US3928983A

US3928983A - Method of producing cold in an absorption-type refrigerating plant performing this method

Info

Publication number: US3928983A
Application number: US490864A
Authority: US
Inventors: Emmanuil Gershkovich Ainbinder; Georgy Vasilievich Kurilov; Leonid Sergeevich Neustroev
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-11-26
Filing date: 1974-07-22
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30

Abstract

A method and apparatus for causing refrigeration use an absorbent which is directed in a primary flow for regeneration into a zone where it is superheated with a high-temperature heat transfer medium; the pressure within this zone is raised to prevent boiling-up of the superheated absorbent; the latter is returned from the superheating zone in a counterflow in respect of the primary relatively cold flow of the absorbent toward the superheating zone; the pressure of the return flow is reduced in a step-wise fashion in successive stages of the flow, the pressure being reduced in each said stage so as to ensure momentary boiling-up of the absorbent at the given respective temperature thereof. In each of the stages the coolant vapor produced is made to condense with transfer of heat to the adjacent relatively cold flow of the absorbent on its way to the superheating zone. The apparatus includes a multi-stage regenerator, wherein each of the stages is made up by a pack of perforated plates, the pressure reduction stages being grouped into two separate sections.

Description

tlnite States Patent Ainbinder et al.

[ Dec. 30, 1975 METHOD OF PRODUCING COLD IN AN ABSORPTION-TYPE REFRIGERATING PLANT PERFORMING THIS METHOD {76] Inventors: Emmanuil Gershkovich Ainbinder,

bulvar Pushkina, 7, kv. 8; Georgy Vasilievich Kurilov, ulitsa Universitetskaya, 97, kv. 21; Leonid Sergeevich Neustroev, ulitsa Artema, 127, kv. 42, all of Donetsk, U.S.S.R.

[22] Filed: July 22, 1974 {21] Appl. No.: 490,864

Related U.S. Application Data [63] Continuation of Ser. No. 424,737, Dec. 14, 1973, abandoned, which is a continuation of Ser. No. 331,358, Feb. 12, 1973, abandoned, which is a continuation of Ser. No. 204,108, Dec. 2, 1971, abandoned.

[52] U.S. C1. 62/101; 62/476; 62/497;

[51] Int. Cl. FZSB 15/06 [58] Field of Search 62/101, 109, 476, 497;

[56] References Cited UNITED STATES PATENTS 3,146,177 8/1964 Chalmers et al 202/173 X 3,228,859 1/1966 Frankel et a1. 159/2 MS 3,287,928 11/1966 Reid, Jr. 62/476 X 3,306,346 2/1967 Othmer 62/101 X Primary Examiner william 1F. ODea Assistant ExaminerPeter D. Ferguson Attorney, Agent, or FirmHolman & Stern [57] ABSTRACT A method and apparatus for causing refrigeration use an absorbent which is directed in a primary flow for regeneration into a zone where it is superheated with a high-temperature heat transfer medium; the pressure within this zone is raised to prevent boiling-up of the superheated absorbent; the latter is returned from the superheating zone in a counterflow in respect of the primary relatively cold flow of the absorbent toward the superheating zone; the pressure of the return flow is reduced in a step-wise fashion in successive stages of the flow, the pressure being reduced in each said stage so as to ensure momentary boiling-up of the absorbent at the given respective temperature thereof. 1n each of the stages the coolant vapor produced is made to condense with transfer of heat to the adjacent relatively cold flow of the absorbent on its way to the superheating zone. The apparatus includes a multi-stage regenerator, wherein each of the stages is made up by a pack of perforated plates, the pressure reduction stages being grouped into two separate sections.

8 Claims, 4 Drawing Figures l7 2/ 26 r 74 I A 2W r J US. Patent Dec.30, 1975 Sheet1of2 3,928,983

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US. Patent Dec.30, 1975 Sheet2of2 3,928,983

na U III:

METHOD OF PRODUCING COLD IN AN ABSORPTION-TYPE REFRIGERATING PLANT PERFORMING THIS METHOD This is a continuation, of application Ser. No. 424,737, filed Dec. 14, 1973, now abandoned which in turn is a continuation ofSer. No. 331,358 filed Feb. 12, 1973, now abandoned, which in turn is a continuation of Ser. No. 204,108 filed Dec. 2, 1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a methods and apparatus for producing cold temperatures and refrigeration, and, more particularly, the invention relates to absorption-type lithium bromide refrigerating plants employing high-temperature heat transfer media as the source of heat.

2. Description of Prior Art It is widely known that the existing absorptionftype lithium-bromide refrigerating plants operate with extraction of the condensation and absorption heat with the help of water derived from water supply. Therefore, when large refrigerating plants of this type are constructed and operated, the problem of providing therein either recycled or flowing-through cooling water involves relatively great capital investment and a high operation cost, which makes the aim of cutting down the consumption of cooling water by lithium absorption-type refrigerating plants a truly pressing one.

