WO2012049482A1

WO2012049482A1 - Autoclave

Info

Publication number: WO2012049482A1
Application number: PCT/GB2011/051947
Authority: WO
Inventors: Julian Parry
Original assignee: Julian Parry
Priority date: 2010-10-12
Filing date: 2011-10-11
Publication date: 2012-04-19
Also published as: GB201017175D0

Abstract

An autoclave comprising: (i) an outer pressure vessel (1); (ii) a rotatable inner vessel (2) substantially coaxially arranged within said outer pressure vessel and rotatable about the common axis, said inner vessel comprising an outer solid wall (4) and an inner perforated wall (6); (iii) entry means (21) for delivering material into a space (24) defined within said inner perforated wall of the rotatable inner vessel; (iv) exit means (22) for recovering solid material from the space defined within said inner perforated wall of the rotatable inner vessel; (v) means (31) for recovering liquid from a space between the outer solid wall and the inner perforated wall of the rotatable inner vessel; (vi) means (11) for rotating the inner vessel; and (vii) means for supplying gas under pressure to the outer pressure vessel and the rotatable inner vessel.

Description

Autoclave

The present invention relates to an autoclave and in particular, an air supported high speed self-drying autoclave.

Background of the Invention

The international approach to waste management has developed over the years.

As time has passed, governments around the world have moved towards the concept of achieving zero waste.

Autoclaving waste is well-known in the art. The autoclaved output created using conventional autoclaves may be used to create methane in a wet anaerobic process. This wet process leaves around 20% of the original mass to be consigned to landfill. This is incompatible with new government strategies which seek to achieve zero waste.

In response to government initiatives a number of technologies have emerged including that known as JTP, described in WO2009/101393 (PCT application No. PCT/GB2009/000369). The JTP process seeks to dry the organic output from an autoclave to create a dried fuel with the drying process taking place entirely after the treated waste mass has been ejected from the autoclave with and including free water.

In pursing the development of that technology, the applicant has appreciated the need for further developments in autoclave design, technology and operation. These developments in autoclave design are aimed at providing an autoclave that is capable of carrying out an efficient process and that is able to remove at least some free water from the autoclaved mass before it is ejected from the autoclave.

Summary of the invention

According to the present invention there is provided an autoclave comprising:

(i) an outer pressure vessel;

(ii) a rotatable inner vessel substantially coaxially arranged within said outer pressure vessel and rotatable about a common axis, said inner vessel comprising an outer solid wall and an inner perforated wall;

(iii) entry means for delivering material into a space defined within said inner perforated wall of the rotatable inner vessel;

(iv) exit means for recovering solid material from the space defined within said inner perforated wall of the rotatable inner vessel;

(v) means for recovering liquid from a space between the outer solid wall and the inner perforated wall of the rotatable inner vessel;

(vi) means for rotating the inner vessel; and

(vii) means for supplying gas under pressure to the outer pressure vessel and the rotatable inner vessel.

The rotatable inner vessel effectively forms a 'basket' within the autoclave of the invention. It is able effectively to spin so that water leaves the material being autoclaved under centrifugal force. Accordingly the autoclave of the present invention is able to accelerate the drying process of autoclaved waste materials by separating free water from the autoclaved waste mass before that waste mass is ejected from the autoclave.

Although rotation of autoclaves is known, the usual engineering approach used in the prior art comprised the use of a rotating pressure vessel with all the physical engineering complications that implied. Alternatively, as described for example in

WO2007/079968, the pressure vessel is maintained stationary whilst a perforated inner tube rotates within it. In this instance, the pressure vessel itself acts as a collector of liquid released by the waste. However, the pressure vessel and the bearings and other working parts such as bearings that are open to the pressure vessel are subject to contamination by any waste that passes through the perforations in the inner tube, which can cause corrosion and break-downs in operation.

In order to simplify that aspect of the necessary engineering and to give effect to the purpose of the present invention the structure of the autoclave is substantially different from those used in the prior art. The pressure vessel involved in the present invention held is suitably held in a fixed in position, on a solid frame secured to a structurally suitable base. Accordingly, the pressure vessel itself does not rotate.

Nevertheless rotation of the waste mass is provided so as to obtain efficient waste treatment within an inner rotating vessel within the pressure vessel. All waste including liquid waste remains contained within the inner rotating vessel and so problems of contamination of the pressure vessel itself is minimised. Furthermore, the autoclave has a plurality of walls thus minimising the risk of catastrophic explosions that are sometimes seen with "single skin" autoclaves. Furthermore, the provision of an inner vessel allows external vessel to be insulated containing heat losses and increasing efficiency.

The autoclave is be provided with means for introducing gas such as steam, hot air or other gas under pressure into the rotatable inner vessel in order to effect the autoclave process. In the autoclave of the invention, there is further provided a means for feeding gas such as air or another gas under pressure into a gap formed between the rotatable inner vessel and the pressure vessel.

In a particular embodiment, the autoclave comprises means for balancing the pressure within the outer pressure vessel the rotatable inner vessel. In particular, this means is arranged to allow for substantial equalisation of the gas pressures within the outer pressure vessel and the rotatable inner vessel. This ensures that the strain on the vessels is kept to a minimum, thus reducing the chance of vessel failure that could lead to an explosion.

The entry means for delivering material into a space defined within said inner perforated wall of the rotatable inner vessel and exit means for recovering solid material from the space defined within said inner perforated wall of the rotatable inner vessel may take various forms as illustrated hereinafter. In general, the entry means will comprise an opening in the pressure vessel that allows access to the interior of the inner pressure vessel. Some form of materials hopper that is able to deliver material into the autoclave through the may be provided. Similarly, the exit means and the recovery means for liquid may comprise an opening or series of openings that allow materials within the inner rotatable vessel to pass out of the inner rotatable vessel though the outer pressure vessel. These openings suitable cooperate with for instance a series of pipes or receiving vessels to allow recovery of material that has been treated in the autoclave. In a particular embodiment, any openings within the autoclave in particular those associated with entry and exit means are sealable, for example using closure means such as pressure doors or closure plates, so that the autoclave can be sealed during operation. The closure means should be able to withstand the pressures and pressure changes that take place within the autoclave during operation thereof, and examples of suitable means include those where the closure means are held in place by rams or pistons including hydraulically operated rams or pistons, as illustrated in the examples given hereinafter. They need to be accurately positioned to ensure that pressure resistant seals can be achieved. This may suitably be achieved by using directing means such as rails or tracks along which the closure means may be directed, suitably held in the correct orientation on support means such as trolleys.

In a particular embodiment, the autoclave further comprises (viii) means for producing a reduced pressure or vacuum within the outer pressure vessel and the rotatable inner vessel. The provision of such means is particularly useful when the autoclave is intended for use in the treatment of domestic waste for instance in the JTP system, since it provides a means to allow any bags present in the autoclave to be burst open for instance in a preliminary step, as described hereinafter. Such means may comprise conventional gas evacuation means such as vacuum pumps that are connected to the appropriate spaces within the vessel by pipes or valves. However, in the context of an autoclave, reduced pressures may also be induced by applying cold liquid such as water to a steam filled vessel, so that the steam condenses, thus reducing the pressure in the vessel.

