A large-temperature-difference absorption heat exchange equipment applied to a long-distance heat supply system

Abstract

The utility model discloses a kind of large temperature difference absorption type heat exchange equipment applied to long heat supply system, including generator, condenser, solution exchanger, absorber and evaporator, primary network water supply pipeline is sequentially connected in the heat source side of generator and evaporator, secondary network backwater pipeline is sequentially connected in the heated side of absorber and condenser, solution exchanger, generator, absorber, condenser and evaporator form working medium circulation unit, for absorbing the heat of primary water to heat secondary water;The heat source side of generator primary water outlet end is also connected with temperature-driven heat exchanger, the inlet end of temperature-driven heat exchanger heated side is connected on secondary water pipeline, for introducing secondary network backwater in severe cold period, the outlet end of temperature-driven heat exchanger heated side is connected with the outlet end of condenser heated side, and heat user is connected by secondary network water supply pipeline.

Description

Technical Field

[0001] This utility model relates to the field of heating equipment technology, and more specifically to a large temperature difference absorption heat exchanger applied to long-distance heating systems. Background Technology

[0002] In recent years, with the continuous increase in newly constructed buildings in my country, the area requiring connection to urban centralized heating pipe networks has also expanded. In long-distance heating systems, reducing the return water temperature and increasing the temperature difference between the supply and return water are key to improving the network's transmission capacity and reducing the energy consumption of circulating water pumps. Large temperature difference heating can effectively reduce network transmission energy consumption and increase the heating radius. Traditional heat exchange stations use plate heat exchangers for indirect heat exchange. Due to the thermodynamic balance limitation of the primary network return water temperature, it can usually only approach the secondary network return water temperature, making it difficult to further expand the system's transmission temperature difference (generally not exceeding 60℃), thus limiting its energy-saving potential.

[0003] Absorption heat pump technology utilizes a high-temperature heat source to "pump" heat from a low-temperature heat source to a higher temperature for utilization. However, while there are existing cases of using absorption heat pumps for heating, their system coupling methods are usually relatively simple, failing to fully utilize the cooling potential of the primary water network. Furthermore, lithium bromide absorption systems suffer from limited temperature differences and insufficient heating capacity during severe cold periods. Therefore, a system capable of providing heating with large temperature differences and adapting to severe cold conditions is needed. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a large temperature difference absorption heat exchanger for long-distance heating systems, which is suitable for efficient operation during severe cold periods. Through innovative system coupling and process design, the cooling potential of the primary network return water is deeply explored to achieve an unconventional transmission temperature difference.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows.

[0006] A large temperature difference absorption heat exchanger for long-distance heating systems includes a generator, a condenser, a solution exchanger, an absorber, and an evaporator. A primary network water supply pipeline is sequentially connected to the heat source side of the generator and evaporator, while a secondary network return water pipeline is sequentially connected to the heated side of the absorber and condenser. The solution exchanger, generator, absorber, condenser, and evaporator form a working fluid circulation unit for absorbing heat from the primary water to heat the secondary water. The primary water outlet of the generator's heat source side is also connected to a temperature-driven heat exchanger for absorbing heat from the primary water outlet during periods of severe cold to heat the secondary network return water. The inlet of the temperature-driven heat exchanger on the heated side is connected to the secondary water pipeline for introducing secondary network return water during periods of severe cold. The outlet of the temperature-driven heat exchanger on the heated side is connected to the outlet of the condenser on the heated side, and the system is connected to heat users via the secondary network water supply pipeline.

[0007] To further optimize the technical solution, the tube side of the generator and evaporator is connected to the primary network water supply pipeline, the shell side of the generator and evaporator is connected to the working fluid circulation unit, the tube side of the absorber and condenser is connected to the secondary network return water pipeline, and the shell side of the absorber and condenser is connected to the working fluid circulation unit.

[0008] The technical solution is further optimized. The working fluid circulation unit includes a lithium bromide solution circulation pipeline consisting of the shell side of the solution exchanger, generator, and absorber, and a water vapor circulation pipeline consisting of the shell side of the generator, condenser, evaporator, and absorber.

