ROTARY DRUM ICE MAKER

Abstract: An ice making machine comprising an evaporator drum (20) on axially aligned shaft and preferably having a plurality of finger-like projections (10) extending outwardly from the drum (20). Upon rotation of the drum (20) the drum (20) and fingers (10) pass through a liquid bath (11) and ice is formed thereon due to evaporation of a liquid refrigerant (19) within the drum (20) and fingers (10).

Description: "ROTARY DRUM ICE MAKER" This invention is concerned with ice making machine of the type which produce ice in relatively small discrete portions. • *** There is a significant requirement for ice in small 5 discrete portions for use in domestic or commercial applications in drinks and the like. A further commercial use for ice of this kind is in the fishing industry where particulate ice is required as a flowable mass for packing around a catch on a fishing boat. 10 Crushed ice, formed by mechanically crushing large blocks of ice, has been used for the above purposes but the crushing is time consuming and energy intensive thus adding substantially to the cost of manufacture. Crushed ice suffers the further disadvantage that the particle sizes 15 are uneven and generally speaking a mass of crushed ice is difficult to handle. Of recent years ice making machines have been proposed in which the ice produced comprises regularly shaped and sized portions of a variety of configurations e.g. blocks, 20 cylinders, hollow cylinders etc. The particulate ice so formed is suitable for use in drinks and in flowable bulk form as a cooling medium for commercial applications e.g. the fishing industry. There are however a number of distinct disadvantages 25 associated with the various types of ice making apparatus currently available for manufacture of particulate ice. All of the prior art ice makers operate on a batch process. Ice shapes are first formed during a refrigerating cycle and then harvested during a defrost cycle wherein hot refrigerant gases are employed on a reverse cycle to release 30 the shapes so formed. The ice shapes are then transferred (usually by gravity feed) to a storage bin for use as required. Because the ice making process requires a reverse cycle defrosting operation for harvesting, it is necessary to provide a separate refrigeration system for the storage 35 bin. It can be seen therefore that ice makers of this type are bulky, energy intensive, require a high capital outlay and in view of their complex construction and control systems, require a high degree of maintenance. Possibly the greatest disadvantage of prior art ice makers of the type described above is that their production efficiency is approximately half their theoretical capacity due to the cyclic batch process caused by the necessity to employ a defrost cycle for harvesting. The present invention aims to overcome or alleviate the disadvantages of prior art ice makers and to provide a compact, simple and energy efficient apparatus capable of operating on a continuous rather than batch process. According to one aspect of the invention there is provided an evaporator for an ice making apparatus comprising: rotatable evaporator means, at least part of said evaporator means extending in use into a liquid to be frozen to produce ice; inlet means communicating with the interior of said evaporator means to admit liquid refrigerant thereto; outlet means communicating with the interior of said evaporator means to remove gaseous refrigerant therefrom, said evaporator being adapted in use to receive a quantity of refrigerant liquid whereby ice will form upon an outer surface of said evaporator extending into said liquid- as the evaporator undergoes rotation and ice in contact with said evaporator is caused to at least partially melt when above the level of said liquid refrigerant. • Preferably the evaporator means comprises a hollow substantially cylindrical body with axially aligned shafts at each end for rotation of said evaporator means. " Preferably said inlet means and said outlet means are associated with at least one of said axially aligned shafts. Preferably said one or more substantially radially extending projections comprise hollow finger-like projections. According to another aspect of the invention there is comprised an ice making machine comprising:- a rotatable evaporator means as described above; drive means for rotation of said evaporator means; a container for liquid to be frozen to produce ice; a refrigerant compressor and condenser operatively connected to said evaporator means; and means to remove ice formed on said outer surface of said evaporator. Preferably the drive means includes means to selectively control the speed of rotation of said evaporator means. Preferably said container for liquid to be frozen to produce ice includes means to maintain a liquid at a predetermined level within said container. Preferably said means to remove ice comprises wedge means adapted to engage between said evaporator and ice formed thereon as said evaporator rotates. According to yet a further aspect of the invention there is provided a method of continuously producing ice from a liquid comprising:- admission to a rotary evaporator as defined above of a quantity of liquid refrigerant whereby upon rotation of said evaporator, ice is formed on that portion of the evaporator in contact with the liquid to be frozen below the level of liquid refrigerant and ice in contact with said evaporator above the level of liquid refrigerant