Multi-shaft multi-stage combined centrifugal heat pump system

Abstract

The invention relates to the technical field of heat pumps, in particular to a multi-shaft multi-stage combined centrifugal heat pump system which comprises a first centrifugal compressor unit and a second centrifugal compressor unit and further comprises a steam generator, a gas-liquid separator, a cooler and an evaporator. An inlet of the first centrifugal compressor unit is communicated with a gas-phase working medium outlet of the evaporator, an outlet of the first centrifugal compressor unit is communicated with a gas-phase working medium inlet of the steam generator, and a saturated steam outlet of the steam generator is sequentially connected with the gas-liquid separator and the second centrifugal compressor unit in series. A liquid phase working medium outlet of the steam generator is communicated with a liquid phase working medium inlet of the evaporator through the cooler, and the evaporator is communicated with a waste heat water conveying pipeline. High-temperature and high-quality superheated steam can be generated, the heat energy output upper limit temperature of a centrifugal heat pump unit is broken through, and use in more scenes is met.

Description

Technical Field

[0001] The invention relates to the technical field of heat pumps, and in particular to a multi-axis multi-stage combined centrifugal heat pump system. Background Art

[0002] Industrial heat pumps recycle waste heat from the process to achieve energy reuse, thereby improving energy efficiency and effectively reducing energy consumption and carbon emissions. Centrifugal heat pump units occupy an important position in the field of industrial heat pumps due to their outstanding features such as high heating temperature, large single unit capacity, wide range of waste heat utilization, diversified functions, high efficiency and energy saving.

[0003] At present, there is a great demand for heat in industrial park steam, industrial waste heat recovery, district heating, etc., which puts higher requirements on the upper temperature limit of heat output of heat pump units. Most of the existing centrifugal heat pump products can only provide hot water below 80°C or saturated steam at the corresponding pressure. However, in many industrial application scenarios, heat pumps are required to provide superheated high-temperature and high-pressure steam. Compared with saturated steam, superheated steam has high heat transfer efficiency and can improve energy utilization efficiency; at the same time, it reduces the generation of condensed water, can better maintain the dryness of the system, and is beneficial to some processes that are sensitive to moisture; and the energy loss of superheated steam is relatively small, and it can maintain a good state during pipeline transportation, which can be suitable for industrial application scenarios over longer distances.

[0004] Therefore, how to break through the upper limit of the thermal energy output of centrifugal heat pump units, realize the recovery of low-temperature waste heat sources below 30°C, and provide superheated steam above 100°C, so as to serve the waste heat recovery market more widely, promote the application of large and medium-sized centrifugal high-temperature heat pump units in energy conservation and consumption reduction, and low-carbon energy fields, and help the majority of industrial enterprises to develop low-carbon and high-quality development, has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a multi-axis multi-stage combined centrifugal heat pump system.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: The present invention provides a multi-axis multi-stage combined centrifugal heat pump system, comprising a first centrifugal compressor unit and a second centrifugal compressor unit, wherein the first centrifugal compressor unit comprises at least one first centrifugal compressor for compressing a gas-phase working medium, and the second centrifugal compressor unit comprises at least one second centrifugal compressor for pressurizing a saturated steam, and further comprises a steam generator, a gas-liquid separator, a cooler and an evaporator; the inlet of the first centrifugal compressor unit is connected to the gas-phase working medium outlet of the evaporator, the outlet of the first centrifugal compressor unit is connected to the gas-phase working medium inlet of the steam generator, the saturated steam outlet of the steam generator is connected in series with the gas-liquid separator and the second centrifugal compressor unit in sequence; the liquid-phase working medium outlet of the steam generator is connected to the liquid-phase working medium inlet of the evaporator through the cooler, and the evaporator is connected to a waste hot water delivery pipeline.

