Low-temperature waste heat driven large temperature rise two-stage type lithium bromide absorption heat pump unit

Abstract

This invention relates to a low-temperature waste heat-driven, high-temperature-rise, two-stage type II lithium bromide absorption heat pump unit. Low-pressure exhaust steam enters the evaporator; a low-temperature waste heat source is connected in series, first entering the primary generator and then the heat transfer tubes of the secondary generator; low-temperature cooling water is connected in series, first entering the condenser and then the primary absorber. This invention does not consume high-temperature energy; it is driven by a low-temperature waste heat source. Under the condition of providing low-temperature cooling water, it deeply recovers and utilizes the waste heat from the low-temperature waste heat source (waste water below 55°C and exhaust steam with a pressure below 16 kPa·A, etc.) to produce medium-temperature hot water with a higher outlet temperature than the low-temperature waste heat source. This hot water can be used for centralized heating in winter, preheating of cold sources in production processes, or for use in areas requiring antifreeze. It achieves 100% energy saving, reduces waste heat emissions, and realizes green and environmentally friendly economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to a low-temperature waste heat driven large temperature rise two-stage type second lithium bromide absorption heat pump unit, belonging to the technical field of heating, ventilation and air conditioning. BACKGROUND

[0002] In the production process or life, medium-temperature hot water is needed, and the energy consumption is consumed to obtain the medium-temperature hot water. At the same time, there is a large amount of low-temperature waste heat (which can be waste heat water, exhaust steam, etc.) in the production process, and some waste heat is discharged due to the inability to be utilized, resulting in waste. In the northern winter heating area, in order to save energy and reduce emissions, the first type lithium bromide absorption heat pump technology is used to recover and utilize the low-temperature waste heat under the condition of high-temperature heat source driving to produce the required medium-temperature hot water, which can save 40% of energy consumption and realize the comprehensive utilization of energy. However, in the case of low-temperature waste heat and high-temperature heat source shortage or no high-temperature heat source, the first type lithium bromide absorption heat pump unit as shown in Figure 1 is used to recover and utilize the low-temperature waste heat to produce the medium-temperature hot water, which needs to increase the equipment and system investment to obtain the high-temperature heat source. In addition, in the production process, when there is a medium-temperature heat source and a higher temperature heat source is needed, in order to save energy, the ordinary two-stage type second lithium bromide absorption heat pump unit as shown in Figure 2 is used to deeply recover and utilize the medium-temperature waste heat to produce a higher temperature heat source. However, the unit does not need high-temperature heat source driving, but has a requirement for the quality of the waste heat, and the waste heat temperature generally needs to be above 55°C to be recovered and utilized. For the low-temperature waste heat below 55°C, it is difficult to recover and utilize. In order to save energy and reduce investment, and to deeply recover and utilize the low-temperature waste heat (waste heat water below 55°C, exhaust steam (pressure below 16 kPa.A) and the like), how to realize the low-temperature waste heat source driving without high-temperature heat source driving, deeply recover and utilize the low-temperature waste heat, and produce a higher temperature medium-temperature hot water with a larger temperature rise than the waste heat for the heat pump unit used for winter central heating or production process preheating, freezing prevention and the like, has become one of the important research topics. SUMMARY

[0003] The present application aims to overcome the above-mentioned deficiencies, and provide a low-temperature waste heat driven large temperature rise two-stage type lithium bromide absorption heat pump unit for deeply recovering low-temperature waste heat to produce a higher temperature medium-temperature hot water with a larger temperature rise than the waste heat for winter central heating or production process preheating, freezing prevention and the like.

[0004] The purpose of the present application is achieved as follows:

[0005] The application discloses a low-temperature waste heat driven large-temperature-rise two-stage type second lithium bromide absorption heat pump unit, which comprises a primary generator, a secondary generator, a condenser, an evaporator, a primary absorber, a secondary absorber, a heat exchanger, a shielding pump, connecting pipelines and a control system, and the evaporator is composed of an evaporator heat transfer pipe, an evaporator front end chamber, an evaporator rear end chamber, a waste steam condensate outlet pipeline, a waste steam condensate pump and a vacuumizing pipeline.

