Two-stage second-type lithium bromide absorption heat pump steam unit with evaporation and absorption multi-processes

Abstract

The present application relates to a kind of two-stage type second kind lithium bromide absorption heat pump steam unit of steam absorption multi-flow, high temperature evaporator and high temperature absorber, low temperature evaporator and low temperature absorber are arranged in same cylinder, high temperature evaporator and high temperature absorber in same cavity, low temperature evaporator and low temperature absorber in same cavity, and high temperature evaporator and low temperature absorber are adjacent in middle, the heat transfer tube of high temperature evaporator and low temperature absorber is divided into multiple flows respectively, and the flow number of both is same, steam absorption before pipe box and steam absorption after pipe box are separated into corresponding multiple independent chambers according to the flow number of heat transfer tube.The steam absorption multi-flow of the present application makes small flow and small temperature difference of internal circulation hot water, can provide higher internal circulation hot water temperature, makes evaporation temperature, absorption pressure increase, produces higher grade saturated steam, satisfies the demand of user.

Description

Technical Field

[0001] This invention relates to the field of heating, ventilation and air conditioning equipment technology, and specifically to a two-stage type II lithium bromide absorption heat pump steam unit with multiple evaporation and absorption processes. Background Technology

[0002] Existing type II lithium bromide absorption heat pump steam units, such as Figure 1 As shown, it can deeply recover and utilize the heat from waste heat sources, producing corresponding saturated steam 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, which 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 high-grade saturated steam for users, achieving better economic and social benefits.

[0003] However, in practical applications, based on parameter conditions and heat pump feasibility, the temperature difference for internal circulating hot water is generally selected to be around 15℃. A larger internal circulating hot water flow rate and temperature difference result in a correspondingly larger power consumption and pump footprint for the internal circulating hot water system. To reduce the power consumption and pump size, the internal circulating hot water flow rate needs to be reduced, which in turn requires increasing the internal circulating hot water temperature difference. This means that for a given temperature at the inlet of the internal circulating hot water to the low-temperature absorber, the outlet temperature needs to be increased. This leads to a reduction in the heat exchange temperature difference at the end of the low-temperature absorber, worsening the unit's operating conditions and directly affecting the unit's variable operating performance and stability. Furthermore, when the waste heat source grade and the amount of recovered waste heat are constant, further improving the grade of the produced saturated steam is impossible due to the limitations imposed by the internal circulating 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-grade saturated steam 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 steam unit with multiple steam absorption processes, which 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, recover waste heat more deeply to produce higher-grade saturated steam, and has a compact structure.

[0005] The objective of this invention is achieved as follows: A two-stage, multi-stage, second-class lithium bromide absorption heat pump steam unit with multiple evaporation and absorption processes includes a vapor-liquid separator, 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 internal circulation hot water system, and an internal circulation hot water pump. The high-temperature evaporator and high-temperature absorber, and the low-temperature evaporator and low-temperature absorber are placed in the same cylinder, 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 vapor-liquid separator is placed above the high-temperature absorber, and the liquid outlet and inlet of the vapor-liquid separator are naturally circulated with the high-temperature absorber by the height difference and pressure difference. The heat transfer tubes of the high-temperature evaporator and the low-temperature absorber are divided into multiple channels, and the number of channels is the same for both. 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 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.

[0007] 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.

[0008] 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.

[0009] Preferably, the internally circulating hot water completes a heating process every two passes in the low-temperature absorber heat transfer tubes and a cooling process every two passes in the high-temperature evaporator heat transfer tubes. This multiple evaporation and absorption process allows the internally circulating hot water to undergo small heating in the low-pressure absorber heat transfer tubes and small cooling in the high-temperature evaporator heat transfer tubes, completing the entire heat absorption and release process. This enables the internally circulating hot water to achieve a small flow rate and a small temperature difference.

[0010] The beneficial effects of this invention are: This invention discloses a two-stage, multi-pass, type II lithium bromide absorption heat pump steam unit. Through the aforementioned novel process and structure, it overcomes the drawbacks of existing two-stage type II heat pump steam units that require large flow rates and large temperature differences for internal circulating hot water. It also eliminates the need for a vapor-liquid separator and a high-temperature hot water circulation pump, allowing the high-temperature hot water to circulate naturally. This enables the internal circulating hot water to complete the entire heat absorption and release process through multiple small-scale temperature increases and decreases at a low flow rate. The flow rate of the internal circulating hot water is determined based on the temperature difference between the internal circulating hot water and the temperature difference, 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 multiple small temperature increases and decreases in the internal circulation hot water can provide a higher internal circulation hot water temperature, thereby increasing the evaporation temperature and absorption pressure, producing higher-quality saturated steam to meet user needs. Alternatively, when producing saturated steam of the same quality, it can recover waste heat more deeply, reduce thermal pollution, and protect the ecological environment. Moreover, this two-stage heat pump steam unit has an integrated structure, occupies a small area, is easy to operate, and has a novel and compact appearance. Attached Figure Description

[0011] Figure 1 This is a flowchart of the existing Class II lithium bromide absorption heat pump steam unit.

