WO1987006811A1

WO1987006811A1 - Apparatus for boiling a product such as shrimps

Info

Publication number: WO1987006811A1
Application number: PCT/NL1986/000014
Authority: WO
Inventors: Douwe Venema
Original assignee: Euro Technical Oilservices B.V.
Priority date: 1986-05-16
Filing date: 1986-05-16
Publication date: 1987-11-19
Also published as: EP0267185A1

Abstract

An apparatus for boiling a product such as shrimps comprising a reservoir for liquid used for boiling and heat supply means for supplying heat to the boiling liquid, whereby the reservoir comprises a conveyor device that transports the product through the boiling liquid. In a preferred embodiment the conveyor device comprises a perforated conveyor belt having upright division plates at regular intervals. The device preferably comprises further means for cooling the product in the same device after boiling.

Description

APPARATUS FOR BOILING A PRODUCT SUCH AS SHRIMPS

The invention relates to an apparatus for boiling a product such as shrimps comprising a reservoir for liquid used for boiling and heat supply means for supplying heat to the liquid to be used for boiling. As is known, such a device is used on board shrimp fishing boats for boiling shrimps. The shrimps are sorted from the catch and then put into a cooker. Beneath this cooker is a burner which keeps the water used as boiling liquid at temperature. The temperature of the water is lowered by putting the shrimps in the cooker, so that the burner has to be fired at a high rate to counteract this fall in temperature in as short a time as possible. A lot of fuel is used as a result. Furthermore the burner must also be kept in operation during the time that there are no shrimps in the cooker, so that the boiling device remains -ready for operation. Fuel costs are therefore relatively high. In addition, because of the temperature fall when the shrimps are placed in the cooker, it is uncertain whether the shrimps are kept at the correct temperature for a sufficiently long time. The purpose of the invention is to provide a device of the type described in the preamble with which a product such as shrimps can be boiled in a more efficient way with respect to operational reliability and heat technology. According to the invention this aim is achieved because the reservoir comprises a conveyor device that transports the product through the liquid used for boiling. By guiding the product through the boiling liquid continuously instead of in batches it can be ensured simply that the product always remains in the boiling liquid long enough at boiling temperature so that the boiled product satisfies the requirements made in that respect. The product transit can be be related simply to the supply of heat, so that the liquid used for boiling is kept constantly at boiling temperature. By guiding the product in a continuous flow through the liquid used for boiling, no fall in temperature occurs as a result of sudden large quantities being fed in, so that the heat supply can be regulated very efficiently.

A favourable embodiment of the device is obtained if the boiling reservoir has an elongate form and the conveyor device comprises a perforated conveyor belt which is provided with upright division plates at regular intervals, whereby the conveyor belt is guided by at least two guide rollers which are arranged lengthwise at both ends of the reservoir such that a lower part of the belt extends at a distance from the reservoir bottom corresponding to the height of the division plates, and whereby the conveyor device further comprises drive means for rotary driving of a guide roller and a dosage supply device for feeding in the product beneath the lower part of the conveyor belt. The lower part of the conveyor belt comprises compartments each between two adjacent division plates and formed in combination with the reservoir bottom and side walls of the reservoir, in which compartments the shrimps are confined and transported. The shrimps are thus kept underwater and kept moving well, so that the boiling process proceeds predictably.

A simple discharge of the boiled product out of the boiling device is obtained when according to the invention the reservoir bottom close to the foremost guide roller in the direction of movement of the lower conveyor belt part runs inclining upwards for a distance and that a third guide roller is arranged which guides the conveyor belt parallel to this bottom part and up to a higher level. The conveyor belt carries the boiled shrimps along up to the end of the upward running bottom, after which the shrimps are discharged, for example via a hopper.

If the dosage supply device is coupled for driving with the drive means for the conveyor belt and the drive means comprise drive speed regulating means, the transit speed can be set to correspond with the supply of heat and with the period the product is required to remain in the liquid used for boiling. A further favourable development of the invention is obtained when the conveyor belt has a form such that it can carry the product from beneath the lower part of the conveyor belt up onto the upper part, that cooling means are arranged close to the upper conveyor belt part and that on the side of the device close to the supply device are arranged discharge means for discharging cooled product from the upper part. After boiling the shrimps are carried to the upper part of the conveyor belt, where they are cooled by the cooling means to a suitably low temperature ' of at most several degrees above zero. This is favourable in view of the fact that it has been found that_ the shrimps become easily contaminated with bacteria which thrive best at a temperature of around 10°. By cooling the shrimps to_# near freezing point these bacteria cannot multiply, so that the degree of contamination with bacteria remains below an acceptable minimum.

