Heating – Work chamber having heating means – Having means by which work is progressed or moved mechanically
Reexamination Certificate
2000-05-30
2001-06-05
Wilson, Gregory (Department: 3749)
Heating
Work chamber having heating means
Having means by which work is progressed or moved mechanically
C432S011000, C432S018000, C432S128000, C432S198000, C266S171000
Reexamination Certificate
active
06241515
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermal processing apparatus for treating a heat treatable material, more particularly to a device and method adapted for use in conjunction with a thermal processing furnace to treat combustibles generated therein by converting the same to harmless byproducts.
BACKGROUND OF THE INVENTION
Thermal processing concerns the heat treatment of a heat treatable material (e.g. metal parts). The heat treatable material is heated to a desirable temperature and then cooled at a controlled rate. Thermal processing includes heat treating operations such as sintering, brazing, annealing, carburizing, and the like which require heating of materials to yield a particular material having selected physical properties. Prior to thermal processing, the material is typically formed into a compressed form from a powder in a desired shape or simply pre-casted or pre-formed as a solid piece.
Furnaces are utilized to carry out thermal processing either continuously or batchwise. Continuously operated furnaces have a length, typically of 50 to 100 feet and include a conveyor belt assembly for moving the parts for processing through the furnace. Batch furnaces typically have a shorter length. Such furnaces typically include an entryway for introducing the heat treatable material and an exitway for retrieving the heat treatable material as a finished part. The size of the entrance and exit openings may be adjusted by movable doors to accommodate parts of various sizes and shapes and to maintain the furnace atmosphere therein. The heat treatable material moves through the entryway and is carried within the furnace by the conveyor belt. The to remainder of the furnace is substantially gas-tight and thereby closed to the outside atmosphere.
Within the furnace, the heat treatable material is usually thermally processed in the presence of an atmosphere flowing therethrough. The atmosphere excludes ambient air which may interfere with the thermal processing, and functions as a heat treating gas to initiate a heat treating operation such as metal oxide reduction, carburizing, decarburizing, and the like. In addition, the atmosphere assists in removing undesirable vaporized materials from the thermal processing operation. The undesirable vaporized materials are derived from, for example, lubricants, binders, chemical vehicles, oils and the like. Removal of these materials from the heat treatable material may be performed before the onset of the thermal processing operation.
To remove undesirable vaporized materials before thermal processing, the atmosphere is usually introduced within the furnace in counter-current flow to the movement of the heat treatable material. The undesirable vaporized material which may in part be oxidized by the presence of residual oxygen may therefore be purged before the onset of the thermal processing operation.
Due to competitive and economic pressures, furnace operators typically exceed the rated capacity of a furnace to meet production orders. As a result, the undesirable vaporized materials are not completely oxidized before leaving the furnace creating environmental concerns. In addition, the undesirable vaporized materials may rise to dangerous levels within the furnace and associated exhaust systems thus creating safety and fire hazards. Still further, the undesirable vaporized materials may also remain in the heat treatable material resulting in inferior quality products. The increased production rate may also diminish the capacity of the furnace to properly heat the parts to a desired temperature for enabling complete thermal processing.
It would be of significant advantage in the art of thermal processing to provide a device adapted for association with thermal processing furnaces for increasing production output capacity and improving the quality of exhaust emissions while maintaining a high yield of quality products in a cost effective and energy efficient manner.
SUMMARY OF THE INVENTION
The present invention is generally directed to a device associated with, either integrally or as a removable attachment, a thermal processing furnace for the heat treatment of heat treatable materials and to methods and thermal processing furnaces employing the same. The device provides a reaction zone for the oxidation of combustibles (i.e. undesirable vaporized materials) obtained from the thermal processing furnace as well as combustibles which may be generated in the present device as the heat treatable materials pass therethrough. Control of the amount of oxygen and the temperature within the present device enables at least substantially complete oxidation of the combustibles into harmless byproducts without significant oxidation of the heat treatable material. In addition, the present device serves the additional purpose of pre-heating the heat treatable material.
The present device is comprised of a housing having first and second openings and a chamber located therebetween with means for transporting the heat treatable material through the device into the thermal processing furnace. The second opening is in communication with an interior portion of a thermal processing furnace and receives the atmosphere (i.e. a gas stream containing combustibles) from the thermal processing furnace. A gas supply assembly is associated with the chamber for supplying an oxygen-containing gas to the chamber at a temperature and velocity sufficient to mix and react the atmosphere containing the combustibles and oxygen-containing gas to oxidize the combustibles into harmless byproducts. Control of the oxygen content and temperature within the reaction zone of the chamber enables at least substantially complete oxidation of the combustibles while preventing any appreciable oxidation of the heat treatable material.
In one aspect of the present invention there is provided a device operatively associated with a thermal processing furnace, the device comprising:
a housing having first and second openings and a chamber located therebetween;
means for transporting the heat treatable material from the first opening to the second opening;
said second opening being in communication with a thermal processing furnace for receiving a thermal process generated atmosphere containing combustibles from said thermal processing furnace during the heat treatment of the heat treatable material; and
an oxygen-containing gas supply assembly for supplying an amount of oxygen-containing gas to the chamber at a temperature and velocity sufficient to mix and react the atmosphere containing combustibles and oxygen-containing gas to oxidize at least substantially all of said combustibles into harmless byproducts without substantially oxidizing the heat treatable material.
In another aspect of the present invention, there is provided a method of oxidizing at least substantially all of the combustibles obtained from a thermal processing furnace comprising:
operatively associating with a thermal processing furnace, a housing having first and second openings with a chamber communicating therebetween;
drawing a thermal process generated atmosphere containing combustibles from said thermal processing furnace through said second opening into said chamber;
delivering an amount of oxygen-containing gas to the chamber at a temperature and velocity into said chamber sufficient to mix and react the atmosphere containing combustibles and oxygen-containing gas to oxidize at least substantially all of said combustibles into harmless byproducts without substantially oxidizing the heat treatable material; and
removing the harmless byproducts from said chamber.
A thermal processing furnace including the device described above is also encompassed within the present invention.
REFERENCES:
patent: 4266967 (1981-05-01), Yamada et al.
patent: 4674975 (1987-06-01), Corato et al.
patent: 5248255 (1993-09-01), Morioka et al.
patent: 6106281 (2000-08-01), Materna
TAT Technologies, INC
Watov & Kipnes P.C.
Wilson Gregory
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