US1844136A - Evaporator for refrigerating systems - Google Patents

Description

Feb. 9, 1932. R. s. NELSON EVAPORATOR FOR REFRIGERATING SYSTEMS Filed Jan. 24, 1930 2 Sheets-Sheet l Feb. 9, 1932. R, s* NELSON 1,844,136`

EVAPORATOR FOR REFRIGERATING SYSTEMS Filed Jan. 24, 1930 2 Sheets-Sheet '2 Patented Feb. 9, `1932 UNITED STATES PATENT' OFFICE RUDOLPH S. NELSON, OF ROCKFORD, ILLINOIS, ASSIGNOR T0 THE HOOVER. COMPANY, OF NORTH CANTON, OHIO, A CORPORATION OF OHIO 'EVAIPORATOR FOR REFRIGERATING SYSTEMS Application filed January 24, 1930. Serial No. 423,125.

The present invention relates to the art of refrigerating and more particularly to evaporators adapted for use in refrigerating systems in which a -plurality of refrigerants are simultaneously evaporated to produce a cooling edect.

Continuous absorption refrigerating sys? tems employing a single refrigerant in combination with an inert or neutral gas are Well known. In such a system the inert gas is circulated between the evaporator and the absorber for the purpose of maintaining the total pressure in these parts 'the same as that in the other parts of the system, although the partial pressure of the refrigerant changes. An example of such a. system is found in the U. S. Patent to Geppert, 662,690. As an im provement on this system it has been proposed to substitute a second refrigerating` agent for the inert gas so that both the main cooling agent and the auxiliary pressure equalizing agent may be condensed before they are introduced into the evaporator, the object being to increase the efliciency and cooling effect of the system. Ammonia and propane perhaps constitute the best combination heretofore suggested as the main and auxiliary refrigerants for this purpose.

ln attempting to operate a system of this kind, one of the chief diliicultiesencountered has resulted from the fact that the two liquid refrigerants, which from the nature of the system must be immiscible, 'formlayers or strata in the evaporator so that one blankets the other and prevents or retards evaporation. This is true even though an ordina@T series of plates or disks are provided in the evaporator, since both refrigerante rest upon any given bao.

object of the present invention is to provide an evaporator which is so constructed that a plurality of refrigerants may be fed therein and maintained in separate positions so long as they are in their liquid phase but o that simultaneous evaporation of all is a each exposed to the vapor phase of the other description taken in consideration with the accompanying drawings in which Figure l is a vertical cross sectional View of an evaporator illustrating the principles of the invention.

Figure 2 is a horizontal cross sectional view of the evaporator of Figure l.

Figure 3 is a plan view of a modified form of cup adapted for use in place of the plate shown inthe evaporator of Figure l.

Figure 4 is a cross sectional view of the cup on the line 4-4 of Figure 3 and Figure 5 is a cross sectional view of the cup of Figure 3 taken on the line 5-5.

Figure 6 is a fragmentary cross-sectional view of the upper portion of a modified form of evaporator similar to that of Figure l.

Figure 7 is a diagram of a refrigerating system having an evaporator embodied therein similar to the one shown in Figure l.

Referring to Figures l and 2 of the drawings, the evaporator is shown as consisting essentially of a metallic cylinder 1 having heads 2 and 3 at the upper and lower ends thereof respectively. The upper head 2 may be provided with" a thermometer well, as shown at 4 and has inlet pipes 5 and 6 eX- tending therethrough as shown. rlhe lower head 3 is provided with an outlet pipe 7 and may also be provided with a drain plug as shown at 8.

Each of the inlet pipes 5 and 6, which extend into the evaporator through the upper head 2, terminate a short distance above the bottom of a cup, these cups being shown in the drawings as 9. The cups 9 may be of any suitable shape adapted to hold liquid and are welded or otherwise rigidly secured to the walls of the evaporator near the upper end thereof,

Below each cup there is. a series of "tatie plates l0 arranged one above the other as shown in Figure l, For holding these baffles and thecups 9 in position a number of rings 10, the outer diameter of which is to the inner diameter of the outer shell l, may he welded or otherwise secured to each pair plates so as to properly the same and provide means for mounting the plates the outer shell of the evapo lil@ rator.. The rings 10 should have a water tight joint with the plates 10.

As shown more particularly in Figure 2, the plates 10 are not complete disks but their horizontal surfaces are, in general, segments of a circle. That is, they are of the Shape of the portion of a circle` bounded by an are and a cord. Each pair of plates being in ahorizontal plane, and being diametrically separated, an open space extending longitudinally through the evaporator, is provided. The inner edge of each plate, along the cord referred to above, is turned upwardly to provide a lip for retaining a liquid on the upper surface of each baile plate. These lips are shown as 11.

