Open-width washing

Abstract

 OPEN WIDTH WASHING
A fabric 510 to be scoured is sprayed by a succession of spray pipes 520 with a liquid which is liable to froth or foam. Two suction slots 512 and 514 are arranged to draw liquid through the fabric from a pool 518 of liquid resting on top of the fabric. The liquid removed from the suction slots 512 and 514 can be recycled. The liquid which is removed from an upper suction slot 516, together with any air which may be entrained therein, is passed to a separator unit in which the majority of the liquid is supported from beneath throughout the unit, at least until the gas has been separated from the liquid, in order to avoid undue frothing or foaming of the liquid.

Description

[0001] The present invention relates to a method of, and apparatus for the washing of open width fabric, and in particular, although not exclusively, to the scouring of lightweight, plain woven fabrics such as wool/mohair fabrics. In this specification the term "washing" includes scouring and rinsing.

[0002] The present invention also relates to a method of drawing off liquid liable to froth or foam and separating it from gas and to a separator of gas from such liquid.

[0003] When scouring lightweight plain woven fabrics it is desirable that the cloth be in open width rather than being "roped", as the fabric is susceptible to creasing. In a known arrangement for washing a continuous length of fabric in open width (as opposed to a loop of such fabric) machines are arranged in series through which the fabric is passed successively. In each machine the fabric is caused to dwell in a tank of liquid in order to saturate the fabric whilst being mechanically agitated by various methods before being taken upwardly and being passed through a pair of opposed expression rollers which exert a high pressure on the fabric in order to squeeze the liquid out of the cloth and thus scour the cloth.

[0004] In scouring, an expensive liquor is added to water in order to assist in the scouring operation. As it is necessary to provide a large tank for the fabric to dwell, and be agitated in before being passed through the expression rollers, a large volume of liquid is required in the tank and accordingly, in order to be cost effective, only a relatively small amount of liquor is added to the water. This causes the liquid to be a very diluted solution and only a marginal benefit is achieved by the action of the diluted liquor on the fabric.

[0005] The expression rollers and particularly the agitation systems are extremely complicated and expensive to produce and operate and the rollers may have to exert a pressure on the fabric of several tons per square inch in order to remove liquid from the fabric. Furthermore, as the rollers exert such a great pressure, should the fabric get a crease it it which is passed through the rollers that crease can be put into the fabric permanently thus ruining the fabric.

[0006] As each machine including a pair of expression rollers and agitation system is expensive in itself, the provision of such machines in series makes scouring by this method a very expensive operation.

[0007] According to one aspect of the present invention, a method of washing open width fabric comprises creating a pressure differential across the fabric to get liquid out of the fabric. The pressure differential may be created by forcing a gas, which may comprise air, through the fabric. The pressure differential may be caused by sucking or blowing. such a method may have a particularly advantageous washing effect on the fabric as the liquid is pulled or driven out of the fabric rather than in the prior expression rollers where some of the liquid is squeezed out and some of the liquid is squeezed into the fabric. The liquid may be liable to froth or foam. Previously the getting of such liquid out of a fabric has not been proposed as such an extraction method would lead to a rapid accumulation of froth or foam which would stop the machine from functioning. Accordingly the only liquids which have previously been removed from fabric are those which are not liable to froth or foam such as the moisture control system shown in UK Patent Publication No. 2 114 917A in which moisture is removed by a vacuum.

[0008] The method may comprise first sucking liquid out of the fabric, then wetting the fabric before again sucking liquid out of the fabric. The liquid wetting the fabric may contain liquor, and the concentration of liquor in the liquid may be reduced between two or more successive wettings of the fabric.

[0009] The method may comprise sucking a substantial amount of liquid out of the fabric, and may comprise sucking approximately half or even 5/6ths of the liquid out of the fabric. The fabric may have a weight of liquid approximately three times the weight of the fabric prior to sucking the liquid out of the fabric.

[0010] The method may further comprise recycling liquid which has been sucked out of the fabric to wet the fabric.

[0011] The method of wetting the fabric may include spraying the fabric with liquid prior to sucking the liquid out of the fabric, which spraying may be done by jets.

[0012] The method may include causing relative movement of the fabric through a restricted gap to cause liquid to penetrate voids in the fabric prior to sucking the liquid out of the fabric. The restricted gap may be provided by rollers at least one of which may be driven in order to transport the fabric. Any pressure exerted on the fabric may be small and may be of the order of tens of pounds per square inch. The method may comprise exerting a lifting force on an upper roller whereby the whole of the weight of that roller is not exerted on fabric between the rollers.

