US2498645A

US2498645A - Method of making ice

Info

Publication number: US2498645A
Application number: US28777A
Authority: US
Inventors: Frederick J Bobby
Original assignee: UNION ICE CO
Current assignee: UNION ICE CO
Priority date: 1948-05-24
Filing date: 1948-05-24
Publication date: 1950-02-28
Anticipated expiration: 1967-02-28

Description

Feb. 28, 1950 F. J. BOBBY METHOD oF MAKING ICE Filed May 24, 19.48

Patented Feb. 28, 195.()

METHOD OF MAKING ICE vFrederick J. Bobby, Berkeley, Calif., assigner to The Union Ice Company, San Francisco, Calif., a corporation of California Application May 24, 1948, Serial No. 28,777

Claims.

This invention relates generally to a process and method for manufacturing ice, and particularly to a process and method for manufacturing ice by the can system.

In the past, ice has been manufactured in ice plants by one of two systems. The first system, generally known as the c-an system, is one in which water to be Vfrozen is placed in suitable sheet iron cans which are then nearly submerged in cold brine. The brine is maintained at a low temperature by the evaporation of a refrigerant in a suitable container. lThe second system is known as the plate system of making ice and consists of a system in which a coil'or plate is immersed in the vwater to be frozen. The coils or plates are arranged for the evaporation of a suitable refrigerant, or for the circulation of cold brine. The removal of the heat from the water in this manner causes the formation of a layer of ice on each face-of the coil or plate.

It is an object of the present invention to improve the method of manufacturing ice by the can system in which, for a plant of a given size, a greater quantity of ice is produced at less cost.

Further objects and advantages of the present invention will appear from the following specication taken in conjunction with rthe accompanying drawing in which the figure is a diagrammatic showing of a can ice machine system incorporating my invention, in which vfour successive stages of the process are shown.

The method of producing ice by means ofthe can system may be shown diagrammatically in the figure by the four stagesof the process illustrated. This figure does not necessarily represent the simultaneous condition of adjacent cans in the brine tank. In this system, the water to be frozen is placed in suitable sheet iron ice cans lil which are then nearly submerged in a bath of cold brine Il which is retained by a brine tank I2 generally made of steel. The brine .Ii is maintained at a temperature of between 3 to 30 F. by means of the evaporation of a suitable standard refrigerant such as ammonia. The water in the can I0, being exposed onlyto the pressure of the atmosphere, will freeze at a temperature of 32 F. and the cold brine, at a temperature such as 15 F., Iwill absorb lheat required to cool the water from its original temperature to freezing temperature, that is 32 F. The brine also absorbs the latent heat of fusion of the water; the heat to cool the ice to the temperature of the brine Il; the heat from the ice cans lli; the heat transmitted by the tank l2; and `the heat to cover the other losses. kept in constant circulation in the tank l2 by means'of a propeller agitator i3 and the-purpose of this circulation is not only to equalize the temperature of the brine at all parts `of the tank, but also to increase the heat transmission by the greater velocity of the brine.

As soon as the lwater in the cans is cooled to 32 F., ice will begin to form on thesurfaces of the can I0. The rate of freezing is rapid at first and becomes progressively slower as the thickness of the layer .on the inner walls of `can lil increases. If the can l0 is left in the cold brine ll long enough, the water will entirely solidify forming a homogeneous block of ice lli as shown in Figure 1. The cans l of ice may then be removed from the brine and other cans filled with water may be inserted-in theirvplaces, thus making the process: of ice production continuous.

Due to the fact that'brine absorbs heat as prevously indicated, means mustbe providedfor removing this heat just as fast as it is absorbed in order to maintain its temperature constant. This is usually accomplished bysubmerging an evaporator for the refrigerant directly in the brine.

As is Well known to those skilled in the art, the freezing time or rate for a given thickness of ice as compared to the freezing time of ice of another thickness varies approximately as the square of the thickness, assuming all other factors remain constant. In other words, Vthe freezing time required to freeze ice 4 inches and '6 inches thick varies as the ratio of 16 to 36; also the freezing time is inversely proportionate to the temperature between the brine and the freezing water. Assuming therefore for the purposes of illustration that the layer of ice i6 built up on the inner walls of the ice cans lil follows the laws above set forth, it is obvious that the center core portion Ilwill be the last to freeze and that the time consumed in the freezing of the last 4 inches will greatly exceed the time consumed in the freezing of the first 4 inches of thickness of ice on the inner walls of the can Ill.

