Pressure isolation station heat supply system and method with flexible temperature difference adjustment

Abstract

The application discloses a pressure-isolating station heat supply system and method capable of flexibly adjusting temperature difference, belongs to the technical field of heat supply, and comprises a plate heat exchanger, an absorption heat pump and a regulating valve group. The plate heat exchanger is connected in series with the absorption heat pump at a primary side, and the plate heat exchanger is connected in parallel with the absorption heat pump at a secondary side heat network return water side. By adjusting the opening degree of the regulating valve group, maximum temperature difference working conditions, adjusted temperature difference working conditions and minimum temperature difference working conditions can be realized, flexible adjustment of the primary side temperature difference is realized, and then flexible adjustment of heat supply load is realized. The system can realize primary network large temperature difference operation and secondary network conventional flow conventional temperature difference operation, does not need to transform other heat exchanger stations at the secondary network end into large temperature difference heat exchanger stations, and has good operability and economy.

Description

Technical Field

[0001] This invention belongs to the field of heating technology, specifically relating to a pressure-reducing station heating system and method with flexibly adjustable temperature difference. Background Technology

[0002] With the acceleration of urbanization and the promotion of centralized heating technology, combined heat and power (CHP) has become the mainstream solution for improving energy efficiency. However, heat sources (such as CHP plants) are usually located on the outskirts of cities, requiring long-distance pipelines to transport heating media to the city center. This leads to pipeline pressure imbalance, which has become a key bottleneck restricting the safe and stable operation of the heating system. On the one hand, long-distance pipelines, due to their long transmission distances and large elevation differences, are generally designed with pressures as high as 2.5 MPa (equivalent to the pressure of a 250m water column), while the design pressure of pipelines in the city center is usually 1.6 MPa. Direct connection can easily lead to overpressure and pipe bursts on the low-pressure side. On the other hand, return water pipelines often experience insufficient pressure due to friction loss, causing system vaporization, venting, and other malfunctions, seriously affecting the continuity of heating. To address this, the industry generally uses pressure isolation stations as the core equipment for pressure isolation and regulation. Through the technical principle of "heat transfer without pressure transfer," the heating system is divided into independent high-pressure primary networks and low-pressure secondary networks, ensuring the coordinated operation of pipelines with different pressure levels. Traditional heating pressure isolation stations mainly adopt a heat exchanger-type structure. The core consists of a plate heat exchanger, a circulating pump, a constant-pressure water supply pump, and auxiliary valves and piping. Its core technology is to achieve intermittent heat exchange between hot and cold media through the plate heat exchanger, while simultaneously isolating the pressure transmission between the primary and secondary networks. Plate heat exchangers, with their high heat transfer coefficient and low pressure drop, have become the mainstream heat exchange equipment. Their working principle involves heat exchange between hot and cold media through the corrugated channels on the heat exchange plates. A single unit is designed to supply water at a temperature of up to 130℃ and return water at approximately 65℃, with a heating capacity covering 1.5-1.8 million square meters of heating demand.

[0003] However, existing traditional heating pressure relief stations have core technological defects that restrict the energy-saving upgrade and cost optimization of heating systems: Traditional pressure relief stations are limited by the inherent heat transfer difference of plate heat exchangers, resulting in a small temperature difference between the primary and secondary networks. This means that under the same heating load demand, the primary network needs to increase the medium flow rate to meet the heat transmission requirements, leading to an oversized design of the primary network pipe diameter. This not only increases the consumption of pipe materials and construction costs but also increases transmission energy consumption due to increased friction resistance. If it is necessary to promote the large temperature difference heat exchange transformation of the centralized heating system (aiming to achieve a primary network supply and return water temperature difference ≥60℃), the secondary network must be matched to the large temperature difference operation conditions. This requires a comprehensive transformation of the existing terminal heat exchange stations, replacing them with dedicated large temperature difference heat exchange units. This transformation involves the dismantling, replacement, and system debugging of a large number of terminal equipment. Not only is the initial investment huge, but the construction must also be completed during the heating season break, with a tight time window and extremely high transformation difficulty. As a result, traditional pressure relief stations are difficult to adapt to the current centralized heating system's large temperature difference energy-saving upgrade requirements.