[0009] To further optimize the technical solution, a throttling valve is installed between the shell side of the condenser and the evaporator to reduce the pressure of liquid water in the water vapor circulation pipeline.

[0010] To further optimize the technical solution, the primary water at the heat source side outlet of the temperature-driven heat exchanger and the primary water at the heat source side outlet of the evaporator are combined and then connected to the primary network return water pipeline.

[0011] The technical solution is further optimized. The solution exchanger includes a cylinder that is horizontally set on the ground by support legs. The inside of the cylinder is provided with a flow channel for dilute solution to flow. The flow channel is provided with a spiral concentrated solution flow pipe for concentrated solution to flow. The left and right sides of the cylinder are provided with a concentrated solution inlet pipe and a concentrated solution outlet pipe that connect to the concentrated solution flow pipe, as well as a dilute solution inlet pipe and a dilute solution outlet pipe that connect to the flow channel inside the cylinder.

[0012] To further optimize the technical solution, the flow channel of the cylinder is provided with several baffles for interfering with the dilute solution, and the baffles are provided with several flow holes for the dilute solution to flow through.

[0013] To further optimize the technical solution, the concentrated solution inlet pipe and the dilute solution inlet pipe are respectively equipped with a concentrated solution pump and a dilute solution pump for feeding the concentrated solution and the dilute solution into the cylinder.

[0014] To further optimize the technical solution, a pressure gauge for detecting the air pressure inside the cylinder and an exhaust pipe for discharging excess gas are installed above the cylinder body, and an exhaust valve for controlling the exhaust is installed inside the exhaust pipe.

[0015] The technological advancements achieved by this utility model are as follows, due to the adoption of the above technical solutions.

[0016] This utility model provides a large temperature difference absorption heat exchanger for long-distance heating systems. Through the design of "two cooling cycles for primary water, two heating cycles for secondary water + supplementary heating during severe cold periods by a temperature-driven heat exchanger", it achieves large temperature difference heating and improves the system's heating capacity during severe cold periods. At the same time, it recovers the heat of lithium bromide solution through a solution heat exchanger, improving energy utilization efficiency. It is suitable for urban centralized heating scenarios with large temperature differences. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of the present invention. Figure 2 This is a schematic diagram of the solution exchanger of this utility model; Figure 3 This is a schematic diagram of the internal structure of the solution exchanger of this utility model.

[0018] Among them: 1. Generator, 2. Condenser, 3. Solution exchanger, 4. Absorber, 5. Evaporator, 6. Temperature-driven heat exchanger, 7. Heat user, 8. Throttling valve; 31. Cylinder body; 32. Support leg; 33. Concentrated solution inlet pipe; 34. Concentrated solution outlet pipe; 35. Concentrated solution pump; 36. Dilute solution inlet pipe; 37. Dilute solution outlet pipe; 38. Dilute solution pump; 39. Pressure gauge; 310. Exhaust pipe; 311. Concentrated solution flow pipe; 312. Baffle plate; 313. Flow hole. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] A large temperature difference absorption heat exchanger for long-distance heating systems, combined with Figure 1 As shown, the system includes a generator 1, a condenser 2, a solution exchanger 3, an absorber 4, an evaporator 5, and a temperature-driven heat exchanger 6. The primary water supply pipeline is connected in sequence to the heat source side of the generator 1 and the evaporator 5 to realize the primary water circulation pipeline. The secondary water return pipeline is connected in sequence to the heated side of the absorber 4 and the condenser 2 to realize the secondary water circulation pipeline. The solution exchanger 3, the generator 1, the absorber 4, the condenser 2, and the evaporator 5 form a working fluid circulation unit, which is used to absorb the heat of the primary water to heat the secondary water.

