Multi-effect lithium bromide absorption heat pump unit

Abstract

The application relates to a multi-effect lithium bromide absorption heat pump unit and belongs to the technical field of energy saving and environmental protection. The application solves the problem of low waste water heat recovery efficiency when the existing flash evaporation technology is combined with a heat pump unit. The first to the Nth effect evaporators are connected to the flash evaporation steam outlets of the multi-effect flash evaporator through steam channels one by one, the steam outlets of the first to the Nth effect evaporators are connected to the steam inlets of the first to the Nth effect absorbers, the steam outlet of the generator is connected to the steam inlet of the condenser, the water to be heated enters the Nth to the first effect absorbers, the condenser and is discharged in sequence through a water pipeline, a driving heat source pipeline is arranged in the generator, the lower part of the generator is connected to the upper parts of the first to the Nth effect absorbers through concentrated solution pipelines, the lower parts of the first to the Nth effect absorbers are connected to the upper part of the generator through dilute solution pipelines, and the lower part of the condenser is connected to the upper parts of the first to the Nth effect evaporators through refrigerant water pipelines.

Description

Technical Field

[0001] This invention relates to a multi-effect lithium bromide absorption heat pump unit, belonging to the field of energy-saving and environmental protection technology. Background Technology

[0002] In the fields of energy conservation, environmental protection, and waste heat recovery, heat pump technology is currently the primary method for wastewater waste heat recovery. A common approach involves exchanging heat with the wastewater using a clean intermediate water stream, and then recovering the waste heat through the intermediate water. With technological advancements, a direct-entry wastewater heat recovery method has emerged in recent years. This method combines a flash evaporator with a lithium bromide absorption heat pump unit. Utilizing the fact that water's boiling point decreases with decreasing environmental pressure, a negative pressure environment is artificially created, causing the wastewater to flash and generate clean steam that is directly delivered to the lithium bromide absorption unit. However, this technology still faces a significant challenge: the temperature difference between the flash evaporator's inlet and outlet water is only about 10°C, resulting in a relatively small waste heat recovery capacity. Summary of the Invention

[0003] The present invention aims to solve the problem of low wastewater waste heat recovery efficiency when using flash evaporation technology in combination with heat pump units, and provides a multi-effect lithium bromide absorption heat pump unit.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] A multi-effect lithium bromide absorption heat pump unit includes a multi-effect flash evaporator, a generator, a condenser, first to Nth effect evaporators, and first to Nth effect absorbers. The first to Nth effect evaporators are connected to the flash steam outlets of each effect of the multi-effect flash evaporator via steam channels. The steam outlets of the first to Nth effect evaporators are connected to the steam inlets of the first to Nth effect absorbers. The steam outlet of the generator is connected to the steam inlet of the condenser. Water to be heated enters the Nth to first effect absorbers and the condenser sequentially through water pipes and is then discharged. A driving heat source pipe is arranged inside the generator. The lower part of the generator is connected to the upper part of the first to Nth effect absorbers via concentrated solution pipes. The lower parts of the first to Nth effect absorbers are connected to the upper part of the generator via dilute solution pipes. The lower part of the condenser is connected to the upper part of the first to Nth effect evaporators via refrigerant water pipes. The lower parts of the first to Nth effect evaporators are connected to condensate water pipes.

[0006] Furthermore, a dilute solution pump is installed on the dilute solution pipeline, and a concentrated solution pump is installed on the concentrated solution pipeline.

[0007] Furthermore, a solution heat exchanger is provided between the dilute solution pipeline and the concentrated solution pipeline.

[0008] Furthermore, a refrigerant water pump is installed on the refrigerant water pipeline.

[0009] Furthermore, a condensate pump is installed on the condensate pipeline.

[0010] Furthermore, each evaporator is equipped with a first spray device at its top, and the refrigerant water pipeline is connected to the first spray device.

[0011] Furthermore, a second spray device is provided at the top of each absorber, and the concentrated solution pipeline is connected to the second spray device.

[0012] Furthermore, a steam inlet chamber is connected to one end of the tube side of each effect evaporator, and the flash steam outlet of each effect is connected to the tube side of the evaporator through the steam inlet chamber.

[0013] Furthermore, the other end of the tube side of each evaporator is connected to a waste steam condensate chamber.