[0004] Therefore, there is an urgent need for an innovative system integration solution that can overcome the limitations of the aforementioned individual technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of the urgent need to expand heating capacity but the limitation of urban heating networks, and to propose a pressure-reducing station heating system and method that can flexibly adjust the temperature difference.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a pressure-reducing station heating system with flexibly adjustable temperature difference, including a plate heat exchanger, an absorption heat pump and a regulating valve group; the pressure-reducing station heating system is divided into a primary network water circuit and a secondary network water circuit that are independent of each other; In the primary network water circuit, the primary side of the plate heat exchanger is connected in series with the primary side of the absorption heat pump; the primary side input end of the plate heat exchanger is connected to the primary network water supply end; the primary side output end of the plate heat exchanger is connected to the primary side input end of the absorption heat pump; the primary side output end of the absorption heat pump is connected to the primary network water return end; a primary side bypass pipeline is provided between the primary side output end of the plate heat exchanger and the primary side output end of the absorption heat pump. In the secondary network water circuit, the secondary side of the plate heat exchanger and the secondary side of the absorption heat pump are arranged in parallel; the return water end of the secondary network heat network is divided into two paths, the first path is connected to the secondary side input end of the plate heat exchanger, and the second path is connected to the secondary side input end of the absorption heat pump; the secondary side output end of the plate heat exchanger and the secondary side output end of the absorption heat pump are combined and then connected to the secondary network heat network water supply end. The control valve assembly includes a first control valve, a second control valve, a third control valve, and a fourth control valve; The first regulating valve is located at the primary side input end of the absorption heat pump; The fourth regulating valve is installed on the primary bypass pipeline; The second regulating valve is installed at the secondary side inlet of the plate heat exchanger; The third regulating valve is installed at the secondary side input end of the absorption heat pump.

[0007] Furthermore, temperature sensors and flow sensors are installed at the primary input, primary output, secondary input, and secondary output ends of the plate heat exchanger, as well as at the primary input, primary output, secondary input, and secondary output ends of the absorption heat pump.

[0008] Furthermore, the absorption heat pump is a lithium bromide absorption heat pump.

[0009] Furthermore, the absorption heat pump is connected to a drive heat source input pipeline.

[0010] Furthermore, the supply medium for driving the heat source input pipeline is natural gas or steam.

[0011] Secondly, the present invention provides a heating method for a pressure-reducing station with flexibly adjustable temperature differences, using a pressure-reducing station heating system with flexibly adjustable temperature differences, comprising the following steps: Primary network circulation heat exchange steps: The primary network heating network supply water is input into the primary side of the plate heat exchanger, and after completing the primary heat exchange and cooling with the secondary network medium, it is output; the output primary network medium is divided into two paths. The first path enters the primary side of the absorption heat pump through the first regulating valve, and after completing the secondary heat exchange and cooling, it is output to the primary network heating network return water end. The second path flows along the primary side bypass pipeline through the fourth regulating valve and merges into the primary network heating network return water end. Secondary network circulation heat exchange steps: The secondary network heat return water is divided into two paths. The first path enters the secondary side of the plate heat exchanger through the second regulating valve, exchanges heat with the primary network medium, and is then output after heating. The second path enters the secondary side of the absorption heat pump through the third regulating valve, absorbs heat, and is then output after heating. The two heated secondary network media are combined and output to the secondary network heat supply end. Temperature difference adjustment steps: Adjust the flow ratio of the two streams of the primary network medium by adjusting the opening of the first and fourth regulating valves; adjust the flow ratio of the two streams of the secondary network medium by adjusting the opening of the second and third regulating valves, thus completing the temperature difference adjustment of the heating system.

[0012] Furthermore, in the temperature difference adjustment step, the method for adjusting the return water temperature of the primary network water circuit is as follows: By adjusting the opening of the first and fourth regulating valves, the ratio of the medium flow rate through the primary side of the absorption heat pump to the medium flow rate through the primary side bypass pipeline is adjusted, thereby completing the regulation of the return water temperature of the primary network water circuit.