[0006] The low-temperature waste heat source is sequentially introduced into the primary generator heat transfer pipe for temperature reduction, then into the secondary generator heat transfer pipe for temperature reduction, and finally flows out from the low-temperature waste heat water outlet pipeline.

[0007] The low-temperature cooling water is sequentially introduced into the condenser heat transfer pipe for heat absorption and temperature rise, provides low-temperature and low-pressure conditions for the concentrated solution of the secondary generator, then the low-temperature cooling water is introduced into the primary absorber for heat absorption and temperature rise, provides low-temperature and low-pressure conditions for the concentrated solution of the primary generator, and finally flows out from the low-temperature cooling water outlet pipeline.

[0008] Preferably, the medium-temperature hot water is introduced into the absorber heat transfer pipe for heat absorption through a medium-temperature hot water inlet pipeline, and the hot water flows out from a medium-temperature hot water outlet pipeline after temperature rise, and the heat carried out by the medium-temperature hot water can be used for winter central heating, cold source preheating in a production process or a place requiring anti-freezing.

[0009] Preferably, a condenser is arranged on the medium-temperature hot water inlet pipeline, a low-pressure waste steam inlet pipeline is led out from the low-pressure waste steam inlet pipeline and connected with the condenser, the waste steam condensate water from the condenser is connected with the waste steam condensate outlet pipeline at the lower part of the evaporator rear end chamber through a condenser waste steam condensate pipeline, the waste steam condensate water from the evaporator and the condenser is pumped out by the waste steam condensate pump, and the vacuumizing pipeline of the condenser is connected with the vacuumizing pipeline of the evaporator rear end chamber.

[0010] The application has the following beneficial effects:

[0011] The present application provides low-temperature cooling water to the condenser and the first absorber under the premise of ensuring the safety of the cooling tower, reduces the condensing temperature, reduces the secondary generation pressure, and also makes the first absorption pressure and the first generation pressure lower, the solution concentration between the first absorption and the secondary generation lower, the saturation temperature of the solution lower, and the temperature requirement of the low-temperature waste heat source into the secondary generator lower. When the first generation pressure is reduced, the saturation temperature of the dilute solution and the concentrated solution in the first generator is reduced, and the temperature requirement of the low-temperature waste heat source into the first generator is also low when the concentration of the circulating dilute solution and concentrated solution between the secondary absorber and the first generator for preparing medium-temperature hot water with a higher temperature is certain. Therefore, the low-temperature waste heat source is deeply recycled and utilized while driving the unit. The peripheral vacuum system can extract the evaporator tube into a vacuum through the vacuum pipeline, ensure that the low-pressure exhaust steam can enter the evaporator heat transfer tube to condense, and the exhaust steam has no temperature drop except pressure loss, the evaporation temperature is relatively high, the secondary absorption pressure is high, the saturation temperature of the dilute solution and the concentrated solution is increased when the concentration of the dilute solution and the concentrated solution in the secondary absorber is certain, and the secondary absorber can prepare medium-temperature hot water with a higher temperature. The unit can be operated in a wider range of operating conditions because the low-pressure exhaust steam with a slightly higher temperature enters the evaporator, and the waste heat source with a slightly lower temperature enters the first generator and the secondary generator, which improves the adaptability and safety. When a heat pump with a pre-condenser is used, the proportion of the heat of the prepared medium-temperature hot water is increased. It can be seen that the unit does not consume high-temperature energy, but only needs to be driven by a low-temperature waste heat source, deeply recycles and utilizes the waste heat of the low-temperature waste heat source (waste heat water below 55°C and exhaust steam below 16 kPa.A), prepares medium-temperature hot water with a higher outlet temperature, and supplies winter central heating or cold source preheating for production processes or for places requiring frost prevention, 100% energy-saving energy consumption, reduces waste heat emission, and realizes green and environmentally friendly economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A flow process schematic diagram of a first type of lithium bromide absorption heat pump unit in the prior art.

