WO2019016525A1

WO2019016525A1 - Improved drying methods

Info

Publication number: WO2019016525A1
Application number: PCT/GB2018/052005
Authority: WO
Inventors: George A. SILVIA JR.; David John XAVIER; Steven Kenneth CHASE
Original assignee: Xeros Limited
Priority date: 2017-07-18
Filing date: 2018-07-13
Publication date: 2019-01-24
Also published as: GB201711542D0; GB2564669A

Abstract

There is provided a method for drying a substance and associated apparatus. The method involves drying a substance within a cylindrical drum having an open front end and a closed rear end separated from the front end along an axis by a cylindrical wall having at least one aperture passing through the circumferential wall. The method includes the steps of rotating the drum about the axis and drawing air through the cylindrical drum along a flow path which enters the cylindrical drum through the open front end and/or the closed rear end and exits the cylindrical drum through the at least one aperture passing through the circumferential wall.

Description

IMPROVED DRYING METHODS

The present disclosure relates to an apparatus and method that improves the drying of substances, particularly substrates and more particularly a substrate which is or comprises a textile, by optimising airflow through a cylindrical drum. The present disclosure further relates to a method and apparatus for cleaning and drying substances by improving the sequencing of washing and drying cycles to which an apparatus operates.

Tumble drying processes are a mainstay of both domestic and industrial textile fabric cleaning procedures and typically involve placing the textiles in a container such as a perforated cylindrical drum which is rotated in alternating clockwise and anticlockwise cycles whilst hot air is introduced into the drum through the apertures. A combination of the hot air treatment and the mechanical action of the tumbling process causes water to be expelled from the textile materials in order that drying is achieved.

However, such processes, though generally very effective, are usually characterised by high levels of energy consumption, both in terms of effecting rotation of the container and, most particularly, in generating and circulating heated air. Typically, prior art processes may involve prolonged treatments at high temperatures in order to effect the required degree of drying. Clearly, however, the lower are the energy requirements of a system, the more efficient is the system and its associated drying process. Consequently, there is a desire to reduce both the time of such drying treatments, the temperature and air flow rate at which they are carried out in order to provide more efficient processes, whilst maintaining equivalent drying performance.

Recent advances in technology have improved the performance and energy efficiency of some dryers. For instance, WO2012/098408 A2 discloses an improved drying method comprising treating a wet substrate with a solid particulate material. However, further improvements are still possible. Energy consumption in industrial tumble drying is usually higher than domestic application, partly due to the desire for faster cycle times. It is also noteworthy that, overall, tumble drying is significantly less efficient than washing as a component part of the laundry process in either sector.

Heating of the circulating air is the principal use of energy in such tumble dryers, whilst rotating the drum and circulating the air flow are also significant factors. The longer it takes for substances within the drum to reach the required degree of drying, the longer the air must be heated and circulated, and the longer the drum must be rotated. Moreover, with consumers demanding ever faster cycle times, there is a pressure on manufacturers to resort to higher temperatures and/or faster air flow rates in order to dry substances more quickly. Of course, this leads to higher energy requirements, which is not satisfactory. The present inventors have therefore sought to effect improvements in the prior art processes by improving the efficiency with which drying is achieved for a given temperature and/or air flow rate, and to seek other ways to reduce the time taken to reach the required degree of drying.

Mechanical action in a conventional, horizontal axis tumble dryer is generated by the forces acting on the fabric through falling and hitting either other fabric or the dryer inner drum surface, whilst the fabric is interacting with the forced hot air flow. This results in release and evaporation of water from within the fabric, and hence drying. However, once water from within the fabric has been released and evaporated it remains necessary to remove the moist air from within the drum. The present inventors have realised that a limitation on the speed and efficiency of the drying process is the ability to replenish moist or saturated air within the drum with dry air. Improvements to this aspect of the drying process have therefore been sought out.

One way to pass air through a rotating drum would be to introduce it through one of the front and the rear of the drum, and cause it to exit through the other. This way, the air would pass through the drum approximately parallel to the axis about which the drum is rotating. Although such a configuration is believed to be advantageous in terms of its drying efficiency, the inventors have found significant challenges in configuring access to the drum to facilitate an air flow through both the front and the rear. In particular, space at the rear of the drum is typically taken up with a drive mechanism for rotating the drum, and there are also difficulties in passing an air flow through a closed rear end. The present inventors also speculate that passing air only axially through the drum may not be optimal in some situations because air may tend not to circulate within the drum, and in particular may not circulate around substrates that are forced against the inner surface of the drum by centrifugal force. Instead, in such a configuration, air would tend to travel along a flow path approximately parallel to the axis through the middle of a ring of circulating substrates. This is not an effective configuration for optimising drying.

Another flow path arrangement has been developed in the Electrolux® Pronto® combination washer-dryer, which introduces air into the drum radially rather than axially. Figures 1 and 2 show diagrams of an Electrolux® Pronto® combination washer-dryer 1. In figure 1 , arrows 10 indicate the direction of a flow path of air that is drawn through the drum 12 of the washer- dryer 1 by fan assembly 14. As shown, air passes through an inlet 16 in the rear of the washer-dryer 1 through a burner 18. The flow path then passes through an aperture 20 in a sidewall of a cage in which the drum 12 is rotatably mounted. The air flow can be seen travelling toward the drum's axis of rotation, passing through apertures in the cylindrical wall of the drum 12. The air flow may circulate within the drum 12 and/or cage, before passing out of the front of the drum, after which is it drawn (again, by fan assembly 14) through ducting passing across the base of the washer-dryer 1. After passing through the fan assembly 14, the air flow exist the washer-dryer 1 through an exhaust 22. Figure 2 shows the Electrolux® Pronto® combination washer-dryer 1 of figure 1 , wherein air is draw from the front of the drum, around the outside of the cage 24 and joins the aforementioned flow path prior to burner 18, after which it follows the same flow path described above. The present inventors have found that whilst the airflow in the Electrolux® Pronto® is improved over the arrangement through which air enters and exits in the axial direction, the configuration remains unsatisfactory. In particular, because substrates are forced against the inner surface of the drum by centrifugal force, apertures in the cylindrical wall of the drum become blocked, preventing air from passing through the apertures into the drum. A consequence of blocking air from entering the drum though apertures in the cylindrical wall of the drum is that the air passes around the outside of the drum in a process known colloquially as 'skirting'. Not only is skirting indicative of air not entering the drum to cause the desired level of drying, it may also cause warm air to infiltrate components of the device not intended to be exposed to such conditions. This is particularly problematic for components which are sensitive to heat.

A particular problem is experienced when a dry cycle is applied to washer configurations that utilise a collection chamber or 'sump' beneath the drum to collect water and/or solid particulate material extracted from the drum. Such configurations are known from, for example, WO2011/098815A1 and WO2014/147390A1 , among others. Typically, there exists an opening between the collection chamber and drum such that the contents of the sump (e.g. water and/or solid particulate material) is not isolated from the drum. Here, where a washer-dryer experiences 'skirting', a flow of air that is intended to pass through the drum to facilitate drying of substrates therein may instead pass in close proximity to the collection chamber such that water within the collection chamber evaporates and consequently the capacity of the resulting moist flow of air to take up water from within the drum is reduced. In other words, without the collection chamber being isolated from the drum, the efficiency of the washer-dryer is reduced because air flow is used to evaporate the contents of the collection chamber and not the water in the substrates in the drum. A solution to this problem is to isolate the collection chamber from the drum before introducing an air flow to facilitate the dry cycle.

In a related problem in combination washer-dryers, particularly those used in industry, the time taken to complete a full wash cycle followed by a full dry cycle is long. The desire to minimise the time taken to complete the cycles leads to washer-dryers using higher temperatures and/or faster air flow rates than would be preferred in order to dry substances more quickly.

The present inventors have sought to devise a new approach to the drying problems, which allows the above deficiencies associated with the methods of the prior art to be overcome. Accordingly, the present invention provides an apparatus suitable for drying a substance, said apparatus comprising a housing having mounted therein:

(i) a cylindrical drum having an open front end and a closed rear end separated from the front end along an axis by a circumferential wall having at least one aperture passing through the circumferential wall or a component mounted thereon, the cylindrical drum being rotatably mounted along the axis about which it is configured to rotate; and

(ii) a fan assembly configured to draw air along a flow path passing through the cylindrical drum;

wherein the flow path enters the cylindrical drum through the open front end and/or the closed rear end and exits the cylindrical drum through the at least one aperture.

It was found that entry of a flow of warm air through the open front end or closed rear end (i.e. the ends that are spaced apart along the axis of rotation of the drum) has a number of advantages and leads to a more efficient drying cycle which takes less time than known equivalents.

In a preferred apparatus, a plate is coaxially aligned with the cylindrical drum. The plate has at least one opening, and the flow path enters the cylindrical drum by passing through the at least one opening in the plate. The plate may form part of the body or housing of the apparatus, and may serve functions in addition to that specified herein. Alternatively, the plate may be provided specifically for achieving the present invention. A plate could be retrofit onto existing devices to provide them with the present invention. Preferably the plate is mounted on the housing such that the at least one opening in the plate is positioned, in a radial direction extending from the axis, between the axis and the inner periphery of the cylindrical drum. This can be measured by identifying where at least a portion of the at least one opening in the plate is situated in a radial direction extending from the axis. Preferably that portion is some way from the edge of the inner periphery of the drum, and some way from the central axis. Preferably it is between 5% and 95% of the distance between the axis and the inner periphery of the cylindrical drum, preferably between 25% and 75%, more preferably between 30% and 60%.

The position of the said at least a portion of the at least one opening in the plate can also be measured by where it is located in the plate in a circumferential direction about the axis. This is conveniently measured by reference to a clock face (i.e. with the 12 o'clock position being vertically upwards and the 6 o'clock position being vertically downwards) or using degrees wherein 0° is vertically upwards. Preferably the at least a portion of the at least one opening is between 180° and 360° in a clockwise direction from vertically upwards, preferably between 270° and 360°, more preferably between 300° and 330°.

Preferably a ducting portion is mounted to the plate coupled to an air intake such that the flow path passes from the air intake through the ducting portion to the at least one opening in the plate. The purpose of the ducting portion, is to guide the warm air into the drum from the air intake.

Preferably the apparatus comprises a source of heat at the air intake configured to supply a flow of heated air drawn along the flow path through the air intake. The source of heat may be one or more of a combustion chamber, an electrical heater and a source of steam. Other heaters are also possible.