In the autoclave of the present invention, rotation of the waste mass under treatment is achieved by adding a rotating cylindrical rotating inner vessel mechanism inside the pressure vessel. As mentioned above, the inner perforated wall within the rotatable inner vessel defines a permeable basket within the rotatable inner vessel that is rotatable with that vessel. In use, waste to be treated is introduced into the space within the 'basket' within the inner rotatable vessel.

During the latter stages of treatment the operation of the mass the present invention allows the free water - the aqueous phase - to be separated from the non aqueous treated waste mass - the solid phase - before both the solid phase and the aqueous phase of the treated mass are ejected separately from the pressure vessel by segregated routes.

This separation is made possible by constructing the cylindrical rotatable inner vessel as a twin walled structure. The inner wall is perforated to form a basket structure as described above. Perforations are such that liquid may pass through this inner wall leaving the majority of the treated solid mass retained within the space within the basket of the inner rotating vessel.

Furthermore the structure of the rotating inner vessel within the pressure vessel used in the present invention is designed to protect the interior of the pressure vessel from the extremes of humidity and temperature variation experienced by other conventional autoclaves. This is achieved by ensuring all moisture is retained within the inner rotating vessel. The outer solid wall of the inner rotatable vessel ensures that liquid does not leak into the outer pressure vessel.

This means that the interior of the outer pressure vessel can, in particular embodiments, be insulated against the loss of energy in the form of heat.

In these embodiments, the energy required to be used by the autoclave may be reduced since the insulation reduces heat exchange with the surroundings. In particular, protection of the outer pressure vessel from internal temperature and humidity

fluctuations may be achieved by covering the internal surface of the pressure vessel with an appropriate thickness of insulation for example in the form of a layer of insulating material. The performance of the insulation layer is suitably protected or enhanced by providing an air filled gap between the outer wall of the central rotatable vessel which is impervious and the inner face of the insulation layer. The air filled gap provides further insulation against heat loss from the inner vessel. Furthermore, it allows expansion and contraction of the structural parts of the rotatable vessel mechanism to proceed freely within the pressure vessel without causing physical disruption to that mechanism.

However, in other embodiments, the structure of the internal rotatable vessel mechanism itself is provided with means such as expansion joints that are arranged to allow for such expansion and contraction of the structural parts of the rotatable vessel mechanism to proceed freely within the pressure vessel without causing physical disruption to that mechanism.

In use, the pressures within various parts of the autoclave of the present invention will vary from time to time. In a particular embodiment, means are provided to allow the pressures in these various parts to be balanced or co-ordinated to avoid damage to the mechanisms involved. In particular, these means are arranged to ensure that the pressures within different compartments within the pressure vessel are equal at all times to avoid damage.

Controlling the pressure of the gas within the gap between the outer pressure vessel and the inner rotating vessel is particularly useful for maintaining the pressure balance required throughout the pressure vessel. The gas pressure within this gap is therefore suitably made controllable so that it can be coordinated with the operational pressure of the air or steam or other gas within the central rotatable vessel. Suitable pressure control means will be known in the art and will generally be located externally of the pressure vessel although monitoring means that feeds information to the pressure control means may be provided in or on the pressure vessel. Suitably, the pressure of the gas, such as air or another gas, in this gap is arranged so that it exactly matches the operational pressure of the air or steam within the inner rotatable vessel at all times during the cycle.

In a particular embodiment, means for directing fluids in particular liquids ejected through the inner perforated wall are provided in the inner rotatable vessel. In particular, such means comprise structural members such as fins or pipes that are provided in the gap between the inner perforated wall and the outer wall of the rotatable vessel, arranged to capture and direct fluids drained or ejected from the basket formed by the inner perforated wall. Suitably the structural members or pipes are arranged helically around the rotatable inner vessel between the solid outer wall and the basket formed by the inner perforated wall and rotate with the vessel. A helical arrangement of these pipes or structural members around the basket within the rotating inner vessel allows absorption of any expansion or contraction that occurs within the structural framework made by the pipes or structural members. The helical design also reduces the torque on the joints between the structural members and other parts of the inner rotating vessel such, but not exclusively, runways, twisted cages or collars as described hereinafter.

Mechanical means of directing materials such as fins are optionally also provided within the basket defined by the inner perforated wall of the rotatable inner vessel and arranged to ensure that the waste mass or liquid within the basket is evenly distributed during the treatment process.

According to a further aspect, the invention provides a method for autoclaving material, said method comprising introducing said material, in particular waste material, through the entry means of an autoclave as described above, heating the autoclave to the desired temperature and pressure using for instance air and/or steam, rotating said inner rotatable vessel at a sufficient speed to cause liquid within the material to pass through the perforated inner wall under centrifugal pressure, recovering liquid from the space between the outer solid wall and perforated inner wall of the inner rotatable vessel and recovering solid material recovered through the exit means of the autoclave.

Suitably, in a separate phase of the treatment process, the inner rotatable vessel is rotated so as to mix liquid with the solid waste mass prior to the application of sufficient rotation to cause the liquid to pass through the perforated inner wall under centrifugal pressure. This additional step ensures that the material in the inner vessel is fluid enough to allow it to pass along the vessel at this point.

Liquid is suitably recovered into the structural members such as fins or pipes that are provided in the gap between the inner perforated wall and the outer wall of the rotatable vessel, and may then be transferred into a piped network arranged outside the pressure vessel for recovery purposes.

Throughout this process, as discussed above, the pressure within the gap between the rotatable inner vessel and the outer pressure vessel is controlled so that it is substantially equivalent or the same as the air/steam pressure within the inner rotatable vessel.

In a particular embodiment of the present invention, during part of each process cycle the operational gas pressure inside and outside the inner rotatable vessel is varied by external means. That pressure may be lowered to a negative pressure below external ambient air pressure or raised to a high pressure. The normal pressure range would be 0.3 bar to 6.0 bar, for example from 0.4bar to 6.0bar. The normal temperature range would be between -10 centigrade and plus 160 degrees centigrade.

As the gas pressure within the inner rotatable vessel is varied, the ambient pressure within the gap between the rotatable inner vessel and the outer pressure vessel is also varied to match the gas pressure within the rotating inner vessel. This is achieved in various ways. For example, it may be achieved by allowing gases to be spontaneously sucked from the gap outside the inner rotating vessel into the space within the inner rotating vessel. This equalling of reduced pressures may be achieved by way of a non- return valve positioned in the external piped network connecting between valves each directly connected to the air gap and the inner vessel. In the case of increasing pressures, the desired result may be achieved by supplying into the gap between the inner vessel and the outer pressure vessel, a compressed gas the pressure of which is equal to the pressure of any gas within the inner rotating vessel. Control of the gas supply in this instance can be achieved using control devices that are conventional in the art.

In a typical cycle, the autoclave vessel is first evacuated to form a vacuum or reduced pressure therein for example using the means (viii) discussed above, and subsequently steam is introduced to bring the vessel quickly to high temperatures and pressures. This rapid change of temperature and pressure can effectively explosively decompose materials exposed to it. Thus for instance, in the case of domestic waste, contained within containers such as bags such as plastic bags, the application of the vacuum in the surrounding vessel will cause any air in the bags to expand and burst open. If this is not achieved during this step, then the rapid change of temperature and pressure on entry of the steam will cause the bags to fail, thus releasing the contents for treatment in the process.

