Two-stage type second lithium bromide absorption heat pump with internal circulation and multiple temperature rising and falling of hot water

Abstract

The present application relates to a kind of two-stage type second lithium bromide absorption heat pump of internal circulation hot water multiple temperature rise, including high temperature evaporator, high temperature absorber, high temperature generator, high temperature condenser, high temperature heat exchanger, low temperature evaporator, low temperature absorber, low temperature generator, low temperature condenser, low temperature heat exchanger, internal circulation hot water system and internal circulation hot water pump, high temperature evaporator and low temperature absorber heat transfer pipe are divided into multiple flows respectively, and the inside of steam absorption pipe box before and after is separated into corresponding multiple independent chambers according to the number of heat transfer pipe flow.The present application makes internal circulation hot water multiple temperature rise, greatly reduces the flow and temperature difference of internal circulation hot water, internal circulation hot water pump power consumption and pump body area are reduced, operation and investment cost are reduced, simultaneously, when waste heat source grade, preparation high temperature heat source grade is certain, internal circulation hot water multiple small temperature rise makes the working condition of heat pump unit better, and the working condition range is larger, performance is more stable and reliable.

Description

Technical Field

[0001] This invention relates to the field of heating, ventilation and air conditioning equipment technology, specifically to a two-stage type II lithium bromide absorption heat pump with multiple temperature rises and falls of internally circulating hot water. Background Technology

[0002] Existing Class II lithium bromide absorption heat pump units, such as Figure 1 As shown, it can deeply recover and utilize the heat from waste heat sources, and produce corresponding high-temperature heat sources under the condition of providing cooling water. Its working principle is to superimpose two ordinary Class II heat pumps to form a low-temperature circulating Class II heat pump and a high-temperature circulating Class II heat pump. The waste heat source is connected in series and enters the low-temperature evaporator, high-temperature generator, and the tubes of the low-temperature generator to release heat and cool down; the cooling water is connected in series and enters the tubes of the high-temperature condenser and low-temperature condenser to remove heat; the low-temperature absorber produces high-temperature internal circulating hot water and enters the tubes of the high-temperature evaporator. After the internal circulating hot water is cooled in the tubes of the high-temperature evaporator, it is pumped back into the tubes of the low-temperature absorber to be heated, forming an internal circulating hot water system. Because the temperature of the internal circulating hot water entering the high-temperature evaporator is about 50°C higher than that of the waste heat source outlet, it provides a higher absorption pressure for the high-temperature cycle, enabling the high-temperature absorber to produce a high-temperature heat source that is about 85°C higher than that of the waste heat source outlet, thus expanding the application scenarios of Class II heat pumps and achieving better economic and social benefits.

[0003] However, in practical applications, based on parameter conditions and heat pump feasibility, the temperature difference for internal circulation hot water is generally selected to be around 15℃. A larger internal circulation hot water flow rate and temperature difference result in a correspondingly larger power consumption and pump footprint for the internal circulation hot water system. To reduce the power consumption and pump size, the internal circulation hot water flow rate needs to be reduced, which in turn requires increasing the internal circulation hot water temperature difference. This means that when the internal circulation hot water enters the low-temperature absorber at a constant temperature, the exit temperature needs to be increased, leading to a reduced heat exchange temperature difference at the absorber's end. This worsens the unit's operating conditions, directly affecting the unit's variable operating performance and stability. Furthermore, when the waste heat source grade and recovered waste heat are constant, further improving the grade of the produced high-temperature heat source is impossible due to the limitations imposed by the internal circulation hot water temperature on the unit's solution temperature, pressure, and concentration. In response to this situation, how to reduce the flow rate and temperature difference of circulating hot water in the heat pump unit, reduce the power consumption and pump size of the hot water pump, reduce the operating and investment costs of the unit, and more deeply recover waste heat to produce higher quality heat sources has become one of the important research topics. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a two-stage second-type lithium bromide absorption heat pump that can reduce the internal circulation hot water flow rate and temperature difference, reduce the power consumption and pump size of the hot water pump, reduce the unit operation and investment costs, more deeply recover waste heat to produce higher quality heat sources, and has a compact structure for multiple temperature rises and falls of internal circulation hot water.

