CN112815573B

CN112815573B - Double-heat-source-driven variable-temperature absorption refrigeration system

Info

Publication number: CN112815573B
Application number: CN202110004706.5A
Authority: CN
Inventors: 公茂琼; 白银; 鹿丁; 郭浩; 刘子健
Original assignee: Technical Institute of Physics and Chemistry of CAS
Current assignee: Technical Institute of Physics and Chemistry of CAS
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2022-04-12
Anticipated expiration: 2041-01-04
Also published as: CN112815573A

Abstract

The double-heat-source-driven variable-temperature absorption refrigeration system provided by the invention introduces a generator and an absorber with intermediate pressure on the basis of the traditional single-effect absorption refrigeration system, recovers a medium-low-temperature heat source through a medium-pressure generator, improves the concentration of a circulating working medium through the medium-pressure absorber, and greatly improves the residual heat utilization temperature span by combining a variable-temperature fractionation technology; the matching of the system and a heat source can be realized by adjusting the flow ratio of the solution entering the medium-pressure generator and the medium-pressure absorber and the intermediate pressure, and the variable working condition characteristic and the application range of the system are improved; in addition, the gas phase outlet of the medium pressure generator is connected with the medium pressure absorber, so that a rectifying device can be omitted, and the equipment volume and the cost are reduced.

Description

Double-heat-source-driven variable-temperature absorption refrigeration system

Technical Field

The invention relates to the technical field of low-temperature refrigeration, in particular to a variable-temperature absorption refrigeration system driven by double heat sources.

Background

With the rapid development of economy and industry, the consumption of global primary energy is increased year by year, and more than half of industrial waste heat is wasted in the forms of flue gas, exhaust steam, cylinder liner water, radiation and the like. The absorption type refrigerating system is a refrigerating mode which takes heat energy as drive and can convert waste heat into cold energy, and has wide application prospect in the aspect of waste heat recovery.

Waste heat discharged in industrial processes has different forms and grades, for example: the power devices such as an internal combustion engine, a diesel engine and the like have flue gas waste heat with higher temperature and middle and low temperature cylinder sleeve water waste heat at the same time. The traditional single-effect absorption refrigeration system is not suitable for recovering medium-low temperature waste heat, and waste of the medium-low temperature waste heat can be caused. Although the two-stage and multi-stage absorption system can recover low-temperature waste heat, the two-stage and multi-stage absorption system is not suitable for recovering high-temperature waste heat, and the two-stage and multi-stage absorption system has the defects of low-temperature waste heat recovery and low temperature waste heat recovery rate

Large loss, low efficiency, high equipment cost and the like. In addition, most of research contents such as a GAX system, a multi-effect system and a compression auxiliary system for improving the system performance are based on single heat source driving, and are not suitable for recycling waste heat of double heat sources. (201010225004.1) the proposed double heat source absorption chiller can recover the high temperature waste heat and the low temperature waste heat, but the system sacrifices part of the cooling capacity for increasing the solution concentration of the system; the low-temperature generator is in a high-pressure level, which is not beneficial to the recovery of low-temperature waste heat; and the high-temperature generator and the low-temperature generator are connected with the condenser, and for systems needing rectification such as ammonia water and the like, both the two generators need a rectification device, so that the increase of the equipment volume and the cost is caused.

Disclosure of Invention

In view of the above, it is desirable to provide a dual heat source driven variable temperature absorption refrigeration system having high refrigeration efficiency and capable of matching the grade and heat of the heat source.

In order to solve the problems, the invention adopts the following technical scheme:

in a first aspect, the present application provides a dual heat source driven variable temperature absorption refrigeration system comprising: a heat source flow path, a cooling medium flow path and a circulating working medium flow path,

the heat source flow path includes a first heat source and a second heat source;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises the high-pressure generator (1), the condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises the medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises the evaporator (4) and the low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through a working medium throttle valve (3) and a high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected through a low-pressure solution pump (6) and a medium-pressure solution throttle valve (11); wherein:

the first heat source enters the high-pressure generator (1) from a heat source inlet H1 to heat the circulating working medium, the temperature is gradually reduced, and then the circulating working medium flows out from a heat source outlet H2; the second heat source enters the medium-pressure generator (10) from a heat source inlet H3 to heat the circulating working medium, the temperature is gradually reduced, and then the circulating working medium flows out from a heat source outlet H4;

a cooling medium W1 in the cooling medium flow path respectively enters the condenser (2), the medium-pressure absorber (8) and the low-pressure absorber (5) to cool a circulating working medium;

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path is throttled and depressurized by the high-pressure solution throttling valve (12) to enter the low-pressure absorber (5), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, then is throttled and depressurized by the working medium throttling valve (3) to become a low-pressure two-phase working medium R2, and enters a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, and then is absorbed by the solution of the low-pressure absorber (5) to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) and enters an intermediate-pressure stage; the medium-pressure solution S2 entering the medium-pressure stage is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein the solution entering the medium pressure generator (10) is heated by the second heat source, and the resulting medium pressure dilute solution S8 is throttled down by the medium pressure solution throttle valve (11) into the low pressure absorber (5); the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the pressure is increased by the medium-pressure solution pump (9) to enter the high-pressure stage, and the working medium circulation is finished.

