EP3635164A1

EP3635164A1 - Process and apparatus for washing fabrics

Info

Publication number: EP3635164A1
Application number: EP17732328.4A
Authority: EP
Inventors: Bruno Scortegagna
Original assignee: Lafer SpA
Current assignee: Lafer SpA
Priority date: 2017-06-05
Filing date: 2017-06-05
Publication date: 2020-04-15
Anticipated expiration: 2037-06-05
Also published as: EP3635164B1; WO2018224124A1

Abstract

A process for washing fabrics (12) using carbon dioxide provides to use at least two treatment chambers (14, 15) operating alternately, or in partly or totally overlapping washing cycle, and to carry out in each of the treatment chambers (14, 15) the washing of a fabric (12). The process also provides to recover and recirculate the carbon dioxide used in one treatment chamber (14 or 15) at the end of the washing of a fabric, and to feed it into the at least one other treatment chamber (15 or 14), transferring the carbon dioxide from one treatment chamber to the other (14, 15) by means of a carbon dioxide feed and/or recovery and recirculation circuit (16) that connects the two treatment chambers (14, 15) to each other.

Description

"PROCESS AND APPARATUS FOR WASHING FABRICS"

FIELD OF THE INVENTION

The present invention concerns a process and an apparatus for washing fabrics, usable in the industrial field for the production of textile products, whether they consist of textile fibers of the animal, plant, artificial, synthetic or mixed type.

More particularly, the invention concerns a washing process and apparatus which use carbon dioxide as the main washing fluid.

BACKGROUND OF THE INVENTION

In the industrial field of textile production, it is known to perform at least one washing treatment, for example upon completion of the work, or during one or more of the intermediate steps, to eliminate pollutant substances such as oils and fats present in them as working residues.

In the textile industry, one of the steps that precedes the dyeing and finishing of the fabrics is the cleansing/washing of the fabric, defined in the field by the English word "scouring". This step of the process is fundamental for the removal of oils and/or paraffins or other textile auxiliaries used during spinning and/or weaving.

If these substances are not properly removed, stains and non-uniform parts can be formed during the dyeing operations, which therefore require further dyeing passes with the corresponding use of very high quantities of water; in addition, during the heat- setting processes that follow immediately, said residual textile auxiliaries tend to cause problems with regard to emissions into the atmosphere.

The washing processes generally used, depending on the type of pollutant to be eliminated, usually use solvents, hydrocarbons and/or aqueous solutions containing particular soaping substances, detergents, wetting agents, surfactants or suchlike.

Washing processes that use water with detergents to facilitate the removal of pollutants have been widely used until now, despite having a very negative environmental impact. However, safety and environmental protection legislation is becoming increasingly restrictive, and therefore it is necessary to identify industrial washing processes that have minimal or no environmental impact.

It is therefore fundamental to use processes that, on the one hand, do not use pollutant substances for the environment, but on the other hand, ensure that oils are optimally removed from the fabric. At present, on an industrial level, a macro-distinction is identified between plants that treat fabrics discontinuously and plants that treat fabrics continuously.

In the first group we find systems that are comparable to large industrial washing machines that provide to treat the fabric (or garments) in batches with different systems such as:

- hydrocarbons (of which different types are available on the market);

- tetrachloroethylene or perchloroethylene;

- water combined with detergents, dispersants and various agents;

- carbon dioxide C0₂.

Such systems are generally equipped with recovery and recycling systems for the product used. The productivity of these plants is limited by the load capacity.

In the second group, i.e. plants that treat the fabric continuously, the fabric is collected in a roll or on trolleys, it is then unwound and inserted into the treatment unit and processed continuously. At the end of the treatment, the fabric is re-wound in a roll or deposited in layers.

The plants that work continuously are essentially divided into water washing systems and dry cleaning systems.

The former use large amounts of water and soaps, together with dispersing and wetting agents and surfactants to increase the effectiveness of the process. The processed fabric must then be dried, which implies considerable use of energy and consequent processing costs. Furthermore, the water used requires expensive purification plants for the recovery.

On the contrary, dry cleaning plants use tetrachloroethylene (perchloroethylene), which allows to treat the fabric from dry to dry: this chlorinated solvent, although it does have excellent solvent properties (high Kauri-Butanol (Kb) index = 90) and is compatible with all kinds of fabric, nevertheless has negative aspects related to its toxicity for aquatic environments and its suspected carcinogenicity. For these reasons, heavy regulatory limits have been set for the use of this substance, with a view to progressively eliminate its use.

The modern machines that use tetrachloroethylene are obligatorily subject to a series of measures intended to ensure the almost total distillation and recovery of the solvent used. A part of solvent, however, remains in the sludge to be disposed of, that is, in oils extracted from the fabric, causing it to be classified as "hazardous waste^*'. At present, there are no plants operating continuously that provide to use hydrocarbons or C0₂ to treat the fabrics. This limit is intrinsically linked to the physical-chemical properties of said substances.

In the first case, in fact, it would be necessary to use an expensive vacuum distillation system due to the low flammability values of the hydrocarbons. Furthermore, since these substances have low solvent power (Kauri-Butanol index values of about half, or less than perchloroethylene), the process times would be considerably lengthened, limiting productivity.