[0005] The objective of this invention is achieved as follows: A two-stage type II lithium bromide absorption heat pump with multiple temperature rises and falls for internally circulating hot water includes a high-temperature evaporator, a high-temperature absorber, a high-temperature generator, a high-temperature condenser, a high-temperature heat exchanger, a low-temperature evaporator, a low-temperature absorber, a low-temperature generator, a low-temperature condenser, a low-temperature heat exchanger, an internally circulating hot water system, and an internally circulating hot water pump. The high-temperature evaporator, high-temperature absorber, low-temperature evaporator, and low-temperature absorber are arranged in the same cylinder and separated by a partition. The high-temperature evaporator and the high-temperature absorber are in the same cavity, and the low-temperature evaporator and the low-temperature absorber are in the same cavity, with the high-temperature evaporator and the low-temperature absorber adjacent to each other in the middle. The heat transfer tubes of the high-temperature evaporator and the low-temperature absorber are divided into multiple channels. The front tube box of the high-temperature evaporator and the front tube box of the low-temperature absorber are set as a whole evaporation and absorption front tube box, and the rear tube box of the high-temperature evaporator and the rear tube box of the low-temperature absorber are set as a whole evaporation and absorption rear tube box. The interior of the evaporation and absorption front tube box and the evaporation and absorption rear tube box are divided into multiple independent chambers according to the number of heat transfer tube channels.

[0006] Preferably, the heat transfer tubes of the high-temperature evaporator and the low-temperature absorber have the same number of passes. The heat transfer tubes of the high-temperature evaporator are sequentially arranged as a first pass, a second pass, a third pass, a fourth pass, an (n-1)th pass, and an nth pass. The heat transfer tubes of the low-temperature absorber are sequentially arranged as a first pass, a second pass, a third pass, a fourth pass, a fifth pass, an (n-1)th pass, and an nth pass.

[0007] Preferably, the internal chambers of the pre-evaporation tube box are divided as follows: the first process of the low-temperature absorber is one chamber, the second process of the low-temperature absorber and the first process of the high-temperature evaporator are one chamber, the second process of the high-temperature evaporator and the third process of the low-temperature absorber are one chamber, the fourth process of the low-temperature absorber and the third process of the high-temperature evaporator are one chamber, the fourth process of the high-temperature evaporator and the fifth process of the low-temperature absorber are one chamber, and so on, with the nth process of the low-temperature absorber and the (n-1)th process of the high-temperature evaporator forming one chamber, and the nth process of the high-temperature evaporator forming one chamber.

[0008] Preferably, the internal chambers of the evaporation and absorption tube box are divided as follows: the first and second low-temperature absorber processes are in one chamber, the first and second high-temperature evaporator processes are in one chamber, the third and fourth low-temperature absorber processes are in one chamber, the third and fourth high-temperature evaporator processes are in one chamber, and so on, with the (n-1)th and nth low-temperature absorber processes in one chamber, and the (n-1)th and nth high-temperature evaporator processes in one chamber.

[0009] Preferably, after the internally circulating hot water exits the nth stage of the high-temperature evaporator, it is pumped in series by the internally circulating hot water pump and enters the first and second stages of the low-temperature absorber for a slight temperature increase, then enters the first and second stages of the high-temperature evaporator for a slight temperature decrease, then enters the third and fourth stages of the low-temperature absorber for a slight temperature increase, then enters the third and fourth stages of the high-temperature evaporator for a slight temperature decrease, ... then enters the (n-1)th and nth stages of the low-temperature absorber for a slight temperature increase, and finally enters the (n-1)th and nth stages of the high-temperature evaporator for a slight temperature decrease.

[0010] Preferably, the internally circulating hot water completes a temperature rise every two passes in the low-temperature absorber heat transfer tube and a temperature drop every two passes in the high-temperature evaporator heat transfer tube. In this way, multiple passes back and forth slightly raise the temperature in the low-pressure absorber heat transfer tube and slightly lower the temperature in the high-temperature evaporator heat transfer tube to complete the entire heat absorption and release process, so that the internally circulating hot water achieves a small flow rate and a small temperature difference.

[0011] The beneficial effects of this invention are: The present invention discloses a two-stage type II lithium bromide absorption heat pump with multiple temperature rises and falls in internal circulation. Through the above-mentioned novel process and structure, it overcomes the shortcomings of existing two-stage type II heat pumps that require large flow rate and large temperature difference for internal circulation hot water. This allows the internal circulation hot water to complete the entire heat absorption and release process with multiple small temperature rises and falls in small flow rate. The flow rate of the internal circulation hot water is selected based on the temperature rise and fall difference of the internal circulation hot water, the flow velocity in the heat transfer tube, and the number of passes. With a fixed load and heat exchange area, multiple small temperature fluctuations significantly reduce the flow rate of the internal circulating hot water, reduce the power consumption and pump footprint of the internal circulating hot water pump, and lower operating and investment costs. At the same time, with a fixed waste heat source quality and a fixed high-temperature heat source quality, multiple small temperature fluctuations of the internal circulating hot water improve the operating conditions of the heat pump unit, increase the range of operating conditions, and make its performance more stable and reliable. In addition, the new process and structure of internal circulation hot water with multiple small temperature increases and decreases can provide higher internal circulation hot water temperatures, thereby increasing evaporation temperature and absorption pressure, producing higher-quality high-temperature heat sources to meet users' needs for high-quality heat sources. Alternatively, when producing high-temperature heat sources of the same quality, it can recover waste heat sources more deeply, reduce thermal pollution, and protect the ecological environment. Moreover, this two-stage heat pump has an integrated structure, small footprint, simple operation, and a novel and compact appearance. Attached Figure Description