When a layer of ice It has been formed on the The brine il is Figure 1, there is a core in the center of the.'

block of ice ybeing frozen which is filled with water at a temperature of 32. At this point, I should explain that in this and the following examples I am assuming that the can I El is approximately 11 inches wide, 22 inches long and 50 inches deep. I should also explain that the width of the core I'I to which I refer in this and any other examples herein is 4 inches, as shown in the gure.

I propose to withdraw the water from the core I'I, leaving a shell or layer of ice I6 in the interior of the ice can I generally as shown in the gure. I then propose to ll core I1 with crushed ice or snow I8 and add only sufficient water thereto to completely ll the voids or spaces between the particles of ice or snow. The ice or snow which is introduced into the core I1 is, of course, at approximately 32 F. The water which is introduced is also introduced at a temperature of 32 F. whereby there'is no melting of either the block of ice I6 or the ice I8 put into the core I'I. It is obvious therefore that the new contents of the core I'i' will freeze n a lesser period of time than would the contents of the core if the same were entirely water at 32, for the reason that there is only a small quantity of water to be frozen. f

In tests which I have made I have discovered that approximately only 0f the filler of the core I'I need be water at a temperature of 32 1*".

The substitution of crushed ice or snow I8, or both, and a small quantity of water ata tem perature of 32 greatly hastens the production of a solid block of ice. For example, actual tests show that a block of ice 11 inches thick can be produced by my method, that is, With the introduction of crushed ice or snow into a 4-inch core, in the same length of time now required to freeze a block of ice '7l/ inches thick by the standard procedure. Speeding the production of a solid block of ice in a given plant means increased production of ice with the same equipment ordecreased consumption of power for'the production of the same quantity of ice .by the use yof the same equipment. There are several ways in which my invention may beiused, as shown in the following examples. As a standard for the following examples, I have taken a plant which may be generally described as follows, and which I will hereafter refer to as the standard plant:l

Number of cans in tank 432 Weight of each block of ice v31S Tons produced daily 45 Number oi blocks of ice produced each 24- hour period 300 Freezing time for block of ice hours 34.5 Number of cans per ton of ice produced per 24Y hours 9.6 Tons of refrigerant required per t0n of ice 1.6 Brine temperature degrees i 12 Ammonia saturation temperature degrees `6.5 Ammonia suction pressure 20.75 Split (difference between brine and ammonia temperature) 5.5 Ammonia liquid temperature (from condenser) degrees V '78 Kilowatt hours of power consumed per ton of ice produced (net including auxiliaries) 54 Example No. 1

to produce the same daily net tonnage, Ilo-wit, tons per day, as was produced in the standard plant. In this example, the filler I8 of snow or crushed ice used to ll the cores I'I is the product of the plant and is taken from the increased total or gross capacity of the plant. In order to ll the cores with the production of the plant, it is necessary to crush approximately 22% of the plants total production for this purpose.

Example stllladrd Number of Cans in tank 432 432 Weight of each block of ice 313 313 Tons produced daily 45 45 Number oi blocks of ice produced each 24- hour period 300 300 Freezing time for block f ice hours 34. 5 34. 5 Number of cans per ton of produced per 24 hours 9. 6 9. 6 Tons of refrigerant required per ton of ice-- 1. 6 1. 6 Brine temperature degrees-- 20 12 Ammonia saturation temperature do 14. 5 6.5 Ammonia suction pressure 28. 25 20. 75 Split (difference between brine and ammonia temperature) 5. 3 5. 5 Ammonia liquid temperature (from condenser) degrees 78 78 Kilowatt hours of power consumed per ton of ice produced (net including auxiliaries) 45. 6 54 From the above 1t w1ll be seen that by withdrawing the water in the Ll-inch core and substituting crushed ice and a smallcamount of water therefor, the freezing time is reduced as above pointed out. Specifically, it will be noted that the brine temperature may be allowed to rise from 12 to 20 whereby 18.75% less compressor capacity is required and a 15% savings in power is obtained.

Example No. 2

In the second example of a way of adapting my invention to the above standard plant, the ller I8 of crushed ice or snow is to be taken fromthe total or gross production capacity.v In this in# stance, the former compressor capacity is to be invention to the above standard plant, I propose used to meet new-operating conditions created by the availability of greater can capacity. In this example, the plant produces 52 tons of ice per day with the brine temperature being allowed to rise to 19.5.

