AU770774B2

AU770774B2 - Centrifugal cutter equipped with a cooling device, and corresponding process

Info

Publication number: AU770774B2
Application number: AU40298/01A
Authority: AU
Inventors: Olivier Pouchain; Severine Servel
Original assignee: Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2000-05-03
Filing date: 2001-05-02
Publication date: 2004-03-04
Anticipated expiration: 2021-05-02
Also published as: NZ511484A; DE60106512T2; EP1151836B1; FR2808468A1; DE60106512D1; ES2230245T3; FR2808468B1; AU4029801A; EP1151836A1; ATE280016T1

Abstract

The centrifugal cutter consists of a turbine (32), driven in rotation around a vertical axis, with a cylindrical cutting head (50) arranged co-axially around the turbine. An outer case (4) encloses both the turbine and cutting head and has an opening for the supply of non-cut products and an outlet (15) for the cut products. The cutter also has fitted injectors (58, 59) to introduce cryogenic materials into the space occupied by the cut material.

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: L'Air Liquide, Societe Anonyme pour I'Etude et I'Exploitation des Procedes Georges Claude Actual Inventor(s): Olivier Pouchain, Severine Servel Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: CENTRIFUGAL CUTTER EQUIPPED WITH A COOLING DEVICE, AND CORRESPONDING

PROCESS

Our Ref: 641937 POF Code: 1290/43509 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- -IA~ The invention relates to a centrifugal cutter, particularly for food products, of the type that comprises a product-driving impeller rotating about an essentially vertical axis, an essentially cylindrical fixed cutting head arranged coaxially about the impeller, and a casing surrounding the impeller and the cutting head, the casing having a feed opening for uncut products in its upper part, and an exit opening for cut products in its lower part, the cutting head dividing the space defined by the casing into a space for uncut products and a space for cut products.

Centrifugal cutters for food products are known in the state of the art.

Such a cutter generally comprises an impeller 15 that consists of a disc on a vertical axis, rising from which disc are a number of drive walls that extend radially inwards from the circumference of the disc.

The impeller is rotated by a geared-down motor.

A centrifugal cutter also comprises a cylindrical cutting head arranged coaxially about the impeller. The cutting head comprises radial slots that extend over the full height of the impeller. Blades are mounted tangentially on the slots and project slightly inwards.

S* 25 The impeller and the cutting head are surrounded by a casing comprising a feed opening at its upper end, and an exit opening at its lower end.

[[During operation, the cutter is fed with food product. This food product falls onto the disc, is flung radially outwards by centrifugal force, is pressed against the blades by the drive walls, and the blade cuts the product into pieces.

The pieces then fall through the exit opening, for example onto a conveyor.

Centrifugal cutters have the drawback that the periphery of the product becomes locally intensely heated during cutting. This effect gives rise to problems such as the development of bacteria, or clumping of the cut pieces.

2 In order to minimize this effect, it has already been proposed in the state of the art that dry ice, for example, be deposited on the products/pieces before/after the cutter, or that cryogenic fluid be injected into the top of the impeller. However, these measures have not given satisfactory results and still present the following problems: there may be uneven cooling and, in consequence, cutting problems; when the cryogenic fluid used is C02 residual lumps of CO 2 may damage the cutter or cause inflation of the sachets in which the product is wrapped; the lack of control may be a source of technical problems.

Furthermore, the cooling actions mentioned above do not treat the peripheral heating around the cutter. This poorly controlled phenomenon can be a decisive factor in the final quality of the product and in clumping.

It is an object of the invention to reduce the abovementioned problems and to propose a centrifugal cutter that efficiently reduces the effect of peripheral heating of the product.

25 To this end, the subject of the invention is a centrifugal cutter of the abovementioned type, characterized in that the centrifugal cutter also S- includes at least one device for injecting a cryogenic liquid into the space for the cut products.