The housing of the apparatus will preferably comprise a door coaxially aligned with the cylindrical drum. The plate and the ducting portion will not overlap the door, and will therefore at least partially surround the door. In some embodiments, the plate and the ducting portion may fully surround the door leaving an opening through which substrates are passed into the drum. The source of heat is conveniently mounted to a roof of the housing, in which case it is preferably for the plate and the ducting portion to at least partially surround an upper portion of the door so that the pathway from the heater to the drum is as short as possible. Were the source of heat mounted elsewhere (to a side or the bottom of the housing, for instance), it may be that the plate and the ducting portion would at least partially surround the portion of the door closest to that source of heat. Preferably the innermost periphery of the plate and the innermost periphery of the ducting portion, in a radial direction extending toward the axis, conform to the shape of an outermost periphery of the door, in a corresponding direction. For instance, the innermost peripheries of the plate and the ducting portion and the outermost periphery of the door may be at least partially arcuate or annular, both of which configurations are suitable when the door is circular.

As with some conventional apparatuses, the housing has mounted therein a tub within which the cylindrical drum is rotatably mounted. According to a preferred embodiment of the invention, the tub comprising an exhaust opening through which air is drawn by the fan assembly after passing through the cylindrical drum. To catch lint and other debris (as well as solid particulate material if that is used in the process, the apparatus may further comprise a filter mounted across the exhaust opening.

In some embodiments the housing further comprises a front wall and a rear wall separated from the front wall along the first axis by one or more sidewalls and a roof. The fan assembly may be mounted to either the inner or outer skin of one of the front wall, rear wall, a sidewall or the roof. Alternatively, the fan assembly may not be mounted to these walls and could be mounted to a chassis or other part of the apparatus. The flow path will exit the housing through said front wall, rear wall, sidewall or roof, either through the fan assembly itself or through an opening in ducting leading to or from the fan assembly.

One or both of the exhaust opening and the fan assembly may occupy a position situated, in a circumferential direction about the axis, between 0° and 180° in a clockwise direction from vertically upwards, preferably between 30° and 150°, more preferably between 60° and 120°, most preferably 90°. Alternatively, at least a portion of the exhaust opening may occupy a position situated, in a circumferential direction about the axis, between 90° and 270° away from at least a portion of the at least one opening in the plate, preferably between 120° and 240°, more preferably between 150° and 210°, most preferably 180°. In some embodiments of the invention, the apparatus of any preceding claim may further comprise a collection chamber mounted beneath the cylindrical drum for the collection and storage of water and/or solid particulate material that drains or else is transferred from the cylindrical drum.

There may be a valve, preferably a butterfly valve, situated between the collection chamber and the cylindrical drum (typically sealing the collection chamber from the tub) to selectively allow or prevent drainage and/or transfer of water and/or solid particulate material from the drum to the collection chamber. There is preferably a control system configured cause the value to move between open and closed positions. The control system that operates the valve may also actuate the fan assembly to cause air to be drawn along the flow path, as described above. In this case, the control system may be configured to actuate the fan assembly to cause air to be drawn along the flow path whilst the valve is in its open position, without the loss of efficiency of the drying process that might be expected.

The present invention also provides a method of drying a substance within a cylindrical drum having an open front end and a closed rear end separated from the front end along an axis by a cylindrical wall having at least one aperture passing through the circumferential wall, the method comprising rotating the drum about the axis; and drawing air through the cylindrical drum along a flow path which enters the cylindrical drum through the open front end and/or the closed rear end and exits the cylindrical drum through the at least one aperture passing through the circumferential wall.

Optional steps of the method correspond to preferred features of the apparatus mentioned above.

In a second aspect, the invention provides a method of operating an apparatus for use in washing and drying a substance, the method comprising:

introducing wash water into a drum comprising a substance;

operating the apparatus in a wash cycle, including a step of operating the apparatus in an extraction phase of the wash cycle, the extraction phase comprising at least:

rotating the drum at a first speed and thereby extracting wash water from the drum; operating the apparatus in a dry cycle, including a step of operating the apparatus in an air-drying phase of the dry cycle, the air-drying phase comprising at least:

rotating the drum comprising a substance at a second speed that is slower than the first speed whilst maintaining a flow of air into the drum to provide an environment within the drum at a drying temperature; the method further comprising: transitioning the apparatus from operating in the wash cycle to operating the apparatus in the dry cycle, the step of transitioning comprising introducing a flow of air into the drum to raise the temperature of the environment within the drum from a first temperature toward the drying temperature, wherein the step of introducing the flow of air begins prior to completion of the extraction phase of the wash cycle.

Because the operation method does not wait for completion of the extraction phase of the wash cycle before introducing air into the drum to heat a substance therein, the whole process takes less time.

According to the invention, the step of introducing a flow of air into the drum may begin at any time before completion of the extraction phase of the wash cycle, but preferably it begins at the beginning of the extraction phase. Applying heat to the flow of air may raise its the temperature to any suitable temperature, but this is usually at least 80°C, preferably at least 100°C, preferably at least 120°C, preferably at least 140°C. The drying temperature may be between 40°C and 140°C, preferably between 50°C and 120°C, more preferably between 60°C and 100°C, most preferably between 70°C and 80°C.

The first speed may be such that the step of rotating the drum produces centrifugal G forces between 10 and 1000, preferably between 100 and 800, more preferably between 200 and 700, most preferably between 276.7 and 622.6. The second speed may be such that the step of rotating the drum produces centrifugal G forces between 0.05 and 10, preferably between 0.5 and 5, more preferably between 1 and 4, most preferably between and 1.77 and 3.98

A suitable set of equations for converting between rotational speed of the drum in RPM and G forces associated with rotating the drum at that speed (i.e. centripetal reaction force from the inner surface of the drum) is as follows. A suitable drum diameter is 990mm.

For a drum of inner radius r (m), rotating at R (rpm), with a washload of mass M (kg), and an instantaneous tangential velocity of the drum v (m/s), and taking g as the acceleration due to gravity at 9.81 m/s

Force = Mv²/r

Washload static weight = Mg v = 2TTTR/60

Hence, G = 4TT²r²R²/3600rg = 4TT²rR²/3600g = 1.118 x 10^"3rR² When, as is usually the case, r is expressed in centimetres, rather than metres, then: G = 1.1 18 x 10^"5rR² Hence, for a drum of radius 49 cm rotating at 800 rpm, G = 350.6.

Preferably the step of applying heat to the flow of air comprises passing the flow of air through a combustion chamber or an electric heater, or providing a supply of steam.

As with the first aspect of the invention, it is particularly advantageous to introduce and maintain a flow of air into the drum by drawing air into the cylindrical drum through the open front end and/or the closed rear end, and the associated steps and structure associated with that advantage are also applicable to the second aspect of the invention.

Also provided is an apparatus suitable for washing and drying a substance comprising: a housing having mounted therein a cylindrical drum rotatably mounted along a first axis about which it is configured to rotate under the influence of a drive;

a fan assembly for drawing air along a flow path passing through the cylindrical drum; a heater for raising the temperature of at least part of the air drawn along the flow path to provide an environment within the cylindrical drum at a drying temperature; and

a control system configured to cause the apparatus to:

i) operate in a wash cycle, in which the control system causes the apparatus to perform at least an extraction phase of the wash cycle that includes causing the cylindrical drum to rotate at a first speed thereby causing extracting wash water from the drum; and

ii) operate in a dry cycle, in which the control system causes the apparatus to perform at least an air-drying phase of the dry cycle that includes causing the cylindrical drum to rotate at a second speed that is slower than the first speed, causing the fan assembly to draw air along the flow path and causing the heater to raise the temperature of at least part of the air drawn along the flow path;

wherein the control system is configured to cause the apparatus to transition between operating in the wash cycle and operating in the dry cycle, wherein the control system is further configured to activate the fan assembly to induce a flow of air along the flow path and to activate the heater to raise the temperature of at least part of the air drawn along the flow path prior to completion of the extraction phase of the wash cycle.

The apparatuses described herein are preferably of the front-loading kind, with the access means disposed in the front of the apparatus. Preferably the access means is or comprises a door. It will be appreciated that, suitably, the drum has an opening aligned with the access means, through which opening said substrates are introduced into said drum.

The drum is preferably cylindrical, but other configurations are also envisaged, including for instance hexagonal drums. The inner surface of the drum is preferably a cylindrical inner surface (also described herein as a circumferential sidewall).

It is possible to facilitate the drying process by introducing solid particulate material, as described elsewhere herein. In operation of such a washer-dryer, agitation is provided by rotation of the drum and by the introduction of heated air. Thus, said apparatus additionally comprises means for circulating air within said housing means, and for adjusting the temperature therein. Said means may typically include, for example, a recirculating fan and an air heater. Additionally, sensing means may also be provided for determining the temperature and humidity levels within the apparatus, and for communicating this information to the control means.

In operation of the washer-dryer described above, during a typical cycle, cleaned garments containing residual moisture are first placed into the drum. The drum is caused to rotate and ambient or heated air is introduced via the perforations in the drum before the solid particulate material is added. During the course of agitation by rotation of the drum, water is caused to be removed from the garments by evaporation and a quantity of the solid particulate material falls through the perforations in the cage and into the second chamber of the apparatus. Thereafter, the solid particulate material is re-circulated via the recirculation means such that it is returned, in a manner controlled by said control means, to the cylindrical cage for continuation of the drying operation. This process of continuous circulation of the solid particulate material occurs throughout the drying operation until drying is completed.

On completion of the cycle, feeding of solid particulate material into the drum ceases but rotation of the drum continues so as to allow for removal of the solid particulate material. Air heating and re-circulation may also be stopped at this point. After separation, the solid particulate material is preferably recovered in order to allow for re-use in subsequent drying operations. Said separation of particulate material removes >99% of these particles, and typically removal rates approach, or actually reach, 100%.

Clearly, it is required that the perforations or apertures in the cylindrical wall of the drum should be sized so as to be at least the size of the largest dimension of the particles comprised in the solid particulate material, in order that these particles are able to exit from the drum. The dimensions of the apertures may be selected in line with the dimensions of the solid particles, so as to allow efficient ingress and transfer thereof. The one or more apertures are preferably larger than the largest dimension of the solid particles. Typically, the one of more apertures of the lifters have a smallest dimension of from about 1 mm to about 20 mm, preferably from about 1 mm to about 15 mm. Typically, the one or more apertures may have a diameter of from about 1 mm to about 10 mm, preferably from about 1 mm to about 8 mm, preferably from about 1 mm to about 6 mm. On completion of the drying cycle, addition of solid particulate material to the drum is ceased, but the rotation G and rotational speed are maintained at the same values of < 1 and low (40) rpm as in the drying cycle in order to effect the removal of particulate material.