[0013] The method may include repeatedly sucking liquid out of a particular length of fabric with a common sucking means.

[0014] The method may comprise sucking liquid out of a loop of fabric or, alternatively, the method may comprise sucking liquid out of a length of fabric.

[0015] The method may comprise sucking liquid out of a fabric through a slot extending across the fabric. Alternatively the method may comprise sucking liquid out of the fabric through openings, which openings may be staggered from each other in the direction extending across the fabric. The complete extent of the fabric may pass over the openings, or only portions of the fabric may pass thereover.

[0016] The method of washing may comprise a method of scouring.

[0017] The liquid which is sucked out of the fabric may be an aqueous liquid.

[0018] According to another aspect of the present invention a method of drawing off liquid liable to froth or foam and separating it from gas comprises causing the majority of the liquid to flow over a supporting surface which always supports the liquid and causes the liquid to flow along prior to removing the liquid from a lower region and removing the gas from an upper region. With such a method, as the supporting surface always supports the majority of the liquid and causes that liquid to flow along, the liquid is not able to fall unsupported and then froth or foam when its fall is broken.

[0019] The method may comprise supplying the gas and liquid through an inlet to a chamber and may comprise removing the gas from a higher region that the inlet. The method may comprise supplying the liquid to an expansion chamber and causing the velocity of the gas to be reduced from the velocity of the gas prior to entering the chamber. The method may comprise supplying a plurality of inlets each having gas and liquid to a chamber and taking off liquid from two or more outlets, which may enable the liquid from each inlet to be kept separate whilst using a common gas or suction source. The method may also comprise passing gas over the liquid prior to the liquid reaching the chamber.

[0020] The method may further comprise recycling either the separated gas or liquid or both.

[0021] According to another aspect of the prsent invention, apparatus for washing open width fabric includes pressure differential inducing means arranged to create a pressure differential across the fabric to get liquid out of fabric. The pressure differential inducing means may comprise means for forcing a gas, which may comprise air, through the fabric. The pressure differential inducing means may comprise sucking or blowing means. The apparatus may include a plurality of sucking or blowing means. The apparatus may include wetting means arranged to wet the fabric with liquid, and the wetting means may include liquid spraying means.

[0022] The apparatus may include a restricted gap through which fabric is arranged to pass. The restricted gap may be provided by a pair of opposed rollers. At least one of the rollers may be a driven roller. The pressure exerted by the rollers on fabric located therebetween may be arranged to be small and may be of the order of tens of pounds per square inch. One of the rollers may be located above the other roller, and the weight of the upper roller acting on the lower roller may be reduced by lifting means acting to exert an upwards force on the upper roller.

[0023] Recycling means may be provided arranged to recycle liquid which has been sucked out of the fabric by the sucking means and return that liquid to wet the fabric.

[0024] The apparatus may include collecting means arranged to collect liquid falling off fabric and may also include return means arranged to return the liquid to the fabric.

[0025] The apparatus may include a scouring stage in which an aqueous solution containing a liquor is arranged to be supplied to the fabric and then sucked out of the fabric by sucking means, and a washing stage in which water is arranged to be supplied to the fabric prior to further sucking means sucking the liquid out of the fabric.

[0026] The sucking means may comprise a slot arranged in use, to extend across the fabric. Alternatively the sucking means may comprise a plurality of openings, which may be staggered from each other, arranged, in use, to extend across the fabric. The openings may be arranged such that only a portion of the fabric passing over the suction means passes over the openings.

[0027] The present invention also includes a fabric which has been washed by the method or apparatus according to the invention.

[0028] According to another aspect of the present invention, a method of washing open width fabric comprises creating a pressure differential across the fabric to get liquid only out of the fabric.

[0029] According to a further aspect of the present invention, a method of drawing off liquid liable to froth or foam and separating it from gas comprises causing the majority of the liquid to flow over a supporting surface which always supports the liquid and causes the liquid to flow along prior to removing the liquid from a lower region and removing the gas from an upper region. The present invention includes a separator arranged to separate gas from liquid by a method as herein defined.

[0030] According to a further aspect of the present invention, a separator of gas from liquid liable to froth or foam comprises a supporting surface always having a horizontal component of direction along its length, and a gas outlet located at a higher level than a liquid outlet.

[0031] The separator may include a chamber housing an inlet for the gas and liquid, and an air outlet may be provided at a higher level than the inlet. The chamber may comprise an expansion chamber.

[0032] Recycling means may be provided arranged to recycle either the separated gas or liquid or both.

[0033] The present invention includes a method of separating gas from liquid using a separator as herein defined.

[0034] The present invention includes any combination of the herein described features.