[0012] Figure 1 This is a flowchart of the operation of an existing Class II lithium bromide absorption heat pump unit.

[0013] Figure 2 This is a flowchart illustrating the working process of the two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases for internally circulating hot water according to the present invention.

[0014] In the diagram: 1. High-temperature generator; 2. High-temperature condenser; 3. Cooling water inlet; 4. High-temperature heat exchanger; 5. High-temperature heat source inlet; 6. High-temperature heat source outlet; 7. High-temperature absorber; 8. High-temperature evaporator; 9. Waste heat source inlet; 10. Low-temperature evaporator; 11. Low-temperature absorber; 12. Internal circulation hot water system; 13. Internal circulation hot water pump; 14. Low-temperature heat exchanger; 15. Waste heat source outlet; 16. Cooling water outlet; 17. Low-temperature condenser; 18. Low-temperature generator; 19. First process of high-temperature evaporator; 20. Second process of high-temperature evaporator; 21. Third process of high-temperature evaporator; 22. Fourth process of high-temperature evaporator; 23. (n-1)th process of high-temperature evaporator; 24. (n-1)th process of low-temperature absorber; 25. Second process of low-temperature absorber; 26. Third process of low-temperature absorber; 27. Fourth process of low-temperature absorber; 28. Fifth process of low-temperature absorber; 29. ​​(n-1)th process of low-temperature absorber; 30. (n-1)th process of low-temperature absorber; 31. Implementation

[0015] See Figure 2 This invention relates to a two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases in internally circulating hot water, comprising a high-temperature evaporator 8, a high-temperature absorber 7, a high-temperature generator 1, a high-temperature condenser 2, a high-temperature heat exchanger 4, a low-temperature evaporator 10, a low-temperature absorber 11, a low-temperature generator 18, a low-temperature condenser 17, a low-temperature heat exchanger 14, an internally circulating hot water system 12, an internally circulating hot water pump 13, a shielded pump, and piping, valves, and a control system connecting the various components. It is based on existing two-stage type II heat pumps such as... Figure 1Based on this, the high-temperature evaporator 8 and high-temperature absorber 7, and the low-temperature evaporator 10 and low-temperature absorber 11 are arranged in the same cylinder, separated by a partition. The high-temperature evaporator 8 and high-temperature absorber 7 are in the same cavity, and the low-temperature evaporator 10 and low-temperature absorber 11 are in the same cavity, with the high-temperature evaporator 8 and low-temperature absorber 11 adjacent to each other in the middle. The high-temperature evaporator 8, high-temperature absorber 7, high-temperature generator 1, high-temperature condenser 2, and high-temperature heat exchanger 4 constitute a high-temperature cycle Class II heat pump; the low-temperature evaporator 10, low-temperature absorber 11, low-temperature generator 18, low-temperature condenser 17, and low-temperature heat exchanger 14 constitute a low-temperature cycle Class II heat pump. The waste heat source of the external system, cooling water, internal circulating hot water, and the generated high-temperature heat source link the high-temperature cycle and the low-temperature cycle together, forming a two-stage Class II heat pump.

[0016] The heat transfer tubes of the high-temperature evaporator 8 and the low-temperature absorber 11 are divided into multiple channels, and the number of channels in both is the same. The front tube box of the high-temperature evaporator 8 and the front tube box of the low-temperature absorber 11 are set as a whole pre-evaporation tube box, and the rear tube box of the high-temperature evaporator 8 and the rear tube box of the low-temperature absorber 11 are set as a whole post-evaporation tube box. The interior of the pre-evaporation tube box and the post-evaporation tube box is divided into multiple independent chambers according to the number of heat transfer tube channels. The heat transfer tubes of the high-temperature evaporator 8 have multiple flows in sequence as follows: high-temperature evaporator first flow 19, high-temperature evaporator second flow 20, high-temperature evaporator third flow 21, high-temperature evaporator fourth flow 22, high-temperature evaporator (n-1)th flow 23, and high-temperature evaporator (n)th flow 24. The heat transfer tubes of the low-temperature absorber have multiple flows in sequence as follows: low-temperature absorber first flow 25, low-temperature absorber second flow 26, low-temperature absorber third flow 27, low-temperature absorber fourth flow 28, low-temperature absorber fifth flow 29, low-temperature absorber (n-1)th flow 30, and low-temperature absorber (n)th flow 31.