In accordance with specific embodiments, the invention may have one or more of the following features: the casing has an essentially circular cross section and the direction of injection of the injector device is oriented approximately tangentially to this circular cross section; the direction of injection is away from an approximately radial drive shaft of the impeller; 3 the direction of injection of the injector device is approximately horizontal and countercurrent relative to the direction of rotation of the impeller; the cutter [lacuna] a second injector device arranged on the opposite side of the casing from the first injector device, and the direction of injection of the second injector device is with the direction of rotation of the impeller; the point of injection of the injector device is below the plane defined by the extreme lower surface of the cutting head; the casing comprises thermal insulation over virtually its entire surface; the thermal insulation comprises a double 15 envelope consisting of two stainless steel walls and, between the two walls of the double envelope, a layer of foam plastic; the cutter also comprises, connected to the casing, a device for evacuating the cryogenic gas formed during the injection; the evacuation device is positioned on the upper end of the casing; the cutter also comprises a temperature .sensor that measures a temperature representing the S. 25 temperature inside the casing, and it also comprises a control device connected to the temperature sensor and to the injector device, which control device controls the injector device on the basis of the temperature sensed by the temperature sensor; the cryogenic liquid is liquid CO 2 or liquid nitrogen; and the injector device comprises a stop valve leading into an injector nozzle which is connected to the casing, the valve also being connected to a source of cryogenic liquid under pressure and being actuated by an actuator such as an electropneumatic actuator.

Also forming a subject of the invention is a process for cooling products cut by a centrifugal cutter as defined above, characterized in that 4 cryogenic liquid is injected into the cut-products space of the casing of the centrifugal cutter.

The process according to the invention can include the following steps: at least some of the cryogenic liquid is injected countercurrent to the direction of rotation of the impeller of the centrifugal cutter; the cryogenic gas formed during the injection is evacuated towards the top of the casing.

A clearer understanding of the invention will be gained from the description that is to follow. This is provided purely by way of example and refers to the accompanying drawings, in which: Figure 1 is a front view of a centrifugal 15 cutter according to the invention; Figure 2 is a plan view of the cutter shown in Figure 1 partially cut on line II-II marked in Figure 1; and Figure 3 is a view of detail III marked in Figure 1 on a larger scale, and partly in section.

Figure 1 shows a centrifugal cutter 2 according •co* to the invention.

The centrifugal cutter 2 comprises a casing 4 containing a cutting mechanism 6. It also comprises a 25 box 8 comprising a geared-down motor 10 to which a control and power-supply device 12 is connected.

The casing 4 comprises a lower part 14 of *frustoconical shape having a vertical axis X-X that tapers in a downward direction and is fixed detachably to the box 8 of the geared-down motor 10. The lower part 14 of the casing is open at the bottom at 15 in order to allow the cut product to exit. Additionally the cutter 2 may comprise an exit hopper 16 fixed underneath the exit opening 15 and tapering towards a conveying station 18 located underneath. An upper part of the casing is arranged separately over the lower part 14 and fitted with a known safety device 21. The upper part 20 of the casing comprises a feed tube 22 for uncut product and this is fitted with a conventional grating 24 to protect the hand.

As can be seen in Figure 3, the wall 26 of the casing 4 consists of a double envelope formed by two walls 28 of stainless steel sheet, between which a thermally insulating layer 30 of foam plastic is incorporated.

The cutting mechanism 6 comprises an impeller 32 having a disc 34 on a vertical axis coinciding with the axis X-X of the casing 4. Drive walls 36 rise from the upper surface of the disc 34. The drive walls are positioned on the circumference of the disc 34 and extend radially inwards. The upper edges of the drive walls 36 are connected to an annular disc 38 and- are 15 thus fixed to each other.

