Title of Invention	IMPROVED CAN PROCESSING
Abstract	In a first aspect the invention comprises an apparatus for heat-treating products, comprising: a retort into which the products to be treated are receivable; heating means for heating the retort; coolant spray means for spraying a liquid coolant onto products received in the retort; and shielding means to substantially prevent coolant sprayed from the coolant spray means from impinging on the interior of the retort. In a further aspect the invention comprises a method of protecting a retort comprising a retort wall defining a volume into which products to be treated are receivable, heating means for heating the retort, and coolant spray means for spraying a liquid coolant onto products received in the retort against thermal shock, the method comprising mounting shielding apparatus within the retort to substantially prevent liquid coolant sprayed from the coolant spray means within the retort from impinging on the interior of the retort wall.

Title of Invention

IMPROVED CAN PROCESSING

Abstract

In a first aspect the invention comprises an apparatus for heat-treating products, comprising: a retort into which the products to be treated are receivable; heating means for heating the retort; coolant spray means for spraying a liquid coolant onto products received in the retort; and shielding means to substantially prevent coolant sprayed from the coolant spray means from impinging on the interior of the retort. In a further aspect the invention comprises a method of protecting a retort comprising a retort wall defining a volume into which products to be treated are receivable, heating means for heating the retort, and coolant spray means for spraying a liquid coolant onto products received in the retort against thermal shock, the method comprising mounting shielding apparatus within the retort to substantially prevent liquid coolant sprayed from the coolant spray means within the retort from impinging on the interior of the retort wall.