In a particular embodiment, any sealable openings into the autoclave, in particular any such openings that cooperate with the entry means or exit means, are enclosed within a pressure tube that is fixed to the end of the outer pressure vessel. The pressure tube themselves are suitably sealable, for example using sealing means such as pressure doors or closure plates, that may be held in place by clamps or other fixing means. In a convenient arrangement, operation of these sealing means is co-ordinated with that of the closure means for the autoclave, for instance they may use common rail or track systems, so that the autoclave and the pressure tubes are opened and closed together. These tubes provide effectively "safety chambers against any failures of the entry or exit means. Conveniently other elements of the mechanism such as the rotation means and bearings etc. associated with this are housed contained within one of these pressure tubes as they are then more easily available for maintenance.

Such tubes may be provided on any autoclave, and such autoclaves form a further aspect of the invention.

In a particular embodiment, the autoclave of the invention is suitably operated as part of a system comprising a plurality of autoclaves, in particular two such autoclaves which operate as a co-ordinated pair. In this way, gases and heated vented from one autoclave may be directed to another autoclave which would be operated on a different but complementary timescale.

Detailed Description of the Invention

The invention will now be particularly described by way of example with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a section through an autoclave in accordance with the present invention;

Figure 2 is a perpective view of a Savaran disc used in the autoclave of Figure 1;

Figure 3 is an exploded perspective view of the exterior body of an autoclave pressure vessel of the invention including additional safety zones added at each end thereof, with units of the loading and unloading mechanisms moved for clarity purposes;

Figure 4 is a detailed exploded perspective view of the drive and closure arrangements within the additional safety zones of the device of Figure 3;

Figure 5 is a detailed perspective view of the arrangement for securing the pressure doors with the additional safety zones;

Figure 6 is an exploded end view of the inner rotatable vessel and end tube with the rotating drive mechanism;

Figure 7 is a perspective side view of the inner rotatable vessel and rotating drive of Figure 6;

Figure 8 is a perspective view of the modified savaran dish used in the embodiment of Figures 3 to 6;

Figure 9 is a detailed exploded perspective view of the arrangement of the rotary drive mechanisms, pressure doors, drive drums and closure plates set within the additional safety zones, with the end cone removed for clarity;

Figure 10 is an end view along the inner rotatable vessel;

Figure 11 is a perspective view of a loading arrangement used in an embodiment of the invention;

Figure 12 illustrates a rail arrangement, useful in the entry or exit means of an autoclave embodying the invention; and

Figure 13 shows a pair of autoclaves suitable for co-ordinated operation.

The autoclave of Figure 1 comprises a pressure vessel (1) that is of a cylindrical shape, closed with a pressure resistant dome or cone at each end thereof.

The system would usually operate with two such vessels acting in pairs in which case they may be arranged for example as shown in Figure 13.

Each such vessel will be of designed dimensions calculated to accommodate the throughput of waste mass required taking into account its availability required treatment time-scales and bulk density.

Whilst in operation the pressure vessel (1) is tilted at an angle with respect to the horizontal plane with one end thereof elevated above the other in the vertical plane.

The elevated end (70) is used as the input point for any new supply of raw waste. The waste is often contained in a bag which is suitably made of degradable material. The lowered end (80) of the pressure vessel (1) is used for the unloading of treated waste.

Each pressure vessel (1) is modular and is provided with a plurality of substantial flanges (7) secured together in a manner that allows the pressure vessel (1) to be provided in demountable sections thereby allowing the insertion of a central treatment inner rotatable vessel (2) and to facilitate transport, construction and maintenance.

The pressure vessel (1) is mounted upon a fixed support frame (60) of adequate designed structural capacity.

Each vessel (1) is suitably mounted within a frame (60) such that the central axis (61) through the length of the pressure vessel (1) forms an included angle with a horizontal plane below the vessel. That included angle would normally be in the range of not less than 15 degrees and not more than 45 degrees.

Each pressure vessel (1) is lined with a layer of insulating materials (1 A) that covers the whole internal surface of the pressure vessel (1).

The internal void within each pressure vessel (1) is largely filled with an inner rotatable vessel (2), although a space (3) is provided therebetween. The body of each inner rotatable vessel (2) is made up of two concentric cylindrical walls comprised of an inner wall (6) and an outer wall (4). The inner wall (6), as well as the outer wall (4), is constructed of a corrosion resistant material of designed thickness calculated to withstand the static and dynamic forces it can be expected to experience in service. The inner wall (6) is perforated with a plurality of orifices of a suitable form, size and shape so that the inner wall effectively defines a 'basket' structure. These perforations connect a void space (24) within the inner rotatable vessel (2) with the inter wall void space between the inner wall (6) and the outer wall (4).

The inner wall (6) of the inner rotating vessel (2) is further provided with a plurality of expansion joints (6A). These ensure that the physical expansion and contraction of the structure of the inner rotating vessel (2), due to the temperature of the process is absorbed and accommodated within the structure.

The maximum diameter of the cylindrical inner rotatable vessel (2) occurs at a point that is equidistant from each end thereof. That maximum diameter gradually diminishes towards each end thereof such that the inner rotatable vessel (2) is provided with circular open ends at each end of the inner rotatable vessel (2) that are smaller in diameter than the largest diameter of the inner rotating vessel (2). The tapering structure of the inner rotatable vessel (2) allows the inner rotatable vessel to fit within the domed pressure vessel (1) and also ensures that the pressure on the doors provided at the ends as described further below is kept low.

These circular open ends of the inner rotatable vessel (2) are each secured and sealed to a collar (20) encircling and secured to the materials feed tube (21,22) at the upper end and lower ends of the inner rotatable vessel (2) respectively. Each materials feed tube (21, 22) is a cylindrical tube constructed of robust corrosion resistant materials of suitable wall thickness, length and diameter to accommodate waste material entering the rotatable vessel (2) in the case of tube 21, and treated material leaving the vessel in the case of tube 22. The diameter of the materials feed tubes (21, 22) is equal to the smaller diameter of the inner rotatable vessel (2) at each end thereof.

Helically arranged vanes (65) are arranged along the inner wall (6) to provide a material directing arrangement within the innermost space (24) of the rotating inner vessel (2). These direct waste material from the upper inlet end of the vessel (2) to the lower exit end as the vessel rotates.

The position of the central axis of each materials feed tubes (21 22) coincides exactly with the central axis of the inner rotatable vessel (2).

A series of thrust bearings (8), supported on the hollow collar (20) are provided to support the inner perforated wall (6) in the region of the feed tubes (21,22). Each such material feed tube (21 22) is encircled by the stout hollow collar (20) at the point where the perforated wall (6) meets the materials feed tubes (21 22). The hollow collar (20) is constructed of corrosion resistant material of sufficient section and strength to support the calculated loads that thrust bearings (8) are reasonably expected to experience.

Each sealed thrust bearing (8) is capable of resisting all forces that develop along or parallel to the central axis of the inner rotatable vessel (2) including those forces imparted by the mass of the waste and treatment services loaded into the an inner rotatable vessel (2), when the pressure vessel (1) is tilted to its elevated operational angle with respect to the horizontal plane below. Savaran dishes (17, 19) are provided at the upper and lower ends respectively of the inner rotatable vessel (2). The thrust bearings (8) are interposed between the collar (20) and the end of central out stand tubes (16,18) that forms part of the associated savaran dish (17,19) (see also Figure 2).