At present, efforts aimed at cutting down the consumption of recycled water by lithium bromide absorption-type refrigerating plants are concerned with reducing the thermal load of the condenser, e.g. by introducing double-stage regeneration and by stepping up the overall temperature level of heat extraction, for instance, by employing multi-stage systems.

Known solutions of the above said problem improve the economical features of the plant, but they however necessitate extraction of the condensation heat from the coolant being condensed into the ambient atmosphere consequently, greater the economical characteristic of their operation, the smaller is (under comparable conditions) the difference between the temperature of the medium being cooled and that of condensation.

It should be also stated here that the existing systems of both recycled and flow-through cooling water supply involve not only wastage of considerable quantities of water, but also the waste of a huge amount of lowpotential heat.

A number ofindustries that consume artificial cold at temperatures above 0C, such as metallurgical, chemical, cokechemical, petro-chemical, meat-processing, dairy, food-industries, etc. offer a considerable amount of waste heat in the form of hot chimney gases at temperature of about 300 to 400C, as well as in theform of coke-oven gas, blast-furnace gas and other combustible gases, or else they operate on natural gas.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of producing cold and an absorption-type refrigerating apparatus which utilises high-temperature heat, the apparatus being capable of round-the-year operation for production of artificial heat and of hot 2 water for technological and sanitary purposes. In the refrigeration plant described and claim herein, the lower the temperature of the water being cooled, the higher the economical characteristic of the operation of the plant (under comparable conditions).

It is another object of the present invention to create a method of causing refrigeration and an absorptiontype lithium bromide refrigerating plant, which employs high-temperature heat and operates without the use of recycled water from water supply, but with the use of air-cooling, and with or without the employment of an intermediate heat transfer medium.

It is also an object of the present invention to provide a method of refrigeration and an absorption-type plant that employs high-temperature heat and is capable of replacing the cooling systems for recycled water supply in industrial enterprises, the absorption type plant described herein is capable of replacing heat-supply boilers for production of either hot or superheated water.

It is yet another object of the present invention to broaden the field of applications of absorption-type lithium-bromide refrigerating plants, by utilizing them for generation of low temperatures either below or approximating 0C.

The present invention attains these and other objects and resides in a method of causing refrigeration and cooling, comprising the steps of absorbing the vapor of a coolant, evaporating subsequently said coolant from the absorbent, directing said absorbent into a superheating zone with the help of a high-temperature heat transfer medium, raising the pressure within said zone to prevent boiling-up of said superheated absorbent, reducing said pressure in a step-wise fashion in successive stages at successive portions of the flow of said absorbent starting from the superheating zone, the pressure in each said stage being reduced so as to provide for momentary boiling-up of said superheated absorbent at the respective given temperature thereof, the method being characterized in that said superheated absorbent is returned from said superheating zone in a counterflow in respect of the primary flow of said absorbent toward said superheating zone, so that the vapor of said coolant produced at each stage of said return flow condenses and effects heat transfer within said stage to the adjacent relatively cold primary flow of said absorbent toward said superheating zone.

In accordance with the invention, the primary flow of the absorbent may include independent successively supplied flows of absorbent that have absorbed the coolant vapor at different pressures.

In accordance with a preferred embodiment of the invention, said absorbent is an aqueous solution of lithium bromide, and said coolant is water.

In accordance with the present invention, an absorption-type refrigerating plant performing the abovedescribed method includes an evaporator of the coolant, the vapor of said coolant being absorbed in an absorber by a liquid absorbent, said liquid absorbent being subsequently directed into a regenerator subdivided into a plurality of stages wherein the pressure is reduced in a step-wise fashion, starting from the superheating zone, the plant being, characterized by said regenerator having therein a plurality of passages for the passage therethrough of the primary flow of said absorbent toward said superheating zone, and also for the passage of the return flow of said superheated absorbent flowing in a counterflow in respect of said primary flow, as well as a plurality of passages for the passage of the condensate, there being provided at the successive portions of said return flow passages and condensate passages means for reduction of the pressure, said pressure-reducing means subdividing said regenerator into said Stages, each said stage, starting from said superheating zone, communicating with the next successive stage for separately directing thereinto said absorbent and said condensate.

In accordance with an embodiment of invention, the plant described herein has said pressure-reducing means in the form of hydraulic seals.

In accordance with one of the embodiments ofthe invention, each said stage of said regenerator plant includes a pack of assembled plates separated by gaskets and having apertures made therethrough, these apertures serving together with said passages for the passage of the above heat transfer media and said condensate.

In a plant embodying the invention said hydraulic seals between said stages may include each a gasket defining on the adjacent extreme one of said plates a vertical conduit establishing communication between the respective pair of said adjacent stages, the height of said vertical conduit determining the value of the pressure drop between said stages. A plant embodying the invention, when it includes different absorber means adapted to absorb the vapor of said coolant at different pressures, may have said regenerator thereof so constructed that said stages thereof are grouped into two separate sections, the second one of said sections in the direction of the flow of said absorbent which is regenerated being included into the flow path of said primary flow intermediate of said absorber means, the first one of said sections communicating with that one of said absorber means which is operated at a relatively higher pressure.