Full Text	IMPROVED CAN PROCESSING TECHNICAL FIELD The invenidon relates to apparatus for the heat-treatment of contair ers of predominantly liquid substances, fox example of foodstuffs, in a pressure vessel- BACKGROUND ART In a normal canning process a liquid or serniquid food product optionally containing solids, such as a soup, a cooking sauce, etc. is tilled into empty cans through an open, end to an appropriate level, leavir a headspace above the product, and the open end of the can is then hermetically sealed with an end closure. The cans and their content are then sterilised by heating, the heating medium used being usually e liher steam or hot water at a temperature of typically between 115aC and I30'G To achieve this temperature the steam or hot water has to be held at super-atmospheric pressure, and, accordingly the cans and the heatir g medium are contained in a pressure vessel known as a retort or cooker The cans, after filling and dosing, are placed in the retort, the retort dosed, and steam or water is introduced. Temperature controllers ar usually present on the retort to maintain the heating medium at the desired temperature. "While the cans axe in the retort, heat from thehrating medium is conducted through the container walls and thence passes into the product. AH parts of the food product in the can have to reach and hold suflicient temperature for a sufficient time to achieve so-called 'commercial: terility', A large number of products rely mainly on conduction rather than convection to distribute the heat through the can. Typically cans oi 73mxn diameter by 110mm long have to be held for a process time of 80 -70) minutes at 121'C, Once sterilised the can must then be cooled, usue lly with cold water, to a temperature of about 40'C before being removed from the retort with the cooling and removal procedure taking around 60 minutes. The total cycle time for placing the tin-sterilised, cans in the retort to removing them after sterilisation and cooling can be as long as three hours in conventional retorts. This leads to a maximum throughput of just two or three batches of cans for a given retort each working shift. In other words, the retort undergoes only two or three thermal cycles during each working shift. The long heating times indicated above can lead to overcooking of ti 2 food product especially where it lies adjacent to the container wall, be commercial practice it is already well known to reduce the heating Then of food products in a static retort by agitating the can, by rotating it within the retort. The rotation of the can has been affected either by rotating the can about its cylindrical axis, or by tumbling the can 'end-over-end' a bout a transverse (diametric) axis through its centre. The first form of agitation can be generated by rolling cans of circular section about their longitudinal axis and is widely used in 'Reel and Spiral' cookers. This method of agitation does not induce very effic rent mixing of the can's contents, and results in process times being red iced to about 50% as compared to heating without agitation, 'Bnd-over-enc 1' tumbling rotation induces better mixing and process time reductioi to about 35%, as compared to heating without agitation, can be expect >d. In PCT patent application WO 96/11592 there is described a method in which cylindrical cans are held with their axes horizontal, and are noved with a horizontal axial reciprocating motion during tiie heating and cooling stages, inducing peak accelerations of 1g or greater (g being the acceleration due to gravity). This process enables canned foodstuffs o be sterilised in typically tenths of the time taken using conventional heating methods, and thus a retort operated -using this process may experien tens of thermal cycles per day rather than just the customary two or three. Conventional retorts for heating cans are designed for a lifetime of to is of years, on the basis of thermal cycle times of three or more hours. If the methods of WO 96/11592 are used, then thermal cycle times are reduced to typically under one hour or possibly to less than 30 minutes and even down to 15 minutes. The necessarily rapid changes in temperature to achieve these short cycle times increase the thermal stress loadings on the retort. Such repeatec thermal loading of the retort can considerably shorten its service life, principally due to the high thermal shock expexienced when cooling water is sprayed onto the cans to cool them.. Such spray water can splash or otherwise be redirected onto the interior surface of the retort, causing sudden local cooling which generates internal stresses in the retot i: wall. These stresses can, after a relatively small number of repetitions, 1 -ad to the development of cracks, and even to structural failure of the retort DISCLOSURE OF INVENTION According to a first aspect of the present invention there is provided apparatus for heat-treating products, comprising: a retort into which the products to be treated are receivable, heating means for heating the retort; coolant spray means for spraying a liquid coolant onto prod ucts received in the retort; and shielding ineaxts to substantially prevent coolant sprayed frc m the coolant spray means from impinging on the interior of the retort. According to a first preferred version of the first aspect of the present invention the shielding means comprises one or more plates of solic metal or plastics sheet material. According to a second preferred version of the first aspect of the prt sent invention the plates of the shielding means comprises foam or mesh material having a pore or mesh size effective to prevent droplets or streams of coolant from impinging on the retort wall. According to a third preferred version of the first aspect of the present invention, or of any preceding preferred version thereof the shieldin means comprises an impervious layer of thermally insulating material According to a fourth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the shielding means includes a sump tray mounted at a lower region of the shielding and a drain conduit extending from the tray through the retort wall to drain liquid from the tray, and a plurality of vertically extending plates positioned with their lowermost edges above the sump tray so that liquid impinging on the plates will be collected in the sump tray. According to a fifth preferred version of the first aspect of the prese it invention or of any preceding preferred version thereof the retort further comprises agitating means for applying a reciprocating motion to products received in. the retort-According to a sixth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the shielding; means is fixed relative to the retort-According to a seventh preferred version of the first aspect of the present invention or of any preceding preferred version thereof there is provided a carrier for supporting products for processing within, and movable relative to, the retort, and at least one of the plates of the shielding means is mounted on the carrier. According to an eighth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the retort is further provided with trap means at a lower part of the retort adaptec to catch coolant liquid impinging on the retort wall due to failure of the shielding means, and a selectively openable drain valve in comminication, with the trap and openable to drain liquid from the trap. Typically the trap means incorporates a sensor for detecting the presence of liqiuid in the trap means such, as a level sensor or a sensor adapted to detect a constituent of a liquid coolant composition. According to a second aspect of the present invention shielding apparatus for a retort comprises a letort wall defining a volume into which products to be treated are receivable, heating means for heating the retort, and coolant spray means for spraying a liquid coolant onto products received in the retort, and shielding means mountabte within -the retort to substantially prevent liquid coolant sprayed from the coolant spray r Leans from impinging on the interior of the retort wall According to a first preferred version of the second aspect of the pres t invention the shielding means comprises one or more plates of solid heet material According to a second preferred version of the second aspect of the present invention the shielding means comprise foam or mesh material having a pore or mesh size effective to prevent droplets or streams of coolant from impinging on the retort wall. According to a third preferred version of the second aspect of the present mvention the. shielding means comprises an impervious layer of ther aally insulating material. According to a fourth preferred version of the second aspect of the present invention or of any preceding preferred version, thereof the shielding means includes a. sump fray mounted at a lower region of the retor and having a drain conduit extendable through the retort wall to drain liquid from the tray, and a plurality of vertically extending plates position able with their lowermost edges above the sump tray so that liquid imp; aging on the plates will be collected in the stamp tray. According to a, third aspect of the present invention there is provided a method of protecting a retort comprising a retort wall defining a volume into which products to be treated are receivable, heating means for 1 eating the retort, and coolant spray means for spraying a liquid coolantont products received in the retort against thermal shock, the method comprising the step of mounting shielding means within the retort to prevent liquid coolant sprayed from the coolant spray means within the retort from impinging on the interior of the retort wall. According to a first preferred version of the third aspect of the present invention the method includes the steps of: mo-unting a sump tray at a lower region of the retort; providing a drain conduit through the retort wall to drain liquid from the tray; and mounting a plurality of vertically extending shield plates with in the retort with the lowermost edges of the plates positioned above the sump tray. According to a second preferred version of the third aspect the me hod of the .first preferred version wherein the shielding means comprises : n impervious layer of thermally insulating material; includes the steps of; opening the drain valve to empty the trap; closing the drain valve prior to a cooling operation; and establishing shield failure by sensing liquid coolant in the tr p after the cooling operation has started. Typically the step of detecting liquid comprises either detecting a level of the liquid or detecting a constiduent of the liquid. According to a fourth aspect of the present invention there is proviced apparatus for locating within a retort a plurality of substantially cylindrical objects having a pair of transverse end. walls joined at thier edges to a side wall in paraxial layered relation with objects spaced \ y at least a minimum predetermined spacing distance from each other, comprising: a substantially planar mat having first and second faces and a plurality of arrays of projections extending from one of said faces, each array being arranged to receive an end face of one of said objects there-between in a location position; wherein the height of the projections ts so arranged that when one end face of an object contacts a free end of a projection, the other end face of the object is offset from its location position. According to a. first preferred version of the fourth aspect of the pres nt invention the height of the projections is so arranged that when one and face of an object contacts a free end of a projection, the other end fact of the object is offset from its location position by at least the minimi ft predetermined spacing distance. According to a. second preferred version of the fouith aspect of the present invention or of the first preferred version thereof each array compx MB three or more projections. According to a third preferred version of the fourth aspect of the pr sent invention or of any preceding preferred version thereof each projection comprises a cylindrical base section and a conical top portion. Typically the diameter of the base section corresponds to said minimum predetermined spacing distance, A main concern of the present invention is to provide means to improve the service life of a retort wherein cans are successively heated and particularly cooled, by spray-cooling, and wherein agitation of the c ns during heating and/or cooling leads to rapid thermal cycling of the etort. The present invention also seeks to provide a retort apparatus and a:. operating method for thermal treatment of earned products whereir the service life of the retort is maximised by reducing or eliminating . thermal shock to the retort. A further concern of the invention is to provide a. detection system : detecting impingement of coolant of the interior of the retort. Another aspect of the invention provides for a layer mat for placiring between the layers of cans in the retort to locate the cans and optically to assist in the control of the flow of coolant In the desaiption the term 'cylindrical' is not to be construed as the iting to products having a cross-section which is circular but to any substantially cross-section BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described in detail with reference to the accompanying drawings,, in which: Figuie 1 is a schematic sectional side view of a retort in. operation tc heat a plurality of cans; Figuie 2 is a transverse sectional view of the retort of Figure 1; Figure 3 is a schematic partial side view of a layer mat, showing potional of cans; and Figure 4 is a diagrammatic view of cans as loaded into a retort. MODES FOR CARRYING OUT THE INVISNTION Referring now to Figures 1 and 2, there is shown a retort installatior comprising a retort 2 and an agitator drive assembly 3. The retort comprises a cylindrical pressure vessel 4 having a closed nd 5 and an open 6 to which is mounted a door 7. The door 7 is supports by a hinge 8, seen at the top of the door in this embodiment, and is held closed by a locking screw 9. The door 7 may be opened by releasing the locading screw 9 and rotating the door clockwise (as seen in Figure 1). The door 7 may be supported at its side or lower edge instead of the top edge ,s shown, and may be locked closed by other means than the locking crew 9 shown in Figure 1, The door may have a domed shape (convex irwardly or outwardly) to better resist internal pressure within the pressure esse14 Extending axially within the pressure vessel 4 are mounted a pair o rails 11, on which a carriage or ca.ge 12 runs on wheels 13. The cage is ad pted to contain a plurality of cans 14 in horizontally-extending layers seprated from adjacent layers by layer mats 15. The layer mats 15 have vertic lly-extending locating studs 16 to engage the cans 14, as will be describ d in more detail later. The agitator drive assembly 3 comprises a flywheel 17 rota table by; motor (not show) and carrying a crank pin 18 to which one end of a connectJAg rod 19 is attached. The other end of title connecting rod 1! is attached to a crosshead 20 which is held between a pair of crosshead guides 21. As will be appreciated, rotation of the flywheel 17 will cat se reciprocating linear movement of the crosshead 20 to the left and rig t as seen in the Figure. The crosshead 20 is attached to one end of a drive rod 22, which pass is through a bearing seal 23 set in the dosed end wall 5 of the retort 2,the other end of the drive rod 22 is attached, preferably by a releasable coupling, to the cage 12, The drive rod extends parallel to the rails 11 so that rotational motion of the flywheel is converted into reciprocation movement of the cage 12 along rails 11. The frequency of the reciproction motion, and thus the acceleration experienced by ifhe cage and its o ntents, is variable by controlling the speed of the flywheel 17. theretort is provided with, an inlet port 24 for introducing a heatin; medium such as steam or heated water into the retort 2, and an in valve 25 controls the flow of the heating medium through the port 24 A c iifuser or spreader (not shown) may be provided to distribute the heating faid (steam or water) throughout the interior of the retort. Upper 26 and lower 27 outlet ports are provided in the retort wall, controlled by respective