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Title:
A PROCESSING SYSTEM FOR THE HEAT TREATMENT OF FOOD PRODUCTS AS WELL AS A METHOD OF CONTROLLING A PROCESSING SYSTEM COMPRISING A STEAM BELL
Document Type and Number:
WIPO Patent Application WO/2018/028755
Kind Code:
A1
Abstract:
A processing system (1) adapted for heat treatment of food products (2), wherein a treatment bell (3) is provided with sides (4) and a top (5) which together define a volume (6) from the atmosphere, wherein there is an open connection (8) to the atmosphere below a lower rim (7) of the sides (4), and wherein the defined volume (6) is adapted to contains a heated treatment medium which is lighter than the atmosphere and thereby will fill at least part of the defined volume (6), in use, and adapted to contains food products (2) in use, which are heat treated, and wherein in use there is a distance H between the lower rim (7) of the sides (4) and a transition (24) between atmosphere and treatment medium, and wherein a thermosensor (23) is provided at the transition (24) for determining the transition (24) and thereby the distance (H). The size of H is determined relative to β and the diameter of the smallest possible circumscribed circle (13) of the sides (4) in a horizontal plane for the lower rim (7) of the treatment bell (3), wherein β is the maximum allowable heeling angle of a vessel on which the processing system is installed and driven. Further disclosed is a method of controlling a processing system (1) comprising a steam bell, characterized in that the steam bell is supplied with steam until a predetermined filling degree, wherein an area between a lowermost rim (7) of the steam bell (3), in which there is access to the atmosphere, and the predetermined filling degree is kept free from steam filling, so that the steam bell is rotatable through a certain angle relative to horizontal without the steam running out below the lowermost rim thereof, a signal processor (44) with one or more inputs and one or more outputs being used for controlling the filling degree.

Inventors:
KORGAARD, Poul Erik (Møllevej 14, 9530 Støvring, 9530, DK)
Application Number:
DK2017/050256
Publication Date:
February 15, 2018
Filing Date:
August 02, 2017
Export Citation:
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Assignee:
CT INTERNATIONAL A/S (Dalsagervej 18, 9850 Hirtshals, 9850, DK)
International Classes:
A23L3/18; A21B1/48; A23B4/005; A47J27/16
Domestic Patent References:
WO2000064284A12000-11-02
WO1997038594A11997-10-23
Foreign References:
US20040159245A12004-08-19
US5072663A1991-12-17
US4966072A1990-10-30
Attorney, Agent or Firm:
PATENT NORD APS (Julius Posselts Vej 123th, 9400 Nørresundby, 9400, DK)
Download PDF:
Claims:
PATENT CLAIMS

A processing system (1 ) adapted for the heat treatment of food products (2), wherein a treatment bell (3) is provided with sides (4) and a top (5) which together define a volume (6) from the atmosphere, wherein there is an open connection (8) to the atmosphere below a lower rim (7) of the sides (4), and wherein the defined volume (6) is adapted to contain a heated treatment medium which is lighter than the atmosphere and thereby will fill at least part of the defined volume (6) in use and adapted to contain food products (2) in use which are heat treated, and wherein, in use, there is a distance H between the lower rim (7) of the sides (4) and a transition (24) between atmosphere and treatment medium, and wherein a thermosensor (23) is provided at the transition (24) for determining the transition (24) and thereby the distance (H), characterized in that the size of H is determined relative to β and the diameter of the smallest possible circumscribed circle (13) of the sides (4) in a horizontal plane for the lower rim (7) of the treatment bell (3), wherein β is the maximum allowable heeling angle of a vessel on which the processing system is installed and driven.

A processing system according to claim 1 , characterized in that the treatment bell (3) is provided with a blockable opening (14) for supplying food products (2) in a complete batch (15) adapted for filling the treatment bell (3).