[0014] A multi-effect lithium bromide absorption heat pump unit includes a multi-effect flash evaporator, first to Nth effect evaporators, first to Nth effect absorbers, first to Nth effect generators, and first to Nth effect condensers. The first to Nth effect evaporators are connected to the flash steam outlets of each effect of the multi-effect flash evaporator via corresponding steam channels. The steam outlets of the first to Nth effect evaporators are connected to the steam inlets of the first to Nth effect absorbers. The steam outlets of the first to Nth effect generators are connected to the steam inlets of the first to Nth effect condensers. Water to be heated is sequentially supplied through water pipes. After entering the Nth to the first effect absorber and the Nth to the first effect condenser, the solution is discharged. Each effect generator is equipped with a driving heat source pipeline. The lower part of the first to the Nth effect generators is connected to the upper part of the first to the Nth effect absorber through a concentrated solution pipeline. The lower part of the first to the Nth effect absorber is connected to the upper part of the first to the Nth effect generator through a dilute solution pipeline. The lower part of the first to the Nth effect condenser is connected to the upper part of the first to the Nth effect evaporator through a refrigerant water pipeline. The lower part of the first to the Nth effect evaporator is connected to a condensate water pipeline.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] In this application, different evaporators and absorbers are set up for different qualities of waste steam heat, which ensures the efficient recovery and utilization of waste steam heat of two different qualities. At the same time, the whole system shares a generator and condenser, which greatly reduces the product's size and floor space, greatly improves the efficiency of wastewater heat recovery and utilization, and significantly improves the product's performance.

[0017] The advantages of this application are:

[0018] First, it improves the performance of the flash evaporator. Under the same temperature drop of the wastewater, it generates two streams of clean exhaust steam of different qualities, and recovers heat energy in stages, thereby improving the recovery efficiency of wastewater heat.

[0019] Secondly, it significantly increases the temperature difference for wastewater recovery. The original flash evaporator had a single-chamber structure, with a maximum inlet and outlet temperature difference of about 10°C. The modified flash evaporator has a multi-chamber, multi-effect structure, which can increase the maximum inlet and outlet temperature difference of wastewater by at least 100%, thus improving the overall waste heat recovery capacity. The waste heat recovery of wastewater that required two devices in the existing technology can be completed by a single heat pump unit of this application, which greatly reduces equipment investment costs and saves floor space.

[0020] Third, the structure inside the absorption chiller has been optimized. Under the condition of recovering the same amount of waste heat, the equipment structure is more compact compared to the original technology, reducing the external size and floor space of the equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structural composition of this application.

[0022] In the picture:

[0023] 1. Multi-effect flash evaporator; 1-1. Demister; 1-2. Wastewater inlet; 1-3. Wastewater outlet; 1-4. First-effect flash chamber; 1-5. Second-effect flash chamber;

[0024] 2. Generator; 3. Condenser; 4. Evaporator; 4-1. First spray device;

[0025] 5. Absorber; 5-1. Second spray device;

[0026] 6. Steam passage; 7. Water pipeline; 8. Drive heat source pipeline; 9. Concentrated solution pipeline; 10. Dilute solution pipeline; 11. Refrigerant water pipeline; 12. Condensate pipeline; 13. Dilute solution pump; 14. Concentrated solution pump; 15. Solution heat exchanger; 16. Refrigerant water pump; 17. Condensate pump. Detailed Implementation

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] Specific implementation method one: Combining Figure 1 This embodiment describes a multi-effect lithium bromide absorption heat pump unit, comprising a multi-effect flash evaporator 1, a generator 2, a condenser 3, first to Nth effect evaporators 4, and first to Nth effect absorbers 5. The first to Nth effect evaporators 4 are connected one-to-one to the flash steam outlet of each effect of the multi-effect flash evaporator 1 via a steam channel 6. The steam outlets of the first to Nth effect evaporators 4 are connected to the steam inlets of the first to Nth effect absorbers 5. The steam outlet of the generator 2 is connected to the steam inlet of the condenser 3. Water to be heated is fed through a water... Pipeline 7 sequentially enters the Nth to the first-effect absorber 5 and condenser 3 and then exits. The generator 2 is equipped with a driving heat source pipeline 8. The lower part of the generator 2 is connected to the upper part of the first to the Nth-effect absorbers 5 through concentrated solution pipeline 9. The lower parts of the first to the Nth-effect absorbers 5 are connected to the upper part of the generator 2 through dilute solution pipeline 10. The lower part of the condenser 3 is connected to the upper part of the first to the Nth-effect evaporators 4 through refrigerant water pipeline 11. The lower parts of the first to the Nth-effect evaporators 4 are connected to condensate water pipeline 12.

