US2253512A - Apparatus for the production of ice - Google Patents

Description

Aug. 26, 1941. F. w. FECHNER EI'AL APPARATUS FOR THE PRODUCTIONOF ICE Filed Dec. 15, 1938 7 0 V, 7 Mm F r 1N VENTOR. HELM FEC FR/Tz ML HNER REM/HARD wussow M42 4Q AT TORNE Y5 Patented Aug. 26,. 1941 2,253,512 APPARATUS FOR THE PRODUCTION OF ICE Fritz Wilhelm .Fechner, Hamburg, and Reinhard Wussow, Berlin-Charlottenburg, Germany Application December 15,- 1938, Serial No. 245,812

In Germany November 28, 1936 1 Claim. (Cl. sz-mc) This invention relates to an apparatus for the production of ice in which heat is directly withdrawn from liquid by means of a source of cold, for example an evaporator or the like. According to the invention, in order to prevent the liquid from freezing on to the heat exchange walls of thesource of cold, an intermediate layer of a liquid which does not freeze easily, for example mercury, is introduced between the surface through which the heat is abstracted and" the liquid to be frozen.

It has previously been proposed to produce artificial plates'of ice by means'of a cooling apparatus, by allowing the cooling liquid to flow through .a vessel open on top and supplying the water to be frozen to the surface formed by the cooling liquid. In this known process therefore the cooling liquid is conducted, as the carrier of the cold, through the freezing vessel; this process however gives rise to certain difficulties. Either the cooling liquid is conducted at high speed through the freezing vessel irfwwhich case the surface of the cooling liquid cannot be level or it is conducted at a low speed in which case the transfer of cold and therefore the output of ice is only small. In any case, however, owing= to fluid friction, the surface of the cooling liquid will, on its passage through the vessel, move the layer of liquid to be frozen in contact with it, or the ice which is in the process of formation at this place to the outlet end of the vessel, where the thin sheets of ice formed collect in layers one upon another and separate from the cooling liquid and rise at the surface where they arrest the circulation of the water and make a return movement to the side on which the cooling liquid enters. Since, however, owing to their lighter weight, the particles of ice cannot sink down again to the boundary surface between the two liquids they become superimposed in layers at this place. clear plate of ice is way. --It has also therefore not possible in this been proposed in this case to provide a layer of liquid between the cooling liquid and the liquid to be frozen. If this be done a similar phenomena also of course occurs, since this layer of liquid is carried along by the The formation of a uniformly cooling liquid and the liquid to be frozen is again so that a clear 1 and smooth block of ice can be formed and there is no interference ,with the transfer of heat,

However, the task of the liquid which does not freeze .is rather to prevent ice from freezing on to the cooling device, than to act as a medium for transmitting cold. I

The apparatus in accordance with the invention can be used both for the production ofice and also forthe separation of dissolved substances from solutions by freezing'them out, for example for the separation of paraflin from crude oil or the like. For the sake of simplicity, however, reference is hereinafter made only to the production of ice.

In order that the invention may be readily understood and carried into effect, various forms of freezing apparatus in accordance with the plication of the invention to freezing cells of a known type, and finally Figure 9 illustrates how granulated ice or snow can be produced with the apparatus.

Referring to Figures 1 and 2, the reference 11 represents a vessel which contains water to be frozen and b is an evaporator arranged at the bottom of the vessel 1. Figure 2 shows a section through the evaporator taken on the line 2-2 in Figure l. The bottom of the vessel 11 or the evaporator b is covered by a thin layer of mercury c. When the apparatus is operated the cold produced in the evaporator b is first transferred to the layer of mercury c and from this to the water contained in the vessel 0.. A layer of ice is therefore formed on the surface of the mercury.

In the apparatusof the invention it is necessary that the evaporator should be horizontal and without upstanding projections, and therefore a free circulation of the refrigerant cannot be obtained directly as the result of the'evaporation process. It is therefore necessary to provide for an artificial circulation of the refrigerant which is effected by means of pump e. The reference I designates a pressure reducing valve i by which the pressure on the condensate from the condenser is reduced. The reference 9 designates a liquid separator. The mixture of liquid and vapour is drawn by the pump e from the evaporator b through the liquid separator g in which the vapour is separated and from which it is drawn off by the compressor which is not illustrated in the drawing. The liquid which is drawn in by the pump is injected into the injection pipe behind the pressurereducing valve 1 and aclosed circuit is thereby formed. In some cases the circulating pump e may be omitted, namely by arranging the liquid separator g in an elevated position outside the vessel a and arranging, instead of the pump circuit, a downwardly extending, siphon-like return pipe from the liquid separator g to the injection pipe. In this case, however, care should be taken that the lowest point ofthe siphon-like return pipe is sufficiently far below the point of connection to the injection pipe.

