Supercritical CO2 rotating machinery shaft seal leakage test system and back pressure control method

Abstract

The invention relates to the technical field of power machinery, and provides a supercritical CO2 rotating machinery shaft seal leakage test system and a backpressure control method. The supercritical CO2 rotating machinery shaft seal leakage test system comprises a compressor, a heat source, a turbine, a cooler, a first backpressure adjusting storage tank and a second backpressure adjusting storage tank. A compressor shaft seal outlet of the compressor is connected with the first backpressure adjusting storage tank, a turbine shaft seal outlet of the turbine is connected with the second backpressure adjusting storage tank, a first backpressure valve is arranged at the outlet end of the first backpressure adjusting storage tank, and a second backpressure valve is arranged at the outlet end of the second backpressure adjusting storage tank. According to the supercritical CO2 rotating machinery shaft seal leakage test system and the back pressure control method, the defects that an existing rotating machinery shaft seal leakage characteristic test device cannot achieve sustainable operation of the leakage characteristic test process and is only suitable for conventional steam and air working medium rotating machinery application scenes are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of power machinery, and in particular to a supercritical CO2 rotating machinery shaft seal leakage test system and a back pressure control method. Background Art

[0002] Supercritical carbon dioxide rotating machinery is the core equipment of supercritical carbon dioxide cycle power generation system. When high-temperature and high-pressure supercritical carbon dioxide enters high-speed supercritical carbon dioxide rotating machinery, it will inevitably leak through the shaft seal channel. The leakage characteristics of the shaft seal have a decisive influence on the system cycle efficiency and operation stability. Experimental research is an indispensable key link in the transformation of supercritical carbon dioxide Brayton cycle system from theoretical research to practical application. The harsh operating conditions and physical properties that seriously deviate from the physical properties of ideal gas have posed new challenges to the leakage characteristics test device of the shaft seal under the supercritical carbon dioxide operating environment.

[0003] In the existing steam Rankine cycle system and air Brayton cycle system, the leakage outlet back pressure of the rotary machinery shaft seal leakage characteristic test device is generally atmospheric pressure, and it is directly discharged into the environment. However, the solution of direct atmospheric back pressure discharge adopted by the test device for rotary machinery shaft seal leakage characteristic is only applicable to the application scenarios of rotary machinery with conventional steam and air working fluids. If it is applied to supercritical carbon dioxide rotary machinery, it is difficult to carry out experimental research on the influence of back pressure changes on leakage characteristics. In addition, the direct discharge of the leaking working fluid will cause the working fluid of the circulation system to continue to decrease, which is not conducive to the sustainable operation of the leakage characteristic test process. Summary of the invention

[0004] The present invention provides a supercritical CO2 rotating machinery shaft seal leakage test system and a back pressure control method, which are used to solve the defect that the existing test device for the leakage characteristics of the rotating machinery shaft seal cannot achieve sustainable operation of the leakage characteristics test process and is only applicable to the application scenarios of conventional steam and air working medium rotating machinery.

[0005] On the one hand, the present invention provides a supercritical CO2 rotating machinery shaft seal leakage test system, comprising: a compressor, a heat source, a turbine, a cooler, a first back pressure regulating tank and a second back pressure regulating tank; the outlet end of the compressor is connected to the inlet end of the heat source, the outlet end of the heat source is connected to the inlet end of the turbine, the outlet end of the turbine is connected to the inlet end of the cooler, and the outlet end of the cooler is connected to the inlet end of the compressor; the compressor shaft seal outlet of the compressor is connected to the first back pressure regulating tank, the turbine shaft seal outlet of the turbine is connected to the second back pressure regulating tank, the outlet end of the first back pressure regulating tank is provided with a first back pressure valve, and the outlet end of the second back pressure regulating tank is provided with a second back pressure valve.

[0006] According to the supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention, a first pressure sensor and a first flow sensor are provided on the pipeline connecting the compressor shaft seal outlet and the first back pressure regulating tank.