[0030] The number of flash chambers in the multi-effect flash evaporator 1 corresponds to the number of effects of the multi-effect flash evaporator 1. In this application, a two-effect flash evaporator 1 is preferred, and the corresponding number of evaporators 4 is also two.

[0031] This application optimizes the structure of the flash evaporator 1 by dividing the flash chamber into two or more flash chambers, enabling the flash evaporator 1 to output multiple streams of clean exhaust steam of different qualities into the heat pump evaporator 4. Since different qualities of exhaust steam correspond to different negative pressure environments, the internal structure of the lithium bromide absorption chiller is also optimized and upgraded, with multiple evaporators 4 and multiple absorbers 5 respectively, to meet the absorption chiller's requirement for the utilization of waste heat from clean exhaust steam of different qualities generated by the flash evaporator 1.

[0032] In this application, different evaporators 4 and absorbers 5 are set up for different qualities of waste steam heat, which ensures efficient recovery and utilization of waste steam heat of two different qualities. At the same time, the whole system shares a generator 2 and condenser 3, which greatly reduces the product's size and floor space, greatly improves the efficiency of wastewater heat recovery and utilization, and significantly improves the product's performance.

[0033] The advantages of this application are:

[0034] First, it improves the performance of flash evaporator 1. Under the same temperature drop of wastewater, it generates two streams of clean exhaust steam of different qualities, and recovers heat energy in stages, thereby improving the recovery efficiency of wastewater waste heat.

[0035] Secondly, it significantly increases the temperature difference for wastewater recovery. The original flash evaporator 1 had a single-chamber structure, with a maximum inlet and outlet temperature difference of about 10°C. However, the modified flash evaporator 1 has a multi-chamber, multi-effect structure, which can increase the maximum inlet and outlet temperature difference of wastewater by at least 100%, thus improving the overall waste heat recovery capacity. The waste heat recovery of wastewater that required two devices in the existing technology can be completed by a single heat pump unit of this application, which greatly reduces equipment investment costs and saves floor space.

[0036] Third, the structure inside the absorption chiller has been optimized. Under the condition of recovering the same amount of waste heat, the equipment structure is more compact compared to the original technology, reducing the external size and floor space of the equipment.

[0037] Each flash steam outlet of flash evaporator 1 is connected to the multi-effect evaporator 4 via a steam channel 6. Alternatively, the structure can be adjusted so that each flash steam outlet of flash evaporator 1 is connected to the same evaporator 4 via a steam channel 6. To better utilize the flash steam, two sets of steam channels 6 can be separately arranged within one evaporator 4 to further improve space utilization. The number and structure of absorbers 5 are the same as those of evaporators 4; that is, when two sets of steam channels 6 are separately arranged within evaporators 4, two sets of steam channels 6 are also separately arranged within absorbers 5, corresponding one-to-one with the two steam outlets of evaporators 4.

[0038] A dilute solution pump 13 is installed on the dilute solution pipeline 10, and a concentrated solution pump 14 is installed on the concentrated solution pipeline 9. This design facilitates the transport of the dilute solution in the dilute solution pipeline 10 and the concentrated solution in the concentrated solution pipeline 9 by providing the dilute solution pump 13 and the concentrated solution pump 14.

[0039] A solution heat exchanger 15 is connected between the dilute solution pipeline 10 and the concentrated solution pipeline 9. This design enables heat exchange between the dilute solution in the dilute solution pipeline 10 and the concentrated solution in the concentrated solution pipeline 9. By transferring heat from the concentrated solution side to the dilute solution side, resource waste is avoided, thereby further improving heat exchange efficiency.

[0040] A refrigerant water pump 16 is installed on the refrigerant water pipeline 11. This design facilitates the delivery of refrigerant water by installing the refrigerant water pump 16.

[0041] A condensate pump 17 is installed on the condensate pipe 12. This design facilitates the discharge of condensate from the first to the Nth effect evaporators 4.