In the case of carbon dioxide, working conditions in the liquid state make it necessary to work at very high pressure values: in discontinuous machines values of around 50 bar or higher are mentioned. These conditions preclude the construction of a continuous plant at competitive costs on the market.

C0₂ has a variety of properties that make it particularly suitable for scouring/ washing fabrics.

Liquid carbon dioxide has a considerable solvent power, especially for apolar substances; these features allow to achieve and even improve the cleaning results obtained until now with the other known processes.

Carbon dioxide is a substance easily available on the market and at low cost since it is a residue of other production processes from which it can be suitably worked to be re- used.

In its liquid state, C0₂ has very low surface tension and viscosity values, which make C0₂ a very good wetting agent, able to remove from deep in the fabric even very viscous liquids, such as complex composition mineral oils, fluid oils of a hydrocarbon nature or paraffins.

Carbon dioxide has solvent potentiality in each of its physical states.

Given the regulatory approach that is increasingly directed toward the elimination of hazardous substances and the progressive elimination of water consumption, C0₂ proves to be the most appropriate solution for taking apolar auxiliary textiles into solution and removing them from the fabrics.

The C0₂ washing processes used in the state of the art are generally intended for installation in laundries, and provide to treat mainly garments by immersing them in a bath of liquid carbon dioxide inside a pressurized treatment chamber. Known washing processes generally operate at pressures around 50 bar or higher. Generally, the garments are inserted in an apparatus provided with a rack that rotates inside a drum, as in traditional washing machines.

On this subject the following documents are known:

US-A-4012194 describes a process for extracting and washing garments using liquid carbon dioxide in a closed chamber with a corresponding C0₂ recirculation/recovery system and filtration/expulsion of the oils.

US-A-5858022 describes the washing of finished articles into a rotating drum by means of a mixture of C0₂, water, surfactant and an organic co-solvent.

US-A-5904737 describes a method for washing garments which uses the different pressure conditions to recirculate the solvent in a system consisting of a main chamber in which the garments are washed, and a series of storage tanks connected to a compressor. C0₂ is injected inside the chamber with nozzles that contribute to create a mechanical action on the products to be dry cleaned.

US-A-5412958 describes the washing of finished garments in a chamber equipped with a rotating drum for separating and collecting the "dirt". The C0₂ used in the process is filtered and recovered.

One disadvantage of these processes is that, if industrial fabrics are inserted into said apparatuses, it is unlikely that they will be cleaned uniformly. In fact, said fabrics do not remain uniformly positioned in the bath during the entire washing cycle, and therefore some areas can be treated and cleaned better than others, resulting in consequent uneven washing or the presence of stains on the fabric.

Another disadvantage is the fact that there are obvious limits on the productivity of the process, dictated by discontinuous working conditions (batches).

There are also C0₂ washing applications on upstream processes, that is, directly on the fibers, before weaving.

US-B-6183521 provides to use supercritical C0₂ with pressures comprised between 90 and 350 bar and temperatures comprised between 40°C and 120°C. This process allows to improve the properties of strength and elongation of the fibers compared to traditional methods used for scouring.

It is also known how the recovery and distillation of the C0₂ used in the various machines can be obtained using different systems.

In this regard, EP-A-2098307 describes a distillation system for C0₂ dry-cleaning machines for garments, that is, it concerns small machines. This plant provides to distil the C0₂ used in the process in two steps: a first step carried out in a first distillation unit, in which most of the C0₂ is separated from the extracted substances, and a second step, performed in a second distillation unit, with the purpose of increasing the total efficiency of separation.

However, in the context of continuous treatment, the Japanese document JP-A- 2010180385 (JP'385) describes a continuous, high-pressure treatment on generic films. The treatment provides an unwinding and rewinding device of the treated product inside a chamber divided into two or more compartments with different operating conditions. One disadvantage of the state-of-the-art systems is that they only allow a partial recovery of the carbon dioxide used in a washing process. Furthermore, they provide to condense/liquefy the carbon dioxide in order to recover it, and therefore require to install high powers in the apparatuses and have high energy consumption.

Starting from the state of the art as described above, one purpose of the present invention is to obtain a process and an apparatus that allow to improve the efficiency of the process of washing fabrics with carbon dioxide, providing to use two or more treatment chambers that work at least partly alternating with each other, and to recirculate the carbon dioxide from one treatment chamber to the other without needing any phase change, so as to considerably reduce the electric power needed for recovery. In particular, one purpose is to supply a washing apparatus and a correlated process that allows to recirculate and regenerate continuously the carbon dioxide in gaseous form from one treatment chamber to the other without needing to condense it and make it liquid, hence without requiring in said step to use condensation and/or liquefaction members and tanks, thus reducing the energy consumption and the electrical power needed by the apparatuses in order to recover it.

Another purpose of the present invention is also to obtain a washing apparatus to perform a washing process on fabrics with carbon dioxide that allows to wash the fabrics uniformly, removing from them oils, fats and/or organic and inorganic contaminants, without using additives.