upper and lower outlet valves 28 and 29, A purging inlet port 30 is further provided, controlled by a purging valve 31. To cool the cans after they have been maintained at high temperature for sufficient lime, a coolant spray bar 32 extends along the upper part of the retort 2, with spray nozzles 33 for directing a coolant spray onto the and 14 in the cage 12, The flow of coolant is controlled by coolant valve 31, Multiple spray bars or other spray nozzle arrangements may be provided, so that a coolant flow Is delivered to all the cans in the batch being processed. The preferred sequence of operation of the retort of Figures 1 and 2 will now be described. Filled and sealed cans are loaded into the cage 12 and are clamped ir to position within the cage. The cage is them loaded into the retort with ts wheels 13 positioned on the rails 11 within the retort 2. The cage is then attached to the drive rod 22, which passes through the closed end of the retort, and the retort door 7 is dosed and locked in place. The drive motor to agitate the cans is then switched on causing the and and cage to reciprocate back and forth with a motion defined by tin speed of rotation, of the flywheel 17 and the throw of crank pin 18. The motion is transmitted to the cage via the connecting rod 19, crosshead 20 and Irive rod 22, The actual agitation conditions to be used will depend on such things as the viscosity of the food product and the fill level in the can, but should be of sufficient intensity to produce a maximum acceleration of at least Lg. Typical conditions could be a flywheel speed of 12orpm and a strok of 150mm, producing a peak acceleration equivalent to 1.4g. Once agitation at the correct intensity has started the heating process can commence. In the retort shown this is carried out using steam. For it is type of process steam is the preferred method of heating as it has a higher heat transfer coefficient than water. Steam will also easily contact all surfaces of the containers. It is difficult to achieve this level of contac with sprayed or raining water systems. Steam, or a steam/air mixture, from a pressurised supply (not showr is introduced into the retort via inlet port 24 by opening inlet valve 25. Upper 28 and lower 29 outlet valves are held open to allow air to escape from within the retort 2, in. an operation called venting. When the ret it reaches a temperature of approximately 100'C and quantities of stear are. issuing from upper and lower outlet ports 26 and 27, the lower otji et valve 29 is dosed and steam is allowed to issue from upper outlet ] ot 26 for a further predetermined period before the upper valve 28 is als closed. Venting schedules, i.e, the intervals between opening valve 25 and closing valves 28 and 29, are preferably determined experimentally for each retort. The retort now comes up to the required process temperature with he flow of steam -through the inlet valve 25 being controlled by a ccm.tr »1 circuit 34 responsive to a, temperature sensor 35 positioned within t' e retort 2, Once the required temperature in the retort is reached, the iming of the process starts. At the end of the predetermined process time, inlet valve 25 closes to stop the flow of steam into the retort 2, and air from purging inlet port 3{ is introduced via purging valve 31 to sweep steam from the retort, while maintaining the pressure at the levd used during the heating proceg This is controlled using pressure sensor PI, with steam being exhausted through the upper and/or lower outlet ports and valves. when enough steam has been swept from the retort and been replaced with air, cooling can commence by use of sprays of cooling water from nozzles 33 in spray bar 32 fed by water from valve 34 If too much st am is left in the retort when cooling starts the cold water will condense the steam and the pressure in the retort will drop excessively. As cooling proceeds the pressure in the retort is allowed to fall sloly back to atmospheric Once the cans are cooled, usually down to ab out 40"C, the retort is opened and the cans unloaded. Typically the total cycle time is about 15 minutes. It is possible to use the system for contair are other than metal cans, though because of their robustness and high thermal conductivity they are the preferred container. In. a retort thai uses steam fox heating and sprays of cold water for cooling, the major thermally induced stress will occur when, the steam contrcts cold areas of the retort during the heating phase, and when cold wa er contracts hot areas of the retort during cooling. Areas of particular concern are where there are welds and changes of section. It is, therefore, proposed that the retort pressure vessel be protected from large thermal shock loads firstly by shielding it from the cooling water and/or secondly by pre-heating it at the start of the day or at the start of each operational period. Its temperature will only fluctuate by a relaively small amount over the working period. Coolant shielding In the illustrated embodiment of Figures 1 and 2, the cooling water sprayed from nozzles 33 is prevented from contacting -the hot interns surfaces of the retort so that all areas; of the retort are maintained at a high temperature throughout the process cycle (say greater than 1006). Should plates 37 are arranged to extend longitudinally within the retort outs; be the path of the cage 12; the lower edges 37a of the shield plates 37 being arranged above a sump tray 38 which extends below the rails 11. The positioning and dimensions of the shield plates 37 are such that w. ter sprayed from the nozzles 33 which bounces from the cage 12 and c ins 14 impinges on the shield plates and runs down into the sump tray 31 The sump tray drains through a drain 39 controlled by a, drain valve 40 which is dosed while the retort is pressurised, preferably after the lower \ alve 29 in the venting stage, and opened to allow coolant to exit during the cooling phase of the cycle. Until the pressure within the retort has t sen sufficiently reduced, opening of the valve 40 will be controlled so a not to allow sudden depressurisation but to permit a sufficient rage of egress of coolant to prevent overflowing of the sump tray 38. One or more sensors may be provided in the sump tray, linked to the control cirecntry fox the drain valve 40, to increase opening of the drain valve 40 as tl e level of liquid in stunp tray 38 rises. The shield plates 37 may be mounted to the interior of the retort wa ,, preferably on thermally instilated mountings 41, as shown at -the rig it-hand side in Figure 2. Alternatively, the shield plates 37 may be irv-tirned, as seen in Figure 2, to ensure that water flowing from the plates 37 v ill fall into the sump tray 38. When the plates 37 are mounted on the cage cages) 12, then the sump tray must be dimensioned so that water flo wing OR dripping from the plates 37 falls into title tray 38 irrespective of the reciprocating motion of the cage 12 and plates 37, The shield plates 37 may be of solid metal or plastics sheet material, may be formed from foam or mesh materials, provided that they are of a pore or mesh size effective to prevent droplets or streams of coolant rom impinging on iihe retort wall. A mesh having openings of 1mm or less preferably 0.5mm or less, and most preferably 0.25mm or less, in ameter is effective as a shield against rebounding droplets. In an alternative arrangement, the shielding may be effected by ap] lying an impervious layer of thermally insulating material to the interior of the retort wall, to prevent contract between the coolant and the wall. It is also preferred to thermally isolate ihe pipes bringing in and car ying away cooling water from the body of the retort, by surrounding ihe Apes with thermal insulation at their points of passage through the retort There is a risk that during the cooling phase of the process cycle the shields provided to keep the cooling water from contacting the hot alls of the retort are not totally effective, and may allow cold water to flc onto the interior of the retort walls, cooling them locally at the point of contact. The present invention provides for monitoring means to det to failures of the shielding, as seen in detail in Figure 3. The monitoring means comprises, in the illustrated embodiment, a trap 43 formed by a tube 44 closed at its lower end 44a and fixed into the lowermost part )f the wall, 4 of the retort 2 to form a downWardly-extendirvg trap, open to t the interior of-the retort The retort 2 is arranged so that any coolant spra which strikes the interior of the retort will run down into ihe trap 43. Che trap 43 is provided with, a coolant sensor45, which may be a level sen or or a capadtive sensor, to detect coolant collected in the trap. The cool xvt sensor 45 may provide detection signals to the control circuit 34, or in tybe an independent unit providing audible or visual detection signals by sounding or display device. The trap 43 has a drain valve 46 for empting the trap prior to use, which may be controlled manually or by the c >ntrol circuit 34. Before each cooling cycle, the drain valve 46 is opened to dear the t ap 43 of any condensate, and is then re-dosed. If any coolant runs into fh At ihe start of the cycle, ie. with the retort 2 open ready to be loadec with. cans, the drain valve 46 on the trap 43 is opened to ensure the trap is empty. If it is not, the control circuit 34 will cause a warning to be given, and the process cycle will not be allowed to commence. Once the retort 2 is loaded, the door 7 closed and the steam, supply torned on by opening the inlet valve 25 to start the heating process, the drai valve 46 on the trap 43 closes. As the heating process proceeds consate v/ill run down, the wall 4 of the retort and start to fill the trap 43, and the rise in the level of liquid in tube 44 will be detected by the sensor 45, nd monitored by Hie control circuit 34. The signals from sensor 45 may be compared with signals from previous heating cycles by the control circuit 34, to ensure the readings are typicaL This can not only check that the level sensor is working, but may also serve to indicate that nothing untoword is happening during the heating phase if the sensor signals substantial correspond to those of earlier process cycles. If different results are obtained, e.g. if larger amounts of condensation from the steam supp y detected, this may indicate unusual heat losses from the retort that couald prejudice the process, or may indicate excessive amounts of liquid vater in the steam. At the end of the heating stage of the process cycle air is introducec tiirough purging valve 31 to sweep the steam from the retort and n :>lace it with air before cooling can begin. During this phase the dram valve 46 on the trap 43 is opened and the condensate drained away until the sex sox 45 detects the trap to be empty, whereupon the drain valve 46 is closec The cooling phase now begins During normal operation no coolant YI drain into the trap 43 and the sensor 45 will confirm this to be the ca e. If, however, the coolant is not all caught by the shields 37 and sump trt y 33, the trap 43 will start to fill and the coolant in trap 43 will be detected by the sensor 45, The control circuit 34 will then alert the operator to fhi abnormal situation, and may be programmed to allow the cooling pi ase to be completed but not allow the next cycle to commence without authorised interveatiotion As an alternative to detecting the level of liquid coolant in trap 43, th coolant may have an additive such as a dye or chemical tracer which nay be detected visually through a window in tube 44, or the sensor may be arranged to detect the tracer chemically by analysi9 of the trap ranter . For example, the coolant may include an additive which makes the p I of the coolant different from the usual condensate, and maybe detected by testing the pH of the trap contents with litmus. Condensate from the heating process will not contain the additive, and thus presence of flu additive in trap 43 will indicate shield failure without necessarily laving to drain the trap before each cooling cycle, la a preferred embodiment, the functions of the trap 43 and the lo\ -er outlet 27 may be combined, by providing a coolant sensor 45 at fh* outlet 27 upstream of the lower outlet valve 29, Downstream of the lowei outlet valve, a diverter arrangement will be provided to vent steam from he lower outlet valve to atmosphere, and to direct coolant either to a suitable drain., or to a refrigeration or heat exchanger circuit for cooling and recycling. In a water spray heating and cooling retort, the cans in the retort ar heated not by filling the retort with steam, but by spraying the cans with hot water. Cooling is effected by spraying with cold water as descri »ed above. By providing the shielding described above both for the hot .nd the cold water, the retort walls are at all stages isolated from contac with the hot and cold liquids, greatly reducmg the thermal cycling of the retort and extending its life, The shield failure sensor described above will be effective to detect hot as well as cold water impinging m the retort wall, Pre-heating The retort may additionally or alternatively be operated using a regine which minimises the thermal shock to the retort at the start of the precess cycle. This is particularly suitable to retorts heated by steam or stear/air mixtures, and is achieved by slowly pre-heating the retort prior to charging the retort with cages of cans. An example of such an operating regime would be as follows: With the retort empty of cans and cages the door is closed and the preheating step commences, in which the temperature of the retort is raised slowly to 100aC over a time that is dependent on the initial temperature of the structure of the retort by partially opening then let valve 25 to admit a limited flow of steam. The colder the retort, the onger is the pre-heating time, preferably up to a maximum of about 5 min ites. The exact time required to preheat any particular retort form an inital temperature to its operating temperature will preferably be determined by experiment. As the initial temperature of "the retort may not be known precisely, it may be estimated from the length of time since the end if the last process cycle together with a knowledge of the cooling rate of the structure. From this estimate the required length of pre-heat can be determined. When the retort reaches 1006C the steam supply is then turned fully (inlet valve 25 fully open) to correctly vent the retort for, say, ten sea ads before the Lower outlet poxt 27 is closed followed by a further ten seconds, say, before the upper outlet port 26 is closed. The steam supply is immediately reduced, by partially closing the inlet valve 25, to a leve such that it will take the retort a further two minutes or so to reach process temperature and pressure. (For a given installation the required inter al us conveniently determined by experiment). The process foxier is now started and foe process continues for as long as experiments have determined to be necessary to raise the fabric of the retort substantially to Its working temperature. The steam supply (inlet vale 25) is then turned off and the upper or (let port 26 opened slowly to allow the steam to escape from, the retortnd reduce the pressure to zero. The pre-heated retort is ready for loading with one or more cages for cans for production. The slow pre-heating of the retort is done to avoid ihermal shocks curing this operation and as the retort is hot when production commences, thermal shock loads are significantly reduced. Control of the valves 5, 28, 29,31,34 and 40 is preferably affected by the control circuit 34, which may be a process controller, a programmable microprocessor or a person computer or the like. To ensure that the retort is always at a sufficiently high temperature :o avoid these shock loads the time from the end of the previous proce: 3 is measured. If it is too long the control circuitry 34 controlling the while operation of the retort is preferably arranged so as not allow the nex process cycle to commence until the retort is again pre-heated. The exact length of the pre-heating required varies, depending on the time tha has lapsed since the end of ih,e last process and other factors such as amlient temperature. The actual length of the pre-heat required is determine