Ice generating machine

An ice generating system including an ice generating assembly (160) including a plurality of plates (28) having internal coolant passages (28A) with the plates clamped together by tension bolts (51) with spacers (54) between adjacent plates to space the plates and allow the formation of ice therebetween. Water is pumped into weirs (37) positioned above each plate and permitted to flow over both plate surfaces for forming ice. The spacers serve to prevent the flow of water over the plate edges so the ice will not mechanically lock on the plates. The ice is released from the plates by pumping warm gases through the coolant passages and transporting the released ice by screw conveyors (55) positioned beneath each plate bay.

FIELD OF THE INVENTION 
An improved plate-type ice maker configured primarily to be transported on 
a vehicle. 
BACKGROUND OF THE INVENTION 
Recent advances in agricultural technology have allowed the harvesting and 
packing of produce directly in the field. After injecting a water and ice 
solution, commonly referred to as liquid ice, into the cartons the produce 
is ready for shipment to the market. By use of a portable icing station 
close to the harvest field, two main benefits are derived. Firstly, the 
icing equipment can be amortized over a longer period throughout the year 
because the equipment can be used with more types of produce at different 
locations, and secondly, travel time and costs of transportation for the 
produce are reduced significantly by doing away with the time previously 
necessary to transport the produce to a fixed location ice plant. 
In the past, portable ice generating equipment has been limited in 
generating capacity. Usually, such ice generating equipment utilizes a 
plate ice generator in which a liquid coolant is circulated through the 
center of a plurality of plate assemblies and water is passed over the 
exterior and allowed to freeze into ice sheets. Thereafter, by purging the 
plates of coolant and passing hot gas therethrough, the ice sheets are 
caused to disengage and drop downward for transport to a storage bin. Such 
generators have been limited in overall capacity due to the limited number 
of plates that have been mounted in the freezing section of a portable 
generator. Additionally, it has been usual to freeze on only one side of 
the plates. Further problems have existed with the ice encircling the 
plate ends and locking the ice sheet to the plates or, due to surface 
design, ice latching to the plate surface thereby making it difficult to 
disengage. 
Attempts to solve the locking problem have involved either the limiting of 
the water flow to the center section of the plates to prevent the flow of 
water adjacent the edges of the plates, or the circulation of a hot fluid 
through passages in the edges of the plates to prevent the formation of 
ice in that area. Naturally, both of these designs have limited the 
overall capacity of the freezing unit. Additionally, if the ice is formed, 
separated from the plates, and then exposed to water, it can refreeze into 
a solid mass if the temperature of the ice is low enough. To prevent this 
occurrence, it has been common to limit the overall quantity of water 
passed over each plate in an effort to limit the amount of water dropping 
from the plates onto the separated ice. 
It is the purpose of the present invention to provide a portable ice 
generator having a significantly greater ice making capacity than previous 
portable machines. Further, the invention allows for positive 
disengagement of the ice sheets from the plates and limits refreezing of 
the ice for easier handling once it is separated from the plates. 
SUMMARY OF THE INVENTION 
An ice generating assembly comprising a plurality of internally cooled 
plates positioned in parallel side-by-side relationship in an ice 
generating assembly. Insulating spacers are positioned between the outer 
edges of the plates and tension rods passing through platens fixed to the 
end of each plate are tightened to squeeze the plates and spacers together 
into one integral assembly. Thereafter, coolant is passed through passages 
in the plates and water is evenly distributed over the plate outside 
surfaces while being excluded from the end regions by the spacers. After 
ice is formed, the coolant is purged from the plate passages and hot gas 
is passed therethrough to separate the ice from the plates. The separated 
ice drops downward to a screw conveyor and is broken into pieces which are 
transmitted by the conveyor to a storage area. The conveyor housing 
includes openings to allow the escape of liquid and limit the refreezing 
of the ice into a solid bulk.