In a second aspect, the present application provides a dual heat source driven variable temperature absorption refrigeration system, comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the first heat source enters the high-pressure generator (1) from the heat source inlet H1 to heat the circulating working medium, the temperature is gradually reduced, then the circulating working medium flows out from the heat source outlet H2, the second heat source enters the medium-pressure generator (10) from the heat source inlet H3 to heat the circulating working medium, the temperature is gradually reduced, and then the circulating working medium flows out from the heat source outlet H4;

the cooling medium W1 in the cooling medium flow path respectively enters the condenser (2), the medium pressure absorber (8) and the low pressure absorber (5) to cool the circulating working medium;

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) to be heated and analyzed after being preheated by the high-pressure solution heat exchanger (13), a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially passes through the high-pressure solution heat exchanger (13) and the high-pressure solution throttling valve (12) to enter the low-pressure absorber (5), high-pressure steam generated by the high-pressure generator enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttling valve (3) to become a low-pressure two-phase working medium R2 which enters a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, and then is absorbed by the solution of the low-pressure absorber (5) to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) and enters an intermediate-pressure stage; the medium-pressure solution S2 entering the medium-pressure stage is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein, a part of solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by the second heat source, the generated medium-pressure dilute solution S8 sequentially passes through the medium-pressure solution heat exchanger (14) and the medium-pressure solution throttle valve (11) to be throttled and depressurized and enters the low-pressure absorber (5), the solution entering the medium-pressure absorber (8) absorbs gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the solution is boosted by the medium-pressure solution pump (9) to enter the high-pressure stage, and the working medium circulation is finished.

In a third aspect, the present application provides a dual heat source driven variable temperature absorption refrigeration system, comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the heat source flow path comprises a first heat source and a second heat source, and the first heat source outlet H2 is connected with the second heat source inlet H3;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises the high-pressure generator (1), the condenser (2) and the high-pressure solution heat exchanger (13), the medium-pressure stage comprises the medium-pressure generator (10), the medium-pressure absorber (8), the medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises the evaporator (4) and the low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through a working medium throttle valve (3) and a high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected through a low-pressure solution pump (6) and a medium-pressure solution throttle valve (11);

the heat source firstly enters the high-pressure generator (1) from the heat source inlet H1 from bottom to top to heat the circulating working medium, the temperature is gradually reduced, then the heat source flows out of the heat source outlet H2, and enters the medium-pressure generator (10) from bottom to top through the heat source inlet H3 to heat the circulating working medium, the temperature is gradually reduced, and then the heat source flows out of the heat source outlet H4;

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) to be heated and analyzed after being preheated by high-pressure solution heat exchange (13), a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially passes through the high-pressure solution heat exchanger (13) and the high-pressure solution throttling valve (12) to enter the low-pressure absorber (5), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttling valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, and then is absorbed by the solution of the low-pressure absorber (5) to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) and enters an intermediate-pressure stage; the medium-pressure solution S2 entering the medium-pressure stage is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein a part of the solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly and then enters the medium-pressure generator (10) to be heated by a heat source, and the generated medium-pressure dilute solution S8 is throttled and depressurized into the low-pressure absorber (5) through the medium-pressure heat exchanger (14) and the medium-pressure solution throttling valve (11) in sequence; the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the pressure is increased by the medium-pressure solution pump (9) to enter the high-pressure stage, and the working medium circulation is finished.

In a fourth aspect, the present application provides a dual heat source driven variable temperature absorption refrigeration system, comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1), a condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through a working medium throttle valve (3) and a high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), the medium-pressure stage and the low-pressure stage are connected through a low-pressure solution pump (6) and a medium-pressure solution throttle valve (11), a working medium subcooler (15) is further arranged between the high-pressure stage and the medium-pressure stage, and low-temperature working medium R3 from the medium-pressure generator can be used for high-pressure liquid working medium from the condenser (2) Pre-cooling the mass R1;

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) after being preheated by the high-pressure solution heat exchanger (13) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially enters the low-pressure absorber (5) through the high-pressure solution heat exchanger (13) and the high-pressure solution throttle valve (12), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttle valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, then passes through the working medium subcooler (15), enters from the bottom of the low-pressure absorber (5), is absorbed by the solution in the low-pressure absorber (5) from bottom to top to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) to enter an intermediate-pressure stage and flows back to the low-pressure absorber (5) from bottom to top; the medium-pressure solution S2 entering the medium-pressure stage enters the low-pressure absorber (5) for heat regeneration and then is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein a part of the solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by the second heat source, and the generated medium-pressure dilute solution S8 passes through the medium-pressure heat exchanger (14) and the medium-pressure solution throttling valve (11) in sequence to be throttled and depressurized to enter the low-pressure absorber (5); the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the solution is boosted by the medium-pressure solution pump (9) and enters the high-pressure stage, the high-pressure concentrated solution S4 flows back from bottom to top to enter the medium-pressure absorber (8), and after the absorption heat is recovered, the solution enters the high-pressure generator (1) through the high-pressure solution heat exchanger (13), and the working medium circulation is finished.