by experiment, and preheating times for various intervals since last use nay be stored in memory accessible to the control circuit 34 The control circuit 34 may be arranged to cause an audible or visual warning to be given before the end of the time interval after a heattn ; cycle in which a further heating cycle may be started without pre-he ting the retort, so that the operator can decide whether there is time to load the retort and start the next process or whether he needs to carry out s preheat cycle. Can Loading and Positioning, To achieve consistent process results, each container or can 14 must be held securely and in its correct position with respect to its neighbours. A method and apparatus for stacking cans 14 into their cages 12 is row described with reference to Figure 4, and is applicable to hand loaded semi-automatic or fully automated processing installations. The cage 12 is loaded with cans 14 by placing a layer mat 15 in, a horizontal position in the cage, with its studs 16 extending upwardh There is provided for each can in a layer, an array of studs arranged round the perimeter of a circle whose diameter corresponds to that of a can 14, at preferably equiangular but possibly irregular spacing. Most preferat y four studs are provided for each carv but in alternative embodiments iircee or fewer, or five or more, studs may be used. For cans of non-circtala] section, an. array of studs arranged to suit title cross-section of the can is provided. The uppermost and lowermost layer mats 15 are preferably provided with studs on one face only, while intermediate layer mats, intended to be positioned between two layers of cans 16, have studs on both faces. In the example shown each can 14 is located within the cage 12 by eig it cone shaped studs 16, four studs being attached to each of two layer I LATS 15 to locate respective ends of the can 14 The studs 16 have a cylir drical base section 16a and a conical tapered top section 16b ending in a as rounded tip 16c, The spacing of the studs is arranged to receive a particular and closely between each set of four studs. The minimum separation djtance S between adjacent cans 14 in a layer is, in the embodiment shown, equal to the diameter of the base section 16a of a stud 16, since the studs are arranged in ranks and files aligned with the ranks and file, of cans: 1 a layer, Alternative arrangements where studs are positioned so that each stud contacts three or four, rather than two, cans 14 are possible, using staggered rows of cans in each layer. The size and shape of the stud ; 16 is such that during ihe operation of loading cans into ihe cage, the corcal top sections 16b act as lead-in surfaces, and the cans are positioned accurately by contracting the base sections 16a of the studs 16. The cans 14 are loaded by placing ihe end of the can between the studs 16, If the and edge of the can contacts the conical top section 16b of a stud, the car will, be guided to its correct position. If a can is placed with the rounded ip 16c of a stud contacting the end of the can, as seen in chain lines in Figu 5 4, then the can will preferably be sufficiently misaligned as to interfere with at least on of its neighbours, and miss-loading will be apparent to ax operator. If this situation is not corrected it may also prevent fhe correct positioning of the next lay mat 15, making miss loading apparent. the present system is, however, tolerant of missing cans. Indeed this is a significant feature as it is almost certain to happen in practice. During loading the cans are arranged with, their axes vertical and with the layer mats 15 horizontal For loading into the retort 2, the cage 12 may be laid on its side so that, in. contrast to the example shown, the axes of the cans 14 are horizontal and parallel to the cylindrical axis of the retor i.,e the axes of the cans extend in the direction of their reciprocating movement during agitation. The cans 14 are preferably arranged in 'sticks' of axially aligned cans, with a gap between each two adjacent cans in the stick formed by file laer mat The layer mat may have an embossment or step on which each study 16 sits. In the preferred arrangement, the 'sticks' of cans extends horiz mtally in the retort, in the agitation direction, A clearance of about 10mm, >r possibly more, is provided between each stick of cans and its neigh out in the horizontal direction, sufficient to allow free flow of heating and ooling fluids. In the vertical direction each stick is preferably positioned di ectiy over the one beneath with a clearance space of about 3mm, or more between sticks. Such an arrangement gives good flows of both steal and water over the cans, though other arrangements may be satisfactory It should be noted with respect to the loading and location of the cans that cans may be cylindrical, so that the outside diameter of the two ends of the can are substantially equal, or the diameters of the ends of the can may differ by an amount of 2xnrn or more. To locate cylindrical cans, or cans whose end diameters differ by about 2mm or less, the same layout and spacing of studs is preferably used for both ends of each can. Most preferably, studs on opposite faces of the layer mat will be coaxial, with the stud layout adopted being that fox the larger of the two diameters if different. If the difference in diameter is great r than about 2mm, the spacing and/or layout of the studs may be varid as appropriate for each can end. Necessitating that the cans be loaded it a predetermined orientation. If this is not done correctly it will be d ar to the loader either at this stage or when the next layer mat is positio .ed. The cage may be loaded either by hand or by using a semi or fully automated system. The description below is for an entirely hand k ded operation-First the cage 12 is positioned with an open side upward, and a bat om layer mat 15 is placed in position to form a base, with the studs 16 projecting upwards, The first layer of cans 14 axe then loaded by standing each can 14 oi the layer mat 15 with the end of the can positioned by an array of studs 16 on the layer mat, each stud engaging the edge of the can. When a first] yer is completed, an intermediate type layer mat, having both upwardly extending and downwardly extending studs 16, is lowered vertical through the open side of the cage 12 to rest in a horizontal plane on he tops of tiie cans of the first layer. The layer mat may guided in the horizontal plane by the corners of the cage 12 so that the downward y extending studs 16 easily engage the edges of the cans, ensuring secore location of each The second layer of cans is then loaded in a manner similar to the first and another intermediate type layer mat lowered into position. The proc dure is repeated until ttve cage is full, when the top layer mat, 5, being of the same type as the bottom mat 3 but with its studs extending downwads, is added. A rdeasable clamping arrangement can then be used to se ure the layers of cans and their interposed layer mates 15 in position in fti cagel2. The loaded cage 12 is then positioned in the correct orientation on trolley ready to be loaded into the retort. The cage is preferably loaded in other retort with the layer mats in vertical planes, holding the cans 14 with. their axes horizontal and aligned with the reciprocation movement direc ion of the cage, when the cans have, an axial length equal to at greater tha their diameter (or a representative transverse dimension or 'width in the case where the cans are of non-circular cross-section). However, if the cans are of a squat shape where the axial height is less than their diameter 0,1 'width', a more effective orientation may be to keep the cans with their axes vertical or substantially vertical. For non-circular section containers, similar considerations apply the if the containers are squat in height and rectangular in cross-section they are preferably oriented with the reciprocation, direction aligned with flu longest transverse dimension. It should also be noted that for squat containers, whether reciprocate i in a direction parallel to thheir ends or at right angLes to them, layer mate 5 with studs 16 on just one side may be used not only at the top and be torn, but also as intermediate layer mates for locating the containers. The method of hand loading described is necessarily limited to cages of a depth, sufficiently shallow that the bottom layer can be reached. For deeper cages a semiautomatic system needs to be employed. For example, the cage may be placed on a suitable frame over a jacking arrangement that lifts up the bottom layer mat to a position near the open top of the cage, allowing for easy loading of the cans. Once the firs layer of cans is loaded, the jack is operated to lower this layer of cans by mat is amount equivalent to the height of the layer. An intermediate layer mat is then added followed by the next layer of cans. the procedure is rejeated until the bottom layer mat is positioned at the bottom of the cage, whereupon the top layer mat is placed over the uppermost layer of cans A clamp may then be used to lock the cans and mats in place. Such cage loading arrangements using jacking mechanisms of this t 'pe are conventional in the catuning industry, and can be used to load any size of cage. A fully automatic version could be envisaged using similar prindpl s, but instead of hand loading the cans into each layer an automated 'pick ind place' unit would be INDUSTRIAL APPLICABILITY The invention is applicable throughout the canning industry which 5 an industry of major importance in a large number of countries. Apartom providing for more rapid sterilisation of a given load of filled cans and so a greater throughput in a given time period) it reduces by a substanal amount the heat required in the step and so the fuel cost. CLAIMS 1 Apparatus for heat-treating products, comprising: a retort b to wfruch the products to be treated ate receivable; heating m&t is for heating the retort; coolant spray mear\s for spraying a liquid coolant onto products received in the retort; and, shielding means to substantially prevent coolant sprayed from the coolant spra^ means from impinging on the interior of the retort. 2 Apparatus as claimed in Claim 1 wherein the shielding mear comprises one or more plates of solid metal or plastics sheet material. 3 Apparatus as claimed in Claim 1 wherein the shielding mean comprises foam or mesh material having a. pore or mesh size effective to prevent droplets or streams of coolant from impir 5ing on the retort wall 4 Apparatus as claimed in any preceding claim wherein the shi Iding means comprises an impervious layer of thermally insulating material, 5 Apparatus as claimed in any preceding claim wherein the shit ding means includes a sump tray mounted at a lower region of the etart and having a drain conduit extending through ihe retort wall o drain liquid from the tray, and a plurality of vertically extendi xg plates positioned with their lowermost edges above fee sump ray so that liquid impinging 011 the plates v/ill be collected in tb • sump tray, 6 Apparatus as claimed in any preceding claim wherein the tetort incorporates agitating means for applying a reciprocating mation to products received in the retort 7 Apparatus as claimed in any preceding claim wherein the shuelding means is fixed relative to the retort 8 Apparatus as claimed in any preceding claim wherein the tetort incorporates a carrier for supporting products within, the tetort and movable relative to the retort, and wherein at least one of the plates of the shielding means is mounted on the carrier. 9 Apparatus as claimed in any preceding claim wherein the tetort is provided with trap means at a lower part of the tetort adapter to catch coolant liquid impinging on the retort wall due to faild 2 of ihe shielding means, and a selectively openable drain valve is coiranionication with tive trap and openable to drain liquid fro in the trap. 10 Apparatus as claimed in Claim 9 wherein the trap means Incorporates a sensor for detecting the presence of liquid in tti \ trap means such as a level sensor or a sensor adapted to detect a constituent of a liquid coolant composition. 11 Shielding apparatus for a retort comprises a retort wall defi ring a volume into which products to be treated are receivable, he ting means for heating the retort, and coolant spray means for sj raying aliquid coolant onto products received in the retort, and shielding means moutitable within the retort to substantially prevent" quid coolant sprayed from mountable coolant spray means from impinging on {he interior of tlie retort wall. 12 Shielding apparatus as claimed in Claim 11 wherein, the hielding means comprises one or more plates of solid sheet material. 13 Shielding apparatus as claimed in Claim 11 wherein the shie] ling means comprise foam or mesh material having a pore or met size effective to prevent droplets or streams of coolant from impringing on the retort wall. 14 Shielding apparatus as claimed in Claim 11 wherein the shielding means comprises an impervious layer of thermally insulating material 15 Shielding apparatus as claimed in Claims 11 to 14 wherein -the shielding means includes a sump toy mounted at a lower reg on of the retort and having a drain conduit extendable through the etort wall to drain liquid from the tray, and a plurality of vertically extending plates positionable with their lowermost edges above the sump tray so that liquid impinging on the plates will be collec ed in the sump tray. 16 A method of protecting a retort comprising a retort wall d fining a volume into which products to be treated are receivable, h atitig means for heating the retort, and coolant spray means for 5 graying a liquid coolant onto products received in the retort agajns thermal shock, the method comprising the step of mounting shieldi ig means within the retort to prevent liquid coolant sprayed from the coolant spray means within the retort from impinging on the interior of the retort wall 17 A method of protecting; a retort as claimed in Qaim. 16 inch iing the steps of: mounting a sump tray at a lower region of the retort providing a drain conduit through the retort wall to !rain liquid from the tray; and mounting a plurality of vertically extending shield p] ites within the retort with, the lowermost edges of the plates posi ioned above the sump tray, 18 A method of protecting a retort as claimed in Qaim. 16 when in the shielding means comprises an impervious layer of thermally insulating material; includes the steps of: opening the drain valve to empty the trap; closing the drain valve prior to a. cooling operation; and establishing shield failure by sensing liquid coolant in the trap after the cooling operation has started, 19 A method of protecting a retort as claimed in Claim 18 whe eiti the step of detecting liquid in the trap comprises either detectir * a level of the liquid therein or detecting a constituent of liquid the* an. 20 Apparatus for locating within a retort a plurality of substan ally cylindrical, objects having a pair of transverse end walls join d at their edges to a sidewaU in paraxial layered relation with ob sets spaced by at least a minimum predetermined spacing distan e from each, other, comprising; a substantially planar mat having fir t and second faces; and a plurality of arrays of projections extendi g from one of said faces, each array being arranged to receive an enc face of one of said objects there-between in. a location position; wlerein the height of the projections is so arranged that when one eru face of an object contacts a free end of a projection/ the other end ice of the object is offset from its location position. 21 Apparatus as claimed in. daim 20 wherein, the height of the projections is so arranged that when one end face of an object contacts a free end of a projection, live other end face of the ot ect is offset from its location position by at least the miniaimum predetermined spacing distance. Apparatus as claimed in Claim 20 or 21 wherein each array comprises three or more projections. 23 Apparatus as claimed in claims 20 - 22 wherein each projection comprises a cylindrical base section and a conical top portion. 24 Apparatus as claimed in Claim. 23 where in the diameter of flu base section corresponds to said minimum predetermined spacing distance, Dated this 28 day of August 2006

