Incineration fume system

Design considerations and costs of the catalyst, hardware, and a fume control system are direcdy proportional to the oven exhaust volume. The size of the catalyst bed often ranges from 1.0 m at 0°C and 101 kPa per 1000 m /min of exhaust, to 2 m for 1000 m /min of exhaust. Catalyst performance at a number of can plant installations has been enhanced by proper maintenance. Annual analytical measurements show reduction of solvent hydrocarbons to be in excess of 90% for 3—6 years, the equivalent of 12,000 to 30,000 operating hours. When propane was the only available fuel, the catalyst cost was recovered by fuel savings (vs thermal incineration prior to the catalyst retrofit) in two to three months. In numerous cases the fuel savings paid for the catalyst in 6 to 12 months. 

The system is mounted on two mobile trailers. The first trailer contains a rotary kiln in which soil is heated to 300 to 600°F. The off-gas is ducted from the rotary kiln to a cyclone separator where relatively coarse matter is removed and a heat exchanger cools the gas to about 400°F. The cooled off-gas goes to the baghouse, which filters relatively fine particles from the off-gas stream. The final unit is an afterburner or fume incinerator that heats the contaminated air to approximately 1800°F to destroy the contaminants. 

Environmental concern with reference to PVC and the fact that burning (possibly as a distinction from controlled incineration) may generate obnoxious acid fumes has created pressure on the pharmaceutical industry to move away from PVC. The alternative materials which have been considered include PET (polyester) and PP (polypropylene). Both require higher softening temperatures than PVC and good heat control, which can be more readily achieved with modem equipment with an effective preheat system. However, this only applies to certain selected and special material grades. Although these materials can be coated with PVdC to improve the moisture barrier, there are pressures to ban PVdC as it also contains a chloride component. Suffice it to say that the replacement of PVdC and its associated barrier/heat seal features may not be easy to achieve. Current opinion is that PVC will not be replaced. 

Other configurations of treatment processes using thermal desorption as the primary separation technique can be applied to organically contaminated soils. Alternative physical/chemical processes can be used to treat the desorber off-gas and the contaminants. To achieve complete contaminant destruction, the off-gas can be treated by using conventional fume incineration or other thermal treatment technology. The choice of the type of desorber and off-gas treatment system depends on the concentration and properties of the chemical contaminants, soil characteristics, quantity of contaminated material, site characteristics, availability of off-site disposal, and regulatory and related requirements. 

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