An inter- wall space lies between the inner wall (6) and the outer wall (4) of the inner rotatable vessel (2). The inter wall space is partially occupied by a plurality of support tubes (5) that are manufactured from corrosion resistant structurally sound materials. These support tubes (5) maintain the separation between the inner wall (6) and the outer wall (4) of the inner rotatable vessel (2). They may also serve to direct the flow of liquid that enters the inter wall space. The support tubes (5) are each formed into a wound helix that appears circular when viewed along the central axis (61) of the inner rotatable vessel (2). The internal diameter of the helix is equal to the outer diameter of the inner wall (6) of the inner rotatable vessel (2) at any point along the length of the inner rotatable vessel (2).

There are suitably a plurality of such support tubes (5), for example about 20 such tubes at any given point along the length of the rotatable vessel (2), positioned within the inter-wall space.

The helix formation can be created by a succession of individual support tubes, each connected to its neighbour at an end thereof to form a continuous helix of such tube (5). In this case, each support tube is suitably joined to the adjoining tube by mechanical means including but not exclusively overlapping tubular ferrules fitted internally or externally to the support tubes, each such mechanical connection being constructed of materials that are compatible with the structural support tubes (5).

In an alternate formation, each of these support tubes (5) may be formed to adopt the profile of a two dimensional ellipse.

Each end of each support tube (5) is secured and sealed to the relevant hollow collar (20), usually but not exclusively by corrosion resistant welding.

The interior of each support tube is ventilated via perforations (not shown) in the hollow collar (20). Each such perforation is centred upon the position of the abutment of each helical support tube (5). The hollow centre of each hollow collar (20) is separately ventilated by suitably sized perforations in the wall of the hollow collar (20) drilled through the face of the hollow collar (20) that is exposed to the inter-wall space. The inter-wall space (5 A) is enclosed on the outer face by the solid outer wall (4) made of a corrosion resistant material of a suitable thickness. Each end of the outer wall (4) is linked to a savaran dish (17, 19) by way of a bearing (9).

The shape of each savaran dish (17, 19) is detailed in fig 2. and features a central out stand tube (16,18) rising through the interior of the cup like section of the savaran dish (17, 19). The base of each savaran dish is (17,19) is fixed or positively secured in a fixed position to a domed or cone shaped end of the pressure vessel (1).

The outer wall (4) of the inner rotatable vessel (2) is provided with an expansion joint (4A). The expansion joint (4A) is covered by a stout corrosion resistant bearing plate (35) that encircles the outer wall (4) of the inner rotatable vessel (2). The plate 35 may comprise a composite that allows it also to support bolted structures (not shown) that hold the structural tubes 5 in position.

The bearing plate (35) acts as a runway for a plurality of jockey wheels (36) that are each supported individually upon a fluid operated piston assembly (37) that penetrates the pressure vessel (1). The point of penetration of the pressure vessel (1) is sealed to resist all operating pressures found within the pressure vessel (1) by the insertion of an engineered piston assembly (37) designed for the purpose.

Each piston assembly (37) is secured to the pressure vessel (1) in an equidistant distribution set out around the circumference of the pressure vessel (1) and the inner rotatable vessel (2). Each fluid operated piston (37) is connected to a piped network (38) capable of being appropriately pressurised in a manner that ensures the plurality of jockey wheels (36) set out around the circumference of the inner rotatable vessel (2) support the inner rotatable vessel (2) by means of the bearing plate (35).

The outer wall (4) of the inner rotatable vessel (2) is connected to each savaran dish (17, 19) by means of a sealed bearing (9) that allows rotation of the outer wall (4) with respect to the fixed savaran dish (17, 19) throughout a geometric plane set at right angles to the central axis (61) of the inner rotatable vessel (2).

The materials feed tubes (21, 22) attached to the inner wall (6) of the inner rotatable vessel (2) passes through the central out stand tube (16, 18) of the savaran dish (17, 19). The shortest distance across the space formed between the outer wall face of the materials feed tube (21) and the central out stand tube (16, 18) of the savaran dish (17, 19) is arranged to be exactly equal at all points around the circumference of the materials feed tube (21).

Within that space are fitted a plurality of seals. Specifically, there is fitted around the materials feed tube (21, 22) in a position close to the thrust bearing (8), an inner seal (10) with an outer seal (12) nearer the opposite open end of the materials feed tube (21). In between the seals (10 and 12) is fitted a circular rotary drive mechanism (11). Such a rotary drive mechanism (11) is fitted to each materials feed tubes (21, 22) at each end of the inner rotatable vessel (2).

Each rotary drive mechanism (11) is powered by an external energy source that may optionally be driven by pressurised fluids or an electric motor including but not exclusively a linear motor.

The thrust of the rotation developed by the rotary drive mechanism (1 1) is conveyed to the walls (4 and 6) of the inner rotatable vessel (2) by means of its attachment to the materials feed tubes (21) provided at each end of the inner rotatable vessel (2). To achieve that purpose the outer face of the circular rotary drive mechanism (1 1) that describes the largest circumference of that mechanism is securely fixed to the inside face of the savaran out-stand pipe (16, 18). The inside face of the circular rotary drive mechanism (1 1) is securely fixed to the outer face of the materials feed tubes (21 22).

The rotary drive mechanism (1 1) uses an external energy source to provide a means of rotation that may be transferred to the body of the inner rotatable vessel (2) such that the thrust provided by the rotary drive mechanism (1 1) is centred about the long axis (61) through the centre of the inner rotatable vessel (2) with a force that is capable of rotating the inner rotatable vessel (2) at by a variety of speeds, usually within the range 15 rpm to above 50 rpm. even when the inner rotatable vessel (2) is filled with a wetted autoclaved waste mass.

The speed and direction of rotation of the inner rotatable vessel (2) is controlled by applying controls to the amount of energy passed from the external energy supply to the rotary drive mechanism (11). The direction of rotation is controlled by manipulating the polarity of the electrical supply or the direction of the fluid supply passing through the rotary drive mechanism (11). In this way the speed of rotation of the outer wall (4) of the inner rotatable vessel (2) can be finely controlled in either direction. In this arrangement, the Savarn dishes (17, 19) act as the fixed end of the otherwise rotating inner vessel 2.

Moving on to consider the gas flow mechanisms that are used in the autoclave, it is well known that conventional autoclaves are normally operated by a combination of manipulating the gas pressure within the pressure vessel (1) and replacing air with steam. The temperature of the steam is directly related to the pressure created within the pressure vessel (1). In the course of treating materials in the autoclave of the present invention, there is a need to apply various services or conditions to the interior of the pressure vessel (1) including at various times, optionally a vacuum or reduced pressure, steam pressure, compressed air and drainage. These services are suitably each provided by independent external systems.

The external systems are connected to the pressure vessel (1) by a plurality of dedicated pipe networks which operates through a plurality of piped connections (31, 40, 41, 43). Each of those connections is controlled by a plurality of valves including vacuum control valves (45) (46) (47), steam control valves (50) (52) (53) and

compressed air control valves (54). The air control valve (54) also acts as an air pressure relief valve.

Free water or liquids accumulated in the lower savaran dish (19) can be drained by means of a piped connection (31) that is controlled by a computer controlled valve (32). The piped connection (31) can also apply vacuum to the rotating inner vessel (2) by means of external valve (53) linked to the external source of vacuum.

Each such control valve is separately situated within the appropriate piped network and each may be operated by hand but more usually operated by external computer control.