If the upright division plate slope forward in the conveying¹ direction the product is carried around the guide rollers in a reliable manner during movement. The cooling of the boiled shrimps can take place in a suitable manner using sea-water. In accordance with a further development of the invention this sea-water is thereby first heated in a first heat exchanger to a temperature close to boiling point, and then cooled to the required cooling temperature. In this way the cooling water becomes virtually or wholly germ-free, so that the finally boiled and cooled product has a low germ count.

The cooling of the heated sea-water can be carried out in two phases, whereby in the first phase the heated water is cooled with sea-water and in the second phase with cooling fluid from a cooling device. The heat supply means can comprise in the known manner a burner system, but a further improvement of the invention is achieved if the heat supply means comprise a heat interchange device which on the one hand makes heat interchanging contact with a waste heat source and on the other with the liquid used for boiling, while a conveyor device is arranged which transports the product through the liquid used for boiling. Although the use of waste heat with a relatively low temperature appears at first sight to be unfavourable for supplying sufficient heat to allow the boiling process to proceed properly, the boiling process can in fact be very well controlled by guiding the product in a continuous flow through the liquid used for boiling. In an application for the shrimp fishing industry a favourable embodiment of the device according to the invention is obtained because the heat interchange device comprises a circuit of a heat transfer fluid, in which circuit are located a first heat exchanger of a waste heat boiler of a combustion engine, a second heat exchanger on the boiling reservoir and a circulation pump. Fishing for shrimps is carried out with trawl nets, that is, while the fishing boat is in motion. The combustion engine of the boat is therefore in operation. As is known, a comparatively large amount of waste heat is released in a combustion engine and the exhaust gases still have a temperature lying above the boiling temperature of water, so that the waste heat from the exhaust gases can be used for the application of the invention.

In this respect a very safe device is obtained if the heat transfer fluid is a thermal oil. The temperatures occurring are such that, in contrast to steam, thermal oil can be used virtually without pressure. The device according to the invention remains simple as a result and does not have to be inspected for the strict requirements applicable to steam.

The device according to the invention can be brought to temperature rapidly and also be kept at temperature when the boat is at standstill, if according to the invention an auxiliary burner is arranged in the waste heat boiler.

The invention will be elucidated further in the following description with reference to several embodi ents. Fig. 1 shows a schematic longitudinal section of a boiling device according to the invention.

Fig. 2 shows another embodiment of the device according to the invention.

Fig. 3 is a diagram of the heat supply for a device according to the invention.

Fig. 4 shows a schematic section of a waste heat boiler as applied in the device of fig. 3. ^•

The device shown in fig. 1 for boiling shrimps comprises a reservoir 2 of which the actual boiling reservoir 25 is in elongate form. Arranged in reservoir 25 is a perforated conveyor belt 26 which is provided at regular intervals with upright division plates 27. The conveyor belt is arranged round guide rollers 28, 29 and 30 such that the lower part of the conveyor belt extends at a" distance from the reservoir bottom 31 corresponding with the height of division plates 27. In this way the conveyor belt 26 with the plates 27 and the reservoir bottom 31 bounds a number of compartments 41 into which the shrimps for boiling are transported, in a manner to be described later, through the liquid used for boiling 33. The boiling reservoir 2 further comprises drive means not further indicated which grip onto a guide roller to move the conveyor belt 26 in the direction of the arrow.

Also fitted is a supply device 37 which comprises a funnel 38 on the underside of which is located a rotating sluice 39. The sluice is coupled to the guide roller 28 by means of the chain 40 indicated with dotted line's, so that the rotation speed of sluice 39 corresponds with the speed of movement of conveyor belt 26. When the device is operational the shrimps are thus fed in doses through the supply device 37 such that these shrimps are carried beneath conveyor belt 26. Heat is supplied to the water used for boiling in reservoir 25 using a heat transfer fluid that circulates in a circuit to be described further with reference to fig. 3. For this purpose the reservoir 25 is provided with a double bottom functioning as heat exchanger 18. The heat transfer fluid is fed on one side via the feed pipe 34 and carried away on the other side via the discharge pipe 35. Via the bottom 31 of the reservoir the liquid used for boiling 33 is thus in heat exchanging contact with the heat transfer fluid and is kept at temperature as a result.

