US2229687A - Refrigeration - Google Patents

Description

Filed Dec. 18, 1936 lllllllllllllillllllll WEIIVENTOR.

6 Maxi:

ATTORNEY.

Patented Jan. 28, 1941 UNITED STATES REFRIGERATION Albert R. Thomas, Evansville, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application December 18, 1936, Serial No. 116,489

more particularly to a refrigeration system making use of evaporation of refrigerant in the presence of an inert gas. q It is an object of the invention to provide improved circulation and gas and liquid contact in M refrigeration apparatus as will appear from the following description and accompanying drawing in which-the single figure shows more or less diagrammatically a refrigeration system embodying the invention.

, Referring to the drawing, the system is made up of a number of steel vessels and pipes welded together to form a hermetically sealed system. All spaces of the system are in open and unrestricted communication so that all parts are at the same total pressure. The system contains hydrogen and a water solution of ammonia. Other suitable alternative fluids may be used. A vertical conduit I0 is connected at its lower end to the outer passage ll of a liquid heat exchanger l2. The upper end of conduit I0 is provided with heat radiation fins l3 for air cooling. Alongside of the vertical conduit H3 is a narrower riser M. The lower part of the riser I4 is formed as a coil l5.' The lower end of the coil i5 is connected to-the inner passage N5 of the liquid heat exchanger i2, and the upper end of the riser ie is connected to the vertical conduit ID at a point just below the heat radiation fins I3. The coil I5 is heated, as by a burner ll. The lower part of the vertical conduit lfl may also be heated by the burner H. The internal cross-section of the riser l4 and the coil I5 is sufiiciently small that gas and liquid cannot pass each other therein (disregarding surface film) so that vapor formed by heating of. liquid in the coil 1 5 becomes trapped in the liquid and causes liquid to rise through the riser l4 into the vertical conduit 10. The lower part of the vertical conduit l0 may be referred to as a generator, or the lower part of the conduit III, the coil l5, and the riser It may be collectively referred to as a generator. In the generator, ammonia vapor is expelled by heat out of the water solution. Thevapor rises into the upper end of the vertical condui It provided with the air cooled fins !3. This part of the vertical conduit Ill may be referred to as a rectifier. Here water vapor having a higher condensation temperature than ammonia vapor is condensed out and flows back into the generator.

An evaporator l8 comprises a pipe coil constructed and arranged so that liquid entering the upper end flows downward and is distributed throughout the length of the coil. The rectifier I3 is connected to one end of a condenser l9. The other end of the condenser is connected to the upper end of the evaporator l8. Ammonia vapor flows from the rectifier 13 into the con- 5 denser I9 where it is condensed to liquid. The condensed ammonia drains from the condenser into the upper end of the evaporator l8 and flows" downward therein in the presence of hydrogen I which flows upward through the evaporator l8. '1 The liquid ammonia evaporates and difiuses into the hydrogen producing refrigeration effect. 7

The upper end of the evaporator coil !8 is connected by a conduit 20 to the inner passage 2| of a gas heat exchanger 22. The lower end of 15 the inner passage 2| is connected by a conduit 23 to a sump vessel 24. The lower end of the evaporator I8 is connected to the upper end vof the outer passage 25 of the gas heat exchanger 22. The lower end of the outer passage 25 is 20 connected by a conduit 26 to a vessel 21. The lower part of vessel 21 is connected by a downwardly looped conduit 28 to the lower part of a vessel 29. A substantially horizontal conduit 30 has one end connectedto the vessel 29 and the 25 other end connected to the vessel 24. The con duit 30 is provided on its exterior with heat radiation fins 3| and on the interior is provided with bafies 32.

The lower part of vessel 24 is connected by a 30 conduit 33 to the inner passage 16 of the liquid heat exchanger 12. The outer passage ll of the liquid heat exchanger i2 is connected by a conduit 34 to a circulation vessel 35 located above the vessel 21 but slightly below the level'of the 35 point at which the riser l4 discharges into the vertical conduit III of the generator. The bottom of the vessel 35 is connected by a downcomer 36 to the vessel 27; The downcorner 35 extends into the vessel 2! and is open at its lower end therein. 40 The downcomer36 is provided with heat radiation fins 31 and its internal diameter is sufiicient- 1y small that gas and liquid cannot pass each other therein so that liquid entering this conduit will trap beneath it any gas which is in the 45 conduit.