In order to load the illustrated autoclave with materials intended for autoclave treatment, the pressure vessel (1) is fitted with a cylindrical input tube (71). The input tube (71) is secured and sealed to the elevated end (70) of the pressure vessel (1). The input tube 71 is a cylinder, stoutly constructed of materials that are resistant to corrosion and treatments. The central axis of the input tube (71) is arranged to be coincident with central axis of the inner rotatable vessel (2). One end of the input tube (71) is closed by a circular plate (72) secured at right angles to the central axis of the input tube (71). The other end of the input tube (71) is secured to the pressure vessel (1) in such a way that the central axis of the input tube (71) is coincident with the centre of an opening (73) formed in the elevated end (70) of the pressure vessel (1).

The input tube (71) is provided with a cylindrical pressure door (74) centred upon the central axis (61) of the input tube (71). The door (74) is provided with support wheels (75) that impinge upon support rails secured within the inside of the input tube (71).

Support wheels (75) positively support both the pressure door (74) and the rotary drive mechanism (90) by way of the rails. The rails (79) are securely fixed to within the input tube (71). Such an arrangement is required to guide the door (74) into position accurately and to provide the rotary drive mechanism (90) with a secure base against which to rotate so as to prevent any rotation of either the door (74) and/or its supporting wheels (75).

The door (74) is manufactured to be capable of sealing the opening (73) on the pressure vessel (1) in way that can resist and contain the internal pressures developed within the pressure vessel (1) during a treatment operation. It is positively lockable for instance to the pressure vessel (1) to avoid rotation thereof. The door (74) is mounted upon a hydraulically operated piston (77). The hydraulic piston (77) is mounted through the centre of the circular plate (72) that closes one end of the input tube (71). In order to facilitate loading of the autoclave, the pressure doors (74) may be Opened or closed' by being withdrawn from or moved towards the pressure vessel 1 within the cylindrical input tube (71) using the piston (77). However, any suitable mechanical means may be used for this purpose including but not exclusively, hydraulically operated or pneumatically operated rams (77).

The input tube (71) is manufactured to contain the forces applied by the hydraulic ram (77) required to resist and contain the pressures developed in the pressure vessel (1) during operation of the present invention.

At a convenient point upon the outer upper face of the cylindrical input tube (71), there is an input hopper (78) mounted with its central axis (61) set vertically. The position of the input hopper (78) on the input tube (71) allows sufficient distance along the input tube (71) for the door (74) to be withdrawn from any area of the input tube (71) that lies between the input opening (73) and any part of the input tube (71) that is connected with the input hopper (78). A delivery scoop (69) is provided within the input tube (71) and arranged to pass through the materials feed tube (21) into the void (24) within the inner rotatable vessel.

In order to unload materials that have received autoclave treatment, the pressure vessel (1) is fitted with a cylindrical output tube (81). The output tube (81) is secured and sealed to the lowered end (80) of the pressure vessel (1). The output tube 81 is a cylinder stoutly constructed of corrosion resistant materials and treatments. The central axis of the output tube (81) is arranged to be coincident with central axis of the inner rotatable vessel (2).

One end of the output tube (81) is closed by a circular plate (82) secured at right angles to the central axis (61) of the output tube (81). The other end of the output tube (81) is secured to the pressure vessel (1) in such a way that the central axis of the output tube (81) is coincident with the centre of an opening (83) formed in the lowered end (80) of the pressure vessel (1).

The output tube (81) is provided with a cylindrical pressure door (84) centred upon the central axis (61) of the output tube (81). The door (84) is provided with a system of support wheels (85) that impinge on support rails secured within the inside of the output tube (81). The rails are securely fixed to and within the output tube (81) and arranged to guide the door (84) into position accurately. Furthermore, the rails provide the rotary drive mechanism 93 with a secure base against which to rotate so as to prevent any rotation of either the door (84) and/or the supporting wheels (85).

The lower pressure door (84) is manufactured to be capable of sealing the opening (83) on the pressure vessel (1) in way that can resist and contain the internal pressures developed within the pressure vessel (1) during a treatment operation. The door (84) is mounted upon connected to a hydraulically fluid operated piston (87). The hydraulic piston (87) is mounted through the centre of the circular plate (82) that closes one end of the output tube (81).

The output tube (81 ) is manufactured to contain the forces applied by the hydraulic piston (87) required to resist and contain the pressures developed in the pressure vessel (1) during operation of the present invention. At a convenient point upon the lower outer face of the cylindrical output tube (81), there is an output chute (88) mounted with its central axis set vertically. The position of the output chute (88) on the output tube (81) allows sufficient distance along the output tube (81) for the door (84) to be withdrawn from any area of the output tube (81) that lies between the output opening (83) and any part of the output tube (81) that is connected with the output chute (88).

In order to facilitate unloading, the pressure doors (84) may be Opened or closed' by being withdrawn from or moved towards the pressure vessel 1 by the hydraulic piston (87) although any suitable mechanical means, such as but not exclusively, hydraulically operated or pneumatically operated rams may be used.

An alternative embodiment of an autoclave of the invention and elements of this are illustrated in Figures 3-12. Whilst the majority of the embodiment is similar to that described above, in this embodiment the regions of the entry means and the exit means have been modified to incorporate safety chambers that further measures to prevent explosions as a result of failure of the autoclave.

In particular, in this embodiment the features of the outer pressure vessel (1) and the rotatable inner vessel (2) are retained. As shown in Figure 3, the outer pressure vessel (1) is, in this case, comprised of a plurality of modules (IE) (Figure 4), each held together by means of flanges (7) that are locked into place. Each section is provided with a series jockey wheels and jockey wheel piston assemblies (37) that support the inner rotatable vessel as described in relation to Figure 1. In this embodiment, the inner vessel (2) may also be made in a similar modular fashion (Figure 6 and 7).

It should be appreciated that whilst some Figures 4-12 illustrate the arrangements at one end of the autoclave only, a similar arrangement will be present at the other end of the autoclave also.

In this embodiment, the rotary drive mechanisms (11) are supplemented or replaced by drive mechanisms (105, 106) located outside the main pressure vessel (1) and located within extensions of the loading and unloading tubes (71C, 81C). In this case, the end plates of the input and output tubes are modified to form cone shaped plates (72A, 82A). The delivery scoop (69) is omitted in its entirety as is the fixed waste feed hopper 78. The fixed feed hopper (78) is replaced with an articulated waste hopper (78 A) mounted upon a fulcrum (78B) (Figure 4).

Also in this embodiment, a pressure tube (15) (Figure 5) suitably manufactured of high tensile steel sheet and of appropriate thickness and diameter to suit the particular autoclave requirements is provided around each of the upper and lower openings (73, 83) of the pressure vessel (1), external to that vessel. For instance, the high tensile steel may be 32mm thick with an internal diameter of approximately 1.5 metres. The cylinder (15) is provided with a machined ring (15 A) at an end thereof constructed of a material matching the properties of the material used in the manufacture of the main barrel of the vessel (1) and suitably welded in position.

The machined ring (15 A) shall be of sufficient size in section to allow a smooth face (15B) of sufficient width to be created such that with the pressure door 74, 84 (Figure 4) closed against provides a means of adequately sealing the atmosphere inside the autoclave from the atmosphere outside the autoclave irrespective of any differences in pressure between those atmospheres.

