EP0022027B1 - Process for extracting a fabric-impregnating solvent and apparatus for carrying it out - Google Patents

Description

The present invention relates to a process for extracting an impregnating solvent from fabrics, in particular after dry cleaning of these fabrics in the dyeing industry.

It also relates to a device for implementing this method.

• a. dans une première phase, dite phase d'évaporation, on échauffe l'air par un apport de chaleur à une température comprise entre environ 60°C et 100°C, avant de l'injecter dans les tissus, et on le refroidit à sa sortie en le faisant passer sur une surface dont la température est voisine de 0°C pour récupérer le solvant extrait des tissus par l'air chaud;
• b. dans une seconde phase, dite phase de désodorisation, on refroidit l'air sortant des tissus en le faisant passer sur cette même surface dont la température est alors maintenue à environ -20°C, en supprimant l'apport de chaleur, de manière à éliminer les dernières traces de solvant présentes dans les tissus.

It is known, in particular from FR-A-2 325 758, to carry out this extraction by circulating hot air in these fabrics to evaporate the solvent, by cooling this air to condense the solvent vapors, and by reinjecting in a closed circuit into the tissues after reheating. The following operations are carried out successively:

• at. in a first phase, called the evaporation phase, the air is heated by adding heat to a temperature between about 60 ° C and 100 ° C, before injecting it into the tissues, and it is cooled to its exit by passing it over a surface the temperature of which is close to 0 ° C. to recover the solvent extracted from the tissues by hot air;
• b. in a second phase, called the deodorization phase, the air leaving the tissues is cooled by passing it over this same surface, the temperature of which is then maintained at approximately -20 ° C., by suppressing the supply of heat, so as to remove the last traces of solvent present in the tissues.

This same document provides for using the evaporator of a thermodynamic machine as a cooling surface. The adaptation of the degree of cooling according to the envisaged phase is carried out by modifying the pressure upstream of the expansion member of said machine, which leads to a relatively complex and delicate mechanical production of this machine.

On the other hand, from document US-A-3,791,160, a method of air conditioning for residential premises is known, in which air is cooled by means of a refrigerating machine, and in which regulates the air temperature by injecting into the expanded refrigerant a certain flow of hot compressed fluid which bypasses the expansion valve. This flow rate is regulated by a servo valve controlled by a room thermostat.

Adapting such a process to dry cleaning machines would only lead to regulating the temperature of the air blown into the fabrics. However, the problem of the invention is different and essentially aims to prevent icing of the cooling battery during the first phase of the operation where the air is heavily charged with moisture.

The object of the invention is to provide a method and a device which makes it possible to regulate the cooling phenomenon in a manner strictly necessary and sufficient to prevent this icing.

This object is achieved, in accordance with a first aspect of the invention, by injecting into the expanded refrigerant admitted for evaporation a predetermined flow rate of gaseous hot fluid controlled by the temperature of the evaporated fluid.

By doing so, the temperature of the evaporator itself is precisely regulated, which makes it possible to avoid icing under the most rational conditions.

According to a second aspect of the invention, the device for extracting a solvent impregnating fabrics after dry cleaning, and in particular for applying the aforementioned method, comprises an air circulation corridor mounted in closed circuit on a cleaning drum. A cooling battery and a heating battery are connected in series in this corridor and a condensate recovery point is provided between these two batteries. The cooling coil is the evaporator of a thermodynamic machine and this device is characterized in that the circuit of the thermodynamic machine comprises a bypass connecting the piping of hot gaseous fluid to the piping of expanded fluid upstream of the evaporator, this bypass comprising a servo valve connected to a temperature detector located on the fluid piping leaving the evaporator, to maintain the temperature of said evaporator in a predetermined band.

Other features and advantages of the invention will emerge from the detailed description which follows.

• - la Figure 1 est une vue schématique d'une machine de nettoyage utilisant un procédé conforme à l'invention dans une première réalisation,
• - la Figure 2 est un schéma du circuit frigorifique correspondant à cette réalisation,
• - la Figure 3 est une vue schématique d'une machine de nettoyage utilisant un procédé conforme à l'invention dans une seconde réalisation,
• - la Figure 4 est une schéma de la machine frigorifique correspondant à cette seconde réalisation.