The upper part of vessel 29 is connected by a conduit 38 to the upper part of the vessel 35. The conduit 34 may be provided with heat radiation fins 39 for air cooling of liquid in this con- 50 duit. There is also provided a small liquid trap -drain conduit so for conducting excess liquid from the lower end of the evaporator coil l8 into the inner passage 2| of the gas. heat exchanger 22. 65

The operation of the system is as follows: Rich gas, formed by evaporation of ammonia into hydrogen in the evaporator 18 as previously described, flows from the upper end of the evaporator l8 through conduit 20, inner passage 2| of the gas heat exchanger 22, and conduit 23 into the absorber sump vessel 24. The gas then flowsv through conduit 30 into vessel 29 and thence through conduit 38 into the circulation vessel 35. Liquid is delivered into the circulation vessel 35 through conduit 34 and drops downward through conduit 36 into the lower vessel 21. The liquid descending through conduit 36 carries with it gas and vapor which becomes trapped below the liquid so that gas and vapor is drawn into vessel 35 from conduit 38 and discharged into the lower vessel 2! whence the gas returns through conduit 26 and outer passage 25 of the gas heat exchanger 22 to the lower end of the evaporator l8.

Liquid which is discharged into the vertical conduit ID of the generator accumulates in the U-trap formed by the vertical conduit l0,.outer passage ll of the liquid heat exchanger l2, and conduit 34, until the surface level of liquid in this U-trap reaches the point of overflow from conduit 34 into the circulation vessel 35. The liquid which flows downward through conduit 36 collects in vessels 21 and 29, the horizontal conduit 30, and vessel 24 until it reaches a surface level sufficient to form a column of liquid which balances the lighter column of liquid and gas in the generator coil l5 and riser l4. Liquid flows from the absorber sump vessel 24 through conduit 33 and the inner passage [6 of the liquid heat exchanger l2 back to the generator coil l5 from where it is lifted through riser l4 into the vertical conduit ID as previously described.

Due to the expulsion of ammonia vapor from solution in the generator, the liquid which overflows through conduit 34 into the circulation vessel 35 is referred to as weak or weakened absorption solution. The weakened absorption solution is brought into contact with gas during descent through conduit 36 and is again brought into contact with gas in the horizontal conduit 30. The weakened absorption liquid in contact with the gas absorbs ammonia vapor out of the gas and becomes enriched so that the liquid which flows from the absorber sump 24 through conduit 33 back toward the generator is referred to as strong or enriched solution.

Gas flowing from the eevaporator l6 through conduit 20 toward the absorber vessel 24 contains a relatively high concentration of ammonia vapor and this gas is referred to as strong or rich gas. The rich gas passing first through conduit 30 in contact with solution is deprived of some of its ammonia vapor. It then comes into further contact with absorption solution in the downcomer or fall-tube 36 where it is deprived of a further amount of ammonia vapor before returning to the evaporator. Thus, the gas returning to the evaporator is referred to as poor or weakgas.

In the circulation of fiuids described above, the strong gas comes into contact first with strong solution in the horizontal conduit 30 and the resulting weaker gas then comes into contact with weakened absorption solution in the down comer 36. The heat of absorption is dissipated to air by the heat radiation fins 3i and 31 on conduits 30 and 36 respectively. Other cooling media for these conduits may be provided. The amount of solution placed in the system is sufiicient so that the surface level of liquid in conduit 30 is at least up to the upper parts of the baflles 32 in the horizontal conduit 30, so that gas passing through this conduit must bubble through the liquid beneath these baiiles thus bringing the gas and liquid into intimate contact. The previously described circulation arrangement provides the necessary force for causing this bubbling of gas through liquid without any mechanical moving parts such as fan, blower, or injector and without any unbalanced liquid columns.

Let us assume that the relative circulation of liquid is about 10 kilograms of weak solution for each kilogram of ammonia evaporated in the evaporator l3 and the circulation of gas is about 3 kilograms of weak gas per kilogram of ammonia evaporated. .The ratio of weak gas volume to weak liquid volume is then about 20 to 1. If, for example, the downcomer 36 is 21 inches long, a

one inch slug of liquid falling through the length of conduit 36 would trap 20 volumes of weak gas and carry this gas out of conduit 36 to a pressure equal to 1 inch of liquid. This is suflicient to bubble the gas through, for instance, one half an inch of liquid in the absorber conduit 30 and make available another one half inch of liquid pressure to overcome resistance in the gas circuit.