A processing system according to claim 2, characterized in that a batch (15) corresponding to the size of the defined volume (6) of the treatment bell (3) is introduced into the treatment bell (3) via a downwardly directed opening in the treatment bell (3) by mutual movement between the batch (15) and the treatment bell (3). A processing system according to claim 1 , characterized in that the system comprises a transport system (17) for continuous introduction of food products (2) and simultaneous removal of food products (2), said transport system (17) having means for: raising the products (2) upwards in the treatment bell (3), keeping the products (2) for a predetermined time in the treatment bell (3) and then removing the products (2).

A processing system according to claim 1 , characterized in that the treatment medium comprises steam, and that the processing system (1 ) has a system and an assembly for supplying steam to fill the treatment bell (3) with it to a level above a lowermost boundary (10) determined by the level of the position of the thermosensor, and has a system for injecting a cooling medium (19) to terminate the heat treatment.

A processing system according to claim 5, characterized in that the blockable opening (14) comprises the top (5), said top (5) being arranged as a lid (20) hinged to the external side of the treatment bell (3) via a rod system (21 ).

A processing system according to claim 6, characterized in that a vertical rail (22) for controlling a batch (15) of food products (2) arriving from above is provided along two opposed inner sides of the treatment bell (3).

A processing system according to claim 5, characterized in that the thermosensor (23) is provided at an adjustable distance above the lower rim (7).

A method of controlling a processing system (1 ) comprising a steam bell, characterized in that the steam bell is supplied with steam until a predetermined filling degree, wherein an area between a lowermost rim (7) of the steam bell (3), in which there is access to the atmosphere, and the predetermined filling degree is kept free from steam filling, so that the steam bell is rotatable through a certain angle relative to horizontal without the steam running out below the lowermost rim thereof, a signal processor (44) with one or more inputs and one or more outputs being used for controlling the filling degree.

Description:
A PROCESSING SYSTEM FOR THE HEAT TREATMENT OF FOOD PRODUCTS AS WELL AS A METHOD OF CONTROLLING A PROCESSING SYSTEM COMPRISING A STEAM BELL The invention relates to a processing system adapted for the heat treatment of food products, wherein a treatment bell is provided with sides and a top which together define a volume from the atmosphere, wherein there is an open connection to the atmosphere below a lower rim of the sides, and wherein the defined volume is adapted to contain a heated treatment medium which is lighter than the atmosphere and thereby fills at least part of the defined volume.

A system of this type is known e.g. from US4966072. This document shows how food products are brought into such a treatment bell and are heat treated.

The processing system in the US document, however, is not suitable for use on e.g. modern fishing vessels, when these experience sea disturbances in navigation, as, because of buoyancy, the treatment medium will always have a lower boundary which is horizontal, and when the ship heels e.g. 30 degrees, the lower boundary relative to the atmosphere inside the bell will also have an angle relative to the lower rim of the bell of 30 degrees. This means that the parts of the product or products which are present in the bell, and which, during heeling, are lowest for a period each time the ship heels, will be exposed and not surrounded by the treatment medium. This involves the risk that the occasionally exposed food products do not receive sufficient heat or other desirable impact, so that they are liable to be further processed in e.g. a semi-raw or completely raw state. At the same time, some of the treatment medium will penetrate down along the inner side of the bell at the opposite side, which is naturally highest during the heeling, and run out below the open lower rim of the bell. The escaped treatment medium may be a serious problem, since, in case of heat treatment of e.g. crayfish or other shellfish, it may contain high concentrations of allergens which may make the crew operating the system very seriously ill.

The known processing system has an area of an extent H in a vertical direction between the lower rim of the sides and a lower boundary for the presence of food products, which area accommodates a thermosensor for determining the level of the transition between atmosphere and treatment medium. This area may now be filled completely or partly with treatment medium, however, the lowermost horizontal lower boundary to the atmosphere of the treatment medium is still spaced in a vertical direction from the lower rim of the bell in the entire circumference of the bell. This makes it possible to allow the bell to heel together with the ship, without treatment medium running out below a lower rim of the bell, or without food products arranged in the bell being exposed and being disposed outside a lower rim of the treatment medium. It should be noted that the distance from the lowermost horizontal boundary to the atmosphere of the treatment medium and to the lower rim of the bell may very well be quite small or close to zero, but this requires that treatment medium escaping from the bell during the possible heeling of the ship is collected effectively by a strong hood. The position of the thermosensor indicates the level of the transition between the treatment medium and the atmosphere. An appropriate determination of the size of H is not stated in the prior art.