[0013] Furthermore, in the temperature difference adjustment step, the method for adjusting the water supply temperature of the secondary network water circuit is as follows: By adjusting the opening of the second and third regulating valves, the ratio of the medium flow rate through the secondary side of the plate heat exchanger to the medium flow rate through the secondary side of the absorption heat pump is adjusted, thereby regulating the water supply temperature of the secondary network water circuit.

[0014] Furthermore, the operating modes of the pressure relief station heating system include independent operation mode of plate heat exchanger and joint operation mode of plate heat exchanger and absorption heat pump.

[0015] Furthermore, the operating mode of the pressure relief station heating system can be switched by adjusting the opening degree of the first regulating valve, the fourth regulating valve, the second regulating valve, and the third regulating valve.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a flexible temperature-adjustable pressure-difference heating system that combines a plate heat exchanger with an absorption heat pump. The primary side water flow operates in series, while the secondary side water flow operates in parallel. Under this system, a large temperature difference heating can be achieved on the primary side, while the secondary side maintains the original temperature difference and flow rate of the urban pipe network, without requiring extensive modifications to the terminal heat exchange stations. It is suitable for application scenarios where there is an urgent need to expand heating capacity, but the urban heating network is limited. Meeting practical engineering needs, it combines traditional pressure-difference station equipment with an absorption heat pump and regulating valves to achieve a flexible heating system that allows for large temperature difference operation of the primary pipe network while maintaining the flow rate and operating at a normal temperature difference in the secondary pipe network.

[0017] Furthermore, the primary side of the heating network operates in series with an absorption heat pump via a plate heat exchanger to achieve heat release with a large temperature difference. The secondary side of the heating network operates in parallel with an absorption heat pump via a plate heat exchanger to achieve heat release with a normal flow rate and normal temperature difference. The secondary side of the heating network does not need to be upgraded to a large temperature difference heat exchange station through other means, such as modifying the terminal heat exchange station to a large temperature difference heat exchange station, and can directly match the large temperature difference operation of the primary side.

[0018] Furthermore, when the heating load changes, this system can control the flow rate of water entering the absorption heat pump and the bypass water flow rate on the primary side through the first and fourth regulating valves, and even completely disconnect the absorption heat pump; and control the flow rate of water entering the absorption heat pump on the secondary side through the second and third regulating valves, and even completely disconnect the absorption heat pump. The above adjustment process can realize the maximum temperature difference condition, the temperature difference adjustment condition, and the minimum temperature difference condition, flexibly adjust the primary side temperature difference, and thus flexibly adjust the heating load. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of a pressure-reducing station heating system with adjustable temperature difference, provided by the present invention.

[0021] Wherein, 1 is a plate heat exchanger, 2 is an absorption heat pump, 3 is a driving heat source, V1 is the first regulating valve, V2 is the second regulating valve, V3 is the third regulating valve, and V4 is the fourth regulating valve. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Example 1 A pressure-reducing station heating system with flexible temperature difference adjustment includes a plate heat exchanger 1, an absorption heat pump 2, and a regulating valve group; the pressure-reducing station heating system is divided into a primary network water circuit and a secondary network water circuit that are independent of each other; Temperature sensors and flow sensors are installed at the primary input, primary output, secondary input, and secondary output ends of plate heat exchanger 1, and at the primary input, primary output, secondary input, and secondary output ends of absorption heat pump 2. The temperature and flow sensors are respectively located at the inlet and outlet of plate heat exchanger 1 and absorption heat pump 2 to monitor the temperature and flow parameters of each water path in real time, providing data support for system regulation and control.

[0027] Plate heat exchanger 1 is the basic heat exchange device of the system, used to realize heat transfer between the primary and secondary water networks. Its primary and secondary sides are isolated from each other, and only heat exchange occurs without media mixing. Driven by the heat source 3, absorption heat pump 2 deeply recovers the waste heat in the primary water network and delivers the heat to the secondary water network to increase the heating temperature difference and improve the heating capacity.