In some of the embodiments, the heating area of the high-pressure generator (1) is expanded from the tower bottom to the stripping section, and the first heat source enters the high-pressure generator (1) from bottom to top to perform dividing wall type heat exchange with the concentrated solution S4 entering the rectifying tower.

In some of these embodiments, the high pressure dilute solution S5 may be returned back into the high pressure generator (1) from bottom to top for heat regeneration.

In some of these embodiments, the intermediate pressure generator (10) may retain the rectification apparatus or may eliminate the rectification apparatus altogether.

In some of these embodiments, the second heat source enters the medium pressure generator (10) from bottom to top, and is recuperatively heat exchanged with the top-down medium pressure solution S7.

In some of these embodiments, the flow regulating valve (7) is able to regulate the proportion of the solution flow entering the medium pressure generator (10).

In some of these embodiments, the low pressure absorber (5) has multiple solution feeds, and the dilute solution from the high pressure generator (1) and the medium pressure generator (10) can be selected at locations and heights depending on the temperature concentration.

In some of these embodiments, the low pressure rich solution S1 may be refluxed back into the low pressure absorber (5) recovering a portion of the heat of absorption.

In some of these embodiments, the medium pressure rich solution S3 may be refluxed into the medium pressure absorber (8) to recover a portion of the absorption heat.

In some embodiments, the valve openings of the medium-pressure solution throttle valve (11), the high-pressure solution throttle valve (12) and the working medium throttle valve (3) are adjustable, so that the pressure of the medium-pressure stage and the low-pressure stage is controlled.

By adopting the technical scheme, the invention has the following technical effects:

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention or in the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a dual-heat-source-driven variable-temperature absorption refrigeration system according to embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a dual-heat-source-driven variable-temperature absorption refrigeration system according to embodiment 2 of the present invention;

fig. 3 is a schematic structural diagram of a dual-heat-source-driven variable-temperature absorption refrigeration system according to embodiment 3 of the present invention;

fig. 4 is a schematic structural diagram of a dual-heat-source-driven variable-temperature absorption refrigeration system according to embodiment 4 of the present invention.

Wherein: 1-a high voltage generator; 2-a condenser; 3-working medium throttle valve; 4-an evaporator; 5-a low pressure absorber; 6-low pressure solution pump; 7-a flow regulating valve; 8-a medium pressure absorber; 9-medium pressure solution pump; 10-a medium voltage generator; 11-medium pressure solution throttle valve; 12-high pressure solution throttle valve; 13-high pressure solution heat exchanger; 14-medium pressure solution heat exchanger; 15-working medium precooler.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "horizontal", "inside", "outside", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

Example 1

Referring to fig. 1, a schematic structural diagram of a dual-heat-source-driven variable-temperature absorption refrigeration system according to an embodiment of the present invention 1 includes: a heat source flow path, a cooling medium flow path and a circulating working medium flow path. The heat source flow path includes a first heat source and a second heat source. The circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises the high-pressure generator (1) and the condenser (2), the medium-pressure stage comprises the medium-pressure generator (10), the medium-pressure absorber (8) and the flow regulating valve (7), the low-pressure stage comprises the evaporator (4) and the low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through the working medium throttle valve (3) and the high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through the medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected through the low-pressure solution pump (6) and the medium-pressure solution throttle valve (11).

The operation of which is described in detail below.

The first heat source enters the high-pressure generator (1) from the heat source inlet H1 to heat the circulating working medium, the temperature is gradually reduced, and then the circulating working medium flows out from the heat source outlet H2; the second heat source enters the medium-pressure generator (10) from the heat source inlet H3 to heat the circulating working medium, the temperature is gradually reduced, and then the circulating working medium flows out from the heat source outlet H4.

It will be appreciated that the medium pressure generator (10) is at a lower pressure and the saturation temperature of the ammonia is lower, so that the second heat source temperature entering the medium pressure generator (10) is generally lower than the first heat source temperature entering the high pressure generator (1).

And a cooling medium W1 in the cooling medium flow path respectively enters the condenser (2), the medium-pressure absorber (8) and the low-pressure absorber (5) to cool a circulating working medium. Preferably, the cooling medium W1 in the cooling medium flow path is cooling water.

It can be understood that the medium-pressure generator (10) is connected with the medium-pressure absorber (8), and the high-pressure stage and the low-pressure stage of the system circulating working medium are communicated, so that the system can still stably operate without a rectifying device, and the equipment cost and the operation difficulty can be reduced by omitting the rectifying device.