Accordingly, an object of the invention is to provide a processing system without the above-mentioned drawbacks and also as an alternative to previously known systems. The unique aspect of the invention is that the relation between the maximum heeling angle of the ship and the size of the bell, given by the diameter of the smallest possible circumscribed circle in a horizontal plane within which the walls of the bell may be disposed, gives the geometric expression of the smallest size of H within which the system can operate without any treatment medium penetrating out below the lower rim of the sides of the treatment bell during heeling of the ship. The requirement is here that there is a connection to the atmosphere via the entire lower rim. If parts of the lower rim are closed and e.g. firmly connected with a bottom, it will be the longest rectilinear distance in a horizontal plane between the opening to the atmosphere and a wall which is decisive for the maximum heeling angle. This simple relation may correspondingly be applied for determining a maximum filling degree of the treatment bell during treatment, without any exposure of the lower parts of the food products. Alternatively, the treatment bell and the system are fixed non-adjustable units, where the system is then forced to be out of operation when the heelings of the ship exceed a given value.

Usually, the opening or openings of the treatment bell along a lower rim thereof will be provided in the directions where the ship heels least. For ordinary fishing vessels, this means that these openings are provided along the side or the sides of the bell which face toward the front or the rear end of the ship, given by the direction of the heading of the ship, so that the bell does not have any openings along the sides facing toward starboard or port. The reason is that the lateral rollings of the ship will frequently be greater than rollings perpendicular to the longitudinal axis.

When working with complete batches, where a group of food products, which together precisely fill the treatment bell, is collected and then conveyed collectively into and out of the bell, this may expediently take place via a blockable opening in the bell. This may e.g. be via a lid at the top or via a side panel. Expediently, it is the batch of food products which is moved into a stationary bell either from above or from the side, but, in practice, it will also be possible to allow the batch to be immovable relative to the deck or the floor, and then allow the bell to be the movable part.

Introduction of a complete batch via an open bottom of the bell is also a possibility, where batch and bell are then moved mutually vertically until the bell surrounds the batch and may subsequently be filled with the hot treatment medium. Again, there must be clearance from the lowermost rim of the bell and up to the batch, so that the bell with the batch in it, when following the movements of a ship in the sea, ensures that no treatment medium penetrates out into the atmosphere, and also ensures that there are no parts of the batch which suddenly are not surrounded by the treatment medium during the heat treatment.

It is also possible to make a system where the food products are supplied to the bell in small units from below via a transport system, and via the transport system a minimum residence time in the treatment bell is ensured, which is filled with the treatment medium during this. With this embodiment, there must also be an area at the bottom in which no treatment medium is present, so that the bell will be able to follow the heeling of the ship without any escape of treatment medium.

It is preferred that the treatment medium comprises steam, and that the system has a system and an assembly for supplying steam to fill the treatment bell with it to a level above a lowermost boundary, as well as a system for injecting a cooling medium to terminate the heat treatment. The cooling medium may e.g. be water, which is introduced via a system of nozzles, so that all parts of the interior of the treatment bell rapidly receive an even flow of small water drops, which will be able to ensure that the steam in the bell condensates very rapidly, and, at the same time, the many drops will also result in sprinkling of the food products, so that they are subjected to a beginning cooling. When the blockable opening comprises the top, it is preferred that this is arranged as a lid hinged to the external side of the bell via a rod system. This allows it to be ensured that the lid may easily be adapted to be moved from a closed position, in which it fits tightly with the upper rim of the bell, to an open position, in which the lid hangs at the side of the bell and exposes the opening, the movement between the two positions taking place without the highest points of the lid during the closing and opening movements getting high above the uppermost rim of the bell. This is of importance on ships where the ceiling height is frequently limited.