[0028] In the primary network water circuit, the primary side of plate heat exchanger 1 is connected in series with the primary side of absorption heat pump 2; the primary side input end of plate heat exchanger 1 is connected to the primary network water supply end; the primary side output end of plate heat exchanger 1 is connected to the primary side input end of absorption heat pump 2; the primary side output end of absorption heat pump 2 is connected to the primary network water return end; a primary side bypass pipeline is provided between the primary side output end of plate heat exchanger 1 and the primary side output end of absorption heat pump 2. In the secondary network water circuit, the secondary side of plate heat exchanger 1 and the secondary side of absorption heat pump 2 are arranged in parallel; the return water end of the secondary network heat network is divided into two paths, the first path is connected to the secondary side input end of plate heat exchanger 1, and the second path is connected to the secondary side input end of absorption heat pump 2; the secondary side output end of plate heat exchanger 1 and the secondary side output end of absorption heat pump 2 are connected to the secondary network heat network water supply end after they merge. The primary network water circuit is a heat source-side circulating water circuit, independent of the secondary network water circuit. The primary side of plate heat exchanger 1 and the primary side of absorption heat pump 2 are arranged in series. The primary network heat supply water flows sequentially through plate heat exchanger 1 and absorption heat pump 2, achieving cascade heat release and reducing the primary network return water temperature. A primary side bypass pipe is installed between the primary side output end of plate heat exchanger 1 and the primary side output end of absorption heat pump 2 to regulate the flow rate of the medium flowing through the primary side of absorption heat pump 2.

[0029] The secondary network water circuit is a user-side circulating water circuit, independent of the primary network water circuit. The secondary side of plate heat exchanger 1 and the secondary side of absorption heat pump 2 are arranged in parallel. The return water of the secondary network heat network is divided into two paths, which enter the secondary side of plate heat exchanger 1 and the secondary side of absorption heat pump 2 respectively for heating. The heated media merge to form the secondary network heat network water supply, realizing flexible adjustment of the secondary network water supply temperature.

[0030] The primary side heating network supply water flows sequentially through plate heat exchanger 1 and absorption heat pump 2, that is, the primary side of plate heat exchanger 1 and absorption heat pump 2 are connected in series. The secondary side heating network return water flows in two separate paths to plate heat exchanger 1 and absorption heat pump 2, that is, the secondary side heating network return water plate heat exchanger 1 and absorption heat pump 2 are connected in parallel.

[0031] The regulating valve assembly includes a first regulating valve V1, a second regulating valve V2, a third regulating valve V3, and a fourth regulating valve V4. The first regulating valve V1 is located at the primary side input end of the absorption heat pump 2 and is used to control the flow rate of the primary network medium flowing into the primary side of the absorption heat pump 2. The fourth regulating valve V4 is located on the primary side bypass pipeline and is used to control the bypass flow rate of the primary network medium. By adjusting the opening ratio of the first regulating valve V1 and the fourth regulating valve V4, the return water temperature of the primary network and the heating temperature difference can be regulated. The second regulating valve V2 is located at the secondary side input end of the plate heat exchanger 1 and is used to control the flow rate of the secondary network medium flowing into the secondary side of the plate heat exchanger 1. The third regulating valve V3 is located at the secondary side input end of the absorption heat pump 2 and is used to control the flow rate of the secondary network medium flowing into the secondary side of the absorption heat pump 2.

[0032] The temperature of the secondary network water supply and the heating load can be adjusted by regulating the opening ratio of the second regulating valve V2 and the third regulating valve V3.

[0033] Absorption heat pump 2 is a lithium bromide absorption heat pump. The lithium bromide heat pump unit includes a high-temperature generator, a low-temperature generator, a heat pump absorber, a heat pump evaporator, a heat pump condenser, a high-temperature solution heat exchanger, and a low-temperature solution heat exchanger. The hot side of the high-temperature generator and the high-temperature solution heat exchanger, and the heat pump absorber are connected in sequence. The solution outlet of the heat pump absorber is connected to the cold side of the high-temperature solution heat exchanger and the solution inlet of the high-temperature generator. The solution outlet of the heat pump absorber is also connected in sequence to the cold side of the low-temperature solution heat exchanger and the solution inlet of the low-temperature generator. The hot side of the low-temperature generator, the hot side of the low-temperature solution heat exchanger, and the heat pump absorber are connected in sequence. The high-temperature generator, the low-temperature generator, the heat pump condenser, the heat pump evaporator, and the heat pump absorber are connected in sequence. One branch of the secondary network piping enters the heat pump absorber and the heat pump condenser respectively, collectively referred to as the secondary side of absorption heat pump 2; the primary network piping enters the evaporator, collectively referred to as the primary side of absorption heat pump 2.