[0042] Each evaporator 4 is equipped with a first spray device 4-1 at its top, and the refrigerant water pipeline 11 is connected to the first spray device 4-1. This design facilitates more uniform entry of refrigerant water into the shell side of the evaporator 4, thereby achieving more uniform evaporative heat exchange and further improving heat exchange efficiency.

[0043] Each absorber 5 is equipped with a second spray device 5-1 at its top, and the concentrated solution pipeline 9 is connected to the second spray device 5-1. This design facilitates a more uniform entry of the concentrated solution into the absorber 5, thereby achieving more uniform evaporative heat exchange and further improving heat exchange efficiency.

[0044] Each effect evaporator 4 has a steam inlet chamber connected to one end of its inner tube side, and the flash steam outlet of each effect is connected to the tube side of evaporator 4 through the steam inlet chamber. This design, by setting up the steam inlet chamber, facilitates more uniform entry of flash steam into the tube side of evaporator 4, thereby achieving more uniform evaporation heat exchange and further improving heat exchange efficiency.

[0045] Each evaporator 4 has an exhaust steam condensate chamber connected to the other end of its inner tube side. This design connects the exhaust steam condensate chamber to the condensate pipe 12.

[0046] Process flow:

[0047] 1. Wastewater waste heat recovery process: Wastewater first enters the first-effect flash chamber 1-4 through wastewater inlet 1-2. Clean exhaust steam is generated under the negative pressure environment corresponding to the first-effect flash chamber 1-4. The small droplets carried by the exhaust steam are removed by the first-effect demister 1-1 and enter the first-effect evaporator 4 through the first-effect steam channel 6. In the first-effect evaporator 4, the heat is dissipated to the refrigerant water. The exhaust steam is cooled down and condensed into condensate. The condensate is discharged through the condensate outlet via the condensate pump 17 and finally discharged from the condensate outlet, thus completing the wastewater waste heat recovery of the first effect. Simultaneously, the wastewater, after flash cooling in the first-effect flash chamber 1-4, enters the second-effect flash chamber 1-5. Under the negative pressure environment corresponding to the second-effect flash chamber 1-5, clean exhaust steam is generated. This steam passes through the second-effect demister 1-1 to remove small droplets and enters the second-effect evaporator 4 through the second-effect steam channel 6. In the evaporator 4, heat is dissipated to the refrigerant water, and the exhaust steam cools and condenses into condensate. The condensate is then pumped through the condensate outlet 17 and finally discharged from the condensate outlet, thus completing the waste heat recovery of the second-effect wastewater. The wastewater, cooled by waste heat recovery, is discharged through wastewater outlet 1-3, completing one wastewater waste heat recovery process.

[0048] 2. Working fluid (refrigerant water / lithium bromide solution) process: Liquid refrigerant water evaporates into refrigerant water vapor in the first-effect evaporator 4 and the second-effect evaporator 4. The refrigerant water vapor enters the first-effect absorber 5 and the second-effect absorber 5 respectively. In these absorbers, the lithium bromide concentrate entering from the concentrated solution inlet releases heat to the water to be heated (the water to be heated is heated for the first and second times). The lithium bromide concentrate after absorbing the refrigerant water vapor becomes a lithium bromide dilute solution, which is discharged from the dilute solution outlet. After passing through the dilute solution pump and the solution heat exchanger 15, it enters the generator 2 through the dilute solution inlet. In the generator 2, the lithium bromide dilute solution evaporates into refrigerant water vapor under the action of an external driving heat source, becoming a lithium bromide concentrate. The concentrate is then discharged from the concentrate outlet, the solution heat exchanger 15, and the concentrate pump, and re-enters the absorber 5 through the concentrate inlet. Meanwhile, the refrigerant water vapor generated in generator 2 enters condenser 3, where it transfers heat to the water to be heated (the water to be heated for the third time), cools down and condenses into refrigerant water, and then re-enters the first-effect evaporator 4 and the second-effect evaporator 4 through the refrigerant outlet and the refrigerant pump, to continue absorbing waste heat from the wastewater.

[0049] 3. Driving heat source process: The driving heat source enters the driving heat source pipeline 8 in the generator 2 through the driving heat source inlet, transfers heat to the lithium bromide dilute solution, and then discharges through the driving heat source outlet.

