Two-stage first type lithium bromide absorption heat pump unit with evaporation and absorption sections

Abstract

The application discloses a two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption in sections, which comprises a condenser, a two-stage generator, a high-pressure section evaporator, a high-pressure section two-stage absorber, a low-pressure section two-stage absorber, a low-pressure section evaporator, a one-stage generator, a one-stage absorber, a one-stage heat exchanger, a two-stage heat exchanger and pipelines arranged between the components. The unit mainly divides a low-temperature waste heat source into two sections, increases the concentration difference of the one-stage solution circulation, increases the heat exchange temperature difference, reduces the heat exchange area, improves the performance coefficient, and the circulating water of the high-pressure section evaporator flows into the low-pressure section evaporator by pressure difference and height difference, so that a low-pressure section circulating pump is not needed, power saving is realized, the overall investment and operation cost are reduced, the unit has an attractive appearance and compact structure, multiple waste heat is recovered, and the comprehensive energy utilization rate is improved.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and more specifically, to a two-stage, first-type lithium bromide absorption heat pump unit with evaporation and absorption stages. Background Technology

[0002] In existing technologies, medium-temperature hot water is needed in production processes or daily life, but obtaining this water requires energy. Simultaneously, a large amount of medium (low) temperature waste heat is generated during production processes, some of which is discharged unusable, resulting in waste. To save energy and reduce emissions, lithium bromide heat pump heating technology, driven by a high-temperature heat source, recovers and utilizes this low-temperature waste heat to produce medium-temperature hot water, saving 40% of energy consumption and achieving comprehensive energy utilization.

[0003] In applications of lithium bromide heat pump heating technology, different types of heat pump units are selected based on the quality of the driving heat source, low-temperature waste heat, and required medium-temperature hot water parameters. Commonly used lithium bromide heat pumps include single-effect, double-effect, and two-stage type I lithium bromide absorption heat pump units. When the provided external parameters cannot be met by single-effect and double-effect lithium bromide heat pumps, a two-stage type I lithium bromide absorption heat pump with a lower coefficient of performance is considered. The structure of traditional two-stage type I lithium bromide absorption heat pump units is as follows: Figure 1 As shown, its coefficient of performance is around 1.4, including condenser 1, secondary generator 2, secondary absorber 3, evaporator 4, primary generator 5, primary absorber 6, secondary dilute solution pump 7, refrigerant pump 8, primary concentrated solution pump 9, primary dilute solution pump 10, primary heat exchanger 11, and secondary heat exchanger 12.

[0004] However, in practical applications, when the driving heat source has a low grade, the low temperature waste heat source outlet temperature is low, and the medium temperature hot water outlet temperature requirement is high, ordinary two-stage type I lithium bromide absorption heat pump units are difficult to meet the requirements or have high equipment investment costs due to the limitations of poor parameter conditions.

[0005] In summary, how to ensure that heat pump units can meet parameter requirements under poor external operating conditions, while also reducing the equipment's own investment costs, improving the coefficient of performance, recovering more waste heat, and saving energy, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption stages, which can ensure that the heat pump unit can meet the usage requirements and save more energy and costs.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A two-stage lithium bromide absorption heat pump unit with evaporation and absorption sections includes: a condenser, a secondary generator, an evaporator, a secondary absorber, a primary generator, a primary absorber, a primary heat exchanger, a secondary heat exchanger, and piping between the components. The evaporator has a two-stage structure, including a high-pressure evaporator and a low-pressure evaporator. The secondary absorber also has a two-stage structure, including a high-pressure secondary absorber and a low-pressure secondary absorber.

[0009] The high-pressure section evaporator and the high-pressure section secondary absorber are in one cavity, and the low-pressure section evaporator and the low-pressure section secondary absorber are in another cavity. The high-pressure section evaporator, the high-pressure section secondary absorber, the condenser, and the secondary generator are in a first cylinder, and the middle of the first cylinder is divided into two cavities by a vertical partition, located at the upper part of the unit. The low-pressure section evaporator, the low-pressure section secondary absorber, the primary generator, and the primary absorber are in a second cylinder, and the middle of the second cylinder is divided into two cavities by a vertical partition, located at the lower part of the unit.

[0010] Preferably, an intermediate solution pump is provided at the bottom of the liquid bladder of the low-pressure section secondary absorber, and an intermediate solution pipeline is provided between the outlet of the intermediate solution pump and the spray pipe of the low-pressure section secondary absorber.