[0034] The absorption heat pump 2 is connected to the input pipeline of the driving heat source 3, and the supply medium of the input pipeline of the driving heat source 3 is natural gas or steam. The driving heat source 3 provides driving energy for the absorption heat pump 2. Its supply medium is natural gas or steam, which provides power for the cycle work of the absorption heat pump 2.

[0035] Example 2 A method for heating a pressure-reducing station with flexible temperature difference adjustment, using a pressure-reducing station heating system with flexible temperature difference adjustment as described in Example 1, includes the following steps: Primary network circulation heat exchange steps: The primary network heating network supply water is input into the primary side of the plate heat exchanger 1, and after completing the primary heat exchange and cooling with the secondary network medium, it is output; the output primary network medium is divided into two paths. The first path enters the primary side of the absorption heat pump 2 through the first regulating valve V1, and after completing the secondary heat exchange and cooling, it is output to the primary network heating network return water end. The second path flows along the primary side bypass pipeline through the fourth regulating valve V4 and merges into the primary network heating network return water end. Secondary network circulation heat exchange steps: The return water of the secondary network is divided into two paths. The first path enters the secondary side of the plate heat exchanger 1 through the second regulating valve V2, exchanges heat with the primary network medium, and is then output after heating. The second path enters the secondary side of the absorption heat pump 2 through the third regulating valve V3, absorbs heat, and is then output after heating. The heated secondary network medium from both paths is combined and output to the secondary network heating network water supply end. Temperature difference adjustment steps: Adjust the flow ratio of the two streams of the primary network medium by adjusting the opening of the first regulating valve V1 and the fourth regulating valve V4; adjust the flow ratio of the two streams of the secondary network medium by adjusting the opening of the second regulating valve V2 and the third regulating valve V3, and complete the temperature difference adjustment of the heating system.

[0036] In the temperature difference adjustment process, the method for adjusting the return water temperature of the primary network water circuit is as follows: By adjusting the opening of the first regulating valve V1 and the fourth regulating valve V4, the ratio of the medium flow rate through the primary side of the absorption heat pump 2 to the medium flow rate through the primary side bypass pipeline is adjusted, thereby completing the adjustment of the return water temperature of the primary network water circuit.

[0037] In the temperature difference adjustment process, the method for adjusting the water supply temperature of the secondary network water circuit is as follows: By adjusting the opening of the second regulating valve V2 and the third regulating valve V3, the ratio of the medium flow rate through the secondary side of the plate heat exchanger 1 to the medium flow rate through the secondary side of the absorption heat pump 2 is adjusted, thereby completing the regulation of the water supply temperature of the secondary network water circuit.

[0038] The operating modes of the pressure relief station heating system include the independent operation mode of plate heat exchanger 1 and the combined operation mode of plate heat exchanger 1 and absorption heat pump 2.

[0039] The operating mode of the pressure relief station heating system is switched by adjusting the opening of the first regulating valve V1, the fourth regulating valve V4, the second regulating valve V2, and the third regulating valve V3.

[0040] Example 3 A flexible temperature difference-adjustable pressure-reducing station heating method combines a plate heat exchanger 1 with an absorption heat pump 2, dividing the system into two circulating water circuits: a primary network hot water side and a secondary network hot water side. Figure 1 As shown.