[0050] 4. Hot water process: The hot water that needs to be heated enters the second-effect absorber 5 through the hot water inlet for the first heating, then enters the first-effect absorber 5 for the second heating, then enters the condenser 3 for the third heating, and finally is discharged through the hot water outlet.

[0051] Specific Implementation Method Two: Combining Figure 1This embodiment describes a multi-effect lithium bromide absorption heat pump unit, comprising a multi-effect flash evaporator 1, first to Nth effect evaporators 4, first to Nth effect absorbers 5, first to Nth effect generators 2, and first to Nth effect condensers 3. The first to Nth effect evaporators 4 are connected one-to-one to the flash steam outlet of each effect of the multi-effect flash evaporator 1 via steam channels 6. The steam outlets of the first to Nth effect evaporators 4 are connected to the steam inlets of the first to Nth effect absorbers 5. The steam outlets of the first to Nth effect generators 2 are connected to the steam inlets of the first to Nth effect condensers 3. Water to be heated is supplied via water pipes 7. After entering the Nth to the first-effect absorber 5 and the Nth to the first-effect condenser 3, the water is discharged. Each generator 2 is equipped with a driving heat source pipe 8. The lower part of the first to the Nth-effect generator 2 is connected to the upper part of the first to the Nth-effect absorber 5 via a concentrated solution pipe 9. The lower part of the first to the Nth-effect absorber 5 is connected to the upper part of the first to the Nth-effect generator 2 via a dilute solution pipe 10. The lower part of the first to the Nth-effect condenser 3 is connected to the upper part of the first to the Nth-effect evaporator 4 via a refrigerant water pipe 11. The lower part of the first to the Nth-effect evaporator 4 is connected to a condensate water pipe 12. The water to be heated enters the Nth to the first-effect absorber 5 and the Nth to the first-effect condenser 3 sequentially via a water pipe 7 and is then discharged. This cascaded heat recovery achieves four heating stages for the water to be heated, effectively improving the waste heat recovery efficiency of the wastewater.

[0052] Each dilute solution pipeline 10 is equipped with a dilute solution pump 13, and each concentrated solution pipeline 9 is equipped with a concentrated solution pump 14. This design facilitates the transfer of dilute solution in the dilute solution pipeline 10 and concentrated solution in the concentrated solution pipeline 9 by providing dilute solution pumps 13 and 14.

[0053] Each dilute solution pipeline 10 and each concentrated solution pipeline 9 is connected to a corresponding solution heat exchanger 15. This design enables heat exchange between the dilute solution in the dilute solution pipeline 10 and the concentrated solution in the concentrated solution pipeline 9. By transferring the heat from the concentrated solution to the dilute solution side through the solution heat exchanger 15, resource waste is avoided, thereby further improving heat exchange efficiency.

[0054] Each refrigerant water pipeline 11 is equipped with a refrigerant water pump 16. This design facilitates the delivery of refrigerant water by installing the refrigerant water pump 16.

[0055] Each condensate pipe 12 is equipped with a condensate pump 17. This design facilitates the drainage of condensate from the first to the Nth effect evaporators 4.

[0056] Each evaporator 4 is equipped with a first spray device 4-1 at its top, and the refrigerant water pipeline 11 is connected to the first spray device 4-1. This design facilitates more uniform entry of refrigerant water into the shell side of the evaporator 4, thereby achieving more uniform evaporative heat exchange and further improving heat exchange efficiency.

[0057] Each absorber 5 is equipped with a second spray device 5-1 at its top, and the concentrated solution pipeline 9 is connected to the second spray device 5-1. This design facilitates a more uniform entry of the concentrated solution into the absorber 5, thereby achieving more uniform evaporative heat exchange and further improving heat exchange efficiency.

[0058] Each effect evaporator 4 has a steam inlet chamber connected to one end of its inner tube side, and the flash steam outlet of each effect is connected to the tube side of evaporator 4 through the steam inlet chamber. This design, by setting up the steam inlet chamber, facilitates more uniform entry of flash steam into the tube side of evaporator 4, thereby achieving more uniform evaporation heat exchange and further improving heat exchange efficiency.

[0059] Each evaporator 4 has an exhaust steam condensate chamber connected to the other end of its inner tube side. This design connects the exhaust steam condensate chamber to the condensate pipe 12.

[0060] Other components and connections are the same as in Specific Implementation Method 1.

