Patent 6135765
Pyrocleaning Furnace & Thermal Oxidizer System
This patent is a combination of a Burnerless Pryocleaning Furnace and a Thermal Oxidizer systems, which degreases mostly aluminum and some steel components, covered with organic lubricating and/or cutting oils.
A Pyrocleaning Furnace and Thermal Oxidizer System which degreases metal components and comprised of an oven, oxidizer, a gas supply and exhaust, and primary heat exchanger. Degreasing is accomplished by first transporting the metal components through the oven and exposing the oil coated metal components to hot gases which have a temperature above the vaporization point of the oil, but not one that is exceedingly high thereby also preventing the thickening of the oxide layer of the metal components. Upon contact with the metal components, the gases cause the oil to evaporate from the metal components. The resultant hydrocarbon-filled surrounding gases are then quickly evacuated from the oven and transported to the oxidizer. The oven also includes one low and one high pressure gas supply, which together serve as the heating source for the oven. The high pressure gas supply also acts to increase the evaporation rate of the oil, and thereby decrease the resident heating time of the metal components, by impinging and creating a fluttering action on the metal components. A second heat exchanger, in addition to the first heat exchanger, provides efficiency to the system.
There is a critical line of operating temperature between vaporizing the oil and avoiding oxidization of the metal components. This patent addresses the fine line of operating temperatures.
In this particular case, high pressure and low pressure hot air as a medium of heat exchange were used to accomplish vaporization without oxidization.
VOC-laden exhaust goes to the Thermal Oxidizer, comprising of Primary and Secondary Heat Exchanger. Primary Heat Exchanger preheats the VOC-laden air before entering the Incineration Chamber.
VOC-laden exhaust gases are oxidized using the combustion process. Elevating the temperature causes exothermic reaction, and the heat is released from the processed air, which raises the temperature in the Incineration Chamber. The hot gases are held for 1+ second residence time and then continue their path and preheat the incoming gases in the Primary (Preheat) Heat Exchanger. And, then continue on to the Secondary Heat Exchanger.
Secondary Heat Exchanger provides hot air to the Burnerless Pyrocleaning Furnace (Oven). This whole system is very compact, with the Incineration Chamber, Primary and Secondary Heat Exchanger as part of one compact assembly.
This patent was developed for an automobile manufacturers, when Trichloroethylene (TCE) was banned as a Degreaser. This thermal cleaning system is a novel approach to cleaning of aluminum parts.