Additionally, it has been demonstrated that re-utilisation of the particles in the manner described operates well, so that particles can be satisfactorily re-used in subsequent drying procedures. Indeed such re-utilisation offers further advantages in terms of energy efficiency, as heating the air naturally results in heating of the particulate media in the drying process. This heat then is retained by the particles on completion of a drying cycle and, hence, if the next drying cycle occurs within the time taken for the particles to cool down, there will be a transfer of this retained heat to that subsequent drying process. There is, therefore, an even greater level of drying efficiency achievable in the event that multiple drying cycles are run consecutively. This is, of course, applicable to both the domestic and industrial laundry sectors - but, most particularly, to the latter. Rapid turnaround of drying cycles and high load throughput are both key factors in this kind of drying operation in an industrial scenario.

The apparatus may further comprise the typical components present in apparatus suitable for the treatment of substrates with solid particulate material and treatment liquor as described in more detail hereinbelow. Preferably, the apparatus comprises a suitable drive means to effect rotation of the drum, and suitably a drive shaft to effect rotation of the drum. Preferably, the apparatus comprises heating means for heating the treatment liquor. Preferably, the apparatus comprises mixing means to mix the components of the treatment liquor. The apparatus may further comprise one or more spray means to apply a liquid, such as the treatment liquor or a rinsing liquid into the interior of the drum and onto the substrate during the treatment thereof. It will be appreciated that the apparatus suitably further comprises a control means programmed with instructions for the operation of the apparatus according to at least one treatment cycle. The apparatus suitably further comprises a user interface for interfacing with the control means and/or apparatus.

The apparatus of the present invention is preferably configured for the treatment of substrates (in a cleaning cycle and/or a drying cycle) with solid particulate material, optionally in the presence of a treatment liquor.

The solid particulate material preferably comprises a multiplicity of particles. Typically, the number of particles is no less than 1000, more typically no less than 10,000, even more typically no less than 100,000. A large number of particles is particularly advantageous in preventing creasing and/or for improving the uniformity of treating or cleaning of the substrate, particularly wherein the substrate is a textile.

Preferably, the particles have an average mass of from about 1 mg to about 1000 mg, or from about 1 mg to about 700 mg, or from about 1 mg to about 500 mg, or from about 1 mg to about 300 mg, preferably at least about 10 mg, per particle. In one preferred embodiment, the particles preferably have an average mass of from about 1 mg to about 150 mg, or from about 1 mg to about 70 mg, or from about 1 mg to about 50 mg, or from about 1 mg to about 35 mg, or from about 10 mg to about 30 mg, or from about 12mg to about 25 mg. In an alternative embodiment, the particles preferably have an average mass of from about 10 mg to about 800 mg, or from about 20mg to about 700mg, or from about 50 mg to about 700 mg, orfrom about 70 mg to about 600 mg from about 20mg to about 600mg. In one preferred embodiment, the particles have an average mass of about 25 to about 150 mg, preferably from about 40 to about 80 mg. In a further preferred embodiment, the particles have an average mass of from about 150 to about 500 mg, preferably from about 150 to about 300 mg.

The average volume of the particles is preferably in the range of from about 5 to about 500 mm³, from about 5 to about 275 mm³, from about 8 to about 140 mm³, or from about 10 to about 120 mm³, or at least 40 mm³, for instance from about 40 to about 500 mm³, or from about 40 to about 275 mm³, per particle. The average surface area of the particles is preferably from 10 mm² to 500 mm² per particle, preferably from 10mm² to 400mm², more preferably from 40 to 200mm² and especially from 50 to 190mm². The particles preferably have an average particle size of at least 1 mm, preferably at least 2mm, preferably at least 3mm, preferably at least 4 mm, and preferably at least 5mm. The particles preferably have an average particle size no more than 100mm, preferably no more than 70mm, preferably no more than 50mm, preferably no more than 40mm, preferably no more than 30mm, preferably no more than 20mm, preferably no more than 10mm, and optionally no more than 7mm. Preferably, the particles have an average particle size of from 1 to 20mm, more preferably from 1 to 10mm. Particles which offer an especially prolonged effectiveness over a number of treatment cycles are those with an average particle size of at least 5mm, preferably from 5 to 10mm. The size is preferably the largest linear dimension (length). For a sphere this equates to the diameter. For non-spheres this corresponds to the longest linear dimension. The size is preferably determined using Vernier callipers. The average particle size is preferably a number average. The determination of the average particle size is preferably performed by measuring the particle size of at least 10, more preferably at least 100 particles and especially at least 1000 particles. The above mentioned particle sizes provide especially good performance (particularly cleaning performance) whilst also permitting the particles to be readily separable from the substrate at the end of the treatment method.

The particles preferably have an average particle density of greater than 1 g/cm³, more preferably greater than 1.1 g/cm³, more preferably greater than 1.2g/cm³, even more preferably at least 1.25g/cm³ and especially preferably greater than 1.3g/cm³. The particles preferably have an average particle density of no more than 3g/cm³ and especially no more than 2.5g/cm³. Preferably, the particles have an average density of from 1.2 to 3g/cm³. These densities are advantageous for further improving the degree of mechanical action which assists in the treatment process and which can assist in permitting better separation of the particles from the substrate after the treatment.

The particles of the solid particulate material may be polymeric and/or non-polymeric particles. Suitable non-polymeric particles may be selected from metal, alloy, ceramic and glass particles. Preferably, however, the particles of the solid particulate material are polymeric particles. Preferably the particles comprise a thermoplastic polymer. A thermoplastic polymer, as used herein, preferably means a material which becomes soft when heated and hard when cooled. This is to be distinguished from thermosets (e.g. rubbers) which will not soften on heating. A more preferred thermoplastic is one which can be used in hot melt compounding and extrusion.

The polymer preferably has a solubility in water of no more than 1wt%, more preferably no more than 0.1wt% in water and most preferably the polymer is insoluble in water. Preferably the water is at pH 7 and a temperature of 20°C whilst the solubility test is being performed. The solubility test is preferably performed over a period of 24 hours. The polymer is preferably not degradable. By the words "not degradable" it is preferably meant that the polymer is stable in water without showing any appreciable tendency to dissolve or hydrolyse. For example, the polymer shows no appreciable tendency to dissolve or hydrolyse over a period of 24hrs in water at pH 7 and at a temperature of 20°C. Preferably a polymer shows no appreciable tendency to dissolve or hydrolyse if no more than about 1 wt%, preferably no more than about 0.1 wt% and preferably none of the polymer dissolves or hydrolyses, preferably under the conditions defined above.

The polymer may be crystalline or amorphous or a mixture thereof.

The polymer can be linear, branched or partly cross-linked (preferably wherein the polymer is still thermoplastic in nature), more preferably the polymer is linear.

The polymer preferably is or comprises a polyalkylene, a polyamide, a polyester or a polyurethane and copolymers and/or blends thereof, preferably from polyalkylenes, polyamides and polyesters, preferably from polyamides and polyalkylene, and preferably from polyamides.

A preferred polyalkylene is polypropylene.

A preferred polyamide is or comprises an aliphatic or aromatic polyamide, more preferably an aliphatic polyamide. Preferred polyamides are those comprising aliphatic chains, especially C4-C16, C4-C12 and C4-C10 aliphatic chains. Preferred polyamides are or comprise Nylons. Preferred Nylons include Nylon 4,6, Nylon 4, 10, Nylon 5, Nylon 5,10, Nylon 6, Nylon 6,6, Nylon 6/6,6, Nylon 6,6/6,10, Nylon 6, 10, Nylon 6, 12, Nylon 7, Nylon 9, Nylon 10, Nylon 10, 10, Nylon 1 1 , Nylon 12, Nylon 12,12 and copolymers or blends thereof. Of these, Nylon 6, Nylon 6,6 and Nylon 6,10, and particularly Nylon 6 and Nylon 6,6, and copolymers or blends thereof are preferred. It will be appreciated that these Nylon grades of polyamides are not degradable, wherein the word degradable is preferably as defined above.

Suitable polyesters may be aliphatic or aromatic, and preferably derived from an aromatic dicarboxylic acid and a C1-C6, preferably C2-C4 aliphatic diol. Preferably, the aromatic dicarboxylic acid is selected from terephthalic acid, isophthalic acid, phthalic acid, 1 ,4-, 2,5- , 2,6- and 2,7-naphthalenedicarboxylic acid, and is preferably terephthalic acid or 2,6- naphthalenedicarboxylic acid, and is most preferably terephthalic acid. The aliphatic diol is preferably ethylene glycol or 1 ,4-butanediol. Preferred polyesters are selected from polyethylene terephthalate and polybutylene terephthalate. Useful polyesters can have a molecular weight corresponding to an intrinsic viscosity measurement in the range of from about 0.3 to about 1.5 dl/g, as measured by a solution technique such as ASTM D-4603.

Preferably, polymeric particles comprise a filler, preferably an inorganic filler, suitably an inorganic mineral filler in particulate form, such as BaSCU. The filler is preferably present in the particle in an amount of at least 5wt%, more preferably at least 10wt%, even more preferably at least 20wt%, yet more preferably at least 30wt% and especially at least 40wt% relative to the total weight of the particle. The filler is typically present in the particle in an amount of no more than 90wt%, more preferably no more than 85wt%, even more preferably no more than 80wt%, yet more preferably no more than 75wt%, especially no more than 70wt%, more especially no more than 65wt% and most especially no more than 60wt% relative to the total weight of the particle. The weight percentage of filler is preferably established by ashing. Preferred ashing methods include ASTM D2584, D5630 and ISO 3451 , and preferably the test method is conducted according to ASTM D5630. For any standards referred to in the present invention, unless specified otherwise, the definitive version of the standard is the most recent version which precedes the priority filing date of this patent application. Preferably, the matrix of said polymer optionally comprising filler(s) and/or other additives extends throughout the whole volume of the particles. The particles can be spheroidal or substantially spherical, ellipsoidal, cylindrical or cuboid. Particles having shapes which are intermediate between these shapes are also possible. The best results for treatment performance (particularly cleaning performance) and separation performance (separating the substrate from the particles after the treating steps) in combination are typically observed with ellipsoidal particles. Spheroidal particles tend to separate best but may provide optimum treatment or cleaning performance. Conversely, cylindrical or cuboid particles separate poorly but treat or clean effectively. Spherical and ellipsoidal particles are particularly useful where improved fabric care is important because they are less abrasive. Spheroidal or ellipsoidal particles are particularly useful in the present invention which is designed to operate without a particle pump and wherein the transfer of the particles between the storage means and the interior of the drum is facilitated by rotation of the drum.

