GB2272227A - Injecting steam into soak baths of towel cleaning apparatus - Google Patents

Abstract

Cabinet towels are cleaned by passing them through a soak bath 21 and under a washer 25. The soak bath is preferably filled with hot water preferably discharged from the washers. To increase the temperature of the soak bath, steam is injected via steam injector 35. In a soak tank comprising an entry chute 22, an exit chute 24 and a linking section 23, a steam injection chamber 30 is created by perforating the upper wall 26 of the linking section, and bridging the space between the entry and exit chutes with a new upper wall and sidewalls. Water from the soak bath enters the chamber 30 via the perforated upper wall and is heated by steam injector 35. The temperature of the soak bath may be controlled by use of electrical controls. The width of entry chute 22 may be increased to give larger towel folds to increase the residence time of the towel in the tank. <IMAGE>

Description

CLEANING TOWELS This invention is concerned with improvements in the cleaning of towels.

A common sight in washrooms is a cabinet towel in which the user pulls down a fresh length of towel from a supply roll on an upper roller and the soiled towel is taken up on a lower roller. When the upper roll is exhausted it is replaced by a fresh roll and the roll of soiled towel is removed for washing.

Soiled towels are washed in an apparatus which unrolls the towels, passes the fabric strip through a pre-wash soaking tank, then to a wash by spray of hot water and detergent, to a rinse with water sprays followed by squeeze rollers, then over steam heated rollers for drying, followed by rewinding to form rolls of fresh towels. The wash water is steam heated. The same water is fed to the pre-soak tank, which is therefore at a lower temperature.

Normally successive towels are sewn end to end for continuous processing and the dry towels are held in accumulators to provide a production buffer before the soak (soiled towels) and before rewinding (cleaned towels).

Changes in hygiene regulations require that the pre-wash soak stage allows a longer soaking than hitherto and at higher temperatures. There is a need to achieve this by adapting existing apparatus to avoid undesirable waste of already invested capital.

Conventionally the pre-wash soak takes place in a so-called "J-tank" or "J-box" as shown in Fig. 1 of the accompanying drawings. The soak tank is functionally a U-tube with soak water extending up both limbs of the tube. The towel is fed into one limb of the soak tank, preferably provided as an inclined chute, passes around the linking bend, and exits the soak tank via the other limb, which may also be inclined but more preferably is a vertical chute. The section linking the entry and exit chutes is usually smoothly curved, to avoid snagging the towels. The towel is allowed to accumulate in folds and loops in the entry chute and/or the linking section and this increases the residence time in the soak. The aqueous detergent in the bath is derived from the circulation of the subsequent spray-wash stage.

The present invention achieves high soak temperatures by injecting steam into the pre-wash soak bath.

According to the present invention there is provided a method of cleaning towel rolls which comprises unrolling the towel and soaking it prior to washing, rinsing, drying and rewinding characterised in that during soaking of the towel in a bath of aqueous detergent, the bath is heated by injecting steam. Preferably the steam is introduced by a bellows type steam injector, and is usually controlled by temperature sensors and a timer.

To ensure satisfactory circulation of the heated water and avoid damaging adjacent towel loops, the steam injector is preferably isolated from the towel by a porous screen, for example mesh or perforated metal. The screen allows heated water to circulate from the vicinity of the steam injector to other parts of the bath without being impeded by adjacent loops of towel. Alternatively the steam injector may be placed in a separate chamber in communication with the liquid contents of the soak bath.

For adapting existing cleaning systems for use in the above process, the invention also provides a soak bath unit comprising an entry chute, an exit chute and an intermediate linking section and in which a chamber having a steam injector is provided in communication with the interior of the soak tank so that water in the soak tank can enter the chamber and receive steam injection.

In one embodiment of the invention the chamber is an external chamber having access to the interior of the soak tank through an aperture or apertures in the wall of the soak tank.

In another embodiment, the chamber is formed in the interior of the soak tank and comprises a steam injector and a porous screen separating the region surrounding the steam injector from the region through which in use the towel must pass.

Relative to the soak bath of the prior art, a soak bath provided in accordance with this invention preferably has a linking section of increased height to accommodate the steam injector, if provided interiorly. The steam injector allows the attainment of a higher temperature for the pre-wash soak.

Preferably, a soak bath in accordance with this invention also has an entry chute of increased width (in the direction of movement of the towel) relative to the prior art. This allows larger towel folds to form and thus increases the residence time of the towel in the tank.

For adapting existing apparatus, the soak tank of the prior art may be retained, and a steam injection chamber attached to communicate with the interior of the tank.