The above improvements ensure elimination of the aforesaid drawbacks of the prior art refrigerating plants.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be further described in connection with a preferred embodiment thereof, with reference being had to the accompanying set of drawings, wherein:

FIG. 1 shows a schematic diagram of a plant embodying the invention, wherein heat extraction is performed with the help of an intermediate heat transfer medium;

FIG. 2 shows a schematic diagram of a plant embodying the invention, wherein heat is extracted from the apparatus directly into ambient air;

FIG. 3 shows a schematic diagram of a refrigeration plant embodying the invention, adapted to produce cold at temperatures about and below zero degree centrigrade; 7

FIG. 4 illustrates the regenerator of the plants shown in FIGS. 1 to 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the embodiment of the present invention illustrated in FIGS. 1 to 4 various specific terms and expressions are used for the sake of clarity; however, the invention is in no way meant to be limited by these specific terms and expressions which are understood to embrace all the equivalents thereof operating in a similar manner and used for purposes similar to those of the present invention. The apparatus to be described hereinbelow can be employed for operation of the plant, as a whole, in accordance with any one 'of the diagrams illustrated in FIGS. 1 to 3; the switchingover from the operating mode to another being effected by correspondinng re-connection of the solution conduits establishing communication between the apparatus.

Referring now in particular to the appended drawings, generation of low temperatures by refrigeration is effected within an evaporator l. The evaporator l incorporatesheat exchange tubes 2 and a sprinkler device 4; it is associated with a pump 3. Extraction of heat from the coolant circulating in the form of the refrigerant is effected within the tubes 2.

This extraction of "heat from the coolant is brought about by evaporation of recirculation water supplied by the pump 3 and'sprinkled over the tubes 2 of the evaporator l.

The water vapor thus produced passes into an absorber 5 wherein it is absorbed by the relatively rich solution of an absorbent, sprinkled by a sprinkler device 6 over heat exchange tubes 7.

The solution of the absorbent, which is diluted because of reduced concentration on account of absoption of the coolant vapor, is fed from the absorber 5 by a pump 8 for regeneration into a heater 9 through the passages 10 of a regenerator 11. In order to prevent boiling-up of the solution within the passages 10 and in the heater 9, the diluted solution is supplied for regeneration under gauge pressure which is above the saturation pressure of the solution at the outlet of the heater.

The solution of the absorbent after being heated up is fed through a throttling device 12 into the passsages 13 of the regenerator 11, the passages being meant for the flow of the superheated absorbent.

' The regenerator 11 also includes passages 14 for collection and removal of the condensate produced on account of evaporation of the return flow of the absorbent through the passages 13.

The

passages

13 and 14 are divided by respective throttling devices into a plurality of successive portions (i.e. stages) for rapid boiling-up of the return flow of the absorbent, with corresponding stage-wise reduction of the pressure thereof, the coolant vapor produced in each of the stages condensing with transfer of heat into the relatively cold initial flow of the absorbent through the passages 10.

Owing to the repeated boiling-up, the concentration of the absorbent in the return flow is increased.

The richer solution of the absorbent is fed from the outlet stage, i.e. from the last boiling-up stage of the regenerator 11 through a heat-exchanger 15 into an absorber 16.

The absorber 16 is meant for absorption of the water vapor coming from an evaporator 19. Thelatter effects extraction of heat from the absorber 5 by evaporation of water pumped through the tubes 7 of the absorber 5, this water being distributed in the evaporator 19 by a sprinkler device 21. The pressure within the evaporator 19 is higher than that within the evaporator 1, whereby the pressurewithin the absorber 16 is higher than the pressurewithin the absorber 5. Therefore, in the following part of the disclosure the absorber 16 and the evaporator 19 will be referred to as the high-pressure apparatus, while the absorber'S and'the evaporator 1 will be "referred to as the low-pressure apparatus".

The heat exchanger 15 effects cooling down of the rich-concentration solution of the absorbent to a temperature approximating the absorption temperature within the absorber 16. i

The absorbent solution the concentration of which has been partly reduced within the absorber 16, is fed by the pump 22 for cooling down in a heat-exchanger 23, where from it is directed into the absorber 5. Within the absorber 5 the absorbent solution performs is absorbing action at a pressure that is lower than that within the absorber 16. lt absorbs the coolant vapor produced within the evaporator 1 from the recirculation water, as heat is being extracted from the heatedup cold transfer medium.

The evaporators 1 and 19 are associated with means for directing thereinto the condensate from the regenerator ll.

For extraction of heat from the plant shown in FIG. 1 there is provided a water cooling device 24.

Water cooled down in the water cooling device 24 is pumped for heat extraction by a pump 25 through the heat-exchanger 23, through the tubes 18 of the absorber l6 and through the heat-exchanger l5, whereafter it returns into the water cooling device 24. Cooling air is blown through the water cooling device 24 by a separately provided blower or fan means (not shown in FIGS. 1 to 3).