[0041] For the primary hot water side, plate heat exchanger 1 and absorption heat pump 2 are connected in series. Regulating valves V1 and V4 are installed on the primary side inlet and the primary side inlet / outlet bypass pipes of absorption heat pump 2, respectively. The primary side high-temperature heating network water is supplied at 130℃, and the entire flow rate passes through the primary side of plate heat exchanger 1 for the first heat exchange. After the heat exchange, the temperature of the primary side heating network water drops to 70℃, and then passes through the evaporator of absorption heat pump 2 for a second cooling. When the primary side heating network water passes through absorption heat pump 2, the flow rate into the evaporator and the bypass flow rate of absorption heat pump 2 are controlled by valves V1 and V4. When valve V1 is fully closed and valve V4 is fully open, the full flow of primary side heating network water passes through absorption heat pump 2. This corresponds to the maximum temperature difference condition, where the primary network heat release load is the maximum, and the primary side heating network water is cooled to 30℃ for return. When valve V1 is partially open and valve V4 is partially closed, a portion of the primary side heating network water flows through absorption heat pump 2, and the remaining flow is directly bypassed and mixed with the primary side outlet water of absorption heat pump 2. This corresponds to the temperature difference adjustment condition, where the primary network heat release load is moderate, and the primary side heating network water is cooled to between 30℃ and 70℃ for return. When valve V1 is fully open and valve V4 is fully closed, the primary side heating network water does not pass through absorption heat pump 2. This corresponds to the normal temperature difference condition, where the primary network heat release load is the minimum, and the primary side heating network water is directly returned at 70℃.

[0042] For the secondary side heating network water, plate heat exchanger 1 and absorption heat pump 2 are connected in parallel. Regulating valves V2 and V3 are installed at the secondary side inlet of plate heat exchanger 1 and the secondary side inlet of absorption heat pump 2, respectively. The secondary side low-temperature heating network return water is 50°C and is divided into two paths, passing through the secondary side of plate heat exchanger 1 and the absorber and condenser of absorption heat pump 2, respectively. One path, after passing through the secondary side of plate heat exchanger 1, heats the secondary side heating network water to 110°C; the other path, after passing through the absorber and condenser of absorption heat pump 2, heats the secondary side heating network water to approximately 80°C. The two heated secondary side heating network waters are mixed to ultimately form a 100°C secondary side heating network supply water. When the secondary heating network water is divided into two paths, the flow rate into the absorber and condenser of absorption heat pump 2 is controlled by valves V2 and V3. When valve V2 is partially open and valve V3 is partially closed, it corresponds to the maximum temperature difference condition and the regulating temperature difference condition. When valve V2 is fully open and valve V3 is fully closed, the secondary heating network water does not pass through absorption heat pump 2, which corresponds to the normal temperature difference condition, and the heat absorbed by the secondary network is minimal. Under normal circumstances, there is no situation where valve V3 is fully open and valve V2 is fully closed.

[0043] Figure 1T1-T3 and t1-t4 are respectively: (1) Primary water network (heat source side, upper pipeline) T1℃: Primary heating network water supply temperature (primary side inlet temperature of plate heat exchanger 1) T2℃: The outlet temperature of the water after heat exchange in the primary network through plate heat exchanger 1 (primary side outlet temperature of plate heat exchanger 1). T3℃: The final return water temperature of the primary network (the temperature at which the water returns to the heat source after mixing with the bypass pipeline at the primary side outlet of absorption heat pump 2). Q1t / h: Total flow rate of water supplied by the primary network Q2t / h: Total return water flow rate of the primary network (equal to Q1, the system is a closed loop). (2) Secondary water network (user side, lower pipeline) t1℃: Secondary heating network return water temperature (user-side return water temperature entering the system) t2℃: The outlet temperature of the water after heating by the absorption heat pump 2 (secondary side outlet temperature of absorption heat pump 2). t3℃: The outlet temperature of the water from the secondary network after being heated by plate heat exchanger 1 (secondary side outlet temperature of plate heat exchanger 1). t4℃: The final water supply temperature of the secondary network (the temperature at which the water from the secondary side of plate heat exchanger 1 is mixed with the water from the secondary side of absorption heat pump 2 and supplied to the user). The present invention adjusts V4 / V1: changing the flow ratio of the primary network through the absorption heat pump 2, thereby controlling T3 (primary network return water temperature) and the primary network heat release depth.

[0044] Adjusting V2 / V3: Changing the flow ratio of the secondary network through plate heat exchanger 1 and absorption heat pump 2, thereby controlling t4 (secondary network water supply temperature) and total heating load.