is caused to at least partially melt. A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:- FIG. 1 illustrates a side elevation, and OMPI FIG. 2 illustrates a cross sectional end elevation. In FIG. 1 the apparatus comprises a hollow cylindrical drum 1 rotationally mounted on axial shafts 2 and 3 which are journalled in bearings on support brackets 4 and 5 respectively. A variable speed electric motor 6 is operatively connected to shaft 2 by any suitable means such as gears, vee belt and pulleys on chain and sprocket. Shaft 3 is a hollow tube through which liquid refrigerant inlet 7 and gaseous refrigerant outlet 8 communicate with the interior of drum 1. Inlet 7 and outlet 8 communicate with the drum interior via a rotary carbon ring seal (not shown) mounted within seal housing 9. The seal is connected to concentric tubes (not shown) extending through shaft 3 into the interior of the drum 1. Also mounted within the interior of drum 1 are oil return plates (see FIG. 2) to collect lubricating oil entrained in the liquid refrigerant. The collected oil is returned to the compressor (not shown) via the gaseous refrigerant outlet 8. Around the exterior of the drum surface are mounted a plurality of finger-like projections 10. These projections are hollow, sealed at their outer end but communicate with the interior of the drum at their inner end. The finger-like projections 10 are aligned ih spaced axial arrays whereby upon rotation of drum 1 the row of finger-like projections forming the array follow the same path. Mounted below the drum 1 is a water trough 11 with a water inlet 12 and a drain outlet 13. The water inlet is fitted with a constant level control {not shown) such as a float valve or the like. Drain outlet 13 comprises at its inner end an inverted U-shaped nozzle thus permitting the outlet 13 to be selectively operated as a siphon. FIG. 2 is a cross section along the line A-A showing the interior arrangement of drum 1 and the ice harvesting device. Within drum 1 are situated oil return plates 14 and the concentric gaseous liquid refrigerant tube arrangement 15. The harvesting device 16 comprises a series of curved stainless steel strips pivotally mounted at one end 17 and biassed under gravity towards the drum 1. The strips are spaced to permit finger-like projections 10 to pas closely between adjacent strips. The strips are shaped to engage the drum at their free ends to form a tangential ramped surface whereby ice formed on the finger-like projections is removed by a wedging action by adjacent strips on either side of the finger-like projections 10 as drum 1 rotates. The ice shapes thus harvested then fall into collection chute 18 for transfer to a refrigerated storage bin (not shown) . The operation of the ice maker according to the invention will now be described with reference to FIG. 2. With the refrigerant compressor and condensor operating a quantity of liquid refrigerant 19 collects in the lower part of the interior of drum 1. Gaseous refrigeran is formed in the remaining part of the drum due to evaporation of the liquid refrigerant. With a trough 11 of water (filled to the level shown) underneath the drum 1, ice will form on those portions of the finger-like projections extending into the water. As the drum is rotated in the direction of the arrow, further projections 10 will enter the water bath and have ice formed thereon. During rotation of drum 1, the liquid refrigerant remains in the lower part of the drum thus ensuring that the cooling effect is restricted only to the surface of the drum and projections in contact with liquid refrigerant. The gas above the liquid refrigerant, having evaporated by absorption of heat from the water surrounding the projections, is at a higher temperature than the liquid. As the drum rotates heat is absorbed internally from the gaseous refrigerant and externally from surrounding air at O PI ambient temperature into that portion of the drum and projections above the liquid refrigerant level. The amount of heat absorbed in this manner is sufficient to melt that portion of the ice shape in direct contact with the projections before the drum rotates to engage the harvesting fingers with the ice shapes. Continued rotation of the drum causes the harvester fingers to wedge between the ice shapes and the drum thus forcing the shapes to disengage from the projections. The ice shapes fall under the influence of gravity into a hopper which directs the shapes to a refrigerated storage compartment for use as required. By suitably adjusting the speed of rotation of the drum by the variable speed drive, the thickness of the ice shapes can be varied as required. After a prolonged period of operation, there may be found in the water trough an increased concentration of dissolved salts as substantially pure water is removed as ice shapes. Depending on the quality of the input water supply, the trough may be periodically drained via the inverted U-shaped siphon tube 13. The control of the siphoning may be effected by any known timing device and or solenoid operated valve. Although the invention has been described with reference to a single preferred embodiment, it will be readily apparent to a skilled addressee that many modifications or variations may be made to the invention without departing from the spirit and scope thereof. For example, the rotary evaporator of the invention is preferably constructed of a metal with good heat transfer characteristics. For this reason the