WO1995010653A1

WO1995010653A1 - Cleaning and drying apparatus for planar textile products

Info

Publication number: WO1995010653A1
Application number: PCT/FI1994/000463
Authority: WO
Inventors: Georg Liljestrand; Ralf Liljestrand
Original assignee: Georg Liljestrand; Ralf Liljestrand
Priority date: 1993-10-15
Filing date: 1994-10-14
Publication date: 1995-04-20
Also published as: FI934567A0; FI934567A; AU7815494A

Abstract

The present invention relates to a method and apparatus for cleaning and drying planar and flexible products (1), preferably rugs or carpets. In general, cleaning apparatuses are constructed so that the drying process is selected according to the heat-sensitivity of the product. The product can be dried in a tumble-drier, a drying cupboard, by means of electric contacting, or by steam or gas. However, the efficiency of these methods is very low. According to the present invention, a planar and flexible product (1) is fed on a conveyor (2) into a cleaning apparatus, where it is washed e.g. with brushes (3), rinsed, and pre-dried in a mangle (8). Thereafter the product is fed into a drier, where it is finally dried by causing the remaining moisture to evaporate by means of microwaves generated by a microwave unit (15), and the water vapour is carried away from the product.

Description

Cleaning and drying apparatus for planar textile products

The present invention relates to a method for cleaning and drying planar and flexible textile products, preferably rugs or carpets, said method com¬ prising feeding the product into a washer, where it is washed mechanically on at least one side, whereafter it is fed into a mangle, where most of the detergent solution is squeezed from the product, whereafter the product is rinsed and fed into a mangling unit, where it is pre-dried.

Cleaning apparatuses are generally constructed so that the drying process is selected according to the sensitivity of the product. The product can be dried in a tumble-drier or a drying cupboard, by means of electric contacting, or by steam or gas.

In a tumble-drier, laundry is dried in a drum during supply of warm air. The heated air binds the moisture contained in the laundry to itself and carries it out of the drum. The moist air is removed from the drum by a fan; alternatively, moisture is removed from the air by condensation, whereafter the air can be re¬ used. The process requires a considerable amount of heat, and it wears sensitive products mechanically. Moreover, the temperature rises towards the end of the drying process, because the water which cools down the air has largely evaporated. It may therefore be necessary to regulate the process by a separate thermostat. A drying cupboard operates in such a manner that the laundry to be dried is hung on racks in a stationary space, whereafter the space is closed, and the drying takes place during supply of warm air. The process and the problems relating to it are mainly the same as with a tumble-drier, except that the product to be dried is not subjected to mechanical stress.

Steam, gas and electricity can be used, for example, for heating a drying roll; however, on account of the energy consumed, the efficiency is very low.

If the product is sensitive to heat, it must be air-dried, i.e. hung on various racks in a well- ventilated, possibly mechanically heated, air- conditioned space. As can be seen, the prior art has, however, many drawbacks and defects. One of the biggest problems - and the problem on which the present invention concentrates - pertains to drying of a cleaned product. If the drying is carried out mechanically and supply of heat is employed in the process, large amounts of energy are required. The consumption of energy makes the drying expensive. On the other hand, it takes a long time to air-dry products; a lot of space is therefore required for the drying, as a large number of cleaned products are usually dried simultaneously. Moreover, the necessary facilities entail heavy investments.

One technique that has been known for rather a long time but not been employed to a great extent is to dry products by means of microwaves, i.e. electro- magnetic radiation with a frequency of 500 to 50,000 MHz. FI 77 320 discloses a method for drying wood by microwaves. GB 1 254 931, GB 2 042 703 and WO 82/02761 disclose various methods and apparatuses for stabilizing moisture or drying various products. GB 1 254 931 discloses an apparatus with a plurality of successive microwave and suction devices for stabilizing the moisture content of a product. GB 2 042 703 describes the drying of wet material in a specially- designed resonator; the apparatus is not provided with any moisture-removing mechanism and has a complicated structure. WO 82/02761 discloses a drying apparatus comprising a microwave unit connected to a spherical vessel. The wet material is dried after it has been subjected to pressure reduction in the sphere in which it has been placed. The pressure is reduced in order to obtain a lower boiling point for the water contained in the material and thus to facilitate the drying.