Each plate 10 is also provided with an aperture 12 to permit liquid to drain from it to the next lower plate of the series. A flange 13 is struck up adjacent each aperture, a distance slightly less than that of the lip 11 so as to provide a proper overiiow for each plate. The apertures on the successive plates' of any one series are staggered in relation to each other so that the overflow from one plate will fall onto the plate beneath. This staggered relation is indicated in Figure 2, the dotted lines indicating the apertures on the plates beneath the ones shown in full lines.

A hole 14 is drilled nea-r the top of each cup 9 for providing an overflow for the cup. With this construction it will be seen that liquid refrigerants entering the evaporator through the inlet pipes and 6 will fill the cups 9 up to the overflow holes 14 from which they will trickle down over the baflie plates 10. So long as the refrigerants trickling down over the plates remain in the liquid phase they will not mix with one another but both will be exposed to the vapor phase of the other so that evaporation can take place. If, for example, ammonia is entering the evaporator through the inlet pipe 6 and propane through the pipe 5, simultaneous evaporation of both will take place to a large degree, both iluids exerting their vapor pressure independently. The gases or vapors thus formed may pass downwardly through the central portion of the evaporator and out through the'pipe 7. Any portion of the liquids which are not evaporated on the plates will likewise be carried away through this pipe. Figures 3, 4 and 5 show a modilied form of cup construction which may be substituted for any pair of baille plates and a cooperating ring 10 of the evaporator of Figure 1. The cup shown in these figures comprisesl a disk shaped bottom portion 15 and an upstanding wall portion 16. The bottom portion has three apertures therein, one of which is located centrally of the bottom as shown at 17 and the other two of which are located radially from the center at different distances as shown at 18 and 19. An

upstanding ilange is provided adjacent each of these apertures as shown at 20, 21, 22 respectively, the flange 20 being slightly higher than the flanges 21 and 22. A partition 23, of the same height as the flange 20 divides the lower portion of the cups into two compartments.

The upper edge of the wall 16 of the cup is provided with two diametrically dis osed notches 24 while the lower and outer e ge of the bottom is provided with similarly disposed lugs or projections 25. With this construction, when a plurality of the cups are assembled the lugs 25 may be caused to interit with the notches 24 on the next cup of the series and hold the cups in the proper angular relation. Although all of the cups are identical in construction they may be so assembled that the apertures 18 and 19 are alternately on one side and then the other. It willl be obvious to those skilled in the art that this same result might be obtained by positioning the apertures 18 and 19 the same distance from the center of the cup but offset similar to the positioning lof the apertures 12 of Figure 2. In this way if one cup is turned 180 from the position of the next succeeding one the proper staggering of the apertures may be obtained.

Figure 6 shows a modified form of evaporator in which the cups 9 are dispensed with, the pipes 5 and 6, being reversely bent as shown at 5 and 6 to provide liquid seals therein. By this means, liquidcolumns may form in these pipes just as they do in the preferred construction.

Figure 7 is a diagram showing how the evaporators described above may be incorporated in a continuous absorption refriger-0 ating system using ammonia and propane as refrigerants. For a full disclosure of the system shown in this ligure, reference may be had to the copending application of Stanley R. Cummings, Serial No. 423,075, tiled January 24, 1930, wherein this system is more fully disclosed and claimed. As herein shown, the system includes a lgenerator G, a rectifier R, condensers C1 and C2, evaporator E and an absorber-separator S as essential elements, these vessels being connected by suitable conduits as shown.

The generator G is preferably provided with a gas lift pump similar to that shown in U. S. patent to Altenkirch 1,728,742 for circulating an absorption liquid between the generator and the separator S.' The rectifier R may be of any suitable construction for removing water vapor expelled with the ainmonia from the generator G. In the form shown it is provided witha series of apertured baflies or plates.

rlhe condensers C1 Land C2 may consist of standard condensing coils immersed in a tank 31 of cooling water. The condenser C2 is preferably the larger of the two so as to cause the temperature on the inside thereof to be more nearly equal to that of the cooling water in the tank 31.

The evaporator designated at E may be of 10 at 32 for causing ammonia and propane gases which enter at the bottom of the vessel through the pipe 33 to be broken up or divided into small bubbles so as to facilitate complete absorption of the ammonia constituent. The vessel S is provided with two chambers 34 and 35 on the outside thereof, surrounding the lower and upper portions respectively. The lower chamber 34 is a cooling chamber and is connected by the pipes 36, to the cooling jacket 31 for the condensers. The upper chamber 35 is for heating the upper portion of the vessel S and is connected with the boiler and the heat exchanger 37 by the pipes 38 and 39.