In the appended drawings, given by way of nonlimiting examples:

• FIG. 1 is a schematic view of a cleaning machine using a method according to the invention in a first embodiment,
• - Figure 2 is a diagram of the refrigeration circuit corresponding to this embodiment,
• FIG. 3 is a schematic view of a cleaning machine using a method according to the invention in a second embodiment,
• - Figure 4 is a diagram of the refrigerating machine corresponding to this second embodiment.

Referring to Figures 1 and 2, a dry cleaning machine for clothes comprises a drum 1 provided with stirring means not shown, on which is mounted in a closed circuit a corridor 2 for air circulation, com carrying a fan 3 which causes this circulation in the general direction of the arrows.

In the corridor 2 are mounted in series a cold battery 4 constituted by the evaporator of a refrigerating machine and a heating battery 5 providing external thermal energy to the system. In the example described, this battery operates with steam.

Between these two batteries is formed a low point 6 from which a pipe 7 provided with a control light 8 to a tank 9 for separating immiscible liquid phases.

A buffer 11 controlled by a jack 12 can be lowered to cooperate with a bearing 13 and isolate the heating battery 5. A control device not shown allows, simultaneously, to actuate a jack 14 associated with a pad 15 to open a corridor of bypass 2a and force the air to circulate according to the arrows F1.

An air filter 16 is arranged in the corridor 2 to retain solid impurities from the clothes.

The tank 9 comprises a vertical partition 17 not going down to the bottom and delimiting two compartments 9a, 9b, the pipe 7 opening at the bottom of the compartment 9a. Two vertical tubes 18a, 18b are housed in the respective compartments 9a, 9b and open out at different heights. The tube 9a is connected to a tank 19 for recovering water and the tube 9b, which opens lower than the tube 9a, is connected to a circuit (not shown) for solvent recovery.

We will now describe in detail, with reference to FIG. 2, the refrigeration circuit to which the evaporator 4 belongs.

The circuit includes a compressor 21 discharging the gaseous refrigerant in a line 22 leading to a condenser 23 cooled by a water circuit 24. This water circuit is provided with a servo-valve 25 connected to a temperature sensor 26 which measures the temperature of the fluid arriving at the condenser 23 to control the flow of cooling water to this temperature in order to obtain substantially constant cooling of the condenser.

The condenser opens into a line 27 in which a desiccant filter 28, a solenoid valve 29, and a control lamp 31 are mounted in series.

Line 27 finally arrives at the evaporator 4 via a pressure regulator 32 controlled by the pressure prevailing downstream in a line 33 returning to the compressor 21. A pressure regulating valve 34 is mounted on line 33.

The refrigeration circuit also comprises a pipe 35 mounted as a bypass and directly connecting the pipe 22 to the pipe 27 between the expansion valve 32 and the evaporator 4. On the pipe 35 are mounted a solenoid valve 36 and a servo-valve 37 connected to a sensor 38 of the temperature of the refrigerant leaving the evaporator, so as to open when this temperature tends to drop.

We will now describe the operation of this apparatus, which will serve as a description of the process.

The clothes placed in the drum 1 having been cleaned by stirring in a solvent which is generally perchlorethylene, the drum is emptied, it is wrung, but the clothes remain impregnated with solvent.

The fan 3 is started, the buffers 11 and 15 being in the position indicated in FIG. 1. In addition, the compressor 21 is started, the solenoid valve 36 being open.

The air is circulated in the corridor 2 according to the arrows, passing through the heating battery 5 where it heats up to a temperature between 60 ° and 70 ° C before entering the drum 1 where it evaporates a part of the solvent permeating clothing.

It then leaves through the filter 16 and passes through the evaporator 4 where it cools, which causes the condensation of the water and solvent vapors which it contains and which are collected in liquid form at the low point 6, where they are brought via line 7 to the separation tank 9.

In this tank, the lighter water rises to the surface of the compartment 9a from which it flows by overflow effect into the tube 18a. The heavier solvent passes into compartment 9b from which it flows in the same way through the tube 18b.