[0007] The multi-axis multi-stage combined centrifugal heat pump system provided by the present invention utilizes a first centrifugal compressor unit to compress a gaseous working medium, and transports the compressed gaseous working medium to a steam generator, where the compressed gaseous working medium exchanges heat with water to form saturated steam, and the saturated steam enters the second centrifugal compressor unit for secondary pressurization after gas-liquid separation to achieve further superheating of the saturated steam, thereby generating high-temperature and high-quality superheated steam. The temperature of the superheated steam can be as high as 140°C, breaking through the upper limit temperature of the thermal energy output of the centrifugal heat pump unit and meeting the use in more scenarios; by recycling and utilizing waste hot water resources, the conversion of liquid-phase working medium to gas-phase working medium is achieved, thereby ensuring the recycling of the working medium in the entire high-temperature heat pump system.

[0008] On the basis of the above technical solution, the present invention can also make the following improvements: Furthermore, the first centrifugal compressors in the first centrifugal compressor unit are connected in series in sequence, and the second centrifugal compressors in the second centrifugal compressor unit are connected in series in sequence.

[0009] The beneficial effect of adopting the above-mentioned further technical solution is that each first centrifugal compressor compresses the gas phase working medium in turn to increase the pressure and temperature of the gas phase working medium; each second centrifugal compressor pressurizes the saturated steam in turn to obtain high-temperature and high-quality superheated steam.

[0010] Furthermore, the first centrifugal compressor and the second centrifugal compressor are both controlled by a multi-shaft high-speed gearbox.

[0011] The beneficial effect of adopting the above-mentioned further technical solution is that the independent optimization design of the speeds of different high and low pressure stages is achieved through gearbox adjustment, ensuring the independent control of the speed of each stage of centrifugal compressor, thereby theoretically achieving the optimization of the stage efficiency, which is beneficial to improving the temperature, pressure and quality of superheated steam.

[0012] Furthermore, the first centrifugal compressor unit includes a first-stage centrifugal compressor, a second-stage centrifugal compressor, and a third-stage centrifugal compressor, and the second centrifugal compressor unit includes a fourth-stage centrifugal compressor.

[0013] The beneficial effect of adopting the above further technical solution is: by setting a three-stage series centrifugal compressor driven by a multi-axis high-speed gearbox, the gas phase working medium is compressed step by step to form a high-temperature and high-pressure gas phase working medium, which is beneficial to the heat exchange between the gas phase working medium and water in the steam generator, thereby forming saturated steam; the saturated steam is secondary pressurized by a four-stage centrifugal compressor to achieve further superheating of the saturated steam. The design of each pressure ratio in the multi-axis compression needs to change the speed, impeller diameter, etc. of each compressor according to different needs, so that the specific speed design point falls in the high-efficiency zone. Specifically, from the first-stage centrifugal compressor to the fourth-stage centrifugal compressor, the impeller diameter is gradually reduced, and the speed is gradually increased. It should be noted that the first centrifugal compressor and the second centrifugal compressor can be the same or different, as long as the speed can be increased step by step.

[0014] Furthermore, the multi-shaft high-speed gearbox includes a first transmission shaft and a second transmission shaft, the first-stage centrifugal compressor and the second-stage centrifugal compressor are driven by the first transmission shaft, and the third-stage centrifugal compressor and the fourth-stage centrifugal compressor are driven by the second transmission shaft.

[0015] The beneficial effect of adopting the above-mentioned further technical solution is: a two-shaft four-stage combined centrifugal compressor is adopted to reduce the volume of the compressor unit, and at the same time, different speeds of compressors at different stages can be achieved. The speed of each stage of compressor is independently designed to achieve theoretical optimization of stage efficiency, which can not only significantly improve the temperature and pressure of the outlet steam, but also ensure the quality of the steam, thereby meeting more extensive and stringent usage requirements.

[0016] Furthermore, it also includes a regenerator, which is arranged between the cooler and the evaporator and is used for supercooling the liquid phase working medium.