[0035] The invention may be carried into practice in various ways, but several embodiments will now be described by way of example and with reference to the accompanying drawings, in which:-

Figure 1 is a schematic side view of a scouring apparatus;

Figure 2 is a side view of a separator used in recovering liquid removed from the fabric through the suction slots of the apparatus shown in Figure 1;

Figure 3 is a plan view of Figure 2, and

Figure 4 is a side view taken along the line IV-­IV of Figure 2, and

Figure 5 is a schematic diagram of a further embodiment of the present invention.

[0036] In the embodiment illustrated in Figure 1, for scouring and washing a continuous length of open width, lightweight, plain weave wool/mohair fabric 10, the fabric passes successively through three stages 100, 200 and 300, and as each of those stages are similar in construction, only stage 100 has been shown in detail.

[0037] The previously wet out or impregnated fabric 10 enters the stage 100 and passes over a roller 102 and then extends downwardly under a roller 104 before passing upwardly and between a pair of transport rollers 108. The fabric then extends horizontally over a suction slot 114 and then upwardly partly around each of a further pair of transport rollers 116 before extending downwardly around a roller 118 and then upwardly and between a pair of transport rollers 120. The fabric then passes over a further suction slot 122 and then upwardly and partly around each of a pair of transport rollers 124 before passing downwardly around the roller 202 at the beginning of the stage 200.

[0038] In use, the fabric is impregnated or soaked by liquid supplied by four spray pipes 126 or jets which spray the back and face of the fabric as it passes downwardly towards the roller 104 and upwardly from that roller. In this way the fabric becomes saturated and excess liquid from the spraying flows down each face of the fabric to further enhance the wetting of the fabric.

[0039] The fabric then passes through the transport rollers 108 which exert a small nip pressure of the order of tens of pounds per square inch. The lower roller is driven to pull the fabric through the previous section of the apparatus, and the small nip pressure serves to force the liquid into the voids in the fabric rather than squeeze the water out of the fabric. In order to reduce the pressure exerted on the fabric by the rollers 108 a pair of lifting devices 128 may act (possibly depending upon the fabric) on either end of the upper roller to support a proportion of the weight of that upper roller.

[0040] As the rollers 108 only exert a small nip pressure on the fabric, should a crease occur in the fabric this need not be a permanent crease and can be ironed out at a later stage in the processing of the fabric.

[0041] In an alternative embodiment (not shown) the low pressure rollers are omitted and are replaed by a curved expansion roll which is not driven. The curved expansion roll includes a flexible covering and serves to stretch the fabric, or keep the creases out of the fabric as the fabric passes over the roll. The curved expansion roll is free to rotate and causes the fabric to spread as it passes around the roll. In the embodiment shown in Figure 1, the modification is to replace the rollers 108 and 120 by curved expansion rolls and to replace the roller 116 by a straight idler roll.

[0042] When the fabric leaves the rollers 108 it contains approximately its own weight of liquid (in the embodiment without the rollers 108 it contains approximately three times its own weight). The fabric then passes over the suction slot 114 which exerts a downwards pulling force on the fabric and sucks most of the liquid out of the fabric until about half the weight of liquid to the weight of fabric remains. The suction action provides an extremely efficient method of scouring the fabric as the liquid is actually pulled through or out of the voids in the fabric thus ensuring passage of concentrated scouring liquor through the fabric rather than as in the prior devices in which diluted liquor may remain in the fabric without necessarily passing through the fabric. The fabric is then pulled by the transport rollers 116, the upper roller of which may be provided with the lifting devices 128.

[0043] As the fabric travels downwardly from the transport rollers 116 and then upwardly from the roller 118 it is again sprayed on the back and face in each direction of travel by four spray pipes 130 before passing through the transport rollers 120, over the suction slot 122 and then upwardly around the transport rollers 124. The transport rollers 120 exert a small nip pressure on the fabric which serves to force the liquid into the voids in the fabric rather than squeezing the water out of the fabric, and the fabric approaching the suction slot may contain its own weight in liquid, with the suction slot 122 removing liquid such that only half the weight of liquid to fabric remains. The upper transport rollers 120 and 124 are provided with lifting devices 128.

[0044] Any liquid which falls off the fabric during its progress through the stage 100 is returned to the collection tray 106 by running down the inclined base 132. Liquid sucked out of the fabric by the slots 114 and 122 is returned to the tray 106 via lines 134. Liquid is taken from the collection tray and supplied to the spray pipes 126 and 130 via lines 136. Thus liquid in the stage is recycled and it is only necessary to have a relatively small volume of liquid in the stage, for instance 50 gallons (as compared to 250 gallons in a comparable prior machine). This is particularly advantageous in the early scouring stages as the liquid contains an extremely expensive liquor which enhances the scouring effect, and the concentration of the liquor is able to be greatly increased over existing scouring machines in which a large reservoir of liquid is provided for the cloth to soak and be agitated in before being squeezed.

