Liquid Injection Incinerators

Liquid injection incinerators are applicable for pumpable liquid waste. These units (Figure 11.14.2) are usually simple, refractory-lined cylinders (either horizontally or vertically aligned) equipped with one or more waste burners. Liquid wastes are injected through the burner(s), atomized to fine droplets and burned in suspension. Burners, as well as separate injection nozzles, may be oriented for axial, radial or tangential firing. Improved use of combustion space and higher heat release rates can be achieved by using swirl or vortex burners, or designs involving tangential entry. A forced draft must be supplied to the combustion chamber for the necessary mixing and turbulence.

Good atomization is critical to achieving high destruction efficiency in liquid combustors. Nozzles have been developed to produce mists with mean particle diameters as low as 1 micron (/m), as compared to oil burners, which yield oil droplets in the 10 to 50 /m range. Atomization may be obtained by low pressure air or steam (25 to 100 psig), or mechanical (hydraulic) means using specially designed orifices (25 to 250 psig).

Vertical, downward-oriented liquid injection incinerators are preferred when wastes are high in inorganic salts and fusible ash content; horizontal units may be used with low ash waste. In the past, the typical capacity of liquid injection incinerators was 30 MM Btu/hr heat release. However, units as high as 210 MM Btu/hr are in operation.

Discharge to Quench or Waste Heat Recovery

Discharge to Quench or Waste Heat Recovery

Gas Residence Time

FIG. 11.14.2 Typical liquid injection combustion chamber. (Reprinted, with permission, from Dempsey and Oppelt 1993.)

Gas Residence Time

FIG. 11.14.2 Typical liquid injection combustion chamber. (Reprinted, with permission, from Dempsey and Oppelt 1993.)

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