[0045] The absorption heat pump 2 includes a high-temperature generator, a low-temperature generator, a heat pump absorber, a heat pump evaporator, a heat pump condenser, a high-temperature solution heat exchanger, and a low-temperature solution heat exchanger. The high-temperature generator, the hot side of the high-temperature solution heat exchanger, and the heat pump absorber are connected in sequence. The solution outlet of the heat pump absorber is connected to the cold side of the high-temperature solution heat exchanger and the solution inlet of the high-temperature generator. The solution outlet of the heat pump absorber is also connected in sequence to the cold side of the low-temperature solution heat exchanger and the solution inlet of the low-temperature generator. The hot side of the low-temperature generator, the hot side of the low-temperature solution heat exchanger, and the heat pump absorber are connected in sequence. The high-temperature generator, the low-temperature generator, the heat pump condenser, the heat pump evaporator, and the heat pump absorber are connected in sequence. One branch of the secondary heat network pipeline is connected to the heat pump absorber and the heat pump condenser respectively. The high-temperature generator is driven by steam or gas. For the primary heat network water, the primary heat network water flowing out of the plate heat exchanger 1 enters the evaporator to release heat and cool down again. The heat network water return flows through the heat pump condenser and the heat pump absorber to absorb heat. On the solution side, the dilute lithium bromide solution in the high-temperature and low-temperature generators absorbs heat and heats to become a concentrated solution. This concentrated solution then passes through the high-temperature and low-temperature solution heat exchangers respectively before entering the heat pump absorber, simultaneously generating refrigerant vapor. The refrigerant vapor enters the heat pump condenser, releases heat, and condenses into refrigerant water, which then enters the heat pump evaporator. The refrigerant water absorbs heat and evaporates into low-temperature refrigerant vapor in the evaporator. This low-temperature refrigerant vapor then enters the heat pump absorber where it is absorbed by the concentrated solution, releasing heat.

[0046] It should be noted that the maximum temperature difference condition, the regulating temperature difference condition, and the minimum temperature difference condition correspond to the heat release load on the primary side, which is also the heat absorption load on the secondary side, and also correspond to the heating load supplied by the heating network to the heat users. The flexibility of this system lies in the fact that the heating load can be adjusted through the maximum temperature difference condition, the regulating temperature difference condition, and the minimum temperature difference condition.

[0047] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing and the full scope of its equivalents. For purposes of completeness, all articles and references, including disclosures in patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0048] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the defined protection scope of the present invention.

Claims

1. A pressure-reducing station heating system with flexibly adjustable temperature difference, characterized in that, It includes a plate heat exchanger (1), an absorption heat pump (2), and a regulating valve group; the heating system of the pressure isolation station is divided into a primary network water circuit and a secondary network water circuit that are independent of each other; In the primary network water circuit, the primary side of the plate heat exchanger (1) is connected in series with the primary side of the absorption heat pump (2); the primary side input end of the plate heat exchanger (1) is connected to the primary network water supply end; the primary side output end of the plate heat exchanger (1) is connected to the primary side input end of the absorption heat pump (2); the primary side output end of the absorption heat pump (2) is connected to the primary network water return end; a primary side bypass pipeline is provided between the primary side output end of the plate heat exchanger (1) and the primary side output end of the absorption heat pump (2); In the secondary network water circuit, the secondary side of the plate heat exchanger (1) and the secondary side of the absorption heat pump (2) are arranged in parallel; the return water end of the secondary network heat network is divided into two paths, the first path is connected to the secondary side input end of the plate heat exchanger (1), and the second path is connected to the secondary side input end of the absorption heat pump (2); the secondary side output end of the plate heat exchanger (1) and the secondary side output end of the absorption heat pump (2) are combined and then connected to the secondary network heat network water supply end; The regulating valve group includes a first regulating valve (V1), a second regulating valve (V2), a third regulating valve (V3), and a fourth regulating valve (V4). The first regulating valve (V1) is located at the primary input end of the absorption heat pump (2); The fourth regulating valve (V4) is installed on the primary bypass pipeline; The second regulating valve (V2) is located at the secondary side input end of the plate heat exchanger (1); The third regulating valve (V3) is located at the secondary input end of the absorption heat pump (2).

