Cleaning and liquid contact with solids – Processes – Including work heating or contact with combustion products
Patent
1996-06-17
1999-07-20
Houtteman, Scott W.
Cleaning and liquid contact with solids
Processes
Including work heating or contact with combustion products
134 21, 134 39, 134 40, B08B 700
Patent
active
059251948
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an apparatus and a method for use in de-oiling components.
In industry, assemblies of pressings, such as evaporators, radiators, air-conditioning units and the like are formed of layers of aluminium alloy strips which have been brazed together. During pressing, the strips are often contaminated with the oil used to lubricate the presses and such oil must be removed prior to the brazing operation taking place. In the past, this de-oiling was carried out using solvents however, due to environmental concerns, use of such solvents is now discouraged.
One recently introduced method of de-oiling such components involves heating the contaminated components to temperatures between 250.degree. C. and 350.degree. C. in a vacuum furnace. The vacuum is achieved through use of Roots blowers and rotary piston pumps. However, this arrangement has encountered numerous problems including the relatively low viscosity oil being removed from the components condensing in the piston pump and either causing the pump to seize, due to the thinning of the pump lubricating oil, or the loss of vacuum due to the relatively high vapour pressure of the press lubricating oil. In order to minimise these problems, cryogenic condensers have been provided between the furnace and the piston pump with the intention that the oil vapour will be trapped in the condenser, and thus will not contaminate the pump. In practice, such condensers are only 80% efficient and a considerable quantity of oil still reaches the piston pump.
Further, there are a number of risks associated with the use of such vacuum furnaces. In particular, if any oil droplets remain in the furnace there is a risk that these will ignite, and cause an explosion, when the hot furnace is opened to remove the de-oiled components.
It is among the objects of the embodiments of the present invention to obviate and mitigate these disadvantages.
According to the present invention there is provided apparatus for use in de-oiling components, the apparatus comprising: ring pump, wherein oil is utilised to form the liquid ring and the oil is selected to be compatible with or the same as the oil to be removed from the components.
According to a further aspect of the present invention there is provided a method of de-oiling contaminated components, the method comprising the steps: form the liquid ring; and the oil to be removed from the components.
As used herein, the term "oil" is intended to encompass oils, greases and the like as may be used for lubrication and cooling of machinery, tools and components.
In use, the invention allows the vaporised oil from the components heated in the furnace to condense within the pump, or in the pipework leading to the pump, without adversely affecting the operation of the pump. Any excess oil collecting in the pump is simply drained away for disposal or separation and re-use. Thus, the need to periodically replace "contaminated" pump oil is obviated. Also, apparatus necessary for condensing the vaporised oil before it reaches the pump, such as the cryogenic condensers provided in conventional systems having rotary piston pumps, may be omitted, providing a significant saving in plant costs: a simple heat exchanger.backslash.condenser may be provided on the pump exhaust to condense any oil vapour which passes through the pump.
Preferably, the system includes lobed pumps, most preferably one or more Roots blowers. As the operation of these pumps is unaffected by the presence of oil vapour in the air being drawn from the furnace such pumps may be provided between the liquid ring pump and the furnace. Most preferably, these pumps are vertically spaced to minimise collection of condensate therebetween.
Preferably also, the furnace is provided with heating means spaced from the walls of the furnace chamber, to facilitate cooling of the heating means and the components at the end of a de-oiling cycle, before opening the chamber: if the furnace temperature is high on opening the chamber there is a risk of explosion through ignition of any
REFERENCES:
patent: 4141373 (1979-02-01), Kartanson et al.
patent: 4329201 (1982-05-01), Bolton
patent: 5614029 (1997-03-01), Nakatsukasa et al.
Vacuum Deoiling for Environmentally Safe Parts Cleaning, by W. Mitten, pp. 29-31, Metal Finishing; vol. 89, No. 9; Sep. 1991.
Corstorphine John
Wilson John Glencross
Consarc Engineering Limited
Houtteman Scott W.
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