Full Text

IMPROVED CAN PROCESSING
TECHNICAL FIELD
The invenidon relates to apparatus for the heat-treatment of contair ers of predominantly liquid substances, fox example of foodstuffs, in a pressure vessel-
BACKGROUND ART
In a normal canning process a liquid or serniquid food product optionally containing solids, such as a soup, a cooking sauce, etc. is tilled into empty cans through an open, end to an appropriate level, leavir a headspace above the product, and the open end of the can is then hermetically sealed with an end closure. The cans and their content are then sterilised by heating, the heating medium used being usually e liher steam or hot water at a temperature of typically between 115aC and I30'G To achieve this temperature the steam or hot water has to be held at super-atmospheric pressure, and, accordingly the cans and the heatir g medium are contained in a pressure vessel known as a retort or cooker
The cans, after filling and dosing, are placed in the retort, the retort dosed, and steam or water is introduced. Temperature controllers ar usually present on the retort to maintain the heating medium at the desired temperature. "While the cans axe in the retort, heat from thehrating medium is conducted through the container walls and thence passes into the product.

AH parts of the food product in the can have to reach and hold suflicient temperature for a sufficient time to achieve so-called 'commercial: terility', A large number of products rely mainly on conduction rather than convection to distribute the heat through the can. Typically cans oi 73mxn diameter by 110mm long have to be held for a process time of 80 -70) minutes at 121'C, Once sterilised the can must then be cooled, usue lly with cold water, to a temperature of about 40'C before being removed from the retort with the cooling and removal procedure taking around 60 minutes.
The total cycle time for placing the tin-sterilised, cans in the retort to removing them after sterilisation and cooling can be as long as three hours in conventional retorts. This leads to a maximum throughput of just two or three batches of cans for a given retort each working shift. In other words, the retort undergoes only two or three thermal cycles during each working shift.
The long heating times indicated above can lead to overcooking of ti 2 food product especially where it lies adjacent to the container wall, be commercial practice it is already well known to reduce the heating Then of food products in a static retort by agitating the can, by rotating it within the retort. The rotation of the can has been affected either by rotating the can about its cylindrical axis, or by tumbling the can 'end-over-end' a bout a transverse (diametric) axis through its centre.
The first form of agitation can be generated by rolling cans of circular section about their longitudinal axis and is widely used in 'Reel and

Spiral' cookers. This method of agitation does not induce very effic rent mixing of the can's contents, and results in process times being red iced to about 50% as compared to heating without agitation, 'Bnd-over-enc 1' tumbling rotation induces better mixing and process time reductioi to about 35%, as compared to heating without agitation, can be expect >d.
In PCT patent application WO 96/11592 there is described a method in which cylindrical cans are held with their axes horizontal, and are noved with a horizontal axial reciprocating motion during tiie heating and cooling stages, inducing peak accelerations of 1g or greater (g being the acceleration due to gravity). This process enables canned foodstuffs o be sterilised in typically tenths of the time taken using conventional heating methods, and thus a retort operated -using this process may experien tens of thermal cycles per day rather than just the customary two or three.
Conventional retorts for heating cans are designed for a lifetime of to is of years, on the basis of thermal cycle times of three or more hours. If the methods of WO 96/11592 are used, then thermal cycle times are reduced to typically under one hour or possibly to less than 30 minutes and even down to 15 minutes.
The necessarily rapid changes in temperature to achieve these short cycle times increase the thermal stress loadings on the retort. Such repeatec thermal loading of the retort can considerably shorten its service life, principally due to the high thermal shock expexienced when cooling water is sprayed onto the cans to cool them.. Such spray water can splash or otherwise be redirected onto the interior surface of the retort, causing

sudden local cooling which generates internal stresses in the retot i: wall. These stresses can, after a relatively small number of repetitions, 1 -ad to the development of cracks, and even to structural failure of the retort
DISCLOSURE OF INVENTION
According to a first aspect of the present invention there is provided apparatus for heat-treating products, comprising:
a retort into which the products to be treated are receivable,
heating means for heating the retort;
coolant spray means for spraying a liquid coolant onto prod ucts received in the retort; and
shielding ineaxts to substantially prevent coolant sprayed frc m the coolant spray means from impinging on the interior of the retort.
According to a first preferred version of the first aspect of the present invention the shielding means comprises one or more plates of solic
metal or plastics sheet material.
According to a second preferred version of the first aspect of the prt sent invention the plates of the shielding means comprises foam or mesh material having a pore or mesh size effective to prevent droplets or streams of coolant from impinging on the retort wall.
According to a third preferred version of the first aspect of the present invention, or of any preceding preferred version thereof the shieldin
means comprises an impervious layer of thermally insulating material

According to a fourth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the shielding means includes a sump tray mounted at a lower region of the shielding and a drain conduit extending from the tray through the retort wall to drain liquid from the tray, and a plurality of vertically extending plates positioned with their lowermost edges above the sump tray so that liquid impinging on the plates will be collected in the sump tray.
According to a fifth preferred version of the first aspect of the prese it invention or of any preceding preferred version thereof the retort further comprises agitating means for applying a reciprocating motion to products received in. the retort-According to a sixth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the shielding; means is fixed relative to the retort-According to a seventh preferred version of the first aspect of the present invention or of any preceding preferred version thereof there is provided a carrier for supporting products for processing within, and movable relative to, the retort, and at least one of the plates of the shielding means is mounted on the carrier.
According to an eighth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the retort is further provided with trap means at a lower part of the retort adaptec to catch coolant liquid impinging on the retort wall due to failure of the

shielding means, and a selectively openable drain valve in comminication, with the trap and openable to drain liquid from the trap.
Typically the trap means incorporates a sensor for detecting the presence of liqiuid in the trap means such, as a level sensor or a sensor adapted to detect a constituent of a liquid coolant composition.
According to a second aspect of the present invention shielding apparatus for a retort comprises a letort wall defining a volume into which products to be treated are receivable, heating means for heating the retort, and coolant spray means for spraying a liquid coolant onto products received in the retort, and shielding means mountabte within -the retort to substantially prevent liquid coolant sprayed from the coolant spray r Leans from impinging on the interior of the retort wall
According to a first preferred version of the second aspect of the pres t invention the shielding means comprises one or more plates of solid heet
material
According to a second preferred version of the second aspect of the present invention the shielding means comprise foam or mesh material having a pore or mesh size effective to prevent droplets or streams of coolant from impinging on the retort wall.
According to a third preferred version of the second aspect of the present mvention the. shielding means comprises an impervious layer of ther aally insulating material.

According to a fourth preferred version of the second aspect of the present invention or of any preceding preferred version, thereof the shielding means includes a. sump fray mounted at a lower region of the retor and having a drain conduit extendable through the retort wall to drain liquid from the tray, and a plurality of vertically extending plates position able with their lowermost edges above the sump tray so that liquid imp; aging on the plates will be collected in the stamp tray.
According to a, third aspect of the present invention there is provided a method of protecting a retort comprising a retort wall defining a volume into which products to be treated are receivable, heating means for 1 eating the retort, and coolant spray means for spraying a liquid coolantont products received in the retort against thermal shock, the method comprising the step of mounting shielding means within the retort to prevent liquid coolant sprayed from the coolant spray means within the retort from impinging on the interior of the retort wall.
According to a first preferred version of the third aspect of the present invention the method includes the steps of:
mo-unting a sump tray at a lower region of the retort;
providing a drain conduit through the retort wall to drain liquid from the tray; and
mounting a plurality of vertically extending shield plates with in the retort with the lowermost edges of the plates positioned above the sump tray.

According to a second preferred version of the third aspect the me hod of the .first preferred version wherein the shielding means comprises : n impervious layer of thermally insulating material; includes the steps of; opening the drain valve to empty the trap; closing the drain valve prior to a cooling operation; and establishing shield failure by sensing liquid coolant in the tr p after the cooling operation has started. Typically the step of detecting liquid comprises either detecting a level of the liquid or detecting a constiduent of the liquid.
According to a fourth aspect of the present invention there is proviced apparatus for locating within a retort a plurality of substantially cylindrical objects having a pair of transverse end. walls joined at thier edges to a side wall in paraxial layered relation with objects spaced \ y at least a minimum predetermined spacing distance from each other, comprising: a substantially planar mat having first and second faces and a plurality of arrays of projections extending from one of said faces, each array being arranged to receive an end face of one of said objects there-between in a location position; wherein the height of the projections ts so arranged that when one end face of an object contacts a free end of a projection, the other end face of the object is offset from its location position.
According to a. first preferred version of the fourth aspect of the pres nt invention the height of the projections is so arranged that when one and face of an object contacts a free end of a projection, the other end fact of

the object is offset from its location position by at least the minimi ft predetermined spacing distance.
According to a. second preferred version of the fouith aspect of the present invention or of the first preferred version thereof each array compx MB three or more projections.
According to a third preferred version of the fourth aspect of the pr sent invention or of any preceding preferred version thereof each projection comprises a cylindrical base section and a conical top portion. Typically the diameter of the base section corresponds to said minimum predetermined spacing distance,
A main concern of the present invention is to provide means to improve the service life of a retort wherein cans are successively heated and particularly cooled, by spray-cooling, and wherein agitation of the c ns during heating and/or cooling leads to rapid thermal cycling of the etort.
The present invention also seeks to provide a retort apparatus and a:. operating method for thermal treatment of earned products whereir the service life of the retort is maximised by reducing or eliminating . thermal shock to the retort.
A further concern of the invention is to provide a. detection system : detecting impingement of coolant of the interior of the retort.