2. The pressure-reducing station heating system with flexibly adjustable temperature difference according to claim 1, characterized in that, Temperature sensors and flow sensors are provided at the primary input end, primary output end, secondary input end and secondary output end of the plate heat exchanger (1), and at the primary input end, primary output end, secondary input end and secondary output end of the absorption heat pump (2).

3. The pressure-reducing station heating system with flexible temperature difference adjustment according to claim 1, characterized in that, The absorption heat pump (2) is a lithium bromide absorption heat pump.

4. The pressure-reducing station heating system with flexibly adjustable temperature difference according to claim 1, characterized in that, The absorption heat pump (2) is connected to the input pipeline of the driving heat source (3).

5. A pressure-reducing station heating system with flexibly adjustable temperature difference according to claim 4, characterized in that, The supply medium of the input pipeline of the driving heat source (3) is natural gas or steam.

6. A heating method for a pressure-reducing station with flexible temperature difference adjustment, characterized in that, The heating system of a pressure-reducing station with flexible temperature difference adjustment as described in any one of claims 1-5 includes the following steps: Primary heat exchange process: The primary heat exchange water is fed into the primary side of the plate heat exchanger (1), and after completing the primary heat exchange and cooling with the secondary heat exchange medium, it is output; The output primary heat exchange medium is divided into two paths. The first path enters the primary side of the absorption heat pump (2) through the first regulating valve (V1), and after completing the secondary heat exchange and cooling, it is output to the primary heat exchange return water end. The second path flows along the primary side bypass pipeline through the fourth regulating valve (V4) and merges into the primary heat exchange return water end. Secondary network circulation heat exchange steps: The return water of the secondary network heat network is divided into two paths. The first path enters the secondary side of the plate heat exchanger (1) through the second regulating valve (V2), exchanges heat with the primary network medium and is heated before being output. The second path enters the secondary side of the absorption heat pump (2) through the third regulating valve (V3), absorbs heat and is heated before being output. The heated secondary network medium from the two paths merges and is output to the secondary network heat network water supply end. Temperature difference adjustment steps: Adjust the flow ratio of the two streams of the primary network medium by adjusting the opening of the first regulating valve (V1) and the fourth regulating valve (V4); adjust the flow ratio of the two streams of the secondary network medium by adjusting the opening of the second regulating valve (V2) and the third regulating valve (V3), and complete the temperature difference adjustment of the heating system.

7. A heating method for a pressure-reducing station with flexibly adjustable temperature difference according to claim 6, characterized in that, In the temperature difference adjustment step, the method for adjusting the return water temperature of the primary network water circuit is as follows: By adjusting the opening of the first regulating valve (V1) and the fourth regulating valve (V4), the ratio of the medium flow rate through the primary side of the absorption heat pump (2) to the medium flow rate through the primary side bypass pipeline is adjusted, thereby completing the adjustment of the return water temperature of the primary network water circuit.

8. A heating method for a pressure-reducing station with flexibly adjustable temperature difference according to claim 6, characterized in that, In the temperature difference adjustment step, the method for adjusting the water supply temperature of the secondary network water circuit is as follows: By adjusting the opening of the second regulating valve (V2) and the third regulating valve (V3), the ratio of the medium flow rate through the secondary side of the plate heat exchanger (1) to the medium flow rate through the secondary side of the absorption heat pump (2) is adjusted, thereby completing the adjustment of the water supply temperature of the secondary network water circuit.

9. A heating method for a pressure-reducing station with flexibly adjustable temperature difference according to claim 6, characterized in that, The operation modes of the pressure relief station heating system include the independent operation mode of the plate heat exchanger (1) and the joint operation mode of the plate heat exchanger (1) and the absorption heat pump (2).

10. A pressure-reducing station heating system with flexibly adjustable temperature difference according to claim 9, characterized in that, The operating mode of the pressure relief station heating system is switched by adjusting the opening degree of the first regulating valve (V1), the fourth regulating valve (V4), the second regulating valve (V2), and the third regulating valve (V3).

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