US3583177A - Two-stage absorption machine with first stage generator outside the main shell - Google Patents

Abstract

The structural relationship of the two-stage generator absorption refrigeration machine having two shells is disclosed. A primary shell contains a low pressure generator, a condenser, an evaporator, and an absorber. A separate shell contains the high pressure generator.

Description

United States Patent [56] References Cited UNlTED STATES PATENTS 6/1964 Kaufmanet [72] Inventor John L. M. Holman Onalaska, W's. 802,706

3,398,548 8/1968 Cox et al....... 3,452,551 7/1969 Aronson........ 3,266,266 8/1966 Reid,Jr.

[21 Appl. No.

[22] Filed Dec. 20, 1968 [45] Patented June 8, 1971 [73] Assignee The Trane Company La Crosse, Wis.

FOREIGN PATENTS 12/1965 Canada..........

Primary Examiner-William E. Wayner Attorneys-Arthur 0. Anderson, Lee E. Johnson and Carl M.

parate Lewis ABSTRACT: The structural relationship of the two-stage 62/487 generator absorption refrigeration machine having two shells is disclosed. A primary shell contains a low pressure genera- 62/489, tor, a condenser, an evaporator, and an absorber. A se 479, 497 shell contains the high pressure generator.

2 0 l 5 3 b 5 2 F [54] TWO-STAGE ABSORPTION MACHINE WITH FIRST STAGE GENERATOR OUTSIDE THE MAIN SHELL 1 Claim, 4 Drawing Figs.

[51] Int.

[50] Field of PATENTEUJUH 812m 3.583177 sum 1 BF 2 INVENTOR.

JOHN L M. HOLMAN 82 73 74 ATTORNEY PATENTED JUN 8 I971 SHEET 2 OF 2 TORNEY TWO-STAGE ABSORPTION MACHINE WITH FIRST STAGE GENERATOR OUTSIDE THE MAIN SHELL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a refrigeration machine, and more particularly to a two shell, two stage generator, absorption refrigeration machine.

2. Description of the Prior Art Prior absorption refrigeration machines have usually employed only a single stage generator or concentrator. As the absorption refrigeration technology has advanced, it has been realized that more efficient use of the heat input to such a refrigeration machine can be made by incorporating an additional generator. Two generators are staged to produce a multiple effect machine. Heat from a source such as high pressure steam is supplied to a first stage generator and is returned to the steam source. Refrigerant vapor liberated from boiling absorbent in the first stage is fed to a heat exchanger in the second stage generator. This vapor condenses in a heat exchanger causing partially concentrated absorbent solution in the second stage to boil, thus further concentrating that solution. The condensate and the vapor are both fed to a condenser section for cooling and condensing.

Since the first stage generator is operating at a much higher pressure than the remainder of the absorption machine, it is desirable to separate this portion of the cycle from the remainder of the machine. In addition, if all five sections of the absorption cycle were to be placed in a single shell, the final product would become much larger than present single stage absorption refrigeration machines of comparable capacity.

SUMMARY OF THE INVENTION This invention therefore provides an absorption refrigeration machine comprising: a first fluidtight shell enclosing an evaporator section which contains a chilled medium heat exchange means; the chilled medium heat exchange means adapted to be connected to an area being cooled; an absorber section containing a first cooling medium heat exchange means, the first cooling medium heat exchange means adapted to be connected to a source of cooled fluid, the absorber section in vapor communication with the evaporator section; a low pressure generator section containing a refrigerant vapor heat exchange means, the refrigerant vapor heat exchange means containing a vapor trap means for only allowing passage of liquid refrigerant, the low pressure generator section separated from the evaporator and the absorber sections by a fluidtight wall; a condenser section containing a second cooling medium heat exchange means, the second cooling medium heat exchange means adapted to be connected to a source of cooled fluid, the condenser section in vapor communication with the low pressure generator section and in liquid communication with the evaporator section and in fluid communication with the vapor trap means; a second fluidtight shell enclosing a high pressure generator section containing a heated medium exchange means, the heated medium heat exchange means adapted to be placed in communication with a source of heat energy, the high pressure generator section in liquid communication with the absorber section and in vapor communication with the refrigerant vapor heat exchange means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front view of the two-shell absorption refrigeration machine of the present invention.