Standard Example Plant Number of Cans in tank. 432 432 Weight of each block of ice 313 313 Tons produced daily 49 45 Number of blocks of ice pro ced each 24- hour period 330 300 Freezing time for block of ice hours 25. 7 34. 5 Number of cans per ton oi ice produced per 24 hours 8. 72 9. 6 Tons of refrigerant required per ton of ice- 1. 6 1. 6 Brine temperature "degrees" 19. 5 12 Ammonia saturation temperature v do 13. 5 6. 5 Ammonia suction pressure. 27 20. 75 Split (difference between brine and ammonia temperature) 6 5. 5 Ammonia liquid temperature (from i condenser) degrees 78 78 Kilowatt hours of power consumed per ton ton of ice produced (net including auxiliaries) 46 54 The advantages of the utilization of my invention as pointed out in this example are shown by the increased tonnage of ice produced and also the decrease in power consumed, in this instance 15% less than in the standard plant.

Esa-ample No. 3

In the third example` of a way of adapting my invention to the above standard plant, I propose that the crushed ice or snow I8 be furnished from an outside source but that the brine temperature can be allowed to rise to 19.75% and the same compressor capacity is used in freezing tank.

, Standard Example Plant Number of Cans in tank 432 432 Weight of each block of ice-- 313 313 Tons produced daily 59 45 Number of blocks of ice produced each 24- hour period 394 300 Freezing time for block of ice vhours 26. 5 34. 5 Number of cans per ton of ice produced per 24 hours 7. 45 9.6 Tons of refrigerant required per ton of ic l. 6 l. 6 Brine temperature degree 19. 75 l 12 Ammonia saturation temperature do 13. 75 6. 5 Ammonia suction pressure- 27. 25 20. 75 Split (difference between monia temperature) 6 5. 5 Ammonia liquid temp condenser) 78 78 `Kilowatt hours of power consumed vper ton of ice produced (net includmg auxiliaries) 46 54 The advantages of the use of my invention as illustrated in the above example are obvious. The increase of 1.4 tons of ice yper day represents an increase of 31% over the output of the standard plant. In addition, I show theuse of approximately 14% less power per ton of ice than consumed in the standard plant.

Example N o. 4

In the fourth example of a way of adapting my invention to the above standard plant, I propose that the temperature of the brine be held at 12 by addition of greater refrigerating effect and that the iiller of cracked ice vor snow be produced in the plant and taken from gross production capacity, in which event 22% of the gross production capacity is used in the cores.

Standard Example Plaut Number o Gans in tank 432 432 Weight of each block of ice 313 313 rlons produced daily 76 45 Number of blocks of ice produced each 24-hour period 506 300 Freezing time for block of ice hours.- 16 34. 5 Number of cans per ton of ice produced per 24 hours 5. 7 9. 6 Tons oi refrigerant required per ton of 1ce 1.6 l. 6 Brine temperature degrees-. 12 12 Ammonia saturation temperature do 6. 5 6. 5 Ammonia suction pressure. 21 20. 75 Split (difference between brlne and ammonia temperature) 5. 5 5. 5 Ammonia liquid temperature (from condenser) degrees 78 78 Kilowatt hours of power consumed per ton of ice produced (net including auxiliaries) 50 54 By using my invention the output of the plant is increased 31 tons per day or 69% over the tonnage produced in the standard plant. It will be noted that the power per tn of ice is slightly less than the power per ton of ice required by the standard plant. I am assuming that the efiiciency of the added refrigerating effect is the same as the original refrigerating effect.

Example N o.

In the fth example of a Way of adapting my invention to the above standard plant, the filler of cracked ice or Isnow is produced from an outside source- Further refrigeration effect in the way of more compressor capacity and a greater Example l Std Number of cans in tank 432 '432 Weightof each block .of ice- 313 313 Tons produced daily '97 45 Number of blocks of ice produced each 24- i hour period 648 `300 Freezing time for block 0' ce liours.- 16 34. 5 N umberpf cans per ton `of ice produced per i .24 hours 4. 45 9. 6 Tons of refrigerant required per ton of ice. l. 6 1. 6 .Brine temper ature. degrees `12 12 Ammonia saturation temperature do 6. 5 6. 5 Ammonia suction pressure 21 20. 75 Split (diierence between brine and ani- 4 monia temperature) 5. 5 5. 5 Ammonia liquid temperature (from con denser) degrees 78 78 Kilowatt hours of power consumed per ton of ice produced (net including auxiliaries) 50 54 ample shows an increased production of 52 tons of ice per day or a increase over the production of the standard plant. As in the 'previ ous example, the power consumed -per ton of ice produced is 'slightly less than the power per ton of ice yproduced in a standard plant.