[0007] According to the supercritical CO2 rotating machinery shaft seal leakage test system provided by the present invention, a second pressure sensor and a second flow sensor are provided on the pipeline connecting the turbine shaft seal outlet and the second back pressure regulating tank.

[0008] According to the supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention, a first stop valve is provided on the pipeline connecting the compressor shaft seal outlet and the first back pressure regulating tank.

[0009] According to the supercritical CO2 rotating machinery shaft seal leakage test system provided by the present invention, a second stop valve is provided on the pipeline connecting the turbine shaft seal outlet and the second back pressure regulating tank.

[0010] The supercritical CO2 rotary machinery shaft seal leakage test system provided according to the present invention also includes a working fluid recovery unit, the outlet ends of the first back pressure regulating tank and the second back pressure regulating tank are both connected to the inlet end of the working fluid recovery unit, and the outlet end of the working fluid recovery unit is connected to the inlet end of the compressor.

[0011] According to the supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention, the working fluid recovery unit includes a liquefier, a liquid storage tank, a gas storage tank and a heater connected in sequence, the outlet ends of the first back pressure regulating tank and the second back pressure regulating tank are both connected to the inlet end of the liquefier, and the outlet end of the heater is connected to the inlet end of the compressor.

[0012] According to the supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention, a regulating valve is provided at the inlet end of the liquefier; and / or a throttle valve is provided on the pipeline connecting the liquid storage tank and the gas storage tank; and / or a third stop valve is provided on the pipeline connecting the heater and the compressor; and / or a booster pump is provided at the outlet end of the liquefier.

[0013] According to the supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention, a third back pressure valve is provided on the pipeline connecting the gas storage tank and the heater.

[0014] Another aspect of the present invention provides a back pressure control method for a supercritical CO2 rotating machinery shaft seal leakage test system based on any one of the above items, comprising the following steps.

[0015] The first pressure data and the first flow data of the compressor shaft seal outlet are obtained, and the second pressure data and the second flow data of the turbine shaft seal outlet are obtained.

[0016] The shaft seal leakage of the compressor under a set back pressure is determined based on the first pressure data and the first flow data, and the shaft seal leakage of the turbine under a set back pressure is determined based on the second pressure data and the second flow data.

[0017] The opening of the first back-pressure valve is determined based on the shaft seal leakage of the compressor under the set back pressure, and the opening of the second back-pressure valve is determined based on the shaft seal leakage of the turbine under the set back pressure.

[0018] The supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention can make the compressor shaft seal outlet and the turbine shaft seal outlet be respectively placed under corresponding back pressure conditions by connecting a first back pressure regulating storage tank to the compressor shaft seal outlet of the compressor, connecting a second back pressure regulating storage tank to the turbine shaft seal outlet of the turbine, and respectively arranging a first back pressure valve and a second back pressure valve at the outlet end of the first back pressure regulating storage tank and the outlet end of the second back pressure regulating storage tank, thereby effectively solving the problem that the traditional rotary machinery shaft seal leakage characteristic test scheme is difficult to meet the requirements of continuously and stably carrying out the supercritical carbon dioxide rotary machinery shaft seal leakage characteristic test. In addition, since the first back pressure valve and the second back pressure valve are independent of each other, the compressor shaft seal leakage and the turbine shaft seal leakage under different back pressure conditions can be measured simultaneously, thereby achieving high efficiency and flexibility in the test.

[0019] The back pressure control method provided by the present invention obtains the first pressure data and the first flow data of the compressor shaft seal outlet, the second pressure data and the second flow data of the turbine shaft seal outlet, and determines the compressor shaft seal leakage under the set back pressure condition according to the first pressure data and the first flow data, determines the turbine shaft seal leakage under the set back pressure condition according to the second pressure data and the second flow data, and finally determines the opening of the first back pressure valve according to the compressor shaft seal leakage under the set back pressure condition, and determines the opening of the second back pressure valve based on the turbine shaft seal leakage under the set back pressure condition. The method can realize adaptive adjustment of the openings of the first back pressure valve and the second back pressure valve, and through repeated tests for multiple times, can obtain the compressor and turbine shaft seal leakage test results under multiple groups of back pressure conditions.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of a supercritical CO2 rotary mechanical shaft seal leakage test system provided in an embodiment of the present invention.

