GB2060713A

GB2060713A - Treating fabric articles with solvents

Info

Publication number: GB2060713A
Application number: GB8032843A
Authority: GB
Original assignee: AMATEN SA
Current assignee: AMATEN SA
Priority date: 1979-10-10
Filing date: 1980-10-10
Publication date: 1981-05-07
Also published as: FR2467009A1; IT1193558B; DE3038148A1; IT8025187A0

Abstract

Articles such as clothes are treated using a solvent medium having a high boiling point. The solvent present in the articles at the end of the treatment is recovered by using a fan (5) to circulate an air stream which traverses these articles in a basket (1). The air stream is charged with solvent by the articles and then passes through a cooling unit in order to condense the solvent. The air is circulated in a closed circuit and, upon leaving the basket (1) passes successively through an evaporator (3) and a condenser (4) of a refrigerator which comprises, in the high pressure part of the refrigerant circuit downstream of the compressor (7), an auxiliary condenser (12) supplied with water or air. The operation is carried out in two phases with a first phase in which the auxiliary condenser (12) is not supplied with air or water and a second phase in which the auxiliary condenser (12) is supplied with air or water in such a way that the drop in the temperature of the air entering the basket (1) during the said second phase is of the order of at least 10 DEG C to 30 DEG C. <IMAGE>

Description

SPECIFICATION A method and a machine for treatment using a solvent medium The invention relates to a method and a machine for treatment by solvents or in a solvent medium, for example for the cleaning, scouring, milling, finishing, flameproofing and water-proofing of articles such as garments or fabrics.

After the operation of stirring with the solvents, the articles have to be spun and then dried while recovering the residual solvent by evaporation. A conventional dry cleaning machine carries out this operation in two stages. In the first stage, the drum or basket is traversed by an airstream which is heated to about 800C and is propelled by a fan. This air entrains a large proportion of the solvents which are recovered by cooling the air in a condenser. At a temperature of 800C there is a risk of fixing stains; of felting or denaturing the articles and of unsticking linings which have been stuck in. The second operation, known as deodorising, then involves circulating fresh air which is transmitted into the atmosphere after having traversed the articles.The temperature of the garments is lowered by it but still remains in the vicinity of from 50 to 550C which is not desirable as regards the handling and appearance of the garments.

The method just described also has other disadvantages: a) It necessitates high energy consumption both for heating the air transmitted into the articles and then for cooling it.

b) It necessitates high water consumption in the condenser.

c) It causes impermissible pollution during deodorisation.

d) It necessitates an appreciable consumption of solvents which are expensive products.

Various methods of overcoming these disadvantages have been proposed. It has thus been proposed that the deodorising air be passed over adsorbants such as activated carbon in order to improve recovery and reduce pollution. However, this process consumes a large amount of energy in the carbon regenerating phase.

It has been proposed that perchlorethylene, which is the most widely used solvent, be replaced by a fluorinated solvent having a lower boiling point in order to reduce the energy consumption. However, such a solvent is more expensive and mediocre in effectiveness. Furthermore, the low boiling point causes a greater loss by accidental evaporation. Consequently, such solvents are rarely used except for special applications such as for the cleaning of skins and very fragile articles.

In order to improve the use of these solvents having a low boiling point, it has already been recommended that the refrigerant from a refrigerator whose condenser serves to heat the solvent to be used for the condenser. The assembly forms a closed thermodynamic system, the refrigerator operating as a heat pump transferring heat from the condenser to the heater (see French Patent No. 2,035,303 and U.S.A. Patent No. 3,070,463). There is no need for a deodorising operation as the operating temperature of the condenser is sufficiently low for almost complete recovery of the solvents in a closed circuit. A saving in energy and in solvents, and a reduction in pollution are thus obtained.

However, this technique cannot be applied to solvents having a high boiling point, such as perchlorethylene, trichlorethylene and trichlorethane. It has been proposed that a refrigerated condenser, or a water condenser connected in series or parallel with a refrigerant condenser, be used for these solvents. In French Patent No. 2,130,523, the refrigerated condenser is used for deodorisation, recovery taking place in known manner. This refrigerated condenser is mounted in parallel on the heater. In French Patent No. 2,293,513, the refrigerated condenser follows the water-condenser in order to lower the air temperature and to reduce the limit of the saturation concentration of the solvent.