Another purpose of the present invention is to perfect a washing apparatus that allows to perform semi-continuously the washing of fabrics, so that it is possible to use carbon dioxide in its liquid state, but at the same time reducing the treatment times known in the state of the art.

Another purpose is to obtain the residual sludges containing oils, fats, etc., free from contaminants such as solvents, etc., so that said sludges can be disposed of as non- hazardous waste.

Another purpose is to provide a washing process that is of low environmental impact and is not polluting but at the same time is efficient and allows to obtain a good cleaning of the fabrics.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a process for washing fabrics according to the present invention provides to wash fabrics using carbon dioxide.

The washing process according to the invention comprises inserting a fabric to be washed into a treatment chamber, impregnating the fabric by spraying liquid carbon dioxide onto it, and immersing the fabric in a bath of liquid carbon dioxide, said immersion being possibly associated with a beating action to make the removal of the substances to be eliminated more efficient.

According to some embodiments, the method provides to draw in the fabric on a plurality of return and transport rollers, to immerse it in the bath of carbon dioxide downstream of an unwinding roller, and finally to wind the washed fabric on a winding roller.

The washing process according to the invention provides to wash the fabrics in at least two treatment chambers put at a defined pressure, operating alternately or in partly or totally overlapping washing cycle, and to recover and recirculate the carbon dioxide used to pressurize a treatment chamber to feed it into the at least one other treatment chamber, without any phase change of the carbon dioxide.

Advantageously, the process according to the invention provides to recover and recirculate the carbon dioxide between the treatment chambers through a suitable circuit formed by a plurality of lines of communication and comprising a plurality of interception valves which selectively allow to open/close the passage of the flow between the different lines of communication. According to some embodiments, the process provides to recover the carbon dioxide in the gaseous phase. According to further embodiments, the process provides to at least partly recover the carbon dioxide from a first treatment chamber, inside which a higher pressure is defined, in order to recirculate it in a second treatment chamber having a lower pressure inside, by making the flow of gaseous carbon dioxide flow through a first line of communication that directly connects the at least two treatment chambers to each other.

According to further embodiments, the process provides to pressurize the treatment chamber before starting the washing treatment on the fabric at a pressure comprised between about 10 and about 60 bar.

According to further embodiments, the process provides to bring the treatment chamber to a vacuum condition at the end of the treatment on the fabric, and at the end of the passage of the carbon dioxide into the other treatment chamber, allowing almost total recovery of the carbon dioxide.

Before opening the treatment chamber to allow unloading and loading of the fabric to be treated, the atmospheric pressure can be restored by inserting air through a dedicated branch of the circuit.

According to further embodiments, after the insertion of a new roll of fabric to be treated and after closure, the treatment chamber is cleared by a vacuum cycle before being pressurized in order to begin a new treatment cycle on the new roll of fabric.

The present invention also concerns an apparatus for washing fabrics comprising at least two treatment chambers, each suitable for washing a fabric using carbon dioxide as washing fluid, and a carbon dioxide feed and/or recovery and recirculation unit, which connects the at least two treatment chambers to each other.

According to some embodiments, each treatment chamber comprises at least two winding/unwinding rollers configured respectively to wind and unwind a roll of fabric, transferring it from one to the other, and a containment tank suitable to contain a liquid carbon dioxide bath in which the fabric can be made to transit during its passage from one to the other of the winding/unwinding rollers.

The washing apparatus according to the invention provides to position two or more treatment chambers in parallel, which can operate alternately, or in partly or totally overlapping washing cycle, in such a way as to increase the productivity of the process. In this way, while one treatment chamber is depressurized to allow to extract the roll of treated fabric, it is possible to pressurize another treatment chamber to simultaneously begin the washing process of a new roll of fabric. It is thus possible to obtain a "semi-continuous" treatment that can halve (in the case of two chambers) or more (in the case of a plurality of chambers) the working times.

According to some embodiments, the carbon dioxide feed and/or recovery and recirculation circuit comprises regulation means configured to allow a passage of carbon dioxide from one treatment chamber to another without requiring a phase change.

According to one aspect of the present invention, the regulation means are configured to regulate the temperature/pressure conditions so that the carbon dioxide is recovered and recirculated in gaseous form, without needing to pass to the liquid phase.

Since it is not necessary to condense/liquefy the C0₂ during the depressurization of the chamber where the fabric was treated and the simultaneous pressurization of the chamber where a new treatment is performed, the apparatus according to the invention has reduced energy consumption, and the total electrical power installed can be reduced. According to some embodiments, the carbon dioxide feed and/or recovery and recirculation circuit can continuously recover the C0₂ used in one treatment chamber and purify it so that it can be reused in a closed loop circuit in another treatment chamber.

According to some embodiments, the carbon dioxide feed and/or recovery and recirculation circuit comprises at least one first line of communication that directly connects the at least two treatment chambers to each other, allowing to balance the pressure between them.

According to further embodiments, the gaseous carbon dioxide recovery and recirculation circuit comprises at least one compression device selectively connectable to one and/or the other treatment chamber and/or to a suction device, and configured to define a desired pressure inside them.