[0017] The internal chambers of the pre-evaporation tube box are divided as follows: the first process 25 of the low-temperature absorber is one chamber; the second process 26 of the low-temperature absorber and the first process 19 of the high-temperature evaporator are one chamber; the second process 20 of the high-temperature evaporator and the third process 27 of the low-temperature absorber are one chamber; the fourth process 28 of the low-temperature absorber and the third process 21 of the high-temperature evaporator are one chamber; the fourth process 22 of the high-temperature evaporator and the fifth process 29 of the low-temperature absorber are one chamber; and so on. The nth process 31 of the low-temperature absorber and the (n-1)th process 23 of the high-temperature evaporator are one chamber; and the nth process 24 of the high-temperature evaporator is one chamber.

[0018] The internal chambers of the evaporation and absorption tube box are divided as follows: the first process 25 and the second process 26 of the low-temperature absorber are in one chamber, the first process 19 and the second process 20 of the high-temperature evaporator are in one chamber, the third process 27 and the fourth process 28 of the low-temperature absorber are in one chamber, the third process 21 and the fourth process 22 of the high-temperature evaporator are in one chamber, and so on. The (n-1)th process 30 and the nth process 31 of the low-temperature absorber are in one chamber, and the (n-1)th process 23 and the nth process 24 of the high-temperature evaporator are in one chamber.

[0019] The working principle of the internal circulation hot water system 12: After exiting the high-temperature evaporator in the nth process 24, the internal circulation hot water is lifted by the internal circulation hot water pump 13 and sequentially enters the low-temperature absorber in the first process 25 and the second process 26 for a slight temperature increase, then enters the high-temperature evaporator in the first process 19 and the second process 20 for a slight temperature decrease, then enters the low-temperature absorber in the third process 27 and the fourth process 28 for a slight temperature increase, then enters the high-temperature evaporator in the third process 21 and the fourth process 22 for a slight temperature decrease, ... and enters the low-temperature absorber in the (n-1)th process. The internal circulating hot water undergoes a slight temperature increase in process 30 and process n 31 of the low-temperature absorber, and a slight temperature decrease in process n-1 23 of the high-temperature evaporator and process n 24 of the high-temperature evaporator. It can be seen that the internal circulating hot water completes a temperature increase every two processes in the heat transfer tube of the low-temperature absorber 11, and a temperature decrease every two processes in the heat transfer tube of the high-temperature evaporator 8. In this way, multiple processes go back and forth, with slight temperature increases in the heat transfer tube of the low-pressure absorber 11 and slight temperature decreases in the heat transfer tube of the high-temperature evaporator 8, to complete the entire heat absorption and release process, so that the internal circulating hot water achieves a small flow rate and a small temperature difference.

[0020] The waste heat source of the external system is connected in series from waste heat source inlet 9 into the heat transfer tubes of high temperature generator 1, low temperature generator 18, and low temperature evaporator 10 to release heat and cool down, and then flows out of the heat pump from waste heat source outlet 15. The waste heat source can also be connected in parallel into the heat transfer tubes of high temperature generator 1, low temperature generator 18, and low temperature evaporator 10 to release heat and cool down, or the waste heat source can be connected in series into the heat transfer tubes of low temperature evaporator 10 first, then high temperature generator 1, and finally low temperature generator 18 to release heat and cool down. The cooling water is connected in series from cooling water inlet 3 into the heat transfer tubes of high temperature condenser 2 and low temperature condenser 17 to remove heat, and then flows out of the heat pump from cooling water outlet 16. The cooling water can also be connected in parallel into the heat transfer tubes of high temperature condenser 2 and low temperature condenser 17 to remove heat. The high temperature heat source is connected from high temperature heat source inlet 5 into the heat transfer tubes of high temperature absorber 7 to raise the temperature, and then flows out of the heat pump from high temperature heat source outlet 6. The heated high temperature heat source is then sent to the user.

[0021] The waste heat source can be waste hot water, chemical materials, exhaust steam, multi-component steam, or other media.