The term "spheroidal", as used herein, encompasses spherical and substantially spherical particles. Preferably, the particles are not perfectly spherical. Preferably, the particles have an average aspect ratio of greater than 1 , more preferably greater than 1.05, even more preferably greater than 1.07 and especially greater than 1.1. Preferably, the particles have an average aspect ratio of less than 5, preferably less than 3, preferably less than 2, preferably less than 1.7 and preferably less than 1.5. The average is preferably a number average. The average is preferably performed on at least 10, more preferably at least 100 particles and especially at least 1000 particles. The aspect ratio for each particle is preferably given by the ratio of the longest linear dimension divided by the shortest linear dimension. This is preferably measured using Vernier Callipers. Where a good balance between treating performance (particularly cleaning performance) and substrate care is required, it is preferred that the average aspect ratio is within the abovementioned values. When the particles have a very low aspect ratio (e.g. highly spherical particles), the particles may not provide sufficient mechanical action for good treating or cleaning characteristics. When the particles have an aspect ratio which is too high, the removal of the particles from the substrate may become more difficult and/or the abrasion on the substrate may become too high, which may lead to unwanted damage to the substrate, particularly wherein the substrate is a textile. According to a further aspect of the present invention, there is provided a method for treating a substrate (as part of a cleaning cycle and/or a drying cycle) comprising agitating the substrate with solid particulate material in the apparatus of the present invention, as described herein. Preferably, in the method of the present invention, the solid particulate material is re-used in further treatment procedures.

The method preferably comprises agitating the substrate with solid particulate material and a treatment liquor.

The method may comprise the additional step of rinsing the treated substrate. Rinsing is preferably performed by adding a rinsing liquid medium, optionally comprising one or more post-treatment additives, to the treated substrate. The rinsing liquid medium is preferably an aqueous medium, i.e. the rinsing liquid medium is or comprises water. In order of increasing preference, the rinsing liquid medium comprises at least 50wt%, at least 60wt%, at least 70wt%, at least 80wt%, at least 90wt%, at least 95wt% and at least 98wt% of water. More preferably, the rinsing liquid medium is water.

Thus, preferably, the method is a method for treating multiple batches, wherein a batch comprises at least one substrate, the method comprising agitating a first batch with solid particulate material, wherein said method further comprises the steps of:

(a) collecting said solid particulate material in the storage means;

(b) agitating a second batch comprising at least one substrate with solid particulate material collected from step (a); and

(c) optionally repeating steps (a) and (b) for subsequent batch(es) comprising at least one substrate.

The treatment procedure of an individual batch typically comprises the steps of agitating the batch with said solid particulate material in a treatment apparatus for a treatment cycle. A treatment cycle typically comprises one or more discrete treatment step(s), optionally one or more rinsing step(s), optionally one or more step(s) of separating the particles from the treated batch, optionally one or more extraction step(s) of removing treatment liquor from the treated batch, optionally one or more drying step(s), and optionally the step of removing the treated batch from the apparatus. In the method of the present invention, steps (a) and (b) may be repeated at least 1 time, preferably at least 2 times, preferably at least 3 times, preferably at least 5 times, preferably at least 10 times, preferably at least 20 times, preferably at least 50 times, preferably at least 100 times, preferably at least 200 times, preferably at least 300 times, preferably at least 400 at least or preferably at least 500 times.

The substrate may be or comprise a textile and/or an animal skin substrate. In a preferred embodiment, the substrate is or comprises a textile. The textile may be in the form of an item of clothing such as a coat, jacket, trousers, shirt, skirt, dress, jumper, underwear, hat, scarf, overalls, shorts, swim wear, socks and suits. The textile may also be in the form of a bag, belt, curtains, rug, blanket, sheet or a furniture covering. The textile can also be in the form of a panel, sheet or roll of material which is later used to prepare the finished item or items. The textile can be or comprise a synthetic fibre, a natural fibre or a combination thereof. The textile can comprise a natural fibre which has undergone one or more chemical modifications. Examples of natural fibres include hair (e.g. wool), silk and cotton. Examples of synthetic textile fibres include Nylon (e.g. Nylon 6,6), acrylic, polyester and blends thereof. As used herein, the term "animal skin substrate" includes skins, hides, pelts, leather and fleeces. Typically, the animal skin substrate is a hide or a pelt. The hide or pelt may be a processed or unprocessed animal skin substrate.

The treating of a substrate which is or comprises a textile according to the present invention may be a cleaning process or any other treatment process such as coloration (preferably dyeing), ageing or abrading (for instance stone-washing), bleaching or other finishing process. Stonewashing is a known method for providing textiles having "worn in" or "stonewashed" characteristics such as a faded appearance, a softer feel and a greater degree of flexibility. Stonewashing is frequently practiced with denim. Preferably the treating of a substrate which is or comprises a textile is a cleaning process. The cleaning process may be a domestic or industrial cleaning process.

As used herein, the term "treating" in relation to treating an animal skin substrate is preferably a tannery process, including colouring and tanning and associated tannery processes, preferably selected from curing, beamhouse treatments, pre-tanning, tanning, re-tanning, fat liquoring, enzyme treatment, tawing, crusting, dyeing and dye fixing, preferably wherein said beamhouse treatments are selected from soaking, liming, deliming, reliming, unhairing, fleshing, bating, degreasing, scudding, pickling and depickling. Preferably, said treating of an animal skin substrate is a process used in the production of leather. Preferably, said treating acts to transfer a tanning agent (including a colourant or other agent used in a tannery process) onto or into the animal skin substrate.

The treatment liquor referred to herein may comprise one or more treatment agent(s) which are suitable to effect the desired treating of the substrate.

Thus, a method according to the present invention which includes a cleaning process suitably comprises agitating the substrate with said solid particulate material and a treatment liquor comprising one or more treatment agents, wherein said treatment liquor is preferably a detergent composition comprising one or more of the following components: surfactants, dye transfer inhibitors, builders, enzymes, metal chelating agents, biocides, solvents, stabilizers, acids, bases and buffers. Similarly, the treatment liquor of a coloration process preferably comprises one or more dyes, pigments, optical brighteners and mixtures thereof.

The treatment liquor of a stone-washing process may comprise an appropriate stone- washing agent, as known in the art, for instance an enzymatic treatment agent such as a cellulase.

The treatment liquor of a tannery process suitably comprises one or more agent(s) selected from tanning agents, re-tanning agents and tannery process agents. The treatment liquor may comprise one or more colourant(s). The tanning or re-tanning agent is preferably selected from synthetic tanning agents, vegetable tanning or vegetable re-tanning agents and mineral tanning agents such as chromium (III) salts or salts and complexes containing iron, zirconium, aluminium and titanium. Suitable synthetic tanning agents include amino resins, polyacrylates, fluoro and/or silicone polymers and formaldehyde condensation polymers based on phenol, urea, melamine, naphthalene, sulphone, cresol, bisphenol A, naphthol and/or biphenyl ether. Vegetable tanning agents comprise tannins which are typically polyphenols. Vegetable tanning agents can be obtained from plant leaves, roots and especially tree barks. Examples of vegetable tanning agents include the extracts of the tree barks from chestnut, oak, redoul, tanoak, hemlock, quebracho, mangrove, wattle acacia; and myrobalan. Suitable mineral tanning agents comprise chromium compounds, especially chromium salts and complexes, typically in a chromium (III) oxidation state, such as chromium (III) sulphate. Other tanning agents include aldehydes (glyoxal, glutaraldehyde and formaldehyde), phosphonium salts, metal compounds other than chromium (e.g. iron, titanium, zirconium and aluminium compounds). Preferably, the tanning agents are substantially free from chromium-containing compounds.

One or more substrates can be simultaneously treated by the method of the invention. The exact number of substrates will depend on the size of the substrates and the capacity of the apparatus utilized.

The total weight of dry substrates treated at the same time (i.e. in a single batch orwashload) may be up to 50,000 kg. For textile substrates, the total weight is typically from 1 to 500 kg, more typically 1 to 300 kg, more typically 1 to 200 kg, more typically from 1 to 100 kg, even more typically from 2 to 50 kg and especially from 2 to 30 kg. For animal substrates, the total weight is normally at least about 50 kg, and can be up to about 50,000 kg, typically from about 500 to about 30,000 kg, from about 1000 kg to about 25,000 kg, from about 2000 to about 20,000 kg, or from about 2500 to about 10,000 kg. Preferably the treatment liquor is an aqueous medium, i.e. the treatment liquor is or comprises water. In order of increasing preference, the treatment liquor comprises at least 50wt%, at least 60wt%, at least 70wt%, at least 80wt%, at least 90wt%, at least 95wt% and at least 98wt% of water. The treatment liquor may optionally comprise one or more organic liquids including for example alcohols, glycols, glycol ethers, amides and esters. Preferably, the sum total of all organic liquids present in the treatment liquor is no more than 10wt%, more preferably no more than 5wt%, even more preferably no more than 2wt%, especially no more than 1 % and most especially the treatment liquor is substantially free from organic liquids.

The treatment liquor preferably has a pH of from 3 to 13. The pH of the treatment liquor can differ at different times, points or stages in the treatment method according to the invention. It can be desirable to treat (particularly to clean) a substrate under alkaline pH conditions, although while higher pH offers improved performance (particularly cleaning performance) it can be less kind to some substrates. Thus, it can be desirable that the treatment liquor has a pH of from 7 to 13, more preferably from 7 to 12, even more preferably from 8 to 12 and especially from 9 to 12. In a further preferred embodiment, the pH is from 4 to 12, preferably 5 to 10, especially 6 to 9, and most especially 7 to 9, particularly in order to improve fabric care. It may also be desirable that the treating of a substrate, or one or more specific stage(s) of a treatment process, is conducted under acid pH conditions. For instance, certain steps in the treatment of animal skin substrates are advantageously conducted at a pH which is typically less than 6.5, even more typically less than 6 and most typically less than 5.5, and typically no less than 1 , more typically no less than 2 and most typically no less than 3. Certain fabric or garment finishing treatment methods, for instance stone-washing, may also utilise one or more acidic stage(s). An acid and/or base may be added in order to obtain the abovementioned pH values. Preferably, the abovementioned pH is maintained for at least a part of the duration, and in some preferred embodiments for all of the duration, of the agitation. In order to prevent the pH of the treatment liquor from drifting during the treatment, a buffer may be used.