According to further embodiments, the gaseous carbon dioxide recovery and recirculation circuit comprises at least one suction device selectively connectable to one and/or the other treatment chamber by means of respective lines of communication provided with valves and configured to suck in the gaseous carbon dioxide present in the treatment chambers so as to define a desired pressure inside them, in particular configured to define a vacuum condition inside them.

BRIEF DESCRIPTION OF THE DRAWINGS These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings where:

- fig. 1 is a schematic representation of a washing apparatus in accordance with embodiments described here;

- fig. 2 is a schematic representation of a treatment chamber of the washing apparatus in fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

We will now refer in detail to one embodiment of the invention, an example of which is shown in the attached drawings.

With reference to figs. 1 and 2, we describe a washing apparatus 10 usable in the field of textile production, for example for removing oils and/or paraffins or other textile auxiliaries, used during the spinning and/or weaving step.

The washing apparatus 10 according to the invention comprises at least two treatment chambers 14, 15, seen enlarged in fig. 2, inside which a roll of fabric 12 to be washed can be introduced.

By the term fabric 12, here and hereafter in the description, we mean fabrics generally consisting of textile fibers of the animal, plant, artificial, synthetic or mixed type.

The fabrics 12 can also be open fabrics, tubular fabrics, or fabrics folded longitudinally on themselves and sewn.

The washing apparatus 10 also comprises a recovery and recirculation circuit 16 of the washing fluid, in this case carbon dioxide (C0₂), which connects the at least two treatment chambers 14, 15 to each other.

According to some embodiments, each treatment chamber 14, 15 is provided with a liquid C0₂ entrance 17 disposed for example on a lateral wall of the treatment chamber 14, 15, and at least a liquid C0₂ exit 18a, 18b.

In particular, each treatment chamber 14, 15 is provided with a liquid C0₂ overflow exit during the treatment cycle 18a, and a liquid C0₂ discharge exit 18b that is activated at the end of the washing cycle to discharge the liquid C0₂ from the washing tank.

According to some embodiments, the liquid C0₂ exits 18a, 18b cooperate with a containing tank 22 disposed inside each treatment chamber 14, 15, suitable to contain a bath of liquid carbon dioxide in which the fabric 12 to be washed can be made to transit. The treatment chamber 14, 15 also comprises a gas aperture 19 through which the carbon dioxide in a gaseous state can transit.

According to some embodiments, the treatment chamber 14, 15 also comprises a gas balancing line communicating with an accumulation tank 36 of the liquid carbon dioxide.

According to some embodiments, each treatment chamber 14, 15 comprises at least one pair of winding/unwinding rollers 20a, 20b configured respectively to wind and unwind a roll of fabric 12 from one to the other.

In particular, the fabric 12 to be washed is wound onto a first unwinding roller 20a and drawn onto a second winding roller 20b.

According to possible solutions, the treatment chamber 14, 15 can comprise one or more return rollers 21 configured to define a travel for the fabric 12 inside the treatment chamber 14, 15 and to keep the fabric 12 stretched between one and the other winding/un winding rollers 20a, 20b.

Although fig. 2 shows one sense for the travel P from the unwinding roller 20a to the winding roller 20b, it can be provided that the winding/unwinding rollers 20a, 20b can be interchangeable, so that both can perform the function of winding or unwinding of the fabric 12, so that it is possible to invert the travel P of the fabric 12, unwinding it from the unwinding roller 20b and winding it onto the winding roller 20a.

According to some embodiments, delivery nozzles 24 can be provided inside the treatment chamber 14 (for example shown in fig. 2) which are associated with the liquid C0₂ entrance 17 and are configured to deliver carbon dioxide in liquid form onto the fabric 12 during the winding/unwinding thereof.

According to other embodiments, each treatment chamber 14, 15 can comprise inside it beating rollers 25, configured to beat the fabric 12 in the section of travel between one and the other of the winding/un winding rollers 20a, 20b, creating a mechanical beating action, so as to increase the movement of the fabric 12 itself and thus further promote the removal of the pollutant substances.

According to other variant embodiments, the treatment chamber 14 can also comprise further delivery nozzles (not shown), configured to deliver carbon dioxide in gaseous form onto the section of fabric 12 immersed in the bath of liquid carbon dioxide 23.

According to other embodiments, squeezer rollers 26 can be provided inside the treatment chamber 14, cooperating with one or more return rollers 21 to squeeze the fabric 12 in transit so as to remove from it most of the liquid carbon dioxide retained in its fibers.

According to some embodiments, the squeezer rollers 26 can be disposed in correspondence with the containing tank 22, to squeeze/compress the fabric 12 at exit from the liquid carbon dioxide bath 23 before immersing it into it again, or downstream of a winding/un winding roller 20a, 20b to squeeze/compress the fabric 12 before it is wound thereon.

According to other embodiments, the treatment chamber 14, 15 can also comprise a removal device 28 configured to heat the fabric 12 before winding it onto one of the winding/un winding rollers 20a, 20b at the end of the washing treatment in order to make the carbon dioxide retained in the fabric 12 gaseous, so as to remove it more efficiently by means of the feed and recirculation circuit 16.

According to some embodiments, the removal device 28 can be configured with a removal device acting through thermal action. For example, the removal device 28 can comprise a heated roller against which the fabric 12 can be made to pass.