FIG. 2 is a rear view of the absorption refrigeration machine of FIG. 1.

FIG. 3 is a view of the absorption refrigeration machine of FIG. I in which the front tube sheets ofthe two shells and the external piping have been omitted.

FIG. 4 is a side view of the main shell taken along section 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring jointly to FIGS. 1, 2, and 3, the absorption refrigeration machine comprises a first fluidtight shell 10 which encloses a condenser section 12, an evaporator 14, an absorber l6, and a second stage generator, low pressure 20. A second fluidtight shell 35 encloses the first stage, high pressure generator 18.

The absorber I6 has a heat exchanger, comprising longitudinally extending tubes 22, which is supplied with cooling fluid from a source not shown through header 24. Connection with the conduit from the cooling fluid source is made with flange 25. Header 24 supplies all of tubes 22. The cooling fluid, which can be water which is evaporatively cooled by air, is conducted from header 33 by conduit 26 from the rear of the heat exchange tubes 22 to a header 27 which supplies heat exchange tubes 28 in condenser 12. Connection of conduit 26 with headers 33 and 27 is made by means of flanges 32 and 34, respectively. A wall 29 substantially encloses the condenser section. The cooling fluid leaves the condenser though header 30 and returns to the cooling fluid source via a conduit (not shown) connected to flange 31. It is understood of course, that any of a variety of connections may be made with the heat exchangers of this machine without departing from the inventive concept; for example, heat exchangers 22 and 28 can be independently connected to a source of cooling fluid and each can be altered to produce a two-pass effect.

High pressure steam, or other heating medium, flows from a source such as a boiler (not shown) into header 51 by connection with flange 36. The steam flows from header 52 into heat exchange tubes 37 in high pressure generator 18. End plate 38 has a dual function; it serves not only as the end plate which seals the ends of shell 35, but also is the tube sheet for heat exchange tubes 37. End plate 39 serves the same purpose at the opposite end of the generator 18 and additionally provides connection with conduit 40. Heat exchange tubes 37 terminate within end plate 39 and in fluid communication with header 4]. A restrictor means is normally attached to flange 42 to prevent escape of steam from the heat exchange tubes 37 until it has condensed, allowing substantially only condensate to leave heat exchange tubes 37. This restrictor means can be any suitable steam flow restrictor such as an orifice or a float valve. Alternatively, the restrictor can be mounted within the generator 18. Heat from condensing steam in the heat exchange tubes 37 causes dilute absorbent solution present in the first stage generator to boil. The steam condensate from the aforementioned restrictor means flows back to the steam generating source. It is to be understood, of course, that a combustible fluid, direct fired, heat exchange or other suitable energy source can be substituted for the heat exchange tubes 37 without substantially modifying the principals of construction of this invention.

Various types of refrigerants and absorbents may be used in the present machine. A solution oflithium bromide absorbent in a refrigerant such as water is satisfactory. The term concentrated solution as used herein means a solution which is concentrated in an absorbent. A weak solution" is a solution dilute in absorbent. A solution having a concentration between that of a concentrated solution and a weak solution is termed an intermediate strength solution.

The refrigerant vapor generated in the first stage generator 18 flows through conduit 40 and into the second stage low pressure generator 20. Conduit 40 is connected to flanges 52 and 53, the latter of which allows access to header 43. The refrigerant vapor flows from header 43 into heat exchange tubes 44. The refrigerant vapor condenses and releases heat to further concentrate intermediate strength solution present in the second stage generator 20. A flow regulating device in the form of an orifice or a trap 45 regulates the flow of refrigerant from the heat exchange tubes 44 into the condenser I2.

