Alternative Treatment Technologies

Flameless Thermal Oxidation—Thermatrix, Inc.

Flameless Thermal Oxidizers (FTO) are used to treat VOCs and chlorinated VOC (CVOC) off-gases by converting them to carbon dioxide, water and hydrogen chloride. The typical temperature of operation is about 1400 to 1700 ^oF (760 to 930 ^oC), hotter than typical catalytic oxidizers, but cooler than direct flame oxidation units. The heat for reaction is supplied by either supplemental natural gas addition (Figure 1) or electrical heating (Figure 2). The packed-bed reactor is typically filled with saddle- and spherical-shaped inert ceramic pieces. A uniform thermal reaction zone is generated in a ceramic bed. (See figure below.) The mass of the bed acts to absorb heat to suppress flames on the one hand, and to recover and release heat to cooler incoming SVE off-gases. The heat recovery reduces the fuel requirements to treat the waste gas stream and the packed bed of ceramic matrix materials mixes the gases uniformly. The units commonly operate with a large excess of oxygen to complete the oxidation reactions and to minimize formation of products of incomplete combustion such as carbon monoxide (CO). The technology has provided DREs up to 99.9999% for hydrocarbons and in excess of 99.99% for CVOCs, with production of extremely low NO_x (typically < 2ppm_v) and CO (below the limits of detection) formation. This technology operates over a wide range of flow rates (e.g. 1 to 6500 scfm), with low pressure drops, typically less than 3 inches of water.

Figure 1. Figure illustrating FTO unit with bottom feed vapor inlet and supplemental gaseous fuel addition without heat recovery. Adapted from Thermatrix case study, "Using flameless thermal oxidation for the safe, efficient destruction of phosgene."

Figure 2. Illustrating FTO unit with electrical heating to bring bed to operating temperature.

The technology was demonstrated on SVE vapors at the Department of Energy Savannah River site (Figure 3). For more detailed information or to view a report on an actual field application of this technique, please see FTORprt.