The servo valve 37 admits sufficient coolant leaving the compressor 21 at the inlet of the evaporator 4 so that the surface of the latter is not at a temperature below 0 ° C or above 5 ° C , so that water vapor icing is avoided.

The duration of this evaporation phase is variable depending on the amount of solvent to be evaporated, but, in the usual cleaning machines, it is between 6 and 16 minutes. It is considered complete when about 90% of the solvent which has permeated the clothes has been evaporated after emptying.

The clothes are then warm and crumpled, and it is still necessary to extract a certain amount of solvent to deodorize them.

The buffers 11 and 15 are then operated by the jacks 12 and 14, so as to isolate the heating coil 5, the air passing along the arrows F1. At the same time, the solenoid valve 36 is closed, so that the refrigerant leaving the expansion valve 32 is no longer heated by mixing and the surface temperature of the evaporator 4 is between -15 ° C and -25 °. C, preferably at -18 ° C.

This vigorous cooling causes a more efficient condensation of the solvent vapors which have become rarer, without however causing icing, because at this instant, any the water disappeared by condensation during the previous phase.

The air passing through the evaporator cools mainly in its boundary layer, but not in its entire mass. Leaving the evaporator 4, it still partially heats up in contact with the hot metallic masses of the machine, and especially in contact with the clothing it cools. Despite its gradual cooling, its evaporative power remains high due to its great dryness obtained by the above-mentioned vigorous cooling.

After 8 to 12 minutes, the clothes are suitably cooled, de-crumpled and deodorized, containing practically no more solvent. The operation is therefore finished.

The application of the method therefore makes it possible to obtain these excellent performances in a simple manner, while procuring a notable operating economy on the consumption of cooling water, due to the fact that, the condenser being at a temperature clearly. higher than that of the air to be cooled, it is possible, by exchange, to bring the water to a markedly higher temperature and thus reduce its flow rate. For example, water, instead of going out at 25 ° C, can go out at 40 ° C.

We will now describe, with reference to Figures 3 and 4, another embodiment of the method, with an alternative embodiment of the device.

In this description, the elements identical or equivalent to those of the embodiment described above will bear the same reference numbers and will not give rise to description. If necessary, reference may be made to what has been said above.

Referring to Figures 3 and 4, the cleaning machine is constituted substantially in the same way as in the previous embodiment, except that a bypass 2b is formed in parallel with the evaporator 4 in the corridor 2, this bypass being closable by a buffer 41 actuated by a jack 42.

In addition, instead of the heating coil 5, an additional condenser 43 is placed on the air path, incorporated in the refrigeration circuit mounted in parallel with the condenser 23 and switchable with it, by a set of valves 44, 45, the valve 44 supplying the condenser 23, and the valve 45 supplying the condenser 43.

A servo valve 46, controlled by the upstream pressure, is mounted at the outlet of the condenser 43. This condenser is provided with a bypass 47 provided with a servo valve 48 which closes when the pressure difference between its inlet and its outlet tends to increase.

During the first phase, called the evaporation phase, the valve 45 is open and the valve 44 is closed. At the start of the phase, the valve 48 is open and the valve 46 is closed. Then, the pressure rising in the condenser 43, the valve 46 opens and the valve 48 closes. It follows that the condenser 43 is in service, serving as a heating battery, and that the condenser 23 is off, allowing the flow of cooling water to stop.

Of course, during this evaporation phase, the bypass 35 is opened to ensure that the surface temperature of the evaporator 4 does not fall below 0 ° C, as explained above.

When we pass to the second phase, called deodorization, we close the valve 45, which isolates the condenser 43 while maintaining it under pressure, and we open the valve 44, which activates the condenser 23 in which we restores the cooling water flow. Closure 35 is also closed by valve 36.

The heating battery being out of service, the deodorization process continues as in the previous embodiment. However, in order to facilitate the cooling of the surface of the evaporator 4 down to -18 ° C., the bypass 2b is opened by opening the buffer 41 by the jack 42, so that part of the air is bypassed according to arrow F2. The evaporator, seeing only about half of the air flow passing, cools more easily, which allows the solvent vapors to condense more efficiently. This bypass, necessary for the phase flow, can advantageously be maintained until the end.