[0017] The beneficial effect of adopting the above-mentioned further technical solution is that after the liquid phase working medium - refrigerant enters the regenerator, it is cooled by the gas phase working medium at the outlet of the evaporator, thereby achieving further supercooling of the liquid phase working medium to form a supercooled liquid phase working medium, thereby improving the subsequent heat exchange efficiency of the supercooled liquid phase working medium in the evaporator.

[0018] Furthermore, the liquid-phase working medium inlet of the regenerator is connected to the outlet of the cooler, the supercooled liquid-phase working medium outlet of the regenerator is connected to the evaporator through a first pipeline, and an expansion valve is provided on the first pipeline; the gas-phase working medium outlet of the evaporator is connected to the gas-phase working medium inlet of the regenerator.

[0019] The beneficial effect of adopting the above-mentioned further technical scheme is that the supercooled liquid working fluid is throttled and depressurized by the expansion valve and enters the evaporator. In the evaporator, the working fluid absorbs the heat of the waste hot water, a low-temperature heat source, and is transformed into a gas. After that, the gaseous working fluid enters the regenerator and absorbs the heat of the liquid working fluid delivered from the cooler to achieve superheating of the gaseous working fluid. Subsequently, the gaseous working fluid enters the compressor, thereby completing the entire cycle process.

[0020] Furthermore, the cooler includes a first cooler and a second cooler, the first cooler is used to form a first supplementary gas phase working fluid and a liquid phase working fluid, the second cooler is used to form a second supplementary gas phase working fluid and a liquid phase working fluid, the first supplementary gas phase working fluid is transported to a three-stage centrifugal compressor, and the second supplementary gas phase working fluid is transported to a two-stage centrifugal compressor.

[0021] Furthermore, the first cooler includes a first tube side and a first shell side, and a first throttle valve is provided on the inlet pipeline of the first tube side; the second cooler includes a second tube side and a second shell side, and a second throttle valve is provided on the inlet pipeline of the second tube side.

[0022] The beneficial effect of adopting the above-mentioned further technical scheme is that: the first shell side contains high-temperature and high-pressure liquid-phase working medium from the steam generator, and the first tube side contains low-temperature two-phase working medium after throttling and reducing the pressure by the first throttle valve. The first throttle valve allows the high-temperature and high-pressure liquid-phase working medium-refrigerant to pass through at room temperature, and becomes a low-pressure and low-temperature liquid refrigerant, and produces a small amount of flash gas, thereby achieving the purpose of absorbing heat from the outside. After the high-temperature and high-pressure liquid-phase working medium and the low-temperature two-phase working medium exchange heat in the first cooler, the low-temperature two-phase working medium in the first tube side is heated to a saturated gas-phase working medium. The saturated gas-phase working medium enters the three-stage centrifugal compressor as the first supplementary gas-phase working medium for gas replenishment operation, and the liquid-phase working medium in the first shell side enters the second cooler. The above process is repeated to form a second supplementary gas-phase working medium. The second supplementary gas-phase working medium enters the two-stage centrifugal compressor for gas replenishment operation, and the liquid-phase working medium in the second shell side enters the regenerator or evaporator to form a gas-phase working medium again through heat exchange, thereby completing the entire cycle process.

[0023] Furthermore, the gas-liquid separator is connected to a water supply pipeline, and a water outlet of the gas-liquid separator is connected to a water inlet of the steam generator.

[0024] The beneficial effect of adopting the above-mentioned further technical solution is that: the water required for heat exchange with the high-temperature and high-pressure gas phase working medium in the steam generator is supplemented through the water supply pipeline to form saturated steam; after the water is transported to the gas-liquid separator through the water supply pipeline, it is mixed with the liquid after gas-liquid separation and enters the steam generator together for heat exchange.