[0011] Preferably, a high-pressure section secondary dilute solution pump is provided at the bottom of the liquid bladder of the high-pressure section secondary absorber, and a secondary dilute solution pipeline is provided between the outlet of the high-pressure section secondary dilute solution pump and the primary heat exchanger.

[0012] Preferably, a low-pressure section refrigerant pump is provided at the bottom of the liquid bladder of the low-pressure section evaporator, and a refrigerant water inlet pipe for the high-pressure section evaporator is provided between the outlet of the low-pressure section refrigerant pump and the spray pipe of the high-pressure section evaporator.

[0013] Preferably, a low-temperature refrigerant water throttling pipe is provided between the bottom of the liquid bladder of the high-pressure section evaporator and the spray pipe of the low-pressure section evaporator, and a high-temperature refrigerant water throttling pipe led out from the bottom of the liquid bladder of the condenser is connected to the flash tube of the low-pressure section evaporator.

[0014] Preferably, the driving heat source is connected in series and enters the heat transfer tubes of the secondary generator and the primary generator in sequence;

[0015] Alternatively, the driving heat source may be connected in parallel into the heat transfer tubes of the secondary generator and the heat transfer tubes of the primary generator.

[0016] Preferably, the low-temperature waste heat source is connected in series and enters the heat transfer tubes of the high-pressure section evaporator and the low-pressure section evaporator in sequence.

[0017] Preferably, the medium-temperature hot water first enters in parallel into the heat transfer tubes of the high-pressure section secondary absorber and the low-pressure section secondary absorber, and then enters in series into the heat transfer tubes of the primary absorber and the condenser.

[0018] When using the two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption sections provided by this invention, the solution circulation process of the unit consists of two solution circulations with different concentrations. One high-concentration solution circulation consists of a primary generator, a low-pressure secondary absorber, a high-pressure secondary absorber, and a primary heat exchanger. The other low-concentration solution circulation consists of a secondary generator, a primary absorber, and a secondary heat exchanger.

[0019] The refrigerant cycle of this unit is as follows: High-temperature refrigerant vapor generated by the secondary generator enters the condenser and is condensed into high-temperature refrigerant water. This high-temperature refrigerant water then enters the low-pressure evaporator via a high-temperature refrigerant water throttling pipe for flashing. The unflashed refrigerant water enters the liquid sac of the low-pressure evaporator and is pumped by the low-pressure refrigerant pump into the high-pressure evaporator for evaporation into refrigerant vapor I. The unevaporated refrigerant water enters the liquid sac of the high-pressure evaporator and, driven by pressure and elevation differences, enters the low-pressure evaporator via a low-temperature refrigerant water throttling pipe for evaporation into refrigerant vapor II. Refrigerant vapor II is absorbed by the high-concentration concentrated solution from the primary generator to become an intermediate solution. Refrigerant vapor I is absorbed by the intermediate solution from the low-pressure secondary absorber to become a dilute solution. This dilute solution enters the primary generator for concentration, generating low-temperature refrigerant vapor which enters the primary absorber. The low-temperature refrigerant vapor is absorbed by the higher-concentration concentrated solution from the secondary generator to become a low-concentration dilute solution. This low-concentration dilute solution is pumped by the primary dilute solution pump into the secondary generator for concentration, generating high-temperature refrigerant vapor. This cycle continues continuously.

[0020] By employing the aforementioned novel process and structural arrangement, the low-temperature waste heat source is divided into two cooling stages. This increases the concentration difference in one of the high-concentration solution circulation stages. Specifically, the concentrated solution from the primary generator first absorbs refrigerant vapor in the low-pressure secondary absorber to become an intermediate solution, before entering the high-pressure secondary absorber to continue absorbing refrigerant vapor, resulting in an even lower concentration solution. This increased concentration difference in the solution circulation leads to a higher heat exchange temperature difference, a smaller heat exchange area, and a lower solution circulation volume. This reduces the heat load on the heat exchanger, lowers the material costs of the unit, and reduces equipment investment costs. Furthermore, the unit has an aesthetically pleasing and compact design, improved performance coefficients, and can recover more waste heat, increasing overall energy utilization. Simultaneously, the refrigerant water in the high-pressure evaporator reliably flows automatically into the low-pressure evaporator based on pressure and height differences, eliminating the need for an additional low-pressure refrigerant circulation pump, thus saving energy and reducing investment and operating costs.