The lower face of the disc 34 is integral with a bevel gear 40 meshing with a bevel pinion 42 on the output of the geared-down motor. The bevel pinion 42 is connected to the geared-down motor 10 by a shaft 44 that is surrounded by a protective tube 46 attached to the box 8. The impeller 32 and the bevel gear 40 are **mounted as a unit so as to rotate vertically on a bearing 48.

cylindrical cutting head 50 is arranged 25 coaxially around the impeller 32, separating the enclosure of the casing 4 into a space for uncut products 52 and a space for cut products 54. The [.cutting head 50 comprises radial slots extending for virtually the entire length of the impeller. Cutting blades 56 are mounted on the cutting head in the slots, as is conventional. The cutting head 50 is held in position by a bracket (not shown) fixed to the lower casing 14.

The centrifugal cutter 2 also -includes two devices 58, 59 for injecting a cryogenic liquid into the lower casing 14 (see Fig. The two cryogenicliquid-injector devices 58, 59 are known from, for example, European patent application EP-A-744 578. They each comprise essentially a ball shut-off valve 6 connected by a quick-release coupling 62 to an injector nozzle 64. The ball shut-off valve 60 is connected in this example to a source 66 of liquid C02 under pressure by a line 68 and controlled by an electropneumatic actuator 70 connected to the control device by a corresponding control line 72, 73. The injector nozzle 64 is surrounded by a thermally insulating sleeve 74.

It should be observed that the injector devices 58, 59 are arranged in such a way that their directions of injection Dl, D2 are aimed approximately tangentially to the circular circumference of the lower casing 14. In addition, the directions of injection D1, D2 of the two injector devices 58, 59 are aimed away from the drive shaft 44 of the geared-down motor 10, in order to avoid agglomeration of the dry ice and of the cut product on the protective tube 46 of the drive shaft.

The direction of injection of the injector device 59 is aimed against the direction of rotation R of the impeller 32, whereas the direction of the injector device 58 is aimed in this direction of •coo rotation.

gas evacuation device 80 is connected to the 25 feed tube 22 of the upper casing.

Also, a temperature sensor 82 is positioned on the inside of the lower supplementary hopper 16 in order to detect the exit temperature. This sensor 82 is connected to the control device 12 by a sensor line 84.

As a variant, the temperature sensor may be placed in other locations, for example above the impeller 32.

The centrifugal cutter according to the invention operates in the following manner.

When the cutter 2 is put into operation, the control device 12 monitors, via the sensor 82, the temperature in the hopper or in the casing 4 of the cutter. When the temperature is above a predetermined temperature, for example above -150C, injection of 7 liquid C02 is initiated by the control device 12. C02 injection is effected in short cycles of injection/pause. The C02 is expanded and becomes dry ice which is sprayed onto the wall 26 of the casing 4.

Because the injection is tangential, a "mist" of dry ice and carbon dioxide gas therefore forms inside the casing. When the food product is introduced into the centrifugal cutter 2, the product is cut by the cutting head 50 and falls through the mist. The fiist immediately and uniformly absorbs the heat of the finely cut product dispersed through the cut-products space 54 of the casing. The effect of peripheral heating is thus greatly diminished, as is the formation of residual lumps of dry ice.

15 The fact that the injection is done countercurrent by at least one injector device 59 helps to distribute the dry ice inside the casing 4 and further improves the efficiency of the cooling process.

The cut and chilled food product then falls onto the conveying station 18 and can be packaged with less risk of clumping.

S.The formation of cryogenic gas renders the enclosure of the casing 4 inert and prevents aspiration :."*through the lower opening 15 of the casing of air entrained by the rotation of the impeller 32 and by the evacuation device 80. This prevents the product from being reheated by the in-drawn air. Additionally, the movement of the cryogenic gas towards the feed tube 22 increases the thermal exchanges and cools the product before it becomes cut up at this point.

Lastly, the carbon dioxide gas is aspirated by the aspiration device 80 and expelled out of the production building in order to avoid any danger of asphyxiation of workers.

As a variant, the centrifugal cutter may also be equipped with a single cryogenic liquid injector device 59. In this case, the injector device 59 is positioned so as to inject against the rotation of the 8 impeller 32 and on the opposite side of the drive shaft 44.

Instead of CO 2 it is also possible to use liquid nitrogen for the-cooling.

