METHOD AND APPARATUS FOR MAKING ICE

Abstract: Sluch ice is produced from brine continuously by a method involving both agitation and scraping action in relation to disc-like heat-exchange surfaces (23). Apparatus includes at least two heat-exchange surfaces (23) and scrapers (52, 53) which also act as agitators.

Description: &£.£&£__. MD ASSABA.CBS EQ& M&ltiQ ICS This invention relates to a method of and apparatus for the manufacture of ice, in particular, slush ice. The manufacture of ice in particulate form can be effected by a process in which ice is continuously formed on a cold surface and equally continuously removed from that surface by scraper blades. Because it is necessary that water should crystallize very rapidly on the cold surface, the process requires that the refrigerant flow should be at very low temperature with consequent high energy demand. It has also been proposed to overcome the problem by passing a coolant medium or a refrigerant, for example, a freon, through a multiple pipe array. However, the ice which forms on the pipes acts as a thermal insulator which slows down the formation of further ice. This fact results in increased operating cost per kilogram of ice formed coupled with an undesirably large volume for the operating tank accommodating the pipe array and a large amount of refrigerant necessary to fill the pipe array. Another proposal for the production of block ice involves a cold, heat exchange, surface of annular form which cooperates with a narrow scraper member rotatable about a vertical axis. In this prior proposed apparatus a coolant is circulated below the heat exchange surface and water lies above that surface so that there is continuous deposition and the scraper removes the deposited ice and any slush ice disposed above the surface with the result that block ice is continuously delivered from an outlet connected with the scraper. This prior proposal suffers from the disadvantage that the amount of energy consumed in continuously scraping the deposited ice will be substantial especially when added to the force necessary to deliver the block ice through the outlet connected to the scraper. According to the present invention in a first aspect there is provided a method of manufacturing slush ice comprising the steps of continuously supplying brine to an enclosure, passing the brine over a plane, disc¬ like, cold surface, continuously agitating the ambient brine while simultaneously scraping any ice which may form on the plane r disc-like, surface by the same means as those which produce the agitation, and continuously removing slush ice from the enclosure as it is formed. This action is preferably achieved by supercooling the brine by contact with a cooled disc¬ like surface so that water crystallizes out from the brine. It should be particularly noted that the contact between the brine and the cooled surface is intended only to supercool the liquid, deposition of ice on the surface being kept to a low level by the agitation and substantially eliminated by the scraping action. According to the present invention in another aspect there is provided a method of manufacturing slush ice comprising the steps of contacting with brine or water disc-like surfaces lying in vertical planes cooled by a freon or other refrigerant and continuously agitating the ambient brine or water while simultaneously scraping any ice which may form on the disc-like surfaces by the same means as produce the agitation. According to the present invention in a further aspect, there is provided apparatus for the production of slush ice comprising an enclosure, inflow means to the enclosure for brine to be converted to ice, plane, circular heat-exchange surface means within the enclosure and arranged to be connected to a supply of ref igerant, means supporting the heat-exchange surface means within the enclosure, scraper means rotatable with a shaft extending along the axis of the heat-exchange means and movable relatively to the circular heat-exchange surface, which scraper means additionally . serve to maintain brine to be converted to ice in a constantly agitated state whilst remaining in substantial contact with the corresponding heat- exchange surface, the water in the brine being converted to slush ice, and outflow means for continuously removing the slush ice from the enclosure. Preferably the enclosure has a natural or synthetic rubber cover. The heat-exchange surfaces may be duplicated and consist then of parallel circular plates accurately spaced from one another by a predetermined distance so that scraper means can clear the surface continuously thereby preventing deposition of a layer of ice. Preferably, the external surface of the or each heat-exchanger is polished thereby deterring ice deposition. With this construction it is important that the heat exchange action of each surface shall be substantially the same as that of each other surface. Apparatus embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:- Figure 1 is a side elevation, partially in longitudinal section, of apparatus in accordance with the invention ' for producing slush ice; Figure 2 is an end view of the apparatus, partly in section, to show the internal construction of the apparatus; Figure 3 is an end elevation of one of the rotors incorporated in the apparatus of Figures 1 and 2; Figure 4 is an internal view of a circular heat- exchanger plate forming part of the apparatus of Figures 1 and 2; Figure 5 is a side elevation of the heat exchanger plate of Figure 4; Figure 6 is an external view of the heat-exchanger plate shown in Figure 5; Figure 7 is an end, external, elevation of a cover plate of one heat-exchanger sub-assembly; Figure 8 is an end elevation of one heat-exchanger sub-assembly including both the items of Figure 4 and Figure 7; Figure 9 is a side elevation of the sub-assembly of Figure 8; and Figure 10 is an end view of a modification of the main embodiment. Referring now to the