US2142386A - Apparatus and process for producing ice - Google Patents

Description

Jan. 3, 1939.

H. TlETZ APPARATUS AND PROCESS FOR PRODUCING ICE Filed Oct. 15, 1956 nozzdea wine/z form water feds arm); a-mzal/ radius Mawz/mmre 8/2011 the sum, off/1e J16? face Jen-r1022, oft/1e muer jei'ana t/ze ab-mduae ,vremare in the c/mmber s qrezzaer Man the vaiue off/1e sulfunzbe'an prearure 0/ water we 0C.

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Hans Taleaz lNVENT'OR WW ATTORNEYS HIS Patented "Ja n. 3,1939

' UNITED STATES 2,142,880 APPARATUS AND rac ig ass FOR r'nonncmo Hans Tietz, Leverkusen-Wlesdorf, Germany, assigncr to I. G. Farbenindustrie Aktiengeselllschaft, Frankfort-on-the-Main, Germany Application October 15, 1936, Serial No. 105,685

In Germany October 17, 1935 3 Claims.

This invention relates to the production of ice.

In an apparatus for producing ice by partial evaporation of water in vacuo it is diflicult to introduce the water into the vacuum chamber. On exit from the nozzles thewater evaporates so suddenly that it splashes on to the walls of the apparatus, freezes and thereby clogs the apparatus, whereby a continuous working of the apparatus is made impossible, or ice forms at the nozzle itself, so that the nozzle is finally completely clogged. To overcome these disadvantages many constructions, particularly heated nozzles, have been proposed. I

In accordance with the present invention clogging of the nozzles by the ice formed is avoided by introducing the water in a thin jet. This is obviously due to the fact that the capillary forces working against the evaporation are the higher the smaller is the diameter of the water jet. Now it might have been expected that at a certain temperature at which the water is introduced the diameter of the jet would have to be chosen so that the sum of the surface tension of the jet and the absolute tension in the vacuum chamber would at least be equal to the saturation pressure corresponding to the temperature of the water jet. However, it has been established that it sufilces if the sum of the tensions is greater than the saturation pressure at 0 C. This is probably due to the fact that the evaporation necessary for cooling the jet to 0 C. is so slight that it can be effected by mere evaporation at the surface without forming bubbles and splitting up of the jet caused thereby. That is to say the water jet must by means of a nozzle be given a surface of so small a radius of curvature that the sum of the pressure in the apparatus and the surface tension of the water jet is greater than the saturation pressure of water at 0 C. that is greater than 4.58 mm. of mercury. Only if the saturation pressure at 0 C. exceeds the aforementioned sum of the tensions can the water jet cool by further evaporation below 0 C. and thereby freeze P out as such. This, however, is the caseonlyif cury so that at a pressure of 3 mm. of mercury in the vacuum chamber the total pressure for rays of the radius indicated is equal to the pressure at the freezing point, that is to say each ray of a smaller radius is protected against evapora- (ci. szas tion and therewith freezing out at a pressure of 3 mm. of mercury.

My invention is further illustrated in the ac-. companying drawing in which:

Fig. I is a vertical section through an apparatus in which the present invention may be practiced and,

Hg. 11 is a detail view of the nozzle illustrated in Fig. I.

As shown in Fig. I, the, apparatus may comprise a vertical chamber l which is maintained under the desired vacuum by any suitable means. Within the vacuum chamber there is arranged an endless transport belt '2 which is provided with driving means (not illustrated).- The bottom 3 of the vacuum chamber is made in the form of an. inverted frustrum of a cone in order to collect the pieces of ice formed. The ice accumulating at the bottom of the chamber 3 then passes to the screw conveyor 4 which forces the ice out of the apparatus'in the form of a continuous rope or red. The ice is, of course, compacted at the exit point by means of the screw conveyor 0 thereby sealing the discharge opening of the vessel making it possible to maintain the vacuum within the vessel without the use of any special valves. The water is supplied to the apparatus through the pipe 5 which terminates in a number of branch pipes t. The pipes 6 are provided with a plurality of openings or nozzles l which form water jets of such a small radius of curvature that the sum of the surface tension of the water jet and the absolute pressure in the vacuum chamber is greater than the saturation pressure of water at 0 C. For example if an absolute pressure of 3 mm. of mercury is maintained in the vacuum chamber, the surface tension of the water jet must be at least equal to 1.58 mm. of mercury because the saturation pressure of water at 0 C. is 4.58 mm. of mercury. As indicated above, a water jet of 0.357 mm. has a surface tensionof 1.58 mm. of mercury. Accordingly if 3 mm. of mercury absolute are maintained in the chamber, eachwater jet must have a radius no larger than 0.357 mm. As shown the waterjets are impinged upon the endless belt 2 whereupon thejet is broken and the water spread out in the form of 8. him over the belt. Since the water in the form of a film has a lower surface tension than the jet, the sum of the surface tension of the water film on the belt and the absolute pressure in the chamber falls below the saturation pressure of water at 0 C. whereupon evaporation takes place with consequent cooling and freezing. In the above indicated manner the problem of ing means therein giving to a water jet formedin the apparatus so small a radius of curvature that the sum of the values of the pressure in the apparatus and of the surface tension of the water jet is greater than the value of the saturation pressure of the water at 0 C.

In a process for producing ice by partial evaporation of water in vacuo, the steps which comprise maintaining a low absolute pressure in a vacuum chamber, spraying water therein in a jet having so small a radius of curvature that the sum of the values of the surface tension of 2,14asee the water jet and the absolute pressure in the chamber is greater than the value of the saturation pressure ofwater at 0 C.

3. In a process for producing ice by partial evaporation of water in vacuo the steps which comprise maintaining a low absolute pressure in a vacuum chamber, spraying water therein in a jet having so small a radius of curvature that thesum of the values of the surface tension of thewaterjet and the absolute pressure in the vacuum chamher is greater than the value of the saturation pressure of water at 0 C. whereby evaporation of the jet is avoided and impinging the jet upon a surface to destroy the jet and to thereby reduce the aforesaid summation of values to a value lower than the saturation pressure of water at 0 0. whereby evaporation of the water and simultaneous freezing thereof may occur.

HANS mm.

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