[0023] Figure 2 It is a flow chart of the back pressure control method provided by an embodiment of the present invention.

[0024] Reference numerals: 1. Compressor; 101. Compressor shaft seal outlet; 2. Heat source; 3. Turbine; 301. Turbine shaft seal outlet; 4. Cooler; 5. First back pressure regulating tank; 6. Second back pressure regulating tank; 7. First back pressure valve; 8. Second back pressure valve; 9. First pressure sensor; 10. First flow sensor; 11. Second pressure sensor; 12. Second flow sensor; 13. First stop valve; 14. Second stop valve; 15. Liquefier; 16. Liquid storage tank; 17. Gas storage tank; 18. Heater; 19. Control valve; 20. Throttle valve; 21. Third stop valve; 22. Booster pump; 23. Third back pressure valve. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] Combine the following Figure 1 and Figure 2 The invention describes a supercritical CO2 rotary machinery shaft seal leakage test system and a back pressure control method.

[0031] See also Figure 1 As shown, the supercritical CO2 rotating machinery shaft seal leakage test system provided in an embodiment of the present invention includes: a compressor 1, a heat source 2, a turbine 3, a cooler 4, a first back pressure regulating tank 5 and a second back pressure regulating tank 6.

[0032] Among them, the outlet end of the compressor 1 is connected to the inlet end of the heat source 2, the outlet end of the heat source 2 is connected to the inlet end of the turbine 3, the outlet end of the turbine 3 is connected to the inlet end of the cooler 4, and the outlet end of the cooler 4 is connected to the inlet end of the compressor 1; the compressor shaft seal outlet 101 of the compressor 1 is connected to the first back pressure regulating tank 5, the turbine shaft seal outlet 301 of the turbine 3 is connected to the second back pressure regulating tank 6, the outlet end of the first back pressure regulating tank 5 is provided with a first back pressure valve 7, and the outlet end of the second back pressure regulating tank 6 is provided with a second back pressure valve 8.

[0033] The supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention can make the compressor shaft seal outlet 101 and the turbine shaft seal outlet 301 of the turbine 3 be in corresponding back pressure conditions by connecting the first back pressure regulating storage tank 5 to the compressor shaft seal outlet 101 of the compressor 1, connecting the second back pressure regulating storage tank 6 to the turbine shaft seal outlet 301 of the turbine 3, and respectively arranging the first back pressure valve 7 and the second back pressure valve 8 at the outlet end of the first back pressure regulating storage tank 5 and the outlet end of the second back pressure regulating storage tank 6, so as to effectively solve the problem that the traditional rotary machinery shaft seal leakage characteristic test scheme is difficult to meet the requirements of the continuous and stable supercritical carbon dioxide rotary machinery shaft seal leakage characteristic test. In addition, since the first back pressure valve 7 and the second back pressure valve 8 are independent of each other, the compressor 1 shaft seal leakage and the turbine 3 shaft seal leakage under different back pressure conditions can be measured simultaneously, so as to achieve high efficiency and flexibility of the test.

[0034] Specifically, during the test, the carbon dioxide working medium leaked from the compressor shaft seal outlet 101 enters the first back pressure regulating storage tank 5 through the pipe section, and the pressure in the tank is maintained constant by the first back pressure valve 7 provided on the outlet pipe section of the first back pressure regulating storage tank 5, providing a constant back pressure condition for the supercritical carbon dioxide compressor shaft seal outlet 101. Similarly, during the test, the carbon dioxide working medium leaked from the turbine shaft seal outlet 301 enters the second back pressure regulating storage tank 6 through the pipe section, and the pressure in the tank is maintained constant by the second back pressure valve 8 provided on the outlet pipe section of the second back pressure regulating storage tank 6, providing a constant back pressure condition for the supercritical carbon dioxide turbine shaft seal outlet 301.