As stated above, this system is designed for the use of two refrigerants, as for example ammonia and propane. The generator G andseparator S also contain a quantity of water for absorbing the ammonia. rlhe operation of the system is as follows Ammonia is expelled from the generator G by the vapplication of heat to the lower end thereof and passes up through the rectifier R into the condenser C1 where its is liquefied and passes into the evaporator E. At the same time propane which is collected in liquid form in the top portion of the vessel S is heated by the warm solution from the boiler which passes through the heating `chamber 35 and into the heat exchanger. Heating the liquid propane causes it to pass into the condenser C2 in vapor form where it is condensed and likewise fed into the evaporator E. The total pressure in 7the evaporator E is substantially the same as that in the remainder of the system except for the difference due to the liquid columns in the pipes 5 and 6. Since the total pressure in the evaporator is equal to the sum of the partial pressure due to propane vapor and the partial pressure due to ammonia vapor, however, both refrigerants will evaporate. The

mixture of ammonia and propane vapor passes downwardly through the pipe 7 into the lower portion of the vessel S where the ammonia is absorbed by the circulation of absorption solution therethrough and since this portion of the vessel is maintained at a relatively low temperature by the tank 34, the gaseous propane being freed from ammonia condenses and rises to the top portion of the vessel S where it is again heated and driven off, thus completing the propane cycle. rlhe ammonia which is absorbed in the absorption solution is drawn into the generator by the gas lift pump 30 where it is again driven 0E to complete its cycle. rfhe gas lift pump 30 causes a circulation of the absorption solution from the generator through the pipe 38 and the heating chamber 35, the pipe 39, the outer'portion of the heat exchanger 37 and into the separator S where it is again drawn into the generator. It will be noted that the separator S has three functions; that of absorbing the ammonia, that of liquefying the propane and separating it from the ammonia in liquid phase and the driving off of propane from the upper portion. Since propane is practically immiscible with the ab- Y sorption solution and with ammonia and is lighter, it is separated from these fluids by gravity.- Practically pure propane is thus delivered to the condenser C2. This is necessary to proper operation of the apparatus for if ammonia collects in the condenser .C2 the vapor therein becomes the same as that in the evaporator, propane ceases condensing and the apparatus stops functioning. While only a few embodiments of the evaporator have been shown and described in this application it will be obvious to those skilled in the art that various changes might be made without departing from the spirit of the invention and the scope of the annexed claims.

l claim 1.. An evaporator for refrigerating systems comprising a vessel having a plurality of inlet pipes and an outlet pipe connected thereto, means in said vessel for causing'fluids supplied through said inlet pipes to remain separated from one another so long as they are in the liquid phase while permitting the fiuids to mix freely therein after they have evaporated and means for forming a liquid seal at a lower end of said inlet pipes.

2. An evaporator for refrigerating systems including a vessel, means for feeding a plurality of fluid refrigerants into said vessel in y liquid phase, means for preventing said uids from mixing therein so long as they are in the liquid phase and for accelerating the evaporation thereof by exposing each refrigerant to thevapor phase of another and means for conducting the fiuids in vapor phase out of said vessel.

3. An evaporator for refrigerating systems including a vessel, a plurality 0f cups in said vessel, means for supplying. liquid refrigerants to said cups and for causmg the same to overflow, a plurality of horizontally disposed plates arranged in series beneath each of said cups to catch the overflow therefrom and keep the refrigeranteh separated' so long as they are in liquid phase to thereby cause evaporation of the refrigerants as they trickle down over the outer surfaces of the Walls'of the Cups and over said plates.

4. Means for producing a cooling effect comprising the combination of a plurality of- A fluid refrigerants and a plurality ofisupports for` holding portionsl of said refrigerantsin liquidphase adjacent to but not mixed wlth one vanother to thereby expose a portion of one refrigerant in liquid phase to the vapor phase of another to accelerate evaporation thereof 5. Apparatus for producing a cooling eff ect comprising the combination of a vessel, a plurality of fluid refrigerants thereln and means for holding portions of said refrigerants in liquid phase in separated parts of said vessel and for causing the mixing of portions of said refrigerants in vapor phase to thereby cause evaporation of the portions of the refrigerants in liquid phase.

6. In a refrigerating system, a vessel, a plurality of inlet pipes for feeding a plurality of liquid refrigerants into said vessel, an outlet pipe connected to said vessel, a plurality of plates mounted in said vessel beneath said inlet pipes and having means thereon for causing the liquid ref-rigerants-supfplied thru said inletpipes yto remain separated from one another' as they trickle down over said plates, said plates being so disposed as to permit 'the refrigerants to mix freely in said vessel after they have evaporated. f

7 In a refrigerating system, aY vessel, means for-feeding 'a' plurality of liquid refrigerants into said vessel and.; plates `arranged in substantially:horizontal position in said vessel and forming a plurality ofsupports for said liquid. refrigerants forholding the same separated substantially throughout said vessel.

8. vIn a refrigerat-ing system, the combination of a vessel, means for feeding a plurality of liquid refrigerants into said vessel and means for causing liquid refrigerants Jfed into said vessel to remain separatedin a por tion thereof but each exposed to the vapor phase of theother whereby both refrigerante masy evaporate in said vessel. v

lgned at North Canton, in the county of Stark, and State of Ohio, 1930.

RUDOLPH S. NELSON.

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