WO2002076856A1

WO2002076856A1 - Method and device for removing an ice/water mixture from a container via a drain

Info

Publication number: WO2002076856A1
Application number: PCT/NL2002/000200
Authority: WO
Inventors: Pieter Jellema; Jelle Luutzen Nijdam
Original assignee: Solutherm B.V.
Priority date: 2001-03-28
Filing date: 2002-03-27
Publication date: 2002-10-03
Also published as: NL1017722C2; EP1373104A1

Abstract

A method and device for removing an ice-water mixture via a drain (6) from a container (1), such as a chamber for producing an ice-water mixture under a low pressure and under cooling, wherein the ice-water mixture is guided to the drain (6) while flowing over a container wall (3), and adjacent the drain (6) water is supplied, such that an impulse is exerted on the ice-water mixture to be drained, as a result of which adjacent the drain a hydromechanical mixing is created. The supply means can comprise a sprayer (9) and a tangentially directed pipe (16) disposed in or near the drain.

Description

Title: Method and device for removing an ice -water mixture from a container via a drain

This invention relates to a method for removing an ice-water mixture via a drain from a container, such as a chamber for producing an ice-water mixture under a low pressure and whilst cooling, wherein the ice-water mixture in the container is stirred, as known from NL-C- 1006921. An ice-water mixture can be produced by supplying water to a, for instance tubular, chamber in which such a low pressure and temperature prevail that water is evaporated and freezes onto a cold surface placed in the chamber, while through the evaporation heat is abstracted from the non-evaporated water, which is thereby converted into an ice-water mixture. In such a method as known from US-A-4,845,954, use is made of a chamber having a water bath, from which the ice-water mixture is drained via an overflow. In such a method as known from WO-A-00/37865, use is made of an inclined gutter extending in the longitudinal direction of the vessel and having a drain at the lower end. A problem in producing an ice-water mixture in such a manner is that ice accretion onto the wall may occur, as a result of which the drain may get clogged. To mitigate this problem, it may be elected, as known from the NL-C-1006921 mentioned in the opening paragraph hereof, to place the drain under a water surface. As a consequence, a higher pressure prevails at the drain than on the boihng water surface. Due to the higher pressure, boiling phenomena adjacent the drain, and hence freezing of the drain, will be prevented. However, this solution at the same time means that the speeds in the water bath created will be relatively low, as a result of which ice separation may occur after all, due to the lower mass density of the ice. As the separated ice may proceed to work like a sieve for the ice-water mixture, as a result of which only water is passed, the discharge of ice from the container may stagnate after all. This problem can be solved by the use of a mechanical stirring apparatus which prevents the formation of an ice sieve. Such a stirring apparatus, however, is provided with a shaft lead-through to the surroundings, which may lead to leakage of air to the vacuum space, which is disastrous to the production process for forming the ice- water mixture. The object of the invention is to provide a method with which adjacent the drain freezing can be prevented and remedied without necessitating the provision of moving parts that require a lead-through to the surroundings that is to be sealed.

According to the invention, this is achieved in a method of the type described in the opening paragraph hereof if the ice-water mixture is guided to the drain whilst flowing over a container wall, and adjacent the drain water is supplied in such a manner that an impulse is exerted on the ice- water mixture to be drained, so that at the drain a hydromechanical mixing is created. Through these measures, on the one hand, the formation of an ice sieve is prevented in an effective manner and, on the other hand, ice deposit being formed or having been formed can be prevented or remedied in an effective manner by the impulse exerted via the fluid and/or by influencing the temperature of the medium supphed.

An effective impulse can be exerted on the ice-water mixture to be drained if, according to a preferred mode of the invention, the water is supplied via at least one sprayer above the drain. As a result, the ice-water mixture can be held in motion and be pushed into the drain. Alternatively, or additionally, it is possible, according to a further embodiment of the invention, that the water is supplied in the form of a jet into or at the drain, it being then particularly preferred that the jet is supphed while directed tangentially to the drain. Thus, a turbulent mixing can be accomplished with a cyclone effect in the drain, so that the ice, lighter compared with the water, is urged away from the wall of the drain, which further reduces the risk of freezing on. Another aspect concerns boiling phenomena occurring in a process under low pressure. The relatively thin water vapor that is being formed should be discharged optimally with minimal flow resistance. This too is promoted by the cyclone action, because the mass density of vapor is still lower than that of ice, so that centrally in the drain an upward vapor discharge is created. Without cyclone action, the vapor flow would have to move through a swirling mass, with all the concomitant loss of flow.