[0025] Compared with the prior art, the present invention has the following technical effects: The multi-axis multi-stage combined centrifugal heat pump system provided by the present invention has centrifugal compressors at different stages playing different functional roles. The combined application of multi-axis multi-stage centrifugal compressors can not only significantly increase the temperature and pressure of outlet steam, but also ensure the quality of steam, thereby meeting more extensive and stringent usage requirements. The multi-axis high-speed gearbox technology is used to achieve independent optimization design of the speed of different high and low pressure stages through gearbox adjustment, ensuring independent control of the speed of each stage of centrifugal compressors, thereby achieving the optimization of stage efficiency in theory, which is beneficial to improving the temperature, pressure and quality of superheated steam; The gas phase working medium is compressed by the first three-stage centrifugal compressor and transported to the steam generator. The compressed gas phase working medium exchanges heat with water to form saturated steam. After gas-liquid separation, the saturated steam enters the four-stage centrifugal compressor for secondary pressurization to achieve further superheating of the saturated steam, thereby generating high-temperature and high-quality superheated steam. The temperature of the superheated steam can be as high as 140°C, breaking the upper limit temperature of the heat energy output of the centrifugal heat pump unit and meeting the use in more scenarios. By recycling the waste heat water resources, the conversion of liquid phase working fluid into gas phase working fluid is realized, ensuring the recycling of working fluid in the entire high temperature heat pump system; Through the setting of coolers and regenerators, the temperature of liquid working fluid can be reduced, which is beneficial to the heat exchange between the liquid working fluid and the low-temperature heat source in the evaporator, completing the conversion of liquid working fluid to gaseous working fluid, and realizing the recycling of the low-temperature waste water resource of 15-25℃; The setting of the cooler can generate gaseous working fluid while cooling the liquid working fluid, effectively performing air replenishment operation between stages of the centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram showing a two-shaft four-stage combined centrifugal heat pump system according to an embodiment of the present invention; Reference numerals: 1. Steam generator; 2. Gas-liquid separator; 3. Evaporator; 4. One-stage centrifugal compressor; 5. Two-stage centrifugal compressor; 6. Three-stage centrifugal compressor; 7. Four-stage centrifugal compressor; 8. Regenerator; 9. Expansion valve; 10. First cooler; 11. Second cooler; 12. First throttle valve; 13. Second throttle valve; 14. Waste hot water delivery pipeline; 15. First pipeline; 16. Water supply pipeline. DETAILED DESCRIPTION

[0027] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0028] Example See also Figure 1 , a two-axis four-stage combined centrifugal heat pump system, comprising a first centrifugal compressor unit and a second centrifugal compressor unit, the first centrifugal compressor unit comprising a first-stage centrifugal compressor 4, a second-stage centrifugal compressor 5, and a third-stage centrifugal compressor 6, the second centrifugal compressor unit comprising a fourth-stage centrifugal compressor 7, and also comprising a steam generator 1, a gas-liquid separator 2, a first cooler 10, a second cooler 11, an evaporator 3 and a regenerator 8; the first-stage centrifugal compressor 4, the second-stage centrifugal compressor 5, and the third-stage centrifugal compressor 6 are sequentially connected in series for compressing a gas phase working medium, the fourth-stage centrifugal compressor 7 is used for pressurizing saturated steam to achieve further superheating of the saturated steam to obtain high-temperature and high-quality superheated steam, the high-temperature and high-quality superheated steam having a stable pressure, no fluctuation, a low water content or no water, and the superheated steam has a high cleanliness and a low impurity content; the first-stage centrifugal compressor 4 The gaseous working medium is communicated with the gaseous working medium outlet of the evaporator 3, the outlet of the three-stage centrifugal compressor 6 is communicated with the gaseous working medium inlet of the steam generator 1, the saturated steam outlet of the steam generator 1 is connected in series with the gas-liquid separator 2 and the four-stage centrifugal compressor 7 in sequence, the gaseous working medium flows through the first-stage centrifugal compressor 4, the second-stage centrifugal compressor 5, and the third-stage centrifugal compressor 6 through the gas-phase working medium outlet of the evaporator 3 through a pipeline and is compressed step by step to form a high-temperature and high-pressure gaseous working medium, the high-temperature and high-pressure gaseous working medium is transported into the steam generator 1 through a pipeline to exchange heat with water, the water absorbs the heat of the high-temperature and high-pressure gaseous working medium to generate saturated steam, the saturated steam carries liquid, the saturated steam is transported to the gas-liquid separator 2 through a pipeline, after the gas-liquid separation treatment, the saturated steam without liquid is transported to the four-stage centrifugal compressor 7 through a pipeline for pressurization and superheating treatment, so as to achieve further superheating of the saturated steam and form the required high-temperature and high-quality superheated steam.