[0045] In the first stage 100 extremely concentrated liquor is used as the liquid for spraying the fabric. In the second stage 200 warm water is introduced into the liquid to start to clean up the fabric. In the third stage 300 just warm water is used as the liquid to rinse the fabric. Thereafter the fabric may be cooled with cold water

[0046] In the rinsing stages the liquid need not be recycled (and indeed this recycling is optional in the other stages).

[0047] As the liquid in the fabric is pulled through by the suction the scouring effect and rinsing of the fabric is extremely effective, particularly when compared to the prior devices in which the same liquid will tend to remain in the voids in the fabric with only the excess liquid being removed by the expression rollers.

[0048] In an alternative embodiment (not shown), the suction slots are replaced by suction pipes over which the cloth passes, the pipes having a plurality of openings comprising holes over which the cloth passes. These openings may be offset from each other along the pipe in order that each part of the cloth passes over at least a portion of an opening. Alternatively the openings or holes may be spaced from each other in the direction of the longitudinal axis of the pipe with some strips of the fabric not actually passing over an opening: with this arrangement it is thought that those strips not passing over an opening will still be scoured as the liquid is drawn into the openings under suction from portions of the fabric over the opening and portions of fabric adjacent to the openings. For example, in one embodiment, a single row of openings or holes one eighth of an inch diameter may be provided on one quarter inch centres along the pipe. With these modified arrangements the scouring effect remains the same (or may even be slightly better) as that provided by the suction slot, but less drag is placed on the fabric.

[0049] Once the fabric has left the final rinsing stage it is dried in a conventional manner.

[0050] Although the specific embodiment has been described in relation to the scouring and rinsing of a continuous length of fabric it will be appreciated that it could be readily adapted to the corresponding treatment of a length of fabric whose ends are connected to form a loop with the loop passing over one or more suction slots.

[0051] In a further embodiment (not shown) the pressure differential across the fabric, instead of being created by suction, is created by blowing air through the fabric.

[0052] In addition, in the case of both the loop and continuous arrangements the fabric leaves the machine with a moisture content which renders further mechanical water removal prior to drying unnecessary.

[0053] In a further embodiment (shown in Figure 5), the fabric 510 is arranged to pass over a succession of three suction slots or openings 512, 514 and 516 located one above the other. In that embodiment the fabric is pulled in a generally upwards direction and any liquor which falls off the higher portions of the fabric may fall back and serve to further wet the fabric below.

[0054] In Figure 5 where the slots are located one above the other, or in any embodiment, the fabric may be arranged to extend across the or each slot in a generally horizontal direction. The fabric approaching or over the slots downstream of the last slot may have a layer or pool of liquor 518 over the fabric imparted by spray pipes 510 in which case the slots may pull only liquor from the fabric, without any air thus ensuring the maximum effect of the liquor on the fabric. The fact that only liquor is pulled through allows a significantly greater amount of liquor to pass through the fabric than if air were also present. This feature is particularly advantageous where the liquor tends to froth or foam when mixed with air as no air is drawn into the slot and consequently no, or little frothing or foaming will occur. As liquid only is drawn through the fabric the cooling effect of the air being drawn through the fabric is not present and thus less heat is required to maintain the fabric at the desired temperature. Furthermore, a smaller pump may be able to be used than where air is also being drawn through the fabric. Liquor from the pool 518 above the slot 514 may flow over and fall into the pool 518 beneath.

[0055] In the embodiments, spray pipes 126, 130 and 520 have been described. In an alternative embodiment (not shown) angled spray jets are provided instead of the spray pipes, or incorporated into the spray pipes, in order to obtain a more even coverage.

[0056] As the liquor which is drawn off the fabric contains dilute soap, the liquid tends to froth it is is unduly agitated, particularly where it contains air, and once significant frothing has occurred, it then takes a considerable amount of time to settle again, and thus the liquor may not be recycled again through the spray pipes or jets until an undue delay has occurred and the entrained air has largely left the liquid.

[0057] In Figures 2, 3 and 4, there is shown a separator 400 for separating the liquid from the air which is drawn through the suction means from the fabric.