The heater of the air circuit is short-circuited during this operation.

A saving in solvents and a reduction in pollution are thus obtained with solvents having a high boiling point, but the problem of saving energy is not solved owing to the increase in energy expenditure necessitated by the refrigerated condenser, and the water consumption remains high.

According to the invention there is provided a method for the treatment of articles using a solvent medium having a high boiling point, in which the solvent present in the articles at the end of the treatment is recovered by using a fan to circulate an air stream which traverses these articles in a basket, is charged with solvent and then passes through a cooling unit in order to condense the solvent, wherein the air circulates in a closed circuit and, upon leaving the basket, passes successively through an evaporator, and a condenser of a refrigerator which comprises, in the high pressure part of the refrigerant circuit downstream of the compressor, an auxiliary condenser supplied with water or air, the operation being carried out in two phases with a first phase in which the auxiliary condenser is not supplied with air or water and a second phase in which the auxiliary condenser is supplied with air or water in such a way that the drop in the temperature of the air entering the basket during the said second phase is of the order of at least 1 00C to 300C.

The invention further provides a machine for the treatment of articles using a solvent medium permitting the use of solvents having a high boiling point, comprising a rotatable basket for receiving the articles which are to be treated with the solvent, means including a fan for causing an airstream to traverse the basket and the articles contained, and a condenser for cooling this airstream as it leaves the basket, wherein the air is circulated in a closed circuit, the air passing through an evaporator of a refrigerator with means for recovering the solvent and then through a condenser of the said machine and thence being returned to the basket by a fan, an auxiliary condenser being mounted in the fluid circuit of the said refrigerator downstream of the compressor, the said auxiliary condenser being dimensioned so that it is capable of lowering the temperature of the air entering the basket by about 1 OOC to 300C at least when it is started up, and means being provided for selectively interrupting the operation of the said auxiliary condenser in a first phase or for starting up the said auxiliary condenser in a second phase.

In the first phase, particularly if the solvent is perchlorethylene, the air at the inlet of the basket is brought to a temperature of the order of from 55 to 600C, this temperature adjustment preferably being accelerated by an auxiliary thermostatically-controlled heater.

The evaporator is thus at a temperature of approximately 00C and the majority of the solvent is recovered.

In the second phase, the auxiliary condenser causes a drop in the temperature of the air as it enters the basket either by lowering the temperature of the condenser of the refrigerator or by acting as a refrigerator which is thus short-circuited. The evaporator drops to a temperature lower than minus 1 OOC, almost all the residue of solvent is recovered and the temperature of the garments leaving the basket is lowered.

All the desired objects are thus achieved: i) Use of high boiling solvents; ii) Saving in energy; iii) Saving in water; iv) Saving in solvent; v) Elimination of pollution.

The invention will be described more fully below with reference to the accompanying drawings, in which: Figure 1 shows a diagram of a first embodiment, and Figure 2 shows a diagram of a second embodiment.

Figure 1 shows a machine which comprises a drum or basket 1 into which a pulsed flow or air can be transmitted by a fan 5. For the sake of simplicity, the drawing only shows one circular line although it comprises, in a known manner, a closed chamber with a rotating basket of circular cross-section located inside it.

A dust filter 2 is provided in an air outlet duct 1 5. Downstream of the filter 2, the air is transmitted to an evaporator 3 of a refrigerator which acts as a condenser, and the solvent is collected at 16. Once this air has been freed from solvents, it is sent to the condenser 4 of the said refrigerator which heats it and is sent back to the basket 1 via the fan 5. The air thus circulates in a closed circuit.