Preferably, the weight ratio of the treatment liquor to the dry substrate is no more than 20:1 , more preferably no more than 10: 1 , especially no more than 5: 1 , more especially no more than 4.5: 1 and even more especially no more than 4:1 and most especially no more than 3: 1. Preferably, the weight ratio of treatment liquor to the dry substrate is at least 0.1 :1 , more preferably at least 0.5:1 and especially at least 1 : 1. In the present invention, it is possible to use surprisingly small amounts of treatment liquor whilst still achieving good treatment performance (particularly cleaning performance), which has environmental benefits in terms of water usage, waste water treatment and the energy required to heat or cool the water to the desired temperature. More than one type of treatment liquor may be used during the methods of treating a substrate described herein. For example, a treatment liquor consisting of water may be added initially to the substrate in the drum prior to the introduction of solid particulate material. Subsequently, during agitation of the substrate with the solid particulate material, a treatment liquor comprising water and one or more treatment agents may be used.

Preferably, the ratio of particles to dry substrate is at least 0.1 , especially at least 0.5 and more especially at least 1 :1 w/w. Preferably, the ratio of particles to dry substrate is no more than 30: 1 , more preferably no more than 20: 1 , especially no more than 15: 1 and more especially no more than 10: 1 w/w. Preferably, the ratio of the particles to dry substrate is from 0.1 : 1 to 30: 1 , more preferably from 0.5: 1 to 20: 1 , especially from 1 : 1 to 15: 1 w/w and more especially from 1 :1 to 10:1 w/w.

The treatment method agitates the substrate in the presence of the solid particulate material. The agitation may be in the form of shaking, stirring, jetting and tumbling. Of these, tumbling is especially preferred. Preferably, the substrate and solid particulate material are introduced into the drum which is rotated so as to cause tumbling. The rotation can be such as to provide a centripetal force of from 0.05 to 1 G and especially from 0.05 to 0.7G. The centripetal force is preferably as calculated at the interior walls of the drum furthest away from the axis of rotation.

The solid particulate material is able to contact the substrate, suitably mixing with the substrate during the agitation.

The agitation may be continuous or intermittent. Preferably, the method is performed for a period of from 1 minute to 10 hours, more preferably from 5 minutes to 3 hours and even more preferably from 10 minutes to 2 hours.

The treatment method is preferably performed at a temperature of from greater than 0°C to about 95°C, preferably from 5 to 95°C, preferably at least 10°C, preferably at least 15°C, preferably no more than 90°C, preferably no more than 70°C, and advantageously no more 50°C, no more than 40°C or no more than 30°C. Such milder temperatures allow the particles to provide the afore-mentioned benefits over larger numbers of treatment cycles. Preferably, when several batches or washloads are treated or cleaned, every treating or cleaning cycle is performed at no more than a temperature of 95°C, more preferably at no more than 90°C, even more preferably at no more than 80°C, especially at no more than 70°C, more especially at no more than 60°C and most especially at no more than 50°C, and from greater than 0°C, preferably at least 5°C, preferably at least 10°C, preferably at least 15°C, preferably from greater than 0 to 50°C, greater than 0 to 40°C, or greater than 0 to 30°C, and advantageously from 15 to 50°C, 15 to 40°C or 15 to 30°C. These lower temperatures again allow the particles to provide the benefits for a larger number of treatment or wash cycles.

It will be appreciated that the duration and temperature conditions described hereinabove are associated with the treating of an individual batch comprising at least one of said substrate(s).

Agitation of the substrates with the solid particulate material suitably takes place in said one or more discrete treating step(s) of the aforementioned treatment cycle. Thus, the duration and temperature conditions described hereinabove are preferably associated with the step of agitating said substrate(s) with solid particulate material, i.e. said one or more discrete treating step(s) of the aforementioned treatment cycle.

Preferably, the method is a method for cleaning a substrate, preferably a laundry cleaning method, preferably a method for cleaning a substrate which is or comprises a textile. Thus, preferably, a batch is a washload. Preferably the washload comprises at least one soiled substrate, preferably wherein the soiled substrate is or comprises a soiled textile. The soil may be in the form of, for example, dust, dirt, foodstuffs, beverages, animal products such as sweat, blood, urine, faeces, plant materials such as grass, and inks and paints. The cleaning procedure of an individual washload typically comprises the steps of agitating the washload with said solid particulate material in a cleaning apparatus for a cleaning cycle. A cleaning cycle typically comprises one or more discrete cleaning step(s) and optionally one or more post-cleaning treatment step(s), optionally one or more rinsing step(s), optionally one or more step(s) of separating the cleaning particles from the cleaned washload, optionally one or more drying step(s), optionally one or more extraction step(s) of removing treatment liquor from the cleaned washload, and optionally the step of removing the cleaned washload from the cleaning apparatus.

Where the method is a cleaning method, the substrate is preferably agitated with said solid particulate material and a treatment liquor, preferably wherein the treatment liquor comprises a detergent composition. The detergent composition may comprise any one or more of the following components: surfactants, dye transfer inhibitors, builders, enzymes, metal chelating agents, biocides, solvents, stabilizers, acids, bases and buffers. In particular, the detergent composition may comprise one or more enzyme(s).

Where the method is a cleaning method, optional post-cleaning additives which may be present in a rinsing liquid medium include optical brightening agents, fragrances and fabric softeners.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a diagrammatic representation of a first flow path through Electrolux® Pronto® combination washer-dryer;

Figure 2 shows a diagrammatic representation of a second flow path through Electrolux® Pronto® combination washer-dryer; Figure 3 shows a front view of an apparatus according to the disclosure;

Figure 4 shows a cross-sectional view of the apparatus of Figure 3 through section X-X;

Figure 5 shows a front view of a first embodiment of the invention; and

Figure 6 shows a cutaway perspective view of the embodiment of figure 5; and

Figure 7 shows a cutaway perspective view of the embodiment of figure 5; and Figure 8 shows a front view of a second embodiment of the invention.

Preferred embodiments of a first aspect of the invention will now be described.

Figures 3 and 4 illustrate an apparatus (10) according to an aspect of the present disclosure. The apparatus (10) comprises a housing (20). The housing (20) comprises an upper portion (20a) and a lower portion (20b). The housing (20) comprises a rotatably mounted drum (40). The drum (40) may be in the form of a rotatably mounted cylindrical cage. In the arrangement shown in Figures 3 and 4, the drum is horizontally mounted in a casing or a tub (80) and is mounted in the upper portion (20a) of the housing. The tub (80) comprises a curved top portion (84) that circumferentially surrounds a portion of the drum (40). The tub (80) may comprise a first sidewall (not shown) and a second sidewall (not shown) extending from the curved portion (84) to the base of the tub.

The drum may have a capacity in the region of 50 to 7000 litres. A typical capacity for a domestic machine would be in the region of 80 to 140 litres and, for an industrial machine, this range would typically be from 170 to 2000 litres.

The drum (40) has apertures in its walls (not shown). The apertures allow the ingress and egress of treatment liquor and the solid particulate material. The drum may have perforated side walls. Alternatively, the drum may comprise apertures in the side wall and one or more lifters on the inside surface of the drum, in which the one or more lifters comprise a flow pathway that allows solid particulate material and treatment liquor to reach the aperture and exit the drum.

Rotation of the drum (40) is effected by use of drive means (95). The drive means (95) comprises electrical drive means in the form of an electric motor. The operation of the drive means (95) is effected by control means which may be operated by a user.

The base of the tub (80) includes a collector (88) located beneath the drum which functions to collect solid particulate material and treatment liquor that exits the drum.

In the arrangement shown in Figures 3 and 4, the unitary nature of the tub (80) enables the portion containing the drum (40) and the portion comprising the collector (88) to move together as one body in response to vibrations induced by rotation of the drum (40). The apparatus (10) comprises dampers (78) connected to the tub (80) to reduce the extent to which vibrations from the drum are transmitted to the housing (20). Alternatively (and as is the case for the embodiments shown in figures 5 to 8, for example, the collector (214) is affixed to the frame of the apparatus whilst the tub (80) (which is also connected to dampers (219) as previously described) is attached to the collector (214) by means of a rubber bellows.

In the particular arrangement shown in figures 3 and 4, the apparatus has a collar or hood (82) that projects out from the front face (22) of the housing (20) around part or all of the opening of the housing through which the drum (40) is accessible. The collar or hood (82) may extend from or be an integral part of the tub (80).

The collar or hood (82) comprises an aperture (90). The apparatus has a recirculation means comprising a flow pathway pipe (1 10) having an outlet (140) that defines a path between the collector (88) and a recirculation means separator (100). The flow pathway pipe is configured so that it is mounted in the housing and passes through the aperture (90) of the collar or hood (82). A pump (not shown) is arranged in the recirculation means so that it is able to pump treatment liquor and solid particulate material from the collector (88), along the flow pathway pipe (110) and onto the recirculation means separator (100).

The apparatus (10) comprises a door (60) to allow access to the interior of the drum (40). The door (60) is hingedly coupled or mounted to the front (22) of the housing (20). In an alternative arrangement (not shown) the door (60) may be hingedly coupled or mounted to a portion of the tub (80). The door (60) comprises a ring (66) and the ring (66) is adapted to hold the recirculation means separator (100) in position in the door (60). The ring (66) of the door comprises a drain channel (70) located at the bottom of the door (60). The channel (70) is arranged such that material that has passed through the recirculation means separator (100), such as treatment liquor, is able to exit the door through the drain channel (70) and flow into the collector (88).