drawings, apparatus embodying the invention includes an enclosure 10 having two end plates 12,14 and also having a cover in the form of an annular rubber member 18 extending between support rings 20 of the end plates 12,14. The end plates are interconnected by several longitudinally- extending, square section tie rods 22 which serve to maintain the spacing between the end plates and to reinforce the enclosure defined, in part, by the end plates and to support one or more heat-exchanger sub- assemblies 23. The outline of the enclosure is generally circular as seen from Fig. 2. The enclosure is supported by front and rear brackets 25,27 which are themselves bolted to a support surface (not shown) . The left-hand (as shown) or front end plate 12, includes a bearing housing 24 and this accommodates two ball bearings 26 and a spacer bush 29, which journal a shaft 28 which extends into the right-hand end plate 14 which similarly carries a bearing housing 30. The front bearing housing also has a seal for example a "Chicago Rawhide" seal 31. The right-hand bearing housing 30 includes a "Chicago Rawhide" seal 32, and a single journal ball bearing 34. The shaft 28 extends beyond the bearing housing 24 and the extension is coupled by any suitable means to a shaft power source (not shown) such as an electric motor. The left-hand end plate 12, as illustrated, includes an inlet 40 (Fig. 2) for brine vertically below the bearing housing 24 and an outlet 42 (broken lines) for slush ice vertically above the bearing housing. Both inlet and outlet will, of course, be connected to appropriate piping. The end plates are both reinforced by radial ribs 41 which are enlarged at their radially outer ends to receive bolts 43 by which the end plates are secured to the brackets 25 and 27. Two disc-like heat-exchanger sub-assemblies 44 are supported on the ties 22 (only one shown) of square cross-section which are secured at each end to the end plates 12,14. The outer surfaces of the heat- exchange surfaces are externally highly polished and will preferably be of copper, a copper-nickel alloy or aluminium alloy so as to provide high conductivity. One of the freons or other refrigerant is delivered at 50,51 through the left-hand end plate 12 to the lower portions of heat-exchanger sub-assemblies and is withdrawn through an outlet manifold 48 in the upper portion of the left-hand end plate 12. The manifold extends between the end-plates. The freon will, of course, be supplied by an appropriate ref igerating apparatus. Details of each heat-exchanger sub- assembly will be given hereinafter with reference to Figures 4 to 9. To the left, as shown, of each heat-exchanger sub- assembly, a rotary agitator assembly 52 with scraper blades 53 is mounted fast for rotation with the shaft 28 and is spaced from the bearing assemblies of the heat-exchanger and from other scraper assemblies by spacer sleeves 54. Each agitator assembly with scraper blades 53 includes two tubular arms 55 (see particularly Figure 3) mounted on a boss 56 which is keyed to the shaft 28. Attachment brackets 58 for blades 53 are provided adjacent the radially outer extremity of each arm 55 and pivots are used to secure each blade to the corresponding arm. Each blade 53 is mounted in a blade carrier 61 which is itself pivotally supported on the boss 56 and the bracket 58 associated with each tubular arm 55 of the scraper assembly. As seen in Figure 2, the boss has two diametrically opposed bores 63 (one only shown) each of which receives a pivot pin 65 which engages in a spigot member 67 having an extension 69 engaged in a bush 71 of the elongate carrier member itself 73. The carrier member has a slot extending along substantially its whole length which receives the corresponding blade 53 and the latter is retained by grub screws (not shown) engaged in tapped bores 75 spaced along the length of the carrier member. Each blade is chamfered to give a cutting edge and is preferably made of TEFLON (Registered Trade Mark). Other plastics materials can also be used which are capable of retaining over long periods of use a reasonably sharp edge to ensure satisfactory scraping action of accumulated ice on the heat-exchange surfaces. It will readily be apparent from Figure 2 that the agitators and scraper blades do not extend radially with the aim of increasing agitation and reducing the power necessary to move the scraper blades over any deposited ice. Reference will now be made to Figures 4 to 9 which show in some detail the construction of each heat- exchange assembly. Each assembly comprises two disc¬ like plates 72,74, the plate illustrated in Figure 4 being provided with four similar lugs 76 by which the heat-exchange assembly can be mounted on the tie rods 22 extending between the end plates 12 and 14. That one of the disc-like members 72 of the heat-exchange assembly illustrated in Figure 4 has a central aperture 78 for the passage of the shaft 28 and, internally, has shallow ribs 80 which control the passage of the coolant from the inlet at the bottom of each disc to the outlet at the top. Two of these ribs 811,812 extend vertically in a plane containing the longitudinal axis of the apparatus as a whole. The remaining ribs 813/814 extend horizontally, alternate ribs being lateral extensions of the vertically extending ribs 811 & 812 and of a peripheral boundary rib 815 substantially of circular form. These alternating ribs leave spaces 816,817 for the passage of fluid a their respective tips so that in general terms two distinct sinuous paths are provided for the refrigerant, these paths ensuring a substantially even cooling effect over the whole of the disc-like surface of each heat-exchanger assembly. The peripheral rib 815 deviates from the circular path at the top 818 and at the bottom 819 of the disc-like member to accommodate inlet and outlet means 82,84 for the refrigerant. At the bottom an extended portion 820 of the peripheral ridge is rectilinear instead of