The refrigerator comprises a compressor assembly 7 which transmits a refrigerant such as a Freon (Registered Trade Mark) via a pipe 21 into the condenser 4 where it is chilled and is then transmitted into the evaporator 3 after release of pressure in a pressure reducer 11, whereupon the fluid is returned to the compressor 7 via a pipe 20. A heat-exchanger 8 which can be replaced in a known manner by a capacitance, is situated between the compressor 7 and the condenser 4. The drawing also shows a dehydrator 9 and a viewing window 10 for the passage of fluid.

This assembly constitutes a heat pump to which there is connected an auxiliary condenser 12 placed upstream of the condenser 4 and in which the coolant is cold water circulated in the pipe 1 7 controlled by the valve 13.

An auxiliary heater 6, for example an additional resistor, is provided between the fan and the basket 1. The heater 6 is provided with thermostatic control means (not shown), for example a probe placed in the basket 1.

The machine operates in the following manner: First Phase The following parts are started up simultaneously: (a) The compressor assembly 7 without circulation of water in the auxiliary condenser 12; (b) The fan 5; (c) The auxiliary heater 6 regulated to a temperature of about 500C.

The air circulating in a closed circuit is heated by the condenser 4 and then by the auxiliary heater 6 so that the temperature in the basket rapidly rises to about 500C. This rise in temperature is effected in a few minutes (approximately 3 to 5 minutes) and the auxiliary heating can then be switched off. The rise in temperature then continues due to the effect of the main condenser.

The air is saturated with solvent as it passes over the articles, thus causing a drop in temperature.

Its temperature is from about 300C to about 450C as it leaves the basket. It then passes through the dust filter 2 and then through the evaporator 3 of the refrigerator which is at a temperature close to OOC.

This first phase lasts approximately 1 5 to 20 minutes, and at least 95% of the solvent is recovered.

To avoid super-pressures in the refrigerating circuit, it is possible to provide a valve 14 equipped with regulating means using either a thermostatic probe 18 in the airstream downstream of the condenser 4 or directly using the pressure measured by a pressure detector 1 9 at the outlet of the compressor. This valve transmits into the condenser 1 a flow of cold water capable of ensuring that the pressure of the refrigerator does not exceed the desired maximum.

Second Phase After this first phase, the temperature equilibrium is modified by causing pulsed air to circulate in the auxiliary condenser with the aid of the valve 1 3 and by eliminating the auxiliary heater 6.

The temperature of the air traversing the fan 5 and entering the basket 1 drops gradually to a temperature below 300 C. Owing to this fact, it is heated slightly by the garments located in the basket, this heating being of the order of a few degrees.

In the evaporator 3, the air temperature drops to about minus 1 500 and the residue of solvent remaining in the garments is condensed.

When the basket is opened at the end of the cycle, the temperature of the articles is lower than 300C (which is suitable for the handling and appearance thereof) and the solvent content upon opening is less than 100 parts per million.

As an example, the following table comparing various machines using perchlorethylene illustrates the advantage of the invention: A = Consumption B = Conventional machine treating 10 kg of garments per cycle.

C = Machine with refrigerated condenser treating 10 kg per cycle.

D = Machine according to the invention treating 10 kg per cycle.

A B C D Electricity 32 KwH 4.33 KwH 1.54 KwH Water 100 1. 96 1. 43 1.

Solvent 750 gr. 180 gr. 150 gr.

The machine illustrated in Figure 2 differs from that illustrated in Figure 1 as regards the situation of the auxiliary condenser 12 in the refrigerated circuit.

Although the condenser 12 is in series with the condenser 4 and upstream thereof in Figure 1, it is mounted in parallel in Figure 2, the valves 22 and 23 permitting the fluid leaving the compressor to be transmitted either through the condenser 4 (valve 22 open, valve 23 closed) or through the condenser 12 (valve 22 closed, valve 23 open). The passage from the first phase to the second phase is therefore effected by actuating the valves 22 and 23 as well as the admission of water 13. An auxiliary valve 24 can be provided to regulate the circulation of Freon (Registered Trade Mark) or other refrigerant and consequently the temperature of the evaporator 3.

In the second phase according to this embodiment, the condenser 4 is not supplied and the air passing through it is not heated and this lowers the sequence of temperatures in the air circuit.

