Cleaning and liquid contact with solids – Processes – Including regeneration – purification – recovery or separation...
Patent
1990-06-26
1992-12-08
Morris, Theodore
Cleaning and liquid contact with solids
Processes
Including regeneration, purification, recovery or separation...
134 26, 134 34, 134 951, 134 981, 134111, B08B 300, B08B 312
Patent
active
051694549
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to a method for cleaning objects with environmentally harmful solvents, particularly halogenated hydrocarbons, in a system which is substantially closed during the cleaning process.
Solvents can lead to considerable damage to the environment due to inexpert storage, handling and transport or inexpertly returning them after they are contaminated to preparation plants or to storage, e.g. if they are spilled and enter the soil or groundwater. On the other hand, particularly dangerous materials, such as halogenated hydrocarbons (HKW), possess outstanding solvent properties for industry; they are also desirable because they are inflammable. However, legislation allows their use only in a very restricted scope, e.g. in such a way that only 10 l may be available per work place.
In particular, cold cleaning systems based on organic solvents are known in which the drying of the solvent is effected by air. Some systems are known which guide air via activated charcoal filters; however, emission into the environment is not reliably prevented. The weak points of known methods or apparatuses therefore lie in the handling, storage and transporting of such solvents.
SUMMARY OF THE INVENTION
Therefore, it is the object of the present invention to provide a solution which simplifies the transporting and, in particular, the handling of such solvents, wherein injury to persons and, environment is simultaneously reduced to a minimum or completely prevented, and which achieves an optimal utilization and recovery of the solvent in particular.
This object is met, according to the invention, with a method of the type named in the beginning in that a portion of this solvent is conveyed into a processing space from a large-volume reservoir tank of solvent, in that the objects to be cleaned are subsequently wetted with the solvent located in the processing space and cleaned by means of it, the solvent is returned to a collecting tank from the processing space after one or more cleaning processes and/or the gas atmosphere in the processing space is filtered and cleaned before the removal of the cleaned objects.
Cold cleaning methods in particular can be carried out practically in a closed system by means of the invention. A loading of the environment, particularly the surrounding air, is accordingly prevented. A very special advantage of the invention consists in the optimal utilization of a solvent by means of removing the solvent partially or by portions from the reservoir tank for fresh solvent and keeping this solvent available in the area of the processing space until it is so highly contaminated that it is returned for regeneration. When this degree of contamination is reached it can be guided back into the second tank. Accordingly, a comparatively pure or entirely pure solvent is always available for the user of the system.
It is provided with respect to construction that at least two reservoir chambers assigned to the processing space are used for substantially contaminated solvent on the one hand and for pure solvent on the other hand, wherein a pre-wash stage with the contaminated solvent is carried out prior to the main wash stage. This construction makes it possible to implement the method in a particularly economical manner and manages quantities of solvents carefully, wherein the frequency of regeneration of contaminated solvent is additionally reduced. Instead of two reservoir chambers, a plurality of corresponding reservoir chambers can also be provided which can receive a volume of solvent necessary for processing. In so doing, the degree of contamination in the chambers can increase by stages depending on the number of pre-wash stages; the most highly contaminated solvent is used for pre-washing in a pre-wash stage, a second pre-wash stage is carried out with the subsequent somewhat cleaner solvent until the final cleaning is finally effected with the cleanest solvent. If the degree of contamination in the most highly contaminated stage is so high that a pre-w
REFERENCES:
patent: 3079286 (1963-02-01), Kearney et al.
patent: 4409999 (1983-10-01), Pedziwiatr
patent: 4560417 (1985-12-01), Bardina et al.
patent: 4844743 (1989-07-01), Koblenzer et al.
Chaudhry Saeed
Morris Theodore
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