[0012] Figure 2 This is a flowchart illustrating the working process of the two-stage, second-type lithium bromide absorption heat pump steam unit with multiple evaporation and absorption stages according to the present invention.

[0013] In the diagram: 1. High-temperature generator; 2. High-temperature condenser; 3. Cooling water inlet; 4. High-temperature heat exchanger; 5. Steam makeup water inlet; 6. Saturated steam 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)th process of high-temperature evaporator; 25. First process of low-temperature absorber; 26. Second process of low-temperature absorber; 27. Third process of low-temperature absorber; 28. Fifth process of low-temperature absorber; 29. ​​(n-1)th process of low-temperature absorber; 30. (n)th process of low-temperature absorber; 31. Vapor-liquid separator; 32. Liquid outlet pipe. Implementation

[0014] See Figure 2 This invention relates to a two-stage, multi-stage, type II lithium bromide absorption heat pump steam unit, comprising a vapor-liquid separator 32, 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 internal circulation hot water system 12, an internal circulation 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 pump steam units such as... Figure 1 Based 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 vapor-liquid separator 32 is located above the high-temperature absorber 7, and the liquid outlet and inlet of the vapor-liquid separator 32 circulate naturally with the high-temperature absorber 7 through height and pressure differences. 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, steam makeup water, and the produced high-grade saturated steam link the high-temperature cycle and the low-temperature cycle together, forming a two-stage Class II heat pump steam unit.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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 it enters the high-temperature evaporator in the first process 19 and the second process 20 for a slight temperature decrease; then it enters the low-temperature absorber in the third process 27 and the fourth process 28 for a slight temperature increase; then it enters the high-temperature evaporator in the third process 21 and the fourth process 22 for a slight temperature decrease; ... then it enters the low-temperature absorber in the (n-1)th process 30 and the low-temperature absorber... The internal circulating hot water undergoes a slight temperature increase in the low-temperature absorber (process 31) and a slight temperature decrease in the high-temperature evaporator (process 23, n-1) and high-temperature evaporator (process 24). This demonstrates that the internal circulating hot water completes a temperature increase every two processes in the low-temperature absorber (process 11) and a temperature decrease every two processes in the high-temperature evaporator (process 8). This multi-process evaporation and absorption configuration ensures that the internal circulating hot water undergoes a slight temperature increase in the low-pressure absorber (process 11) and a slight temperature decrease in the high-temperature evaporator (process 8), completing the entire heat absorption and release process. This results in a small flow rate and a small temperature difference for the internal circulating hot water.

[0019] 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 for heat release and cooling, and then flows out of the heat pump from waste heat source outlet 15. Alternatively, the waste heat source can be connected in parallel into the heat transfer tubes of high-temperature generator 1, low-temperature generator 18, and low-temperature evaporator 10 for heat release and cooling, or it can be connected in series, first into low-temperature evaporator 10, then into high-temperature generator 1, and finally into the heat transfer tubes of low-temperature generator 18 for heat release and cooling; cooling water is connected in series from... Cooling water inlet 3 sequentially enters 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 through cooling water outlet 16. Cooling water can also enter the heat transfer tubes of high-temperature condenser 2 and low-temperature condenser 17 in parallel to remove heat. Steam makeup water flows from steam makeup water inlet 5 into the bottom of vapor-liquid separator 32, and flows through liquid outlet pipe 33 into the heat transfer tubes of high-temperature absorber 7 to absorb heat and increase temperature. The vapor-liquid mixture then flows into vapor-liquid separator 32, and the high-grade saturated steam separated flows out of the unit through saturated steam outlet 6.

[0020] 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, multi-stage, second-type lithium bromide absorption heat pump steam unit, comprising a vapor-liquid separator, 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 internal circulating hot water system, and an internal circulating hot water pump, characterized in that: The high-temperature evaporator and high-temperature absorber, and the low-temperature evaporator and low-temperature absorber are placed in the same cylinder, 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 vapor-liquid separator is placed above the high-temperature absorber, and the liquid outlet and inlet of the vapor-liquid separator are naturally circulated with the high-temperature absorber by the height difference and pressure difference. The heat transfer tubes of the high-temperature evaporator and the low-temperature absorber are divided into multiple channels, and the number of channels is the same for both. 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. 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. 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 then enters the (n-1)th and nth stages of the high-temperature evaporator for a slight temperature decrease.

2. The two-stage, second-type lithium bromide absorption heat pump steam unit with multiple steam absorption stages according to claim 1, 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.

3. The two-stage, second-type lithium bromide absorption heat pump steam unit with multiple steam absorption stages according to claim 1, characterized in that: The internally circulating hot water completes a temperature rise every two passes in the low-temperature absorber heat transfer tubes and a temperature drop every two passes in the high-temperature evaporator heat transfer tubes. This multiple absorption and evaporation process allows the internally circulating hot water to undergo small temperature rises in the low-pressure absorber heat transfer tubes and small temperature drops in the high-temperature evaporator heat transfer tubes, completing the entire heat absorption and release process. This enables the internally circulating hot water to achieve a small flow rate and a small temperature difference.

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