It is an advantage if a vertical rail is established along two opposed inner sides of the bell for controlling a batch of food products arriving from above. Hereby, a batch of composite food products may be moved from above and down into the bell without getting jammed and without impinging on the inner side of the bell.

When a thermosensor is arranged at an adjustable distance from a desired boundary downwardly to the atmosphere for the steam in the treatment bell, it may be ensured that the temperature here is always higher than a predetermined minimum value. This may be done by adding more steam when a temperature below the desired minimum value is recorded. It should be noted that steam will continuously condensate on the surfaces of the food products during the heat treatment of these, and the consequently lost steam in the bell will cause the lower steam boundary to the atmosphere to move upwards, and this may be recorded via the thermosensor as a drop in temperature, and ordinary regulating technique may be used for then turning on the supply of additional steam, whereby the lower steam boundary to the atmosphere will move downwardly and reach the thermosensor, which will consequently record a temperature which is again above the desired minimum temperature in the bell during the treatment. It is ensured in this manner that the food products in the bell are subjected to a constant, uniform and known temperature throughout the process. It should be noted that the level at which the thermosensor is arranged, is adjustable in a vertical direction, so that it is possible to adjust the steam filling degree of the bell. The adjustment may take place prior to the supply to the individual ship of the system in dependence on the sea disturbance which the ship is expected to experience, or the adjustment may take place on the ship e.g. in dependence on the actual sea disturbance. It may be ensured hereby that unnecessary overfilling of the bell does not take place, when there is no significant sea disturbance. The thermosensor may optionally be mounted vertically slidably on a guideway, so that its height may easily be adjusted according to the circumstances. Alternatively, a row of thermosensors, vertically above each other, may be provided in the bell, and it will then be decided by selection of a signal from a thermosensor in the row how far below the level of the food products the steam boundary to the atmosphere should be. If such a system is coupled to a signal processor having one or more inputs and one or more outputs, it will be possible for the system to be controlled automatically.

Thus, the invention also comprises a method of controlling a processing system comprising a steam bell. According to the invention, the steam bell is supplied with steam until a predetermined filling degree, wherein an area between a lowermost rim of the steam bell, in which there is access to the atmosphere, and the predetermined filling degree is kept free from steam filling, so that the steam bell is rotatable through a certain angle relative to horizontal without the steam running out below the lowermost rim thereof, a signal processor with one or more inputs and one or more outputs being used for controlling the filling degree.

When using a thermosensor coupled to the signal processor it is possible to adjust the steam filling in the bell to the motions of a ship, thereby always ensuring that all food products heat treated in the steam bell achieve the desired core temperature, without discharging unnecessary steam out below the rim of the steam bell because of the motions of the ship.

The invention will now be explained more fully with reference to the drawings, in which:

Fig. 1 shows an embodiment of a treatment bell shown in lateral view,

Fig. 2 is a section along the line A-A in fig. 1 ,

Fig. 3 is a section along the line B-B in fig. 1 ,

Fig. 4 shows a vertical section through the treatment bell shown in fig. 1 , but perpendicular to the section shown in Fig. 2 and without a batch,

Fig. 5 shows an alternative embodiment of the invention in a sectional view corresponding to the section A - A in fig. 6,

Fig. 6 is the system shown in Fig. 5 seen from above,

Fig. 7 shows the processing system with a considerable heeling angle relative to horizontal,

Fig. 8 shows details belonging to Fig. 5,

Fig. 9 shows a lattice box for use in the system shown in figs. 5 and 6, Fig. 10 shows the thermoelement and a mounting rail for it,

Fig. 1 1 is the control system of the system shown in schematic form, and

Fig. 12 is a schematic representation of the processing system onboard a ship.