The absorber l6 and the heat exchangers l5 and 23 may have direct air cooling as is shown in FIG. 2. In this case these apparatus are associated either with individual air blower means or with a common one, for extraction of heat (the air blower or fan means are not shown in FIG. 2), and the apparatus per se is either of a multitube or of a finned plate structure, i.e. the apparatus includes a developed surface for contact with the cooling air.

When a plant embodying the present invention is to be operated for producing temperatures below 0C or temperatures approximating 0C (see FIG. 3), the regenerator 11 is sub-divided into two sections A" and B, to be connected to accomodate the primary flows of the absorbent through the passages of these sections A and B, respectively, to the low-pressure absorber 5 and to the high-pressure absorber 16. The return flow of the absorbent, that successively passes through the boiling-up stages of the passage 13 of the sections A and B, is cooled within the heatexchanger to a temperature approximating the initial temperature of absorption within the absorber 5. The absorbent solution the concentration, of which has been brought down in the absorber 5, is pumpedby the pump 8 into the passages 10 of the section B of the regenerator 11, wherein it is heated up by the condensation heat of the vapor of the coolant which is vaporized in the passages 13 of this section of the regenerator l 1.

In order to prevent freezing'of the recirculation water and of the cold transfer medium, when the herein disclosed plant is operated to produce temperatures below zero, the recirculation water is replaced either by'an alkaline solution (such as KOH or LiOI-l), or else by a weak solution of LiBr.

The coolant condensate is returned into the evaporators (see FIGS. 1 to 3) through loop-type hydraulic seals 26 and 27. The condensate from the regenerator 11 is directed into the evaporator 19, wherefrom it is directed into the evaporator l.

The

abovementioned passages

10, 13 and 14 of the regenerator 14 are defined by a series of similar parts, illustrated in greater detail in FIG. 4. v

Boiling-up of the return flow of the absorbent solu' tion takes place in hollow closed passages 28 including: a conduit 29 for the passage therethrough of the initial poor-concentration solution of the absorbent, a conduit or pipe 30 for producing a hydraulic seal in each successive evaporation panel relative to the preceding one, a cap member, or conduit 31 for producing a downflow of the boiling-up solution, an aperture a for removal of the coolant vapor produced, an aperture b for introduction of the return flow of the absorbent into the pipe 30, an aperture c for removal of the boiled-up absorbent solution.

Condensation of the coolant vapor takes place over the surface of the pack of plates associated with the evaporation panel through a gasket 32. The pack of plates is made up by plates 33, 34 and gaskets 35, 36.

The plates 33 and 34 have the following apertures made therethrough:

' aperture a for the passage of the coolant vapor;

aperture c for removal of the boiled-up absorbent solution;

aperture e for removal of the condensate;

aperture d for the passage of the primary poor-concentration flow of the absorbent.

The

gaskets

32, 35 and 36 are provided with apertures a, c, e, d formed therethrough and arranged continuously with the similarly designated apertures in the plates 33 and 34.

Condensation of the coolant vapor takes place in a space defined by the panel 28, the gasket 32 and the plate 33, as well as by the-adjacent plates 34 and gaskets 35. The passage of the vapor is ensured by the provision in each of the above members of the aperture a. The extraction of the condensation heat of the coolant vapor is effected into the flow of the absorbent through the space between the plates 33 and 34, defined by the gasket 36.

The coolant condensate is directed through the respective apertures e in the above plates and gaskets toward the blind wall of the next successive return flow evaporation panel 28. Supply of the condensate into the next successive condensation stage is effected through a hydraulic seal provided by a gasket 37 defining together with the last-in-the-series plate 33, i.e. with the plate 33 adjoining the next successive panel 28, a vertical passage establishing communication between the adjacent stages through the conduit 31.

The vertical extent or reach of the last-mentioned vertical passage determines the pressure drop between the adjacent stages, because, on account of the density of the absorbent solution being substantially higher than the density of the coolant, the hydraulic seal of the conduit 30 can be selected to provide for a greater pressure drop between the adjacent stages 'than the pressure drop effected by the above hydraulic seals and affecting the condensate. The passages of the regenerator 11 (FIGS. 1 to 3) are thus defined by the assembly of the abovedescribed structural parts illustrated in FIG. 4.

The passage 10 for the primary flow of the absorbent is defined by the conduit 29 continuous with the apertures d in the gasket 32 and in. the plate 33, by the gaps defined between the adjacent plates 33 and 34 by the gasket 36, by the apertures d in the bottom right-hand corners of the plate 34, gasket 35 and plate 34 adjacent to the last-mentioned gasket on the side of the return flow, by the next successive gap between the plates 34 and 33 and the gasket 36, by the apertures d in the upper left-hand corners of the plate 33 and in the gas ket 32 interposed between this plate 33 and the successive panel 28, by the conduit 29 in the panel 28. Thus, the conduit 29 provides for the passage of the primary flow from the passage of one stage of the regenerator 11 into the passage 10 of the next successive stage, in the direction of the primary flow.

