Supercritical CO2 axial flow turbine unit with controllable axial force and axial force measuring and adjusting method thereof

Abstract

The invention discloses a supercritical CO2 axial flow turbine set with controllable axial force and an axial force measuring and adjusting method thereof.The axial flow turbine set comprises an axial flow turbine body which comprises a main shaft, an impeller and an exhaust casing, and the exhaust casing comprises a casing body; the surrounding piece is arranged in the axial cavity, the surrounding piece is a cavity with an opening in one end, the opening end of the cavity abuts against the outlet end of the impeller, the cavity is sealed through the outlet end of the impeller, and a closed pressure adjusting cavity is defined by the impeller and the surrounding piece; the connecting ribs are used for connecting and fixing the surrounding piece to the casing body; a high pressure working medium storage tank and a low pressure working medium storage tank; wherein the pressure regulating cavity is in fluid communication with the high-pressure working medium storage tank and the low-pressure working medium storage tank, the high-pressure working medium storage tank is used for supplying a high-pressure working medium to the pressure regulating cavity, and the low-pressure working medium storage tank is used for receiving a low-pressure working medium from the pressure regulating cavity. The axial force is obtained on the basis that the functions of main components of the turbine unit are not affected, and the axial force can be adjusted within a large range.

Description

Technical Field

[0001] The invention relates to the field of axial force measurement and regulation of a supercritical carbon dioxide axial flow turbine set, and more specifically to a supercritical carbon dioxide axial flow turbine set with controllable axial force and an axial force measurement and regulation method thereof. Background Art

[0002] Supercritical CO2 turbines have the characteristics of high pressure, high speed, and complex operating conditions, which leads to large axial force of the turbine, and the axial force of the turbine changes greatly with the operating conditions. In supercritical CO2 turbines, axial force plays a vital role in the stable operation of the equipment. On the one hand, excessive design of turbine axial force will put higher requirements on the bearing's load-bearing capacity, greatly increasing the difficulty of bearing design; on the other hand, if the axial force of the turbine exceeds the bearing's load-bearing capacity during operation, it will cause bearing failure and damage the moving and static parts inside the turbine unit. Therefore, how to effectively control the axial force over a large range without increasing the axial force design, and how to measure the turbine axial force for precise control, is a key issue in the design of supercritical CO2 turbines.

[0003] In the prior art, due to the limitation of the turbine shaft system size, its axial force is generally difficult to measure, or it can only be directly measured by designing a force sensor inside the bearing, which will affect the design of the bearing and increase the difficulty of shaft system design. In addition, the adjustable range of the traditional adjustment method is small, making it difficult to achieve adjustment within the entire operating range during the actual operation of the turbine.

[0004] Therefore, there is an urgent need in the art for a device that can adapt to various supercritical carbon dioxide turbine operating conditions without increasing the axial force design and affecting the turbine shaft system design, and can control the axial force over a wide range, and preferably can accurately measure and adjust the axial force. Summary of the invention

[0005] The purpose of the present invention is to provide a supercritical carbon dioxide axial flow turbine unit with controllable axial force and a method for measuring and adjusting the axial force thereof, so as to solve the problem of small axial force adjustment range and difficulty in measuring the axial force in the prior art. The present invention can adjust the axial force in a wide range without damaging the main components of the turbine unit, affecting the shaft system design of the turbine unit and the maximum load that can be borne, and can accurately adjust the axial force through axial force measurement and calculation.

[0006] In a first aspect of the present invention, there is provided a supercritical carbon dioxide axial flow turbine unit with controllable axial force, the axial flow turbine unit comprising:

[0007] An axial flow turbine body, the axial flow turbine body comprising a main shaft, an impeller fixed at the end of the main shaft and used to drive the main shaft to rotate, and an exhaust casing for providing peripheral fixed support for the impeller, wherein the exhaust casing comprises:

[0008] A casing body, the casing body is arranged around the outer circumference of the impeller and has an axial cavity for the circulation of supercritical carbon dioxide after work;

[0009] A surrounding member, the surrounding member is arranged in the axial cavity, the surrounding member is a cavity with one end open, the open end of the cavity abuts against the outlet end of the impeller, the cavity is sealed by the outlet end of the impeller, the impeller and the surrounding member form a closed pressure regulating cavity, and the pressure regulating cavity is coaxially arranged with the main shaft; and

[0010] A plurality of connecting ribs, wherein the plurality of connecting ribs are used to connect and fix the enclosure to the casing body;

[0011] A high-pressure working fluid storage tank, the pressure of which is greater than 20 MPa, and

[0012] A low-pressure working fluid storage tank, wherein the pressure of the low-pressure working fluid storage tank is less than 2Mpa;

[0013] The pressure regulating chamber is fluidly connected to the high-pressure working fluid storage tank and the low-pressure working fluid storage tank respectively, the high-pressure working fluid storage tank is used to supply high-pressure working fluid to the pressure regulating chamber, and the low-pressure working fluid storage tank is used to receive low-pressure working fluid from the pressure regulating chamber.

[0014] In another preferred embodiment, the temperature of the supercritical carbon dioxide entering the axial flow turbine body is 400-600° C., and the pressure is 13.5-19.5 MPa.

[0015] In another preferred example, the supercritical carbon dioxide enters the axial flow turbine body through the working fluid air inlet. When passing through the stationary blades installed on the partition, the working fluid (carbon dioxide) further expands and accelerates, and changes the direction of the airflow, so that the airflow impacts the blades on the axial flow impeller at a suitable angle, converting the kinetic energy of the working fluid into mechanical energy. The axial flow impeller rotates and drives the main shaft to rotate to output energy.