By means of the present invention, it is possible to avoid the problems relating to the drying apparatuses currently in use and to the patented micro¬ wave driers in the drying of planar and flexible products, such as rugs, carpets and other fabrics.

As the most significant drawbacks of a conven¬ tionally employed cleaning process are the energy costs associated with the drying, and the time required for the drying, the present invention is based on the idea of minimizing these drawbacks. At the same time, the construction of existing microwave driers has been con¬ siderably simplified and adapted for use in, for instance, a mobile drying unit.

The method according to the invention is char¬ acterized in that the product is finally dried by causing the remaining moisture to evaporate by means of microwaves, whereafter the water vapour is carried away from the product by an air-flow supplied through the product, said air-flow being produced by providing a pressure difference between the different sides of the product.

According to the present invention, the mechanical cleaning can comprise wetting the product with a detergent solution and thereafter cleaning it with rotating brushes. Alternatively, the cleaning can comprise spraying a detergent solution on the product under high pressure to remove impurities and rinse them out. Evaporation of the remaining moisture in a planar and flexible product which is porous is ensured by supplying an air-flow through the product; this is effected by providing a pressure difference between the upper and lower side of the product. If the product is impervious, the evaporation can be ensured by directing an air-flow with high pressure to the surface of the product, where it binds the evaporated moisture to itself and carries it away from the drier. An apparatus according to the present invention for cleaning and drying planar and flexible products comprises one or more conveyors for conveying a planar and flexible product through the apparatus, a pump for spraying a detergent solution through nozzles on the product (1), said detergent solution being drawn from a container located under the conveyor, a mangle for squeezing the detergent solution from the product, a high-pressure rinsing means driven by a pump for spray¬ ing rinsing water from a collecting container on the product through nozzles, a mangling unit for pre-drying the product, the rinsing water being recovered in a collecting container located under the conveyor, a drier, driven e.g. by magnetrons, and a receiver rack for the cleaned and dried product. The planar and flexible product is fed continu¬ ously through a drier in which microwaves, generated e.g. by magnetrons, make the water contained in the product to evaporate while an air-flow provided in the drier prevents the product itself from heating up by carrying the evaporated water away. The cooling air-flow is directed, as stated above, through the product when the product is porous, and towards and along the surface of the product when the product is impervious.

The drier according to the present invention comprises at least one magnetron installed in a perforated casing, a perforated conveyor, and a base. The casing is made of metal or is coated with metal on the inside to allow microwaves to be reflected. The perforations in the casing and conveyor must have a diameter smaller than 3 mm to prevent microwaves from escaping from the casing.

The conveyor is preferably a cloth or a wire.

In order to provide the necessary air-flow through the product, the drier comprises a suction table below the conveyor, and a space formed in the base of the drier; underpressure is formed in said space by a pump connected to the outlet for providing an air-flow through the planar and flexible product, whereby fresh air is drawn into the upper space through perforations in the casing. If the product is impervious, the upper space defined by the casing is provided with ventilation equipment comprising a high-pressure supply-air device and a fan for removing the moisture-ladened air.

The properties and characteristic features of the present invention are described more closely in the appended claims.

According to the invention, a planar and flexible product is cleaned by placing it on a conveyor and feeding it between two rotating brushes after it has been wet with a detergent solution which is pumped by a pump and sprayed on the product through nozzles provided above the conveyor. The detergent solution collected in the product is squeezed out in a mangle, and the solution flows down to a container below the conveyor. The same detergent solution can thus be circulated in the wash section.

The rinsing is carried out in the same way as the washing in the wash section. The main components in the rinse section are a pump and nozzles. It may be necessary to use two successive rinse sections to remove the detergent solution from the cleaned product. At the end of the rinse section, there is a mangle, which removes most of the water contained in the product.

The planar and flexible product is dried by heating the water (about 1.5 kg/m²) in the product by means of microwaves. The microwaves are absorbed by the water which is heated. The microwaves will not heat the product directly, as they are absorbed by a material which has a higher dielectric value. The dielectric value of water is 80, whereas that of the cleaned product such as a textile rug or a fabric is approxim¬ ately 10. To prevent the product from being heated up by the water, an air-flow is supplied through the product. The air-flow replaces the moisture-ladened air between the fibres with drier air. This speeds up the removal of water and cools down the product. Consequently, the rug does not lose its colours, and its fibres are not destroyed.