Trap 45 is connected with heat exchange tubes 44 via header 46 onto which it is attached at flange 47. Condensed refrigerant from heat exchanger tubes 44 enters the condenser at a connection 48 above header 30. The difference in pressure between the condenser and heat exchange tubes 44 forces the condensed refrigerant from the tubes 44 into the condenser 12. Trap 45 functions to prevent flow of any refrigerant vapor from heat exchange tubes 44 into the condenser 12. The vapor produced from the boiling intermediate strength solution in the second stage generator passes through eliminators 49 where it is condensed into a liquid in condenser 12. Eliminators 49 remove entrained liquid from the vapor. Liquid refrigerant flows from the condenser through opening or orifice 50 into evaporator 14.

The liquid refrigerant is evaporated in evaporator 14, thus removing heat from the fluid in heat exchange tubes 61. The refrigerant vapor produced passes through eliminators 62 to remove entrained liquid and into the absorber section 16. Unevaporated liquid refrigerant is collected in pan 60, from which it enters conduit 63, and is recirculated by pump means 64 through conduit 65 into spray header 66. From header 66 the liquid refrigerant is sprayed over heat exchange tubes 61 through spray nozzles 67. Fluid from a heat load is circulated through heat exchange tubes 61 by connection with flanges 70 and 71 on headers 69 and 68 respectively. The fluid circulated through heat exchange tubes 61 is cooled by the evaporating refrigerant. It is thereafter returned to the heat load.

Absorbent solution present in absorber 16 absorbs refrigerant vapor produced in evaporator 14. The solution from the absorber 16 flows through a conduit 72 in the bottom of the absorber section. The absorbent solution from conduit 72 is circulated by pump 73 through conduit 74, a low temperature heat exchanger 75, a high temperature heat exchanger 76, and conduit 77 from which it enters high pressure generator l8.The absorbent solution flowing into generator 18 is partially concentrated therein.

The partially concentrated solution from high pressure generator 18 flows through conduit 78 to high temperature heat exchanger 76 in which it gives up heat to weak solution flowing into conduit 77. It then flows through conduit 79 into low pressure generator 20, in which it is further concentrated. The concentrated solution from the second stage generator 20 flows through conduit 80, through low temperature heat exchanger 75 into conduit 81 which is connected to the inlet of pump 82. Dilute solution flowing from absorber 16 through conduit 83 also enters the inlet of pump 82 where it is mixed with the concentrated solution flowing from conduit 81. The weak and concentrated solutions are mixed in pump 82 and are forced through conduit 84 to spray header 85, from which it is distributed over heat exchange tubes 22 by spray nozzles 86.

It will be understood by one skilled in the absorption refrigeration art that motive power is necessary to drive pumps 64, 73, and 82. The preferred power source is, of course, an electric motor. Each pump can be driven by a separate motor, or a single motor can be employed to drive all pumps with a single shaft.

Referring now to FIGS. 3 and 4, the internal arrangement of the components sections of the absorption machine will be further described. The numerals in FIG. 4 correspond to those utilized in the preceding figures. High temperature generator 18 can have a length equal to that of main shell 10. ln this embodiment generator shell 35 has an upper circular section and a lower liquid tank section 91. Partially concentrated absorbent solution is collected in tank 91 before it flows into conduit 78. Refrigerant vapor produced in high pressure generator 18 flows through opening 54 into conduit 40. Intermediate strength flows into low temperature generator 20 through conduit 79. Concentrated solution flows out of low temperature generator 20 through weir 92 into compartment 93. From this compartment the concentrated absorbent solution flows into conduit 80. Compartment 93 can extend the full length of the shell 10. More than one weir 92 can be employed, or the weir 92 can extend the full length of the shell 10. The liquid eliminators 49 are a series of spaced parallel plates positioned as shown in FIG. 3 so that the leading edge of one plate overlaps the trailing edge of a next adjacent plate. This construction provides a tortuous path for refrigerant vapor entering the condenser which facilitates removal of entrained liquid refrigerant.