At another end thereof the pressure tube (15) is fitted a flange (15C) of a material matching the properties of the material used in the manufacture of the body of the tube (15) . The flange (15C) shall be of sufficient size section and strength to resist the forces generated and applied from within and without the pressure vessel (1). The flange (15C) will generally be welded to the end of the tube (15). The flange (15C) is provided with a plurality of perforations through which a plurality of securing bolts may pass thus evenly securing the pressure tube (15) to a pressure cone (IB) (Figure 4).

The pressure cone (IB) is secured to the pressure vessel (1) by means of a plurality of bolts, together capable of resisting all the internal forces that may develop within the pressure vessel (1). These securing bolts shall each be secured to and/or through a conversion ring (1C) in a manner which from time to time allows the pressure cone to be removed from the body of the pressure vessel (1) to facilitate construction and maintenance (Figure 4). The conversion ring (1C) shall be welded securely to the adjacent module (IE) of the main pressure vessel (1) (Figure 3).

In this embodiment, the savaran dish (17) shall be formed to, match the interior shape profile of the pressure cone (IB) such that the savaran dish may be maintained approximately 200 mm away from the inner surface of the pressure cone (1C) to allow for a layer of insulation 1 A to be provided between the pressure cone (IB) and the savaran dish (17) (Figure 8). The savaran dish (19) at the other end of the inner rotatable vessel (2) is suitably of a similar design, although the spout may be modified if necessary to ensure that it can be fitted to the relevant parts. Also in this embodiment, the internal rotary drive mechanism (11) and the thrust bearings (8) may be omitted. The rotary drive mechanism (11) may additionally be replaced with angled roller bearings (13) (Figure 5), held between pairs of support rings

(14) by means of seals (10A, 12A). The bearings (13) support rings (14) and seals (10A, 12 A) are mounted on the materials feed tubes (21, 22) but are arranged outside of the pressure vessel (1) and contained within the pressure tubes (15) which are mounted on and securely fixed to the coned or domed ends (IB) at each end of the pressure vessel (1).

The bearings (13) are set between support rings (14) and seals (10A, 12A) in manner designed to support the materials feed tubes (21, 22) in all three dimensions. To achieve such support the bearings (13) may contain roller bearings angled at 45 degrees to the central (longitudinal) axis of the materials feed tubes (21, 22) in order to provide both lateral support to the material feed tubes (21 22) and support any reaction to thrust forces developed along the axis of the inner rotatable vessel (2). The bearings (13) are maintained in position by the support rings (14). However, the support rings (14) are mechanically attached to the pressure tube (15) allowing the materials feed tubes (21, 22) to spin freely though 360 degrees.

The material feed tubes (21, 22) are supported within the relevant pressure tubes

(15) . Each is fitted with a collar (20) at an end thereof. The collar (20) encircles the material feed tubes (21, 22) to support them The collar (20) is also connected with and secured to the ends of the structural support tubes (5) forming the framework of the inner rotating vessel (Figure 9).

In this embodiment of the present invention the structural support tubes (5) are bent during manufacture in two dimensions to form a twisted cage (26). The structural tubes (5) converge on the outer diameter of the collar 20. The angle of depression at this point in the vertical plane would be approximately of 45 degrees. The angle of deflection in the horizontal plane would be approximately 45 degrees also.

When fully assembled, the twisted cage (26) would be largely positioned within a savaran dish (17, 19). As described above, it may be connected to a succession of short structural tubes together forming a structural framework made of such structural tubes (5) occupying the space between the inner wall (6) and the outer wall (4) of the inner rotating vessel (2). Each of the short tubes in the framework would be formed into an elliptical profile on the long axis of each tube (5) and assembled so that together they adopt the form of a helix (Figure 10).

Each support tube (5) is joined to its by mechanical means including but not exclusively overlapping tubular ferrules fitted internally or externally to the support tubes (5) each such mechanical connection being constructed of materials that are compatible with the structural support tubes (5). The connection between the ends of each such structural tube (5) in the helix would be coincident with an enclosing bearing plate (35) (Figure 6).

At the other end of the materials feed tubes (21, 22) there is fitted and secured a mechanically detachable machined driven ring gear (27) (Figure 9).

The drive gears (27) are manufactured in each case to be a precise fit with the toothed gearing (9 ID) exhibited on drive drums (91). The drive drums (91) are permanently connected to the rotary drive mechanisms (90) and also to a closure plate 91C that acts as a pressure door in this instance.

The rotary drive mechanisms (90) are arranged such that the inner rotating vessel (2) is rotated through 360 degrees by means of geared drive drums (91), mounted inside the doors (74, 84), The closure plates (91C 92C) are mounted on the drive drums (91) and connected to the drive drums (91) by mechanical means centred upon the sp lined drives (91 A ).

The circumference (29) of each closure plates (91C) is machined to form a precise fit with the outer face (28) of the drive gears (27) which is also carefully machined to provide a precise fit with closure plates (91C).

The geared drive drums (91) and closure plates (91C) are designed and made to engage with driven ring gears (27) and the machined face (28) respectively on the relevant materials feed tubes whenever the drive assemblies (105 106) are advanced into the "closed" position.

In order to facilitate loading and unloading of this particular embodiment of the present invention the rotary drive assemblies (105 106), which include the rotary drive mechanisms (90), the pressure doors (74 84), the drive drum assemblies (91) and closure plates (91C) may together be Opened or closed' as respects the openings (73 83) by virtue of being withdrawn from or moved towards the pressure vessel 1. Such movement is usually occasioned by mechanical means under computer control, such as, but not exclusively, by hydraulically operated or pneumatically operated pistons (77, 78) similar to those described in relation to the embodiment of Figure 1. As the assemblies (105, 106) are advanced to the "closed position", suitably along rails (79) as shown in Figure 12, the machined edges of the closure plates (91C) advance to meet and seal with the machined closure plate seat faces (28) of the driven gears units (27) just as the pressure doors (74, 84) (Figure 4) advance to meet and seal with the machined face (15B) of the relevant pressure tube (15) as the drive drums (91, 92) engage with the drive gears ends (27).

When in the 'closed' position the pressure doors (74 84) are securely clamped to the machined door seat (15B) by a plurality of clamps (23 A), that exert enough pressure on the pressure doors (73 and 84) to keep them sealed shut and sealed against the machined seat (15B) on the external pressure tube (15) irrespective of the difference in atmospheric pressure that develops in the inner space (24) as respected the ambient air pressure external to the pressure vessel (1).

The clamps (23 A) may be manipulated to open and close at appropriate times, usually but not exclusively, operated under either manual or computer by a plurality of hydraulically motivated pistons (23).

In this alternate embodiment of the present invention the fixed input hopper 78 is removed.

The loading and unloading tubes (71, 81) are also removed to be replaced by enlarged tubes (71A and 81A) (Figure 3) constructed of individual pressure resistant modules (IE) broadly matching the construction of those similar rings (IE) that form part of the main pressure vessel (1).

The enlarged loading and unloading tubes (71 A 81 A) are each adapted from the original rings (IE) by the creation of an orifice (71B, 81B) formed in the wall of the rings (IE) forming the larger loading tubes (71A 81AThe purpose of these orifices (71B, 81B) is to provide access to the external ends of the pressure orifices (73 and 83) found on the materials feed tubes (21 22), for attachment of the articulated external loading mechanism (78 A) and the corresponding unloading mechanisms to the pressure vessel (1) (in a secure manner after the relevant mobile assemblies (105, 106) are withdrawn away from the pressure vessel (1).