[0016] In another preferred example, the axial flow turbine unit achieves bidirectional regulation of the axial force by controlling the pressure in the pressure regulating chamber.

[0017] In another preferred example, the axial force provided by the axial flow turbine unit through controlling the pressure regulating chamber has an adjustment range of -25000N to +25000N.

[0018] In another preferred embodiment, the opening end of the enclosure and the outlet end of the impeller are sealed by a comb seal.

[0019] In another preferred example, one end of the connecting rib is connected and fixed to the closed end of the enclosure, and the other end is connected and fixed to the casing body.

[0020] In another preferred example, the plurality of connecting ribs are arranged evenly spaced apart in the circumferential direction about the axis of the main shaft.

[0021] In another preferred example, the pressure regulating chamber is in fluid communication with the high-pressure working fluid storage tank through a pressure regulating air inlet hole, and is in fluid communication with the low-pressure working fluid storage tank through a pressure regulating air outlet hole.

[0022] In another preferred example, the pressure-regulating air bleed hole and the pressure-regulating air exhaust hole are through holes extending from the pressure-regulating chamber through the surrounding piece, the connecting rib and the casing body to the outside.

[0023] In another preferred example, the number of the pressure-regulating air inlet hole is at least one; the number of the pressure-regulating air outlet hole is at least one.

[0024] In another preferred example, when there are a plurality of the pressure-regulating air inlet holes and the pressure-regulating air outlet holes, the pressure-regulating air inlet holes and the pressure-regulating air outlet holes are evenly spaced apart in the circumferential direction about the axis of the main shaft.

[0025] In another preferred example, a first pressure regulating valve is provided on the pipeline from the pressure regulating chamber to the high-pressure working fluid storage tank, and the first pressure regulating valve is used to control the amount of high-pressure working fluid injected from the high-pressure working fluid storage tank into the pressure regulating chamber, thereby achieving an increase in the pressure in the pressure regulating chamber.

[0026] In another preferred example, a discharge valve is provided on the pipeline from the pressure regulating chamber to the low-pressure working fluid storage tank, and the discharge valve is used to control the amount of working fluid discharged from the pressure regulating chamber to the low-pressure working fluid storage tank, thereby reducing the pressure in the pressure regulating chamber.

[0027] In another preferred embodiment, a sealing chamber is further provided in the axial flow turbine body, and the sealing chamber is surrounded by the main shaft, a partition plate that abuts against the inlet end of the impeller and is sleeved on the main shaft, a cover plate, and a dry gas sealing device sleeved on the main shaft.

[0028] In another preferred example, the sealed cavity is in fluid communication with the high-pressure working fluid storage tank, and the high-pressure working fluid storage tank is used to provide high-pressure working fluid to the sealed cavity.

[0029] In another preferred example, the sealed cavity is in fluid communication with the high-pressure working fluid storage tank via a sealed pressure-inducing hole.

[0030] In another preferred example, the sealing pressure-inducing hole is arranged on the cover plate, and is a through hole extending from the sealing cavity through the cover plate to the outside.

[0031] In another preferred example, a second pressure regulating valve is provided on the pipeline from the high-pressure working fluid storage tank to the pressure regulating chamber, and the second pressure regulating valve is used to control the amount of high-pressure working fluid injected from the high-pressure working fluid storage tank into the sealed chamber, thereby achieving an increase in the pressure in the sealed chamber.

[0032] In another preferred example, the axial flow turbine unit achieves unidirectional regulation of the axial force by controlling the pressure in the sealing chamber.

[0033] In another preferred example, the unidirectional adjustment of the axial force of the axial turbine unit is achieved by controlling the amount of high-pressure working fluid injected from the high-pressure working fluid storage tank into the sealed chamber.

[0034] In another preferred embodiment, the one-way adjustment is performed by applying a force along the main shaft axis from the impeller inlet end to the impeller outlet end for adjustment.

[0035] In another preferred example, the axial force provided by the axial flow turbine unit through controlling the sealing chamber is adjusted in the range of 0 to 3000N.

[0036] In another preferred example, the axial flow turbine unit further includes a measuring module, which includes a plurality of pressure sensors, and measures the pressures of the turbine impeller inlet, outlet, the sealing chamber and the pressure regulating chamber through the plurality of pressure sensors.

[0037] In another preferred embodiment, pressure-inducing holes are designed at the turbine impeller inlet, impeller outlet, sealing chamber and regulating chamber to connect the working fluid at each location to the axial force measurement pressure sensor, which is used to measure the pressure at each location to calculate the turbine axial force.

[0038] In another preferred embodiment, a pressure inlet hole is provided at the inlet of the impeller and the outlet of the impeller, and a pressure sensor is provided at the pressure inlet hole to measure the impeller inlet pressure P in and the impeller outlet pressure P out .

[0039] In another preferred embodiment, pressure inlet holes are provided at the inlet and outlet of the pressure regulating chamber, and pressure sensors are provided at the inlet pressure inlet hole and / or the outlet pressure inlet hole, and the pressure P of the pressure regulating chamber is measured by the pressure sensor. control .

[0040] In another preferred embodiment, a pressure induction hole is provided at the inlet of the sealed cavity, and a pressure sensor is provided at the pressure induction hole, and the pressure P of the sealed cavity is measured by the pressure sensor. seal .