Claims

1. A multi-effect lithium bromide absorption heat pump unit, characterized in that: The system includes a multi-effect flash evaporator (1), a generator (2), a condenser (3), first to Nth effect evaporators (4), and first to Nth effect absorbers (5). The first to Nth effect evaporators (4) are connected to the flash steam outlet of each effect of the multi-effect flash evaporator (1) through a steam channel (6). The steam outlets of the first to Nth effect evaporators (4) are connected to the steam inlets of the first to Nth effect absorbers (5). The steam outlet of the generator (2) is connected to the steam inlet of the condenser (3). The water to be heated enters the Nth to first effect absorbers sequentially through a water pipe (7). The heat source is discharged after the absorber (5) and condenser (3). The generator (2) is equipped with a driving heat source pipeline (8). The lower part of the generator (2) is connected to the upper part of the first to Nth effect absorbers (5) through the concentrated solution pipeline (9). The lower part of the first to Nth effect absorbers (5) is connected to the upper part of the generator (2) through the dilute solution pipeline (10). The lower part of the condenser (3) is connected to the upper part of the first to Nth effect evaporators (4) through the refrigerant water pipeline (11). The lower part of the first to Nth effect evaporators (4) is connected to the condensate water pipeline (12).

2. The multi-effect lithium bromide absorption heat pump unit according to claim 1, characterized in that: A dilute solution pump (13) is installed on the dilute solution pipeline (10), and a concentrated solution pump (14) is installed on the concentrated solution pipeline (9).

3. A multi-effect lithium bromide absorption heat pump unit according to claim 1 or 2, characterized in that: A solution heat exchanger (15) is provided between the dilute solution pipeline (10) and the concentrated solution pipeline (9).

4. A multi-effect lithium bromide absorption heat pump unit according to claim 1, characterized in that: A refrigerant water pump (16) is installed on the refrigerant water pipeline (11).

5. A multi-effect lithium bromide absorption heat pump unit according to claim 1, 2 or 4, characterized in that: A condensate pump (17) is installed on the condensate pipe (12).

6. A multi-effect lithium bromide absorption heat pump unit according to claim 1, characterized in that: Each evaporator (4) is equipped with a first spray device (4-1) at the top, and the refrigerant water pipeline (11) is connected to the first spray device (4-1).

7. A multi-effect lithium bromide absorption heat pump unit according to claim 1, characterized in that: Each absorber (5) is equipped with a second spray device (5-1) at its top, and the concentrated solution pipeline (9) is connected to the second spray device (5-1).

8. A multi-effect lithium bromide absorption heat pump unit according to claim 1, 2, 4, 6 or 7, characterized in that: Each effect evaporator (4) has a steam inlet chamber connected to one end of the tube side, and the flash steam outlet of each effect is connected to the tube side of the evaporator (4) through the steam inlet chamber.

9. A multi-effect lithium bromide absorption heat pump unit according to claim 8, characterized in that: Each evaporator (4) has a waste steam condensate chamber connected to the other end of its inner tube side.

10. A multi-effect lithium bromide absorption heat pump unit, characterized in that: The system includes a multi-effect flash evaporator (1), first to Nth effect evaporators (4), first to Nth effect absorbers (5), first to Nth effect generators (2), and first to Nth effect condensers (3). The first to Nth effect evaporators (4) are connected one-to-one to the flash steam outlet of each effect of the multi-effect flash evaporator (1) via steam channels (6). The steam outlets of the first to Nth effect evaporators (4) are connected to the steam inlets of the first to Nth effect absorbers (5). The steam outlets of the first to Nth effect generators (2) are connected to the steam inlets of the first to Nth effect condensers (3). The water to be heated enters the Nth to first effect absorbers sequentially via water pipes (7). 5) The Nth to the first effect condenser (3) are discharged. Each effect generator (2) is equipped with a driving heat source pipeline (8). The lower part of the first to the Nth effect generator (2) is connected to the upper part of the first to the Nth effect absorber (5) through the concentrated solution pipeline (9). The lower part of the first to the Nth effect absorber (5) is connected to the upper part of the first to the Nth effect generator (2) through the dilute solution pipeline (10). The lower part of the first to the Nth effect condenser (3) is connected to the upper part of the first to the Nth effect evaporator (4) through the refrigerant water pipeline (11). The lower part of the first to the Nth effect evaporator (4) is connected to the condensate water pipeline (12).

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