According to further embodiments, the removal device 28 can comprise one or more heated plates.

According to possible solutions, the removal device 28 can comprise, or be connected to, heat generation means, for example steam generators, resistances, diathermic oil, hot water, infrared rays, ultrasounds, or other.

With reference to fig. 1, we will now describe in greater detail the recovery and recirculation circuit 16 of the carbon dioxide.

According to some embodiments, the recovery and recirculation circuit 16 comprises flow interception/regulation means V01-VN, configured to allow the passage of carbon dioxide from one of the treatment chambers 14, 15 to the other treatment chamber 15, 14 without requiring a phase change thereof.

According to some embodiments, the recovery and recirculation circuit 16 comprises a plurality of pipes and lines of communication and transit for the carbon dioxide, with which one or more regulation/interception valves V01-VN are associated.

The valves V01-VN can be opened or closed to alternately allow or prevent the passage of carbon dioxide into the respective pipe or the respective line of communication and possibly to regulate the flow rate of the carbon dioxide through them.

According to some embodiments, the recovery and recirculation circuit 16 comprises at least one first line of communication that directly connects the first treatment chamber 14 and the second treatment chamber 15 through respective dedicated lines connected by means of suitable attachments to the respective gas apertures 19 of the treatment chambers 14, 15.

According to some embodiments, the recovery and recirculation circuit 16 comprises pressure regulation means 30, 32.

According to some embodiments, the pressure regulation means comprise in particular a suction device 30, for example configured as a vacuum pump, and a compression device 32, for example configured as a dry compressor that is able to act effectively on carbon dioxide in the gaseous state.

The suction device 30 and compression device 32 can be selectively connected to each other and each is also selectively connectable to one and the other treatment chamber 14, 15.

According to some embodiments, the compression device 32 can be connected simultaneously to both the treatment chambers 14, 15 through a respective gas aperture 19 so as to receive the gaseous carbon dioxide from a first treatment chamber 14 or 15, and at the same time to introduce it into the second treatment chamber 15 or 14.

According to some embodiments, the recovery and recirculation circuit 16 also comprises a condenser device 34 which can be located downstream of the compression device 32 and configured to condense the gaseous carbon dioxide.

According to other embodiments, moreover, the condenser device 34 can be connected to the collection tank 36 into which the liquid carbon dioxide can be conveyed.

According to other embodiments, a circulation pump 38 can be provided between the collection tank 36 and the liquid C0₂ entrance 17 of each treatment chamber 14, 15 so as to feed into it the carbon dioxide at a certain pressure.

According to other embodiments, the apparatus 10 can also comprise cleaning means 42, 44, 46 configured to clean the carbon dioxide of impurities and pollutant substances that can be present in it at the end of the washing process.

According to some embodiments, thanks to the recovery and recirculation circuit 16, the apparatus 10 is able to recover substantially all the carbon dioxide used for each washing treatment of the fabrics 12 in one or the other treatment chamber 14, 15, obtaining only the oils and the substances extracted as waste to be eliminated.

In particular, the apparatus 10 allows to recover the carbon dioxide in liquid form through the liquid C0₂ exits 18a, 18b, and to recover the carbon dioxide in gaseous form through the gas aperture 19.

In this way, the washing apparatus 10 according to the invention therefore allows to perform a "semi-continuous" treatment of the fabric 12, that is, to perform a washing treatment on a first fabric 12 in a first treatment chamber 14 while at the same time the second treatment chamber 15 can be cleared of the previous washing cycle and/or loaded with a second roll of fabric 12 to be treated.

Embodiments described here also concern a washing process which provides to use at least two treatment chambers 14, 15 to wash in each of them a fabric 12 using carbon dioxide as a solvent, and to recover and recirculate the carbon dioxide from one treatment chamber 14 to the other 15, or vice versa, by means of the recirculation and recovery circuit 16, without passing through a phase change of the solvent.

In particular, the process provides to recirculate the carbon dioxide in gaseous form from one treatment chamber to the other 14, 15 without needing to condense it and make it liquid, so as to considerably reduce the power required for recovery.

Hereafter, by way of example, we will describe the washing process that provides to recover the carbon dioxide from the first treatment chamber 14 and recirculate it in the second treatment chamber 15, but it is understood that the inverse process can be carried out, recovering the carbon dioxide from the second treatment chamber 15 and recirculating it in the first treatment chamber 14. It is understood that if the carbon dioxide is recovered from the second treatment chamber 15 and recirculated in the first treatment chamber 14, the process provides to open/close the suitable interception means V01-VN depending on the configuration of the recovery and recirculation circuit 16 itself.

According to some embodiments, the treatment chambers 14, 15 can operate alternately, or in partly or totally overlapping washing cycles. According to some embodiments, the washing process comprises inserting a roll of fabric 12 into a treatment chamber 14, 15, which is drawn on a plurality of rollers 20a, 20b, 21, impregnating the fabric 12 by spraying liquid carbon dioxide onto it, immersing it into the liquid carbon dioxide bath 23, and optionally a beating action to accentuate the effectiveness of the treatment, followed by squeezing in order to mechanically remove the excess carbon dioxide, and finally winding it on a winding roller 20.