[0041] In another preferred embodiment, the axial flow turbine unit further comprises a controller, which is used to calculate the impeller inlet pressure P based on the pressure data from the pressure sensor (the impeller inlet pressure P in , the impeller outlet pressure P out , the pressure P of the pressure regulating chamber control and the pressure P of the sealed chamber seal ) and the design parameters of the axial flow turbine unit (radius R1 of the main shaft, radial distance R2 from the axis of the main shaft to the outer edge of the inlet side of the impeller, radial distance R3 from the axis of the main shaft to the outer edge of the outlet side of the impeller, radial distance R4 from the axis of the main shaft to the inner edge of the outlet side of the impeller, radial distance R5 from the axis of the main shaft to the outer edge of the outlet side of the impeller, radial distance R6 from the axis of the main shaft to the outer edge of the inlet side of the impeller, radial distance R7 from the axis of the main shaft to the outer edge of the dry gas seal device seal1 and the radial distance R from the axis of the main shaft to the inner edge of the dry gas sealing device seal2 etc.) to calculate the axial force resultant of the axial flow turbine set, and by adjusting the pressure P of the pressure regulating chamber control and the pressure P of the sealed chamber seal To adjust the axial force.

[0042] In another preferred embodiment, a comb seal is designed between the impeller and the turbine exhaust casing to maintain the pressure in the turbine exhaust pressure regulating chamber.

[0043] In another preferred example, the inlet pressure of the supercritical carbon dioxide axial flow turbine body is in the range of 13.5 to 19.5 MPa, and the turbine outlet pressure is in the range of 8 to 9 MPa.

[0044] In another preferred example, the axial flow turbine unit includes a high-speed motor, and the high-speed motor is coaxially connected to the axial flow turbine body.

[0045] In another preferred example, the high-speed motor is an integrated starting motor.

[0046] In another preferred example, in the starting condition, the integrated starting motor drives the turbine to operate, and in the power generation condition, the integrated starting motor converts the shaft power of the turbine into electrical energy.

[0047] In a second aspect of the present invention, a method for measuring and adjusting the axial force of a supercritical carbon dioxide axial flow turbine unit with controllable axial force is provided, the method comprising:

[0048] (1) Providing an axial flow turbine unit according to any one of claims 1 to 8;

[0049] (2) The axial force F of the axial flow turbine set is the axial force F1 on the inlet side of the impeller disk, the axial force F2 on the inlet side of the impeller blade, the axial force F3 on the outlet side of the blade, the axial force F4 on the outlet side of the impeller disk, the axial force F5 of the adjustable cavity on the impeller, and the axial force F5 of the dry gas seal from the sealing cavity. seal sum;

[0050] (3) The axial force F of the axial flow turbine unit is adjusted by adjusting the pressure in the pressure regulating chamber and optionally adjusting the pressure in the sealing chamber.

[0051] In another preferred embodiment, in step (2), the impeller inlet pressure P in , unit: MPa, impeller outlet pressure P out , unit: MPa, pressure regulating chamber pressure P control , unit: MPa to obtain the axial force F1 on the inlet side of the wheel disc, the axial force F2 on the inlet side of the blade, the axial force F3 on the outlet side of the blade, the axial force F4 on the outlet side of the wheel disc, and the axial force F5 of the adjustable cavity on the impeller; and optionally, through the sealing chamber pressure P seal Get the dry gas seal axial force F seal ;

[0052] in,

[0053] Wherein m represents that the force bearing surface of the impeller disk of the impeller is equally divided into m annular regions, and the radial width of each annular region is the same, wherein m is 20-100; f n It represents the axial force on the inlet side of the nth annular area, unit: N;

[0054]

[0055] Among them, P n It represents the inlet side pressure of the nth annular area, unit: MPa; P n-1 Indicates the inlet side pressure of the n-1th annular area, unit: MPa; r n represents the radial distance from the axis center of the main axis to the outer edge of the nth annular region, in m;

[0056]

[0057] Wherein, R1 represents the radius of the main shaft, unit: m; R2 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the wheel disc, unit: m; P0 = P in ;u n represents the tangential velocity of the nth annular area, unit: m / min; un-1 represents the tangential velocity of the n-1th annular area, unit: m / min;

[0058]

[0059] Wherein, N is the rotation speed of the impeller, in r / min;

[0060] The n-1th annular region is adjacent to the nth annular region, and the n-1th annular region is inside the nth annular region (i.e., the n-1th annular region is closer to the center of the impeller than the nth annular region);

[0061]

[0062] Wherein, R6 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the impeller, unit: m;

[0063]

[0064] Wherein, R5 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m; R3 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m;

[0065]

[0066] Wherein, R4 represents the radial distance from the axis of the main shaft to the inner edge of the outlet side of the wheel disc, unit: m;

[0067]

[0068]

[0069] Among them, R seal1 It represents the radial distance from the axis of the main shaft to the outer edge of the dry gas sealing device, unit: m; R seal2 It represents the radial distance from the axis of the main shaft to the inner edge of the dry gas sealing device, unit: m.

[0070] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0072] Figure 1 It is an overall schematic diagram of a supercritical carbon dioxide axial flow turbine unit with controllable axial force in one embodiment of the present invention;

[0073] Figure 2 yes Figure 1 A longitudinal cross-sectional view of a supercritical carbon dioxide axial flow turbine body;

[0074] Figure 3 for Figure 2 Schematic diagram of the axial force composition of the supercritical carbon dioxide axial flow turbine unit.