It can be understood that the high-pressure generator (1) and the medium-pressure generator (10) both adopt a temperature-changing generation process, namely, a heat medium fluid performs countercurrent wall-type heat exchange with a solution from top to bottom from bottom to top, and the temperature of the heat medium fluid is gradually reduced to match the generation process of the solution.

In some embodiments, the flow regulating valve (7) can regulate the flow proportion of the solution entering the medium-pressure generator (10), so that the matching of a system and a heat source is realized.

The dual-heat-source-driven variable-temperature absorption refrigeration system provided by the embodiment 1 of the invention introduces a generator and an absorber with intermediate pressure on the basis of the traditional single-effect absorption refrigeration system, recovers a medium-low temperature heat source through a medium-pressure generator, improves the concentration of a circulating working medium through the medium-pressure absorber, and greatly improves the residual heat utilization temperature span by combining a variable-temperature fractionation technology; the matching of the system and a heat source can be realized by adjusting the flow ratio of the solution entering the medium-pressure generator and the medium-pressure absorber, and the variable working condition characteristic and the application range of the system are improved; in addition, the gas phase outlet of the medium pressure generator is connected with the medium pressure absorber, so that a rectifying device can be omitted, and the equipment volume and the cost are reduced.

Example 2

Referring to fig. 2, a dual heat source driven variable temperature absorption refrigeration system is provided for embodiment 2, which includes a heat source flow path, a cooling medium flow path and a circulating medium flow path; the heat source flow path includes a first heat source and a second heat source; the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises the high-pressure generator (1), the condenser (2) and the high-pressure solution heat exchanger (13), the medium-pressure stage comprises the medium-pressure generator (10), the medium-pressure absorber (8), the medium-pressure solution heat exchanger (14) and the flow regulating valve (7), the low-pressure stage comprises the evaporator (4) and the low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through the working medium throttle valve (3) and the high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through the medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected through the low-pressure solution pump (6) and the medium-pressure solution throttle valve (11).

The following description is made in detail, and for the sake of brevity, only the differences from example 1 will be described below.

The first heat source enters the high-pressure generator (1) from the heat source inlet H1 to heat the circulating working medium, the temperature of the circulating working medium is gradually reduced, then the circulating working medium flows out of the heat source outlet H2, the second heat source enters the medium-pressure generator (10) from the heat source inlet H3 to heat the circulating working medium, the temperature of the circulating working medium is gradually reduced, and then the circulating working medium flows out of the heat source outlet H4.

And the cooling medium W1 in the cooling medium flow path respectively enters the condenser (2), the medium pressure absorber (8) and the low pressure absorber (5) to cool the circulating working medium.

In the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) after being preheated by the high-pressure solution heat exchanger (13) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially enters the low-pressure absorber (5) through the high-pressure solution heat exchanger (13) and the high-pressure solution throttle valve (12), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttle valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, and then is absorbed by the solution of the low-pressure absorber (5) to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) and enters an intermediate-pressure stage; the medium-pressure solution S2 entering the medium-pressure stage is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein, a part of solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by the second heat source, the generated medium-pressure dilute solution S8 sequentially passes through the medium-pressure solution heat exchanger (14) and the medium-pressure solution throttle valve (11) to be throttled and depressurized and enters the low-pressure absorber (5), the solution entering the medium-pressure absorber (8) absorbs gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the solution is boosted by the medium-pressure solution pump (9) to enter the high-pressure stage, and the working medium circulation is finished.

It can be understood that the high-pressure dilute solution S5 generated by the high-pressure generator (1) has a relatively high temperature, and can perform countercurrent heat exchange with the cycle fluid S4 and preheat the cycle fluid S4, so as to reduce the heat load of the high-pressure generator (1) and improve the heat economy of the system.

It can be understood that the medium-pressure dilute solution S8 generated by the medium-pressure generator (10) and having a temperature higher than that of the medium-pressure solution S7 can perform counter-current heat exchange with the medium-pressure solution S7 and preheat the medium-pressure solution S7, so as to reduce the heat load of the medium-pressure generator (10) and improve the heat economy of the system.

The dual-heat-source-driven variable-temperature absorption refrigeration system provided by the embodiment 2 of the invention introduces a generator and an absorber with intermediate pressure on the basis of the traditional single-effect absorption refrigeration system, recovers a medium-low temperature heat source through a medium-pressure generator, improves the concentration of a circulating working medium through the medium-pressure absorber, and greatly improves the residual heat utilization temperature span by combining a variable-temperature fractionation technology; the matching of the system and a heat source can be realized by adjusting the flow ratio of the solution entering the medium-pressure generator and the medium-pressure absorber, and the variable working condition characteristic and the application range of the system are improved; in addition, the gas phase outlet of the medium-pressure generator is connected with the medium-pressure absorber, so that the rectification device can be omitted, the equipment volume and the cost are reduced, compared with the system provided by the embodiment 1, the solution heat regenerator is introduced, the heat load of the generator is reduced, and the heat economy of the system is improved.