Technically, the drying is carried out by providing a microwave oven with magnetrons above a suction table. The suction table is made of perforated sheet metal, and it forms the bottom of the microwave oven. The diameter of the perforations is smaller than 3 mm. The microwaves will bounce back and forth in the space under the casing until they hit the water contained in the product to be dried and are absorbed. Underpressure is provided in the space under the suction table by means of a fan. The difference in the pressure below and above the product to be dried causes an air- flow through the product to carry the evaporated water away as soon as it has evaporated by the action of microwaves and before it heats up the product.

During the final drying, an air-flow can also be directed with high pressure diagonally towards the surface of the planar and flexible product. The space defined by the casing and the conveyor is, in this case, provided with ventilation equipment suitable for the purpose, comprising a high-pressure supply-air fan and a fan for removing the moisture-ladened air. The air which hits the products with high pressure cools down the product while also removing moisture from it.

In addition, the drying can be made more efficient by conducting the moisture-ladened air in the space under the casing, for example, to a heat pump known per se. In the heat pump, the moisture-ladened air is cooled down, whereby the moisture is condensed; thereafter the same heat pump can heat the air again before it is returned to the space under the casing.

In the tests conducted, the product was conveyed through the drier with a velocity of 0.1 m/min. The magnetron used for generating the microwaves had a power of 5.5 kW/m, and an underpressure of 300 mbar was provided in the space under the suction table.

Several significant advantages over the prior art are achieved with the apparatuses and methods described in the present application. The handling of products to be cleaned is very simple, as a large number of the routines have been automated. The cleaning and drying apparatus of the invention performs the entire process from the washing to the drying automatically.

The possibility of mobile operation improves the service provided for clients considerably. The invention allows rugs and carpets, in particular, to be cleaned easily and rapidly. The present invention also provides a new type of drying process in industries where a rapid and/or a less expensive drying process is desired for planar and flexible products. The invention reduces the operating costs of the drying process to 25 to 30% of the costs associated with the energy-consuming processes currently used.

In the following, the invention will be described in greater detail with reference to the accom¬ panying drawings, in which

Figure 1 is a cross-section of a cleaning and drying apparatus according to the invention,

Figure 2 is a cross-section of a drying apparatus according to the invention, provided with ventilation equipment, and

Figure 3 is a cross-section of a drying apparatus according to the invention, provided with a heat pump. The cleaning process begins by placing a planar and flexible product 1 on a conveyor 2, preferably a cloth or a wire, which runs through the entire cleaning and drying apparatus. The product is fed continuously into a washer, where it is at first wet with a detergent solution. Thereafter the product is conveyed to a mechanical washer, in this embodiment between two rotating brushes 8. The detergent liquid is pumped by a pump 6 from a container 4 below the conveyor 2 through piping 5 and sprayed on the product 1 through nozzles 7 provided above the conveyor 2. Most of the detergent solution which remains in the product after the mechan¬ ical washing is squeezed from the product in a mangle 8. The solution flows down to a container 4 located below the conveyor 2, whereafter the same detergent solution can be re-used in the wash section, to which it is pumped through piping 5, and so on.

In the case of sensitive products, for example, the cleaning can also be carried out by spraying a detergent solution under high pressure on the surface of the product. It is also possible to employ a combina¬ tion of rotating brushes and pressure cleaning.

The rinsing step corresponds to the washing step in the wash section. The main components in the rinse section are a pump 11 and nozzles 12, to which rinsing water is pumped through piping 10 from a container 9 located below the conveyor 2. The rinsing water can be circulated in the rinse section. At the end of the section, there is a mangle 13, in which most of the water contained in the product 1 is removed before the product is conveyed further to the drier. The water that is squeezed from the product in the mangle 13 is recovered in the container 9, from which it can be pumped again to the rinsing nozzles, as stated above. The planar and flexible product is finally dried by heating the water in the product so as to evaporate it. This takes place in a drier comprising a unit for generating microwaves 15, such as a magnetron, mounted on a perforated casing 16. The product is conveyed by the conveyor 2 over a suction table 17. The diameter of the perforations in the casing 16 and of the openings in the suction table is less than 3 mm to prevent microwaves from escaping from the radiation space 22. Under the casing 16, the product 1 is subjected to continuous radiation from the microwave unit 15. The microwaves are absorbed by the water contained in the product, as a result of which the water is heated and finally evaporated. In order to prevent the heated water or water vapour from heating up the product itself, underpressure is provided in the space 21 defined by the suction table 17 and the container 18. The underpressure is produced by a fan 20 mounted in an exhaust-air channel 19. The underpressure causes an air¬ flow between the space 22 above the product and the space 21 below the product. This air-flow replaces the moisture-ladened air in the product, between the fibres, with fresh, drier air drawn in through the perforations in the casing 16. The air-flow facilitates removal of water from the product and, at the same time, cools down the product. Fresh air can also be supplied via ventila¬ tion equipment 23, 24 or a heat pump 26, where the air can be heated. The suction table, ventilation equipment and heat pump are each used separately, but they can also be used in conjunction with each other. The dried product 1 is conveyed out of the cleaning apparatus and to a receiver rack 23 or the like, where the product can be packed for collection or transportation to the client.