[0075] In each of the accompanying drawings, the symbols are as follows:

[0076] 1. Starter-generator integrated motor;

[0077] 2. Axial flow turbine body;

[0078] 2.3, Sealed cavity;

[0079] 3. The first pressure regulating valve;

[0080] 4. Discharge valve;

[0081] 5. Low-pressure working fluid storage tank;

[0082] 6. High-pressure working fluid storage tank;

[0083] 7. Second pressure regulating valve;

[0084] 8. Measurement module;

[0085] 2.1. Dry gas seal;

[0086] 2.2, cover plate;

[0087] 2.3, Sealed cavity;

[0088] 2.4. Seal the pressure-inducing hole;

[0089] 2.5, air intake casing;

[0090] 2.6, impeller;

[0091] 2.7, pressure regulating air vent;

[0092] 2.8, Exhaust casing;

[0093] 2.9, pressure regulating exhaust hole;

[0094] 2.10, pressure regulating chamber;

[0095] 2.11, Comb seal;

[0096] 2.12, partition;

[0097] 2.13, Enclosure;

[0098] 2.14, spindle;

[0099] 2.15. Connecting ribs. DETAILED DESCRIPTION

[0100] After extensive and in-depth research and a large number of screenings, the inventor has developed for the first time a supercritical carbon dioxide axial flow turbine unit with controllable axial force and a method for measuring and adjusting the axial force thereof. The present invention can adjust the axial force in a wide range without damaging the main components of the turbine unit, affecting the shaft system design of the turbine unit and the maximum load that can be borne, and can accurately adjust the axial force through axial force measurement and calculation. On this basis, the present invention was completed.

[0101] the term

[0102] As used herein, the term "supercritical carbon dioxide (sCO2)" refers to carbon dioxide that is in a state different from gas and liquid under high pressure and high temperature (exceeding its critical point temperature and pressure: critical point temperature 31.1°C, critical point pressure 7.38MPa), and has the advantages of high density, high thermal conductivity and low viscosity. These characteristics make it an efficient thermal cycle working fluid.

[0103] As used herein, the term "supercritical carbon dioxide axial flow turbine body" is an axial flow turbine device that uses supercritical carbon dioxide (sCO2) as a working medium. The body is the core structure of the turbine, which is mainly used to efficiently convert thermal energy into mechanical energy and has broad application prospects in energy, power generation and industrial power systems.

[0104] As used herein, the term "starter-generator" is an electromechanical device that integrates the starting function and the power generation function in the same device. The starter-generator can be used as a starter to provide the power required when the device is started. For example, in a car engine, the starter-generator can replace the traditional starter to complete the engine starting. When the device is running, the motor can act as a generator to convert mechanical energy into electrical energy for charging the battery or powering the system.

[0105] The main advantages of the present invention include:

[0106] (a) Obtain axial force data without damaging the main components of the turbine set, affecting the design of the turbine set shaft system and the maximum load that it can withstand;

[0107] (b) The axial force can be adjusted within a wide range;

[0108] (c) The axial force data is accurate;

[0109] (d) Rapid adjustment of axial force.

[0110] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, the accompanying drawings are schematic diagrams, so the device and apparatus of the present invention are not limited by the size or ratio of the schematic diagrams.

[0111] It should be noted that in the claims and description of this patent, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0112] Example

[0113] The supercritical carbon dioxide axial flow turbine unit with controllable axial force in this embodiment can adjust the axial force within a wide range without damaging the main components of the turbine unit, affecting the shaft system design of the turbine unit and the maximum force load that can be sustained, and can accurately adjust the axial force through axial force measurement and calculation.

[0114] The axial flow turbine unit of this embodiment includes a supercritical carbon dioxide axial flow turbine body 2, which has the function of converting the thermal energy of the high-temperature and high-pressure working fluid into shaft power. Supercritical carbon dioxide enters the axial flow turbine body 2 through the working fluid air inlet. When passing through the stationary blades installed on the partition 2.12, the working fluid (carbon dioxide) further expands and accelerates, and changes the direction of the airflow, so that the airflow impacts the blades on the axial flow impeller 2.6 at a suitable angle, converting the kinetic energy of the working fluid into mechanical energy. The axial flow impeller 2.6 rotates and drives the main shaft 2.14 to rotate to output energy. The temperature of the supercritical carbon dioxide entering the axial flow turbine body is 400-600°C, and the pressure is 13.5-19.5Mpa. The turbine inlet pressure is in the range of 13.5-19.5Mpa, and the turbine outlet pressure is in the range of 8-9Mpa.

[0115] The axial flow turbine body 2 includes a main shaft 2.14, an impeller 2.6 fixed at the end of the main shaft 2.14 and used to drive the main shaft 2.14 to rotate, and an exhaust casing 2.8 used to provide peripheral fixed support for the impeller 2.6. The exhaust casing 2.8 includes a casing body, a surrounding member 2.13, and a plurality of connecting ribs 2.15. The casing body is arranged around the periphery of the impeller 2.6 and has an axial cavity for the circulation of supercritical carbon dioxide after work; the surrounding member 2.13 is arranged in the axial cavity, and the surrounding member 2.13 is a cavity with one end open, and the open end of the cavity is against the outlet end of the impeller 2.6, and the cavity is sealed by the outlet end of the impeller 2.6. The impeller 2.6 and the surrounding member 2.13 enclose a closed pressure regulating cavity 2.10, and the pressure regulating cavity 2.10 is arranged coaxially with the main shaft 2.14; a plurality of connecting ribs 2.15 connect and fix the surrounding member 2.13 to the casing body. The open end of the enclosure 2.13 and the outlet end of the impeller 2.6 are sealed by a comb seal 2.11, thereby maintaining the pressure in the turbine exhaust pressure regulating chamber 2.10. One end of the connecting rib 2.15 is connected and fixed to the closed end of the enclosure 2.13, and the other end is connected and fixed to the casing body. Multiple connecting ribs 2.15 are arranged evenly spaced apart circumferentially about the axis of the main shaft 2.14. The high-pressure working fluid enters from the air inlet of the intake casing 2.5, and is processed at the impeller 2.6. The processed working fluid is discharged through the axial cavity of the exhaust casing 2.8.

