Steam heat pump system with air injection bypass line

Abstract

The utility model discloses a steam heat pump system with air supplement bypass pipeline, comprising: evaporator group, primary compressor and secondary compressor connected in proper order, primary compressor is equipped with primary air supplement device, and primary air supplement device includes flasher, and flasher is connected between evaporator group and the suction port of primary compressor through air supplement bypass pipeline, and secondary compressor is equipped with secondary cooling device for cooling the shell. Evaporator group is composed of primary evaporator and secondary evaporator, and the refrigerant sent by primary evaporator is sent to the suction port of primary compressor through secondary evaporator, and the inlet of air supplement bypass pipeline is connected on the refrigerant pipeline between primary evaporator and secondary evaporator. The utility model introduces two stage compression frame, and is equipped with primary air supplement device and secondary cooling device for two stage compressor respectively, realizes the high -efficient stable operation of steam heat pump system under the multiple variable conditions.

Description

Technical Field

[0001] This utility model relates to the field of heat pump system technology, and in particular to a steam heat pump system with a gas supply bypass pipeline. Background Technology

[0002] In industrial production, steam, as a key energy carrier, is widely used in processes such as chemical engineering, food processing, and textile manufacturing to provide heat and power for equipment. Traditional steam generation methods mainly rely on burning fossil fuels such as coal and natural gas, which is not only inefficient in energy use but also generates large amounts of carbon dioxide emissions, exacerbating environmental pollution. At the same time, the high operating costs make it difficult to meet the urgent global demand for energy conservation, emission reduction, and green manufacturing.

[0003] To address this challenge, high-temperature heat pump steam technology has emerged. This technology extracts heat energy from low-temperature heat sources such as industrial wastewater and ambient air by consuming a small amount of electricity and converts it into high-temperature steam. Theoretically, it has significant energy-saving and environmental advantages. However, existing high-temperature heat pump steam systems still face a series of technical bottlenecks in practical applications, which severely limit their large-scale industrial promotion.

[0004] First, traditional high-temperature heat pumps mostly use a single-stage compression cycle. The single-stage compression structure cannot effectively adapt to the changing heat source temperature and load demand. Especially when the heat source temperature fluctuates, the COP value fluctuates greatly, resulting in low overall energy efficiency, which cannot meet the strict requirements of industrial fields for efficient energy utilization.

[0005] Secondly, the system is not adaptable enough to changing operating conditions. In actual operation, changes in heat source temperature, flow rate, and environmental conditions can cause significant fluctuations in return gas superheat, which can easily lead to liquid return problems, causing compressor liquid slugging, lubrication failure, and other malfunctions, significantly shortening equipment life.

[0006] Therefore, how to design a steam heat pump system that can improve energy efficiency and enhance adaptability to operating conditions is a technical problem that the industry urgently needs to solve. Utility Model Content

[0007] To address the shortcomings of existing technologies, such as low energy efficiency ratio and insufficient adaptability to operating conditions, this invention proposes a steam heat pump system with a gas injection bypass pipeline. By introducing a two-stage compression architecture, a first-stage gas injection device and a second-stage cooling device are respectively configured for the two-stage compressors, thereby achieving efficient and stable operation of the steam heat pump system under varying operating conditions.

[0008] The technical solution adopted in this utility model is to design a steam heat pump system with a gas replenishment bypass pipeline, including: an evaporator group, a primary compressor and a secondary compressor connected in sequence; the primary compressor is equipped with a primary gas replenishment device, which includes a flash evaporator, which is connected between the evaporator group and the suction port of the primary compressor through the gas replenishment bypass pipeline; the secondary compressor is equipped with a secondary cooling device for cooling the shell.

[0009] Furthermore, the evaporator assembly consists of a primary evaporator and a secondary evaporator. The refrigerant delivered from the primary evaporator is sent to the suction port of the primary compressor through the secondary evaporator. The inlet of the make-up gas bypass pipeline is connected to the refrigerant pipeline between the primary evaporator and the secondary evaporator.