DESCRIPTION OF A PREFERRED EMBODIMENT 
In FIG. 1 is shown an ice generating system 10 mounted on a trailer 11 
comprised of a flatbed 12, wheels 14, and a stanchion 15. The ice 
generating system is shown in FIG. 5 and comprises an ice generating 
assembly 16, a condenser 17, a compressor 18, a high-pressure receiver 19, 
a low-pressure receiver 20, and a coolant pump 21. The compressor 18 
receives the refrigerant which it compresses and circulates as a gas 
through the coils 25 where it is condensed to a liquid, and circulated to 
the container 19A of the high pressure receiver 19 and the container 20A 
of the low-pressure receiver 20. The pump 21 receives coolant from the low 
pressure receiver and passes it through a valve C to a liquid manifold 26 
from which it passes through the ice generating assembly. The liquid 
circulates from the lower header 27 up through the coolant passages 28A of 
the plates 28 to expand and absorb heat before collecting in a top header 
29, and then flows through the gas manifold 30 and the valve D back to the 
low pressure receiver 20. This cooling cycle occurs while a water pump 34 
is functioning to pump water from a sump 35 up through a vertical pipe 36 
to weirs 37. This water then trickles down the plate sides for the 
formation of sheets of ice 38 (FIG. 4) on the outer surfaces of the 
plates. 
For separating the ice from the plates, a defrost cycle is initiated 
wherein the coolant pump 21 is shut down and valve A opens to allow hot 
gas from the compressor to pass through the conduit 40 and the gas 
manifold 30 into the top header 29 for purging the plate passages 28A of 
coolant. Thereafter the gas circulates out through the lower header, the 
manifold 26 and through a back-pressure regulator valve E. The valve C, 
being closed, prevents passage of the gas to the low pressure receiver 
through the pipe 41. The back-pressure regulator at first is locked open 
by a regulator proper 42 which acts to open the valve through the action 
of energization of the solenoid 44. The opening of the valve F causes the 
regulator proper to go full open for a specified period of time. 
Thereafter, the solenoid is de-energized allowing the back-pressure 
regulator valve E to function normally to regulate the back-pressure of 
the gas passing through the line 46 back to the low-pressure receiver. By 
regulation of the pressure, optimum heating of the freezing plates is 
effected. During this time, a conveyor 50 is energized to rotate and 
transport to storage (not shown) the ice falling from the freeze plates. 
In accordance with the invention, each bank of the ice generating assembly 
is comprised of a sandwich construction to permit high density positioning 
of the freezing units and allow for a quick release of the formed ice from 
the plates. Accordingly, the ice generator is comprised of a plurality of 
banks of plates 28 each having internal passages 28A as shown in FIG. 2. 
Attached to these plates are brackets 53 extending from the ends and 
through which tension bolts 51 are passed for holding the plates together 
in side-by-side spaced relationship. Positioned between the plate ends are 
the spacers 54 made of an insulating material of sufficient rigidity to 
permit some compression while maintaining the plates in spaced 
relationship. These spacers are compressed against the outer edges of the 
plates so as to prevent the circulation of water along the plate ends. In 
this manner, ice is prevented from freezing at the plate edges which 
alleviates the problem of the ice mechanically locking to the plates and 
not releasing during the defrost cycle. 
Positioned at the top of each plate is a weir 37 comprising an open-topped 
box structure having side walls 55 with a series of notches 56 in the top 
edge. Thus, water is pumped into each of these box structures by the pump 
34 forcing the water through the distribution pipe 36 to fill the weir 
until it begins flow out the bottom of each of the "V" cuts. In this 
manner, the water is evenly distributed along the sides of the plates for 
an even buildup of ice on the plate vertical surfaces. 
During the defrost cycle, hot gases are forced through the plates of each 
bank resulting in the plate surfaces warming and causing the ice to 
release therefrom. The ice drops down into contact with the conveyor 50 
positioned beneath the plate bank and comprising a screw 56 having notches 
57 in the edges to break up the ice sheets. Thus, the ice is moved to one 
end of the bank where it drops into a second conveyor 60. Excess water 
falling from the plates during the freeze cycle flows through the holes in 
the screen trough 52 and into the tank 35. The ice is carried away by a 
conveyor under each bank in a manner so as not to be exposed to water 
dropping from the plates of another bank thereby to maintain the ice 
relatively dry. 
Thus, it can be seen that there is provided a compact structure of 
parallel-positioned plates spaced apart just enough to allow the formation 
of ice on both surfaces as the water is caused to trickle evenly down the 
plate outer surfaces while coolant is passed through the internal passages 
28A. In this manner, a compact and efficient ice generating assembly is 
provided, enabling the generation of a much greater capacity of ice since 
the plates are positioned closer together and both surfaces are utilized 
for freezing. With the sandwich structure, the insulating spacers 54 
prevent the formation of ice at the plate edges thereby allowing for a 
shortening of the defrost stage because the ice releases efficiently from 
the plate surfaces. 
In the usual portable structure, there is provided the first trailer 11 as 
described carrying the complete ice generating assembly. Usually 
accompanying this trailer is a second trailer (not shown) for carrying ice 
storage containers into which the screw conveyor 60 comprising a power 
driven screw 61 in a screen trough 62 and a solid trough 64 transports the 
ice as it is formed. Notches 65 in the screw assist in breaking up the ice 
for easy transport. Naturally, the banks are defrosted one at a time in 
consecutive order so as not to overload the screw conveyor and to make 
efficient use of the warm compressor gases as they are cycled from bank to 
bank. In this manner, a very high capacity ice generator is provided which 
has proven to generate as much as 250 tons of ice in a 24 hour period. The 
ice has been used effectively in forming liquid ice for the cooling of 
produce, but naturally can be used for many other purposes.