[0035] See also Figure 1 As shown, according to some embodiments of the present invention, a first pressure sensor 9 and a first flow sensor 10 are provided on the pipeline connecting the compressor shaft seal outlet 101 and the first back pressure regulating storage tank 5. By providing the first pressure sensor 9 and the first flow sensor 10 on the pipeline connecting the compressor shaft seal outlet 101 and the first back pressure regulating storage tank 5, the pressure data and flow data of the compressor shaft seal outlet 101 can be obtained, and then the shaft seal leakage of the compressor 1 under the set back pressure can be determined, and finally the opening of the first back pressure valve 7 (specifically, the position of the spring push rod of the first back pressure valve 7) is adjusted to adjust the pressure in the first back pressure regulating storage tank 5.

[0036] See also Figure 1 As shown, according to some embodiments of the present invention, a second pressure sensor 11 and a second flow sensor 12 are provided on the pipeline connecting the turbine shaft seal outlet 301 and the second back pressure regulating storage tank 6. By providing the second pressure sensor 11 and the second flow sensor 12 on the pipeline connecting the turbine shaft seal outlet 301 and the second back pressure regulating storage tank 6, the pressure data and flow data of the turbine shaft seal outlet 301 can be obtained, and then the shaft seal leakage of the turbine 3 under the set back pressure can be determined, and finally the opening of the second back pressure valve 8 (specifically, the position of the spring push rod of the second back pressure valve 8) can be adjusted to adjust the pressure in the second back pressure regulating storage tank 6.

[0037] See also Figure 1 As shown, according to some embodiments of the present invention, a first stop valve 13 is provided on the pipeline connecting the compressor shaft seal outlet 101 and the first back pressure regulating storage tank 5. By providing the first stop valve 13 on the pipeline connecting the compressor shaft seal outlet 101 and the first back pressure regulating storage tank 5, when the system is not working, the connection between the compressor shaft seal outlet 101 and the first back pressure regulating storage tank 5 can be isolated by the first stop valve 13.

[0038] See also Figure 1 As shown, according to some embodiments of the present invention, a second stop valve 14 is provided on the pipeline connecting the turbine shaft seal outlet 301 and the second back pressure regulating storage tank 6. By providing the second stop valve 14 on the pipeline connecting the turbine shaft seal outlet 301 and the second back pressure regulating storage tank 6, when the system is not working, the connection between the turbine shaft seal outlet 301 and the second back pressure regulating storage tank 6 can be isolated by the second stop valve 14.

[0039] See also Figure 1 As shown, according to some embodiments of the present invention, the supercritical CO2 rotary machinery shaft seal leakage test system further includes a working fluid recovery unit, and the outlet ends of the first back pressure regulating storage tank 5 and the second back pressure regulating storage tank 6 are both connected to the inlet end of the working fluid recovery unit, and the outlet end of the working fluid recovery unit is connected to the inlet end of the compressor 1. By providing the working fluid recovery unit, the working fluid gas leaked through the compressor shaft seal outlet 101 and the turbine shaft seal outlet 301 can be reintroduced into the compressor 1 through the working fluid recovery unit and continue to circulate in the system. Compared with the direct discharge solution in the prior art, it can effectively avoid the leakage loss of the circulating system working fluid, maintain the stable operation of the test system, and make the test process efficient and reliable.

[0040] See also Figure 1As shown, according to some embodiments of the present invention, the working fluid recovery unit includes a liquefier 15, a liquid storage tank 16, a gas storage tank 17 and a heater 18 connected in sequence, the outlet ends of the first back pressure regulating tank 5 and the second back pressure regulating tank 6 are both connected to the inlet end of the liquefier 15, and the outlet end of the heater 18 is connected to the inlet end of the compressor 1.