[0010] In some embodiments of this utility model, the primary evaporator adopts a shell-and-tube heat exchanger, and the secondary evaporator adopts a microchannel heat exchanger.

[0011] Furthermore, the primary gas replenishment device also includes a spiral guide plate, through which the refrigerant delivered by the flash evaporator is sent to the suction port of the primary compressor.

[0012] In some embodiments of this utility model, the secondary cooling device includes: a shell cooling water circulation system and / or a phase change material heat storage bag that contacts and transfers heat with the secondary compressor; wherein, the shell cooling water circulation system includes cooling pipes arranged around the shell of the secondary compressor, and a water pump that drives the cooling water to flow in the cooling pipes.

[0013] Furthermore, the steam heat pump system also includes: a heat source delivery pipe for providing heat to the evaporator group, the heat source delivery pipe exchanging heat with the evaporator in the evaporator group successively, and the heat source delivery pipe being connected to the heat source input pipe through a switching device.

[0014] In some embodiments of this utility model, the heat source input pipeline includes at least two of the following: an industrial hot water pipeline, an air pipeline, and a solar hot water pipeline; wherein, the industrial hot water pipeline is used to connect to an industrial wastewater heat source, the air pipeline is used to connect to an ambient air heat source, and the solar hot water pipeline is used to connect to a solar hot water heat source.

[0015] Furthermore, the steam heat pump system also includes a steam ejector mixer, which has a low-pressure inlet, a high-pressure inlet, and a steam outlet. The low-pressure inlet is connected to the outlet of the evaporator assembly, and the high-pressure inlet is connected to the exhaust port of the secondary compressor.

[0016] Furthermore, an intercooler and a steam generator are provided between the exhaust port of the secondary compressor and the high-pressure inlet of the steam ejector mixer, with the intercooler located upstream of the steam generator.

[0017] In some embodiments of this invention, the steam ejector mixer also has a pressure regulating inlet connected to an external gas supply station.

[0018] Compared with existing technologies, this invention adopts two-stage compression, which decomposes a large compression ratio into two smaller compression ratios, reducing the load and exhaust temperature of each stage compressor, enabling the system to efficiently adapt to high-temperature steam output conditions, and fundamentally improving the system's energy efficiency ratio.

[0019] The first-stage injection gas system utilizes the medium-pressure liquid refrigerant exiting the evaporator for flash evaporation. The resulting intermediate-pressure gas (injection gas) mixes with the low-temperature, low-pressure vapor from the evaporator assembly before entering the first-stage compressor. This stabilizes the compressor's suction state and enhances the system's adaptability to varying operating conditions such as heat source temperature and load changes. Simultaneously, the low-temperature characteristics of the injection gas help lower the first-stage compressor's suction temperature, reducing overheating losses during compression and indirectly lowering compression work. The second-stage injection gas system actively cools the second-stage compressor casing, preventing lubricating oil carbonization and efficiency loss, maintaining high-efficiency compressor operation to support COP improvement and operational adaptability. Attached Figure Description

[0020] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein: Figure 1 This is a connection diagram of the steam heat pump system of this utility model; Figure 2 This is a schematic diagram of the operation mode of the primary gas replenishment device of this utility model; Figure 3 This is a schematic diagram of the operation mode of the two-stage cooling device of this utility model; Figure 4 This is a schematic diagram of the connection of a steam heat pump system in some embodiments of this utility model; Figure 5 This is a schematic diagram of the heat source selection for this utility model; Figure 6 This is a schematic diagram of the connection of the steam heat pump system in a preferred embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Primary compressor; 2. Secondary compressor; 3. Primary evaporator; 4. Secondary evaporator; 5. Primary gas supply device; 6. Secondary cooling device; 7. Switching device; 8. Evaporator ejector mixer; 9. Intercooler; 10. Steam generator. Detailed Implementation