Example 3

Referring to fig. 3, a dual heat source driven variable temperature absorption refrigeration system according to embodiment 3 of the present invention is provided, which includes a heat source flow path, a cooling medium flow path, and a circulating medium flow path; the heat source flow path comprises a first heat source and a second heat source, and the first heat source outlet H2 is connected with the second heat source inlet H3; the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises the high-pressure generator (1), the condenser (2) and the high-pressure solution heat exchanger (13), the medium-pressure stage comprises the medium-pressure generator (10), the medium-pressure absorber (8), the medium-pressure solution heat exchanger (14) and the flow regulating valve (7), the low-pressure stage comprises the evaporator (4) and the low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through the working medium throttle valve (3) and the high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through the medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected through the low-pressure solution pump (6) and the medium-pressure solution throttle valve (11).

The heat source firstly enters the high-pressure generator (1) from the heat source inlet H1 from bottom to top to heat the circulating working medium, the temperature is gradually reduced, then the heat source flows out from the heat source outlet H2, and enters the medium-pressure generator (10) from bottom to top through the heat source inlet H3 to heat the circulating working medium, the temperature is gradually reduced, and then the heat source flows out from the heat source outlet H4.

It will be appreciated that the first heat source outlet H2 of the heat source flow path is connected to the second heat source inlet H3, representing a single heat source entering the high pressure generator (1) and the intermediate pressure generator (10) in sequence.

It will be appreciated that the medium pressure generator (10) is at a lower pressure and the saturation temperature of the ammonia is lower, so that in general the heat source enters the high pressure generator (1) first and then the medium pressure generator (10) to be cascaded.

The dual-heat-source-driven variable-temperature absorption refrigeration system provided by the embodiment 3 of the invention introduces a generator and an absorber with intermediate pressure on the basis of the traditional single-effect absorption refrigeration system, recovers a medium-low temperature heat source through a medium-pressure generator, improves the concentration of a circulating working medium through the medium-pressure absorber, and greatly improves the residual heat utilization temperature span by combining a variable-temperature fractionation technology; the matching of the system and a heat source can be realized by adjusting the flow ratio of the solution entering the medium-pressure generator and the medium-pressure absorber, and the variable working condition characteristic and the application range of the system are improved; in addition, the gas phase outlet of the medium pressure generator is connected with the medium pressure absorber, so that the rectification device can be omitted, the equipment volume and the cost are reduced, and compared with the embodiment 2, a single heat source sequentially enters the high pressure generator and the medium pressure generator of the system, and the high-temperature cascade utilization of the heat source is completed.

Example 4

Referring to fig. 4, a dual heat source driven variable temperature absorption refrigeration system is provided in embodiment 4 of the present application, including a heat source flow path, a cooling medium flow path, and a circulating medium flow path; the heat source flow path includes a first heat source and a second heat source; the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1), a condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected through a working medium throttle valve (3) and a high-pressure solution throttle valve (12), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), the medium-pressure stage and the low-pressure stage are connected through a low-pressure solution pump (6) and a medium-pressure solution throttle valve (11), a working medium subcooler (15) is further arranged between the high-pressure stage and the medium-pressure stage, and low-temperature working medium R3 from the medium-pressure generator can be used for high-pressure liquid working medium R1 from the condenser (2) And (4) precooling.

It can be understood that a working medium subcooler (15) is arranged between the high-pressure stage and the medium-pressure stage, and the low-temperature working medium R3 from the medium-pressure generator can precool the high-pressure liquid working medium R1 from the condenser (2), so that the heat economy of the system can be improved.

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) after being preheated by the high-pressure solution heat exchanger (13) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially enters the low-pressure absorber (5) through the high-pressure solution heat exchanger (13) and the high-pressure solution throttle valve (12), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttle valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, then passes through the working medium subcooler (15), enters from the bottom of the low-pressure absorber (5), is absorbed by the solution in the low-pressure absorber (5) from bottom to top to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) to enter an intermediate-pressure stage and flows back to the low-pressure absorber (5); the medium-pressure solution S2 entering the medium-pressure stage enters the low-pressure absorber (5) for heat regeneration and then is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein a part of the solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by the second heat source, and the generated medium-pressure dilute solution S8 passes through the medium-pressure heat exchanger (14) and the medium-pressure solution throttling valve (11) in sequence to be throttled and depressurized to enter the low-pressure absorber (5); the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the medium-pressure concentrated solution is boosted by the medium-pressure solution pump (9) and enters the high-pressure stage, the high-pressure concentrated solution S4 flows back to the medium-pressure absorber (8), and after the absorption heat is recovered, the high-pressure concentrated solution enters the high-pressure generator (1) through the high-pressure solution heat exchanger (13), and the working medium circulation is ended.

It can be understood that because the outlet temperature of the solution at the bottom of the low-pressure absorber (5) is lower, the temperature at the top is higher, and the absorption heat is released in the absorption process, the low-pressure solution S2 flows back into the low-pressure absorber (5) from bottom to top and performs recuperation heat exchange with the solution, and part of the absorption heat is recovered, so that the heat economy of the system can be improved.