It will be noted that all of the heat exchange tubes are longitudinally extending relative to the main shell 10 and genera tor shell 35. The end plates 94 and 95 attached at the end of shell 10 serve a dual function. They seal and form the end portions of the various compartments within the shell. Furthermore, teat exchange tubes extend through to the outside of end plates 94 and 95. Thus the end plates form the tube sheets for all of the heat exchangers in primary shell 10. The headers 24, 27, 30, 33, 43, 46, 68, and 69 are then mechanically attached to these end plates for distributing the various fluids through the heat exchange tubes.

The absorber section 16 is in vapor communication with the evaporator section 14. Condenser 12 is in liquid communication with the evaporator section 14 through the orifice 50. The condenser 12 receives refrigerant liquid from heat exchange tubes 44 via connection 48 and is also in vapor communication with the low pressure generator 20 through liquid eliminators 49. The relative arrangement of the sections as shown in H6. 3 are preferred, that is, the low pressure generator and condenser substantially horizontally contiguous in the upper portion of the main shell, the absorber in the lower portion of the main shell, and the evaporator above the absorber. The high pressure generator is located to provide a liquid level therein above any liquid level existing in the main shell. However, other arrangements of the low pressure generator, the condenser, the evaporator, and the absorber within the main shell 10 can be made without departing from the present invention. Of course, the shells 10 and 35 need not be of the cylindrical cross section as shown. They may be of any desired cross section; however, the cylindrical shape is most desirable.

Of course, flow, pressure, safety, and miscellaneous control are necessary for proper operation of the absorption refrigeration machine disclosed above. For an example of an appropriate control mechanism for the instant machine, refer to the copending application, Ser. No. 785,51 I, filed Dec. 20, I968, incorporated herein by reference.

The utility and need for the absorption refrigeration machine of this invention are apparent from the foregoing description. Therefore, what I claim is:

1. An absorption refrigeration machine comprising first and second fluidtight shells; said first shell including an evaporator section containing a chilled medium heat exchange means adapted to be connected to an area to be cooled; an absorber section below said evaporator section and in vapor communication therewith, said absorber section containing a heat exchange means adapted to be connected to a source of cooled fluid; a low pressure generator section containing a refrigerant vapor heat exchange means communicating with a vapor trap means for allowing passage of only liquid refrigerant therethrough, said low pressure generator section separated from said evaporator section and said absorber sec tion by a fluidtight wall; and a condenser section containing a heat exchange means adapted to be connected to a source of cooled fluid, said condenser section located above said evaporator section and said absorber section and in fluid communication with said vapor trap means, in vapor communication with said low pressure generator section, and in liquid communication with said evaporator section; said second shell including a high pressure generator section containing a heat exchange means adapted to be connected to a source of heat, said high pressure generator section being in vapor communication with said low pressure generator section and in liquid communication with said absorber section; said second shell being located sufficiently above said first shell to insure that the liquid level in said second shell is above any liquid level in said first shell during operation of said refrigeration machine.

Claims (1)

1. An absorption refrigeration machine comprising first and second fluidtight shells; said first shell including an evaporator section containing a chilled medium heat exchange means adapted to be connected to an area to be cooled; an absorber section below said evaporator section and in vapor communication therewith, said absorber section containing a heaT exchange means adapted to be connected to a source of cooled fluid; a low pressure generator section containing a refrigerant vapor heat exchange means communicating with a vapor trap means for allowing passage of only liquid refrigerant therethrough, said low pressure generator section separated from said evaporator section and said absorber section by a fluidtight wall; and a condenser section containing a heat exchange means adapted to be connected to a source of cooled fluid, said condenser section located above said evaporator section and said absorber section and in fluid communication with said vapor trap means, in vapor communication with said low pressure generator section, and in liquid communication with said evaporator section; said second shell including a high pressure generator section containing a heat exchange means adapted to be connected to a source of heat, said high pressure generator section being in vapor communication with said low pressure generator section and in liquid communication with said absorber section; said second shell being located sufficiently above said first shell to insure that the liquid level in said second shell is above any liquid level in said first shell during operation of said refrigeration machine.

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