The door is moveable between an open and a closed position. When the door (60) is in a closed position (as shown in Figures 3 and 4), the apparatus (10) is substantially sealed. When the door (60) is in an open position, the inside of the drum (40) is accessible. In the arrangement shown, when the door is in the closed position, the door abuts and makes a seal with the collar (82). In a typical treatment cycle using the apparatus (10), substrates to be treated (not shown) are first placed into the drum (40) and the door (60) is closed. An appropriate amount of treatment liquor (for example, water or water and an additional treatment agent) may be optionally added to the drum (40) via delivery means (not shown). Where the treatment liquor comprises water and a cleaning agent, the water may be pre-mixed with the cleaning agent prior to its introduction into the drum (40). However, typically, water is added first in order to suitably wet or moisten the substrate before further introducing any cleaning agent. The treatment liquor may be heated by a heater (not shown). The treatment cycle commences by rotation of the drum (40). The solid particulate material and optionally treatment liquor residing in the collector (88), which optionally can be heated to a desired temperature using a heater (not shown), is then pumped via the flow pathway pipe (1 10) into the drum (40), preferably via the recirculation means separator (100) as in the arrangement shown in Figures 3 and 4, where solid particles are propelled from the recirculation means separator (100) and through an outlet in the door and into the centre of the washload in the drum (40). During the course of agitation by rotation of the drum (40), treatment liquor falls or moves through apertures in the drum (40) and into the collector (88). Some solid particulate material may also fall or move through apertures in the side walls of the drum (40) and into the collector (88). Alternatively, lifters (not shown) disposed on the inner circumferential surface of the drum (40) can collect the solid particles as the drum (40) rotates and transfer the solid particles through an aperture in the side wall of the drum and into the collector (88). On transfer to the collector (88), the solid particulate material and treatment liquor flow down the feeder surfaces (14a and 14b) and are directed into the channel (12) of the collector (88). Solid particulate material is prevented from passing through the separator (1 1) and is directed towards the second outlet (8), from where the solid particulate material and treatment liquor enter the recirculation means and are pumped back to the drum (40), where they can be re-used in either a single treatment cycle or in one or more subsequent treatment cycles. The arrangement of the separator (1 1) within the channel (12) of the collector (88) decreases the residence time of the solid particulate material in the collector (88), which has the effect of increasing the quantity of solid particulate material in the drum during the treatment. Furthermore, by having a collector (88) comprising feeder surfaces (14a, 14b) and a channel (12), the quantity of treatment liquor required to enable solid particulate material to be recirculated in the apparatus can be significantly reduced.

Treatment liquor pumped from the collector (88) through the recirculation means separator (100) with the solid particulate material but which does not enter the drum (40) can be returned to the collector (88) via a drain (70) in the door (60).

Furthermore, treatment liquor can be removed from the collector (88) via the first outlet (6). Treatment liquor drained via the first outlet (6) can be sent to a drain as waste. Alternatively, treatment liquor drained via the first outlet (6) can be filtered to remove lint or other solid waste material from the substrate and then the treatment liquor can be re-used in either a single treatment cycle or in one or more subsequent treatment cycles. In a preferred arrangement, treatment liquor is removed from the collector (88) via the first outlet in the channel (12) of the collector (88) and is filtered to remove lint or other solid waste material from the substrate. The filtered treatment liquor is then reintroduced into the collector (88) via the nozzle (17a, 17b) and directed towards the lower portion (4) of the collector (88) in order to agitate solid particulate material in the lower portion of the collector (88) and hence encourage flow of the solid particulate material towards the second outlet (8). The apparatus (10) can perform a treatment cycle with, for example, the drum (40) rotating at from about 30 to about 40 rpm for several revolutions in one direction, then rotating a similar number of rotations in the opposite direction. This sequence can be repeated for as long as is required to complete the treatment, for example, for up to about 60 minutes. During this period, solid particulate material can be introduced and reintroduced to the drum (40) from the collector (88) in the manner as described above.

In an embodiment of the invention, the apparatus (10) shown in figures 3 and 4 is provided with components to facilitate a drying cycle. Generally speaking, these components include an air inlet, a heater, ducting to allow air to be drawn through the air inlet and burner and to pass into the drum, an exhaust opening in the tub and ducting to allow air to be drawn out of the drum through the exhaust opening and further ducting to allow air to pass the into external environment at an outlet. A fan assembly is mounted at the outlet to generate negative pressure and thereby draw air from inlet to the outlet. Figures 5 to 8 illustrate at least two embodiments of the invention with components to facilitate a drying cycle.

Figures 5 to 7 show a first such embodiment of a washer-dryer (200) of the present invention. The washer-dryer (200) comprises all of the features described above in connection with figures 3 and 4, together with the following features. An air inlet (shown generally at 201) is provided on a top wall of the washer-dryer (200). The air inlet (201) is provided with an air heater including a combustion chamber (202) and burner (203) which when called upon heats air drawn in through the air inlet to a temperature of up to 140°C. The air heater alternatively be an electric heater or a supply of steam. Ambient air passes through the air inlet (201) into the combustion chamber (202) where it is heated, and heated air then passes through air inlet ducting (204) that has a lower edge which conforms to the outer edge of door (60). In this embodiment, the air inlet ducting (204) is offset to the left of the door for reasons which will be described elsewhere herein.

The heated air is drawn from the air inlet ducting (204) through a front plate (207) mounted to the front wall of the washer-dryer (200). The plate has an aperture (209) through which air may pass into the front opening of drum (40). The plate (207) may be fixed to or an integral part of the collar or hood (82) mentioned above in connection with figures 3 and 4.

The washer-dryer (200) further comprises an exhaust (208) which is configured to draw air from within the drum (40) to an external environment. The exhaust (208) is coupled to an exhaust opening (211) within the tub (80) such that air may be drawn from within the drum (40) through perforations and/or apertures (not shown) in the cylindrical wall of the drum (40) to a space between the drum (40) and the tub (80), and from there through the exhaust opening (21 1) within the tub (80) to the exhaust (208). Within the exhaust (208), preferably adjacent the exhaust opening (211) there is a filter (213) for preventing solid particulate matter such as may optionally be used as part of a cleaning and/or drying cycle, and/or material such as lint or other waste material which results from the cleaning and/or drying process from passing through the exhaust (208), which can be an environmental and/or fire risk. At the mouth of the exhaust is a fan assembly (210) which generates a negative pressure to draw air along the flow path described above. An air outlet (215) is also provided.

Although the exhaust (208), fan assembly (210) and outlet (215) are shown extending outwardly from a sidewall of the washer-dryer (200), this need not be the case. Instead, the outlet may be located at any point on the housing of the washer-dryer, with the fan assembly (210) mounted within or upon the housing and the exhaust (208) leading from the fan assembly to the exhaust opening in the tub (80).

Also visible in figures 6 and 7 is a collector (214), which is akin to the collector 88 of the appliance shown in figures 3 and 4. Referring to figure 7, the collector (214) is coupled to the bottom of the tub (80) via an opening (216). It will be understood that at the end of a wash cycle (explained in more detail below with respect to the second aspect of the invention), the collector (214) may contain a quantity of wetted solid particulate matter and/or water that has not yet drained away. As explained above, during the drying phase in a typical washer-dryer, warm air will be drawn through the drum and tub, and out through an exhaust. A person of ordinary skill in the art would understand that the wetted solid particulate matter and/or water in the collector (214) would act as a heat sink, and that drawing warm air across the wetted solid particulate matter and/or water would most likely lead to evaporation and raise the water content of the warm air. Given that the goal of the washer-dryer is to utilize the flow of warm air to extract as much moisture from the contents of the drum as possible, any heat that passes from the flow of warm air to the collector (214) and any evaporation of the water in the collector will lead to inefficiency in the drying cycle by reducing the ability of the flow of warm air to extract moisture from the contents of the drum. For this purpose, although not shown in the drawings, a valve (preferably a butterfly valve) is located in the opening (216) between the collector (214) and the tub (80). The expectation of the inventors was that the efficiency of the drying cycle would drastically decrease if the valve between the collector (214) and the tub (80) were left open. However, because the arrangement described above (i.e. the arrangement that facilitates a flow path entering the drum through the open front end and/or the closed rear end and exiting the cylindrical drum through at least one aperture in the circumferential side wall of the drum) is so vastly improved compared with prior art arrangements, this was found not to be the case and no perceptible loss of efficiency was detected when leaving the valve between the collector (214) and the tub (80) open rather than closed.

The inventors have found that key to the efficiency of the drying cycle is the length of the flow path within the drum. Accordingly, in a first preferred variant (as illustrated in all of figures 5 to 8), the opening in the plate (207) is positioned in the plane of the plate (that is, the plane of the front of the washer-dryer) at approximately 330° to the vertically upward direction (i.e. at around the 1 1 o'clock position). In an equivalent second preferred embodiment (not shown), the opening in the plate (207) is positioned at approximately 30° to the vertically upward direction (i.e. at around the 1 o'clock position). These positions are preferred because they avoid the problem of how to place ducting and openings close to the hinge and handle portions of the door (60), which are typically found at the 90° and 270° positions. Where the opening is positioned to avoid the hinge and handle portions, it is able to be positioned further from the periphery of the drum and closer to the drum's axis, which avoids the problems described elsewhere herein with respect to the prior art. The 30° and 330° positions are also preferred because they are closer to the inlet and combustion chamber than, say positions between 90° and 270°. This facilitates introduction of a heated airflow into the drum (40) with minimal ducting and therefore minimal heat loss. It is also simpler to configure ducting to pass from the roof of the washer-dryer (where the air heater is located) to openings in the upper half of the plate (i.e. between 0° and 90°, or between 270° and 360°). In the first preferred variant (as illustrated), the exhaust opening (not shown) in the tub is positioned (when measured in the plane of the plate; that is, the plane of the front of the washer-dryer) at approximately 90° to the vertically upward direction (i.e. at around the 3 o'clock position). In the second preferred variant (not shown), the exhaust opening (not shown) in the tub is positioned (when measured in the plane of the plate; that is, the plane of the front of the washer-dryer) at approximately 270° to the vertically upward direction (i.e. at around the 9 o'clock position).

The effect of mounting an opening in the plate on one side of the washer-dryer (e.g. the 11 or 1 o'clock positions) to enable air to be drawn into the front of the drum, and an exhaust opening on the opposite side of the washer-dryer (e.g. the 3 or 9 o'clock positions, respectively) to enable air to be drawn out of the cylindrical wall of the washer-dryer, achieves two things. Firstly, compared with an exclusively axial flow, the arrangement lengthens the path through the drum along which air is drawn. Secondly, by introducing air through the open front of the drum rather than through the cylindrical wall, the problem of skirting is overcome.