thickness of metal is kept to a minimum consistent with the operating pressures, which dependent on the type of refrigerant used may be in the range 0.1 psig to 50 psig. The drum and projections (and particularly the exterior surfaces thereof) are preferably corrosion resistant and may be treated with any OMPI suitable corrosion resistant coating e.g. chrome plating. The refrigerant compressor and condensor may be of any known type of suitable capacity and refrigerant control may be effected by any of the following known control devices or their equivalent i.e. high side float, thermostatic expansion valve, automatic expansion valve, capillary tube. The shape of the finger-like projections may be varied to suit the capacity requirements of the apparatus or the end use purpose of the ice shapes. For example the projections may be long and thin, short and squat and their cross section may be round, square, polygonal or the like. In addition, the finger-like projections may be adapted for selective removal from the evaporator by for example a screw threaded engagement therewith or a suitable socket and spigot connection or the like. In this manner, the shape of the ice portions formed with the invention may be selectively varied. The apparatus may be adapted to produce large ice shapes at high production capacity by constructing the device with appropriate dimensions, choice of refrigerant and compressor capacity. Such ice shapes may be suitable for use in the holds of fishing vessels " or the like. It is considered that a miniature form of the invention could be incorporated in the door of a domestic refrigerator to provide ice shapes for drinks and the like. Other larger forms of the invention would have application in commercial situations such as hotels, bars and the like or with appropriate modification the apparatus could be employed in the manufacture of frozen shaped conf ctions. In a further modification, the invention may comprise a smooth surfaced drum without projections for the manufacture of flake ice. It is considered that the invention represents a substantial improvement over prior art ice makers in that its relatively simple construction and simple controls give rise O PI to an apparatus which is inexpensive to construct and operate and which requires a minimum of maintenance.

Claims: CLAIMS : 1. An evaporator for an ice making apparatus comprising:- rotatable evaporator means, at least part of said evaporator means extending in use into a liquid to be frozen to produce ice; inlet means communicating with the interior of said evaporator means to admit liquid refrigerant thereto; outlet means communicating with the interior of said evaporator means to remove gaseous refrigerant therefrom said evaporator being adapted in use to receive a quantity of refrigerant liquid whereby ice will form upon an outer surfac of said evaporator extending into said liquid as the evaporator undergoes rotation and ice in contact with said evaporator is caused to at least partially melt when above the level of said liquid refrigerant. 2. An evaporator as claimed in claim 1 wherein the exterior surface thereof includes one or more substantially radially extending projections. 3. An evaporator as claimed in claim 2 wherein said oneormore projections are selectively removable from said evaporator means. 4. An evaporator as claimed in any one of the preceding claims wherein the evaporator means comprises a hollow substantially cylindrical body with axially aligned shafts at each end for rotation of said evaporator means. 5. An evaporator as claimed in any one of the precedin claims wherein said inlet means and said outlet means are associated with at least one of said axially aligned shafts. 6. An evaporator for an ice making machine substant¬ ially as hereinbefore described with reference to the accompanying drawings. 7. An ice making machine comprising:- a rotatable evaporator means as defined in any one of claims 1-6; ^HE OMPI drive means for rotation of said evaporator means; a container for liquid to be frozen to produce ice; a refrigerant compressor and condenser operatively connected to said evaporator means; and means to remove ice formed on said outer surface of said evaporator. 8.. An ice making machine as claimed in claim 7 wherein the drive means includes means to selectively control the speed of rotation of said evaporator means. 9. An ice making machine as claimed in claim 7 or claim 8 wherein said container for liquid to be frozen to produce ice includes means to maintain a liquid at a predetermined level within said container. 10. An ice making machine as claimed in any one of claims 7-9 wherein said means to remove ice comprises means adapted to engage between said evaporator and ice formed thereon as said evaporator rotates. 11. A method of continuously producing ice from a liquid comprising:— admission to a rotary evaporator as defined in any one of claims 1-6 of a quantity of liquid refrigerant whereby upon rotation of said evaporator, ice is formed on that portion of the evaporator in contact with the liquid to be frozen below the level of liquid refrigerant, and ice in contact with said evaporator above the level of liquid refrigerant is caused to at least partially melt. O PI

Inventors: CHAPMAN WARWICK DAVID, CHAPMAN, WARWICK, DAVID
Applicants: HARRISON FREDERICK JOHN, PERKINSON PATRICK GEORGE, HARRISON, FREDERICK, JOHN, PERKINSON, PATRICK, GEORGE
Application year: 1982
Main classification: F25C1
IPC codes: F25C1