[0116] The axial flow turbine unit of this embodiment also includes a high-pressure working fluid storage tank 6 and a low-pressure working fluid storage tank 5. Among them, the pressure regulating chamber 2.10 is fluidically connected to the high-pressure working fluid storage tank 6 through the pressure regulating air ducting hole 2.7, and is fluidically connected to the low-pressure working fluid storage tank 5 through the pressure regulating exhaust hole 2.9. The high-pressure working fluid storage tank 6 is used to supply high-pressure working fluid (high-pressure carbon dioxide, pressure>20Mpa) to the pressure regulating chamber 2.10, and the low-pressure working fluid storage tank 5 is used to receive low-pressure working fluid (low-pressure carbon dioxide) from the pressure regulating chamber 2.10. The pressure of the high-pressure working fluid storage tank 6 is greater than 20Mpa; the pressure of the low-pressure working fluid storage tank 5 is less than 2Mpa. The pressure regulating air ducting hole 2.7 and the pressure regulating exhaust hole 2.9 are both through holes from the pressure regulating chamber 2.10 through the enclosure 2.13, the connecting rib 2.15 and the casing body to the outside. The number of the pressure regulating air ducting hole 2.7 is at least one; the number of the pressure regulating exhaust hole 2.9 is at least one. When there are a plurality of pressure regulating air inlet holes 2.7 and pressure regulating exhaust holes 2.9, the pressure regulating air inlet holes 2.7 and the pressure regulating exhaust holes 2.9 are arranged evenly spaced apart in the circumferential direction about the axis of the main shaft 2.14.

[0117] A first pressure regulating valve 3 is provided on the pipeline from the pressure regulating chamber 2.10 to the high-pressure working fluid storage tank 6. The first pressure regulating valve 3 is used to control the amount of high-pressure working fluid injected from the high-pressure working fluid storage tank 6 into the pressure regulating chamber 2.10. A discharge valve 4 is provided on the pipeline from the pressure regulating chamber 2.10 to the low-pressure working fluid storage tank 5. The discharge valve 4 is used to control the amount of working fluid discharged from the pressure regulating chamber 2.10 to the low-pressure working fluid storage tank 5. The pressure in the pressure regulating chamber 2.10 is controlled by controlling the first pressure regulating valve 3 and the discharge valve 4.

[0118] The axial flow turbine unit realizes bidirectional adjustment of the axial force by controlling the pressure in the pressure regulating chamber 2.10. The axial flow turbine unit provides an axial force adjustment range of -25000N to +25000N by controlling the pressure regulating chamber 2.10.

[0119] The axial flow turbine body 2 of this embodiment is further provided with a sealed chamber 2.3, which is surrounded by a main shaft 2.14, a partition plate 2.12 that abuts against the inlet end of the impeller 2.6 and is sleeved on the main shaft 2.14, a cover plate, and a dry gas sealing device sleeved on the main shaft 2.14. The sealed chamber 2.3 is a turbine dry gas seal 2.1. The sealed chamber 2.3 is in fluid communication with a high-pressure working fluid storage tank 6, and the high-pressure working fluid storage tank 6 is used to provide high-pressure working fluid to the sealed chamber 2.3. The sealed chamber 2.3 is in fluid communication with the high-pressure working fluid storage tank 6 through a sealed pressure induction hole 2.4. The sealed pressure induction hole 2.4 is provided on the cover plate, and is a through hole from the sealed chamber 2.3 through the cover plate to the outside. A second pressure regulating valve 7 is provided on the pipeline from the high-pressure working fluid storage tank 6 to the sealed chamber 2.3, and the second pressure regulating valve 7 is used to control the amount of high-pressure working fluid injected from the high-pressure working fluid storage tank 6 into the sealed chamber 2.3, thereby achieving an increase in the pressure in the sealed chamber 2.3.

[0120] Dry gas seal 2.1 is a sealing technology mainly used in rotating equipment (such as compressors, pumps, etc.) to form a seal and prevent leakage by using dry gas. Dry gas seal 2.1 uses a pair of relatively rotating sealing rings, one of which is a fixed ring and the other is a rotating ring. The surfaces of the two rings are precisely machined so that a tiny gap (usually only a few microns) is formed during operation. The sealing gas is injected into the gap to produce an air film, which isolates the fluid medium in the sealed space, thereby achieving a sealing effect.

[0121] The axial flow turbine unit achieves unidirectional adjustment of the axial force by controlling the pressure in the sealed chamber 2.3. For example, by controlling the amount of high-pressure working fluid (high-pressure carbon dioxide) injected from the high-pressure working fluid storage tank 6 into the sealed chamber 2.3, the unidirectional adjustment of the axial force of the axial turbine unit is achieved. The axial force adjustment range provided by the axial flow turbine unit by controlling the sealed chamber 2.3 is 0 to 3000N.