In the case of the loading tube 71 A at the upper end (70) of the pressure vessel (1) loading is enables by the provision of a new loading hopper 78A. The loading hopper 78A is a tube mounted upon a fulcrum (78B) suitably affixed to the upper edge of the loading tube 71 A. The loading tube (78A) is provided with an elbow (78C) at an end thereof (Figure 4). In Figure 3 the enlarged tubes 71 A and 81 A are shifted for clarity, but the correct arrangement of the enlarged tubes 71 A in relation to the loading hopper 78A is shown in Figure 11.

At the same end and beyond the elbow (78C) is provided clamp-able (plate 78D). This is associated with a nozzle (78E) which has the same external diameter as the internal diameter of the materials delivery tube (21) into which it locates periodically for the purpose of loading waste through the materials opening (73) of the materials delivery tube (21) into the space (24) within the inner rotating vessel (2).

On a side of the elbow (78C) there is provided a conduit (78F) that passes through the wall of the elbow (78D) at a point broadly coincident with the axis (61) of the nozzle (78E). This conduit is provided so that fluids, obtained from an external source, may pass through it into the materials delivery tube (78A) at a designed pressure for the purpose of promoting the efficient flow of waste input materials through the loading tube (78 A) into the inner rotating vessel (2). The conduit (78F) may be composed of a plurality of tubes each dedicated to a specific fluid.

As discussed above, the rotary drive mechanism may comprise a hydraulic motor or an electric motor or pneumatic motor or a combination thereof. However, care should be taken to ensure that any hydraulic motor utilised is not exposed to temperatures that would vaporise the fluids therein.

This may be achieved by mounting the rotary drive mechanism in a position away from the heated region of the pressure vessel (1), by fitting any hydraulic motors used to the outside face of the doors (74, 84) with, where necessary, a cooling system.

In that case, a central shaft (90A and 93 A) would be arranged to rotate the drive drum (91) (Figure 9) in a way contrived to ensure that the drive drums (91) engage with the geared drive head (27) secured to the materials feed tubes (21 and 22) at the exposed ends thereof. The rotary drive mechanisms (90) use an external source of energy such as but not exclusively electricity, pneumatics or hydraulics are used to replace the rotary drive mechanisms (11). These rotary drive mechanisms are secured to the outside of the doors (74,84).

The rotary power produced by the drive mechanisms (90) can be projected by mechanical means through the doors (74, 84) to a projected position that is substantially inside the body of the pressure vessel (1) such that it locates within, fills, seals and becomes secure within the relevant materials feed tubes (21, 22). The rotary drive mechanisms (90) apply rotational force by means of splined drives (90A). The splined drives (90A) form an integral part of the rotary drive mechanisms (90). They are usually formed as males drives.

The rotational forces delivered through the splined drives (90A and 93 A) are applied to the cylindrical drive drums (92, 91) through an orifice in the centre of the autoclave pressure doors (74, 84). Due to construction of the rotary drive mechanisms (90 93) and the way they are sealed to outer face of the pressure doors (74 84) there is no requirement for this orifice to be sealed in any other way.

The cylindrical drive drums (91) are each provided with a stout closed face (9 IB 92B) at an end thereof. This closed face (9 IB) of each drive drum (91 92) is capable of transmitting all rotational and other forces that are applied to the closed face (9 IB 92B) of each drive drum to the cylindrical periphery (9 ID) of the respective drive drums (91)

The positive connection of the hollow spline drives (91 A with the closed ends (9 IB), provides a means of transmitting rotary power to an array of toothed gears formed around the internal circumference (9 ID) of the drive drums (91) drums.

The hollow spline drives (91 A) also provide a mechanical means of connecting and securing the closure plates (91C) to both the pressure doors (74, 84) and the drive drums (91).

Between each of the drive drums (91) and the relevant closure plates (91C ) there is provided a substantial spring (9 IE) capable of applying a designed force. This spring holds the closure plates (91C) away from the drive drums (91) until the pressure doors

(74, 84) are fully closed and the drive drums (91) are forced towards the pressure plates

(91C) by the action of the closing mechanisms such as pistons (77, 87) as shown in the embodiment of Figure 1.

Simultaneously the materials feed tubes (21 22) are sealed shut by the advance of the sealed edges (29) of the closure plates (91C) closing against the machined ends (28) of the geared ends (27) fitted to each of the feed tubes (21, 22).

The application of the external source of energy is controlled such that rotation of the cylindrical drums (91) may be either clockwise or anticlockwise and be accelerated progressively to achieve the speeds required to effect the desired processing of the material.

Rotation of the inner rotatable vessel (2) continues at a plurality of predetermined speeds maintained by the rotary drive mechanisms (11 and/or 90) which shall each be under computer control. The speed of rotation of the inner rotatable vessel (2), is such that high 'G; forces are applied to any free water that has not been absorbed by the treated materials. Typically, but not exclusively, the maximum G force is measured at 50G.

The water that is 'spun' out of the treated mass as a result of the G forces created by the rotation, passes through the perforations in the inner wall (6) to be contained by the outer wall (4) of the inner vessel (2) and from there directed towards the lower savaran dish (19). The water thus accumulated is now drained off by means of a drainage pipe in the piped connection (31) through a computer-controlled valve (32).

The operation of the autoclaves of the invention will now be described.

In the embodiment illustrated in Figure 1 , the materials to be treated by autoclave are loaded into the feed hopper (78). The material falls under gravity into the input feed tube (71). It is contained within the feed tube (71) from where it enters the delivery scoop (69) before passing due to gravity though the opening (73) into the pressure vessel (1) by way of the materials feed tube (21). During this time the inner rotatable vessel (2) is turned by the rotary drive mechanism (11) such that the vanes (65) mounted within the inner rotatable vessel (2) impinge on the materials falling from the scoop and sweep them down the inner rotatable vessel (2) towards the lower materials feed tube (22).

In the alternate embodiment in which the fixed hopper 78 is replaced with an articulated hopper articulated (78A). Upon demand from the controlling computers the articulated hopper is pushed into an upright position by mechanical means such as, but not exclusively, a fluid operated ram or rotary actuator (78B) (Figure 4). The articulated hopper (78A) is then secured to the machined pressure seating (15B) at the opening (76) on the pressure tube (15) by the clamps (23) before the air relief vent (54) is opened to allow an external source of vacuum to be applied to the internal space (24) within the inner rotary vessel (2). The waste material is now fed into the open end of the articulated hopper (78A) and is encouraged to flow through the nozzle (78E) by the influence of the vacuum being applied through the space (24). The waste flow is further encouraged by the injection of fluid resources through the conduit 78F.

When the appropriate mass of material has been delivered into the pressure vessel (1) the doors (74, 84) are closed and locked to contain any pressure fluctuations within the pressure vessel (1). The inner rotatable vessel (2) is now rotated continuously for a designed time period generally but not exclusively within the range 1 to 3 hours. The rotation is executed at a plurality of rotational speeds normally within the range 10 to 60 revolutions per minute. As a result of this rotation, at least some liquid contained in the material will be forced through perforations in the inner wall (4) into the air space 5 A and will then run down towards savaran dish 19 and into the piped connection (31).