The shrimps fed in by the supply device 37 beneath the lower part of conveyor belt 26 are transported, while being confined in the compartments 41, to the right as seen in fig. 1. Because the compartments 41 are closed off at the top by the conveyor belt 26 the shrimps are held submerged by the device during the whole of the transport. Close to the guide roller 29 the reservoir bottom 31 has a rising portion 32. Guide roller 30 is arranged such that the part of the conveyor belt 26 extending between roller 29 and roller 30 runs parallel to this bottom portion 32. The guide roller 30 is moreover fitted higher than the upper edge of bottom portion 32 so that the boiled shrimps are moved upwards with the said portion of the conveyor belt and are moved over the edge of the bottom 32 into the shrimp discharge 36. The drive means comprise drive speed regulating means with which the speed of the conveyor belt is adjusted to the heat supply, and moreover such that the shrimps remain for a sufficiently long time in the liquid used for boiling 33. This means in practice that the shrimps remain in the boiling water for about four minutes. In the device 70 in fig. 2 the division plates 72 of conveyor belt 71 incline forward in the conveying direction indicated by arrow 73. The shrimps are fed via the supply 86 on the right-hand side of device 70 to the underside of the conveyor belt, where they are boiled in the same way as with the device of fig. 1. Because of their sloping position the division plates carr.y the shrimps upward on - 1 -

the left-hand side of the device as far as the upper part of the conveyor belt. Above this uppermost part is arranged a spray line 74, through which cooling water is sprayed onto the shrimps. Placed underneath the conveyor belt is a receiving bin 75 which leads to a discharge 76. This bin is preferably insulated to prevent undesirable loss of heat from the water used for boiling. Also arranged on the right-hand side of device 70 is the shrimp discharge 77, via which the boiled and cooled shrimps from the upper conveyor belt part are discharged out of the device into a holder placed below discharge 77, this holder preferably being an insulated cool box 81. By accommodating them in a cool box 81, the cooled shrimps remain well at the desired low temperature. In the device 70 the water used for boiling is heated using a separate burner 79 which emerges into a burner space 78 arranged below the reservoir. The flue gases from burner 79 are_β guided through the double bottom of the reservoir. The cooling water sprayed through the spray pipe 74 consists of treated sea-water. This sea-water is, as is shown diagrammatically, pumped up using the pump 82. A part of the pumped up water is guided via a cyclone 83. Because many bacteria attach themselves to solid particles, a large part of the bacteria will disappear via the overflow of the cyclone. The cleaned sea-water is carried via a first stage of heat exchanger 84 to heat exchanger 80 in the flue gas duct of the burner space 78. The sea-water becomes virtually germ-free through the heating. The heated sea-water is returned through the first stage of heat exchanger 84 where it is cooled, flowing together with water supplied from the cyclone.. In the second stage of the heat exchanger 84 the water is cooled further using sea-water. In the third stage of the heat exchanger the cooling water is brought finally to the desired low temperature of around freezing point, using a cooling device 85. The thermal control shown schematically in fig. 2 is one of a number of possibilities. So for example a waste heat boiler or a boiler provided with a separate burner can be used instead of heat exchanger 80. In addition the used cooling water carried away via discharge 76 can be re-used in the second stage of heat exchanger 84 instead of sea- water.

As noted earlier the device according to the invention is particularly suitable for heating with waste heat. The waste heat source in fig. 3 is formed in the device from fig. 1 by a combustion engine 3 which is the propulsion motor of a fishing vessel in which the device 1 is set up. The motor 3 in operation produces exhaust gases which are discharged via the outlet 4. Accommodated in outlet 4 is a waste heat boiler 5 in which heat is extracted from the exhaust gases using the heat interchange device 10 already referred to.

The device 10 comprises a circuit 6 of a heat transfer fluid that is preferably thermal oil. Accommodated in the circuit 6 are a first heat exchanger 12 in the waste heat boiler 5, the already mentioned heat exchanger 18 on the boiling reservoir 2 and a circulation pump 7. Further linked to the circuit 6 are a pressure vessel 8 and a heating installation 9 not to be described further having a third heat exchanger 20 for heating purposes.