[0022] The high-temperature heat source can be a medium such as high-temperature hot water or high-temperature chemical materials.

[0023] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases for internally circulating hot water, comprising a high-temperature evaporator, a high-temperature absorber, a high-temperature generator, a high-temperature condenser, a high-temperature heat exchanger, a low-temperature evaporator, a low-temperature absorber, a low-temperature generator, a low-temperature condenser, a low-temperature heat exchanger, an internally circulating hot water system, and an internally circulating hot water pump, characterized in that: The high-temperature evaporator, high-temperature absorber, low-temperature evaporator, and low-temperature absorber are placed in the same cylinder and separated by a partition. The high-temperature evaporator and high-temperature absorber are in the same chamber, and the low-temperature evaporator and low-temperature absorber are in the same chamber, with the high-temperature evaporator and low-temperature absorber adjacent to each other in the middle. The heat transfer tubes of the high-temperature evaporator and the low-temperature absorber are divided into multiple processes. The front tube box of the high-temperature evaporator and the front tube box of the low-temperature absorber are set into a whole evaporation and absorption front tube box. The rear tube box of the high-temperature evaporator and the rear tube box of the low-temperature absorber are set into a whole evaporation and absorption rear tube box. The interior of the evaporation and absorption front tube box and the evaporation and absorption rear tube box are divided into multiple independent chambers according to the number of heat transfer tube processes. The heat transfer tubes of the high-temperature evaporator and the low-temperature absorber have the same number of passes. The heat transfer tubes of the high-temperature evaporator have multiple passes in sequence as follows: high-temperature evaporator first pass, high-temperature evaporator second pass, high-temperature evaporator third pass, high-temperature evaporator fourth pass, high-temperature evaporator (n-1)th pass, and high-temperature evaporator (n)th pass. The heat transfer tubes of the low-temperature absorber have multiple passes in sequence as follows: low-temperature absorber first pass, low-temperature absorber second pass, low-temperature absorber third pass, low-temperature absorber fourth pass, low-temperature absorber fifth pass, low-temperature absorber (n-1)th pass, and low-temperature absorber (n)th pass. After exiting the high-temperature evaporator at the nth stage, the internally circulating hot water is pumped in series and enters the first and second stages of the low-temperature absorber for a slight temperature increase, then enters the first and second stages of the high-temperature evaporator for a slight temperature decrease, then enters the third and fourth stages of the low-temperature absorber for a slight temperature increase, then enters the third and fourth stages of the high-temperature evaporator for a slight temperature decrease, until it enters the (n-1)th and nth stages of the low-temperature absorber for a slight temperature increase, and finally enters the (n-1)th and nth stages of the high-temperature evaporator for a slight temperature decrease.

2. The two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases for internally circulating hot water according to claim 1, characterized in that: The internal chambers of the pre-evaporation tube box are divided as follows: the first process of the low-temperature absorber is one chamber, the second process of the low-temperature absorber and the first process of the high-temperature evaporator are one chamber, the second process of the high-temperature evaporator and the third process of the low-temperature absorber are one chamber, the fourth process of the low-temperature absorber and the third process of the high-temperature evaporator are one chamber, the fourth process of the high-temperature evaporator and the fifth process of the low-temperature absorber are one chamber, and so on, with the nth process of the low-temperature absorber and the (n-1)th process of the high-temperature evaporator being one chamber, and the nth process of the high-temperature evaporator being one chamber.

3. A two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases for internally circulating hot water, as described in claim 1 or 2, characterized in that: The internal chambers of the evaporation and absorption tube box are divided as follows: the first and second low-temperature absorber processes are in one chamber, the first and second high-temperature evaporator processes are in one chamber, the third and fourth low-temperature absorber processes are in one chamber, the third and fourth high-temperature evaporator processes are in one chamber, and so on, with the (n-1)th and nth low-temperature absorber processes in one chamber, and the (n-1)th and nth high-temperature evaporator processes in one chamber.

4. A two-stage type II lithium bromide absorption heat pump with multiple temperature increases and decreases for internally circulating hot water according to claim 1, characterized in that: The internally circulating hot water completes a temperature increase every two passes in the low-temperature absorber heat transfer tubes and a temperature decrease every two passes in the high-temperature evaporator heat transfer tubes. In this way, multiple passes back and forth, with small temperature increases in the low-pressure absorber heat transfer tubes and small temperature decreases in the high-temperature evaporator heat transfer tubes, to complete the entire heat absorption and release process, enabling the internally circulating hot water to achieve a small flow rate and a small temperature difference.

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