After the fabric 12 has been inserted and possibly drawn in, the treatment chamber 14, 15 is closed and pressurized, as explained in more detail hereafter.

According to some embodiments, when performing a washing treatment on the fabric 12, the pressure inside the treatment chamber 14, 15 can be comprised between about 10 and about 60 bar.

According to some embodiments, the washing treatment provides to perform at least one fabric washing cycle, defined by the complete unwinding/winding of the fabric 12 from one to the other of the winding/unwinding rollers 20a, 20b.

According to some embodiments, the number of washing cycles, that is, the number of times in which a fabric 12 is unwound/wound on the respective winding/unwinding rollers 20a, 20b, can be chosen depending on the type of fabric 12 and/or the type of pollutants to be removed.

According to some embodiments, at the end of washing treatment of a roll of fabric 12 inside a treatment chamber 14, 15, the process according to the invention provides to recover the gaseous carbon dioxide from the latter and transfer it to the other treatment chamber 15, 14 which has been previously loaded with a new roll of fabric 12 and possibly previously cleared with a high vacuum cycle.

The process of washing and recovery and recirculating of carbon dioxide according to the present invention can include a plurality of steps a) to j).

According to some embodiments, a first step a) is provided to balance the atmosphere, which provides to connect the first treatment chamber 14 and the second treatment chamber 15 directly. In this first step a), a first line of communication comprised in the recovery and recirculation circuit 16 puts the respective gas apertures 19 in communication.

According to some embodiments, described only by way of example, the first line of communication can be defined by opening valves V42, V47, V46, V45, V39 and V43 - Ir respectively.

According to some embodiments, at least one valve V46 can be of the type suitable to regulate the speed of flow of the carbon dioxide through the line.

According to some embodiments, in the first treatment chamber 14, after the washing of the fabric 12, the pressure can be comprised between 10 and 60 bar, while the pressure in the second treatment chamber 15 is much lower, preferably at a certain degree of vacuum.

When the first line of communication between the two treatment chambers 14, 15 is opened, the gaseous carbon dioxide tends to flow from the first treatment chamber 14, which has a higher pressure, to the second treatment chamber 15, with a lower pressure until a balance is reached between the pressures of the two chambers 14, 15.

Once the pressures are balanced, the process according to the invention can provide a second step b) which provides to close the respective valves V42, V47, V46, V45, V39 and V43, intercepting the first line of communication.

According to some embodiments, the process according to the invention provides a third step c) to depressurize the first treatment chamber 14 and at the same time to pressurize the second treatment chamber 15.

The third step c) provides in particular to connect the first treatment chamber 14 with the entrance of the compression device 32 and the exit of the compression device 32 with the second treatment chamber 15, by means of a second line of communication.

According to some embodiments, the second line of communication can be defined by opening valves V42, V38, V36, V25 respectively (thanks to which the first treatment chamber 14 is in communication with the compression device 32), and valves V24, V45, V39 and V43 (thanks to which the compression device 32 communicates with the second treatment chamber 15).

According to some embodiments, after opening the second line of communication in step c), the process according to the invention can provide a fourth step d) of activating the compression device 32 to suck up the gaseous carbon dioxide from the first treatment chamber 14 and introduce it into the second treatment chamber 15 until pressure values near to atmospheric pressure are reached in the first treatment chamber 14.

According to some embodiments, the process according to the invention can also comprise a fifth step e) of sucking up the residual carbon dioxide from the first treatment chamber 14 to a defined degree of vacuum.

According to possible solutions, the fifth step e) provides to connect the first treatment chamber 14 with the entrance of the suction device 30, the exit of the suction device 30 with the entrance of the compression device 32 and the compression device 32 with condenser device 34, opening respective valves to define a third line of communication.

According to some embodiments, the fifth step e) provides to perform three different operations e.i), e.ii) and e.iii).

A first operation e.i) provides to connect the first treatment chamber 14, the suction device 30, and the compression device 32, for example by opening respectively valves V44, V20 (between the first treatment chamber 14 and the suction device 30), V26 and V25 (between the suction device 30 and the compression device 32), and keeping valves V42, V38, already open in the third step c), in the open position to define said third line of communication.

A second operation e.ii) provides to close the connection between the compression device 32 and the second treatment chamber 15, for example by closing valves V24, V45, V39 and V43 respectively.

A third operation e.iii) provides to connect the compression device 32 to the condenser device 34, for example by opening valve V23, and the condenser device 34 to the collection tank 36 of the liquid carbon dioxide.

According to some embodiments, the process provides to perform operations e.i), e.ii) and e.iii) simultaneously.

According to further embodiments, the process provides to keep the recovery and recirculation circuit 16 in the configuration set in the fifth step e), and to keep the suction device 30, compression device 32 and condenser device 34 active until the desired degree of vacuum is reached in the first treatment chamber 14.

According to possible solutions, the degree of vacuum can be about 0.001 bar- absolute.

At the end of this fifth step e) the process according to the invention has advantageously completed the transfer and recovery of the carbon dioxide.