In one adaptation, perforations are provided in the original upper wall of the section linking the entry and exit chutes, and additional upper and sidewalls are provided to close the space between the entry and exit chutes, so as to form, with the perforated wall, a steam-injection chamber communicating via the perforations with the original tank.

In an alternative adaptation, a steam chamber is attached externally to a wall of the soak tank, and the wall of the tank is apertured to allow steam and heated water to circulate between the chamber and the tank. An existing soak tank may conveniently be adapted to this arrangement by removing an existing inspection plate, and attaching an external steam chamber, preferably via a perforated wall portion, to cover the inspection aperture.

The invention is described further below, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic cross-section through a prior art Jtank, Fig. 2 is a schematic cross-section through a J-tank adapted in accordance with the invention.

Fig. 3 is a schematic perspective view of the J-tank shown in Fig 2.

Fig. 4 is a schematic cross-section of a J-tank adapted in accordance with an alternative embodiment of the invention.

Fig. 5 shows a steam chamber for use in the apparatus shown in Fig. 4.

Referring to Fig. 1. a towel A is fed from a conventional unwinding section (not shown) to a soak tank (J-tank) 1. The tank 1 includes an entry chute 2 linked by an arcuate section 3 to an exit chute 4. The entry chute is preferably inclined so that a greater horizontal cross-sectional area is available to build up towel folds. The exit chute is preferably vertical so that the towel can be removed without dragging over the chute walls or lip. The tank is maintained in the upright position shown by a support framework, which is omitted for clarity.

On leaving the tank 1, the towel passes through a spray-wash section 5 and then on to conventional rinse, dry and rewind sections (not shown). The spray wash uses steam-heated aqueous detergent which, with appropriate filtration recirculates to the heater via the soak tank 1.

The towel A is fed into the entry chute 2 at a rate which initially is greater than the rate of removal (or without removal) from exit chute 4, so that the towel accumulates in folds in the chute 2 and at its base. After an appropriate residence time in the hot detergent solution, the towel is drawn through the linking section 3 and exits via the chute 4, for transfer on to the other processing steps. When the loops have piled up to an extent which corresponds to the desired residence time, the rate of feed and removal can be equalised.

Figures 2 and 3 illustrate the modification of an soak-tank of the type shown in Fig. 1, in accordance with this invention . The parts 21-25 have the same function as the parts 1-5 of Fig. 1, and a towel B is fed into the tank and processed substantially as described for towel A. The upper wall 26 of the arcuate section 23 is punctured by a plurality of perforations which may extend up the adjacent walls of the entry and exit chutes. A steam injection chamber is formed above the arcuate section by bridging the space between the entry and exit chutes with a channel-shaped insert 30. The insert 30 has side panels. 31 shaped to match the angle between the entry and exit chutes, and a top surface 32. An inspection hatch 33 is formed in the top surface.A steam inlet nipple 34 is welded into one sidewall 31 for external connection to a steam line and internal connection to a bellows-type steam injector 35. The unit 30 is then welded into the gap between the entry and exit chutes so as to form, in cooperation with the perforated arcuate wall 26, a steam injection chamber in communication with the interior of the soak tank.

When the perforations in the arcuate section 26 are formed by drilling, then care must be taken to remove all burrs to avoid snagging the towel. As an alternative to drilling directly into an existing soak tank, parts of the structure may be replaced by perforated panels. In another alternative, panels may be removed from the facing walls of the entry and exit chutes so that a complete or partly formed steam chamber can be inserted in the arcuate gap, i.e. the open areas of the channel-shaped insert 30 as illustrated are filled completely or partly with perforated panels.

The processing of towel B upstream and downstream of tank 21 is the same as the for towel A in tank 1.

In use of the modified soak tank, the soak liquid enters into the steam chamber through the perforated wall 26, where it is heated by injection of steam from the injector 35. The heated water can then recirculate back into the soak bath through the perforated wall 26. A temperature sensor is provided on the soak tank to control the input of steam.

Conveniently this may be provided on a plate closing the hatch 39, or adjacent thereto. The sensor is used to control input of steam to ensure that the temperature required by hygiene regulations is achieved. Typically the sensor is used to maintain a desired minimum and maximum temperature of the water in the soak tank.

The use of the steam injector 35 (with appropriate electrical controls) means that the temperature of the solution in the tank 21 can be controlled independently of the wash water and can so make up heat losses from the circulation system.

Therefore the temperature of the soak can be elevated to temperatures comparable to the wash temperature.