[0013] Figure 2 A flow process schematic diagram of a common two-stage second type of lithium bromide absorption heat pump unit in the prior art.

[0014] Figure 3 A flow process schematic diagram of a low-temperature waste heat driven large temperature rise two-stage second type of lithium bromide absorption heat pump unit of the present application.

[0015] Figure 4 A flow process schematic diagram of a low-temperature waste heat driven large temperature rise two-stage second type of lithium bromide absorption heat pump unit with a condenser of the present application.

[0016] The system includes: Generator 1, Condenser 2, Evaporator 3, Absorber 4, Heat Exchanger 5, Refrigerant Pump 6, Solution Pump 7, High-Temperature Heat Source Inlet Pipeline 8, High-Temperature Heat Source Outlet Pipeline 9, Medium-Temperature Hot Water Outlet Pipeline 10, Low-Temperature Waste Hot Water Outlet Pipeline 11, Low-Temperature Waste Hot Water Inlet Pipeline 12, Medium-Temperature Hot Water Inlet Pipeline 13, Secondary Absorber 14, Cooling Water Outlet Pipeline 15, Cooling Water Inlet Pipeline 16, Secondary Generator 17, Primary Generator 18, Condenser Refrigerant Water Pump 19, Secondary Generator Solution Pump 20. First-stage generator solution pump; 21. First-stage absorber solution pump; 22. Low-temperature heat exchanger; 23. First-stage absorber; 24. High-temperature heat exchanger; 25. Low-pressure exhaust steam inlet pipe; 26. Evaporator front chamber; 27. Evaporator heat transfer tube; 28. Evaporator rear chamber; 29. ​​Vacuum pumping pipe; 30. Exhaust steam condensate outlet pipe; 31. Exhaust steam condensate pump; 32. Low-pressure exhaust steam inlet condenser pipe; 33. Condenser vacuum pumping pipe; 34. Condenser exhaust steam condensate outlet pipe; 35. Condenser; 36. Detailed Implementation

[0017] Example 1:

[0018] See Figure 3 This invention relates to a low-temperature waste heat driven, high-temperature-rise two-stage type II lithium bromide absorption heat pump unit, comprising a primary generator 18, a secondary generator 17, a condenser 2, an evaporator 3, a primary absorber 24, a secondary absorber 14, a high-temperature heat exchanger 25, a shielded pump, connecting pipes, and a control system (not shown in the figure). The evaporator 3 consists of evaporator heat transfer tubes 28, an evaporator front chamber 27, an evaporator rear chamber 29, a vacuum line 30, a waste steam condensate outlet line 31, and a waste steam condensate pump 32. Low-pressure waste steam enters the evaporator front chamber 27 through the low-pressure waste steam inlet line 26 and then enters the evaporator heat transfer tubes 28 for condensation. Waste steam condensate is extracted by the waste steam condensate pump located on the waste steam condensate outlet line 31 at the bottom of the evaporator rear chamber 29. Furthermore, a vacuum line 30 is provided in the vapor phase zone at the top of the evaporator rear chamber 29, and the vacuum line 30 is connected to the external... The system is connected to a water-ring vacuum pump or an existing vacuum system. Low-temperature waste heat source enters the heat transfer tubes of the first-stage generator 18 via the low-temperature waste water inlet pipe 12 for cooling, then enters the heat transfer tubes of the second-stage generator 17 for further cooling, and finally flows out from the low-temperature waste water outlet pipe 11. Low-temperature cooling water enters the heat transfer tubes of the condenser 2 via the cooling water inlet pipe 16 for heat absorption and temperature rise, providing low-temperature and low-pressure conditions for the concentrated solution in the second-stage generator 17. Then, the low-temperature cooling water enters the first-stage absorber 24 for heat absorption and temperature rise, providing low-temperature and low-pressure conditions for the concentrated solution in the first-stage generator 18, and finally flows out from the cooling water outlet pipe 15. Medium-temperature hot water enters the heat transfer tubes of the second-stage absorber 14 via the medium-temperature hot water inlet pipe 13 for heat absorption and temperature rise, and then flows out from the medium-temperature hot water outlet pipe 10. The heat carried by the medium-temperature hot water can be used for centralized heating in winter, preheating of cold sources in production processes, or for locations requiring antifreeze, etc.