According to some embodiments, the process according to the invention provides a sixth step f) of intercepting all the lines of communication between the first treatment chamber 14 and the second treatment chamber 15 so as to perform the washing steps as described below.

According to some embodiments, after the sixth step f), the second treatment chamber 15 can begin the treatment cycle of the fabric 12 loaded therein, while the already washed fabric 12 can be removed from the first treatment chamber 14 which can be reloaded with a new roll of fabric 12.

To safely unload and reload the first treatment chamber 14, which has been taken to a certain degree of vacuum in the preceding fifth step e), the process according to the invention can provide a seventh step g) to restore atmospheric pressure in the first treatment chamber 14.

According to some embodiments, the seventh step g) can provide to connect an air introduction/discharge unit 40 to the gas aperture 19 of the first treatment chamber 14 by a fourth line of communication, for example defined by opening the respective valves V29, V36, V38, V42, and to introduce air inside the first treatment chamber 14 until atmospheric pressure is reached.

In this way it is possible to safely open a door of the first treatment chamber 14 so as to remove the already treated roll of fabric 12 and introduce a new roll of fabric 12 to be treated.

Once the new fabric 12 has been introduced and the first treatment chamber 14 has been closed, the process according to the invention can comprise an eighth step h) of clearing the first treatment chamber 14 by means of a vacuum cycle so as to eliminate the air present in it.

According to some embodiments, the eighth clearing step h) provides to connect the first treatment chamber 14 to the suction device 30 and the latter to the air introduction/discharge unit 40, opening respectively valves V42, V38, V44, V20, V27, and to suck in the air from the first treatment chamber 14 until the desired degree of vacuum is reached.

At the end of this step, the method provides to repeat steps a), b), c), d) as described above to pressurize the first treatment chamber 14, for example recovering the carbon dioxide from the second treatment chamber 15, or from a further treatment chamber, not shown.

Finally, when the first treatment chamber 14 is pressurized, the method according to the invention provides a ninth step i), in which the washing cycle of the fabric 12 is performed. According to some embodiments, the seventh step of restoring the atmospheric pressure g) and the eighth clearing step h) carried out in the first treatment chamber 14 can be performed simultaneously with the washing step j) carried out in the second treatment chamber 15.

According to some embodiments, the ninth washing step i) provides to activate the circulation pump 38 to supply the liquid C0₂ entrance 17 with liquid carbon dioxide until the containment tank 22 is sufficiently filled to allow the fluid to overflow from the containment tank 22 because the latter is too full.

Subsequently, the ninth washing step i) provides to unroll the fabric 12 from an unwinding roller 20a and simultaneously wind it onto a winding roller 20b, causing it to pass in the containment tank 22 in the liquid carbon dioxide bath.

During the unwinding/ winding of the fabric 12, the method also provides to drive the beating devices 25 in such a way as to beat the fabric 12 in transit and increase the removal effect of oils, fats and paraffins.

According to some embodiments, during the washing step i), for example carried out in the second treatment chamber 15, the process provides to open valve V02 located on a balancing line of the carbon dioxide in the gaseous state, valve V04 of the exit line of the liquid carbon dioxide through overflow, and valves V07, V08, VI 2, to feed the liquid C0₂ entrance 17 from the collection tank 36.

Furthermore, during the washing step i) the process can provide to connect the second treatment chamber 15 by means of the gas exit 19 to the condenser device 34 and the latter to the collection tank 36 of the liquid carbon dioxide, for example by opening the respective valves V43, V39, V37, V32 and V33.

According to further embodiments, the process according to the invention can comprise a further tenth j) step of cleaning the liquid carbon dioxide used during the washing cycle.

According to some embodiments, the cleaning of the liquid carbon dioxide can be carried out by distillation, to eliminate the substances taken into solution during washing (oils, fats, paraffins, etc.) by activating the evaporator device 42, the centrifugal oil separator 44 and the coalescing oil separator 46.

According to the embodiment shown by way of example in fig. 1, during the tenth cleaning step j) the process provides to open valves V08, V14, V16, V18, V30.

According to some embodiments, the tenth cleaning step j) can be carried out at the same time as the washing step i).

According to possible variants, the cleaning step j) can be carried out after the washing step i).

According to possible variant embodiments, the liquid carbon dioxide can be cleaned and regenerated by ultrafiltration.

According to other embodiments, the liquid carbon dioxide can be cleaned and regenerated in combination with or as an alternative to ultrafiltration, with other membrane technologies such as microfiltration, nanofiltration or reverse osmosis for example.

According to variant embodiments, the liquid carbon dioxide containing the pollutant substances can be distilled without using ultrafiltration.

It is understood that everything that has been described above with reference to steps a) to j) of the washing process according to the invention can be carried out in a specular fashion between the treatment chambers 14, 15. For example, in a specular manner to what is described above, according to some embodiments, the seventh step of restoring atmospheric pressure g) and the eighth clearing step h) can be carried out in the second treatment chamber 15 at the same time as the washing step j) carried out in the first treatment chamber 14.