The passage for the return flow of the absorbent is made up by the aperture b in the panel 28, by the conduit 30, by the internal cavity of the panel 28, by the apertures c in the

gaskets

32, 35, 36 and in the plates 33, 34 associated with the panel 28, by the aperture b in the next successive panel 28, by the conduit 30 in the last-mentioned panel, and so on, until from the panel 28 which is the last in the succession in the direction of the return flow the rich-concentration solution of the absorbent is directed toward the high pressure absorber 16.

The passage 14 for collection and removal of the condensate is defined by the wall of the panel 28 with the aperture a, by the adjacent gasket 32, by the plate 33, by the apertures e in the plates 33 and 34, by the apertures e in the gaskets 36 and by the space defined by the gasket 37 in the gap between the blind wall of the next successive return flow evaporation panel 28 and the plate 33 adjacent thereto. Through said passage 14 the condensate is supplied toward the conduit 31 which directs it into the next successive condensation stage.

The abovedescribed sets of the evaporation panels, gaskets and plates, shown in FIG. 4, are assembled into packs, or stacks.

Production of cold temperature in the herein disclosed plant, with the employment of an intermediate heat transfer medium for extraction of heat from the apparatus, as shown in FIG. 1 of the appended drawings, is effected in the following way.

Within the tubes 2 of the evaporator 1 heat is extracted from the water that has been heated up, in the consumer of cold by the recirculation water sprinkled over the tubes 2. Thus, the heat supplied to the recirculation water from the consumer of cold is partly spent on evaporation of the last-mentioned water. The water vapor thus produced (i.e. the coolant vapor) is absorbed by the absorbent solution, which is an aqueous solution of a relatively rich concentration, within the absorber 5. Absorption of the water vapor by an aqueous solution of lithium bromide (LiBr) takes place when there is a definite positive difference between the water vapor pressure in the evaporator 1 and in the absorber 5, in the absence of non-condensible gases.

As a result of the absorption of the water vapor, the absorbent solution is heated up, and the concentration, thereof diminishes, whereby it becomes incapable of absorbing water vapor at the pressure within the absorber 5.

Extraction of the heat of the absorption of the cool water vapor from the low-pressure evaporator 1 is effected in the high-pressure evaporator 19 by evaporating of the water recirculated through the coiled tubes 7 of the absorber 5 sprinkled with a LiBr solution.

The poor concentration solution is directed from the absorber 5 (the concentration being, e.g. 54% 56% at a temperature of 30 to 40C) under a high pressure into a superheating zone, for the supply thereto of the heat necessary ,for increasing the concentration of the solution by evaporation of the coolant that has been absorbed within the absorbers 5 and l6.

The superheating zone is formed by the passage 10 of the regenerator 11 (FIG. 1 to 3), the heater 9 and the throttling device 12. At this zone, the solution is first heated to -lOOC within the passage 10, whereafter it is heated to 200230C within the heater 9 and reduced into the superheated condition in the throttling device 12. The superheated return flow of the absorbent solution is introduced into the first panel 28 through the conduit 30. Boiling-up of the solution in the evaporation panels is determined by the condensation pressure of the coolant vapor in the passage 14 adjoining the panels (FIGS. 1 to 3). The condensation pressure in the passages 14 is determined by the number of the stages of evaporation of the solution, by the heat exchange conditions and by the initial temperature of the primary flow of the solution, fed into the passage 10.

The partly strengthened solution is directed from the abovementioned panel 28 through a passage formed by the apertures in the adjacent plates and gaskets (see above) into the conduit 30 of the next successive panel 28. The conduit 30 acts as a hydraulic seal along the line of the return flow of the solution between each successive evaporation stage in relation to the preceding one.

Condensation of the vapor takes place in the passages 14 (FIGS. 1 to 3) over the surface of the adjacent pairs of the plates 33 and 34 (FIG. 4), with the condensation heat being turned over to the primary flow of the relatively weak solution directed under pressure between the said plates toward the heater 9.

The condensate from each section of the evaporation (condensation) stage, i.e. the condensate produced on account of evaporation of the coolant from the return flow of the absorbent solution, is collected adjacent the successive panel 28 through the corresponding apertures (see above) in the pack of the plates and gaskets and is directed into the successive stage through the passage formed by the adjacent plate 33, gasket 37, panel 28 and conduit 31. This passage acts as a hydraulic seal of each evaporation stage in relation to the preceding one along the condensate flow line.

It should be noted here that it is possible to replace the conduits 30 in the panels 28 by conduits similar to those effecting direction of the condensate, and it is also possible to replace the evaporation panels themselves by two plates and one gasket per each panel.

As a result of self-evaporation of the return flow of the absorbent, as it passes successively from a preceding evaporation panel into a successive one at a pressure that is reduced stage-wise, in accordance with the temperature of the condensation of the vapor in each respective stage of the regenerator 11, and of condensation of the coolant vapor by the relatively cool primary flow of the absorbent solution pumped through the passages 10 (FIGS. 1 to 3), there is effected regeneration of the initially relatively weak absorbent solution flow without the employment of an external cooling medium for condensation of the coolant vapor.