[0021] In summary, the two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption stages provided by this invention can ensure that the heat pump unit can meet the parameter requirements even under poor external operating conditions, while also reducing the equipment's own investment cost, improving the coefficient of performance, recovering more waste heat, and saving energy. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a previous two-stage type I lithium bromide absorption heat pump unit.

[0024] Figure 2 This is a schematic diagram of the structure of the two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption sections provided by the present invention.

[0025] Figures 1-2 middle:

[0026] 1 is the condenser, 2 is the secondary generator, 3 is the secondary absorber, 4 is the evaporator, 5 is the primary generator, 6 is the primary absorber, 7 is the secondary dilute solution pump, 8 is the refrigerant pump, 9 is the primary concentrated solution pump, 10 is the primary dilute solution pump, 11 is the primary heat exchanger, 12 is the secondary heat exchanger, 13 is the high-pressure section evaporator, 14 is the high-pressure section secondary absorber, 15 is the high-pressure section secondary dilute solution pump, and 16 is the low-temperature refrigerant water throttling pipeline. 17 is the intermediate solution pipeline, 18 is the low-pressure section secondary absorber, 19 is the low-pressure section evaporator, 20 is the intermediate solution pump, 21 is the low-pressure section refrigerant pump, 22 is the secondary dilute solution pipeline, 23 is the refrigerant water inlet pipeline to the high-pressure section evaporator, 24 is the high-temperature refrigerant water throttling pipeline, 25 is the driving heat source inlet, 26 is the low-temperature waste heat source inlet, 27 is the medium-temperature hot water inlet, 28 is the driving heat source outlet, 29 is the low-temperature waste heat source outlet, and 30 is the medium-temperature hot water outlet. Detailed Implementation

[0027] The core of this invention is to provide a two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption sections, which can improve the coefficient of performance of the equipment and save more energy and costs even under poor external operating conditions.

[0028] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of the two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption sections provided by the present invention.

[0029] This specific embodiment provides a two-stage lithium bromide absorption heat pump unit with evaporation and absorption sections, including: a condenser 1, a secondary generator 2, an evaporator 4, a secondary absorber 3, a primary generator 5, a primary absorber 6, a primary heat exchanger 11, a secondary heat exchanger 12, and pipelines between the components. The evaporator 4 has a two-stage structure, including a high-pressure evaporator 13 and a low-pressure evaporator 19. The secondary absorber 3 has a two-stage structure, including a high-pressure secondary absorber 14 and a low-pressure secondary absorber 18.

[0030] The high-pressure section evaporator 13 and the high-pressure section secondary absorber 14 are in one chamber, and the low-pressure section evaporator 19 and the low-pressure section secondary absorber 18 are in another chamber. The high-pressure section evaporator 13, the high-pressure section secondary absorber 14, the condenser 1, and the secondary generator 2 are in the first cylinder, which is divided into two chambers by a vertical partition in the middle of the first cylinder and is located at the top of the unit. The low-pressure section evaporator 19, the low-pressure section secondary absorber 18, the primary generator 5, and the primary absorber 6 are in the second cylinder, which is divided into two chambers by a vertical partition in the middle of the second cylinder and is located at the bottom of the unit.

[0031] Preferably, an intermediate solution pump 20 is provided at the bottom of the liquid bladder of the low-pressure section secondary absorber 18, and an intermediate solution pipeline 17 is provided between the outlet of the intermediate solution pump 20 and the spray pipe of the low-pressure section secondary absorber 18.

[0032] Preferably, a high-pressure section secondary dilute solution pump 15 is provided at the bottom of the liquid bladder of the high-pressure section secondary absorber 14, and a secondary dilute solution pipeline 22 is provided between the outlet of the high-pressure section secondary dilute solution pump 15 and the primary heat exchanger 11.

[0033] Preferably, a low-pressure section refrigerant pump 21 is provided at the bottom of the liquid bladder of the low-pressure section evaporator 19, and a refrigerant water inlet pipe 23 is provided between the outlet of the low-pressure section refrigerant pump 21 and the spray pipe of the high-pressure section evaporator 13.

[0034] Preferably, a low-temperature refrigerant water throttling pipe 16 is provided between the bottom of the liquid bladder of the high-pressure section evaporator 13 and the spray pipe of the low-pressure section evaporator 19, and a high-temperature refrigerant water throttling pipe 24 led out from the bottom of the liquid bladder of the condenser 1 is connected to the flash tube of the low-pressure section evaporator 19.