arcuate and extending upwardly from this rectilinear portion is a web 86 which serves as a reinforcement for the lower supporting lugs 76. A similar web 88 is provided for the upper supporting lugs. The height of the ribs is identical and accurate machining is carried out to ensure that when mated with the corresponding cover plate, likewise of copper or the alternatives referred to above, relatively little brazing or welding material will be required in order to braze the two parts together. The ribs also serve to resist distortion which may otherwise arise owing to high internal pressures. As best illustrated in Figure 9 showing the parts assembled together upper and lower means 82,84 are provided for inlet and outlet purposes. Operation of apparatus in accordance with the present invention is straightforward and a large volume of slush ice can be produced on a continuous basis by providing the appropriate refrigerant flow to the interior of each heat-exchanger sub-assembly and similarly providing a continuous flow of brine to the interior of the enclosure defined by the end plates 12,14 and by the peripheral enclosure member 18. The continuous agitation taken with the smooth surfaces of the heat-exchanger sub-assemblies reduces the de¬ position rate, but any deposited ice will immediately be removed by the agitator/scraper blades hereinbefore described. Inlets and outlets both for the refrigerant and the brine are provided on the same end plate (12) thus simplifying connections. Inlets are at the bottom and outlets at the top. In practice the apparatus will, of course, be connected to the required facility which is to be cooled or air conditioned and as will be readily apparent it will be a simple matter to provide appropriate controls to match requirements of the associated plant merely by adjusting the flow rates of the fluids and the rate of rotation of the agitator assemblies. The important distinction of the method in accordance with the invention in relation to previously proposed methods is that because of the provision of agitation in relation to a heat-exchanger surface, ice particles are continuously formed in the brine whilst within the volume of the enclosure and the construction is deliberately such that little or no ice formation can take place on the heat exchange surfaces themselves. It will be readily apparent that the construction of the preferred embodiment hereinbefore described is particularly simple so that for an equivalent output of slush ice the capital cost is appreciably less than previously used apparatus known to the applicants. The apparatus has particular applicability to the fishing industry as it is possible to immerse freshly caught fish on a factory ship directly within the volume of the slush ice and brine carried in a storage tank supplied with ice from the hereinbefore described apparatus. If a plurality of heat exchangers are used within the same enclosure the agitating action in relation to each heat exchanger ensures that the performance of each one is substantially balanced with the performance of the remaining heat exchangers of the enclosure. In such a construction the supply of a refrigerant through the heat exchangers will, of course, be arranged in parallel. Slush ice manufactured in accordance with any aspect of the invention behaves as a liquid so that even at high concentrations it can be conveyed through pipes and can be stored in bulk. This provides particular advantages for air-conditioning system which frequently have peak demands. The storage ability enables the cooling effect to be stored using 'off peak' energy rates. The storage space is much reduced since each cubic foot of slush ice holds 6000 BTU in comparison with 620 BTU for chilled water. In comparison with heat-exchangers for the production of ice making use of tubular coolant pipes, apparatus in accordance with the present invention enables very simple and straightforward servicing. The enclosure member 18 is of rubber and after release of two steel clamping bands 90 and one of the support bracket assemblies 25 or 27 the rubber enclosure member 18 can readily be removed so that visual inspection is possible. If more complete disassembly is required, the bearing assembly at the righthand end of the end plate 14 can be removed and the three scraper assemblies and two heat-exchanger assemblies can be removed one by one. Replacement by use of a spare sub-assembly is readily possible with a minimum of lost operational time. The fact referred to above that it is possible always to have a buffer store of slush ice means that the associated apparatus can continue to function and it will not be necessary to have at any given plant a spare primary slush ice producing apparatus. This assembly can be further facilitated with the aid of a modified support for the end plate 14 as illustrated in Figure 10. The end plate 14 is supported in this modification by a support bracket 96 having an upper arcuate surface 98 corresponding to the arcuate surface of the end plate itself and if access is provided from below a main support 10 for the apparatus as a whole it is a very straightforward matter to slacken the single bolt 102 which passes through the main frame support, through the bracket and into a self-locking nut 104 welded to the end plate itself. Other advantages are: 1. Process is continuous. 2. Power consumption up to 30% lower than for conventional systems. 3. The size for a given output is small in comparison with conventional plant. 4. The ice has a small spherical structure and will not therefore harm delicate products. 5. Sea water can be used to generate clean ice. 6. Slush ice can be produced quickly from start up. 7. The modular nature of the apparatus enables specific capacities to be carefully matched merely by using more or less of the basic heat- exchange and agitator assemblies. 8. The horizontal rotational axis in the preferred construction avoids the need for thrust bearings.