This means that the operation of the regenerator 11 is more economical (under comparable conditions), with the cold temperature produced being simultaneously brought down, because the temperature of the weak solution taken from the absorber 5 and directed into the passage 10 of the regenerator 11 is reduced. The reduction of the initial temperature of the primary flow of the solution at the inlet of the passage 10 leads to broadening of the degassing zone, thereby causing 9 increase in the cold temperature produced. The strengthened solution of LiBr from last-in-the-succession panel 28 (along the return flow of the absorbent) and the condensate from the pack of the plates and gaskets adjacent to this panel are directed, respectively as follows:

the LiBr solution through the heat exchanger 15 where it is cooled by 20C 30C into the absorber 16;

the condensate into the evaporator 19 through the loop-type hydraulic seal.

The strengthened solution flows into the absorber 16 through the heat exchanger 15 by gravity, owing to the regenerator l 1 being positioned above the absorber 16. Within the latter the LiBr solution absorbs water vapor at a relatively high pressure from the evaporator 19. The absorption heat of the coolant vapor is extracted by the water circulated through the tubes 18 sprinkled with the solution. The weakened LiBr solution is subsequently supplied by the pump 22 into the absorber 5, for absorption of the low-pressure coolant vapor. Prior to being fed into the absorber 5, the solution is cooled in the heat-exchanger 23 by 20 to 30C.

After having passed through the hydraulic seal into the evaporator 19, the condensate from the regenerator ll boils up and cools down to a saturation temperature within this evaporator 19. A portion of the condensate, necessary for maintaining a permanent level of the recirculation water in the evaporator 1, is directed into the latter through the loop-type hydraulic seal. In this way the closed flow of the coolant in the herein disclosed plant is completed.

The removal of the heat supplied to the herein disclosed plant in the evaporator and in the heater is effected:

in the heat exchanger 15 at temperatures of the solution within 1 10 to 80C;

in the absorber 16 at solution temperatures within 80 to 70C;

in the heat exchanger 23 at solution temperatures within 70 to 45C.

The extended range of the temperatures of the heat removed from the herein disclosed plant and the possibility of withdrawing not less than 70 percent of this heat at temperatures above 70C in the herein disclosed plant offer a wide variety of applications involving simultaneous production of cool and hot water for practical purposes.

In addition to the abovementioned heat exchangers l and 23, the line along which the LiBr solution is supplied into the absorber 5 and into the passage of the regenerator 11 may be associated, for the sake of greater economy, with other auxiliary means for cooling down the solution, e.g. those employing air or water, and those .using air cooling combined with water evaporation, etc. (these auxiliary cooling means are not shown in FIGS. 1 to 3).

The operation of the herein disclosed plant without the use of the intermediate heat transfer medium for heat extraction, illustrated in FIG. 2, is basically similar to that described hereinabove. However, in the plant shown in FIG. 2 heat is extracted from the plant directly into the ambient atmosphere at the finned tubes of the

heat exchangers

15, 23 and of the absorber 16.

When the plant is operated according to the mode illustrated in FIG. 2, the heat extracted therefrom can be utilized only in the form of hot air at temperatures 60 to 70C. Therefore, in cases when it is desirable to produce refrigeration or cold temperature and also to satisfy customers in need of heat at temperatures from C to 100C, it is advisable to employ the plant in accordance with FIG. 1. Alternatively, when either the use of the extracted heat is impractical, or when there are consumers of hot air, it is advisable to employ the plant illustrated in FIG. 2.

When the plant is operated for production of cold temperatures either below or approximating 0C (FIG. 3), there is used in the evaporator 1 either a weak alkaline solution (KOH, Lioll-l) or a weak solution of LiBr as the recirculation medium, instead of water, and the sections A and 13" of the regenerator 11 are connected in series, as far as the return flow of the absorbent solution being strengthened and the flow of the coolant condensate are concerned, these sections A and B being connected in parallel in respect of the primary flow of the weak, relatively cool absorbent, namely:

the section A is connected to the low-pressure absorber 5; the section B is connected to the high-pressure absorber 16.

Now the circulation of the LiBr solution through the system is as follows: low -pressure absorber 5 pump 8 passage 10 of section A of regeneration l1 heater 9 throttling device 12 passage 13 of regenerator 11 heater l5 absorber 5. Similarly to the abovedescribed operation mode, the absorption heat of the low-pressure vapor from the evaporator l is firstly extracted by evaporation of water in the evaporator 19 and secondly, by absorption of the thus produced vapor in the high-pressure absorber at a higher temperature level. The condensate from the regenerator 11, as it has been mentioned hereinabove, is directed into the evaporator 19, wherefrom it is directed into the evaporator l for completing the closed path of the coolant within the plant.

In this case the heat removed from the consumer of cold and that supplied to the heater is extracted in two regions of the apparatus, namely:

in the heat exchanger 15 at solution temperature within 100C 45C;

in the absorber 16 at solution temperature within 60 to C.

The withdrawal of air and of uncondensible gases from the herein disclosed plant is performed in the following sequence: from the absorber 5 into the absorber l6 and then into the atmosphere. Withdrawal of air from the regenerator-condenser line is effected by blowing through the condensation sections into the evaporator 12. Means for withdrawing uncondensible gases are not shown in FIGS. 1 to 3.