A processing system 1 according to the invention is shown from the side in fig. 1 , and the system comprises a treatment bell 3 (hereinafter called bell 3 for convenience) with sides 4 and a top 5, and, as will be seen in the horizontal sectional view in fig. 3 along the line B-B in fig. 1 , the bell 3 is four-sided in this embodiment, and thus has four sides 4, and, as will be seen here, the sides 4 are essentially of the same length. The treatment bell 3 may have more sides or be round. When the term "bell" is used here, it is because the treatment space at the bottom always has an open connection 8 to the atmosphere at at least a portion of a lower rim 7 of one or more sides 4. The lower rim 7 indicates the level of the upper limit 25 for the access of the treatment medium to the atmosphere with the processing system arranged in a horizontal position, and this level is indicated by the line 25 in fig. 2. The bell 3 also comprises a top 5, as will be seen in fig. 1 . Together, the top 5 and the sides 4 define a volume 6, which may contain a gas (not shown) which is lighter than the atmosphere, and the gas will always have a horizontal boundary 24 to the rest of the atmosphere because of the buoyancy. The boundary 24 is shown here as a dashed straight line, but, in reality, the boundary will most frequently be more diffuse, and it may also be uneven because of circulation in the gas.

The actual space in the bell 3 in which the treatment takes place, is called the treatment space 10, and this space is downwardly limited a distance H, indicated by the arrow 1 1 , above the lower rim 7, and, as will be seen in fig. 2, the space may be filled with a batch 15 of food products, which in this case rests on a ledge 26. H is a quantity which may be changed according to the sea disturbance which a ship is to experience or actually experiences. H cannot be greater than the distance from the lower rim 7 and up to the ledge 26. The greatest sea disturbance may be tolerated, if H is in the area halfway between the ledge 26 and the lowermost rim 7 of the bell 3. If there is no sea disturbance, H may range from the lower rim 7 and up to the ledge 26, and the boundary 24 between the treatment medium and the atmosphere will then be right below the ledge 26. It is noted that the lower rim 7 extends along one of the sides 4 in the four-sided bell shown, and that the other sides are built together with a bottom of the bell. The rim 7 and the open connection 8 to the surroundings are expediently arranged to point in the longitudinal direction of the ship, so that it faces toward the stem or the rear end of the ship, as this ensures least possible overflow beyond the rim 7, since the heelings of the ship are typically greater about the longitudinal axis than about an axis perpendicular thereto.

In the case shown, the batch 15 is formed by a plurality of wire baskets 27 filled with food products, of which a single one 2 is shown schematically in figs. 2, 3 and 7, so that the treatment medium can easily penetrate into and surround each individual one of the food products 2 stacked in the wire baskets 27. The wire baskets 27 are suspended from a yoke, so that the complete batch may be lifted out of and into the bell 3 via the yoke. The wire baskets 27 are provided with a closure, so that the food products are surrounded completely and may be stacked for the filling of each wire basket, without any risk that they drop out of the wire baskets during the heat treatment and the subsequent cooling and freezing. After freezing, the food products may be taken out of the wire baskets and be finally packaged, following which the wire baskets are returned for renewed filling with food products, such as parts of crayfish or entire shellfish, such as e.g. shrimps.

The lower boundary 24 of the gas is thus disposed between the upper limit 25 for the open connection 8 to the surroundings and the part of the bell 3 which is filled with a batch for treatment. Fig. 7 shows how the limit 24 between the atmosphere and the treatment medium remains horizontal even if the vessel heels strongly, here indicated as the angle β between horizontal and the actual heel of the ship. As will appear, this heel exposes a portion of a wire basket 27, and the food products in it will now not receive the heat treatment which is necessary. It will also be seen that the treatment medium at the opposite side reaches down below the level of the upper limit 25 for the open connection 8 to the surroundings, and, consequently, the gas will run out here. To catch any outflowing gas or treatment medium, a hood 28 will be arranged at the lower open connection 8 to the surroundings, said hood ensuring that escaped gas does not cause trouble to the crew.

In this case, the blockable opening 14 in the bell 3 is formed by a lid 20 disposed at the top 5 of the bell 3. But sides 4 may also constitute such an opening. Finally, it is possible to fill the bell with a batch via the bottom and allow the bottom to be completely open. During filling, the batch 15 and the bell 3 are moved relative to each other for positioning the batch at the top of the bell. If, in particular, the bell 3 is filled from below, it makes sense that the batch is immovable, while it is the bell which is lowered down over it. But in case of filling from side and top, it will typically be the batch which is lifted or moved down/into the bell. Then, the blockable opening 14 may be closed and blocked, following which the treatment is started.