[0021] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0022] like Figure 1 As shown, this utility model proposes a steam heat pump system with a gas supply bypass pipeline. The steam heat pump system includes an evaporator assembly, a primary compressor 1, and a secondary compressor 2. The steam heat pump system employs two-stage compression, decomposing a large compression ratio into two smaller compression ratios, reducing the load and exhaust temperature of each compressor stage, enabling the system to efficiently adapt to high-temperature steam output conditions, and fundamentally improving the system's energy efficiency ratio. Furthermore, the primary compressor 1 is equipped with a primary gas supply device 5, which supplies gas to the primary compressor 1. The secondary compressor 2 is equipped with a secondary cooling device 6, which cools the casing of the secondary compressor 2.

[0023] Specifically, the primary gas injection device 5 includes a flash evaporator, which is connected between the evaporator assembly and the suction port of the primary compressor 1 via a gas injection bypass pipeline. The primary gas injection device 5 directly delivers the injection gas generated by the flash evaporator to the suction port of the primary compressor 1. The injection gas (usually medium-pressure saturated vapor) mixes with the low-temperature, low-pressure vapor delivered from the evaporator assembly before entering the primary compressor 1, which increases the suction mass flow rate, thereby increasing the refrigerant circulation volume of the system and enhancing the overall cooling capacity.

[0024] The low-temperature characteristics of the supplemental gas help lower the suction temperature of the first-stage compressor 1, reducing superheat losses during compression and indirectly reducing compression work. The flash evaporator acts as a high-efficiency gas-liquid separator in the supplemental gas bypass line. When heat source fluctuations cause a decrease in the superheat of the return gas at the evaporator outlet (containing droplets), the gas-liquid mixture first enters the flash evaporator. The liquid refrigerant is separated and returned to the main cycle, while only saturated or superheated vapor is sent to the suction port of the first-stage compressor 1 through the supplemental gas bypass line. This avoids the risk of "liquid return" or "liquid slugging" caused by liquid refrigerant entering the compressor, protecting the compressor's lifespan. Simultaneously, the supplemental gas bypass line provides a system buffer, making the suction state of the first-stage compressor 1 more stable and enhancing the system's adaptability to varying operating conditions such as heat source temperature and load changes.

[0025] The secondary air supply device 6 stabilizes the compressor operating temperature by actively cooling the casing of the secondary compressor 2, reducing overheating fluctuations, preventing lubricating oil carbonization and efficiency loss, maintaining the compressor's high-efficiency operation, and further supporting COP improvement and operating condition adaptability.

[0026] In some embodiments of this utility model, the evaporator group consists of a primary evaporator 3 and a secondary evaporator 4. The primary evaporator 3 is connected to the outlet of the condenser, and the secondary evaporator 4 is connected between the primary evaporator 3 and the primary compressor 1. The refrigerant delivered by the primary evaporator 3 is sent to the suction port of the primary compressor 1 through the secondary evaporator 4. The inlet of the gas bypass pipeline is connected to the refrigerant pipeline between the primary evaporator 3 and the secondary evaporator 4.

[0027] The primary evaporator 3 first receives high-temperature liquid refrigerant from the condenser and utilizes the highest temperature portion of the heat source for efficient evaporation, producing medium-temperature, medium-pressure refrigerant vapor. Subsequently, as the heat source temperature decreases, the refrigerant enters the secondary evaporator 4, where it utilizes the medium-temperature portion of the heat source for secondary evaporation, further extracting heat. This series heat exchange design matches the heat source temperature with the evaporator's requirements, reducing irreversible heat transfer losses and effectively improving heat source utilization.