[0019] The unit has one low-temperature, low-concentration solution cycle, one high-temperature, high-concentration solution cycle, and one refrigerant cycle. The low-temperature, low-concentration solution cycle process is as follows: the primary absorber solution pump 22 pumps the dilute solution in the liquid bladder directly into the spray pipe of the secondary generator 17 through pipelines. The secondary generator 17 concentrates the dilute solution sprayed onto the heat transfer tube surface into a concentrated solution. The concentrated solution enters the liquid bladder at the bottom of the secondary generator 17 cylinder, where the secondary generator solution pump 20 pumps the concentrated solution directly into the spray pipe of the primary absorber 24 through pipelines. On the surface of the heat transfer tubes, the concentrated solution absorbs the refrigerant vapor generated by the primary generator 18, becoming a dilute solution before entering the liquid bladder. Since the temperature difference between the dilute and concentrated solutions in this cycle is small, a low-temperature solution heat exchanger is not required for heat recovery. Another high-temperature, high-concentration solution circulation process is as follows: the primary generator 18 concentrates the dilute solution sprayed onto the heat transfer tube surface into a concentrated solution. The concentrated solution enters the liquid bladder at the bottom of the primary generator cylinder, is pumped by the primary generator solution pump 21, heated by the high-temperature heat exchanger 25, and then enters the secondary absorber 14, where it is sprayed onto the heat transfer tubes. On the surface of the heat pipe, the concentrated solution absorbs the high-temperature refrigerant vapor evaporated from the evaporator 3 and becomes a dilute solution. The dilute solution collects in the liquid sac at the bottom of the secondary absorber cylinder. Driven by pressure and potential differences, it is cooled by the high-temperature heat exchanger 25 and then sprayed through the spray pipes of the primary generator 18. One refrigerant cycle is as follows: the refrigerant vapor generated by the concentration of the dilute solution from the secondary absorber 14 in the primary generator 18 enters the primary absorber 24 through the baffle plate assembly. The refrigerant vapor is absorbed by the concentrated solution sprayed on the surface of the heat transfer tubes of the primary absorber 24 and becomes a dilute solution. This dilute solution then enters the primary absorber 24. The secondary generator 17 concentrates the refrigerant into a concentrated solution. The refrigerant vapor generated during concentration enters the condenser 2 via a baffle plate assembly. This refrigerant vapor condenses into low-temperature refrigerant water on the surface of the heat transfer tubes in the condenser 2. This low-temperature refrigerant water is pumped into the liquid sac of the evaporator 3 by the condenser refrigerant water pump 19. The refrigerant circulating water is then pumped into the spray pipes of the evaporator 3 and sprayed onto the surface of the heat transfer tubes. The refrigerant water absorbs heat and evaporates into high-temperature refrigerant vapor, which then enters the secondary absorber 14. This high-temperature refrigerant vapor is absorbed by the concentrated solution sprayed onto the surface of the heat transfer tubes in the secondary absorber 14, becoming a dilute solution. This cycle continues continuously.

