Dynamic sealing device and power system

Abstract

The application discloses a dynamic sealing device and a power system. The dynamic sealing device comprises a cavity and a dynamic sealing structure; a first cavity is suitable for surrounding a turbine body and is provided with a first inlet and a first outlet, the first inlet is suitable for being connected with a heater, and the first outlet is suitable for being connected with a regenerator; a second cavity is suitable for surrounding a speed reducer connected with a turbine output shaft, the second cavity is provided with a second outlet, and the second outlet is suitable for being connected with a compressor; a third cavity is suitable for surrounding a generator connected with the speed reducer, the third cavity is provided with a third inlet and a third outlet, the third inlet is suitable for being externally connected with a gas supply device, and the third outlet is used for pressure relief; when the power system is operated, the first cavity, the second cavity and the third cavity form a stepped pressure difference. The application improves the sealing structure of the output shaft end of the power system, converts the high-pressure difference and high-speed sealing problem of the output shaft end into a relatively mature low-pressure difference and low-speed sealing problem, effectively reduces the leakage amount of the working medium, and reduces the use cost of the working medium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of supercritical carbon dioxide closed cycle power system, and particularly relates to a dynamic sealing device and a power system. BACKGROUND

[0002] The supercritical carbon dioxide (sCO2) closed cycle power system is a high-efficiency and energy-saving thermal conversion system. The system uses CO2 as a working medium and performs closed cycle work in the form of a Brayton cycle. The pressure range in the cycle system is generally 7.5 MPa-20 MPa. In the entire cycle, the CO2 is always in a supercritical state (critical point 31℃, 7.35 MPa). With the advantages of high density and low viscosity of the sCO2 working medium, the system can achieve high power density power output.

[0003] In the ideal working state of the supercritical carbon dioxide closed cycle power system, the CO2 working medium does not leak and is always maintained in a supercritical state. However, in the actual working process, due to the high rotational speed of the system rotor and the high system pressure, the dynamic sealing technology at the turbine output shaft end is difficult. Poor sealing effect at this position causes the system to gradually deviate from the design working condition, thereby affecting the stable operation of the system.

[0004] The power system is composed of a compressor, a heat exchanger (including a radiator, a regenerator and a heater), a turbine, a speed reducer and a generator. The turbine inlet temperature is generally 300℃-600℃. The CO2 working medium at the front end of the compressor is in a state near the slightly deviated critical point (such as 35℃ and 8.0 MPa). In this state, the working medium properties change sharply with temperature, and is easy to be compressed, thereby being conducive to reducing the working medium compression power consumption. The working medium enters the compressor and is compressed to obtain high-pressure working medium, and then enters the regenerator to absorb part of the heat, and the working medium temperature rises. The working medium further absorbs heat after entering the heater, and the working medium temperature is further increased to form high-temperature and high-pressure CO2 working medium. The working medium enters the turbine and expands to do work, and the output shaft power. The working medium coming out of the turbine enters the regenerator to transfer part of the heat to the compressed working medium, and then enters the cooler to reduce the temperature and pressure to the compressor inlet state, thereby completing the closed cycle of the working medium.

[0005] In engineering applications, various types of sealing devices are needed to seal, limit or prevent gas leakage. According to whether the sealing surfaces move relative to each other, it is divided into static sealing and dynamic sealing. Dynamic sealing refers to the sealing interface with relative motion and can prevent the leakage caused by the pressure difference or concentration difference of the fluid medium on both sides of the interface to a certain extent. The dynamic sealing position of the supercritical carbon dioxide closed cycle power system output shaft end is the turbine output shaft end. The pressure difference is large, the rotational speed is high, and the dynamic sealing is difficult. The effect of the conventional single sealing method is often poor.

[0006] To solve the working medium leakage problem of the output shaft end of the supercritical carbon dioxide power system, a combination of a labyrinth and working medium supplement injection is usually used. The labyrinth can be arranged on the rotor or the stator, as a non-contact sealing structure, which uses tooth tip throttling and tooth cavity vortex action to increase flow resistance and control flow, for blocking fluid leakage between high and low pressure cavities. The working medium supplement injection refers to supplementing carbon dioxide working medium at the inlet of the compressor to maintain the required amount of working medium for closed cycle operation.