This embodiment has the advantage over the previous one that the heat recovered by cooling the air is used, in the first phase, for heating. Not only does it save cooling water, but it also saves the supply of external thermal energy for heating.

Of course, the invention is not limited to the examples described, but also covers, within the scope of the claims, any minor variant in the process as in the device, which can also be used for different applications.

Claims (14)

1. A process for the extraction of a solvent impregnating fabrics, in particular clothes after dry-cleaning, which consists in circulating warm air through these fabrics so as to evaporate the solvent, in cooling the air so as to condense the solvent fumes, and in reinjecting it in a closed circuit into the fabrics after heating, in which the following operations are carried out in sequence:

a) in a first phase, called evaporation phase, the air is heated by a supply of heat to a temperature between 60°C and 70°C, before injecting it into the fabrics, and it is cooled on exit by passing it over a surface (4) the temperature of which is between 0°C and +5°C;

b) in a second phase, called deodorization phase, the air leaving the fabrics is cooled by passing it over aforesaid surface (4) the temperature of which is then maintained between -15°C and -24°C, and the heat supply is discontinued;

and in which the air cooling-surface (4) is itself cooled by the evaporation of refrigerating fluid in a thermodynamic machine, characterized in that in the first phase, cooling is achieved by injecting a predetermined flow of warm gaseous refrigerating fluid into the expanded refrigerated fluid admitted for evaporation, said flow being adjusted to the temperature of the evaporated fluid.

2. A process as claimed in claim 1, characterized in that the duration of the evaporation phase is between 6 and 16 minutes.

3. A process as claimed in one of claims 1 or 2, characterized in that the duration of the deodorization phase is between 8 and 12 minutes.

4. A process as claimed in one of claims 1 to 3, characterized in that, at least in the second phase, the heat produced by the machine is discharged by means of a flow of water.

5. A process as claimed in claim 4, characterized in that the water flow is adjusted to the temperature of the warm fluid.

6. A process as claimed in one of claims 1 to 5, characterized in that, in the first phase, the air is heated by the condensation heat from the refrigerating fluid.

7. A process as claimed in claim 6, characterized in that, in the second phase, only a part of the air flow is cooled, the other part being deviated then reinjected into the cooled flow.

8. A device for extracting a solvent impregnating fabrics after dry-cleaning, and in particular for implementing a process as claimed in claim 1, comprising an air-flow passage (2) assembled in a closed circuit on a cleaning drum (1), a cooling battery (4) and a heating battery (5, 43) which are aligned in said passage with a point (7) for recovering the condensates fitted between the two batteries, in which the cooling battery (4) acts as the evaporator of a thermodynamic machine, characterized in that the circuit of the thermodynamic machine comprises a bypass (35) connecting the warm gaseous fluid pipe (22) to the expanded fluid pipe upstream of the evaporator (4), this by-pass comprising a servo-valve (37) connected to a temperature sensor (38) situated in the pipe (33) for the fluid leaving the evaporator, in order to hold the temperature of said evaporator within a predetermined range.

9. A device as claimed in claim 8, characterized in that the by-pass (35) comprises a check valve (36) to discontinue the operation.

10. A device as claimed in one of the claims 8 or 9, characterized in that the thermodynamic machine comprises at least one condenser (23) placed in a cooling fluid circuit (24).

11. A device as claimed in claim 10 characterized in that the cooling fluid circuit comprises a servo-valve (25) connected to a sensor (26) placed in the refrigerating fluid circuit in the condenser (23).

12. A device as claimed in one of claims 10 or 11, characterized in that the thermodynamic machine comprises a second condenser (43) assembled in parallel with the first and interchangeable therewith by means of a set of valves (44, 45), said second condenser being situated in the air-flow passage (2) in order to form the heating battery.

13. A device as claimed in claim 12, characterized in that the thermodynamic machine comprises a servo-valve (46) downstream of the second condenser (43), adjusted to the pressure in said condenser.

14. A device as claimed in claim 13, characterized in that it includes a by-pass (47) in parallel with the second condenser (43) and, fitted with a servo-valve (48) tending to close when the pressure difference between its input and its output tends to increase.

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