Through the supply of water, which is understood to include water with additives, such as a nucleating agent in the form of, for instance, 5% NaCl, the process of producing an ice-water mixture will be disturbed the least. By thus supplying water, not only ice formation adjacent the drain can be prevented, but what can also be accomplished, by suitably arranging sprayers, is that local drying up will not occur anywhere in the device, which advantage is evident in particular if within the container relatively thin water films for forming the ice-water mixture are used, as is the case, for instance, in a method and device according to the non-prepublished Dutch patent application 1014202, also in applicant's name.

For the purpose of creating a turbulent environment at the drain whilst disturbing the production process to the least possible extent, it is preferred, according to a further mode of the invention, that water be used in the form of an ice-water mixture. This ice-water mixture can then be drawn, for instance, from the drained ice-water mixture and be recirculated. The production process and the production capacity are then affected to the least possible extent. However, for instance for preventing or remedying ice deposits, it may be desirable that water having a temperature above the freezing point of the ice-water mixture be supplied. Here, one could think, for instance, of water coming from the supply to the container, hence water having a slightly higher temperature which is yet to be converted to an ice-water mixture through evaporation and cooling. Naturally, it is also possible, depending on the desired effect, to supply water having a temperature near the freezing point of the ice-water mixture or water having a higher temperature. Further, depending on the specific need, it is also possible to use water having a different temperature by mixing supplied and drained water or coming from a different place, this last, of course, also applying to supplied water having a temperature near the freezing point of the ice-water mixture.

The invention further relates to a device for removing an ice-water mixture via a drain from a container, such as a chamber for producing an ice-water mixture under low pressure and under cooling, in which container stirring means are accommodated, which device is characterized, according to the invention, by stirring means in the form of water supply means disposed adjacent the drain. Here, one may primarily think of at least one sprayer placed directly above the drain, but it is also possible to arrange sprayers disposed above the drain at a distance therefrom, with a view to preventing drying up of any part of the guide surfaces present in the container for forming an ice-water mixture by having water flow over them.

Alternatively, or additionally, in accordance with the invention, it may be provided that the water supply means comprise at least one pipe terminating in or adjacent the drain, which pipe can serve to generate a cyclone effect, in addition to an impulse effect.

Effective prevention of clogging at the drain with the least possible disturbance of the production process can be accomplished in accordance with a further embodiment of the invention if the water supply means in the form of a sprayer or a pipe are connected, remote from the drain, with a drain conduit connected to the drain. Thus, through recirculation, clogging can be prevented without essentially affecting the temperature of the ice-water mixture. If it is to be preventively ensured that no ice deposition occurs within the container on the surfaces susceptible thereto, or if ice deposits being formed or having been formed are to be removed, then this can be realized according to a further embodiment of the invention if the water supply means in the form of a sprayer or a pipe are connected with a supply conduit leading to the container, for water to be transformed into an ice-water mixture. Naturally, it is also possible, depending on the desired effect, to connect the water supply means the one time with a source with water having a temperature near the freezing point of the ice-water mixture and the other time with a source with water having a higher temperature, or in a desired mixed ratio of the two.

Referring to embodiments schematically represented in the drawing, the method and device according to the invention, though exclusively by way of non-limiting example, will presently be further elucidated. In the drawing:

Fig. 1 shows a first embodiment in cross section;

Fig. 2 shows a second embodiment in longitudinal section;

Fig. 3 shows a section along the line III-III in Fig. 2;

Fig. 4 shows a part of a top plan view of a third embodiment on an enlarged scale; and

Fig. 5 shows a section along the line V-V in Fig. 4.

Fig. 1 schematically represents, in cross section, a cylindrical container 1, in which a reduced pressure can be created by means not shown. Within the container 1, a cooling body 2 is disposed above two inclined guide members 3, which are provided along their upper edge with distribution means 4, with which a water film running down along the guide members 3 can be created. The distribution means 4 are supplied by a water supply 5. By creating a reduced pressure in the container 1, a part of the water film will evaporate and freeze onto the cooling body 2. As a result of the evaporation, the temperature of the non-evaporating water of the water film on the guide members 3 is lowered, as a result of which an ice-water mixture is formed, which collects adjacent the undersides of the guide members 3 and is removed from the container 1 via a drain 6, partly under the action of a pump 7 in a conduit 8 connected to the drain 6. Placed above the drain 6 is a sprayer 9, by which the ice-water mixture to be drained can be kept moving, such that it does not proceed to freeze on the wall in the vicinity of the drain 6 or lump together, as a result of which the drain 6 could become blocked and clogged. The sprayer 9 is supplied by a conduit 10 communicating with the water supply 5 via a conduit 11 including a cock 12, and/or by a conduit 13 connected via a cock 14 and an ice filter 15 with the conduit 8 at a point downstream of the pump 7. Thus, the sprayer 6 can be supphed at will with warmer water coming from the water supply 5 or with colder water coming from the drain 6, or with a mixture of the two. Naturally, it is also possible to use, or admix, water having a different temperature coming from a different source, not shown. In general, it will be preferred to spray water or ice-water mixture coming from the conduit 8 because this has substantially the same temperature as the ice-water mixture at the drain 6. If ice deposition is feared, or if ice deposits which are being formed or have been formed are to be removed, it may be elected to supply or admix water having a higher temperature.