[0007] However, in actual operation, due to the thermal expansion of the turbine rotor and the centrifugal force, the friction during operation can cause the sealing tooth tip or the corresponding stator part coating to wear or permanently deform, thereby causing the sealing form to fail; without a recovery mechanism for the leaked working medium, continuously supplementing the working medium increases the use cost of the system, in addition, in order to make the power system not deviate from the designed working state, the working medium injected at the inlet of the compressor needs to be appropriate, therefore, it is necessary to monitor the working medium leakage amount at the output end, which further increases the design difficulty of the control system. SUMMARY

[0008] The main purpose of the present application is to provide a dynamic sealing device and a power system, which aims to solve the working medium leakage problem of the output shaft end of the supercritical carbon dioxide power system.

[0009] To achieve the above purpose, the present application provides a dynamic sealing device for installation on the output shaft end of a power system, comprising:

[0010] a cavity, at least having a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is suitable for surrounding the turbine body and is provided with a first inlet and a first outlet, the first inlet is suitable for connecting a heater, and the first outlet is suitable for connecting a regenerator; the second chamber is suitable for surrounding a speed reducer connected with the turbine output shaft, and the second chamber is provided with a second outlet, which is suitable for connecting a compressor; the third chamber is suitable for surrounding a generator connected with the speed reducer through a connecting shaft, and the third chamber is provided with a third inlet and a third outlet, the third inlet is suitable for external connection of a gas supply device, and the third outlet is used for pressure relief;

[0011] when the power system is running, the first chamber, the second chamber and the third chamber form a stepped pressure difference; and

[0012] a dynamic sealing structure is arranged at least one of the connection between the first chamber and the second chamber and the turbine output shaft, and the connection between the second chamber and the third chamber and the connecting shaft.

[0013] Optionally, the dynamic sealing structure is a dry gas sealing structure, a graphite sealing structure, a labyrinth sealing structure or a brush sealing structure.

[0014] Optionally, the second chamber comprises two sub-chambers, the first chamber is separated from the second chamber by a first partition, the two sub-chambers are separated by a second partition, the second chamber is separated from the third chamber by a third partition, the first partition, the second partition and the third partition are all provided with the dynamic sealing structure between the first partition and the output shaft of the turbine, between the second partition and the output shaft of the turbine, and between the third partition and the connecting shaft.

[0015] Optionally, the first chamber comprises a plurality of first sub-chambers connected in sequence; and / or

[0016] the second chamber comprises a plurality of second sub-chambers connected in sequence; and / or

[0017] the third chamber comprises a plurality of third sub-chambers connected in sequence.

[0018] Optionally, the second chamber is provided with two accommodation openings, the two accommodation openings are adapted to respectively accommodate an oil supply joint and an oil return joint of the speed reducer.

[0019] Optionally, a one-way valve for controlling the outflow of the working medium in the second chamber is arranged at the second outlet.

[0020] Optionally, the third inlet is adapted to be connected to a filling gas for maintaining the chamber pressure, and a pressure relief control valve is arranged at the third outlet; and / or

[0021] the first inlet is adapted to be connected to carbon dioxide.

[0022] Optionally, the first chamber is surrounded by an outer casing of the turbine, or is surrounded by a plurality of sealing plates.

[0023] Optionally, the third chamber is provided with a socket interface adapted to be electrically connected to the generator, for transmitting power to external power consuming equipment.

[0024] To achieve the above-mentioned purpose, the application further provides a power system comprising the dynamic sealing device as described above, wherein the dynamic sealing device comprises:

[0025] a cavity body comprising a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is adapted to surround a turbine body and is provided with a first inlet and a first outlet, the first inlet is adapted to be connected to a heater, and the first outlet is adapted to be connected to a regenerator; the second chamber is adapted to surround a speed reducer connected to an output shaft of the turbine, the second chamber is provided with a second outlet adapted to be connected to a compressor; the third chamber is adapted to surround a generator connected to the speed reducer through a connecting shaft, the third chamber is provided with a third inlet and a third outlet, the third inlet is adapted to be externally connected to a gas supply device, and the third outlet is used for pressure relief.

