Drying and gas or vapor contact with solids – Process – Gas or vapor pressure is subatmospheric
Reexamination Certificate
2002-07-29
2004-05-25
Rinehart, K. B. (Department: 3749)
Drying and gas or vapor contact with solids
Process
Gas or vapor pressure is subatmospheric
C034S092000, C034S402000, C034S407000, C034S408000, C034S468000, C134S021000
Reexamination Certificate
active
06739073
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to method and apparatus for performing wet clean, dry clean, vacuum heat drying, and vacuum freeze drying in one process without using a vacuum system, and capable of recovering low-pressure gas used in dry clean, and recovering cleaning solution and waste solution to achieve environment protection and energy saving. The apparatus includes at least one drain-to-vacuum apparatus, at least one vacuum vessel produced from the drain-to-vacuum apparatus, at least one heat control unit for vaporizing or sublimating cleaning solution, at least one heat egress unit for condensing vapors of the cleaning solution, and other auxiliary instruments, including a plurality of connection pipes. A low-dissolved-air cleaning solution is used and a drain-to-vacuum process is performed on the drain-to-vacuum apparatus, such that a cleaning vessel, which is not fully filled with the cleansing solution, becomes a vacuum vessel having very low internal air pressure and vapor pressure from the cleaning solution, enabling a minimized influence of any air pressure on any operation performed on the cleaning and vacuum drying apparatus. The present invention employs physical features that boiling points of general liquids lower with reduced pressure, that liquid saturated vapor pressure reduces with lowered temperature, and that two vacuum vessels of different working temperatures would have a pressure differential between their saturated vapor pressures, so that the enclosed cleaning vessel in a sealed state can be directly used to perform vacuum heat drying or vacuum freeze drying after dry and wet cleans have been completed therein. Therefore, wet clean, dry clean, vacuum heat drying, and vacuum freeze drying can be completed in one process, and low-pressure gas used in dry clean and cleaning solution and waste solution can be recovered to achieve environment protection and energy saving.
BACKGROUND OF THE INVENTION
In a general cleaning and drying process, there is usually provided one or multiple clean working vessels, at where a workpiece is cleaned before being transferred to a next work platform for drying. For a finished product subject to heat deterioration, vacuum drying is particularly needed. When a cleaned finished product is moved in and exposed to atmosphere, it would be contaminated by particles again. Thus, it is desirable to develop a method to complete cleaning and vacuum drying of a workpiece in the same one cleaning vessel without the need of using an expensive vacuum system and to largely reduce related manufacturing costs.
It is a common practice in a cleaning process to use chemical solutions to clean off residual substances on the workpiece surface, such as particles, oxides, metal impurities, oil films, etc. It is possible that hazardous substances leak due to vaporization during the cleaning process. Such hazardous substances tend to explode and cause fires, resulting in serious damages and losses and adversely affecting operators' health. Therefore, a cleaning system using enclosed vessels has advantages of reduced consumption of chemical solutions and pure water, and reduced emission of waste gases and reduced draining of waste water, as compared with a conventional open cleaning system.
In a known cleaning process using enclosed vessels, an amount of cleaning solution is introduced into an enclosed cleaning vessel that is sealed in a predetermined manner, and auxiliary equipment of the cleaning vessel removes contaminants from the surface of the workpiece. After the cleaning is completed, the cleaning solution is drained and the cleaned workpiece is removed from the cleaning vessel and transferred to another work platform for drying.
In a known dry clean process, a vacuum system is employed to draw air out of the cleaning vessel to produce vacuum therein. Thereafter, a type of gas is introduced into the vessel to chemically react with the workpiece to be cleaned, so that oxides on the surface of the workpiece are reduced. The cleaning gas is then drawn, and the workpiece is washed with pure water to create very clean, particle-free surface having a layer of natural oxide film. However, the use of vacuum system considerably increases the cleaning cost.
In a known vacuum heat drying process, a vacuum pump is employed to draw a working vessel to produce proper degree of vacuum therein. The vacuumized working vessel is then heated at a low temperature, so that moisture and volatile matters in the workpiece to be dried vaporize into vapors that are drawn out with the vacuum pump to dry the workpiece. To protect equipment included in the vacuum system from too much heat and vapors produced during heating and vaporization, it is necessary to install refrigerant compressor system and other equipment on the working vessel leading the vacuum pump, so as to condense the gaseous vapors into liquid water. This prevents the existing vacuum heat drying process from being a good design.
In a known vacuum freeze drying process, a workpiece to be dried is first frozen until moisture in the workpiece is frozen into solid state. Thereafter, a vacuum drying vessel is drawn to produce vacuum and reduce internal pressure thereof, so that the solid-state water in the workpiece to be dried is sublimated and drawn to produce vacuum in the drying vessel. This process is disadvantageous because it uses a refrigerant compressor to freeze the workpiece to be dried and uses a vacuum pump to draw the vacuum drying vessel to produce vacuum therein at the same time. At this stage, liquid water in the workpiece to be dried has not yet been frozen into the solid state, and gas drawn out of the vacuum system contains saturated vapors from the vaporized liquid water. The saturated vapors tend to condense into drops in the vacuum system to damage parts and components thereof. Although it is possible to install a freezing system before the vacuum pump to freeze the saturated vapors contained in the air drawn out of the vacuum drying vessel, the drying cost would increase accordingly. Therefore, the existing vacuum freeze drying process is not a perfect design.
With the existing processes, cleaning operation and vacuum drying operation are separately conducted in different working environments. Therefore, a workpiece or a product could not be cleaned and vacuum dried in the same one cleaning vessel, resulting in largely increased operating cost and considerable inconvenience in handling the cleaning and vacuum drying operations.
It is therefore tried by the inventor to develop improved method and apparatus for performing multiple cleaning and vacuum drying operations to eliminated is advantages existing in the above-mentioned conventional cleaning and vacuum drying techniques.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide cleaning and vacuum drying method and apparatus for performing multiple operations of wet clean, dry clean, vacuum heat drying, and vacuum freeze drying in enclosed vessels in one process without using a vacuum system, and capable of recovering low-pressure gas used in the dry clean and recovering cleaning solution and waste solution to achieve environment protection and energy saving.
The cleaning and vacuum drying apparatus of the present invention includes at least one drain-to-vacuum apparatus, at least one vacuum vessel created via the drain-to-vacuum apparatus, at least one heat control unit for vaporizing or sublimating the cleaning solution, at least one heat egress unit for condensing vapors, and other auxiliary apparatus, such as connecting pipes. The heat control unit vaporizes or sublimates the liquid or solid-state cleaning solution in the vacuumized cleaning vessel, and the heat egress unit condenses the gaseous cleaning solution in the vacuumized cleaning vessel into liquid or solid-state cleaning solution. The drain-to-vacuum apparatus uses low-dissolved-air cleaning solution and a drain-to-vacuum process to produce vacuum in the cleaning vessel, so that the cleaning vessel becomes a vacu
Rinehart K. B.
Rosenberg , Klein & Lee
LandOfFree
Method and apparatus for performing multiple cleaning and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for performing multiple cleaning and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for performing multiple cleaning and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3242331