It can be understood that the outlet temperature of the solution at the bottom of the medium pressure absorber (8) is lower, the temperature at the top is higher, the high pressure concentrated solution S4 flows back into the medium pressure absorber (8) from bottom to top and performs recuperative heat exchange with the solution, and part of the absorbed heat is recovered, thereby improving the heat economy of the system.

The dual-heat-source-driven variable-temperature absorption refrigeration system provided by the embodiment 4 of the invention introduces a generator and an absorber with intermediate pressure on the basis of the traditional single-effect absorption refrigeration system, recovers a medium-low temperature heat source through a medium-pressure generator, improves the concentration of a circulating working medium through the medium-pressure absorber, and greatly improves the residual heat utilization temperature span by combining a variable-temperature fractionation technology; the matching of the system and a heat source can be realized by adjusting the flow ratio of the solution entering the medium-pressure generator and the medium-pressure absorber, and the variable working condition characteristic and the application range of the system are improved; in addition, the gas phase outlet of the medium pressure generator is connected with the medium pressure absorber, so that the rectification device can be omitted, the equipment volume and the cost are reduced, compared with the embodiment 2, the regeneration of the refrigerating medium is realized through the subcooler, the solution enters the absorber through the backflow of the solution to recover the heat of absorption to realize the regeneration of the solution, and the heat economy of the system is improved.

To better explain the above technical solution, the following simulation calculation was performed on the absorption refrigeration system of example 2 of the present invention with reference to fig. 2, using ammonia-water as a working medium pair.

Assuming that the first heat source inlet temperature is 175 ℃, the second heat source inlet temperature is 90 ℃ and the system heat exchanger pinch point temperature difference is 5 ℃. The first heat source enters the high-pressure generator (1) from bottom to top and carries out countercurrent heat exchange with 77 ℃ ammonia water solution entering the high-pressure generator (1). The ammonia water solution entering the high-pressure generator (1) is heated and analyzed, and the generated ammonia steam enters a condenser to be cooled by cooling water after being rectified by a rectifier, so that the ammonia steam is changed into liquid refrigerating medium liquid ammonia at the temperature of 39 ℃. And then, the liquid ammonia working medium is throttled and depressurized to 0.236MPa through the working medium throttle valve (3), and enters the evaporator (4) to complete the evaporation refrigeration process at the temperature of-15 ℃. The ammonia vapor from the evaporator then enters the low-pressure absorber (5) to be absorbed by the dilute solution from the high-pressure generator (1) and the medium-pressure generator (10) and cooled to 38 ℃ by the cooling water to become a low-pressure concentrated solution S1. The low-pressure concentrated solution is pumped to the intermediate pressure of 0.7MPa by the low-pressure solution pump (6) and enters the intermediate-pressure stage. The solution entering the medium-pressure stage is divided into two streams, of which 80% enters the high-pressure generator (10) via the medium-pressure heat exchanger (14) and 20% enters the medium-pressure absorber (8). The solution entering the medium-pressure generator (10) is heated to 85 ℃, and the liquid-phase dilute solution thereof is cooled to 43 ℃ through the medium-pressure solution heat exchanger (14) and then enters the low-pressure absorber (5). Gas-phase ammonia water steam in the medium-pressure generator (10) enters the medium-pressure absorber (8) to be absorbed by the solution, is cooled to 38 ℃ by cooling water to become low-temperature medium-pressure concentrated solution, then passes through a medium-pressure solution pump to be pumped to 1.5MPa, enters a high-pressure stage, is preheated to 77 ℃ by a high-pressure solution heat exchanger at 170 ℃, enters the high-pressure generator (1), and completes the whole cycle.

Simulation calculations were performed on the absorption refrigeration system of example 3 of the present invention using ammonia-water as a working medium pair in conjunction with fig. 3.

