A CONTINUOUS RETORT

Abstract

An apparatus for heat treatment of a product, in particular food product, and especially food product in a container such as a can, bottle or plastic pouch is disclosed. The apparatus comprises an unloading and loading section, a first treatment section having an inner wall defining a processing volume within which product is heated, a transfer section and a second treatment section having an inner wail defining a processing volume within which product is cooled, multiple carriers for retaining product during treatment designed to provide multi-stage pressure reductions that collectively reduce the maximum over-pressure within the apparatus to ambient pressure and thereby eliminate the need for sealable pressure doors or gate valves. The loading section incorporates means of linear movement of said product carriers in a continuous fashion. The carriers includes elements to create cavities between or within successive carriers and a plurality of throughapertures to force heat treatment fluid into direct contact with product as it flows from over ambient to ambient pressure. A heat exchanger recovers energy from cooling product and continuously re-applies that energy to heat product.

Claims

1. An apparatus for heat treatment of a product, by a heat treatment liquid, in particular food product, and especially food product in a container such as a can, glass bottle or plastic container, tray or pouch, the apparatus comprising a Loading Section, a First Treatment Section, the First Treatment Section having a wall defining a generally horizontally deployed small-diameter pressure vessel within which Product is heat-treated, a Transfer Section, a Second Treatment Section, the Second Treatment Section having a wall defining a generally horizontally deployed small-diameter pressure vessel within which Product is cooled, and an Unloading Section adjacent to said Loading Section the pressure vessel having no doors or gate valves; multiple Product Carriers moving sequentially through the various sections for retaining product during treatment pushed by a propelling means; a Product Carrier being so shaped to create a fractional drop in pressure of heat treatment fluid, multiple Product Carriers of sufficient number in each Treatment Section such that said fractional pressure drops cumulatively equal the total pressure drop across said Treatment Section eliminating the need for gate valves or pressure doors, the apparatus including restraining means insertable between Product Carriers as successive loading and unloading pistons return for a Product Carrier; a Product carrier including through apertures to provide water channels surrounding Product being heat treated and direct water onto a Product surface; pumps, heat exchangers, valves, manifolds, and conduits within which heat treatment fluids are transported between different locations within said Treatment Sections.

2. An apparatus in accordance with claim 1, wherein the propelling means incorporates rotation means engaging linkage means on a Product Carrier.

3. An apparatus according to claim 2, wherein a Product Carrier includes further linkage means to engage corresponding linkage means on an adjacent Product Carrier.

4. An apparatus according to claim 3, wherein the propelling means is a piston or linear drive.

5. (canceled)

6. An apparatus according to claim 4, rotation means includes a spiral bar, mounted r rotation and operably linked to rotate the piston as the bar rotates.

7. An apparatus in accordance with claim 1, wherein the apparatus includes at least one Multi-stage counter-flow Heat Exchanger to at least partially recover energy from the cooling of Product in said second Treatment Section and transfer said energy to aid the heating of Product in said First Treatment Section in that cooling fluid has to flow in the opposite direction to the product direction whereas the high temperature fluid surrounding the product as it leaves the first treatment section flows in the same direction as the product.

8. An apparatus in accordance with claim 7, incorporating at least one Magnetron to transmit microwave energy to assist in the heating of Product.

9. An apparatus in accordance with claim 7, wherein a Treatment Section includes double jackets within which heat transfer fluids or gases can circulate.

10. An apparatus in accordance with claim 7, wherein a Product Carrier is 3D printed or machined from a high temperature polymer.

11. An apparatus in accordance with claim 7, wherein individual sector pressure can be controlled and regulated using injection, bypass or exhaust manifolds mounted on the outside of the treatment chambers linked to other sources of fluids with the required conditions using control valves.