The ice which is formed on the surface of the mercury will grow to form a block of ice of greater or less thicknessaccording to the external conditions, such as the stagnancy or movement of the water and so forth, and then owing to its buoyancy will separate from the surface of the mercury and rise upwards without the production of cold being interrupted. If precautions are not taken and if, for example, the water above the surface of the mercury be in rapid movement, the ice formed will separate very quickly orin the form of a thin layer, so that a snow-like ice will be produced, which can be removed from the surface of the water, whereas, if the water in the vessel is stationary, relatively thicker layersof ice can be formed through the thickness of the ice which is obtainable in this manner still remains relatively small.

According also to the present invention, plates of ice of greater thickness are obtained by the provision in the region where the ice is formed of fixed, separate or continuous parts or surfaces which are good conductors of heat and project above the surface of the mercury; preferably these parts are so disposed that they enclose the area over which evaporation and freezing takes place.

Since these parts are good conductors-of. heat their temperature soon becomes the same as that of the mercury and the ice freezes fast on to these projecting parts. The plate of ice which is formed is therefore as it were adhered to the surface of the mercury and the plate of ice can consequently grow to any desired thickness. In order now to release the plate after it has attained the thickness desired, it is only necessary to heat these projecting parts by a warm medium, for example water, so that the plate of ice is thawed off from the points at which it is held. The plate of ice which is thus freed then rises to the surface owing to its buoyancy.

Figure 3 is a plan of an apparatus of the kind illustrated in Figure 1 having a number of such projections h by which the ice is held distributed around the periphery of the freezing zone of the evaporator. Figure 4 illustrates on a larger scale and by way of example how a device of this nature is combined with the parts shown in Figure 1. The references a, b and c designate, in this figure, the sameparts as in Figure 1. An injection nozzle 2' is arranged centrally in the projecting sleeve h to which the ice adheres. Normally, however, no medium is injected into the sleeve h. Owing to the conduction of heat by the material of the sleeve, which is made for example of iron, the temperature of this sleeve becomes approximately the same as that of the layer of mercury and the water freezes in the same manner as on the surface of the mercury to the iron cup which projects from the surface from the mercury whereby the entire plate of ice which is formed is held coherently together. When the plate is to be released, after the ice has reached a desired thickness, a warmer medium, for example brine,

' which may be in heat exchange relationship with the cooling water for the condenser, is injected through the injection nozzle against the upper- .cup-shaped end of this sleeve, whereby this end is heated and the adhering ice is thawed off. The thawing agentwhich is injected flows awayin the direction of the arrow indicated in the drawing. Instead of a number of separate points of adherence, a continuous pipe or passage can be arranged around the periphery of the evaporator at the level of the mercury, as is indicated in Figure 5. The method of operation is then exactly the same as previously described, that is to say in order to release the plate of ice which is formed, a thawing agent, for example warm brine, is passed in the direction of the arrows through the pipe k.

Figure 6 shows on a larger scale a particularly advantageous form of construction of a passage of this kind. The references a-d designate the same parts as previously. The peripheral passage k to which the ice adheres is formed in this case by the lower corner of the vessel a in whichthe water to be frozen is contained. The passage is of narrow, wedge-like shape and its height corresponds to the thickness of the plates of ice to be formed. With the apparatus the edges of the plates of ice formed are even and the space inside the vessel is well utilised for the production of ice. In this case also for thawing oif the block of ice formed a warm medium need only be passed through the passage It. On the other hand, in

' order to be able to use this passage as a protection from the outside. the vessel is provided, preferably at the end, with an outlet in the bottom, so that after the supply of thawing medium ceases the passage can be emptied. With this latter form of construction there is a relatively large surface to which the ice adheres and further owing to the conduction of cold through the walls of the-passage a ridge-like formation of ice can take place on these walls. In order to avoid difficulties arising therefrom, such as too firm adhesion and consequent delay in thawing, this surface of the passage which is in contact with the ice can be lined with a material which on the one hand is a poor conductor of heat and, on the other hand, only adheres weakly to the ice, for example, with the layer of rubber 1.

