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1. Field of the Invention
The invention relates to a method of dry cleaning textiles which are washed with solvent and dried by hot air, the solvent being recovered after condensation.
2. Brief Description of the Background of the Invention Including Prior Art
With the ban on HCFCs and the sharp decline in the public acceptance of per(tetra)chloroethylene, dry cleaning systems intended for hydrocarbon solvents, i.e. very largely aroma-free solvents which are members of the alkane group, are becoming increasingly important. The flash point of these solvents is above 55° C. Some of these solvents are non-toxic solvents and are therefore subject to providing breeding grounds for bacteria and fungi colonies.
Dry cleaning machines operate as a closed system and are responsible not only for cleaning goods but also for drying them, at the same time as they recover the solvent employed by condensing and regenerating it (distillation, adsorption). It is strongly desired that such dry cleaning machines do not contaminate the clothes cleaned with bacteria or fungi.
The use of flammable hydrocarbon solvents with their low vapor pressures and high boiling ranges has created new requirements which the drying process needs to meet with regard to optimum fire safety conditions, to drying times, to the use of energy and to the environment. It is strongly desired that such solvents remain free from contamination.
Drying in dry cleaning systems is affected by a large number of varying conditions: these are the nature and quantity of the goods to be cleaned and the amount of residual solvent left in them after spin drying, the physical properties of the solvent used, the thermal energy applied and the volume flow of the recirculated air. These conditions vary from one load to the next. When there are large amounts of clothes to be cleaned there is always the danger that a detrimental organism is carried from one piece of clothes to another piece of clothes during the dry cleaning operation.
Hitherto the drying process in dry cleaning systems has been controlled by time and the temperature of the recirculated air using empirical values, which the machine operator presets at his own discretion. The consequences of controlling the process in this way are either: overdrying of the goods due to excessively long drying times, resulting in possible damage to the goods, excessive energy consumption and a reduction in the machine's handling capacity, or insufficient drying due to excessively short drying times, with the result that the goods are not dried sufficiently well and the residual solvent gives rise to additional emissions and may, under certain circumstances if in contact with the skin for fairly long periods, cause skin irritation. Any additional irritation of the skin by bacteria or fungi transferred during dry cleaning is undesirable.
This problem is of particular concern from the environmental and health points of view because what tends to be found in practice, due to inadequate measuring and sanitary techniques and economic considerations, is underdrying rather than overdrying. An antibacterial system is desirable which does not interfere with the drying process of a dry cleaning machine.
Also, with flammable solvents, there may be conditions in which the concentration in the recirculated air in the drying system rises above the lower explosive limit. To avoid fires or explosions, primary safety measures are taken. The removal of bacteria and fungi from clothes to be dry cleaned should not interfere with the safety of the dry cleaning operation.
1. Purposes of the Invention
The object of the invention on the other hand is to avoid on the one hand the cost and complications occurring in the past based on bacteria or fungi infestations in dry cleaning apparatus. The recirculated solvent in the dryer is furnished with ozone from an ozone generator for providing bacticidal and fungicidal effects. The present invention renders the dry cleaning procedures employed into more sanitary processes.
These and other objects and advantages of the present invention will become evident from the description which follows.
2. Brief Description of the Invention
The present invention provides a method of adding ozone to a solvent in a dry cleaning machine into the solvent line at the point where the solvent is leaving the solvent pump.
The addition of ozone to the cleaning solvent prevents the establishment of bacteria or fungi colonies in a dry cleaning machine.
The novel features which are considered as characteristic for the invention are set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
In the accompanying drawing, in which are shown several of the various possible embodiments of the present invention:
FIG. 1 is a view of a schematic diagram illustrating the operation and construction of a dry cleaning machine with ozone generator,
FIG. 2 is a view of a schematic diagram illustrating a second embodiment of the invention,
FIG. 3 is a view of a flow diagram showing the process steps.