[0021] A heat exchanger 6 is also connected to the primary water outlet on the heat source side of generator 1. The inlet end of the heat exchanger 6 on the heated side is connected to the secondary water pipeline, introducing secondary water into the heat exchanger 6. During severe cold periods, the heat exchanger absorbs heat from the primary water outlet to heat the secondary network return water. The outlet end of the heat exchanger 6 on the heated side is connected to the outlet end of the condenser 2 on the heated side, and is connected to the heat user 7 through the secondary network supply water pipeline. The primary water at the heat source side outlet end of the heat exchanger 6 mixes with the primary water at the heat source side outlet end of the evaporator 5 and is then connected to the primary network return water pipeline.

[0022] The tube side of generator 1 and evaporator 5 is connected to the primary network water supply pipeline, and the shell side of generator 1 and evaporator 5 is connected to the working fluid circulation unit. The tube side of absorber 4 and condenser 2 is connected to the secondary network return water pipeline, and the shell side of absorber 4 and condenser 2 is connected to the working fluid circulation unit.

[0023] The working fluid circulation unit includes a lithium bromide solution circulation pipeline and a steam circulation pipeline. The lithium bromide solution circulation pipeline consists of the shell side of the solution exchanger 3 and the generator 1 and absorber 4. The steam circulation pipeline consists of the shell side of the generator 1, condenser 2, evaporator 5 and absorber 4. A throttling valve 8 is installed between the shell side of the condenser 2 and the evaporator 5 to reduce the pressure of the liquid water in the steam circulation pipeline.

[0024] The structure of solution exchanger 3 is as follows Figures 2 to 3 As shown, the solution exchanger 3 includes a cylindrical body 31 horizontally mounted on the ground via support legs 32. The interior of the cylindrical body 31 is provided with a flow channel for the flow of dilute solution. The flow channel is also provided with a spiral flow channel for the flow of concentrated solution. On the left and right sides of the cylindrical body 31, there are intersecting concentrated solution inlet pipes 33 and 34, concentrated solution outlet pipes 34, dilute solution inlet pipes 36 and 37. The concentrated solution inlet pipes 33 and 34 are connected to both ends of the concentrated solution flow channel 311, and the dilute solution inlet pipes 36 and 37 are connected to the flow channel, thereby realizing the flow and heat exchange of concentrated and dilute solutions.

[0025] The cylinder 31 has several vertical baffles 312 in its flow channel, and several flow holes 313 are provided on the baffles 312 for the flow of dilute solution. The baffles interfere with the dilute solution, prolonging the heat exchange time between the dilute solution and the concentrated solution and improving the heat exchange efficiency between the concentrated solution and the dilute solution.

[0026] Concentrated solution inlet pipe 33 and dilute solution inlet pipe 36 are respectively equipped with concentrated solution pump 35 and dilute solution pump 38, which are used to send concentrated solution and dilute solution into the cylinder for heat exchange.

[0027] A pressure gauge 39 and an exhaust pipe 310 are installed above the cylinder 31. The pressure gauge is used to detect the pressure inside the cylinder, and the exhaust pipe 310 is used to discharge excess gas. An exhaust valve is installed inside the exhaust pipe to control the exhaust. The concentrated solution from the generator enters the spiral pipe inside the cylinder through the concentrated solution inlet pipe, and the dilute solution from the absorber enters the flow channel inside the cylinder through the dilute solution inlet pipe. The dilute and concentrated solutions exchange heat. The concentrated solution enters the absorber behind it through the concentrated solution outlet pipe, and the dilute solution flows out through the dilute solution outlet pipe and enters the generator to exchange heat again.

[0028] The circulation path of the primary water under normal operating conditions is as follows: the high-temperature hot water from the primary network first enters the tube side of the generator, where it serves as a driving heat source and exchanges heat with the low-concentration lithium bromide dilute solution in the shell side. After flowing out of the generator and undergoing the first cooling process, the primary water enters the tube side of the evaporator and exchanges heat with the low-pressure evaporating refrigerant in the shell side of the evaporator. The primary water further releases heat, completing the cooling under normal operating conditions.

[0029] The circulation path of the primary water during severe cold periods is as follows: If it is a severe cold period, the secondary water requires more heat. After the primary water is cooled down for the first time by the generator, it flows into the temperature-driven heat exchanger and directly exchanges heat with the secondary water to supplement the heating of the secondary water. Finally, the temperature of the primary network water flowing out from the temperature-driven heat exchanger and evaporator has dropped to an extremely low level and flows into the primary network return water to return to the heat source end.

