Textiles: fluid treating apparatus – Machines – Combined
Reexamination Certificate
2000-05-24
2001-06-19
Coe, Philip R. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Combined
C068S0180FA, C068S207000, C134S107000
Reexamination Certificate
active
06247340
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fluid based cleaning method and system, particularly for the cleaning of garments, fabrics, substrates, complex materials or the like, but also for sterilizing purposes. More specifically, the invention relates to the supplying of a cleaning fluid, particularly liquid carbon dioxide, pure or with additives, to a customer application system of said cleaning system.
Conventional dry-cleaning devices use solvents, which are risky as regards health and safety, and environmentally detrimental. For example, perchlorethylene is possibly carcinogen, while petroleum based solvents are flammable and produce smog.
Liquid carbon dioxide has been proposed as a dry-cleaning fluid, see, e.g., U.S. Pat. No. 5,784,905 and No. 5,683,473 issued to Townsend al. and to Jureller et al., respectively, and references therein.
Liquid carbon dioxide has many attractive properties for use as a dry-cleaning medium; it is an inexpensive and unlimited natural resource, that is non-toxic, nonflammable, and does not produce smog, or deplete the ozone layer. It does not damage fabrics or dissolve common dyes, and exhibits solvating properties typical of hydrocarbon solvents.
A typical liquid carbon dioxide based dry cleaning system includes a confined high-pressure chamber for containing liquid carbons dioxide in liquid phase, at typical process temperatures of about 0° to 30° C., and at typical pressures of 35 to 70 bar. A high-pressure tank or reservoir is provided for supplying liquid carbon dioxide to the confined chamber. The carbon dioxide solvent may contain various additives, such as surfactants, antistatic agents, fragrance and deodorizing agents. The confined chamber may include a basket or a drum to hold the objects to be cleaned. There may be provided an agitation means or some other means for agitate or move the liquid carbon dioxide relative to the objects. Example of such a liquid carbon dioxide dry cleaning system is discussed in said U.S. Patents and in U.S. Pat. No. 5,467,492 issued to Chao et al.
When using such a cleaning system the solvent is “consumed”, i.e., and, even though the solvent to some extent may be decontaminated through filtering, it will finally become useless and has then to be purified, e.g., through distillation.
A problem with this kind of dry-cleaning system is that nonavoidable losses of carbon dioxide to the atmosphere arises as a consequence of opening the cleaning chamber for loading and unloading of objects. Also, other types of losses occur during operation, e.g., due to venting of non-condensed carbon dioxide to the atmosphere. These losses are troublesome, as the dry-cleaning device needs a certain amount of carbon dioxide to operate properly.
Prior art liquid carbon dioxide dry-cleaning systems solves this by dimension the high-pressure tank or reservoir so that there is enough carbon dioxide for a predetermined number of cycles. Then carbon dioxide has to be supplied to the drycleaner. This is generally performed at regular time intervals, e.g., every second week, by delivery of carbon dioxide from a mobile tank, e.g., a tank lorry.,
A problem, here, is that the tank/reservoir gets very large, and as a result the dry-cleaner becomes bulky and as a consequence, difficult to place.
Very compact dry cleaners, where restrictions are put on the size of the tank/reservoir, would need delivery of carbon dioxide very frequently; or would otherwise suffer from malfunction due to lack of carbon dioxide.
Another problem is that the pressure in the tank/reservoir is higher than the most common pressure in tanks for distribution of carbon dioxide or carbon dioxide based products. A higher pressure, sufficient for filling the tank/reservoir, could be achieved by, for example, using a high-pressure delivery tank, which, however, will be heavy and reduce the capacity of the truck for other goods.
An alternative is to use a pump installed either at the delivery tank, which will be costly, noisy and hard to operate, particularly when a small distrbution tank is used, or at the customer place (dry-cleaner system) and connected to a low pressure tank to which the liquid from the delivery tank is filled, which will be costly because a pump is needed, and also higher maintenance costs are expected.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an easy, fast, and convenient method for supply of a cleaning fluid, particularly carbon dioxide, or a carbon dioxide based fluid, from a low-pressure customer supply system to a high-pressure customer application system (dry-cleaning device).
It is a further object of the invention to provide a fluid based cleaning system, which eliminates the problems associated with the prior art as discussed above.
These objects, among others, are fulfilled, according to one aspect of the present invention, by a method for supplying low-pressure liquid cleaning fluid to a high-pressure cleaning/sterilizing system comprising a high-pressure storing/working vessel, a cleaning chamber, and a compressor. The method comprises supplying liquid cleaning fluid to the cleaning chamber from a low-pressure supply vessel by means of differential pressure, and transferring gaseous cleaning fluid from the cleaning chamber to the high-pressure storing/working vessel by means of the compressor.
Preferably, the step of transferring comprises condensing the gaseous cleaning fluid before entering it into the high-pressure storing/working vessel.
According to a second aspect of the present invention, there is provided a method for cleaning or sterilizing objects in a liquid fluid cleaning system comprising a high-pressure storing/working vessel, a cleaning chamber, and a low-pressure supply vessel. The method comprises loading the cleaning chamber with objects to be cleaned or sterilized, supplying cleaning fluid to the cleaning chamber from the low-pressure supply vessel by means of pressure difference, supplying cleaning fluid to the cleaning chamber from the high-pressure storing/working vessel, cleaning the objects in the cleaning chamber with the cleaning fluid, transferring cleaning fluid from the cleaning chamber to the high-pressure storing/working vessel, and unloading the cleaned objects from the cleaning chamber.
According to a third aspect of the present invention, there is provided, in a liquid fluid based cleaning system, comprising a high-pressure customer application system including a cleaning chamber and a storing/working tank interconnected via a first tube system, a method for the cleaning or sterilizing of objects, e.g., garments, fabrics, substrates, complex materials or the like. The method comprises loading the objects to be cleaned or sterilized into the cleaning chamber; closing the cleaning chamber; evacuating major part of the air in the cleaning chamber; supplying a predetermined amount of cleaning fluid, pure or with additives, to the cleaning chamber from a customer supply system including a low-pressure liquid supply tank with cleaning fluid, pure or with additives, of a pressure higher than the present cleaning chamber pressure via a second tube system by simply, during a predetermined period of time, opening a valve of said second tube system; cleaning or sterilizing the objects by, during a predetermined period of time, circulating cleaning fluid, pure or with additives, or by agitating the objects; emptying the cleaning chamber from major part of the cleaning fluid by transfer it to the storing/working tank; opening the cleaning chamber, and thereby letting a predetermined amount of cleaning fluid leave the application system, which amount corresponds mainly to the supplied amount of cleaning fluid or to the supplied amount of cleaning fluid divided by some integer; and unloading the cleaned or sterilized objects.
Preferably carbon dioxide is chosen as the cleaning fluid.
According to a fourth aspect of the present invention there is provided a fluid based cleaning system, which implements the above aspects of the present invention.
An advantage
Lindqvist Kenneth
Svensson Orvar
AGA AB
Coe Philip R.
Pearne & Gordon LLP
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