Ozone is generated by ultraviolet radiation. Ozone (O3) is generated by irradiating air or oxygen (O2) with ultraviolet radiation. Ozone is a molecule of oxygen that is formed when three atoms of oxygen are bound together instead of the normal two atoms. The additional oxygen atom renders ozone a most powerful oxidizer and/or sanitizer readily available.
Ozone is employed as a bacteria killer in accordance with the present invention.
Ozone operates essentially as an oxidizer. When ozone is used in oxidizes a large portion of any contaminants, bacteria, fungi. Ozone furthermore disinfects. When ozone decomposes it does not leave any residue with the exception of regular oxygen molecules (O2).
Since ozone is unstable and quickly decomposes to regular oxygen under the ambient conditions, ozone cannot be shipped or stored. Ozone is therefore produced at the location of use and for immediate use. The lifetime of ozone in standard air is about an hour. In the solvent of a dry cleaning machine the lifetime of ozone is shorter, but sufficient to purify and sanitize the solvent.
An ozone generator is connected to the solvent line. The ozone generator can preferably be switched on together with the solvent pump such that the ozone generator is running when the solvent pump is running. The ozonization will occur when the solvent pump is running.
The ozone generation is based on electrical power. The ozone generator comprises an ultraviolet lamp powered by electrical current. The light of the ultraviolet lamp is directed to a chamber containing air or being flown through by air. The interaction of the ultraviolet radiation with the air in the chamber converts part of the oxygen in the air into ozone molecules. If a sufficient number of regular oxygen molecules has been converted into ozone, then the air in the chamber containing the ozone is lead out of the chamber and fed to the solvent of the dry cleaning apparatus.
The ozone generator produces ozone when air is drawn across a high energy vacuum ultraviolet lamp for converting some air to ozone.
The electrical power employed for the ultraviolet lamp of the ozone generator can be standard electrical grid voltage of for example 120 volts or 240 volts.
Generally the ozone generator 105 will contain a gas pump for moving the ozone containing air from the irradiation chamber to the solvent pipe. The gas pump is preferably powered by electricity.
The hose for leading the ozone containing air from the chamber to the solvent can be from about 1 mm to 2 cm diameter and preferably is of a diameter of from about 0.5 to 1 cm. A quarter inch hose will usually serve well for leading the ozone containing air from the ozone generating chamber to the pipe containing and transporting the solvent. Preferably a ¼ in check valve 101 is placed in the ozone conducting pipe 107 for avoiding the possibility of solvent flowing back to the ozone generator.
The ozone is introduced into the solvent by an injector 103 either by direct diffusion (sparging) or with a bypass Venturi system. When direct diffusion is employed the ozone containing air is forced through a porous metal disk, which creates extremely fine bubbles of ozone containing air. As the bubbles move into the solvent, the ozone is to disperse into the solvent where the ozone is able to react with bacteria and fungi. If the ozone is introduced through an air Venturi pipe suitable for passing ozone, then bubbles of ozone are generated at the outlet end of the air Venturi pipe.
The ozone generator should be mounted on a solid surface with a wood or sheet metal screws.
Suitable ozone generators are those which are commercially available for example in connection with ozone water purification systems. The ozone generator can be of the type sold by Prozone International, Inc.
The solvent can be a hydrocarbon solvent, a silicon solvent, Rynex, Perc, alcohol, pentyl-acetate, siloxane solvent.
The use of nontoxic solvents can be associated and lead to bacteria growth. The solvents employed for dry cleaning in the cleaning process can be chlorinated solvents, organic solvents, alcohols, esters, ketones, hydrocarbon solvents, perfluorocarbons, hydrofluorocarbons, volatile solvents, methyl siloxanes, monoclorotoluene, benzotrifluorides. Preferred solvents include chlorinated solvents, alcohols, esters, ketones, hydrocarbon solvents, siloxanes, monoclorotoluene, benzotrifluorides.