12. An apparatus in accordance with claim 7, wherein said Treatment Sections and Product Carriers are cylindrical.

13. An apparatus according to claim 7, wherein each product carrier incorporates recesses to engage with ratchet means located within said tubular treatment section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The invention is now described with reference to the accompanying drawings, which show by way of example 3 embodiments of a retort apparatus and three embodiments of a product carrier. In the drawings:

[0065] FIG. 1 illustrates a typical multi--stage pressure reduction control valve;

[0066] FIGS. 2a-2c illustrate typical steam turbine labyrinth seal arrangements;

[0067] FIG. 3 illustrates multi-stage pressure reduction using multiple product carriers;

[0068] FIG. 4 illustrates external manifolds linked to treatment chambers;

[0069] FIG. 5 illustrates external manifolds linked to a multi-stage contraflow heat exchanger;

[0070] FIG. 6 illustrates a continuous retort apparatus with two treatment sections with linear transfer sections;

[0071] FIG. 7 illustrates sectional views of another type of two section continuous retort apparatus with rotary transfer sections;

[0072] FIGS. 8a, 8b illustrate sectional views of the product carriers within a treatment section;

[0073] FIG. 9 illustrates a Product Carrier;

[0074] FIGS. 10a and b illustrate types of product carrier;

[0075] FIG. 11 illustrates a 12 tube, 6 treatment section continuous retort apparatus; and

[0076] FIG. 12 illustrates a 4 tube continuous retort apparatus with full heat recovery.

DETAILED DESCRIPTION OF THE INVENTION

[0077] As set out above, prior art batch retorts suffer from a number of disadvantages, such as inaccurate processing, particularly with steam/air or steam/water retorts, low processing speed, complex loading and unloading systems and a large overall apparatus footprint for any given throughput. Further, full-immersion water batch retorts use very large quantities of water and energy.

[0078] Prior art continuous retorts have high throughputs for any given footprint but suffer from insufficient variability of pressure control during heating and cooling. In addition, spiral and reel continuous retorts are inflexible in relation to different product sizes and are energy inefficient due to the need to continually vent steam in order to remove entrained air.

[0079] The present invention seeks to address these problems through the provision of a continuous retort apparatus having fully variable over-pressure during all treatment phases with the ability to easily size change between product of differing sizes and shapes. The apparatus can heat treat all types of retort packaging at high as well as low throughputs within a small footprint and in a highly energy efficient way.

[0080] In a preferred embodiment, the present invention is also designed to be used in conjunction with magnetrons to further increase throughput using microwave energy in addition to convective and conductive heat energy in order to minimise the damage to flavour, nutrition, texture and appearance a caused by thermal processing where the product is contained within non-metallic packaging and the product carriers are manufactured from non:-metallic materials such as 3D printed thermoplastics. In the hereindescribed embodiment, magnetrons are illustrated as being attached to a Transfer section to effect heating of product therein. However, magnetrons can be utilised at other stages of the heating process to provide rapid and localised heating and cost-effective heating.

[0081] The apparatus 67 in its simplest form and with reference to FIGS. 6-9, comprises four fully-flooded modules as follows: [0082] a Loading Section 61 within which individual Product Carriers 73 are loaded with Product 72, prior to transferring, by the action of a Loading Piston 60 or other loading means in the direction shown by the arrow 70 to; [0083] a First Treatment Section 62 for the heating of Product 72 within which successive Product Carriers 73 are aligned along the central longitudinal axis of said First Treatment Section 62 such that as each new Product Carrier 73 is introduced into a Product Carrier aperture 69 from said Loading Section 61 all Product Carriers 73 within said First Treatment Section 62 are moved along the said central longitudinal axis away from said Loading Section 6:1 towards and against the pressure gradient 71; [0084] a Transfer Section 64 where Product Carriers 73 are transferred in the direction shown by the arrow 74, and within which individual Product Carriers 73 are pushed from said First Treatment Section 62 by the action of said Loading Piston 60 within said Loading Section 61 prior to being transferred by the action of a Rotary Transfer Motor 68, Linear Piston or other means to align with the central longitudinal axis of; [0085] a Second Treatment Section 63 for the cooling of Product 72 within which successive Product Carriers 73 are aligned along the central longitudinal axis of said Second Treatment Section 63 such that as each new Product Carrier 73 is introduced from said Transfer Section 64 by a Return Piston 65 or other means, all Product Carriers 73 within said Second Treatment Section 63 are moved along the said central longitudinal axis away from said Transfer Section 64 towards an Unloading Section connected to said Loading Section 61 within which Product 72 that has been heat treated is unloaded prior to said Product Carrier 73 being loaded with untreated Product 72, thereby completing the continuous circuit. [0086] At least one Fluid Inlet 66 at the Transfer Section 64 end of each Treatment Section 62, 63 allows hot or cold water to enter the Treatment Sections 62, 63 at the required pressure that will provide pressure equilibrium within said Product Packaging at the temperature the Product 72 has achieved at that position. [0087] At least one Fluid Outlet at the Loading and Unloading Section 61 end of each Treatment Section 62, 63 allows hot or cold water to exit said Treatment Sections 62, 63 at the required pressure that will provide pressure equilibrium within said Product packaging at the temperature the Product 72 has achieved at that position. [0088] As the pressure of the hot or cold water entering each Treatment Section 62, 63 via said Fluid Inlet 66 is always higher than the pressure of the hot or cold water leaving said Treatment Sections 62, 63 there is created a Pressure Gradient 71 which causes the continuous flow of hot or cold water from said Fluid Inlets 66 towards said Fluid Outlets. [0089] Pressure and temperature measurement means located along the length of said Treatment Sections 62, 63 provide feedback to the retorting apparatus' artificial intelligence or other control system and further fluid inlets and outlets located along the length of said Treatment Sections 62, 63 allow localised increases and decreases in the pressure of the hot or cold water according to the temperature profile of the Product 72 as it passes through said Treatment Sections 62, 63 from said Loading Section 61 towards said Transfer Section and back again. Once emptied, a Product Carrier 73 is rotated at 76 back to the Loading Section 6:1 ready to receive further Product 72.