[0041] Specifically, during the test, the outlet working fluid of the first back pressure valve 7 and the outlet working fluid of the second back pressure valve 8 are collected and enter the liquefier 15 for liquefaction, and the liquefied liquid carbon dioxide working fluid then enters the liquid storage tank 16 for storage, and after throttling and reducing the pressure through the throttle valve 20 at the outlet of the liquid storage tank 16, the liquid carbon dioxide working fluid is converted into gaseous carbon dioxide working fluid, and the gaseous carbon dioxide working fluid enters the gas storage tank 17 for storage, and then enters the heater 18 for heating, so that the working fluid temperature at the outlet of the heater 18 reaches the inlet temperature of the compressor 1. Driven by the pressure difference, the working fluid leaking from the shaft seal re-enters the circulation system, realizing the recycling of the leaked working fluid during the test.

[0042] See also Figure 1 As shown, according to some embodiments of the present invention, a regulating valve 19 is provided at the inlet end of the liquefier 15. By providing the regulating valve 19 at the inlet end of the liquefier 15, the flow rate and pressure of the gaseous medium entering the liquefier 15 can be controlled by controlling the opening of the regulating valve 19.

[0043] See also Figure 1 As shown, according to some embodiments of the present invention, a throttle valve 20 is provided on the pipeline connecting the liquid storage tank 16 and the gas storage tank 17. By providing the throttle valve 20 on the pipeline connecting the liquid storage tank 16 and the gas storage tank 17, the liquid carbon dioxide working medium can be throttled and depressurized to be converted into gaseous carbon dioxide working medium.

[0044] See also Figure 1 As shown, according to some embodiments of the present invention, a third stop valve 21 is provided on the pipeline connecting the heater 18 and the compressor 1. By providing the third stop valve 21 on the pipeline connecting the heater 18 and the compressor 1, when the system is not working, the connection between the heater 18 and the compressor 1 can be isolated by the third stop valve 21.

[0045] See also Figure 1 As shown, according to some embodiments of the present invention, a booster pump 22 is provided at the outlet of the liquefier 15. By providing the booster pump 22 at the outlet of the liquefier 15, the liquid carbon dioxide working medium can be pressurized to a set pressure, and the pressurized liquid carbon dioxide working medium then enters the liquid storage tank 16 for storage.

[0046] See also Figure 1As shown, according to some embodiments of the present invention, a third back pressure valve 23 is provided on the pipeline connecting the gas storage tank 17 and the heater 18. By providing the third back pressure valve 23 on the pipeline connecting the gas storage tank 17 and the heater 18, the working medium pressure in the gas storage tank 17 can be maintained at a pressure slightly higher than the inlet pipe section of the supercritical compressor 1.

[0047] The back pressure control method provided by the present invention is described below. The back pressure control method provided by the present invention and the above-mentioned supercritical CO2 rotary mechanical shaft seal leakage test system can be referred to each other.

[0048] See also Figure 2 As shown, the back pressure control method provided in the embodiment of the present invention is implemented based on the supercritical CO2 rotating machinery shaft seal leakage test system as described in any of the above embodiments, and includes the following steps.

[0049] S210 , obtaining first pressure data and first flow data of the compressor shaft seal outlet 101 , and obtaining second pressure data and second flow data of the turbine shaft seal outlet 301 .

[0050] S220. Determine the shaft seal leakage of compressor 1 under a set back pressure based on the first pressure data and the first flow data, and determine the shaft seal leakage of turbine 3 under a set back pressure based on the second pressure data and the second flow data.

[0051] S230. Determine the opening of the first back pressure valve 7 based on the shaft seal leakage of the compressor 1 under the set back pressure, and determine the opening of the second back pressure valve 8 based on the shaft seal leakage of the turbine 3 under the set back pressure.

