초록 ▼

A thermal treatment process employs an indirectly fired rotary kiln in which matrix material contaminated with organic substances such as dioxins, PCBs, PAHs, fuel oils, and the like is heated as the material is advanced through the kiln to cause components of the organics to be released as vapor. P

A thermal treatment process employs an indirectly fired rotary kiln in which matrix material contaminated with organic substances such as dioxins, PCBs, PAHs, fuel oils, and the like is heated as the material is advanced through the kiln to cause components of the organics to be released as vapor. Purge gas of low oxygen content is conducted through the kiln at a relatively low velocity of from about 0.5 ft./sec. to about 10 ft./sec. to gently sweep the vaporized components of the organic substances from the kiln and to minimize the entrainment of solid particulates, and to produce an off gas mixture including the vaporized components. The off gas is conditioned after removal from the kiln to render it acceptable for discharge to the atmosphere. The oxygen concentration in the kiln is maintained at a sufficiently low level to substantially prevent combustion of the vaporized organic components in the kiln.

대표청구항 ▼

A thermal treatment process for matrix material contaminated with organic substances employing an elongate rotary kiln having a feed end and a discharge end and a wall defining an interior space extending longitudinally therethrough from said feed end of said kiln to said discharge end of said kiln,

A thermal treatment process for matrix material contaminated with organic substances employing an elongate rotary kiln having a feed end and a discharge end and a wall defining an interior space extending longitudinally therethrough from said feed end of said kiln to said discharge end of said kiln, an external surface of said kiln adjacent said interior space and separated therefrom by the wall thereof, means for rotating the kiln about its longitudinal axis with said kiln being configured to advance the matrix material through the kiln from the feed end to the discharge end as the kiln is rotated by said means for rotating, said process comprising: employing said means for rotating to rotate the kiln about its longitudinal axis; feeding the matrix material into the feed end of the kiln so that the material is advanced by the rotating kiln from the feed end toward the discharge end; combusting a hydrocarbon fuel to produce high temperature combustion gases having a relatively low oxygen concentration of below about 2%; contacting the high temperature combustion gases with the external surface of the rotating kiln so that heat is indirectly transferred to the interior space of the kiln through the wall of the kiln from the external surface thereof to thereby heat the matrix material advancing through the kiln in an indirect manner and cause components of the organic substances and water therein to be released from the material as vapor; conducting at least a portion of the low oxygen content combustion gases into the kiln to provide a purge gas with an oxygen content below about 2% for being conducted through the kiln adjacent the advancing material to displace the vapor from adjacent the surface of the advancing material; controlling the flow velocity of the purge gas to provide a relatively low velocity of from about 0.5 feet per second to about 10 feet per second to gently sweep the vapor from the material advancing through the kiln so as to avoid entrainment of particulate matter in the purge gas and to thereby produce an off-gas mixture containing the purge gas together with collected vapor and having a relatively low level of particulates; maintaining air infiltration to the rotating kiln at a sufficiently low rate to avoid an increase in the level of oxygen contained in the purge gas flowing through the kiln to a level at which sufficient oxygen would exist to support combustion of organic vapors released from the materials; removing the off-gas mixture from the kiln; treating the off-gas mixture following the removal from the kiln to render the off-gas mixture acceptable for discharge to the atmosphere; and discharging the material from the discharge end of the kiln substantially free of the hazardous organic substances.