[0122] The high-pressure working fluid storage tank 6 in fluid communication with the sealed chamber 2.3 and the high-pressure working fluid storage tank 6 in fluid communication with the pressure regulating chamber 2.10 can be the same high-pressure working fluid storage tank or different high-pressure working fluid storage tanks. Figure 1 The same high-pressure working fluid storage tank 6 is shown in FIG.

[0123] When the axial flow turbine body 2 is working, due to the high pressure of the working fluid inside, both the turbine impeller 2.6 and the turbine dry gas seal 2.1 will generate a large axial force.

[0124] It is not possible to achieve a large adjustment of the axial force only through the sealing chamber 2.3. Firstly, if a large amount of working fluid is filled in, the working fluid will enter the mainstream of the turbine and affect the turbine efficiency. Secondly, due to the limitations of the impeller outlet pressure and the dry gas seal 2.1, the turbine sealing chamber pressure cannot be adjusted significantly.

[0125] The high-pressure working fluid storage tank 6 and the low-pressure working fluid storage tank 5 are respectively connected to the pressure regulating chamber 2.10 through the connecting pipeline, the first pressure regulating valve 3 and the discharge valve 4. By inflating a large amount of air into the pressure regulating chamber 2.10 through the high-pressure working fluid storage tank 6 or by releasing a large amount of air from the pressure regulating chamber 2.10 to the low-pressure working fluid storage tank 5, the pressure in the pressure regulating chamber 2.10 can be greatly adjusted, thereby achieving a large-scale two-way adjustment of the axial force.

[0126] The axial flow turbine unit also includes a measuring module 8. The measuring module 8 is composed of a plurality of pressure sensors, which can measure the pressures at the turbine impeller inlet, outlet, sealing chamber 2.3, and pressure regulating chamber 2.10. Pressure-inducing holes are designed at the turbine impeller inlet, turbine impeller outlet, sealing chamber 2.3, and regulating chamber 2.10 to connect the working fluid at each location to the axial force measurement pressure sensor, which is used to measure the pressure at each location to calculate the turbine axial force.

[0127] Specifically, pressure holes are provided at the inlet and outlet of the impeller, and pressure sensors are provided at the pressure holes to measure the impeller inlet pressure P in and impeller outlet pressure P out The inlet and outlet of the pressure regulating chamber 2.10 are also provided with pressure induction holes, and the inlet and outlet of the pressure regulating chamber are provided with pressure induction holes, and a pressure sensor is provided at the inlet pressure induction hole and / or the outlet pressure induction hole, and the pressure P of the pressure regulating chamber is measured by the pressure sensor control A pressure inlet is provided at the inlet of the sealed cavity, and a pressure sensor is provided at the pressure inlet to measure the pressure P of the sealed cavity. seal .

[0128] The axial flow turbine unit also includes a high-speed motor. The high-speed motor is composed of a rotor, bearings, a stator, and a high-speed motor casing. A turbine is installed at one end of the rotor. The high-speed motor is an integrated starter motor (an integrated starter motor refers to a motor that combines the functions of a starter motor and a generator). In the starting condition, the high-speed motor drives the turbine to operate. In the power generation condition, the high-speed motor converts the shaft power of the turbine into electrical energy.

[0129] like Figure 1 As shown: the supercritical carbon dioxide axial flow turbine unit includes a high-speed motor, a supercritical carbon dioxide axial flow turbine body 2 coaxially arranged with the high-speed motor, a pressure regulating module, and a measuring module 8. The high-pressure working fluid storage tank 6, the low-pressure working fluid storage tank 5, the first pressure regulating valve 3, the second pressure regulating valve 7, the discharge valve 4, and the connecting pipeline connecting them with the pressure regulating chamber 2.10 and the sealing chamber 2.3 are collectively referred to as the pressure regulating module.

[0130] The high-speed motor is an integrated starter motor 1. In the starting condition, the integrated starter motor 1 drives the turbine to operate. In the power generation condition, the integrated starter motor 1 converts the shaft power of the turbine into electrical energy. The high-pressure working fluid storage tank 6 (pressure greater than 20Mpa) is inflated into the sealed chamber 2.3 through the second pressure regulating valve 7, which can achieve a small-scale unidirectional adjustment of the axial force of the turbine unit; the high-pressure working fluid storage tank 6 is inflated into the pressure regulating chamber 2.10 through the first pressure regulating valve 3, which can increase the pressure of the pressure regulating chamber 2.10, and the pressure regulating chamber is exhausted to the low-pressure working fluid storage tank 5 (pressure less than 2Mpa) through the discharge valve 4, so that the pressure of the pressure regulating chamber 2.10 is reduced, thereby achieving a large-scale two-way adjustment of the axial force.

[0131] The parameters measured by the measuring module 8 include: the sealing chamber pressure P seal , Impeller inlet pressure P in , Impeller outlet pressure P out , pressure regulating chamber pressure P control , turbine mass flow rate. Through these parameters, the axial force of the axial flow turbine unit can be calculated.

[0132] like Figure 2 As shown: The working principle of the supercritical carbon dioxide axial flow turbine body is: the supercritical carbon dioxide working medium of high temperature (400-600℃) and high pressure (13.5-19.5Mpa) enters the axial flow turbine body from the working medium air inlet, and then when passing through the stationary blades installed on the partition 2.12, the working medium further expands and accelerates, and changes the direction of the airflow, so that the airflow impacts the blades on the axial flow impeller at a suitable angle, converting the kinetic energy of the working medium into mechanical energy, and the axial flow impeller rotates and outputs energy. In order to achieve the sealing between the rotating parts and the stationary parts, the leaking working medium is introduced into the sealing chamber 2.3, and the sealing of the high-pressure working medium is achieved through the dry gas seal 2.1, and the leakage amount is less than 0.1%.