[0029] Among them, the first-stage centrifugal compressor 4, the second-stage centrifugal compressor 5, the third-stage centrifugal compressor 6, and the fourth-stage centrifugal compressor 7 are controlled by a multi-axis high-speed gearbox to set different speeds of each stage of the compressor according to the compression requirements. The multi-axis high-speed gearbox includes a first transmission shaft and a second transmission shaft. The first-stage centrifugal compressor 4 and the second-stage centrifugal compressor 5 are driven by the first transmission shaft, and the third-stage centrifugal compressor 6 and the fourth-stage centrifugal compressor 7 are driven by the second transmission shaft.

[0030] The liquid-phase working medium outlet of the steam generator 1 is connected to the liquid-phase working medium inlets of the first cooler 10, the second cooler 11, the regenerator 8, and the evaporator 3 in sequence, and the evaporator 3 is connected to the waste hot water delivery pipeline 14 to realize the conversion of the liquid-phase working medium into the gas-phase working medium. Specifically, the high-temperature and high-pressure gas-phase working medium exchanges heat with water in the steam generator 1, and the high-temperature and high-pressure gas-phase working medium condenses into a high-temperature and high-pressure liquid-phase working medium. The high-temperature and high-pressure liquid-phase working medium is transported to the first cooler 10, the second cooler 11, the regenerator 8, and the evaporator 3 in sequence through the liquid-phase working medium outlet and pipeline of the steam generator 1 to complete the conversion into the gas-phase working medium.

[0031] The first cooler 10 includes a first tube side and a first shell side, and a first throttle valve 12 is provided on the inlet pipeline of the first tube side. The first cooler 10 is used to form a first supplementary gas-phase working medium and a liquid-phase working medium, and the first supplementary gas-phase working medium is transported to the three-stage centrifugal compressor 6 for supplementing the gas-phase working medium; the second cooler 11 includes a second tube side and a second shell side, and a second throttle valve 13 is provided on the inlet pipeline of the second tube side. The second cooler 11 is used to form a second supplementary gas-phase working medium and a liquid-phase working medium, and the second supplementary gas-phase working medium is transported to the two-stage centrifugal compressor 5 for gas replenishment operation.

[0032] After being transported through the pipeline, the high-temperature and high-pressure liquid-phase working medium is divided into two parts, one of which enters the first shell side of the first cooler 10, and the other part is throttled by the first throttle valve 12 to form a low-temperature two-phase working medium and then enters the first tube side of the first cooler 10. The two parts of working medium with different temperatures and pressures exchange heat in the first cooler 10. Specifically, the low-temperature two-phase working medium in the first tube side absorbs the heat of the liquid-phase working medium in the first shell side and becomes a saturated gas-phase working medium. This part of the saturated gas-phase working medium enters the three-stage centrifugal compressor 6 for inter-stage air replenishment operation; and the liquid-phase working medium in the first shell side is transported through the pipeline and is divided into two parts again, one of which enters In the second shell side of the second cooler 11, the other part is formed into a low-temperature two-phase working fluid through the throttling action of the second throttle valve 13 and then enters the second pipe side of the second cooler 11. The two parts of working fluid with different temperatures and pressures exchange heat in the second cooler 11. Specifically, the low-temperature two-phase working fluid in the second pipe side absorbs the heat of the liquid-phase working fluid in the second shell side and becomes a saturated gas-phase working fluid. This part of the saturated gas-phase working fluid enters the secondary centrifugal compressor 5 for inter-stage air replenishment operation, and the liquid-phase working fluid in the second shell side enters the regenerator 8 through the pipeline to achieve further supercooling to form a supercooled liquid-phase working fluid, which is convenient for subsequent heat exchange with the low-temperature heat source and improves the heat exchange efficiency.