The numerical data in the foregoing description relate to perchlorethylene, which is the most widely used solvent. Solvents with a boiling point which is not far removed from that of perchlorethylene also exist. If other solvents are used, the optimum temperatures for each phase as well as the characteristics of the refrigerant to be used can be determined by a few tests, the process and the machine of the invention being sufficiently flexible to permit this adaptation.

Although the process and the machine of the invention have been designed to permit the use of high boiling solvents, they can also be utilized with low boiling solvents.

Claims

1. A method for the treatment of articles using a solvent medium having a high boiling point, in which the solvent present in the articles at the end of the treatment is recovered by using a fan to circulate an air stream which traverses these articles in a basket, is charged with solvent and then passes through a cooling unit in order to condense the solvent, wherein the air circulates in a closed circuit and, upon leaving the basket, passes successively through an evaporator, and a condenser of a refrigerator which comprises, in the high pressure part of the refrigerant circuit downstream of the compressor, an auxiliary condenser supplied with water or air, the operation being carried out in two phases with a first phase in which the auxiliary condenser is not supplied with air or water and a second phase in which the auxiliary condenser is supplied with air or water in such a way that the drop in the temperature of the air entering the basket during the said second phase is of the order of at least 1 roc to 300C.

2. A method according to Claim 1, wherein the rise in temperature in the first phase is accelerated by using an auxiliary heater provided with thermostatic means which switch off the said heater after temperature adjustment, the operation of the said auxiliary heater also being switched off throughout the entire duration of the second phase.

3. A method according to Claim 2, wherein the said thermostatic means is adjusted to a temperature of at least approximately 500C at the inlet of the basket whereas the temperature of the evaporator is approximately OOC.

4. A method according to any one of the preceding claims, wherein the auxiliary condenser is supplied with water at ambient temperature.

5. A method according to any one of the preceding claims, wherein the auxiliary condenser is also used during the first phase as a safety device for regulating the temperature or the pressure of the high pressure circuit of the refrigerator by means of a valve controlled by the said temperature or the said pressure.

6. A method for the treatment of articles using a solvent medium, substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.

7. A machine for the treatment of articles using a solvent medium permitting the use of solvents having a high boiling point, comprising a rotatable basket for receiving the articles which are to be treated with the solvent, means including a fan for causing an airstream to traverse the basket and the articles contained, and a condenser for cooling this airstream as it leaves the basket, wherein the air is circulated in a closed circuit, the air passing through an evaporator of a refrigerator with means for recovering the solvent and then through a condenser of the said machine and thence being returned to the basket by a fan, an auxiliary condenser being mounted in the fluid circuit of the said refrigerator downstream of the compressor, and said auxiliary condenser being dimensioned so that it is capable of lowering the temperature of the air entering the basket by about 1 00C to 300C at least when it is started up, and means being provided for selectively interrupting the operation of the said auxiliary condenser in a first phase or for starting up the said auxiliary condenser in a second phase.

8. A machine according to Claim 7, wherein an auxiliary heater is located in the path of the circulation of air downstream of the condenser of the refrigerator, the said auxiliary heater being provided with means for thermostatic control and for disconnection so that it can be switched on only during a rise in temperature in the first phase and switched off after the said rise in temperature and during the entire second phase.

9. A machine according to Claim 7 or 8 wherein the auxiliary condenser is connected in series with the condenser of the refrigerator and is provided with means for ensuring the circulation of coolant during the second phase, the said means interrupting the said circulation during the first phase.

10. A machine according to Claim 7 or 8, characterised in that the auxiliary condenser is connected in parallel with the condenser of the refrigerator and valves are provided for causing the refrigerant under pressure to be passed at will either through the condenser situated in the air circuit during the first phase, or through the auxiliary condenser during the second phase.

11. A machine according to any one of Claims 7 to 10, wherein the auxiliary conden'ser is adapted for use during the first phase as a safety device for regulating the temperature or pressure of the high pressure circuit of the refrigerator by means of a valve controlled by the said temperature or the said pressure.

12. A machine for the treatment of articles using a solvent medium, substantially as herein described with reference to the accompanying drawings.