[0133] When the turbine unit is started, speeded up, or operated under variable load, the turbine axial force will change greatly with the operating conditions, so the axial force needs to be controlled. Figure 1 The high-pressure working fluid storage tank 6 is connected to the sealed chamber 2.3 through the pressure regulating valve 7, and the air is inflated into the chamber through the sealed pressure-introducing hole, so that the axial force of the turbine unit can be adjusted in a small range in one direction. The pressure variation range of the sealed chamber 2.3 is small due to the restrictions of the dry gas seal 2.1 and the impeller, and the axial force adjustment capacity of the sealed chamber is about 3000N.

[0134] The high-pressure working fluid storage tank 6 is connected to the pressure regulating air inlet hole 2.7 through the pressure regulating valve 3, and can inflate the pressure regulating chamber 2.10 to increase the pressure of the pressure regulating chamber. The pressure regulating chamber 2.10 is connected to the pressure regulating exhaust hole 2.9 through the pressure regulating valve 3. Figure 1 The discharge valve 4 in the pressure regulating chamber exhausts air to the low-pressure working fluid storage tank 5 (pressure is less than 2Mpa), thereby reducing the pressure in the pressure regulating chamber. Therefore, the pressure regulating chamber can realize bidirectional adjustment of the axial force, and since the pressure regulating chamber is located in the exhaust section of the axial flow turbine, the performance of the axial flow turbine body will not be affected by filling and deflating the pressure regulating chamber, and the pressure regulating capacity range is large, and the axial force adjustment capacity of the chamber is about ±25000N.

[0135] like Figure 3 Shown is a schematic diagram of the axial force composition of the supercritical carbon dioxide axial flow turbine unit, where the formula for the turbine combined force F is shown in Equation 1.

[0136] F=F t +F seal (1)

[0137] Where F t is the resultant axial force on the impeller, calculated using the formula (2), F seal is the axial force on the dry gas seal 2.1, and is calculated using the formula (3).

[0138] F t = = F1 + F2 + F3 + F4 + F5 (2)

[0139] Among them, F1 is the axial force on the inlet side of the impeller; F2 is the axial force on the inlet side of the blade; F3 is the axial force on the outlet side of the blade; F4 is the axial force on the outlet side of the impeller; F5 is the axial force of the adjustable cavity.

[0140]

[0141] Among them, R seal1 It represents the radial distance from the axis of the main shaft to the outer edge of the dry gas sealing device, unit: m; R seal2 It represents the radial distance from the axis of the main shaft to the inner edge of the dry gas sealing device, unit: m.

[0142] The F1 calculation method is as follows:

[0143] The force-bearing surface F1 is equally divided into 40 annular regions, which are then added up in sequence to obtain F1, wherein the radial width of each annular region is the same.

[0144] The calculation formula of F1 is shown in formula (4).

[0145]

[0146] f n Indicates the inlet side axial force on the nth annular area, unit: N. Partial axial force f n It is equal to the product of pressure and area. The calculation formula is shown in (5), where n ranges from 1 to 40.

[0147]

[0148] Where r0 = R2. n It represents the inlet side pressure of the nth annular area, unit: MPa; P n-1 Indicates the inlet side pressure of the n-1th annular area, unit: MPa; r n It represents the radial distance from the axis center of the main axis to the outer edge of the nth annular area, in meters.

[0149] Radius R n The calculation formula is shown in (6), where n ranges from 1 to 40.

[0150]

[0151] Pressure n The calculation formula is shown in (7). Where n ranges from 1 to 40.

[0152]

[0153] Where P0=Pin R1 represents the radius of the main shaft, unit: m; R2 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the wheel disc, unit: m; P0 = P in ;u n represents the tangential velocity of the nth annular area, unit: m / min; u n-1 It represents the tangential velocity of the n-1th annular area, unit: m / min.

[0154] Tangential speed u n The calculation formula of is shown in formula (8), the unit is m / s. N is the speed, the unit is r / min, and the value range of n is 0-40.

[0155]

[0156] Wherein, N is the rotation speed of the impeller, in r / min.

[0157] The n-1th annular region is adjacent to the nth annular region, and the n-1th annular region is inside the nth annular region.

[0158] The calculation method of F2 is as follows:

[0159]

[0160] Wherein, R6 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the impeller, unit: m.

[0161] The calculation method of F3 is as follows:

[0162]

[0163] Among them, R5 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m; R3 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m.

[0164] The calculation method of F4 is as follows:

[0165]

[0166] Wherein, R4 represents the radial distance from the axis of the main shaft to the inner edge of the outlet side of the wheel disc, unit: m.

[0167] The calculation method of F5 is as follows:

[0168]

[0169] The above formula can be used to obtain the combined force F of the turbine, which can be obtained by adjusting the pressure P in the pressure regulating chamber. control and the seal chamber pressure P seal , to control the turbine combined force F, thereby achieving a wide range of axial force adjustment. The above calculations are performed by a controller (not shown).