During the treatment period the ambient air pressure within the pressure vessel

(1) is reduced by the application of vacuum from an external source or by injecting and then condensing steam within the internal space (24) of the inner rotatable vessel (2). Condensing the steam is achieved by the application of cold water injected into the space (24) under pressure from an external source.

This event has the effect of opening sealed containers allowing the contents to be discharged within the inner rotatable vessel (2).

To achieve this effect steam, is injected into the pressure vessel (1) added directly into the inner rotatable vessel (2) from an external source such as, but not exclusively, an electrode steam boiler working in conjunction with a steam accumulator injecting steam through a piped network connecting with the inner space (24) within the inner rotating vessel (2) by means of a plurality of computer controlled valves (50 53) connected within the piped network.

Simultaneously air would be removed from the space (24) within the inner rotating vessel (2) by way of piped connection 19 leading to a plurality of attached valves (52 47) all under computer control.

When the space (24) within the inner rotating vessel (2) is full of steam a cold water spray (63) is activated and cold water is pumped into the inner rotating vessel (2). As a direct consequence, the steam is condensed and both the internal pressure and temperature within the space (24) within the rotating inner vessel (2) will adjust spontaneously to a predetermined level designed to effect the treatment desired.

The ambient pressure of the air gap (3) that lies between the outer wall (4) of the inner rotatable vessel (2) is automatically decreased to match any increasing vacuum created within the space (24) within the inner vessel (2) by means of a non-return valve positioned within the external piped network operating through the piped connection (40) which shall be connected by a piped network to the pipe network connection 41 through a non-return valve set in the piped connection between valve (45) and valve 50 respectively.

After a designed period of time fresh steam is introduced into the space 24 of the inner rotating vessel to raise the pressure in the inner space (24) to a typical operating pressure above 5 bar.

Simultaneously compressed air from an external source of adequate capacity is fed via a computer controlled valve (54) into the air gap (3) that lies between the outer wall (4) of the inner rotatable vessel (2) and the outer wall of the outer pressure vessel (1). The ambient gas pressure within the space (3) is thus raised to match the rising steam pressure within the inner rotatable vessel (2) in real time.

As part of the treatment of the materials, the pressure in the space (24) can be swiftly reduced by releasing steam from the inner rotatable vessel (2) by way of a piped network connection (41) which enters the savaran dish (17) at the elevated end (70) of the pressure vessel (1).

In a particular embodiment, the steam thus released is further transferred by means of the piped network to the second autoclave which is of the same design as specified for the present invention and so may be reused.

Eventually, as part of the treatment process, any remaining steam may be similarly condensed by the addition of a cold-water spray (63) fitted within the elevated savaran dish (17). This has the simultaneous effect of swiftly reducing the pressure and temperature within the inner rotatable vessel (2) and the remainder of the pressure vessel

(1) thereby further condensing any steam remaining within the space (24) within the rotatable inner vessel (2).

In order to counteract the sudden reduction in pressure within the inner rotatable vessel (2), the ambient pressure of the air gap (3) that lies between the outer wall (4) of the inner rotatable vessel (2) and the interior of the pressure vessel (1) is allowed to adjust automatically to match the loss of steam pressure within the inner rotatable vessel

(2) ·

Such venting may be achieved through an automatic computer controlled demand valve (54) or via a not return valve on a piped network external to the pressure vessel (1) that is directly linked between the gap (3) and the inner space (24) via computer controlled valves (45 46).

Use of an autoclave as described above allows for efficient treatment of materials in particular waste materials, with a concomitant reduction in water content of the product. Such product may therefore be more easily handled.

Claims

1. An autoclave comprising:

(i) an outer pressure vessel (1);

(ii) a rotatable inner vessel (2) substantially coaxially arranged within said outer pressure vessel and rotatable about the common axis, said inner vessel comprising an outer solid wall (4) and an inner perforated wall (6);

(iii) entry means (21) for delivering material into a space (24) defined within said inner perforated wall of the rotatable inner vessel (2) ;

(iv) exit means (22) for recovering solid material from the space (24) defined within said inner perforated wall of the rotatable inner vessel (2);

(v) means (31) for recovering liquid from a space between the outer solid wall and the inner perforated wall (6) of the rotatable inner vessel (2);

(vi) means (11, 105,106) for rotating the inner vessel (2); and

(vii) means for supplying gas under pressure to the outer pressure vessel (1) and the rotatable inner vessel (2).

2. An autoclave according to claim 1 further comprising (viii) means for producing a reduced pressure or vacuum within the rotatable inner vessel (2) and optionally also in the outer pressure vessel (1).

3. An autoclave according to claim 1 or claim 2 further comprising means (40) for balancing pressure within the outer pressure vessel and the rotatable inner vessel.

4. An autoclave according to any one of the preceding claims wherein one or more vanes (65) are provided within the inner perforated wall of the rotatable inner vessel to direct material delivered to the space (24) defined within said inner perforated wall of the rotatable inner vessel to the said exit means (22).

5. An autoclave according to claim 4 wherein the one or more vanes (65) are helically arranged within the space defined within said inner perforated wall.

6. An autoclave according to any one of the preceding claims wherein the inner surface of the outer pressure vessel (1 ) is covered with a layer of insulation (1 A).

7. An autoclave according to any one of the preceding claims wherein supporting jockey wheel assemblies (37) are provided in the outer pressure vessel and arranged to stabilise rotation of the inner vessel (2).

8. An autoclave according to any one of the preceding claims wherein the entry means comprises a scoop (69) that projects into the space defined (24) within said inner perforated wall.

9. An autoclave according to any one of the preceding claims further comprising a door (74) mounted upon a hydraulic ram (77) that is able to close the entry means (73 and 21).

10. An autoclave according to any one of the preceding claims further comprising a door (84) mounted upon a hydraulic ram (87) that is able to close the exit means (83 and

22).

11. An autoclave according to any one of the preceding claims wherein the means (11) for rotating the inner vessel (2) is able to rotate the vessel either clockwise or anticlockwise at predetermined speeds by the application of energy supplied from an external source to a rotary drive (11, 105, 106).

12. An autoclave according to any one of the preceding claims wherein an opening of the entry means and/or the exit means is enclosed within a pressure tube (15).

13. An autoclave according to claim 12 wherein the rotation means is contained within the pressure tube (15).

14. A method for autoclaving material, said method comprising introducing said material through the entry means of an autoclave according to any one of the preceding claims, heating the autoclave to the desired temperature and pressure using for instance air and/or steam, rotating said inner vessel at a sufficient speed to cause liquid within the material to pass through the perforated inner wall, recovering liquid from the space between the outer solid wall and perforated inner wall of the inner rotatable vessel and recovering solid material through the exit means.

15. A method according to claim 14 wherein pressure substantially equivalent to the air/steam pressure within the inner rotatable vessel is maintained within the outer pressure vessel.

16. A method according to claim 14 or claim 15, wherein during part of a process cycle the operational air pressure within the inner rotatable vessel is varied to drop to a negative pressure or to rise to a high pressure.

17. A method according to any one of claims 14 to 16 wherein the material treated is waste material.

18. A system comprising a plurality of autoclaves as defined in any one of claims 1 to 13.

19. An autoclave comprising a chamber in which autoclave conditions may be achieved, entry means to allow material to enter said chamber, exit means to allow autoclaved material to be recovered from said chamber, and a pressure tube enclosing an opening associated with the entry or exit means.