Another aspect of the invention provides for a layer mat for placiring between the layers of cans in the retort to locate the cans and optically to assist in the control of the flow of coolant
In the desaiption the term 'cylindrical' is not to be construed as the iting to products having a cross-section which is circular but to any substantially cross-section
BRIEF DESCRIPTION OF DRAWINGS
Embodiments of the invention will now be described in detail with
reference to the accompanying drawings,, in which:
Figuie 1 is a schematic sectional side view of a retort in. operation tc heat a
plurality of cans;
Figuie 2 is a transverse sectional view of the retort of Figure 1;
Figure 3 is a schematic partial side view of a layer mat, showing potional
of cans; and
Figure 4 is a diagrammatic view of cans as loaded into a retort.
MODES FOR CARRYING OUT THE INVISNTION
Referring now to Figures 1 and 2, there is shown a retort installatior comprising a retort 2 and an agitator drive assembly 3.
The retort comprises a cylindrical pressure vessel 4 having a closed nd 5 and an open 6 to which is mounted a door 7. The door 7 is supports by a hinge 8, seen at the top of the door in this embodiment, and is held closed by a locking screw 9. The door 7 may be opened by releasing the locading screw 9 and rotating the door clockwise (as seen in Figure 1). The door 7

may be supported at its side or lower edge instead of the top edge ,s shown, and may be locked closed by other means than the locking crew 9 shown in Figure 1, The door may have a domed shape (convex irwardly or outwardly) to better resist internal pressure within the pressure esse14
Extending axially within the pressure vessel 4 are mounted a pair o rails 11, on which a carriage or ca.ge 12 runs on wheels 13. The cage is ad pted to contain a plurality of cans 14 in horizontally-extending layers seprated from adjacent layers by layer mats 15. The layer mats 15 have vertic lly-extending locating studs 16 to engage the cans 14, as will be describ d in more detail later.
The agitator drive assembly 3 comprises a flywheel 17 rota table by; motor (not show) and carrying a crank pin 18 to which one end of a connectJAg rod 19 is attached. The other end of title connecting rod 1! is attached to a crosshead 20 which is held between a pair of crosshead guides 21. As will be appreciated, rotation of the flywheel 17 will cat se reciprocating linear movement of the crosshead 20 to the left and rig t as seen in the Figure.
The crosshead 20 is attached to one end of a drive rod 22, which pass is through a bearing seal 23 set in the dosed end wall 5 of the retort 2,the other end of the drive rod 22 is attached, preferably by a releasable coupling, to the cage 12, The drive rod extends parallel to the rails 11 so that rotational motion of the flywheel is converted into reciprocation movement of the cage 12 along rails 11. The frequency of the reciproction

motion, and thus the acceleration experienced by ifhe cage and its o ntents, is variable by controlling the speed of the flywheel 17.
theretort is provided with, an inlet port 24 for introducing a heatin; medium such as steam or heated water into the retort 2, and an in valve 25 controls the flow of the heating medium through the port 24 A c iifuser or spreader (not shown) may be provided to distribute the heating faid (steam or water) throughout the interior of the retort.
Upper 26 and lower 27 outlet ports are provided in the retort wall, controlled by respective upper and lower outlet valves 28 and 29, A purging inlet port 30 is further provided, controlled by a purging valve 31.
To cool the cans after they have been maintained at high temperature for sufficient lime, a coolant spray bar 32 extends along the upper part of the retort 2, with spray nozzles 33 for directing a coolant spray onto the and 14 in the cage 12, The flow of coolant is controlled by coolant valve 31, Multiple spray bars or other spray nozzle arrangements may be provided, so that a coolant flow Is delivered to all the cans in the batch being processed.
The preferred sequence of operation of the retort of Figures 1 and 2 will now be described.
Filled and sealed cans are loaded into the cage 12 and are clamped ir to position within the cage. The cage is them loaded into the retort with ts wheels 13 positioned on the rails 11 within the retort 2. The cage is then

attached to the drive rod 22, which passes through the closed end of the retort, and the retort door 7 is dosed and locked in place.
The drive motor to agitate the cans is then switched on causing the and and cage to reciprocate back and forth with a motion defined by tin speed of rotation, of the flywheel 17 and the throw of crank pin 18. The motion is transmitted to the cage via the connecting rod 19, crosshead 20 and Irive rod 22,
The actual agitation conditions to be used will depend on such things as the viscosity of the food product and the fill level in the can, but should be of sufficient intensity to produce a maximum acceleration of at least Lg. Typical conditions could be a flywheel speed of 12orpm and a strok of 150mm, producing a peak acceleration equivalent to 1.4g.
Once agitation at the correct intensity has started the heating process can commence. In the retort shown this is carried out using steam. For it is type of process steam is the preferred method of heating as it has a higher heat transfer coefficient than water. Steam will also easily contact all surfaces of the containers. It is difficult to achieve this level of contac with sprayed or raining water systems.
Steam, or a steam/air mixture, from a pressurised supply (not showr is introduced into the retort via inlet port 24 by opening inlet valve 25. Upper 28 and lower 29 outlet valves are held open to allow air to escape from within the retort 2, in. an operation called venting. When the ret it reaches a temperature of approximately 100'C and quantities of stear are.

issuing from upper and lower outlet ports 26 and 27, the lower otji et valve 29 is dosed and steam is allowed to issue from upper outlet ] ot 26 for a further predetermined period before the upper valve 28 is als closed. Venting schedules, i.e, the intervals between opening valve 25 and closing valves 28 and 29, are preferably determined experimentally for each retort.
The retort now comes up to the required process temperature with he flow of steam -through the inlet valve 25 being controlled by a ccm.tr »1 circuit 34 responsive to a, temperature sensor 35 positioned within t' e retort 2, Once the required temperature in the retort is reached, the iming of the process starts.
At the end of the predetermined process time, inlet valve 25 closes to stop the flow of steam into the retort 2, and air from purging inlet port 3{ is introduced via purging valve 31 to sweep steam from the retort, while maintaining the pressure at the levd used during the heating proceg This is controlled using pressure sensor PI, with steam being exhausted through the upper and/or lower outlet ports and valves.
when enough steam has been swept from the retort and been replaced with air, cooling can commence by use of sprays of cooling water from nozzles 33 in spray bar 32 fed by water from valve 34 If too much st am is left in the retort when cooling starts the cold water will condense the steam and the pressure in the retort will drop excessively.

As cooling proceeds the pressure in the retort is allowed to fall sloly back to atmospheric Once the cans are cooled, usually down to ab out 40"C, the retort is opened and the cans unloaded. Typically the total cycle time is about 15 minutes. It is possible to use the system for contair are other than metal cans, though because of their robustness and high thermal conductivity they are the preferred container.
In. a retort thai uses steam fox heating and sprays of cold water for cooling, the major thermally induced stress will occur when, the steam contrcts cold areas of the retort during the heating phase, and when cold wa er contracts hot areas of the retort during cooling. Areas of particular concern are where there are welds and changes of section.
It is, therefore, proposed that the retort pressure vessel be protected from large thermal shock loads firstly by shielding it from the cooling water and/or secondly by pre-heating it at the start of the day or at the start of each operational period. Its temperature will only fluctuate by a relaively small amount over the working period.
Coolant shielding
In the illustrated embodiment of Figures 1 and 2, the cooling water sprayed from nozzles 33 is prevented from contacting -the hot interns surfaces of the retort so that all areas; of the retort are maintained at a high temperature throughout the process cycle (say greater than 1006). Should plates 37 are arranged to extend longitudinally within the retort outs; be the path of the cage 12; the lower edges 37a of the shield plates 37 being arranged above a sump tray 38 which extends below the rails 11. The

positioning and dimensions of the shield plates 37 are such that w. ter sprayed from the nozzles 33 which bounces from the cage 12 and c ins 14 impinges on the shield plates and runs down into the sump tray 31 The sump tray drains through a drain 39 controlled by a, drain valve 40 which is dosed while the retort is pressurised, preferably after the lower \ alve 29 in the venting stage, and opened to allow coolant to exit during the cooling phase of the cycle. Until the pressure within the retort has t sen sufficiently reduced, opening of the valve 40 will be controlled so a not to allow sudden depressurisation but to permit a sufficient rage of egress of coolant to prevent overflowing of the sump tray 38. One or more sensors may be provided in the sump tray, linked to the control cirecntry fox the drain valve 40, to increase opening of the drain valve 40 as tl e level of liquid in stunp tray 38 rises.
The shield plates 37 may be mounted to the interior of the retort wa ,,
preferably on thermally instilated mountings 41, as shown at -the rig it-hand side in Figure 2. Alternatively, the shield plates 37 may be irv-tirned, as seen in Figure 2, to ensure that water flowing from the plates 37 v ill fall into the sump tray 38. When the plates 37 are mounted on the cage cages) 12, then the sump tray must be dimensioned so that water flo wing OR dripping from the plates 37 falls into title tray 38 irrespective of the reciprocating motion of the cage 12 and plates 37,
The shield plates 37 may be of solid metal or plastics sheet material, may be formed from foam or mesh materials, provided that they are of a pore or mesh size effective to prevent droplets or streams of coolant rom impinging on iihe retort wall. A mesh having openings of 1mm or less

preferably 0.5mm or less, and most preferably 0.25mm or less, in ameter is effective as a shield against rebounding droplets.
In an alternative arrangement, the shielding may be effected by ap] lying an impervious layer of thermally insulating material to the interior of the retort wall, to prevent contract between the coolant and the wall.
It is also preferred to thermally isolate ihe pipes bringing in and car ying away cooling water from the body of the retort, by surrounding ihe Apes with thermal insulation at their points of passage through the retort There is a risk that during the cooling phase of the process cycle the shields provided to keep the cooling water from contacting the hot alls of the retort are not totally effective, and may allow cold water to flc onto the interior of the retort walls, cooling them locally at the point of contact. The present invention provides for monitoring means to det to failures of the shielding, as seen in detail in Figure 3. The monitoring means comprises, in the illustrated embodiment, a trap 43 formed by a tube 44 closed at its lower end 44a and fixed into the lowermost part )f the wall, 4 of the retort 2 to form a downWardly-extendirvg trap, open to t the interior of-the retort The retort 2 is arranged so that any coolant spra which strikes the interior of the retort will run down into ihe trap 43. Che trap 43 is provided with, a coolant sensor45, which may be a level sen or or a capadtive sensor, to detect coolant collected in the trap. The cool xvt sensor 45 may provide detection signals to the control circuit 34, or in tybe an independent unit providing audible or visual detection signals by sounding or display device. The trap 43 has a drain valve 46 for empting

the trap prior to use, which may be controlled manually or by the c >ntrol circuit 34.
Before each cooling cycle, the drain valve 46 is opened to dear the t ap 43 of any condensate, and is then re-dosed. If any coolant runs into fh At ihe start of the cycle, ie. with the retort 2 open ready to be loadec with. cans, the drain valve 46 on the trap 43 is opened to ensure the trap is empty. If it is not, the control circuit 34 will cause a warning to be given, and the process cycle will not be allowed to commence.
Once the retort 2 is loaded, the door 7 closed and the steam, supply torned on by opening the inlet valve 25 to start the heating process, the drai valve 46 on the trap 43 closes. As the heating process proceeds consate v/ill run down, the wall 4 of the retort and start to fill the trap 43, and the rise in the level of liquid in tube 44 will be detected by the sensor 45, nd monitored by Hie control circuit 34. The signals from sensor 45 may be compared with signals from previous heating cycles by the control circuit 34, to ensure the readings are typicaL This can not only check that the level sensor is working, but may also serve to indicate that nothing untoword is happening during the heating phase if the sensor signals substantial correspond to those of earlier process cycles. If different results are obtained, e.g. if larger amounts of condensation from the steam supp y detected, this may indicate unusual heat losses from the retort that couald