It should be borne in mind that the embodiment of the invention described hereinabove and illustrated in the appended drawings is but an exemplary embodiment; other embodiments and variations of the present invention are also possible and envisaged, differing from the one described herein by the structure of individual apparatus, by the solution circulation path, by the distribution of the solution among the absorbers, by the employment of circulated water in the evap'orators, by the path of circulation of the cooling water through the absorbers and evaporators.

The structure of the hereinabove described regenerator can likewise be modified without departing from the scope of the invention, e.g.. the structure may incorporate various regulators at different levels instead of the hydraulic seals, said regulators being associated with automatic means for withdrawal of the solution and of the condensate from stages preceding the last one, should be temperature of the solution at the inlet of the regenerator-condenser fall below a preset value. Furthermore, the plates used may be of various shapes and structures, special portions for flushing the vapor by the condensate may be provided within the evaporation panels, and so on. Such modifications are possible, if the following principal condition is satisfied: evaporation of the solution should be effected at a pressure that is reduced stage-wise, and the vapor is condensed at the weak solution directed in a counter-flow in respect of the solution being strengthened.

Plants constructed in accordance with the present invention can be employed for operation with various absorbents that are non-covaporizable with the solvent, and the heat extracted from the plant may be used for various purposes, including simple heating of various media and various processes, such as vacuum deaeration of water.

As follows from the above disclosure, the expression absorption type refrigeration plant that is used in the claims to follow is intended to include such equivalent as thermo-chemical compressor, thermal transformer, heat-utilization plant, etc. that can be operated on the principle of the present invention.

What we claim is:

1. A method of producing low temperatures and causing refrigeration, comprising the steps of:

absorbing the vapor of a coolant with a liquid absorbent;

directing said absorbent into a primary flow into a superheating zone thereof with the help of a hightemperature heat transfer medium under a high pressure;

maintaining the high pressure within said superheating zone to prevent boiling-up of the superheated absorbent; reducing the pressure in' a step-wise fashion in successive stages at successive portions of the flow of the absorbent, starting from the superheating zone, the pressure in each stage being reduced so as to provide for a momentary boiling-up of said superheated absorbent at a respective given temperature thereof; returning said superheated absorbent from said superheating zone in counterflow heat exchange with the primary flow of said absorbent toward the superheating zone so that the vapor of said coolant produced at each stage of said return flow condenses and effects heat transfer inside the stage with respect to the cold primary flow of absorbent toward said superheating zone; and I returning the coolant condensate to an evaporator with a subsequent evaporation thereof at a low temperature due to the heat extracted from the object to be cooled and by absorbing the cold vapors with the liquid absorbent which is to be cooled by an outside source.

2. A method in accordance with claim 1, wherein said primary flow of said absorbent includes independent successively supplied flows of absorbent that have absorbed said vapor of said coolant at different pressures.

3. A method in accordance with claim 2, wherein said absorbent is an aqueous solution of lithium bromide and said coolant is water.

4. An absorption-type refrigerating plant using a coolant comprising:

evaporating means for evaporating the coolant;

absorbing means communicating through a vapor space to said evaporating means for absorbing the vapor of said coolant with a liquid absorbant;

an absorbent regenerator subdivided by a throttle into an absorbent superheating zone under a high pressure and stages for successive step-wise reduction of the pressure of said superheated absorbent, said regenerator communicating in a primary flow and a return'flow with said absorbing means, said regenerator having a plurality of successive passages for the passage therethrough of the primary flow of said absorbent towards said superheating zone, an additional passage for the passage therethrough of the return flow in successive stages of said superheated absorbent directed in a counterflow to the primary flow, and a plurality of passages for the flow of a condensate;

means provided at said successive stages of said return flow passage and at least some of said condensate passages for reducing the pressure of said return flow of absorbent and said condensate, said means subdividing said regenerator into said successive stages, each stage starting from said superheating zone being associated with a successive one of said stages for a separate passage of said absorbent and said condensate;

pipes for returning the coolant condensate to said evaporating means for a subsequent evaporation thereof at a low temperature due to the heat extracted from the object being cooled and for returning the coolant vapor to said absorbing means, pipes for returning of strengthened absorbant to absorbing means of the vapor of said collant; means for cooling the liquid absorbant; and means for heat exchange between the vapor of said coolant of return absorbent flow and said primary absorbent flow.

5. A refrigerating plant in accordance with claim 4, wherein said means for pressure-reducing comprise hydraulic seals.

6. A refrigerating plant in accordance with claim 5, wherein each said stage of said regenerator includes a pack of plates separated by gaskets and having apertures made therethrough, said apertures making up together said passages for the passage of said primary and said return flows and of said condensate.

7. A refrigerating plant according to claim 6, wherein each of said stages includes a gasket defining on an adjacent extreme one of said plates conjugated with the blind wall of an evaporating panel, a vertical conduit communicating with each other a pair of said adjacent stages and having a predetermined height, the height of said vertical conduit determining the value of the pressure drop between said adjacent stages.