From the foregoing, it will be obvious that by using my invention ina standard plant there are two general prots to b'e obtained. The first advantage is the increased 'production of greater quantities of ice with no increase in compressor capacity or power consumption. l The second advantage is derived yfrom the Aproduction ofthe same quantity of ice as before with the same or a lesser 'expenditure for plant capacity and power (consumption. y

Generally speaking, ice produced in accordance with my process is a better product in that the same does not shatter or crack resulting from strains which are frozen into the ice.` Shattering and cracking of blocks of ice may result in a loss of up to 5% of the total plant capacity in some instances. However, ice made in accordance with my process will, it is recalled, utilize cracked ice or snow which is already frozen and therefore already expanded, leaving little or no expansion to occur in the core. A more solid block of ice is obtained with fewer strains therein.

When the ice is made in accordance with my invention or process it may be made at a higher freezing temperature, resulting in a saving in equipment and compressor capacity. A smaller investment is required, that is, a smaller investment per ton of ice produced.

In addition, less operating and labor expense per ton of ice is required inasmuch as, in the examples above given, little or no more additional labor is required than in the standard plant referred to herein. In addition, maintenance and replacement costs per ton are likewise reduced.

It will be obvious that utilization of my process may eliminate chemical treatment in many localities. It will be recalled that the higher the freezing temperature the less pure the water need be and, conversely, the colder the freezing temperature the more pure the water need be to produce a satisfactory product. In the event the ice is made in brine at a high temperature, therefore, less pure water is required.

The water taken from the core l1 may .be reused in the freezing process, either in the block of ice with the crushed ice i8 placed in the core, or as a source of water to be placed in the cans l0 in the iirst steps of the operation, or in any other way that appears practical orproperv in the operation of any specic plant.

It will also be 'appreciated that the frozen material I8 placed in the core may be either crushed ice or snow as indicated or may be ice in any form, such as flakes, etc., to meet optimum conditions.

In all of the foregoing, I have assumed that the shell of ice in the can is suciently thick to leave a four inch core; I appreciate that eX- perimentation in a specific plant may show that a larger or smaller coremay be desirable to meet optimum conditions, in which event the shell of ice IB may be frozen thicker or thinner as desired without departing from the spirit of my invention. In any case, the percentage of ller in relation to the finished block may be varied to meet optimum conditions.

I claim: y

1. In a method of making ice by the can system, the steps of, first, forming a shell of ice on the inner walls of said can, second, withdrawing the unfrozen water from the said shell of ice and third, replacing the same with a mixture of crushed ice and water.

2. In a method of making ice blocks in which a quantity of water to be frozen is placed in a can, the steps of, forming a shell of ice on the inner walls of said can by heat transfer through the walls of said can, withdrawing the inner core of unfrozen water from said Shell of ice,`re placing the same with a mixture of ice and water andthen freezing saidmixture to form a solid block of ice integral with the shell.

3. In an improved method of making ice blocks, the steps of, placing Water to be frozen in a conta-incr, immersing said container in a heat absorbing medium, allowing a coating of ice to form on the inner walls of said container, withdrawing theunfrozen Water. from withinsaid coating of ice and replacing said water withice and water and retaining said container, shell, and ice and water mixture in said heat absorbing medium until said shell and said ice and Water have formed a homogeneous block of ice.

4. In an improved method of making ice in which water to be frozen is placed in a can which is immersed in brine and a layer of ice is formed on the inner Walls of said can, the improvement consisting in the steps 0f withdrawing unfrozen water from within said layer of ice before a homogeneous cake of ice is formed and replacing the same with a mixture of ice and water and retaining said can and mixture in said brine until a homogeneous cake of ice is formed.

5. In an improved method of making ice blocks in which water to be frozen is placed in a can partially immersed in cold brine and a layer of ice is formed on the inner walls of said can, the improvement consisting in the steps of withdrawing the inner core of said unfrozen water from said layer of ice before a homogeneous cake of ice is formed and replacing the same with a mixture, the major portion of which is cracked ice and the minor portion of which is water, and retaining said can, said layer of ice and said mixture in said brine until a homogeneous cake FREDERICK J. BOBBY.

REFERENCES CITED UNITED STATES PATENTS of ice is formed.

Number Name Date 1,271,879 Felt July 9, 1918 1,321,954 Voorhees Nov. 18, 1919