prejudice the process, or may indicate excessive amounts of liquid vater in the steam.
At the end of the heating stage of the process cycle air is introducec tiirough purging valve 31 to sweep the steam from the retort and n :>lace it with air before cooling can begin. During this phase the dram valve 46 on the trap 43 is opened and the condensate drained away until the sex sox 45 detects the trap to be empty, whereupon the drain valve 46 is closec
The cooling phase now begins During normal operation no coolant YI drain into the trap 43 and the sensor 45 will confirm this to be the ca e. If, however, the coolant is not all caught by the shields 37 and sump trt y 33, the trap 43 will start to fill and the coolant in trap 43 will be detected by the sensor 45, The control circuit 34 will then alert the operator to fhi abnormal situation, and may be programmed to allow the cooling pi ase to be completed but not allow the next cycle to commence without authorised interveatiotion
As an alternative to detecting the level of liquid coolant in trap 43, th coolant may have an additive such as a dye or chemical tracer which nay be detected visually through a window in tube 44, or the sensor may be arranged to detect the tracer chemically by analysi9 of the trap ranter . For example, the coolant may include an additive which makes the p I of the coolant different from the usual condensate, and maybe detected by testing the pH of the trap contents with litmus. Condensate from the heating process will not contain the additive, and thus presence of flu

additive in trap 43 will indicate shield failure without necessarily laving to drain the trap before each cooling cycle,
la a preferred embodiment, the functions of the trap 43 and the lo\ -er outlet 27 may be combined, by providing a coolant sensor 45 at fh* outlet 27 upstream of the lower outlet valve 29, Downstream of the lowei outlet valve, a diverter arrangement will be provided to vent steam from he lower outlet valve to atmosphere, and to direct coolant either to a suitable drain., or to a refrigeration or heat exchanger circuit for cooling and recycling.
In a water spray heating and cooling retort, the cans in the retort ar heated not by filling the retort with steam, but by spraying the cans with hot water. Cooling is effected by spraying with cold water as descri »ed above. By providing the shielding described above both for the hot .nd the cold water, the retort walls are at all stages isolated from contac with the hot and cold liquids, greatly reducmg the thermal cycling of the retort and extending its life, The shield failure sensor described above will be effective to detect hot as well as cold water impinging m the retort wall,
Pre-heating
The retort may additionally or alternatively be operated using a regine which minimises the thermal shock to the retort at the start of the precess cycle. This is particularly suitable to retorts heated by steam or stear/air mixtures, and is achieved by slowly pre-heating the retort prior to charging the retort with cages of cans. An example of such an operating regime would be as follows:

With the retort empty of cans and cages the door is closed and the preheating step commences, in which the temperature of the retort is raised slowly to 100aC over a time that is dependent on the initial temperature of the structure of the retort by partially opening then let valve 25 to admit a limited flow of steam. The colder the retort, the onger is the pre-heating time, preferably up to a maximum of about 5 min ites. The exact time required to preheat any particular retort form an inital temperature to its operating temperature will preferably be determined by experiment. As the initial temperature of "the retort may not be known precisely, it may be estimated from the length of time since the end if the last process cycle together with a knowledge of the cooling rate of the structure. From this estimate the required length of pre-heat can be determined.
When the retort reaches 1006C the steam supply is then turned fully (inlet valve 25 fully open) to correctly vent the retort for, say, ten sea ads before the Lower outlet poxt 27 is closed followed by a further ten seconds, say, before the upper outlet port 26 is closed. The steam supply is immediately reduced, by partially closing the inlet valve 25, to a leve such that it will take the retort a further two minutes or so to reach process temperature and pressure. (For a given installation the required inter al us conveniently determined by experiment).
The process foxier is now started and foe process continues for as long as experiments have determined to be necessary to raise the fabric of the retort substantially to Its working temperature.

The steam supply (inlet vale 25) is then turned off and the upper or (let port 26 opened slowly to allow the steam to escape from, the retortnd reduce the pressure to zero. The pre-heated retort is ready for loading with one or more cages for cans for production.
The slow pre-heating of the retort is done to avoid ihermal shocks curing this operation and as the retort is hot when production commences, thermal shock loads are significantly reduced. Control of the valves 5, 28, 29,31,34 and 40 is preferably affected by the control circuit 34, which may be a process controller, a programmable microprocessor or a person computer or the like.
To ensure that the retort is always at a sufficiently high temperature :o avoid these shock loads the time from the end of the previous proce: 3 is measured. If it is too long the control circuitry 34 controlling the while operation of the retort is preferably arranged so as not allow the nex process cycle to commence until the retort is again pre-heated. The exact length of the pre-heating required varies, depending on the time tha has lapsed since the end of ih,e last process and other factors such as amlient temperature. The actual length of the pre-heat required is determine by experiment, and preheating times for various intervals since last use nay be stored in memory accessible to the control circuit 34
The control circuit 34 may be arranged to cause an audible or visual warning to be given before the end of the time interval after a heattn ; cycle in which a further heating cycle may be started without pre-he ting the retort, so that the operator can decide whether there is time to load the

retort and start the next process or whether he needs to carry out s preheat cycle.
Can Loading and Positioning,
To achieve consistent process results, each container or can 14 must be
held securely and in its correct position with respect to its neighbours.
A method and apparatus for stacking cans 14 into their cages 12 is row described with reference to Figure 4, and is applicable to hand loaded semi-automatic or fully automated processing installations.
The cage 12 is loaded with cans 14 by placing a layer mat 15 in, a horizontal position in the cage, with its studs 16 extending upwardh There is provided for each can in a layer, an array of studs arranged round the perimeter of a circle whose diameter corresponds to that of a can 14, at preferably equiangular but possibly irregular spacing. Most preferat y four studs are provided for each carv but in alternative embodiments iircee or fewer, or five or more, studs may be used. For cans of non-circtala] section, an. array of studs arranged to suit title cross-section of the can is provided.
The uppermost and lowermost layer mats 15 are preferably provided with studs on one face only, while intermediate layer mats, intended to be positioned between two layers of cans 16, have studs on both faces.
In the example shown each can 14 is located within the cage 12 by eig it cone shaped studs 16, four studs being attached to each of two layer I LATS

15 to locate respective ends of the can 14 The studs 16 have a cylir drical base section 16a and a conical tapered top section 16b ending in a as rounded tip 16c, The spacing of the studs is arranged to receive a particular and closely between each set of four studs. The minimum separation djtance S between adjacent cans 14 in a layer is, in the embodiment shown, equal to the diameter of the base section 16a of a stud 16, since the studs are arranged in ranks and files aligned with the ranks and file, of cans: 1 a layer, Alternative arrangements where studs are positioned so that each stud contacts three or four, rather than two, cans 14 are possible, using staggered rows of cans in each layer. The size and shape of the stud ; 16 is such that during ihe operation of loading cans into ihe cage, the corcal top sections 16b act as lead-in surfaces, and the cans are positioned accurately by contracting the base sections 16a of the studs 16. The cans 14 are loaded by placing ihe end of the can between the studs 16, If the and edge of the can contacts the conical top section 16b of a stud, the car will, be guided to its correct position. If a can is placed with the rounded ip 16c of a stud contacting the end of the can, as seen in chain lines in Figu 5 4, then the can will preferably be sufficiently misaligned as to interfere with at least on of its neighbours, and miss-loading will be apparent to ax operator. If this situation is not corrected it may also prevent fhe correct positioning of the next lay mat 15, making miss loading apparent. the present system is, however, tolerant of missing cans. Indeed this is a significant feature as it is almost certain to happen in practice. During loading the cans are arranged with, their axes vertical and with the layer mats 15 horizontal For loading into the retort 2, the cage 12 may be laid on its side so that, in. contrast to the example shown, the axes of the cans 14 are horizontal and parallel to the cylindrical axis of the retor i.,e

the axes of the cans extend in the direction of their reciprocating movement during agitation.
The cans 14 are preferably arranged in 'sticks' of axially aligned cans, with a gap between each two adjacent cans in the stick formed by file laer mat The layer mat may have an embossment or step on which each study 16 sits. In the preferred arrangement, the 'sticks' of cans extends horiz mtally in the retort, in the agitation direction, A clearance of about 10mm, >r possibly more, is provided between each stick of cans and its neigh out in the horizontal direction, sufficient to allow free flow of heating and ooling fluids. In the vertical direction each stick is preferably positioned di ectiy over the one beneath with a clearance space of about 3mm, or more between sticks. Such an arrangement gives good flows of both steal and water over the cans, though other arrangements may be satisfactory
It should be noted with respect to the loading and location of the cans that cans may be cylindrical, so that the outside diameter of the two ends of the can are substantially equal, or the diameters of the ends of the can may differ by an amount of 2xnrn or more.
To locate cylindrical cans, or cans whose end diameters differ by about 2mm or less, the same layout and spacing of studs is preferably used for both ends of each can. Most preferably, studs on opposite faces of the layer mat will be coaxial, with the stud layout adopted being that fox the larger of the two diameters if different. If the difference in diameter is great r than about 2mm, the spacing and/or layout of the studs may be varid as appropriate for each can end. Necessitating that the cans be loaded it a

predetermined orientation. If this is not done correctly it will be d ar to the loader either at this stage or when the next layer mat is positio .ed.
The cage may be loaded either by hand or by using a semi or fully automated system. The description below is for an entirely hand k ded operation-First the cage 12 is positioned with an open side upward, and a bat om layer mat 15 is placed in position to form a base, with the studs 16 projecting upwards,
The first layer of cans 14 axe then loaded by standing each can 14 oi the layer mat 15 with the end of the can positioned by an array of studs 16 on the layer mat, each stud engaging the edge of the can. When a first] yer is completed, an intermediate type layer mat, having both upwardly extending and downwardly extending studs 16, is lowered vertical through the open side of the cage 12 to rest in a horizontal plane on he tops of tiie cans of the first layer. The layer mat may guided in the horizontal plane by the corners of the cage 12 so that the downward y extending studs 16 easily engage the edges of the cans, ensuring secore location of each
The second layer of cans is then loaded in a manner similar to the first and another intermediate type layer mat lowered into position. The proc dure is repeated until ttve cage is full, when the top layer mat, 5, being of the same type as the bottom mat 3 but with its studs extending downwads, is