[0030] The circulation path of the secondary side water under normal operating conditions is as follows: The secondary side return water first enters the tube side of the absorber, where it absorbs the heat released when the lithium bromide solution and refrigerant vapor are mixed and diluted in the shell side, and then flows out of the absorber. The secondary water, heated by the absorber, enters the tube side of the condenser, where it absorbs the heat released when the refrigerant vapor in the shell side is condensed and liquefied, further increasing its temperature. It then serves as the heating medium to provide heat to users, completing the heating under normal operating conditions.

[0031] The circulation path of secondary side water during severe cold periods is as follows: During severe cold periods, some of the secondary return water directly enters the temperature drive heat exchanger, where it exchanges heat with the primary water flowing out of the generator after the first cooling. After absorbing heat, it mixes with the secondary water flowing out of the condenser and is then jointly delivered to the heat users.

[0032] The lithium bromide solution cycle achieves heat absorption and release through a "dilute solution-concentrated solution-dilute solution" loop, circulating from the generator to the solution exchanger, absorber, solution exchanger, and back to the generator. The specific path is as follows: Generator: A low-concentration lithium bromide dilute solution (state e) enters the generator shell side, absorbs the heat released by the first cooling of the primary side water, the water in the solution is evaporated and precipitated, the concentration of the remaining solution increases, becoming a high-concentration lithium bromide concentrated solution (state d), and superheated steam (state d') is generated and enters the condenser.

[0033] Solution exchanger: The high-temperature concentrated solution (state d) flowing out of the generator enters one side of the solution exchanger and exchanges heat with the low-temperature dilute solution (state b) from the absorber on the other side. After the concentrated solution releases heat, its temperature decreases (state f) and it enters the absorber.

[0034] Absorber: The cooled concentrated solution (state f) enters the shell side of the absorber and mixes with the refrigerant saturated water vapor (state a') flowing in from the evaporator. The concentrated solution absorbs the water vapor and is diluted into a low-concentration dilute solution (state b). At the same time, it releases a large amount of dilution heat, which is absorbed by the secondary return water in the tube side of the absorber, completing the first heating of the secondary water.

[0035] Solution exchanger: The low-temperature dilute solution (state b) flowing out of the absorber enters the other side of the solution exchanger, absorbs the heat released by the concentrated solution (state d), and its temperature rises (state e). It then re-enters the generator to complete the circulation of the lithium bromide solution.

[0036] In the water vapor circulation pipeline, water is used as the refrigerant. Through a phase change cycle of "water vapor - liquid water - water vapor," heat is transferred from the primary side to the secondary side. The circulation occurs from generator to condenser, condenser to evaporator, and evaporator to absorber. The specific path is as follows: Generator-Condenser: The superheated steam (state d') generated by evaporation in the generator enters the shell side of the condenser and exchanges heat with the secondary water in the tube side. The steam condenses into saturated liquid water (state c). The heat of condensation is absorbed by the secondary water, completing the second heating of the secondary water.

[0037] Condenser-Evaporator: The saturated liquid water (state c) flowing out of the condenser is depressurized by the throttling valve and becomes low-temperature, low-pressure liquid water (state a) which enters the shell side of the evaporator and exchanges heat with the primary water in the tube side. The liquid water absorbs the heat from the primary water and evaporates into saturated water vapor (state a'), which cools the primary water a second time.

[0038] Evaporator-Absorber: Saturated water vapor (state a') generated by the evaporator enters the shell side of the absorber and is absorbed by the concentrated lithium bromide solution (state f), completing the refrigerant cycle.

[0039] In this invention, during the heating season, the high-temperature water supply from the primary network flows into the tube side of the generator, heats the dilute lithium bromide solution, and then flows out after the first cooling. After flowing out, it splits into two paths: one part enters the tube side of the evaporator to further release heat and cool down; the other part enters the side of the temperature-driven heat exchanger during the severe cold period to heat part of the secondary network water. After cooling down, it mixes with the water coming out of the evaporator and returns to the heat source through the primary network return water pipe.