[0035] The high-concentration solution circulation of this unit consists of a primary generator 5, a low-pressure secondary absorber 18, a high-pressure secondary absorber 14, and a primary heat exchanger 11. In this high-concentration solution circulation, the concentrated solution from the primary generator 5 is lifted by the primary concentrated solution pump 9, cooled by the primary heat exchanger 11, and enters the low-pressure secondary absorber 18 to absorb the refrigerant vapor evaporated by the low-pressure evaporator 19, becoming a lower-concentration intermediate solution. The intermediate solution is pumped by the intermediate solution pump 20 into the high-pressure secondary absorber 14 to continue absorbing the refrigerant vapor evaporated by the high-pressure evaporator 13, becoming a dilute solution. The dilute solution is lifted by the high-pressure secondary dilute solution pump 15, heated by the primary heat exchanger 11, and enters the primary generator 5 to be concentrated into a high-concentration concentrated solution.

[0036] Another low-concentration solution cycle consists of a secondary generator 2, a primary absorber 6, and a secondary heat exchanger 12. In this solution cycle, the concentrated solution from the secondary generator 2 is cooled by the pressure and height difference through the secondary heat exchanger 12 and flows into the primary absorber 6 to absorb the refrigerant vapor generated by the primary generator 5, thus becoming a low-concentration dilute solution. The low-concentration dilute solution is then pumped by the primary dilute solution pump 10, heated by the secondary heat exchanger 12, and enters the secondary generator 2 to be concentrated into a higher-concentration solution.

[0037] The refrigerant circulation process of this unit is as follows: the high-temperature refrigerant vapor generated by the secondary generator 2 enters the condenser 1 and is condensed into high-temperature refrigerant water. The high-temperature refrigerant water enters the low-pressure section evaporator 19 through the high-temperature refrigerant water throttling pipe 24 and flashes. The refrigerant water that does not flash enters the liquid bladder of the low-pressure section evaporator 19 and is pumped into the high-pressure section evaporator 13 by the low-pressure section refrigerant pump 21 and evaporates into refrigerant vapor I. The unevaporated refrigerant water enters the liquid bladder of the high-pressure section evaporator 13 and, driven by the pressure difference and height difference, enters the low-temperature refrigerant water throttling pipe 16 and evaporates into refrigerant vapor II in the low-pressure section evaporator 19.

[0038] Refrigerant vapor II is absorbed by the high-concentration concentrated solution from the first-stage generator 5 to become an intermediate solution. Refrigerant vapor I is absorbed by the intermediate solution from the low-pressure section secondary absorber 18 to become a dilute solution. This dilute solution is then concentrated in the first-stage generator 5 to produce low-temperature refrigerant vapor, which enters the first-stage absorber 6. The low-temperature refrigerant vapor is absorbed by the higher-concentration concentrated solution from the secondary generator 2 to become a low-concentration dilute solution. This low-concentration dilute solution is pumped into the secondary generator 2 by the first-stage dilute solution pump 10 to produce high-temperature refrigerant vapor, and this cycle continues.

[0039] Based on the above embodiments, preferably, the driving heat source 25 is connected in series and enters the heat transfer tube of the secondary generator 2 and the heat transfer tube of the primary generator 5 in sequence; or the driving heat source 25 is connected in parallel and enters the heat transfer tube of the secondary generator 2 and the heat transfer tube of the primary generator 5.

[0040] That is, the driving heat source in the external system can be connected in series and enter the heat transfer tubes of the secondary generator 2 and the primary generator 5 in sequence, or the driving heat source in the external system can be connected in parallel and enter the heat transfer tubes of the secondary generator 2 and the primary generator 5 to heat the solution outside the tubes, concentrate it and generate refrigerant vapor. After the driving heat source releases heat, it flows out of the unit from the driving heat source outlet 28.

[0041] Preferably, the low-temperature waste heat source inlet 26 is connected in series and enters the heat transfer tubes of the high-pressure section evaporator 13 and the low-pressure section evaporator 19 in sequence. That is, the low-temperature waste heat source inlet 26 first enters the heat transfer tubes of the high-pressure section evaporator 13, and then enters the heat transfer tubes of the low-pressure section evaporator 19 to heat the refrigerant water outside the tubes to make it evaporate. After releasing heat, the low-temperature waste heat source flows out of the unit from the low-temperature waste heat source outlet 29.