[0052] The back pressure control method provided by the present invention obtains the first pressure data and the first flow data of the compressor shaft seal outlet 101, the second pressure data and the second flow data of the turbine shaft seal outlet 301, and determines the shaft seal leakage of the compressor 1 under the set back pressure condition according to the first pressure data and the first flow data, determines the shaft seal leakage of the turbine 3 under the set back pressure condition according to the second pressure data and the second flow data, and finally determines the opening of the first back pressure valve 7 according to the shaft seal leakage of the compressor 1 under the set back pressure condition, and determines the opening of the second back pressure valve 8 based on the shaft seal leakage of the turbine 3 under the set back pressure condition. It can realize adaptive adjustment of the openings of the first back pressure valve 7 and the second back pressure valve 8, and through repeated tests for multiple times, it can obtain the test results of the shaft seal leakage of the compressor 1 and the turbine 3 under multiple groups of back pressure conditions.

[0053] Specifically, in step S210, the first pressure data and the first flow data of the compressor shaft seal outlet 101 are obtained through the first pressure sensor 9 and the first flow sensor 10 respectively; the second pressure data and the second flow data of the turbine shaft seal outlet 301 are obtained through the second pressure sensor 11 and the second flow sensor 12 respectively.

[0054] In step S220, on the premise that the first pressure data and the first flow data are obtained, the ideal gas state equation or other appropriate fluid dynamics equations can be used to estimate the shaft seal leakage of the compressor 1 under the set back pressure condition; similarly, on the premise that the second pressure data and the second flow data are obtained, the ideal gas state equation or other appropriate fluid dynamics equations can be used to estimate the shaft seal leakage of the turbine 3 under the set back pressure condition.

[0055] In step S230, the opening of the corresponding back-pressure valve can be adjusted by adjusting the position of the spring push rods of the first back-pressure valve 7 and the second back-pressure valve 8, thereby adjusting the pressure in the corresponding back-pressure regulating tank.

[0056] From the description of the above implementation modes, it can be seen that the supercritical CO2 rotating machinery shaft seal leakage test system and back pressure control method provided by the present invention have at least the following advantages.

[0057] (1) The supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention can make the compressor shaft seal outlet 101 and the turbine shaft seal outlet 301 of the turbine 3 be under corresponding back pressure conditions by connecting the first back pressure regulating storage tank 5 to the compressor shaft seal outlet 101 of the compressor 1, connecting the second back pressure regulating storage tank 6 to the turbine shaft seal outlet 301 of the turbine 3, and respectively arranging the first back pressure valve 7 and the second back pressure valve 8 at the outlet end of the first back pressure regulating storage tank 5 and the outlet end of the second back pressure regulating storage tank 6, so as to effectively solve the problem that the traditional rotary machinery shaft seal leakage characteristic test scheme is difficult to meet the requirements of the continuous and stable supercritical carbon dioxide rotary machinery shaft seal leakage characteristic test. In addition, since the first back pressure valve 7 and the second back pressure valve 8 are independent of each other, the compressor 1 shaft seal leakage and the turbine 3 shaft seal leakage under different back pressure conditions can be measured simultaneously, so as to achieve high efficiency and flexibility of the test.

[0058] (2) The supercritical CO2 rotary machinery shaft seal leakage test system provided by the present invention can, by providing a working fluid recovery unit, reintroduce the working fluid gas leaked through the compressor shaft seal outlet 101 and the turbine shaft seal outlet 301 into the compressor 1 through the working fluid recovery unit and continue to circulate in the system. Compared with the direct discharge solution in the prior art, it can effectively avoid the leakage loss of the circulating system working fluid, maintain the stable operation of the test system, and make the test process efficient and reliable.