In waste heat boiler 5 thermal oil is fed to the first heat exchanger 12 through the feed pipe 13 and after heating carried away through discharge pipe 14. Accommodated in the boiler 5 are two valves 16 and 17 which can close respectively a bypass 19 and the duct in which the heat exchanger 12 is located. In the position of the valves 16 and 17 shown, hot flue gases flow via outlet pipe 4 through heat exchanger 12 and through discharge 11 to the outside. In the position of valves 16 and 17 drawn with dotted lines the flue gases can flow via bypass 19 directly to discharge 11, without passing heat exchanger 12. Valves 16 and 17 are set in this way when the boiling device is not in use, for example when the fishing vessel is sailing to the fishing grounds or is returning to port. Also when the motor load is low and the flue gas temperature is too low these flue gases are guided via bypass 19. The control of valves 16 and 17 can operate automatically according to the flue gas temperature.

Further arranged on boiler 5 is an auxiliary burner 15 which can provide the circuit 6 with heat when the motor 3 is not operational or is not producing sufficient heat. A separate central heating boiler for heating the vessel accommodation can consequently also be dispensed with.

Claims

1. Device for boiling a product such as shrimps comprising a reservoir for liquid used for boiling and heat supply means for supplying heat to said boiling liquid, characterized in that said reservoir comprises a conveyor device that transports the product through the liquid used for boiling.

2. Device as claimed in claim 1, characterized in that the boiling reservoir has an elongate form and the conveyor device comprises a perforated conveyor belt which is provided with upright division plates at regular intervals, whereby said • donveyor belt is guided by at least two guide rollers which are arranged lengthwise at both ends of said reservoir such that a lower part of said belt extends at a distance from the reservoir bottom corresponding to the height of said division plates, and whereby said conveyor device further comprises drive, means for rotary driving of a guide roller and a supply device^' for feeding in the product beneath the lower part of said conveyor belt.

3. Device as claimed in claim 2, characterized in that the reservoir bottom close to the foremost guide roller in the direction of movement of the lower conveyor belt part runs inclining upwards for a distance and that a third guide roller is arranged which guides the conveyor belt parallel to this bottom part and up to a higher level.

4. Device as claimed in claim 2 or 3, characterized in that the supply device comprises a dosing device which is coupled for driving with the drive means for the conveyor belt and that said drive means comprise drive speed regulating means.

5. Device .as claimed in claim 2 or 3, characterized in that the conveyor belt has a form such that it can carry the product from beneath the lower part of said conveyor belt up onto the upper part, that cooling means are arranged close to the upper conveyor belt part and that on the side of the device close to the supply device are arranged discharge means for discharging cooled product 5 from said upper part.

6. Device as claimed in claim 5, characterized in that the upright division plates slope forward in the conveying direction.

7. Device as claimed in claim 5 or 6, characterized in 10 that the cooling means comprise cooling water supply means.

8. Device as claimed in claim 7, characterized in that said device is placed on board a ship and that the cooling water supply means comprise a sea-water suction pump and a piping system leading to the conveyor belt, whereby located

15 in said piping system are a first heat exchanger connected to a circuit comprising a heat source and a second heat exchanger connected to a circuit comprising a cooler.

9. Device as claimed in claim 8, characterized by a third heat exchanger connected upstream of the second heat

20 exchanger and having sea-water flowing through it.

10. Device as claimed in any of the foregoing claims, characterized in that the heat supply means comprise a heat interchange device which on the one side makes heat interchanging contact with a waste heat source and on the

25 other with the liquid used for boiling, while a conveyor device is arranged which transports the product through said boiling liquid.

11. Device as claimed in claim 10, characterized in that the heat interchange device comprises a circuit of a

30 heat transfer fluid, in which circuit are located a first heat exchanger of a waste heat boiler of a combustion engine, a second heat exchanger on the boiling reservoir and a circulation pump.

12. Device as claimed in claim 11, characterized in that the heat transfer fluid is a thermal oil.

13. Device as claimed in claim 11 or 12, characterized in that an auxiliary burner is arranged in the waste heat boiler.