[0020] Example 2:

[0021] like Figure 4As shown, when the temperature of the medium-temperature hot water entering the heat pump is lower than the temperature of the low-pressure exhaust steam, based on Example 1, a condenser 36 is installed on the medium-temperature hot water inlet pipe 13. A low-pressure exhaust steam inlet pipe 33 is led out from the low-pressure exhaust steam inlet pipe 26 and connected to the condenser 36. The exhaust steam condensate exiting the condenser is connected to the exhaust steam condensate outlet pipe 31 at the bottom of the evaporator rear end chamber 29 through the condenser exhaust steam condensate pipe 35. The exhaust steam condensate condensed in the evaporator 3 and the condenser 36 are combined and then extracted together by the exhaust steam condensate pump 32. The condenser vacuum pipe 34 is connected to the vacuum pipe 30 on the evaporator rear end chamber 29. The medium-temperature hot water first enters the condenser 36 to exchange heat with the low-pressure exhaust steam. After the medium-temperature hot water is preheated, it enters the secondary absorber 14 to be heated.

[0022] This invention, through the aforementioned innovations, utilizes the low winter temperatures. After cooling water reaches the cooling tower, it is regulated by a fan to provide low-temperature cooling water (e.g., inlet / outlet temperatures of 5℃ / 10℃, 10℃ / 15℃, or 15℃ / 20℃, etc., the low-temperature circulating water temperature determined as needed) to the condenser 2 and the primary absorber 24, thereby lowering the condensation temperature, reducing the secondary generator pressure, and further lowering the primary absorber and generator pressures. This results in lower solution concentration and saturation temperature in the circulation between the primary absorber and secondary generator, and a lower temperature requirement for the low-temperature waste heat source entering the secondary generator. Because the primary generator pressure is lowered, the secondary absorber 1, which is required to produce higher-temperature medium-temperature hot water, is also lower. When the concentrations of the dilute and concentrated solutions circulating between generator 4 and the first-stage generator 18 are constant, the saturation temperature of the dilute and concentrated solutions in the first-stage generator 18 decreases, and the temperature requirement of the low-temperature waste heat source entering the first-stage generator 18 is also lower. Therefore, while driving the unit, the waste heat of the low-temperature waste heat source is deeply recovered and utilized. The external vacuum system can evacuate the tube side of evaporator 3 to a vacuum through vacuum pipe 30, ensuring that low-pressure exhaust steam can enter the heat transfer tubes of evaporator 3 for condensation. Except for pressure loss, there is no temperature drop in the exhaust steam, and the evaporation temperature is relatively high, resulting in a higher pressure in the second-stage absorption. When the concentrations of the dilute and concentrated solutions in the second-stage absorber 14 are constant, the saturation temperature of the dilute and concentrated solutions increases, and the second-stage absorber 14 can produce medium-temperature hot water at a higher temperature. Introducing slightly higher-grade low-pressure exhaust steam into the evaporator and slightly lower-grade waste heat source into the first-stage and second-stage generators increases the range of variable operating conditions of the unit, making it more adaptable and improving safety. When a heat pump with a pre-condenser is used, the heat ratio of the produced medium-temperature hot water increases. It is evident that this unit does not require high-temperature energy consumption; it is driven solely by low-temperature waste heat sources. Under the condition of providing low-temperature cooling water, it deeply recovers and utilizes the waste heat from low-temperature waste heat sources (waste hot water below 55℃ and exhaust steam below 16kPa.A, etc.) to produce medium-temperature hot water with a higher outlet temperature (around 70℃~95℃) than the low-temperature waste heat. This hot water is used for centralized heating in winter, preheating of cold sources in production processes, or for use in places requiring antifreeze. It achieves 100% energy saving, reduces waste heat emissions, and realizes green and environmentally friendly economic and social benefits.