added. A rdeasable clamping arrangement can then be used to se ure the layers of cans and their interposed layer mates 15 in position in fti cagel2.
The loaded cage 12 is then positioned in the correct orientation on trolley ready to be loaded into the retort. The cage is preferably loaded in other retort with the layer mats in vertical planes, holding the cans 14 with. their axes horizontal and aligned with the reciprocation movement direc ion of the cage, when the cans have, an axial length equal to at greater tha their diameter (or a representative transverse dimension or 'width in the case where the cans are of non-circular cross-section). However, if the cans are of a squat shape where the axial height is less than their diameter 0,1 'width', a more effective orientation may be to keep the cans with their axes vertical or substantially vertical.
For non-circular section containers, similar considerations apply the if the containers are squat in height and rectangular in cross-section they are preferably oriented with the reciprocation, direction aligned with flu longest transverse dimension.
It should also be noted that for squat containers, whether reciprocate i in a direction parallel to thheir ends or at right angLes to them, layer mate 5 with studs 16 on just one side may be used not only at the top and be torn, but also as intermediate layer mates for locating the containers.
The method of hand loading described is necessarily limited to cages of a depth, sufficiently shallow that the bottom layer can be reached. For deeper cages a semiautomatic system needs to be employed.

For example, the cage may be placed on a suitable frame over a jacking arrangement that lifts up the bottom layer mat to a position near the open top of the cage, allowing for easy loading of the cans. Once the firs layer of cans is loaded, the jack is operated to lower this layer of cans by mat is amount equivalent to the height of the layer. An intermediate layer mat is then added followed by the next layer of cans. the procedure is rejeated until the bottom layer mat is positioned at the bottom of the cage, whereupon the top layer mat is placed over the uppermost layer of cans A clamp may then be used to lock the cans and mats in place.
Such cage loading arrangements using jacking mechanisms of this t 'pe are conventional in the catuning industry, and can be used to load any size of
cage.
A fully automatic version could be envisaged using similar prindpl s, but instead of hand loading the cans into each layer an automated 'pick ind place' unit would be
INDUSTRIAL APPLICABILITY
The invention is applicable throughout the canning industry which 5 an industry of major importance in a large number of countries. Apartom providing for more rapid sterilisation of a given load of filled cans and so a greater throughput in a given time period) it reduces by a substanal amount the heat required in the step and so the fuel cost.

CLAIMS
1 Apparatus for heat-treating products, comprising: a retort b to
wfruch the products to be treated ate receivable; heating m&t is for
heating the retort; coolant spray mear\s for spraying a liquid coolant
onto products received in the retort; and, shielding means to
substantially prevent coolant sprayed from the coolant spra^ means
from impinging on the interior of the retort.
2 Apparatus as claimed in Claim 1 wherein the shielding mear
comprises one or more plates of solid metal or plastics sheet
material.
3 Apparatus as claimed in Claim 1 wherein the shielding mean
comprises foam or mesh material having a. pore or mesh size
effective to prevent droplets or streams of coolant from impir 5ing
on the retort wall
4 Apparatus as claimed in any preceding claim wherein the shi Iding
means comprises an impervious layer of thermally insulating
material,
5 Apparatus as claimed in any preceding claim wherein the shit ding
means includes a sump tray mounted at a lower region of the etart
and having a drain conduit extending through ihe retort wall o
drain liquid from the tray, and a plurality of vertically extendi xg
plates positioned with their lowermost edges above fee sump ray

so that liquid impinging 011 the plates v/ill be collected in tb • sump
tray,
6 Apparatus as claimed in any preceding claim wherein the tetort
incorporates agitating means for applying a reciprocating mation to
products received in the retort
7 Apparatus as claimed in any preceding claim wherein the shuelding
means is fixed relative to the retort
8 Apparatus as claimed in any preceding claim wherein the tetort
incorporates a carrier for supporting products within, the tetort and
movable relative to the retort, and wherein at least one of the plates
of the shielding means is mounted on the carrier.
9 Apparatus as claimed in any preceding claim wherein the tetort is
provided with trap means at a lower part of the tetort adapter to
catch coolant liquid impinging on the retort wall due to faild 2 of
ihe shielding means, and a selectively openable drain valve is
coiranionication with tive trap and openable to drain liquid fro in the
trap.
10 Apparatus as claimed in Claim 9 wherein the trap means
Incorporates a sensor for detecting the presence of liquid in tti \ trap
means such as a level sensor or a sensor adapted to detect a
constituent of a liquid coolant composition.

11 Shielding apparatus for a retort comprises a retort wall defi ring a
volume into which products to be treated are receivable, he ting
means for heating the retort, and coolant spray means for sj raying
aliquid coolant onto products received in the retort, and shielding
means moutitable within the retort to substantially prevent" quid
coolant sprayed from mountable coolant spray means from impinging on
{he interior of tlie retort wall.
12 Shielding apparatus as claimed in Claim 11 wherein, the hielding
means comprises one or more plates of solid sheet material.
13 Shielding apparatus as claimed in Claim 11 wherein the shie] ling
means comprise foam or mesh material having a pore or met size
effective to prevent droplets or streams of coolant from impringing
on the retort wall.
14 Shielding apparatus as claimed in Claim 11 wherein the shielding
means comprises an impervious layer of thermally insulating
material
15 Shielding apparatus as claimed in Claims 11 to 14 wherein -the
shielding means includes a sump toy mounted at a lower reg on of
the retort and having a drain conduit extendable through the etort
wall to drain liquid from the tray, and a plurality of vertically
extending plates positionable with their lowermost edges above the
sump tray so that liquid impinging on the plates will be collec ed in
the sump tray.

16 A method of protecting a retort comprising a retort wall d fining a
volume into which products to be treated are receivable, h atitig
means for heating the retort, and coolant spray means for 5 graying
a liquid coolant onto products received in the retort agajns thermal
shock, the method comprising the step of mounting shieldi ig
means within the retort to prevent liquid coolant sprayed from the
coolant spray means within the retort from impinging on the
interior of the retort wall
17 A method of protecting; a retort as claimed in Qaim. 16 inch iing
the steps of:
mounting a sump tray at a lower region of the retort providing a drain conduit through the retort wall to !rain
liquid from the tray; and
mounting a plurality of vertically extending shield p] ites
within the retort with, the lowermost edges of the plates posi ioned
above the sump tray,
18 A method of protecting a retort as claimed in Qaim. 16 when in the
shielding means comprises an impervious layer of thermally
insulating material; includes the steps of:
opening the drain valve to empty the trap; closing the drain valve prior to a. cooling operation; and establishing shield failure by sensing liquid coolant in the trap after the cooling operation has started,

19 A method of protecting a retort as claimed in Claim 18 whe eiti the step of detecting liquid in the trap comprises either detectir * a level of the liquid therein or detecting a constituent of liquid the* an.
20 Apparatus for locating within a retort a plurality of substan ally
cylindrical, objects having a pair of transverse end walls join d at
their edges to a sidewaU in paraxial layered relation with ob sets
spaced by at least a minimum predetermined spacing distan e from
each, other, comprising; a substantially planar mat having fir t and
second faces; and a plurality of arrays of projections extendi g from
one of said faces, each array being arranged to receive an enc face
of one of said objects there-between in. a location position; wlerein
the height of the projections is so arranged that when one eru face
of an object contacts a free end of a projection/ the other end ice of
the object is offset from its location position.
21 Apparatus as claimed in. daim 20 wherein, the height of the
projections is so arranged that when one end face of an object
contacts a free end of a projection, live other end face of the ot ect is
offset from its location position by at least the miniaimum
predetermined spacing distance.
Apparatus as claimed in Claim 20 or 21 wherein each array comprises three or more projections.
23 Apparatus as claimed in claims 20 - 22 wherein each projection comprises a cylindrical base section and a conical top portion.

24 Apparatus as claimed in Claim. 23 where in the diameter of flu base section corresponds to said minimum predetermined spacing distance,
Dated this 28 day of August 2006

Documents:

3119-CHENP-2006 CLAIMS GRANTED.pdf

3119-CHENP-2006 CORRESPONDENCE OTHERS.pdf

3119-CHENP-2006 CORRESPONDENCE PO.pdf

3119-CHENP-2006 FORM-18.pdf

3119-CHENP-2006 POWER OF ATTORNEY.pdf

3119-chenp-2006 abstract duplicate.pdf

3119-chenp-2006 claims duplicate.pdf

3119-chenp-2006 description(complete) duplicate.pdf

3119-chenp-2006 drawings duplicate.pdf

3119-chenp-2006-abstract.pdf

3119-chenp-2006-claims.pdf

3119-chenp-2006-correspondnece-others.pdf

3119-chenp-2006-description(complete).pdf

3119-chenp-2006-drawings.pdf

3119-chenp-2006-form 1.pdf

3119-chenp-2006-form 18.pdf

3119-chenp-2006-form 3.pdf

3119-chenp-2006-form 5.pdf

3119-chenp-2006-pct.pdf

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Patent Number

230629

Indian Patent Application Number

3119/CHENP/2006

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

27-Feb-2009

Date of Filing

28-Aug-2006

Name of Patentee

ZINETEC LIMITED

Applicant Address

15 Palace Street, Norwich NR3 1RT,

Inventors:

#	Inventor's Name	Inventor's Address
1	WALDEN, Richard	Zinetec Ltd., 22 Highworth Road, Faringdon SN7 7EE,
2	FERGUSON, Robin, Julian	Zinetec Ltd, 22 Highworth Road, Faringdon SN7 7EE,

PCT International Classification Number

A23L3/00

PCT International Application Number

PCT/GB2005/000761

PCT International Filing date

2005-02-28

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0404299.0	2004-02-26	U.K.