[0033] The liquid phase working medium inlet of the regenerator 8 is communicated with the outlet of the second cooler 11, the supercooled liquid phase working medium outlet of the regenerator 8 is communicated with the evaporator 3 through the first pipeline 15, and the first pipeline 15 is provided with an expansion valve 9, the gas phase working medium outlet of the evaporator 3 is communicated with the gas phase working medium inlet of the regenerator 8, the inlet of the evaporator 3 is connected to the waste hot water delivery pipeline 14, the supercooled liquid phase working medium enters the evaporator 3 through the first pipeline 15, and the supercooled liquid phase working medium enters the evaporator 3 after the throttling and pressure reduction treatment of the expansion valve 9, and the evaporator 3 is heated to 400 ℃. In the process, the supercooled liquid working medium exchanges heat with the waste hot water delivered via the waste hot water delivery pipeline 14, and the supercooled liquid working medium absorbs the heat of the waste hot water and is converted into a gaseous state, completing the conversion of the liquid working medium into the gaseous working medium. After that, the gaseous working medium enters the regenerator 8, and exchanges heat with the liquid working medium delivered via the second shell side of the second cooler 11, that is, the gaseous working medium supercools the liquid working medium, thereby forming a supercooled liquid working medium, and the gaseous working medium absorbs heat and rises in temperature before entering the first-stage centrifugal compressor 4 through the pipeline, thereby completing the entire cycle process.

[0034] The gas-liquid separator 2 is connected to the water supply pipe 16, and the water outlet of the gas-liquid separator 2 is connected to the water inlet of the steam generator 1. The water required for heat exchange with the high-temperature and high-pressure gas phase working medium in the steam generator 1 is supplemented through the water supply pipe 16 to form saturated steam; after the softened water is transported to the gas-liquid separator 2 through the water supply pipe 16, it is mixed with the saturated water after gas-liquid separation and then enters the steam generator 1 for heat exchange. The water supply is softened water to reduce the generation of scale in the steam generator 1.

[0035] The steam generator 1 and the gas-liquid separator 2 adopt the microgravity high-efficiency steam generation and separation integrated device in the Chinese invention patent application with application number CN202310988640.7. By integrating the water vapor generation and gas-liquid separation functions together, the overall process of the heat pump unit is simplified, making the unit more simple and efficient.

[0036] The multi-axis multi-stage combined centrifugal heat pump system provided by the present invention compresses the gas phase working medium through the first-stage centrifugal compressor 4, the second-stage centrifugal compressor 5, and the third-stage centrifugal compressor 6 to obtain a high-temperature and high-pressure gas phase working medium, and transports the high-temperature and high-pressure gas phase working medium to the microgravity high-efficiency steam generation and separation integrated device to obtain saturated steam, and then uses the fourth-stage centrifugal compressor 7 to pressurize and superheat the saturated steam to achieve further superheating of the saturated steam, thereby producing high-temperature and high-quality superheated steam, the temperature of which can reach 140°C, which can not only significantly improve the temperature and pressure of the steam at the system outlet, but also ensure the quality of the steam, thereby meeting more extensive and stringent usage requirements.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-axis multi-stage combined centrifugal heat pump system, characterized in that: The invention comprises a first centrifugal compressor unit and a second centrifugal compressor unit, wherein the first centrifugal compressor unit comprises at least one first centrifugal compressor for compressing a gas phase working medium, and the second centrifugal compressor unit comprises at least one second centrifugal compressor for pressurizing a saturated steam, and further comprises a steam generator (1), a gas-liquid separator (2), a cooler and an evaporator (3); the inlet of the first centrifugal compressor unit is connected to the gas phase working medium outlet of the evaporator (3), the outlet of the first centrifugal compressor unit is connected to the gas phase working medium inlet of the steam generator (1), the saturated steam outlet of the steam generator (1) is connected in series with the gas-liquid separator (2) and the second centrifugal compressor unit in sequence; the liquid phase working medium outlet of the steam generator (1) is connected to the liquid phase working medium inlet of the evaporator (3) through the cooler, and the evaporator (3) is connected to a waste hot water delivery pipeline (14).