[0028] Because the inlet of the make-up gas bypass line is connected to the refrigerant line between the primary evaporator 3 and the secondary evaporator 4, when the refrigerant superheat at the outlet of the primary evaporator 3 is insufficient (e.g., due to heat source fluctuations causing some liquid refrigerant residue), the gas-liquid mixture can be introduced into the flash evaporator through the make-up gas bypass line for gas-liquid separation. The separated vapor is then sent as make-up gas to the suction port of the first-stage compressor 1, while the liquid returns to the main cycle. This completely eliminates the risk of liquid refrigerant entering the compressor, solves the problem of "return gas superheat fluctuations causing liquid return" in the background technology, and extends the compressor's lifespan.

[0029] In addition, a makeup gas bypass line extracts refrigerant between the primary evaporator 3 and the secondary evaporator 4, generates makeup gas through a flash evaporator, and sends it to the suction port of the first-stage compressor 1. The makeup gas (medium-pressure saturated vapor) mixes with the low-temperature, low-pressure vapor from the secondary evaporator 4 before entering the first-stage compressor 1, increasing the suction mass flow rate and lowering the suction temperature, thus reducing compression work. Combined with the subcooling advantage of the two-stage evaporation, this improves the overall system COP and effectively solves the problem of "low system efficiency ratio" in the background technology.

[0030] Based on the two-stage evaporation structure, the preferred design uses the primary evaporator 3 as the main evaporator, employing a shell-and-tube heat exchanger (with a heat transfer coefficient within a certain range, such as 3000-4000 W / m²・K). The shell-and-tube heat exchanger enables stable and efficient heat exchange, ensuring basic evaporation efficiency. The secondary evaporator 4 uses a microchannel heat exchanger (with fin spacing within a certain range, such as 1.8-3.0 mm). After primary evaporation, the refrigerant becomes a medium-pressure gas-liquid mixture, and the heat source temperature decreases accordingly. The microchannel heat exchanger exhibits extremely high heat transfer efficiency at low temperatures and small temperature differences. Its large specific surface area and compact structure fully utilize the waste heat of the heat source, completely evaporating and moderately superheating the refrigerant, maximizing the extraction of heat from the heat source, thereby significantly improving the overall energy efficiency ratio of the system.

[0031] To enhance the refrigerant supply effect of the first-stage refrigerant supply device 5, it also includes a spiral guide plate. The refrigerant from the flash evaporator is delivered to the suction port of the first-stage compressor 1 via the spiral guide plate. The refrigerant from the flash evaporator is typically a saturated vapor or a gas-liquid mixture containing a small amount of liquid droplets, while the refrigerant from the evaporator assembly may be in a superheated or saturated state. The spiral guide plate generates a swirling effect through its spiral structure, forcing refrigerants from different sources and in different states to mix thoroughly, avoiding gas-liquid stratification or temperature gradients. This ensures that the refrigerant entering the suction port of the first-stage compressor is highly uniform in temperature, pressure, and dryness, reducing localized overcooling or overheating and providing stable suction conditions for the compressor. Furthermore, through the thorough mixing by the spiral guide plate, potential droplets are refined and uniformly dispersed in the gas phase, preventing liquid refrigerant from concentrating and entering the compressor suction port, thus reducing the risk of liquid slugging.

[0032] In some embodiments of this invention, the secondary cooling device 6 includes at least one of a shell cooling water circulation system and a phase change material (PCM) heat storage bag. The shell cooling water circulation system includes cooling pipes arranged around the shell of the secondary compressor 2 and a water pump that drives the cooling water to flow within the cooling pipes. The continuous flow of cooling water efficiently and stably removes the heat generated during compressor operation, thus suppressing excessively high exhaust temperatures at the source. The PCM heat storage bag absorbs heat from the secondary compressor 2 through contact heat transfer. The PCM absorbs a large amount of latent heat at a specific phase change temperature (such as the maximum allowable shell temperature of the compressor). When the compressor encounters sudden high loads, sudden changes in heat source, or other operating conditions that cause a sharp increase in heat generation, the PCM heat storage bag absorbs heat through phase change, smoothing the shell temperature fluctuations of the secondary compressor 2, preventing thermal shock, and providing a buffer time for the system to cope with fluctuating operating conditions.