Assuming that the inlet temperature of a first heat source is 175 ℃ and the temperature difference of a narrow point of a system heat exchanger is 5 ℃, the first heat source sequentially enters the high-pressure generator (1) and the medium-pressure generator (10) and is utilized in a cascade mode. The first heat source enters the high-pressure generator (1) from bottom to top to perform countercurrent heat exchange with a 107 ℃ ammonia water solution entering the high-pressure generator (1), the temperature is gradually reduced to 112 ℃, and then the first heat source enters the medium-pressure generator (10) to perform heat exchange with the solution in the medium-pressure generator, and finally the temperature is reduced to 85 ℃. The ammonia water solution entering the high-pressure generator (1) is heated and analyzed, and the generated ammonia steam enters a condenser to be cooled by cooling water after being rectified by a rectifier, so that the ammonia steam is changed into liquid refrigerating medium liquid ammonia at the temperature of 39 ℃. And then, the liquid ammonia working medium is throttled and depressurized to 0.203MPa through the working medium throttle valve (3), and enters the evaporator (4) to complete the evaporation refrigeration process at the temperature of 18 ℃ below zero. The ammonia vapor from the evaporator then enters the low-pressure absorber (5) to be absorbed by the dilute solution from the high-pressure generator (1) and the medium-pressure generator (10) and cooled to 38 ℃ by the cooling water to become a low-pressure concentrated solution S1. The low-pressure concentrated solution is pumped to the intermediate pressure of 0.7MPa by the low-pressure solution pump (6) and enters the intermediate-pressure stage. The solution entering the medium-pressure stage is divided into two streams, wherein 50% of the solution enters the medium-pressure generator (10) through the medium-pressure heat exchanger (14); the other 50% of the solution enters the medium-pressure absorber (8). The solution entering the medium-pressure generator (10) is heated to 107 ℃, and the liquid-phase dilute solution thereof is cooled to 43 ℃ through the medium-pressure solution heat exchanger (14) and then enters the low-pressure absorber (5). Gas-phase ammonia water steam in the medium-pressure generator (10) enters the medium-pressure absorber (8) to be absorbed by the solution, is cooled to 38 ℃ by cooling water to become low-temperature medium-pressure concentrated solution, then passes through a medium-pressure solution pump to be pumped to 1.5MPa, enters a high-pressure stage, is preheated to 107 ℃ by a high-pressure solution heat exchanger, enters the high-pressure generator (1), and completes the whole cycle.

Obviously, the absorption refrigeration system provided by the above embodiment of the present invention is suitable for dual heat source driving, and can recycle waste heat source below 100 ℃; the waste heat temperature of the system reaches more than 90 ℃, which is far higher than that of the traditional system; the flow ratio of the medium pressure solution and the medium pressure solution is adjustable, and the matching of a system and a heat source can be realized; and the gas-phase working medium of the medium-pressure generator enters the medium-pressure absorber, a rectifier is not needed, and the volume and the manufacturing cost of equipment can be reduced.

The foregoing is considered as illustrative only of the preferred embodiments of the invention, and is presented merely for purposes of illustration and description of the principles of the invention and is not intended to limit the scope of the invention in any way. Any modifications, equivalents and improvements made within the spirit and principles of the invention and other embodiments of the invention without the creative effort of those skilled in the art are included in the protection scope of the invention based on the explanation here.

Claims

1. A dual heat source driven variable temperature absorption refrigeration system comprising: a heat source flow path, a cooling medium flow path and a circulating working medium flow path,

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1) and a condenser (2), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected with a high-pressure solution throttling valve (12) through a working medium throttling valve (3), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected with a medium-pressure solution throttling valve (11) through a low-pressure solution pump (6); wherein:

2. A temperature-variable absorption refrigeration system driven by double heat sources is characterized by comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1), a condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected with a high-pressure solution throttle valve (12) through a working medium throttle valve (3), the high-pressure stage and the medium-pressure stage are connected with each other through a medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected with a medium-pressure solution throttle valve (11) through a low-pressure solution pump (6); wherein:

3. A temperature-variable absorption refrigeration system driven by double heat sources is characterized by comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1), a condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected with a high-pressure solution throttle valve (12) through a working medium throttle valve (3), the high-pressure stage and the medium-pressure stage are connected with each other through a medium-pressure solution pump (9), and the medium-pressure stage and the low-pressure stage are connected with a medium-pressure solution throttle valve (11) through a low-pressure solution pump (6);

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) after being preheated by the high-pressure solution heat exchanger (13) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially enters the low-pressure absorber (5) through the high-pressure solution heat exchanger (13) and the high-pressure solution throttle valve (12), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttle valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, and then is absorbed by the solution of the low-pressure absorber (5) to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) and enters an intermediate-pressure stage; the medium-pressure solution S2 entering the medium-pressure stage is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein a part of the solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by a heat source, and the generated medium-pressure dilute solution S8 is throttled and depressurized into the low-pressure absorber (5) through the medium-pressure solution heat exchanger (14) and the medium-pressure solution throttling valve (11) in sequence; the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the pressure is increased by the medium-pressure solution pump (9) to enter the high-pressure stage, and the working medium circulation is finished.

4. A temperature-variable absorption refrigeration system driven by double heat sources is characterized by comprising a heat source flow path, a cooling medium flow path and a circulating working medium flow path;

the circulating working medium flow path is divided into a high-pressure stage, a medium-pressure stage and a low-pressure stage, the high-pressure stage comprises a high-pressure generator (1), a condenser (2) and a high-pressure solution heat exchanger (13), the medium-pressure stage comprises a medium-pressure generator (10), a medium-pressure absorber (8), a medium-pressure solution heat exchanger (14) and a flow regulating valve (7), the low-pressure stage comprises an evaporator (4) and a low-pressure absorber (5), the high-pressure stage and the low-pressure stage are connected with a high-pressure solution throttle valve (12) through a working medium throttle valve (3), the high-pressure stage and the medium-pressure stage are connected through a medium-pressure solution pump (9), the medium-pressure stage and the low-pressure stage are connected through a low-pressure solution pump (6) and a medium-pressure solution throttle valve (11), a working medium subcooler (15) is also arranged between the high-pressure stage and the medium-pressure stage, and low-temperature working medium R3 from the medium-pressure generator can be used for precooling high-pressure liquid working medium R1 from the condenser (2);