It is clear that modifications and/or additions of parts can be made to the method for washing fabrics as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of method for washing fabrics, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

1. Process for washing fabrics (12) using carbon dioxide, characterized in that it provides to use at least two treatment chambers (14, 15) operating alternately, or in partly or totally overlapping washing cycle, and to carry out in each of said treatment chambers (14, 15) the washing of a fabric (12), wherein said process also provides to recover and recirculate the carbon dioxide used in one treatment chamber (14 or 15) at the end of the washing of a fabric, and to feed it into the at least one other treatment chamber (15 or 14), transferring the carbon dioxide from one treatment chamber to the other (14, 15) by means of a carbon dioxide feed and/or recovery and recirculation circuit (16) that connects said at least two treatment chambers (14, 15) to each other, wherein the temperature/pressure conditions of the carbon dioxide are regulated so as to allow a passage of the carbon dioxide in a gaseous form from one treatment chamber (14 or 15) to the other treatment chamber (15 or 14) without any phase change.

2. Washing process as in claim 1, characterized in that it provides to recover the carbon dioxide from one of said treatment chambers (14 or 15) having a greater pressure inside it than the pressure in the other treatment chamber (15 or 14) and to transfer it into the latter, making the flow of gaseous carbon dioxide flow through a first line of communication defined by opening one or more valves (V42, V47, V46, V45, V39, V43) and directly connecting the at least two treatment chambers (14, 15) with each other.

3. Washing process as in either claim 1 or 2, characterized in that said process provides to take said treatment chamber (14, 15) to a certain pressure comprised between about 10 and about 60 bar by means of a compression device (32) before beginning the washing treatment on the fabric (12).

4. Washing process as in any claim hereinbefore, characterized in that it provides to take said treatment chamber (14, 15) to a vacuum condition at the end of the washing operations of a roll of fabric (12) using a suction device (30) so as to clean it and clear it before beginning a treatment cycle on a new roll of fabric (12).

5. Washing process as in claim 2, characterized in that when a balanced position is reached between the pressures of said treatment chambers (14, 15), it provides to close said one or more valves (V42, V47, V46, V45, V39, V43) in order to intercept said first line of communication and to extract the residual carbon dioxide from one of said treatment chambers (14 or 15) by activating suction devices (30) and/or compression devices (32), so as to take the pressure inside it to values near to atmospheric pressure and at the same time to pressurize the other of said treatment chambers (15 or 14).

6. Washing process as in claim 5, characterized in that when the desired pressure is reached in said other treatment chamber (15 or 14), and/or at the end of the washing process, it provides to close the connection between said compression device (32) and said other treatment chamber (15 or 14) and to connect said compression device (32) both to a condenser device (34) and also to said suction device (30), which is in connection with a treatment chamber (14 or 15), until the desired vacuum pressure condition has been reached inside said treatment chamber (14 or 15).

7. Washing process as in any claim hereinbefore, characterized in that it comprises a cleaning step that provides to clean the carbon dioxide of impurities and polluting substances present therein at the end of the washing process by means of distillation, ultrafiltration or other membrane technologies.

8. Washing process as in any claim hereinbefore, characterized in that said washing cycle of the fabric (12) comprises inserting a roll of fabric (12) into a treatment chamber (14, 15), drawn onto a plurality of rollers (20a, 20b, 21), and impregnating said fabric (12) by spraying liquid carbon dioxide onto it, immersing it in a bath of liquid carbon dioxide (23), and a mechanical beating action on it during the winding/un winding of said fabric (12) on said rollers (20a, 20b, 21).

9. Apparatus for washing fabrics (12), characterized in that it comprises at least two treatment chambers (14, 15) operating alternately, or in partly or totally overlapping washing cycle, and a carbon dioxide feed and/or recovery and recirculation circuit (16) that connects said at least two treatment chambers (14, 15) to each other, wherein said feed circuit (16) comprises interception means (V42, V47, V46, V45, V39, V43) and pressure regulation means (30, 32) configured to regulate the temperature/pressure conditions of the carbon dioxide so as to allow a passage of the carbon dioxide in gaseous from one treatment chamber (14 or 15) to the other (15 or 14) without any phase change.

10. Washing apparatus as in claim 9, characterized in that said carbon dioxide feed and/or recovery and recirculation circuit (16) comprises at least a first line of communication, defined by opening one or more valves (V42, V47, V46, V45, V39, V43), which directly connects the at least two treatment chambers (14, 15) to each other, allowing a balance of the pressure between them.

1 1. Washing apparatus as in claim 9 or 10, characterized in that said pressure regulation means comprise at least one suction device (30) selectively connectable to one and/or the other treatment chamber (14, 15), and configured to suck in the gaseous carbon dioxide present in the treatment chambers (14, 15), in order to define a desired pressure inside them, and a compression device (32), selectively connectable to one and/or the other treatment chamber (14, 15) and/or to said suction device (30).

12. Washing apparatus as in any of the claims from 9 to 1 1, characterized in that each treatment chamber (14, 15) comprises at least two winding/unwinding rollers (20a, 20b) configured respectively to wind and unwind a roll of fabric (12) from one to the other, and a containing tank (22) suitable to contain a bath of liquid carbon dioxide (23) in which the fabric (12) can be made to transit during its passage from one to the other of the winding/un winding rollers (20a, 20b).