Fig. 1 further represents a conduit 16, with which water from the conduit 11 and/or the conduit 13 can be supphed to a point in the drain 6, which embodiment will be further elucidated in the discussion of Figs. 4 and 5. Figs. 2 and 3 represent a device for producing an ice-water mixture which, similarly to the device shown in Fig. 1, is provided with a container 1, a cooling body 2, guide members 3, distribution means 4, a drain 6, a sprayer 9 and a conduit 10. In such a device, a number of drains 6 may be present, which may then each be provided with a sprayer. However, if a centrally arranged drain 6 is opted for, as shown in Fig. 2, then the guide members 3 connect to a slightly inclined bottom 17. To reduce the chance of freezing and lumping of the ice-water mixture onto that bottom 17, two additional sprayers 18 are present, which are placed at the ends of the bottom 17. Figs. 4 and 5 represent on an enlarged scale the part of the device around the drain 6. In addition to the sprayer 9, a pipe 19 is arranged which terminates in the drain 6 tangentially thereto. This pipe 19 is to be supplied via the conduit 16 designated in Fig. 1 and, upon supply of water, gives rise to a cyclone effect, that is, the drained ice-water mixture in the drain 6 is caused to rotate, so that, as a result of centrifugal action, the ice, being lighter compared with the water, is urged to the middle of the drain 6, so that the chance of this ice getting stuck onto the wall of the drain 6 is further reduced. It will be understood that within the framework of the invention as laid down in the appended claims many other modifications and variants are possible in addition to those already discussed hereinabove. For instance, the invention has been further elucidated on the basis of a device where an ice-water mixture is produced with a water film passed over guide members. It will be immediately clear to one skilled in the art that the invention is equally applicable, with equal advantage, in other production methods and devices, such as, for instance, those known from US-A-4,845,954 and WO-A-00/37865. In the foregoing exemplary embodiments, reference has been made to the supply of water to the sprayers and the pipe. In that connection, 'water' is understood to include water with additives, such as nucleating agents, for instance in the form of 5% NaCl. To obtain water or any other fluid having a relatively low temperature, it is also possible to elect to pass the conduit 10 along or through the cooling body disposed in the container. Further, also, several sprayers and/or pipes may be disposed adjacent the drain, for instance for generating a cyclone effect on the one hand and, on the other, for advancing the ice-water mixture to the drain and keeping the environment of that drain wet. Also conceivable, naturally, are containers having more than one drain, each having drainage provisions.

Claims

1. A method for removing an ice-water mixture via a drain from a container, such as a chamber for producing an ice-water mixture under a low pressure and under cooling, wherein the ice-water mixture in the container is stirred, characterized in that the ice-water mixture is guided to the drain while flowing over a container wall, and adjacent the drain water is supplied, such that an impulse is exerted on the ice-water mixture to be drained, so that at the drain a hydromechanical mixing is created.

2. A method according to. claim 1, characterized in that the water is supplied via at least one sprayer above the drain.

3. A method according to claim 1 or 2, characterized in that the water is supphed in the form of a jet into or at the drain.

4. A method according to claim 3, characterized in that the jet is supphed whilst directed tangentially to the drain.

5. A method according to any one of the preceding claims, characterized in that water is used in the form of an ice-water mixture.

6. A method according to claim 5, characterized in that water or ice-water mixture withdrawn from the drained ice-water mixture is supplied.

7. A method according to any one of the preceding claims, characterized in that water having a temperature above the freezing point of the ice-water mixture is supphed.

8. A device for removing an ice-water mixture via a drain from a container, such as a chamber for producing an ice-water mixture under a low pressure and under cooling, in which container stirring means are accommodated, characterized by stirring means in the form of water supply means disposed adjacent the drain.

9. A device according to claim 8, characterized in that the water supply means comprise at least one sprayer disposed above the drain.

10. A device according to claim 8 or 9, characterized in that the water supply means comprise at least one pipe terminating in or near the drain.

11. A device according to claim 9 or 10, characterized in that the water supply means in the form of a sprayer or a pipe are connected, remote from the drain, with a drain pipe connected to the drain.

12. A device according to claim 9, 10 or 11, characterized in that the water supply means in the form of a sprayer or a pipe are connected with a supply conduit passing to the container, for water to be transformed into an ice-water mixture.