[0170] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A supercritical carbon dioxide axial flow turbine unit with controllable axial force, characterized in that: The axial flow turbine unit comprises: An axial flow turbine body, the axial flow turbine body comprising a main shaft, an impeller fixed at the end of the main shaft and used to drive the main shaft to rotate, and an exhaust casing for providing peripheral fixed support for the impeller, wherein the exhaust casing comprises: A casing body, the casing body is arranged around the outer circumference of the impeller and has an axial cavity for the circulation of supercritical carbon dioxide after work; A surrounding member, the surrounding member is arranged in the axial cavity, the surrounding member is a cavity with one end open, the open end of the cavity abuts against the outlet end of the impeller, the cavity is sealed by the outlet end of the impeller, the impeller and the surrounding member form a closed pressure regulating cavity, and the pressure regulating cavity is coaxially arranged with the main shaft; and A plurality of connecting ribs, wherein the plurality of connecting ribs are used to connect and fix the enclosure to the casing body; A high-pressure working fluid storage tank, the pressure of which is greater than 20 MPa, and A low-pressure working fluid storage tank, wherein the pressure of the low-pressure working fluid storage tank is less than 2Mpa; The pressure regulating chamber is fluidly connected to the high-pressure working fluid storage tank and the low-pressure working fluid storage tank respectively, the high-pressure working fluid storage tank is used to supply high-pressure working fluid to the pressure regulating chamber, and the low-pressure working fluid storage tank is used to receive low-pressure working fluid from the pressure regulating chamber.

2. The axial flow turbine unit according to claim 1, characterized in that: The axial flow turbine unit realizes bidirectional regulation of the axial force by controlling the pressure in the pressure regulating chamber.

3. The axial flow turbine unit according to claim 2, characterized in that: The axial force provided by the axial flow turbine unit through controlling the pressure regulating chamber has an adjustment range of -25000N to +25000N.

4. The axial flow turbine unit according to claim 1, characterized in that: One end of the connecting rib is connected and fixed to the closed end of the surrounding piece, and the other end is connected and fixed to the casing body.

5. The axial flow turbine unit according to claim 1, characterized in that: A sealing cavity is also provided in the axial flow turbine body, and the sealing cavity is surrounded by the main shaft, a partition plate which abuts against the inlet end of the impeller and is sleeved on the main shaft, a cover plate, and a dry gas sealing device sleeved on the main shaft.

6. The axial flow turbine unit according to claim 5, characterized in that: The sealed cavity is in fluid communication with the high-pressure working fluid storage tank, and the high-pressure working fluid storage tank is used to provide high-pressure working fluid to the sealed cavity.

7. The axial flow turbine assembly according to claim 1, characterized in that: The axial flow turbine unit realizes unidirectional regulation of the axial force by controlling the pressure in the sealing chamber.

8. The axial flow turbine assembly according to claim 7, characterized in that: The axial force provided by the axial flow turbine unit through controlling the sealing chamber can be adjusted in the range of 0 to 3000N.

9. A method for measuring and adjusting the axial force of a supercritical carbon dioxide axial flow turbine unit with controllable axial force, characterized in that: The method comprises: (1) Providing an axial flow turbine unit according to any one of claims 1 to 8; (2) The axial force F of the axial flow turbine set is the axial force F1 on the inlet side of the impeller disk, the axial force F2 on the inlet side of the impeller blade, the axial force F3 on the outlet side of the blade, the axial force F4 on the outlet side of the impeller disk, the axial force F5 of the adjustable cavity on the impeller, and the axial force F5 of the dry gas seal from the sealing cavity. seal sum; (3) The axial force F of the axial flow turbine unit is adjusted by adjusting the pressure in the pressure regulating chamber and optionally adjusting the pressure in the sealing chamber.

10. The method according to claim 9, characterized in that In step (2), the impeller inlet pressure P in , unit: MPa, impeller outlet pressure P out , unit: MPa, pressure regulating chamber pressure P control , unit: MPa to obtain the axial force F1 on the inlet side of the wheel disc, the axial force F2 on the inlet side of the blade, the axial force F3 on the outlet side of the blade, the axial force F4 on the outlet side of the wheel disc, and the axial force F5 of the adjustable cavity on the impeller; and optionally, through the sealing chamber pressure P seal Get the dry gas seal axial force F seal ; in, Wherein m represents that the force bearing surface of the impeller disk of the impeller is equally divided into m annular regions, and the radial width of each annular region is the same, wherein m is 20-100; f n It represents the axial force on the inlet side of the nth annular area, unit: N; Among them, P n It represents the inlet side pressure of the nth annular area, unit: MPa; P n-1 Indicates the inlet side pressure of the n-1th annular area, unit: MPa; r n represents the radial distance from the axis center of the main axis to the outer edge of the nth annular region, unit: m; Wherein, R1 represents the radius of the main shaft, unit: m; R2 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the wheel disc, unit: m; P0 = P in ;u n Indicates the tangential velocity of the nth annular area, unit: m / min; u n-1 Indicates the tangential velocity of the n-1th annular area, unit: m / min; Wherein, N is the rotation speed of the impeller, in r / min; The n-1th annular region is adjacent to the nth annular region, and the n-1th annular region is inside the nth annular region; Wherein, R6 represents the radial distance from the axis of the main shaft to the outer edge of the inlet side of the impeller, unit: m; Wherein, R5 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m; R3 represents the radial distance from the axis of the main shaft to the outer edge of the outlet side of the impeller, unit: m; Wherein, R4 represents the radial distance from the axis of the main shaft to the inner edge of the outlet side of the wheel disc, unit: m; Among them, R seal1 It represents the radial distance from the axis of the main shaft to the outer edge of the dry gas sealing device, unit: m; R seal2 It represents the radial distance from the axis of the main shaft to the inner edge of the dry gas sealing device, unit: m.

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