The cleaning and drying apparatus can be connected to a mobile base, e.g. a motor vehicle, and be driven by a separate generator unit, which supplies the necessary energy to the apparatus. This allows the cleaning and drying apparatus to be taken to the client. The apparatus can also be taken to clients or areas with possible clients regularly, according to a timetable.

The invention is not limited to the embodiment described above, but several variations are possible within the inventive concept, which is described in the appended claims.

Claims

1. A method for cleaning and drying planar and flexible textile products (1), preferably rugs or carpets, said method comprising feeding the product (1) into a washer (3), where it is washed mechanically on at least one side, whereafter it is fed into a mangle (8), where most of the detergent solution is squeezed from the product (1), whereafter the product is rinsed and fed into a mangling unit (13), where it is pre- dried, c h a r a c t e r i z e d in that the product is finally dried by causing the remaining moisture to evaporate by means of microwaves, whereafter the water vapour is carried away from the product by an air-flow supplied through the product, said air-flow being produced by providing a pressure difference between the different sides of the product.

2. An apparatus for cleaning and drying planar and flexible textile products, preferably rugs or carpets, comprising at least one conveyor (2) for conveying the product (1) through the apparatus, a pump (6) for spraying a detergent solution through at least one nozzle (7) on the product, a mangle (8) for squeezing the detergent solution from the product, a rinsing means for rinsing the product, a mangling unit (13) for pre-drying the product, a drier, and a receiver rack (23) for the cleaned and dried product, c h a r ¬ a c t e r i z e d in that the drier of the apparatus comprises a device for generating microwaves, and means for providing a pressure difference between the different sides of the product.

3. An apparatus according to claim 2, c h a r - a c t e r i z e d in that it comprises a collecting container (4, 9) located below the conveyor (2) for recovering and recycling the detergent solution and rinsing water.

4. An apparatus according to claim 2 or 3, c h a r a c t e r i z e d in that it comprises a mobile base and is provided with process water tanks and is independent of external power supply.

5. A method for drying planar and flexible products, preferably rugs or carpets, continuously fed through a drier, c h a r a c t e r i z e d in that microwaves generated in the drier make the water in the product evaporate while an air-flow produced in the drier and supplied through the product carries away the evaporated water and cools down the product.

6. A method according to claim 5, c h a r a c - t e r i z e d in that a pressure difference of 100 to

1,000 mbar is provided between the different sides of the product (1) .

7. An apparatus for drying planar and flexible products, preferably rugs or carpets, c h a r a c - t e r i z e d in that it comprises at least one unit (15) mounted on a perforated casing (16) for generating microwaves, a perforated conveyor (2) for conveying the product (1) into and out of the space (22) defined by said casing (16), and a base.

8. An apparatus according to claim 7, c h a r - a c t e r i z e d in that below the conveyor (2), the apparatus comprises a base comprising a suction table (17), a container (18) and a space (21) defined by these, said space comprising an outlet provided with a fan for producing underpressure and thereby for producing an air-flow through the product (1).

9. An apparatus according to claim 7 or 8, c h a r a c t e r i z e d in that the upper space (22) defined by the casing (16) and the conveyor (2) comprises a heat pump (26) for further increasing the drying effect in such a manner that the air cooled in the heat pump (26) and dried as a result of condensation is returned to the space (22) under the casing (16) after being heated in same heat pump.