[0040] Part of the secondary network return water enters the tube side of the absorber and the tube side of the condenser for heating, while the other part enters the temperature drive heat exchanger for heating during severe cold periods. The heated water from the two sources is mixed and then enters the heat users through the secondary network water supply pipeline to provide heating to them.

Claims

1. A large temperature difference absorption heat exchanger for use in long-distance heating systems, characterized in that: The system includes a generator (1), a condenser (2), a solution exchanger (3), an absorber (4), and an evaporator (5). The primary network water supply pipeline is connected in sequence to the heat source side of the generator (1) and the evaporator (5). The secondary network return water pipeline is connected in sequence to the heated side of the absorber (4) and the condenser (2). The solution exchanger (3), generator (1), absorber (4), condenser (2), and evaporator (5) form a working fluid circulation unit, which is used to absorb the heat of the primary water to heat the secondary water. The primary water outlet end of the heat source side of the generator (1) is also connected to a temperature-driven heat exchanger (6), which is used to absorb the heat of the primary water outlet to heat the secondary network return water during the cold season. The inlet end of the temperature-driven heat exchanger (6) on the heated side is connected to the secondary water pipeline, which is used to introduce the secondary network return water during the cold season. The outlet end of the temperature-driven heat exchanger (6) on the heated side is connected to the outlet end of the condenser (2) on the heated side, and is connected to the heat user (7) through the secondary network water supply pipeline.

2. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 1, characterized in that: The tube side of the generator (1) and evaporator (5) is connected to the primary network water supply pipeline, the shell side of the generator (1) and evaporator (5) is connected to the working fluid circulation unit, the tube side of the absorber (4) and condenser (2) is connected to the secondary network return water pipeline, and the shell side of the absorber (4) and condenser (2) is connected to the working fluid circulation unit.

3. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 2, characterized in that: The working fluid circulation unit includes a lithium bromide solution circulation pipeline consisting of the shell side of the solution exchanger (3) and the generator (1) and the absorber (4), and a water vapor circulation pipeline consisting of the shell side of the generator (1), the condenser (2), the evaporator (5) and the absorber (4).

4. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 3, characterized in that: A throttling valve (8) is provided between the shell side of the condenser (2) and the evaporator (5) to reduce the pressure of liquid water in the steam circulation pipeline.

5. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 1, characterized in that: The primary water at the heat source side outlet of the heat-driven heat exchanger (6) and the primary water at the heat source side outlet of the evaporator (5) are combined and then connected to the primary network return water pipeline.

6. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 1, characterized in that: The solution exchanger (3) includes a cylinder (31) horizontally set on the ground by a support leg (32). The cylinder (31) has a flow channel for dilute solution to flow through. The flow channel has a spiral concentrated solution flow pipe (311) for concentrated solution to flow through. The left and right sides of the cylinder (31) are cross-connected with a concentrated solution inlet pipe (33) and a concentrated solution outlet pipe (34) that connect to the concentrated solution flow pipe (311), as well as a dilute solution inlet pipe (36) and a dilute solution outlet pipe (37) that connect to the flow channel inside the cylinder.

7. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 6, characterized in that: The cylinder (31) has several baffles (312) in the flow channel for interfering with the dilute solution, and several flow holes (313) are provided on the baffles (312) for the dilute solution to flow through.

8. The large temperature difference absorption heat exchanger for long-distance heating systems according to claim 6, characterized in that: The concentrated solution inlet pipe (33) and the dilute solution inlet pipe (36) are respectively equipped with a concentrated solution pump (35) and a dilute solution pump (38) for feeding the concentrated solution and the dilute solution into the cylinder.

9. A large temperature difference absorption heat exchanger for long-distance heating systems according to claim 6, characterized in that: A pressure gauge (39) for detecting the air pressure inside the cylinder (31) and an exhaust pipe (310) for discharging excess gas are provided above the cylinder body (31). An exhaust valve for controlling the exhaust is provided inside the exhaust pipe.

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