[0059] (3) The back pressure control method provided by the present invention obtains the first pressure data and the first flow data of the compressor shaft seal outlet 101, the second pressure data and the second flow data of the turbine shaft seal outlet 301, and determines the shaft seal leakage of the compressor 1 under the set back pressure condition according to the first pressure data and the first flow data, determines the shaft seal leakage of the turbine 3 under the set back pressure condition according to the second pressure data and the second flow data, and finally determines the opening of the first back pressure valve 7 according to the shaft seal leakage of the compressor 1 under the set back pressure condition, and determines the opening of the second back pressure valve 8 based on the shaft seal leakage of the turbine 3 under the set back pressure condition. It is possible to realize adaptive adjustment of the openings of the first back pressure valve 7 and the second back pressure valve 8, and through repeated tests for multiple times, it is possible to obtain the shaft seal leakage test results of the compressor 1 and the turbine 3 under multiple sets of back pressure conditions.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A supercritical CO2 rotary machinery shaft seal leakage test system, characterized in that: include: A compressor, a heat source, a turbine, a cooler, a first back pressure regulating storage tank and a second back pressure regulating storage tank; The outlet end of the compressor is connected to the inlet end of the heat source, the outlet end of the heat source is connected to the inlet end of the turbine, the outlet end of the turbine is connected to the inlet end of the cooler, and the outlet end of the cooler is connected to the inlet end of the compressor; The compressor shaft seal outlet of the compressor is connected to the first back pressure regulating tank, the turbine shaft seal outlet of the turbine is connected to the second back pressure regulating tank, the outlet end of the first back pressure regulating tank is provided with a first back pressure valve, and the outlet end of the second back pressure regulating tank is provided with a second back pressure valve.

2. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 1 is characterized in that: A first pressure sensor and a first flow sensor are provided on a pipeline connecting the compressor shaft seal outlet and the first back pressure regulating tank.

3. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 1 is characterized in that: A second pressure sensor and a second flow sensor are provided on the pipeline connecting the turbine shaft seal outlet and the second back pressure regulating tank.

4. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 1, characterized in that: A first stop valve is provided on the pipeline connecting the compressor shaft seal outlet and the first back pressure regulating tank.

5. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 1, characterized in that: A second stop valve is provided on the pipeline connecting the turbine shaft seal outlet and the second back pressure regulating storage tank.

6. The supercritical CO2 rotating machinery shaft seal leakage test system according to any one of claims 1 to 5, characterized in that: It also includes a working fluid recovery unit, wherein the outlet ends of the first back pressure regulating storage tank and the second back pressure regulating storage tank are both connected to the inlet end of the working fluid recovery unit, and the outlet end of the working fluid recovery unit is connected to the inlet end of the compressor.

7. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 6, characterized in that: The working fluid recovery unit includes a liquefier, a liquid storage tank, a gas storage tank and a heater connected in sequence, the outlet ends of the first back pressure regulating tank and the second back pressure regulating tank are both connected to the inlet end of the liquefier, and the outlet end of the heater is connected to the inlet end of the compressor.

8. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 7, characterized in that: The inlet end of the liquefier is provided with a regulating valve; And / or, a throttle valve is provided on the pipeline connecting the liquid storage tank and the gas storage tank; And / or, a third stop valve is provided on the pipeline connecting the heater and the compressor; And / or, a booster pump is provided at the outlet end of the liquefier.

9. The supercritical CO2 rotating machinery shaft seal leakage test system according to claim 7, characterized in that: A third back pressure valve is provided on the pipeline connecting the gas storage tank and the heater.

10. A back pressure control method based on the supercritical CO2 rotating machinery shaft seal leakage test system according to any one of claims 1 to 9, characterized in that: include: Acquire first pressure data and first flow data of a compressor shaft seal outlet, and acquire second pressure data and second flow data of a turbine shaft seal outlet; determining a shaft seal leakage amount of the compressor under a set back pressure based on the first pressure data and the first flow data, and determining a shaft seal leakage amount of the turbine under a set back pressure based on the second pressure data and the second flow data; The opening of the first back-pressure valve is determined based on the shaft seal leakage of the compressor under the set back pressure, and the opening of the second back-pressure valve is determined based on the shaft seal leakage of the turbine under the set back pressure.

Images