The solvent is pumped by the pump 109. The temperature of the solvent is adjusted in a heat exchanger 111 and then fed in four branches to valves V7, V8, V9 and V12.
The valve V7 leads to the filter 1. The valve V7 allows the solvent to get to the drum across through filter 1.
The valve V8 leads to the filter 2. The valve V8 allows the solvent to get to the drum across through filter 2. The filter 1 is connected to the filter 2.
The valve V9 and the valve V 10 allow the solvent to get to the drum bypassing the filter 1 and the filter 2.
The valve V11 connects a button trap or bottom trap to the solvent pump.
The valve V12 allows the solvent to get to the drum across a carbon filter.
The valve V13 controls the drive of the brush in the button trap.
The valve V1 controls the connection from the tank 2 to the solvent pump 109.
The valve V2 connects the tank 2 to the solvent pump.
The valve V3 connects the solvent pump to the tank 3 to allow for tank cleaning.
The valve V4 connects to the tank 2 and controls feeding the tank 2.
The valve V5 connects to the tank 1 and controls feeding the tank 2.
The valve V6 connects to the tank 3 and controls feeding the tank 2.
The valve VL allows for feeding the distillation process from tank 3.
The pump VP powers and feeds a distillation circuit.
A water separator WA is provided for separating water from the cleaning solvent.
The draining distillation DA is connected to the ventilation distillation DB.
The valve DD controls the steam supply to the distillation. The valve DT controls the steam supply to the steam heater and to the drying process. The valve DT is connected to the condenser K.
The waste air is exhausted by an air exhauster KA1.
Ventilation of the apparatus is furnished by the ventilator KA2 disposed near the condenser K. A valve KD is provided for the cooling water.
An impregnation dosing pump RV is furnished to adjust the amount of impregnant to be furnished during the cleaning process.
A soap dosing pump SP is furnished to adjust the amount of soap to be furnished during the cleaning process.
The heat exchanger FC10 is employed for heat exchange in connection with distilling the solvent. The heat exchanger FC12 is employed in connection with furnishing an appropriate temperature to the solvent.
The elements Y16-Y53 provide output lines from the PLC and are controlling the valves.
A safety lock TV is provided for locking the door of the dry cleaning machine.
Solvent is furnished to tank T1 shown in FIG. 2. The solvent is transported out of the tank T1 with a solvent pump P1. Ozone is generated in the ozone generator 105 and fed through ozone conducting pipe 107 and through check valve 101 to the line junction with the injector 103 to be mixed with the solvent stream coming from the solvent pump P1. The mixture of solvent and ozone is feed through the heat exchanger 11 serving as a solvent cooler. The mixture is then fed through valves V9 and V10 to the drum D. An upper discharge of the drum D for substantially gaseous components leads to a lint filter LF for catching lint. The filter part of the lint filter is removable and can be cleaned or replaced. The gaseous discharge of the drum is then fed through a condenser C. The resulting condensate is transported to a water separator W. The solvent separated in the water separator W is then returned to one of the tanks T1, T2 or T3 through a respective valve V4, V5 or V6.
The gaseous discharge of the condenser C is sucked up by a blower B and transported to a heater H. The heated gaseous medium mostly consisting of hot air is then returned from the heater H to the drum D.
A lower discharge port of the drum D is mostly concerned with solid and liquids collected in the drum. The lower discharge port is connected to a button trap BT for separating solid particles and buttons. The discharge of the button trap BT is returned through valve V11 to the solvent tanks T1, T2, T3 or to the solvent pump P1.
A part of the solvent in tank T3 is fed through the heat exchanger FC12 and the valve VL to the distilling container S. The distillate from the distilling container S is fed through a vacuum pump P2 and a heat exchanger FC10 to the solvent tank T2.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of dry cleaning system configurations and cleaning processing procedures differing from the types described above.
While the invention has been illustrated and described as embodied in the context of an antibacterial dry cleaning system, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.