2. The multi-axis multi-stage combined centrifugal heat pump system according to claim 1, characterized in that: The first centrifugal compressors in the first centrifugal compressor unit are connected in series in sequence, and the second centrifugal compressors in the second centrifugal compressor unit are connected in series in sequence.

3. The multi-axis multi-stage combined centrifugal heat pump system according to claim 2, characterized in that: The first centrifugal compressor and the second centrifugal compressor are both driven and controlled by a multi-shaft high-speed gearbox.

4. The multi-axis multi-stage combined centrifugal heat pump system according to claim 3, characterized in that: The first centrifugal compressor unit comprises a first-stage centrifugal compressor (4), a second-stage centrifugal compressor (5), and a third-stage centrifugal compressor (6), and the second centrifugal compressor unit comprises a fourth-stage centrifugal compressor (7).

5. The multi-axis multi-stage combined centrifugal heat pump system according to claim 4, characterized in that: The multi-shaft high-speed gearbox comprises a first transmission shaft and a second transmission shaft, the first-stage centrifugal compressor (4) and the second-stage centrifugal compressor (5) are driven by the first transmission shaft, and the third-stage centrifugal compressor (6) and the fourth-stage centrifugal compressor (7) are driven by the second transmission shaft.

6. The multi-axis multi-stage combined centrifugal heat pump system according to any one of claims 1 to 5, characterized in that: It also comprises a regenerator (8), which is arranged between the cooler and the evaporator (3) and is used for supercooling the liquid phase working medium.

7. The multi-axis multi-stage combined centrifugal heat pump system according to claim 6, characterized in that: The liquid phase working medium inlet of the regenerator (8) is connected to the outlet of the cooler, the subcooled liquid phase working medium outlet of the regenerator (8) is connected to the evaporator (3) via a first pipeline (15), and an expansion valve (9) is provided on the first pipeline (15); the gas phase working medium outlet of the evaporator (3) is connected to the gas phase working medium inlet of the regenerator (8).

8. The multi-axis multi-stage combined centrifugal heat pump system according to claim 4, characterized in that: The cooler comprises a first cooler (10) and a second cooler (11); the first cooler (10) is used to form a first supplementary gas phase working medium and a liquid phase working medium; the second cooler (11) is used to form a second supplementary gas phase working medium and a liquid phase working medium; the first supplementary gas phase working medium is transported to the three-stage centrifugal compressor (6); and the second supplementary gas phase working medium is transported to the two-stage centrifugal compressor (5).

9. The multi-axis multi-stage combined centrifugal heat pump system according to claim 8, characterized in that: The first cooler (10) comprises a first tube side and a first shell side, and a first throttle valve (12) is provided on the inlet pipeline of the first tube side; the second cooler (11) comprises a second tube side and a second shell side, and a second throttle valve (13) is provided on the inlet pipeline of the second tube side.

10. The multi-axis multi-stage combined centrifugal heat pump system according to claim 1, characterized in that: The gas-liquid separator (2) is connected to a water supply pipeline (16), and a water outlet of the gas-liquid separator (2) is connected to a water inlet of the steam generator (1).

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