Figs. 3 and 4 show a pipe system or assembly 18 for supplying steam, which is the most common gas used for heat treatments of shellfish with a gaseous medium. The steam is fed into the bell 3, in which it is distributed to a distributor pipe 30 having a large number of holes in each side, so that the steam may be caused to rapidly fill the treatment space 10 in the bell.

A coolant, in this case water, may be added via a plurality of nozzles, which, here too, are located along one or more vertically extending nozzle pipes 31 inside the bell. Hereby, it is possible to sprinkle the entire batch at the same time, so that the steam is beaten down everywhere in the bell 3, and the food products are cooled on their surfaces, so that, following transport out of the bell, they do not emit steam because of a high surface temperature.

As will be seen in fig. 4 and fig. 3, a vertical rail 22 is present along two opposed sides 4 in the bell 3, which rail is adapted to guide the batch 15 when this e.g. lowered down into the bell 3 from above. The rail 22 ensures that the batch 15 gets correctly down into and up from the bell again after completed treatment, said batch 15 being typically hoisted and lowered by a hoist or a winch from an overlying beam (not shown).

Fig. 4 shows a thermosensor 23 mounted on a vertical guideway 29, so that its position may be adjusted up and down. Optionally, an actuator (not shown) may be provided, so that the position may be adjusted from the outside. Several thermosensors may be provided in the bell to monitor the process with a view to quality control and in order to control the level of the boundary between the treatment medium and the atmosphere.

The lid 20 is hinged to the side of the bell 3 via a rod system 21 , so that the lid may be moved by an actuator 33 from a closed position, as shown in fig. 1 , to a position (not shown) in which it is seated down along the side of the bell. The rod system with a short rod and a long rod ensures that the movement takes place without the uppermost point of the lid getting above ceiling height in the ship.

Fig. 5 and fig. 6 show how a treatment bell according to the invention may be adapted for continuous operation, where small batches or portions enclosed in lattice boxes 32 are arranged on a transport system 17, which transports the lattice boxes 32 below the bell 3 and then upwards inside the bell, and subsequently downwards and out below the lower rim 7 of the bell. This method and associated processing system, when used on a ship, also require that at the transition 24 between the treatment medium, usually steam, and the atmosphere there is an area which is surrounded by the bell along all sides, so that the steam does not readily flow out below the rim 7 of the bell at the same moment as the ship heels. Suitable use of regulating technique and thermosensors will allow the area below the transition 24 to be regulated relative to the actual sea disturbance of the ship, but, of course, the residence time in the hot steam must be ensured, e.g. by adjusting the speed of the transport system 17. It is also possible to arrange a buffer of portions (not shown) within the topmost area of the bell, so that the residence time in the buffer zone is always a certain minimum. Hereby, the system runs with the same speed of the transport system 17 and the same level of the transition 24 irrespective of the sea disturbance, if only this does not exceed what is the prescribed maximum heeling angle β. Such a system, too, will need a hood (not shown) capable of absorbing any escaped steam along the rim 7.