Additionally by increasing the width of the entry chute 22 (relative to Fig. 1) i.e. by moving wall 29 rearwards (the broken line indicates the corresponding position in the Fig.

1 tank) larger towel folds can be formed, thus increasing the residence time of the towel in the soak tank. Residence time may also be varied by adjusting the rates of feed/removal of the towel into the soak tank.

The steam injector 35 is isolated from the remainder of the tank 21 by the perforated wall 26. This prevents the towel from coming into contact with the injector and ensures that the heated solution is free to circulate into the other areas of the bath. Preferably a temperature dependent control device is provided to prevent the towel being withdrawn from the soak tank until an approved temperature has been reached.

The dimensions of a modified unit will clearly substantially reflect those of the existing unit. In general the present invention is aiming to provide means of increasing the soak temperature by about 10 C (typically to about 70 C) using steam injection, and to increase residence time by about 10 minutes (typically to about 68 minutes), by extending the longitudinal width of the entry chute or by other adjustments described above. Clearly the parameters of level of steam injection, volume of steam chamber, size and number of perforations and width of entry chute can be varied to suit the desired end point depending on the original conditions and dimensions.

When a soak tank is being built from new to incorporate the principles of this invention, it may simply be assembled with a linking section having its upper surface in place of top wall 32 to allow space for insertion of a steam injector and protective perforated screen or mesh, taking the place of the arcuate wall 26.

In an alternative embodiment, an external steam injection chamber in communication with the interior of the soak tank may be provided to heat the soak liquid, as shown in Fig. 4.

This embodiment makes use of a pre-existing inspection aperture to provide communication between the soak tank and an external steam injection chamber. Fig. 4 shows an existing J-tank provided with an inspection aperture 40, either at the base of the feed chute 42 or near the junction 43 of the exit chute 44 and the feed chute 42. Normally, removal of the inspection plate sealing the aperture 40 allows access to the inside of J-tank for cleaning purposes.

A box-like steam chamber 46 is constructed as shown in Fig.

5 to accommodate a bellows-type steam injector 45. The chamber is substantially L-shaped to form a toe portion of cross-section appropriate to link up with the existing inspection aperture. Preferably the end wall 47 of the toe portion is perforated and is secured to the J-tank to replace the inspection plate. When the J-tank is filled with water and detergent, the solution passes into the steam chamber 46 where it is heated by the steam injector 45. Heated water and steam passes back through the perforated plate 47 to heat the cleaning solution in the J-tank. The temperature is controlled in similar fashion to the previously described embodiment.

Although it is convenient to use an existing inspection aperture, clearly an external steam injection chamber could be attached to a J-tank at any point to communicate via appropriately formed apertures in the J-tank walls that will allow circulation of the soak water into and out of the chamber. The present invention has been described above in terms of both modifying an existing installed J-tank and of a modified J-tank that can be retro-fitted into an existing system.

Clearly, when installing a completely new system, the described method of heating the pre-wash soak is applicable to baths of different configuration.

Claims (9)

CLAIMS.

1. A method of cleaning a towel roll which comprises unrolling the towel and soaking it prior to washing, rinsing, drying and rewinding characterised in that during soaking of the towel in a bath of aqueous detergent, the bath is heated by injecting steam.

2. A method according to claim 1, in which the steam injector is placed in a separate chamber in communication with the liquid contents of the soak bath.

3. A method according to claim 1, in which the steam injector is positioned in the soak bath and separated from the towel path by a porous screen.

4. A soak bath unit comprising an entry chute, an exit chute and an intermediate linking section, and in which a chamber having a steam injector is provided in communication with the interior of the soak tank so that water in the soak tank can enter the chamber and receive steam injection.

5. A soak bath according to claim 4, in which perforations are provided in the upper wall of the section linking the entry and exit chutes, and additional upper and sidewalls are provided to close the space between the entry and exit chutes, so as to form, with the perforated wall, a steam injection chamber communicating via the perforations with the linking section.

6. A soak bath according to claim 4, in which the steam injection chamber is an external chamber having access to the interior of the soak tank through an aperture or apertures in the wall of the soak tank.

7. A soak bath according to claim 4, in which the steam injection chamber is formed in the interior of the soak tank and comprises a steam injector and a porous screen separating the region surrounding the steam injector from the region through which in use the towel must pass.

8. A soak tank according to any one of claims 4 to 7, including a temperature sensor to control injection of steam.

9. A soak tank according to claim 4, substantially as described herein with reference to Figs. 2 and 3 or Figs. 4 and 5 of the accompanying drawings.