[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 low-temperature waste heat driven, high-temperature-rise two-stage type second-class lithium bromide absorption heat pump unit, comprising a primary generator (18), a secondary generator (17), a condenser (2), an evaporator (3), a primary absorber (24), a secondary absorber (14), a high-temperature heat exchanger (25), a shielded pump, connecting pipelines, and a control system, wherein the evaporator (3) is composed of an evaporator heat transfer tube (28), an evaporator front end chamber (27), an evaporator rear end chamber (29), a vacuum pipeline (30), a waste steam condensate outlet pipeline (31), and a waste steam condensate pump (32), characterized in that: Low-pressure exhaust steam enters the front chamber (27) of the evaporator through the low-pressure exhaust steam inlet pipe (26) and then enters the heat transfer tube (28) of the evaporator for condensation. The exhaust steam condensate is pumped out by the exhaust steam condensate pump on the exhaust steam condensate outlet pipe (31) located at the bottom of the rear chamber (29) of the evaporator. In addition, a vacuum pumping pipe (30) is provided in the vapor phase zone at the top of the rear chamber (29) of the evaporator. The vacuum pumping pipe (30) is connected to the water ring vacuum pump or the existing vacuum pumping system located on the periphery. The low-temperature waste heat source enters the heat transfer tube of the first-stage generator (18) in series through the low-temperature waste water inlet pipe (12) for cooling, then enters the heat transfer tube of the second-stage generator (17) for cooling, and finally flows out from the low-temperature waste water outlet pipe (11). Low-temperature cooling water enters the heat transfer tube of condenser (2) in series through cooling water inlet pipe (16) to absorb heat and increase temperature, providing low-temperature and low-pressure conditions for the concentrated solution of secondary generator (17). Then, the low-temperature cooling water enters the primary absorber (24) to increase temperature and absorb heat, providing low-temperature and low-pressure conditions for the concentrated solution of primary generator (18). Finally, it flows out from cooling water outlet pipe (15). The primary absorber (24), the primary absorber solution pump (22), the secondary generator (17), and the secondary generator solution pump (20) form a low-temperature, low-concentration solution circulation for the unit; Low-temperature cooling water is used for the condenser (2) and the primary absorber (24), which lowers the condensation temperature, reduces the secondary generator pressure, and also lowers the primary absorber pressure and the primary generator pressure. The solution concentration circulating between the primary absorber and the secondary generator is lower, the saturation temperature of the solution is lower, and the temperature requirement of the low-temperature waste heat source entering the secondary generator is lower. Because the primary generator pressure is lower, when the concentration of the dilute and concentrated solutions circulating between the secondary absorber (14) and the primary generator (18) required to produce medium-temperature hot water at a higher temperature is constant, the saturation temperature of the dilute and concentrated solutions in the primary generator (18) is lower, and the temperature requirement of the low-temperature waste heat source entering the primary generator (18) is also lower. While driving the unit, the waste heat of the low-temperature waste heat source is deeply recovered and utilized.

2. The low-temperature waste heat driven, high-temperature-rise two-stage second-type lithium bromide absorption heat pump unit according to claim 1, characterized in that: Medium-temperature hot water enters the heat transfer tube of the secondary absorber (14) through the medium-temperature hot water inlet pipe (13) to absorb heat, and after being heated, it flows out from the medium-temperature hot water outlet pipe (10).

3. A low-temperature waste heat driven, high-temperature-rise two-stage second-type lithium bromide absorption heat pump unit according to claim 1 or 2, characterized in that: A condenser (36) is installed on the medium-temperature hot water inlet pipe (13). A low-pressure waste steam inlet pipe (33) is led out from the low-pressure waste steam inlet pipe (26) and connected to the condenser (36). The waste steam condensate exiting the condenser is connected to the waste steam condensate outlet pipe (31) at the bottom of the evaporator rear end chamber (29) through the condenser waste steam condensate pipe (35). The waste steam condensate condensed in the evaporator (3) and the condenser (36) are combined and then pumped out together by the waste steam condensate pump (32). The condenser vacuum pipe (34) is connected to the vacuum pipe (30) on the evaporator rear end chamber (29). The medium-temperature hot water first enters the condenser (36) to exchange heat with the low-pressure waste steam. After the medium-temperature hot water is preheated, it enters the secondary absorber (14) to be heated.

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