in the circulating working medium flow path, a circulating working medium S4 enters the high-pressure generator (1) after being preheated by the high-pressure solution heat exchanger (13) to be heated and analyzed, a high-pressure dilute solution S5 generated by the circulating working medium flow path sequentially enters the low-pressure absorber (5) through the high-pressure solution heat exchanger (13) and the high-pressure solution throttle valve (12), high-pressure steam generated by the high-pressure generator (1) enters the condenser (2) to be condensed into a high-pressure liquid working medium R1, and then is throttled and depressurized by the working medium throttle valve (3) to be changed into a low-pressure two-phase working medium R2 to enter a low-pressure stage; the low-pressure two-phase working medium R2 enters the evaporator (4) to be evaporated and absorb heat to finish the refrigeration process, then passes through the working medium subcooler (15), enters from the bottom of the low-pressure absorber (5), is absorbed by the solution in the low-pressure absorber (5) from bottom to top to obtain a low-pressure concentrated solution S1, and the low-pressure concentrated solution S1 is boosted by the low-pressure solution pump (6) to enter an intermediate-pressure stage and flows back to the low-pressure absorber (5) from bottom to top; the medium-pressure solution S2 entering the medium-pressure stage enters the low-pressure absorber (5) for heat regeneration and then is divided into two parts which respectively enter the medium-pressure generator (10) and the medium-pressure absorber (8); wherein a part of the solution S7 is preheated by the medium-pressure solution heat exchanger (14) firstly, then enters the medium-pressure generator (10) to be heated by the second heat source, and the generated medium-pressure dilute solution S8 passes through the medium-pressure solution heat exchanger (14) and the medium-pressure solution throttling valve (11) in sequence to be throttled and depressurized to enter the low-pressure absorber (5); the solution entering the medium-pressure absorber (8) absorbs the gas-phase working medium from the medium-pressure generator (10), the solution concentration is further increased to become medium-pressure concentrated solution S3, the medium-pressure concentrated solution is boosted by the medium-pressure solution pump (9) and enters the high-pressure stage, the high-pressure concentrated solution S5 flows back to the medium-pressure absorber (8), and after the absorption heat is recovered, the high-pressure concentrated solution enters the high-pressure generator (1) through the high-pressure solution heat exchanger (13), and the working medium circulation is ended.

5. The dual heat source driven variable temperature absorption refrigeration system according to claim 1 or 2 or 3 or 4, wherein the heating zone of the high pressure generator (1) is extended from the bottom of the column to the stripping section, and the first heat source enters the high pressure generator (1) from bottom to top to perform recuperative heat exchange with the concentrated solution entering the rectification column.

6. A dual heat source driven variable temperature absorption refrigeration system as set forth in claim 1 or 2 or 3 or 4 wherein said high pressure dilute solution S5 is returned from bottom to top into said high pressure generator (1) for recuperation.

7. Double heat source driven absorption refrigeration system of the variable temperature type according to claim 1 or 2 or 3 or 4, characterized in that the medium pressure generator (10) can either retain or completely eliminate the rectifying means.

8. A dual heat source driven variable temperature absorption refrigeration system as set forth in claim 1 or 2 or 3 or 4 wherein said second heat source enters said intermediate pressure generator (10) from bottom to top for recuperative heat exchange with top-down intermediate pressure solution S2.

9. A dual heat source driven absorption refrigeration system of the variable temperature type according to claim 1 or 2 or 3 or 4 wherein the flow regulating valve (7) is capable of regulating the ratio of the solution flow into the medium pressure generator (10).

10. A dual heat source driven variable temperature absorption refrigeration system as set forth in claim 1 or 2 or 3 or 4 wherein said low pressure absorber (5) has a plurality of solution feed ports, the dilute solution from said high pressure generator (1) and medium pressure generator (10) being selected in position and height in accordance with temperature concentration.

11. A dual heat source driven variable temperature absorption refrigeration system as set forth in claim 1 or 2 or 3 or 4 wherein said rich low pressure solution S1 can be refluxed into said low pressure absorber (5) to recover a portion of the heat of absorption.

12. A dual heat source driven variable temperature absorption refrigeration system as set forth in claim 1 or 2 or 3 or 4 wherein said concentrated medium pressure solution S3 is refluxed into said medium pressure absorber (8) to recover a portion of the heat of absorption.

13. The dual heat source driven variable temperature absorption refrigeration system according to claim 1 or 2 or 3 or 4 wherein the valve openings of the medium pressure solution throttle valve (11), the high pressure solution throttle valve (12) and the working medium throttle valve (3) are adjustable to control the pressures of the medium pressure stage and the low pressure stage.