[0042] Preferably, the medium-temperature hot water inlet 27 first enters in parallel into the heat transfer tubes of the high-pressure section secondary absorber 14 and the low-pressure section secondary absorber 18, and then enters in series into the heat transfer tubes of the primary absorber 6 and the condenser 1. That is, the medium-temperature hot water to be produced enters 27 first in parallel into the heat transfer tubes of the high-pressure section secondary absorber 14 and the low-pressure section secondary absorber 18, and then merges together before entering in series into the heat transfer tubes of the primary absorber 6 and the condenser 1. Due to the heat of absorption and condensation of the solution outside the absorber tubes, the medium-temperature hot water's temperature increases, and it flows out of the unit from the medium-temperature hot water outlet 30.

[0043] The driving heat source and the low-temperature waste heat source can be water, heat transfer oil, steam or other heat sources.

[0044] Through the aforementioned novel process and structural arrangement, the low-temperature waste heat source 26 is divided into two cooling stages, increasing the concentration difference of one of the high-concentration solution circulation stages. Specifically, the concentrated solution from the primary generator 5 first absorbs refrigerant vapor in the low-pressure secondary absorber 18 to become an intermediate solution, and then enters the high-pressure secondary absorber 14 to continue absorbing refrigerant vapor, becoming an even lower-concentration dilute solution. This increased concentration difference in the solution circulation leads to a higher heat exchange temperature difference, a smaller heat exchange area, and a lower solution circulation volume, resulting in a reduced heat load on the heat exchanger, lower material costs for unit manufacturing, and lower equipment investment costs. Furthermore, the unit has an aesthetically pleasing and compact structure, improved performance coefficients, and can recover more waste heat, improving overall energy utilization. Simultaneously, the refrigerant water in the high-pressure evaporator 13 reliably flows automatically into the low-pressure evaporator 19 based on pressure and height differences, eliminating the need for an additional low-pressure refrigerant circulation pump, thus saving energy and reducing investment and operating costs.

[0045] In summary, the two-stage first-type lithium bromide absorption heat pump unit with evaporation and absorption stages provided by this invention can ensure that the heat pump unit can meet the parameter requirements even under poor external operating conditions, while also reducing the equipment's own investment cost, improving the coefficient of performance, recovering more waste heat, and saving energy.