Claims: CLAIMS 1. A method of manuufacturing slush ice comprising the steps of continuously supplying brine to an enclosure, passing the brine over a plane, disc-like, cold surface, continuously agitating the ambient brine while simultaneously scraping any ice which may form on the plane, disc-like, surface by the same means as those which produce the agitation, and continuously removing slush ice from the enclosure as it is formed. 2. A method according to claim 1, wherein the disc¬ like cold surface is continuously cooled with a refrigerant such as one of the freons. 3. A method according to claim 2, wherein the refrigerant and the brine flow generally upwardly with respect to the disc-like surface. 4. A method according to any one of claims 1 to 3, wherein the continuous agitation is accompanied by continuous scraping of ice from the cold surface. 5. Apparatus for the production of slush ice comprising an enclosure, inflow means to the enclosure for brine to be converted to ice, plane, circular heat-exchange surface means within the enclosure and arranged to be connected to a supply of refrigerant, means supporting the heat-exchange surface means within the enclosure, scraper means rotatable with a shaft extending along the axis of the heat-exchange means and movable relatively to the circular heat- exchange surface, which scraper means additionally serve to maintain brine to be converted to ice in a constantly agitated state whilst remaining in substantial contact with the corresponding heat- exchange surface, the water in the brine being converted to slush ice, and outflow means for continuously removing the slush ice from the enclosure. 6. Apparatus for the production of slush ice comprising means defining an enclosure, inflow means to the enclosure for brine to be treated, plane, circular heat-exchange surface means mounted within the enclosure with the said surface lying in a vertical plane and arranged to be connected to a supply of refrigerant, scraper means juxtaposed to the heat-exchange surface means which serve to scrape any ice which may form on the surface and simultaneously serve to agitate brine to be frozen, and outflow means from the enclosure for slush ice which has been produced. 7. Apparatus according to claim 5 or claim 6, wherein the heat-exchange surface means is coaxial with the scraper means. 8. Apparatus according to claim 5, claim 6 or claim 7 wherein the scraper means comprises two arms and scraper blades mounted on the arms. 9. Apparatus according to claim 7, wherein each scraper means comprises a scraper blade carrier pivoted on brackets of said arms and a plastics member defining a scraper edge. 10. Apparatus according to claim 8, wherein each blade is secured to the carrier by a slot and grub screws. 11. Apparatus according to any one of claims 4 to 9, wherein the enclosure defining means comprises two circular end plates and a rubber sleeve extending between the end plates, the rubber sleeve being detachably secured to the end plates by steel bands. 12. Apparatus according to any one of claims 4 to 11, comprising a plurality of heat-exchanger means and a number of scraper means capable of co-operating with all the heat-exchange surfaces of the heat-exchanger means. 13. Apparatus according to any one of claims 4 to 12 wherein each heat-exchanger assembly of disc-like form comprises a first part having internal ribs which act as spacers with respect to a second part of the assembly and also define at least one sinuous channel between the inlet and the outlet of the assembly. 14. Apparatus according to claim 13 wherein the second part is a plane cover plate and is brazed to the first part. 15. Apparatus according to claim 13 or claim 14 comprising four lugs with the aid of which the heat- exchange assembly is supported within the enclosure. 16. Apparatus according to any one of claims 4 to 15, wήerein the scraper means is rectilinear and mounted non-radially with respect to the axis of rotation of the shaf . 17. Apparatus for the production of slush ice comprising an enclosure, an inlet for brine to the enclosure at a lower level thereof and an outlet for slush ice at a higher level thereof, the inlet and outlets passing through the same end plate of the * enclosure, a flexible generally annular cover extending between and being held by steel bands to the end plates, a shaft rotatably supported lby bearings carried by the end plates, a plurality of heat- exchange, disc-like plates supported, non-rotatably on the end plates through tie rods and scraper arms mounted for rotation with the shaft, blades of the scraper arms contacting the two plane disc-like surfaces of each heat-exchanger, such blades serving, together with the arms to agitate the brine, and inlet and outlet connections for refrigerant fluid to the heat-exchangers respectively at the bottom and top of one end plate. 18. A method of producing slush ice substantially as hereinbefore described with reference to the accompanying drawings. 19. Apparatus for producing slush ice substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: MOGILEVSKY MIKHAIL, MOGILEVSKY, MIKHAIL
Applicants: SOLMECS CORP NV, SOLMECS CORPORATION N.V.
Application year: 1985
Main classification: F25C1
IPC codes: F25C1, F28F19