[0058] Three tubes 402, 406 and 408 are shown leading from different suction slots or pipes into an expansion chamber 410. The cross-sectional area of each tube is more than and may be approximately twice that of the slots or openings from the suction device from which they lead (c.f. 7 square inches to 3.5 square inches), and accordingly the liquid flows along a lower region of each tube with air being drawn over the top of the liquid in that stage by a vacuum air pump leading to a higher region of the expansion chamber than the tubes by a pipe 412. It is thought that the frothing of the liquid is kept down in the tubes by the speed of the air flowing over the liquid. When the liquid reaches the expansion chamber the majority flows gently towards an outlet pipe 414 (for the tube 402), and a common outlet pipe 416 (for the tubes 406 and 408). In the expansion chamber, a partition 418 is provided to divide the flow of the majority of the liquid from the tube 402 from the tubes 406 and 408.

[0059] It will be appreciated that more or less tubes could be provided leading to the expansion chamber and portions can be added, as desired, or even omitted.

[0060] As the air enters the expansion chamber from the tubes 402, 404 and 406, some of that air will contain small droplets of liquid, and these decelerate and fall as the air travels across the expansion chamber, and as the velocity of the air falls, either to rejoin directly the liquid flowing along the lower surface of the expansion chamber or to impinge on the end wall 420 of the expansion chamber and flow down to the liquid at the bottom of the chamber.

[0061] Where the pipes 402 and 406 are drawing liquor only there will be no separation of air from the liquor in the separator, and in that case the pipes 402 and 406 could be arranged such that they recycle the liquor therein without the liquor having to go through the separator.

[0062] The outlet pipes 416 and 418 are connected to separate rotating screw pumps which draw the liquid out of the expansion chamber. These pumps can be set such that they are always scavenging from the expansion chamber so that the liquid or any froth which may be present can not build up and leave the chamber through the pipe 412 to the air vacuum pump. The liquid leaving the mono pumps can be fed straight back to the spray pipes or jets, if desired.

[0063] As the air which is drawn off by the air vacuum pump is always "dry", the pump can be relatively cheap (as compared to a liquid ring type) both to buy and to run. Furthermore, the pump imparts some heat into the already warm air which is drawn through the expansion chamber, and the outlet of warm air from the pump can be returned over the top of the suction slot to assist in the liquid being removed from the cloth, with the heat from the air serving to increase evaporation, heat the fabric and lower the viscosity of the liquor. Thus the cloth receives some heat at the suction slot and it is not necessary to heat the cloth prior to it reaching the slot to the same degree as if no heat were added at the suction slot, and consequently there is a considerable energy saving.

Claims

1. A method of washing open width fabric (10,510) with a liquid liable to froth or foam comprising creating a pressure differential (114,122,512,514,516) across the fabric (10,510) to get the liquid which is liable to froth or foam out of the fabric.

2. A method as claimed in Claim 1 in which liquid only is got out of the fabric as a result of the pressure differential (512,514).

3. A method as claimed in Claim 1 or 2 in which the fabric includes a pool (518) of liquid on the upwardly facing surface thereof whilst the pressure differential (512,514) is getting liquid out of the fabric from the downwardly facing surface of the fabric beneath the pool (518).

4. A method as claimed in any preceding claim in which the liquid which has been got out of the fabric is separated from any gas with which it may be associated by causing the majority of the liquid to flow over a supporting surface which always supports that majority of the liquid and causes that liquid to flow along prior to removing the liquid from a lower region (414,416) and removing any gas from an upper region (412).

5. A method as claimed in Claim 4 in which the liquid and any gas are caused to pass through an inlet (402,406,408) into a chamber (410), and any gas is removed from the chamber from a higher region (412) than the inlet (402,406,408) to the chamber.

6. Apparatus for washing open width fabric with a liquid liable to froth or foam comprising pressure differential inducing means (114,122,512,514,516) arranged to create a pressure differential across a fabric (10,510) to get liquid liable to froth or foam out of the fabric (10,510).

7. Apparatus as claimed in Claim 6 including liquid supply means (520) arranged to supply sufficient liquid onto the upwardly facing surface of a fabric to enable there to be a pool (518) of liquid on a fabric whilst the pressure inducing means (512,514) is arranged to get liquid out of a fabric (510) from below, beneath the pool (518).

8. Apparatus as claimed in Claim 6 or 7 including a separator (400) arranged to separate any gas from liquid which has been got out of fabric, the separator (400) including a supporting surface always having a horizontal component of direction along its length.

9. Apparatus as claimed in Claim 8 in which the separator (400) includes a gas outlet (412) located at a higher region than an inlet (402,406,408) for the liquid and any gas to the separator (400).

10. Apparatus as claimed in Claim 8 or 9 in which the separator (400) is arranged to receive liquid and any gas from a plurality of locations.

Drawing