The drawing shows the system more or less diagrammatically and it will be understood that various alterations may be made in the parts of the apparatus shown and additions made within the scope of the invention. For examples: The evaporator l6 may be constructed as described in U. S. Patent 2,008,343 or U, S. Patent 2,057,408; the conduit from the condenser l9 to the evaporator l8 may be formed to provide a liquid seal as described in U.,S. Patent 1,620,843, and provided with a condenser gas vent conduit as shown in U. S. Patent 1,645,706; there may be provided a hydrogen reserve vessel or pressure vessel as described in U. S. Patent 1,822,224; the generator may be a vertical type as described in U. S. Patent 1,645,706, or it may be a horizontal type as described in U. S. Patent 1,830,302; various known rectifiers and analyzers may be provided.

It will be understood by those skilled in the art that various other changes and modifications may be made within the scope of the invention which is not limited to the embodiment shown in the drawing and described in the specification, but only as indicated in the following claims.

What is claimed is:

1. In a refrigeration system of the kind employing an inert gas for equalizing pressure, members providing a circuit for inert gas includmg an evaporator and an absorber, means to supply liquid to said circuit in such quantity as to block off free flow-of gas in the circuit and provide a body of liquid such that for gas to flow through the circuit it must flow through the body of blocking liquid, and a narrow drop tube in said circuit supplied at the top with liquid and gas for trapping gas by liquid and providing a gas propelling liquid weight, said drop tube being of such cross-section that liquid dropped therein bridges the tube from wall to wall and being of a height. to provide a force for the circulation of the inert gas sufiiciently greater than pipe resistance in the circuit to cause the gas to flow through the body of blocking liquid and circulate in said circuit, and means to supply liquid to the drop tube.

2. In a refrigerating system of the kind employing an inert gas for equalizing pressure, members providing a circuit for inert gas ineluding an evaporator and absorber situated below the evaporator, a generator, and means to circulate absorption liquid between the generator and the absorber, the absorber including a vessel adapted to hold a body of absorption liquid having a plurality of segregated surface levels and formed to block off free flow of gas in the inert gas circuit so that inert gas must pass below the liquid surface and through the body of liquid to flow from the space above one surface level to the space above another surface level, and means within the system to develop sufficient force to circulate the inert gas in the gas circuit and cause the inert gas to pass into and by liquid displacement force its way through the body of liquid in the absorber from the space above one surface level to the space above another surface level.

3. In an absorption refrigeration system of the kind employing an inert gas, members providing a circuit for inert gas including an evaporator and an absorber situated below the evaporator and a circuit for absorption liquid including the absorber and a generator, and the absorber including a horizontal conduit arranged to hold liquid in a quantity suflicient to block oil" free flow of gas in the inert gas circuit, means to circulate absorption liquid between the generator and the absorber and cause flow of liquid in one direction in the horizontal conduit, and means to circulate inert gas in the gas circuit and cause the inert gas to pass into and by liquid displacement force its way through liquid in the horizontal conduit in a direction opposite to the flow of absorption liquid, said last-mentioned means being operative by circulation of fluid in the system.

4. In a refrigerating system employing inert gas and including an inert gas circuit, means to supply absorption liquid in the circuit in such quantity as to block oil free flow of gas in the circuit, said liquid blocking portion of said circuit being constructed and arranged to provide a plurality of partially segregated pools of liquid disposed substantially horizontally with respect to each other, and structure embodied in the system to cause the inert gas to circulate in the gas circuit and bubble in said partially segregated pools of liquid to force its way through the blocking liquid, thereby agitating the blocking absorption liquid at the liquid surface level.

5. In an absorption refrigeration system of the kind employing an inert gas, a circuit for inert gas including an evaporator and an absorber, a circuit for absorption liquid including said absorber, said absorber including a conduit located substantially in a horizontal plane and arranged to hold liquid in a quantity that blocks free flow of gas therein whereby gas flowing in said gas circuit has to pass through liquid in said liquid circuit by bubbling through liquid with the absorber in a generally horizontal direction, means to cause flow of liquid in said liquid circuit, and

means to cause flow of gas in said gas circuit and supplying suflicient pressure to cause gas to pass into and by liquid displacement force its way through liquid in the generally horizontal conduit of said absorber.

6. An absorption refrigeration system as set forth in claim 5 in which said last means is a fall tube gas pump constructed and arranged to be operated by a liquid in said liquid circuit and in a manner such that a small quantity of liquid causes flow of a large volume of gas.

ALBERT R. THOMAS.

CERTIFICATE OF CORRECTION. 7 Patent No. 2,229, 6 7. January 28, 19t

ALBERT R. THOMAS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correctiona s follows: Page 2, sec- 0nd column, line 1+5, for the patent number "l,850,502"read -.1,85Q,205--; and that the said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 11,1111 day of March," A. D. 19m.

. Henry Ven Arsdale, (-Seal) 1 2 Acting Commisei'oner of Patents.

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