Ice making apparatus of this kind can be used for many different freezing purposes. If, for example, a homogeneous salt water ice is' to be manufactured, the water can simply be allowed to freeze in a stationary condition, the evaporator temperature'being as low as possible. Since any salts or constituents of the solution which may separate areheavier than the water above them which contains less salt, the salt accumulates at the place of separation on the smooth under surface of the ice. The salt must be frozen-in because equilibrium of the solution with the upper layers of water by diffusion only proceeds very slowly at these low temperatures. This is still more the case'as the temperatures of evaporation become lower, that is to say when the speed of with as high a velocity from salt can be bottom of the cell, a layer speed of freezing exceeds the speed of diffusion.

Then the salty constituents must be frozen-in in a state of fine sub-division so that a homogeneous ice is obtained.

Conversely if fresh water ice 'is to be produced from salty water, then the. water is circulated as possible above the freezing surface. This is illustrated in Figure 1'. In this figure m denotes a. stirrer which circulates the water to be frozen with greater or less velocity above the freezing surface. In consequence of the smooth surface of the ice the materials which separate are-washed away very effectively from the freezing surface. At the opposite endof the vessel, for the purpose of retaining the layer of mercury, there is arranged an edge n which projects only a small distance above the level of the mercury. Behind this there is a settlement vessel oin which the heavier constituents of the solution sink down during the circulation. Since the liquid in this settlement chamber does not take part in the circulating movements of the liquid in the vessel a but remains stationary therein, the heavier constituents collect, in the settlement chamber to an increasingly great extent during the course of be drawn off from time to time as they accumulate through the outlet valve 1). In this. way therefore an ice which is relatively poor in or free produced from salt water.

Two further forms of construction which can also be employed are illustrated by way of example in Figures '1 and 8 respectively. 7 Both figures 'show freezing cells which are flooded by the water to be frozen. Figure 7 shows a freezing cell q whichis open on top and in which the ice is formed in the interior of the cell. The formation of ice is limited at the cell by a transverse plate or bottom 1' which is, in the cell illustrated, provided in the middle the lower end ofof a known kind operation a and can a wall t so that a protective air chamber is formed at the under side of the bottom 1'.

Figure 8 shows a freezing cell it which is also and is closed on top. In this cell the formation of ice takes place on the outside around the cell whereas the cooling medium flows through the cell during the freezing periods in the direction indicated, by the arrows and leaves through the central pipe 22, whereas for the purpose of thawing off the ice formed the direction "of flow of the cooling medium is reversed in known manner. In this case also the bottom space is covered by a layer of mercury c and, similarly as in the construction according to Figure '1, this mercury layer is used not only for the actual transmission of cold but also for preventing the body of ice from adherlngto the bottom of the cell and to any extension thereof.

Finally, Figure!) illustrates a further form of construction which is intendedto enable ice to be produced in a finely divided form or to cool down liquid very suddenly. For these reasons this apparatus is particularly'suitable for the production of ice from salt water in which case the ice which is obtained in a finely divided condition can be compressed into the form of briquettes if it is not desired to use it in this finely I divided condition.

In Figure 9 the reference to denotes pipes and are closed at he bottom and assembled in a common evaporator.

, Instead of this, individual pipes can each be surwith an opening having a tubular extension which projects a through which air 3 for the purpose of clarifying the ice. annular chamber of mercury c is again introduced. The body of ice which is formed is therefore again in contact at the bottom with this layer of mercury at the surface of which, owing to the ice is formed without however adhering so'firmly to the bottom of the cell as to cause difliculty in thawing off the ice formed. In order to prevent ice from being formed also at the under side of the bottom surfaces, the central opening is connected to an extension of the wall of the cell by conduction of .cold by the mercury,

which is thereby formed at the' is cooled down by the nozzle into the mercury in the tube.

FRIT

rounded by a double pipe, as shown in Figure '7.

in which case the surrounding space acts as an Intothe bottom of these pipes conare introduced injection the water to be frozen is injected under pressure into the mercury which evaporator. Consequently, division of the water taming the mercury nozzles through which owing to the fine state of and the direct contact with the-cold mercury,

the injected'liquid freezes at once, which may be of importance for various other presses. Owing'to its great buoyancy in the heavy'mercury the finely divided ice rises rapidly to the surface and collects there from which it can then be removed by suitable conveying devices. Weclaim: Apparatus for the production .of ice comprising an evaporator, at least one mercury-filled tube in said evaporator, at least one injection nozzle at the bottom of each tube, and means for injecting liquid to be frozen through said z FECHNER. nEmHARD wussow.

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