It should be observed that the injector devices can also be retrofitted on existing centrifugal cutters that have already been installed on a production line.

It will be seen that the injector devices are inexpensive, small and do not lengthen the production line.

The devices are safe and reliable in use.

The cutter according to the invention can be used to produce all the following food products: flatcut or wavy-cut apples, nuts, grated cabbages, grated carrots, potatoes, hard and soft grated cheese and meat sticks. This list is not of course exhaustive.

Throughout the description and claims of the specification the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

Claims

1. A centrifugal cutter, particularly for food products, of the type that comprises a product-driving impeller rotating about an essentially vertical axis, an essentially cylindrical fixed cutting head arranged coaxially about the impeller, and a casing surrounding the impeller and the cutting head, the casing having a feed opening for uncut products in its upper part, and an exit opening for cut products in its lower part, the cutting head dividing the space defined by the casing into a space for uncut products and a space for cut products, wherein the centifugal cutter also includes at least one device for injecting a cryogenic liquid into the space for the cut products. S*

2. A cutter according to claim 1, wherein the casing has an essentially circular cross section and in that the direction of injection of the injector device o• 15 is oriented approximately tangentially to this circular cross section.

3. A cutter according to any one of the previous claims, wherein the i direction of injection is away from an approximately radial drive shaft of the impeller.

4. A cutter according to one of the previous claims, wherein the direction of injection of the injector device is approximately horizontal and countercurrent relative to the direction of rotation of the impeller.

A cutter according to claim 4, wherein it comprises a second injector device arranged on the opposite side of the casing from the first injector device, and in that the direction of injection of the second injector device is with the direction of rotation of the impeller.

6. A cutter according to any one of the previous claims, wherein the point of injection of the injector device is below the plane defined by the extreme lower surface of the cutting head.

7. A cutter according to any one of the previous claims, wherein the casing comprises thermal insulation over virtually its entire surface.

8. A cutter according to claim 7, wherein the thermal insulation comprises a double envelope consisting of two stainless steel walls and, between the two walls of the double envelope, a layer of foam plastic. W:;janiceo\specGay 641937.doc

9. A cutter according to any one of the previous claims, wherein it also comprises, connected to the casing, a device for evacuating the cryogenic gas formed during the injection.

A cutter according to claim 9, wherein the evacuation device is positioned on the upper end of the casing.

11. A cutter according to any one of the previous claims, wherein it also comprises a temperature sensor that measures a temperature representing the temperature inside the casing, and in that it also comprises a control device connected to the temperature sensor and to the injector device, which control device controls the injector device on the basis of the temperature sensed by the temperature sensor.

12. A cutter according to any one of the previous claims, wherein the -:•cryogenic liquid is liquid 002 or liquid nitrogen.

13. A cutter according to any one of the previous claims, wherein the injector 15 device comprises a stop valve leading into an injector nozzle which is connected to the casing, the valve also being connected to a source of cryogenic liquid under pressure and being actuated by an actuator such as an electropneumatic actuator.

14. A process for cooling food products finely cut up by a centrifugal cutter according to one of the previous claims, wherein cryogenic liquid is injected into the cut-products space of the casing of the centrifugal cutter.

A process according to claim 14, wherein at least some of the cryogenic S. liquid is injected countercurrent to the direction of rotation of the impeller of the centrifugal cutter.

16. A process according to claim 14 or 15, wherein the cryogenic gas formed during the injection is evacuated towards the top of the casing.

17. A centrifugal cutter according to claim 1 substantially as hereinbefore described with reference to any of the figures. W:janice~specGay 641937.doc

18. A process according to claim 14 substantially as hereinbefore described with reference to any of the figures. DATED: 2 May, 2001 PHILLIPS ORMONDE FITZPATRICK Attorneys for: L'AIR LIQUIDE, SOCIETE ANONYME POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES GEORGES CLAUDE to 0* *too W:'anice\speckGay 641937.doc