[0033] This design provides active and efficient cooling through a shell cooling water circulation system and passive temperature buffering through a phase change material heat storage pack. The simultaneous application of both ensures that the secondary compressor always operates within a safe temperature range, thereby improving system reliability.

[0034] It should be understood that the focus of this utility model is to improve the structure of the steam heat pump system, and no special restrictions are placed on the control logic, etc.

[0035] The operation modes of the primary air supply device 5 and the secondary air supply device 6 described above can be designed according to actual needs. For example, such as... Figure 2 , 3 As shown, when the return gas superheat is below a certain range (e.g., 3~8℃), the gas supply of the first-stage gas supply device is adjusted, with the adjustment range being 10%-30% of the compressor displacement, to stabilize the evaporation pressure; when the compressor exhaust temperature exceeds a certain range (e.g., 95~105℃), the exhaust temperature is controlled below 100℃ through the second-stage cooling device.

[0036] like Figure 4 As shown, in order to achieve flexible configuration and scheduling of heat sources, the steam heat pump system also includes: a heat source delivery pipe and a switching device 7. The heat source delivery pipe exchanges heat with the evaporators in the evaporator group in sequence. The heat source delivery pipe first exchanges heat with the primary evaporator 3 and then with the secondary evaporator 4. The heat source delivery pipe is connected to different heat source input pipes (such as industrial wastewater, solar water heating, process waste heat or geothermal pipes) through the switching device 7 (such as an electric three-way valve or a multi-way valve group). This allows the system to select or combine the optimal heat source combination according to real-time operating conditions, heat source availability and cost-effectiveness.

[0037] Based on the switching design of the heat source pipeline, the preferred solution is that the heat source input pipeline includes at least two of the following: industrial hot water pipeline, air pipeline, and solar hot water pipeline. The industrial hot water pipeline is used to connect to the industrial wastewater heat source, the air pipeline is used to connect to the ambient air heat source, and the solar hot water pipeline is used to connect to the solar hot water heat source. This design integrates multiple heat sources, making the system more flexible, enhancing its adaptability to changing operating conditions, and improving its energy efficiency and economy.

[0038] The heat source switching method described above can be designed according to actual needs. For example, ... Figure 5 As shown, when the temperature of industrial wastewater reaches a certain range (e.g., 60~80℃), the system switches to the industrial hot water pipeline; when the ambient temperature reaches a certain range (e.g., 35~45℃), the system switches to the air pipeline; and when solar energy is sufficient (the outlet temperature of the collector reaches a certain range, e.g., 45~65℃), the system switches to the solar hot water pipeline to maximize the utilization of low-grade heat energy.

[0039] like Figure 6 As shown, in common applications of steam heat pump systems, these systems generate high-temperature steam for industrial use. The steam heat pump system also includes a steam ejector mixer 8, which can be a Venturi ejector with a throat diameter within a certain range (e.g., 20-30 mm). The steam ejector mixer 8 has a low-pressure inlet, a high-pressure inlet, and a steam outlet. The low-pressure inlet connects to the outlet of the evaporator assembly, and the high-pressure inlet connects to the exhaust port of the secondary compressor 2. The steam ejector mixer 8 utilizes the high-pressure exhaust from the secondary compressor 2 to eject the low-pressure steam output from the evaporator assembly, creating a mixing and pressurization effect. The steam outlet outputs the mixed steam, whose parameters must meet industrial requirements for delivery to the industrial process.