Figure 8 shows an alternative embodiment of a washer-dryer (300). The components of the washer-dryer (300) are the same as for the embodiment shown in figure 5, except that the air inlet ducting (304) is positioned centrally over the door (60) rather than being offset to the left as with the figure 5 embodiment.

Despite the air inlet ducting (304) being positioned centrally over the door (60), the opening (not shown) in the plate of this embodiment is in the same position as for the earlier embodiments. However, it will be understood that an advantage of the air inlet ducting (304) in the embodiment of figure 8 is that the position of the opening can be changed without modifying the air inlet ducting (304). For instance, this air inlet ducting (304) would be suitable for use with a washer-dryer having an opening in the plate at 330° (i.e. the 1 1 o'clock position), or at 30° (i.e. the 1 o'clock position) or anywhere in between. It is feasible that ducting could be provided which surrounds the door in a hollow annulus shape, thereby being suitable for use irrespective of where the opening is located about the door.

Returning to the air inlet ducting (204) in the embodiment of figures 5 to 7, the advantage of setting this off to one side (to the left, as shown in the figures but the opposing side is also possible) is that it becomes possible to accommodate additional ducting to introduce other media into the drum, such as water, cleaning agents and/or the solid particulate matter described elsewhere herein. For example, in figures 5 and 6, a chute (217) is shown passing from the roof of the washer-dryer (200) and coupling to a collar or hood (shown in figures 3 and 4, ref 82) at the 0° (i.e. 12 o'clock) position. This chute (217) may be the flow pathway pipe (1 10) described above in connection with figures 3 and 4. Modifications of this aspect of the invention will occur to the skilled person based on the teaching herein. For example, notwithstanding the technical advantages described above, the opening to introduce a flow of air into the front and/or rear of the drum may be located anywhere that aligns with the drum itself. Likewise, notwithstanding the technical advantages described above, the exhaust opening may be located anywhere in the cylindrical wall of the tub. Other modifications to the embodiments shown in figures 3 to 8 will occur to the skilled person without departing from the scope of the present invention, as defined in the claims.

Preferred embodiments of a second aspect of the present invention, concerning the timing and/or order in which phases of the wash and dry cycles are performed, will now be described.

In what follows, the term 'wash cycle' will be used to refer to all phases of a cycle in which a washer-dryer operates to remove soiling from substrates. In general, a wash cycle will involve process steps of spraying the contents of the drum water and/or chemicals, tumbling the wetted contents of the drum, preferably together with solid particulate material, and extracting water and/or solid particulate material to an acceptable wet saturation percentage (typically around 60%) for the dry cycle. As described below, the extraction phase of the wash cycle involves spinning the drum at high speeds to remove water by forcing the substrates against the circumferential wall of the drum at high levels of centrifugal force.

In what follows, the term 'drying cycle' will be used to refer to all phases of a cycle in which a washer-dryer operates to dry the substrates that were wetted in the preceding wash cycle. In general, a drying cycle will involve process steps of removing water using heated air and reversing tumble steps to dry substrates to an acceptable dry retention percentage (-2%).

A typical order for phases of the wash cycle of a washer-dryer involving solid particulate material (e.g. beads) is as follows.

Wash Cycle # Brief description Drum Notes

speed

1 Tank Fill 30 liters of water for spraying

2 Spray 1 st rinse

3 Tank Fill 30 liters of water for spraying

4 Spray 2nd rinse

5 Tumble 60 rpm to gather clothes/towels in a 'donut' for bead introduction

6 Fill sump additional water as needed for transport water for beads

7 Initial beads 40 rpm first cleaning action

8 Beads and tank fill 40 rpm 2nd cleaning action and water for spraying

9 Beads and tank to sump 40 rpm 3rd cleaning action

10 Beads and tank fill 40 rpm 4th cleaning action

1 1 Beads and tank to sump 40 rpm 5th cleaning action

12 Drain and fill tank remove dirty water and fill tank

13 Extract 500 rpm to spin out water, dirt, bead separation

14 Spray 3rd rinse

15 Drain and fill tank remove dirty water and fill tank

16 Spray 4th rinse

17 Extract 750 rpm to spin out dirty water and bead separation

A typical order for phases of the drying cycle of the washer-dryer with the above-described wash cycle (or others) is as follows. Dry Cycle

In conventional washer-dryers such as the Electrolux® Pronto® combination washer-dryer, phase 18 (i.e. start dryer heater), which forms part of the dry cycle, will commence only once phase 17 (i.e. extract), which forms part of the wash cycle, has finished. Waiting for this to happen is time consuming and, the inventors have found, unnecessary.

According to an embodiment of the invention, a method of performing a wash and dry cycle comprises beginning the extract phase of the wash cycle at the same time as beginning the dry cycle - specifically the phases of starting the dryer heater. In practice, this means that the fan assembly and heater (not shown) are activated to begin drawing warm air into the drum (thereby pre-heating the drum and substrates) as soon as the motor begins to increase the rotational speed of the drum (e.g. to 750 rpm) as part of the (final) extract phase of the wash cycle.

Of course, a skilled person would appreciate that it is not essential for the fan assembly and heater to be activated at exactly the same time that the (final) extract phase of the wash cycle begins, and in some circumstances it may be advantageous to delay activation of the fan assembly and/or heater until a certain time after the beginning of the (final) extract phase of the wash cycle; i.e. a certain time after the motor begins to increase the rotational speed of the drum. For instance, it may be preferable to delay activation of the heater, or both the heater and the fan assembly, until a sufficient quantity of water has drained from the tub, or until only a certain quantity of water remains in the tub. However, it will be understood that the earlier in the (final) extract phase of the wash cycle the heater and the fan assembly are activated, the less time will be taken overall.

Example 1

Tests were performed on two washer-dryer machines to investigate the advantages of the inventions described herein.

A first test was performed on an Electrolux 'Pronto' WD4240. This machine was loaded with 26.4 Lbs (bone dry weight) of substrates, which had a wet weight of 44.1 Lbs. After the wash and drying cycles had been performed, the substrates had a finish weight of 27.0 Lbs, leaving 0.6 Lbs of water remaining. The drying time was 48 minutes and the total gas consumed to heat the air for the drying process was 18.730 cubic feet (Ft³). A second test was performed using a modified Electrolux 'Pronto' device incorporating the components described above with reference to the first aspect of the invention (using the configuration shown in embodiment of figures 5 to 7) and the second aspect of the invention. This modified machine was loaded with 55.0 Lbs (bone dry weight) of substrates, which had a wet weight of 88.9 Lbs. After the wash and drying cycles had been performed, the substrates had a finish weight of 56.2 Lbs, leaving 1.2 Lbs of water remaining. The drying time was 28 minutes and the total gas consumed to heat the air for the drying process was 40.420 cubic feet (Ft³).

As can be seen, the drying time for the second test (28 minutes) is significantly faster than the drying time for the first test (43 minutes) despite drying a significantly heavier load (88.9 Lbs wet weight, compared with 44.1 Lbs) and removing significantly more water (32.7 Lbs compared with 17.2 Lbs). The water removal rate observed in the second test was calculated to be 1.17 Lbs/min, compared to 0.36 Lbs/min in the first test. Although the second test consumed more gas than the first test (40.420 Ft³ compared with 18.730 Ft³), it only exhibited a slightly lower burner efficiency of 3,095 BTU/Lb.water compared with 2,730 BTU/Lb.water for the first test.

Features described herein in conjunction with a particular aspect or example of the disclosure are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. As used herein, the words "a" or "an" are not limited to the singular but are understood to include a plurality, unless the context requires otherwise.

Claims

1. An apparatus suitable for drying a substance, said apparatus comprising:

a housing having mounted therein:

(ii) a fan assembly configured to draw air along a flow path passing through the cylindrical drum; wherein the flow path enters the cylindrical drum through the open front end and/or the closed rear end and exits the cylindrical drum through the at least one aperture.

2. The apparatus of claim 1 , further comprising a plate coaxially aligned with the cylindrical drum, the plate having at least one opening, the flow path entering the cylindrical drum by passing through the at least one opening in the plate.

3. The apparatus of claim 2, wherein the plate is mounted on the housing such that the at least one opening in the plate is positioned, in a radial direction extending from the axis, between the axis and the inner periphery of the cylindrical drum.

4. The apparatus of claim 3, wherein at least a portion of the at least one opening in the plate occupies a position situated, in a radial direction extending from the axis, between

5% and 95% of the distance between the axis and the inner periphery of the cylindrical drum, preferably between 25% and 75%, more preferably between 30% and 60%.

5. The apparatus of any of claims 2 to 4, wherein at least a portion of the at least one opening in the plate occupies a position situated, in a circumferential direction about the axis, between 180° and 360° in a clockwise direction from vertically upwards, preferably between 270° and 360°, more preferably between 300° and 330°.

6. The apparatus of any of claims 2 to 5, wherein a ducting portion is mounted to the plate and is coupled to an air intake such that the flow path passes from the air intake through the ducting portion to the at least one opening in the plate.

7. The apparatus of claim 6, further comprising a source of heat at the air intake configured to supply a flow of heated air drawn along the flow path through the air intake.

8. The apparatus of claim 7, wherein the source of heat is one of a combustion chamber, an electrical heater and a source of steam.

9. The apparatus of any of claims 2 to 8, wherein the housing further comprises a door coaxially aligned with the cylindrical drum, wherein the plate and the ducting portion at least partially surround the door.

10. The apparatus of claim 9, when dependent on claim 7 or 8, wherein the source of heat is mounted to a roof of the housing, and wherein the plate and the ducting portion at least partially surround an upper portion of the door.

1 1. The apparatus of claim 8 or claim 9, wherein the innermost periphery of the plate and the innermost periphery of the ducting portion, in a radial direction extending toward the axis, conform to the shape of an outermost periphery of the door, in a corresponding direction.

12. The apparatus of claim 1 1 , wherein the innermost peripheries of the plate and the ducting portion and the outermost periphery of the door are at least partially arcuate.

13. The apparatus of claim 12, wherein the door is circular.

14. The apparatus of any preceding claim, wherein the housing has mounted therein a tub within which the cylindrical drum is rotatably mounted, the tub comprising an exhaust opening through which air is drawn by the fan assembly after passing through the cylindrical drum.