8. An absorption-type refrigerating plant using a coolant, comprising:

evaporating means for evaporating the coolant;

absorbing means communicating through a vapor said superheating zone being associated with said regenerator having a plurality of successive passages for the passage therethrough of a primary flow of said absorbent to said superheating zone, an additional passage for the passage therethrough of a return flow in successive stages of said superheated absorbent directed in a counterflow to the primary flow, and a plurality of passages for the flow of a condensate;

means provided at said successive stages of said return flow passage and said plurality of condensate passages for reducing the pressure of said return flow of absorbent and said condensate, said mean subdividing said regenerator into said successive stages, each stage starting from said superheating zone being associated with a successive one of said stages for a separate passage of said absorbent and said condensate; and means for heat-exchange between the vapor of said coolant of return absorbent flow and said primary absorbent flow;

said regenerator comprising stages thereof which are grouped into first and second sections, the second one of said sections being disposed in the primary flow on the flow path of the regenerated absorbent from absorbing means which is operated at relatively low pressure to absorbing means which is operated at a relatively higher pressure, the first one of said sections being coupled to said absorbing means which is operated at a relatively higher pressure.

Claims

1. A method of producing low temperatures and causing refrigeration, comprising the steps of: absorbing the vapor of a coolant with a liquid absorbent; directing said absorbent into a primary flow into a superheating zone thereof with the help of a high-temperature heat transfer medium under a high pressure; maintaining the high pressure within said superheating zone to prevent boiling-up of the superheated absorbent; reducing the pressure in a step-wise fashion in successive stages at successive portions of the flow of the absorbent, starting from the superheating zone, the pressure in each stage being reduced so as to provide for a momentary boiling-up of said superheated absorbent at a respective given temperature thereof; returning said superheated absorbent from said superheating zone in counterflow heat exchange with the primary flow of said absorbent toward the superheating zone so that the vapor of said coolant produced at each stage of said return flow condenses and effects heat transfer inside the stage with respect to the cold primary flow of absorbent toward said superheating zone; and returning the coolant condensate to an evaporator with a subsequent evaporation thereof at a low temperature due to the heat extracted from the object to be cooled and by absorbing the cold vapors with the liquid absorbent which is to be cooled by an outside source.

4. An absorption-type refrigerating plant using a coolant comprising: evaporating means for evaporating the coolant; absorbing means communicating through a vapor space to said evaporating means for absorbing the vapor of said coolant with a liquid absorbant; an absorbent regenerator subdiviDed by a throttle into an absorbent superheating zone under a high pressure and stages for successive step-wise reduction of the pressure of said superheated absorbent, said regenerator communicating in a primary flow and a return flow with said absorbing means, said regenerator having a plurality of successive passages for the passage therethrough of the primary flow of said absorbent towards said superheating zone, an additional passage for the passage therethrough of the return flow in successive stages of said superheated absorbent directed in a counterflow to the primary flow, and a plurality of passages for the flow of a condensate; means provided at said successive stages of said return flow passage and at least some of said condensate passages for reducing the pressure of said return flow of absorbent and said condensate, said means subdividing said regenerator into said successive stages, each stage starting from said superheating zone being associated with a successive one of said stages for a separate passage of said absorbent and said condensate; pipes for returning the coolant condensate to said evaporating means for a subsequent evaporation thereof at a low temperature due to the heat extracted from the object being cooled and for returning the coolant vapor to said absorbing means, pipes for returning of strengthened absorbant to absorbing means of the vapor of said collant; means for cooling the liquid absorbant; and means for heat exchange between the vapor of said coolant of return absorbent flow and said primary absorbent flow.

8. An absorption-type refrigerating plant using a coolant, comprising: evaporating means for evaporating the coolant; absorbing means communicating through a vapor space to said evaporating means for absorbing the vapor of said coolant with a liquid absorbent at different pressures; an absorbent regenerator subdivided by a throttle into an absorbent superheating zone under a high pressure and stages for successive step-wise reduction of the pressure of said superheated absorbent, said superheating zone being associated with said regenerator having a plurality of successive passages for the passage therethrough of a primary flow of said absorbent to said superheating zone, an additional passage for the passage therethrough of a return flow in successive stages of said superheated absorbent directed in a counterflow to the primary flow, and a plurality of passages for the flow of a condensate; means provided at said successive stages of said return flow passage and said plurality of condensate passages for reducing the pressure of said return flow of absorbent and said condensate, said mean subdividing said regenerator into said successive stages, each stage starting from said superheating zone being associated with a successive one of said stages for a separate passage of said absorbent and said condensate; and means for heat-exchange between the vapor of said coolant of return absorbent flow and said primary absorbent flow; said regenerator comprising stages thereof which are grouped into first and second sections, the second one of said sections being disposed in the primary flow on the flow path of the regenerated absorbent from absorbing means which is operated at relatively low pressure to absorbing means which is operated at a relatively higher pressure, the first one of said sections being coupled to said absorbing means which is operated at a relatively higher pressure.