Claims

1. A two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption stages, comprising: The condenser (1), secondary generator (2), evaporator (4), secondary absorber (3), primary generator (5), primary absorber (6), primary heat exchanger (11), secondary heat exchanger (12), and pipelines between the components are characterized in that the evaporator (4) has a two-stage structure, which includes a high-pressure section evaporator (13) and a low-pressure section evaporator (19), and the secondary absorber (3) has a two-stage structure, which includes a high-pressure section secondary absorber (14) and a low-pressure section secondary absorber (18). The high-pressure section evaporator (13) and the high-pressure section secondary absorber (14) are in one cavity, and the low-pressure section evaporator (19) and the low-pressure section secondary absorber (18) are in another cavity. The high-pressure section evaporator (13), the high-pressure section secondary absorber (14), the condenser (1), and the secondary generator (2) are in a first cylinder, and the middle part of the first cylinder is divided into two cavities by a vertical partition, located at the upper part of the unit. The low-pressure section evaporator (19), the low-pressure section secondary absorber (18), the primary generator (5), and the primary absorber (6) are in a second cylinder, and the middle part of the second cylinder is divided into two cavities by a vertical partition, located at the lower part of the unit. An intermediate solution pump (20) is provided at the bottom of the liquid bladder of the low-pressure section secondary absorber (18), and an intermediate solution pipeline (17) is provided between the outlet of the intermediate solution pump (20) and the spray pipe of the low-pressure section secondary absorber (18); a high-pressure section secondary dilute solution pump (15) is provided at the bottom of the liquid bladder of the high-pressure section secondary absorber (14), and a secondary dilute solution pipeline (22) is provided between the outlet of the high-pressure section secondary dilute solution pump (15) and the primary heat exchanger (11); in the low-pressure section evaporator (19) A low-pressure section refrigerant pump (21) is provided at the bottom of the liquid bladder of the condenser (1). A refrigerant water inlet pipe (23) is provided between the outlet of the low-pressure section refrigerant pump (21) and the spray pipe of the high-pressure section evaporator (13). A low-temperature refrigerant water throttling pipe (16) is provided between the bottom of the liquid bladder of the high-pressure section evaporator (13) and the spray pipe of the low-pressure section evaporator (19). A high-temperature refrigerant water throttling pipe (24) led out from the bottom of the liquid bladder of the condenser (1) is connected to the flash tube of the low-pressure section evaporator (19). The high-concentration solution circulation of the two-stage lithium bromide absorption heat pump unit with evaporation and absorption segmentation includes the first-stage generator (5), the low-pressure section secondary absorber (18), the high-pressure section secondary absorber (14), and the first-stage heat exchanger (11). The concentrated solution of the first-stage generator (5) is lifted by the first-stage concentrated solution pump (9), cooled by the first-stage heat exchanger (11), and enters the low-pressure section secondary absorber (18) to absorb the refrigerant vapor evaporated by the low-pressure section evaporator (19) to become a low-concentration intermediate solution. The intermediate solution is pumped by the intermediate solution pump (20) into the high-pressure section secondary absorber (14) to continue absorbing the refrigerant vapor evaporated by the high-pressure section evaporator (13) to become a dilute solution. The dilute solution is lifted by the high-pressure section secondary dilute solution pump (15), heated by the first-stage heat exchanger (11), and enters the first-stage generator (5) to be concentrated into a high-concentration concentrated solution. The low-concentration solution circulation of the two-stage lithium bromide absorption heat pump unit with evaporation and absorption segmentation includes the secondary generator (2), the primary absorber (6), and the secondary heat exchanger (12). The concentrated solution in the secondary generator (2) is cooled by the secondary heat exchanger (12) due to pressure and height differences and flows into the primary absorber (6) to absorb the refrigerant vapor generated by the primary generator (5) and become a low-concentration dilute solution. The low-concentration dilute solution is lifted by the primary dilute solution pump (10), heated by the secondary heat exchanger (12), and enters the secondary generator (2) to be concentrated into a higher concentration solution. The refrigerant circulation process of the two-stage lithium bromide absorption heat pump unit with evaporation and absorption is as follows: the high-temperature refrigerant vapor generated by the secondary generator (2) enters the condenser (1) and is condensed into high-temperature refrigerant water. The high-temperature refrigerant water enters the low-pressure section evaporator (19) through the high-temperature refrigerant water throttling pipe (24) and flashes. The refrigerant water that does not flash enters the liquid sac of the low-pressure section evaporator (19) and is pumped into the high-pressure section evaporator (13) by the low-pressure section refrigerant pump (21) and evaporates into refrigerant vapor I. The unevaporated refrigerant water enters the liquid sac of the high-pressure section evaporator (13) and enters the low-pressure section evaporator through the low-temperature refrigerant water throttling pipe (16) by the power of pressure difference and height difference. The refrigerant vapor II is evaporated by the device (19) into refrigerant vapor II; the refrigerant vapor II is absorbed by the high-concentration concentrated solution from the first-stage generator (5) to become an intermediate solution, the refrigerant vapor I is absorbed by the intermediate solution from the low-pressure section secondary absorber (18) to become the dilute solution, the dilute solution enters the first-stage generator (5) to concentrate and generate low-temperature refrigerant vapor, which enters the first-stage absorber (6), the low-temperature refrigerant vapor is absorbed by the higher-concentration concentrated solution from the secondary generator (2) to become the low-concentration dilute solution, the low-concentration dilute solution is pumped into the secondary generator (2) by the first-stage dilute solution pump (10) to concentrate and generate high-temperature refrigerant vapor, and so on in a continuous cycle.

2. The two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption stages according to claim 1, characterized in that, The driving heat source (25) is connected in series and enters the heat transfer tube of the secondary generator (2) and the heat transfer tube of the primary generator (5) in sequence; Alternatively, the driving heat source (25) may be connected in parallel to the heat transfer tube of the secondary generator (2) and the heat transfer tube of the primary generator (5).

3. The two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption stages according to claim 2, characterized in that, The low-temperature waste heat source (26) is connected in series and enters the heat transfer tube of the high-pressure section evaporator (13) and the heat transfer tube of the low-pressure section evaporator (19) in sequence.

4. The two-stage, first-class lithium bromide absorption heat pump unit with evaporation and absorption stages according to claim 3, characterized in that, The medium-temperature hot water (27) first enters in parallel into the heat transfer tube of the high-pressure section secondary absorber (14) and the heat transfer tube of the low-pressure section secondary absorber (18), and then enters in series into the heat transfer tube of the primary absorber (6) and the heat transfer tube of the condenser (1).

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