15. The apparatus of claim 14, further comprising a filter mounted across the exhaust opening.

16. The apparatus of any preceding claim, wherein the housing further comprises a front wall and a rear wall separated from the front wall along the first axis by one or more sidewalls and a roof, wherein the fan assembly is mounted to one of the front wall, rear wall, a sidewall or the roof, and wherein the flow path exits the housing through said front wall, rear wall, sidewall or roof.

17. The apparatus of claim 16, when dependent on claim 14 or 15, further comprising ducting between the exhaust opening and the fan assembly.

18. The apparatus of any of claims 14 to 17, wherein one or both of the exhaust opening and the fan assembly occupies a position situated, in a circumferential direction about the axis, between 0° and 180° in a clockwise direction from vertically upwards, preferably between 30° and 150°, more preferably between 60° and 120°, most preferably 90°.

19. The apparatus of any one of claims 14 to 18, wherein at least a portion of the exhaust opening occupies a position situated, in a circumferential direction about the axis, between 90° and 270° away from at least a portion of the at least one opening in the plate, preferably between 120° and 240°, more preferably between 150° and 210°, most preferably 180°.

20. The apparatus of any preceding claim suitable for drying a substance using a solid particulate material, wherein the apparatus comprises means for introducing the solid particulate material into the cylindrical drum, and wherein the cylindrical drum additionally comprises at least one opening passing through the circumferential wall or a component mounted thereon, wherein the opening is larger than the particle size of the solid particulate material and configured to facilitate transfer of said solid particulate material out of the cylindrical drum.

21. The apparatus of any preceding claim, further comprising a collection chamber mounted beneath the cylindrical drum for the collection and storage of water that drains from the cylindrical drum and/or, when dependent on claim 20, the solid particulate material transferred out of the drum.

22. The apparatus of claim 20 or 21 , wherein the solid particulate material has a particle size of between 1 mm and 50mm.

23. The apparatus of any one of claims 2 to 22, further comprising a filter mounted across the at least one opening in the plate.

24. The apparatus of claim 21 , further comprising a valve, preferably a butterfly valve, situated between the collection chamber and the cylindrical drum.

25. The apparatus of claim 24, further comprising a control system configured cause the value to move between open and closed positions, and to actuate the fan assembly to cause air to be drawn along the flow path.

26. The apparatus of claim 25, wherein the control system is configured to actuate the fan assembly to cause air to be drawn along the flow path whilst the valve is in its open position.

27. A method of drying a substance within a cylindrical drum having an open front end and a closed rear end separated from the front end along an axis by a cylindrical wall having at least one aperture passing through the circumferential wall, the method comprising: rotating the drum about the axis; and

drawing air through the cylindrical drum along a flow path which enters the cylindrical drum through the open front end and/or the closed rear end and exits the cylindrical drum through the at least one aperture passing through the circumferential wall.

28. The method of claim 27, wherein the step of drawing air through the cylindrical drum comprises passing air through at least one opening in a plate that is coaxially aligned with the cylindrical drum.

29. The method of claim 28, wherein the step of passing air through at least one opening comprises passing air into the cylindrical drum at a position between the axis and the inner periphery of the drum in a radial direction extending from the axis.

30. The method of claim 29, wherein the step of passing air through at least one opening comprises passing air into the cylindrical drum at a position between 5% and 95% of the distance between the axis and the inner periphery of the cylindrical drum, preferably between 25% and 75%, more preferably between 30% and 60% in a radial direction extending from the axis.

31. The method of any of claims 28 to 30, wherein the step of passing air through the at least one opening comprises passing air into the cylindrical drum between 180° and 360°, preferably between 270° and 360°, more preferably between 300° and 330° in a circumferential direction about the axis.

32. The method of claim 28, wherein the step of drawing air through the cylindrical drum comprises passing air from an air intake through a ducting portion coupled between the air intake and the plate, then to the at least one opening in the plate.

33. The method of claim 32, further comprising heating air drawn through the air intake.

34. The method of claim 33, wherein the step of heating air comprises heating air in a combustion chamber or an electrical heater, or providing a supply of steam at the air intake.

35. The method of any of claims 27 to 34, wherein the step of drawing air through the cylindrical drum comprises drawing air through an exhaust opening in a tub mounted within the housing.

36. The method of any of claims 37 to 35, wherein the step of drawing air through the cylindrical drum comprises drawing air using a fan assembly mounted to one of a front wall, rear wall, sidewall or roof of the housing.

37. The method of claims 35 or 36, wherein the step of drawing air through the cylindrical drum comprises drawing air through one or both of the exhaust opening and the fan assembly at a position situated between 0° and 180°, preferably between 30° and 150°, more preferably between 60° and 120°, most preferably 90°, in a circumferential direction about the axis,.

38. The method of any one of claims 27 to 38, further comprising actuating the fan assembly to cause air to be drawn along the flow path whilst a valve, preferably a butterfly valve, between a collection chamber and the cylindrical drum is in an open position.

39. The method of any one of claims 27 to 38, comprising introducing a solid particulate material into the cylindrical drum to facilitate drying of the substance, separating the solid particulate material from the substance though at least one opening passing through the circumferential wall or a component mounted thereon.

40. A method of operating an apparatus for use in washing and drying a substance, the method comprising:

introducing wash water into a drum comprising a substance;

operating the apparatus in a wash cycle, including a step of operating the apparatus in an extraction phase of the wash cycle, the extraction phase comprising at least: rotating the drum at a first speed and thereby extracting wash water from the drum;

operating the apparatus in a dry cycle, including a step of operating the apparatus in an air-drying phase of the dry cycle, the air-drying phase comprising at least:

41. The method of claim 40, wherein the step of introducing a flow of air into the drum begins at the beginning of the extraction phase of the wash cycle.

42. The method of claim 40 or 41 , wherein the step of introducing a flow of air into the drum is preceded by applying heat to the flow of air to raise the temperature of the flow of air to at least 80°C, preferably at least 100°C, preferably at least 120°C, preferably at least 140°C.

43. The method of claim 42, wherein the drying temperature is between 40°C and 140°C, preferably between 50°C and 120°C, more preferably between 60°C and 100°C, most preferably between 70°C and 80°C.

44. The method of any one of claims 40 to 43, wherein the first speed is such that the step of rotating the drum produces centrifugal G forces between 10 and 1000, preferably between 100 and 800, more preferably between 200 and 700, most preferably between 276.7 and 622.6.

45. The method of any one of claims 40 to 44, wherein the second speed is such that the step of rotating the drum produces centrifugal G forces between 0.05 and 10, preferably between 0.5 and 5, more preferably between 1 and 4, most preferably between and 1.77 and 3.98

46. The method of claim 42 or 45, wherein the step of applying heat to the flow of air comprises passing the flow of air through a combustion chamber or an electric heater, or providing a supply of steam.

47. The method of any of claims 40 to 46, wherein the steps of introducing and maintaining a flow of air into the drum each comprise drawing air into the cylindrical drum through the open front end and/or the closed rear end.

48. The method of claim 47, wherein the step of drawing air into the cylindrical drum comprises passing the flow of air into the drum at a point between the first axis and the inner periphery of the cylindrical drum in a radial direction.

49. The method of claim 48, wherein the step of drawing air into the drum comprises passing the flow of air into the drum at a point between 5% and 95% of the distance between the axis and the inner periphery of the cylindrical drum, preferably between 25% and 75%, more preferably between 30% and 60%, in a radial direction extending from the axis.

50. An apparatus suitable for washing and drying a substance comprising:

a housing having mounted therein a cylindrical drum rotatably mounted along a first axis about which it is configured to rotate under the influence of a drive;

a fan assembly for drawing air along a flow path passing through the cylindrical drum; a heater for raising the temperature of at least part of the air drawn along the flow path to provide an environment within the cylindrical drum at a drying temperature; and a control system configured to cause the apparatus to:

i) operate in a wash cycle, in which the control system causes the apparatus to perform at least an extraction phase of the wash cycle that includes causing the cylindrical drum to rotate at a first speed thereby causing extracting wash water from the drum; and ii) operate in a dry cycle, in which the control system causes the

apparatus to perform at least an air-drying phase of the dry cycle that includes causing the cylindrical drum to rotate at a second speed that is slower than the first speed, causing the fan assembly to draw air along the flow path and causing the heater to raise the temperature of at least part of the air drawn along the flow path; wherein the control system is configured to cause the apparatus to transition between operating in the wash cycle and operating in the dry cycle, wherein the control system is further configured to activate the fan assembly to induce a flow of air along the flow path and to activate the heater to raise the temperature of at least part of the air drawn along the flow path prior to completion of the extraction phase of the wash cycle.

51. The apparatus of claim 50, wherein the control system is configured to activate the fan assembly to induce a flow of air along the flow path and to activate the heater to raise the temperature of at least part of the air drawn along the flow path at the beginning of the extraction phase of the wash cycle.

52. The apparatus of claims 50 or 51 , wherein the drying temperature is between 40°C and 140°C, preferably between 50°C and 120°C, more preferably between 60°C and 100°C, most preferably between 70°C and 80°C.

53. The apparatus of any one of claims 50 to 52, wherein the first speed is such that, in use, rotation of the drum produces centrifugal G forces between 10 and 1000, preferably between 100 and 800, more preferably between 200 and 700, most preferably between 276.7 and 622.6.

54. The apparatus of any one of claims 50 to 53, wherein the second speed is such that, in use, the rotation of the drum produces centrifugal G forces between 0.05 and 10, preferably between 0.5 and 5, more preferably between 1 and 4, most preferably between 1.77 and 3.98.

55. The apparatus of any one of claims 50 to 54, wherein the heater comprises one of a combustion chamber, an electric heater and a supply of steam.

56. The apparatus of any one of claims 50 to 55, wherein the cylindrical drum comprises an open front end and a closed rear end, and wherein the apparatus further comprises ducting through which the flow path may pass such that air flowing along the flow path enters the cylindrical drum through the open front end and/or the closed rear end.

57. The apparatus of claim 56, wherein the ducting is configured such that air flowing along the flow path enters the cylindrical drum between the axis and the inner periphery of the cylindrical drum in a radial direction extending from the axis.

58. The apparatus of claim 57, wherein the ducting is configured such that air flowing along the flow path enters the cylindrical drum between 5% and 95% of the distance between the axis and the inner periphery of the cylindrical drum, preferably between 25% and 75%, more preferably between 30% and 60%, in a radial direction extending from the axis.