[0040] To optimize steam quality, an intercooler 9 and a steam generator 10 are installed between the exhaust port of the secondary compressor 2 and the high-pressure inlet of the steam ejector mixer 8. The intercooler 9 is located upstream of the steam generator 10 and can be a heat pipe heat exchanger. This design first uses the intercooler 9 to forcibly cool the high-temperature exhaust gas from the secondary compressor 2, reducing the exhaust temperature to a safe range to prevent overheating and damage to downstream equipment (such as the steam ejector mixer 8 or pipelines). After the high-temperature exhaust gas is cooled, the steam generator 10 uses the residual heat (e.g., through heat exchange) to generate additional steam or adjust the steam dryness, ensuring stable output steam conditions, improving steam quality, and meeting industrial application requirements.

[0041] In some embodiments of this utility model, the steam ejector mixer 8 also has a pressure regulating inlet, which is connected to an external gas supply station, allowing the introduction of external steam or gas when the internal pressure of the system fluctuates, quickly stabilizing the operating pressure inside the ejector mixer, and is especially suitable for variable working conditions, maintaining stable output through external gas source compensation.

[0042] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments according to this utility model. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings can be implemented in any order unless a specific express order is specified, and as long as the output of the preceding process is not used in the subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0043] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A steam heat pump system with a make-up gas bypass pipeline, including: An evaporator assembly, a primary compressor, and a secondary compressor are connected in sequence; characterized in that the primary compressor is equipped with a primary gas injection device, the primary gas injection device includes a flash evaporator, the flash evaporator is connected between the evaporator assembly and the suction port of the primary compressor through a gas injection bypass pipeline, and the secondary compressor is equipped with a secondary cooling device for cooling the casing.

2. The steam heat pump system according to claim 1, characterized in that, The evaporator assembly consists of a primary evaporator and a secondary evaporator. The refrigerant delivered from the primary evaporator is sent to the suction port of the primary compressor via the secondary evaporator. The inlet of the gas replenishment bypass pipeline is connected to the refrigerant pipeline between the primary evaporator and the secondary evaporator.

3. The steam heat pump system according to claim 2, characterized in that, The primary evaporator uses a shell-and-tube heat exchanger, and the secondary evaporator uses a microchannel heat exchanger.

4. The steam heat pump system according to claim 1, characterized in that, The primary gas supply device also includes a spiral guide plate, through which the refrigerant delivered by the flash evaporator is sent to the suction port of the primary compressor.

5. The steam heat pump system according to claim 1, characterized in that, The secondary cooling device includes: a shell cooling water circulation system and / or a phase change material heat storage bag that is in contact with the secondary compressor for heat transfer; The housing cooling water circulation system includes cooling pipes arranged around the housing of the secondary compressor and a water pump that drives the cooling water to flow within the cooling pipes.

6. The steam heat pump system according to claim 1, characterized in that, The steam heat pump system further includes a heat source delivery pipe for providing heat to the evaporator group, the heat source delivery pipe exchanging heat with the evaporators in the evaporator group successively, and the heat source delivery pipe being connected to the heat source input pipeline through a switching device.

7. The steam heat pump system according to claim 6, characterized in that, The heat source input pipeline includes at least two of the following: industrial hot water pipeline, air pipeline, and solar hot water pipeline; The industrial hot water pipeline is used to connect to an industrial wastewater heat source, the air pipeline is used to connect to an ambient air heat source, and the solar hot water pipeline is used to connect to a solar hot water heat source.

8. The steam heat pump system according to any one of claims 1 to 7, characterized in that, The steam heat pump system further includes a steam ejector mixer having a low-pressure inlet, a high-pressure inlet, and a steam outlet. The low-pressure inlet is connected to the outlet of the evaporator assembly, and the high-pressure inlet is connected to the exhaust port of the secondary compressor.

9. The steam heat pump system according to claim 8, characterized in that, An intercooler and a steam generator are provided between the exhaust port of the secondary compressor and the high-pressure inlet of the steam ejector mixer, with the intercooler located upstream of the steam generator.

10. The steam heat pump system according to claim 8, characterized in that, The steam ejector mixer also has a pressure regulating inlet, which is connected to an external gas supply station.

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