[0090] In FIGS. 8, Product Carriers 73 are shown moving within a treatment section having a double jacket 85. Between the II of the retort and the product Carriers 73 is maintained an inner water gap 82. Each Product Carrier incorporates at least one raised section or element 81 to create a gap between said Product Carrier 73 and its adjacent Product Carrier 73, and said gap creates a Cavity 83 between successive Product Carriers 73 that act as manifolds to help distribute said hot or cold water in the most effective manner for heat transfer as well as the insertion of restraining means as successive loading and unloading pistons return for the next Product Carrier 73.

[0091] Alternatively, the top and bottom surfaces of said product carriers include a plurality of throughapertures 92 such that each product carrier in said alternative arrangement is in direct fluid contact with each adjacent product carrier and has baffles so arranged as to redirect said axial flow of water vertically downward or vertically upward around each product. [0092] Alternatively, the raised elements 81 create cavities 83 to act as manifolds directing heat transfer flows that are perpendicular to the axis of the treatments sections. [0093] Throughapertures within said Product Carriers 73 are such that as the Product Carriers 73 move in the direction of the arrow 80, the throughapertures allow said hot or cold water that is moving in the direction of said Pressure Gradient 84 and which gathers in the Cavity 83 to pass around said Product and thereby heat or cool said Product, or in the alternative gathers in the Cavity 83 above or below the product where the water flow is vertical. [0094] By way of example, if the maximum temperature and pressure of the heating water is 140° C. and 3 Barg and the minimum temperature and pressure is 20° C. and ambient and there are 12 Product Carriers in the intermediate zone between these two sets of conditions the temperature difference between each Product Carrier will be approximately 10° C. and the pressure gradient across each Product Carrier to force the heating water past the Product contained in said Product Carrier will be 0.25 barg. Although the Product Carriers and associated sections can be of any cross-sectional shape, the preferred configuration utilises cylindrical Product Carriers moving through cylindrical sections in order to allow rotation of the product carrier about the longitudinal axis of the tubular treatment section if so desired. [0095] In a preferred embodiment of the present invention, and referring to FIGS. 9, each Product Carrier 90, containing Product 93, incorporates at least one disc 94 which has a greater outside dimension than the body of said Product Carrier 90 to create an area of high speed turbulent water flow. [0096] In a further preferred embodiment of the present invention said discs 94 incorporate raised sections and recesses to allow the transmission of rotary torque action to transmit rotation from the Loading Piston 60 to each successive Product Carrier 90 such that when said Loading Piston 60 rotates then all Product Carriers 90 connected to it preferably also rotate. The cavities or water channels 92, as described previously are shown. In alternative embodiments, a linear drive can be used as propelling means instead of a piston. Other means known in the art can, less preferably also be utilised.

