports in such burners are often round but may be slots of various shapes to conform to the heating task. 

If the substitute fuel is of the same general type, eg, propane for methane, the problem reduces to control of the primary equivalence ratio. For nonaspiring burners, ie, those in which the air and fuel suppHes are essentially independent, it is further reduced to control of the fuel dow, since the air dow usually constitutes most of the mass dow and this is fixed. For a given fuel supply pressure and fixed dow resistance of the feed system, the volume dow rate of the fuel is inversely proportional to. ypJ. The same total heat input rate or enthalpy dow to the dame simply requires satisfactory reproduction of the product of the lower heating value of the fuel and its dow rate, so that WI = l- / remains the same. WI is the Wobbe Index of the fuel gas, and... 

Fuel specifications from different sources may differ in test limits on sulfur, density, etc., but the same general categories are recognized worldwide kerosene-type vaporizing fuel, distillate (or gas ou ) for atomizing burners, and more viscous blends and residuals for commerce and heavy industry. Typical specifications are as follows. 

Vertical flares These are single-burner combusters generally oriented to fire upward. The discharge point is in an elevated position relative to the surrounding grade and/or nearby equipment. Three types of support methods are used for vertical flares ... 

Under the 1948 commercial standard CS 12-48, fuel oil No. 1 is defined as intended for vaporizing pot-type burners and other burners requiring this grade, whereas No. 2 is defined as for general purpose domestic heating for use in burners not requiring No. 1. The No. 1 fuel is therefore specified to have a low 10% point in the ASTM distillation to ensure quick starting, and a low end point and low carbon residue to ensure clean vaporization. 

Conceptually, there are two types of flame spread tests. The length of the specimen is generally much greater than the width and flame propagation is measured in the direction of the longest dimension. In the first type of flame spread tests, the specimen is exposed to a gas burner flame at one end. In the second type, the specimen is exposed to a radiant panel producing a heat flux that varies from one end of the specimen to the other. A pilot flame is used to ignite the specimen at the hot end. An example of each of the two types is described as follows. 

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