Fig. 8 shows the section C from fig. 5 on an enlarged scale, and the thermosensor 23 is visible here. Fig. 10 also shows an enlarged representation of the guideway 29 and the bracket 34 coupling the thermosensor 23 to the guideway 29 in an adjustable manner. This arrangement makes it possible, merely by loosening a single nut 35, to adjust the height above the lower rim 25 at which the thermosensor is to be disposed. Fig. 9 shows a 3d representation of the lattice box 32 shown in fig. 6 and fig. 5 to be mounted on the transport system 17. This system comprises two chains 40, which are arranged in parallel, and which are run over a plurality of chain wheels, said chains 40 defining between them a free space which allows lattice boxes 32 to be suspended from the chains 40. Hereby, a traditional paternoster system may be constructed, so that the lattice boxes 32 are transported vertically up into the steam bell 3, are moved a horizontal distance and are finally moved vertically downwards again to be transported out below the rim 25 of the bell 3. During the transport up into and down from the steam bell, the lattice boxes will be moved through the area of the height H given by the arrow 1 1 in fig. 5, in which there is no hot steam, as the thermosensor 23 determines the level 24 of the transition between steam and atmosphere. In many ways, the lattice box 32 shown in fig. 9 is similar to the previously mentioned wire basket 27, but has a slightly difference size and comprises two oppositely arranged suspension brackets 37, which allow the lattice box to be hooked between the chains 40 so that they are pivotally mounted here. The suspension brackets 37 are arranged above the centre of gravity of the lattice boxes 32, so that the boxes automatically maintain the same orientation during the transport up into and downwards out the steam bell. A suitable gap is ensured between the boxes 32 on the chain 40, so that the boxes may freely rotate about the suspension bracket 37 at any time without colliding with each other.

The bell 3 may be closed along two of the sides 4, viz. the sides facing toward the starboard and port sides of the ship. This appears from fig. 12, in which the outline of the central section and the stem 42 of the fishing vessel 36 are shown. Fig. 12 also shows a complete treatment system comprising a steam bell 3 and a subsequent cooling system 38, which ensures that the cooling takes place rapidly and effectively after the steam boiling. In the example shown, the transport system 17 extends through the steam bell 3 as well as the subsequent cooling system 38. At each of the closed sides toward port and starboard, where the lower rim of the bell is extended downwards, e.g. down to the floor of the ship, no steam can escape when the ship rolls from side to side. An operator 41 is shown in position for applying filled lattice boxes to the chains 40. As shown in fig. 6, service doors 39 are provided in the side of the bell facing towards starboard and port, and in fig. 6 the service door toward starboard is shown in an open position. If unforeseen events should take place inside the steam bell, e.g. a lattice box is disengaged from the chain 40, it is easy for the crew to get access to the interior of the bell and to repair the damage. Fig. 1 1 shows a sketch of a steam boiling system 1 , where the control system for it is shown. This comprises a PLC 43 or a similar computer, which comprises or is connected to a PID regulator 44, whose input signal also comprises the signal 45 from the thermosensor 23 in the steam bell 3. The computer and the PID regulator constitute at least a signal processor. The PID regulator 44 converts the thermosensor signal 45 into a power signal 46 in the range 0 to 20 mA, which is applied to an I - P converter 47 in which the power signal 46 is converted linearly into a pressure signal 51 in the range 0 to 1 bar via input from an ordinary compressed air source 48 of not below 1 .4 bars. The pressure signal 51 is used for adjusting the position in one or more proportional valves 49, which have a steam source 50 on the input side and is connected with the steam distributor pipe 30 of the steam bell on the output side. Adjustment of the position of the thermosensor above the lowermost rim of the steam bell and setting of the time constants of the PID regulator result in a very precise control of the impact of the steam on the food products during the residence in the steam bell, no matter whether a continuously operating system or a batch system is involved.

Reference numerals

I Processing system

2 Food products

3 Treatment bell

4 Sides

5 Top

6 Volume

7 Lower rim

8 Open connection

9 Defined volume

10 Lower boundary of the treatment medium

I I Extent H

12 Heeling angle β

13 Circumscribed circle

14 Blockable opening

15 Batch

16 Downwardly directed opening

17 Transport system

18 Assembly for supplying steam

19 System for injecting cooling medium

20 Lid

21 Rod system

22 Vertical rail

23 Thermosensor

24 Boundary

25 Level of upper limit of open connection

26 Ledge

27 Wire basket

28 Hood Vertical guideway

Steam distributor pipe

Nozzle pipe

Lattice box

Actuator

Bracket

Nut

Outline of fishing vessel

Suspension bracket

Cooling system

Service doors

Chains

Operator

Stem of fishing vessel

PLC or similar computer

PID regulator and signal processor Signal from thermosensor

Power signal in the range 0 to 20 mA l-P converter

Compressed air source

Proportional valve

Steam source

Pressure signal