[0097] In one embodiment of the invention, the Loading Piston 60 is connected to a spiral bar, the spiral bar typically comprising a spiral having a 360° turn or greater. In one embodiment, an actuator releasably locks the spiral bar against rotation, and upon translational motion of the Loading Piston 60, the spiral bar does not rotate. Where rotation of the Loading Piston 60 is required, the actuator is released, and as the piston undergoes translation, the spiral bar is caused to rotate, and in so rotating causes the Loading Piston to also rotate. This action therefore acts also to rotate the Product Carriers in the manner described herein. The inclusion of a 360° spiral on the spiral bar results in the Loading Piston 60, and hence the Product Carriers undergoing one full rotation as they traverse the apparatus. [0098] In a further preferred embodiment of the present invention each Treatment Section 62, 63 incorporates a double jacket 85 within which heat transfer fluids or gases can circulate to either heat or cool the inner wall of said Treatment Section 62, 63. [0099] In yet a further preferred embodiment of the present invention energy gained by the heat transfer fluids during cooling of Product in one Treatment Section is transferred to the heat transfer fluids used in heating Product in another Treatment Section via a heat exchanger. [0100] In a yet further preferred embodiment of the present invention said heat exchanger is a mufti-stage contra-flow heat exchanger [0101] In yet a further preferred embodiment of the present invention Product Carriers are manufactured from high-temperature polymers .such as Peek and Pekk using 3D printing techniques. [0102] In yet a further preferred embodiment of the present invention at least one Magnetron microwave energy generator is incorporated within at least one Transfer Section such that when the retort apparatus is processing Product in non-metallic packaging contained in said 3D printed polymer Product Carriers microwave energy from said Magnetron can be used to assist the heat transfer fluids in heating the Product as the Product Carrier is rotated.

[0103] In FIG. 11, a 12 tube, 6 treatment section continuous retort apparatus 1.20 is disclosed, which incorporates means to provide said microwave heating. Product enters the apparatus in the loading section 111. The loading system 113 transfers the product to a carrier, which are then urged into position by means of the loading piston 110. The product then passes along the outermost tube of the treatment section 115, as described above, and undergoing part of the heat treatment, until it reaches the first of the transfer sections 116. The product is rotated within the transfer section 116 to bring it into alignment with one of the neighbouring treatment sections 115. The rotation is driven by transfer motors 117. During the rotation in the transfer section 116, microwave energy is transferred to the product from the magnetrons 119 arrayed on the outside of the transfer sections 116. A return piston 118 then urges the product into alignment for travel along the next stage of the treatment section 115. Treatment continues within the apparatus in a similar fashion, A second array of transfer sections 114 is provided at the opposite ends of the transfer section 115. On completion of the treatment, product leaves the apparatus via the unloading section 112.

[0104] In FIG 12, is shown a 4 tube continuous retort apparatus 141 with full heat recovery, in which two of the tubes are arrayed over the other 2 tubes to provide a more compact structure and to facilitate control of heat energy with in the apparatus. Product is brought into the loading station 131 of the apparatus by the conveyor 130. The product is then transferred to the first of the four tubes of the primary heating section 132 which operates in the manner described above to heat product to the desired temperature in a safe and efficient manner. Product continues along the tube 142 of the primary heating section 131 until it reaches the first vertical transfer station 134. The product is transferred downwards and aligned with a second tube by the second stage piston 135. Passage along the second tube then takes place, and on reaching the end of the second tube, the product is transferred sideways to a third tube and passes along this tube until the product reaches the second vertical transfer station 136 which lifts the product and brings the product to the first end of the fourth tube for the final stage of the heat treatment, cooling the product ready for the product to be unloaded in the unloading section 139. The treated product is transferred to the unloading conveyor 140 to be packaged.

[0105] In order to maximise the use of heat energy, the apparatus is provided with a conduit and manifold system 133 to transfer heat from sections of the apparatus 141 where there is excess heat energy, to where the heat energy is required. multi-stage counter-flow heat exchanger 137 is provided to increase heat efficiency. A secondary cooling system 138 is also provided should it be required.