[0026] The first chamber, the second chamber and the third chamber form a stepped pressure difference when the power system is running; and

[0027] A dynamic sealing structure is arranged at at least one of the connection between the first chamber and the second chamber and the turbine output shaft, and the connection between the second chamber and the third chamber and the connecting shaft.

[0028] In the technical scheme of the present application, the dynamic sealing device comprises a cavity and a dynamic sealing structure; the cavity is formed with a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is adapted to surround a turbine body and is provided with a first inlet and a first outlet, the first inlet is adapted to be connected to a heater, and the first outlet is adapted to be connected to a regenerator; the second chamber is adapted to surround a speed reducer connected to a turbine output shaft, and the second chamber is provided with a second outlet adapted to be connected to a compressor; the third chamber is adapted to surround a generator connected to the speed reducer through a connecting shaft, and the third chamber is provided with a third inlet adapted to be externally connected to a gas supply device and a third outlet for pressure relief; when the power system is running, the first chamber, the second chamber and the third chamber form a stepped pressure difference; at least one of the connection between the first chamber and the second chamber and the turbine output shaft, and the connection between the second chamber and the third chamber and the connecting shaft is provided with a dynamic sealing structure. It can be understood that, compared with the traditional end sealing structure of the turbine output shaft, the present application transfers the high pressure difference and high speed sealing problem of the turbine output shaft end of the power system to a more mature low pressure difference and low speed sealing problem, effectively reduces the leakage amount of the working medium, and reduces the use cost of the working medium. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0030] Figure 1 The structural schematic diagram of an embodiment of the dynamic sealing device of the present application;

[0031] Figure 2 The structural schematic diagram of an embodiment of the supercritical carbon dioxide closed cycle power system of the present application.

[0032] EXPLANATION OF DRAWINGS:

[0033] 100, turbine body; 101, output shaft; 102, heater; 103, regenerator; 104, speed reducer; 105, compressor; 106, connecting shaft; 107, generator; 108, radiator; 10, cavity; 20, dynamic sealing structure; 11, first chamber; 12, second chamber; 13, third chamber; 121, sub-chamber; 11a, first inlet; 11b, first outlet; 12a, second outlet; 13a, third inlet; 13b, third outlet; 111, first partition plate; 112, second partition plate; 113, third partition plate; 1041, oil supply joint; 1042, oil return joint; 31, one-way valve; 32, pressure relief control valve; 1071, socket interface.

[0034] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0036] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directionality indications also change accordingly.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connection” and “linking” should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, and can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0038] In addition, the description related to "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text is to include three parallel schemes, for example, "A and / or B" includes A scheme, or B scheme, or A and B schemes. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0039] The present application provides a dynamic sealing device, which can be applied to a high-pressure closed circulation system, especially a supercritical carbon dioxide closed circulation power system, which is not limited here.

[0040] Referring to Figure 1 and Figure 2 In an embodiment of the present application, the dynamic sealing device comprises a cavity 10 and a dynamic sealing structure 20; the cavity 10 is formed with at least a first chamber 11, a second chamber 12 and a third chamber 13 connected in sequence; the first chamber 11 is adapted to surround the turbine body 100 and is provided with a first inlet 11a and a first outlet 11b, the first inlet 11a is adapted to be connected to the heater 102 to introduce supercritical carbon dioxide, and the first outlet 11b is adapted to be connected to the regenerator 103; the second chamber 12 is adapted to surround the speed reducer 104 connected to the turbine output shaft 101, and the second chamber 12 is provided with a second outlet 12a, which is adapted to be connected to the compressor 105; the third chamber 13 is adapted to surround the generator 107 connected to the speed reducer 104 through the connecting shaft 106, and the third chamber 13 is provided with a third inlet 13a and a third outlet 13b, the third inlet 13a is adapted to be connected to the gas supply device, and the third outlet 13b is used for pressure relief; when the power system is running, the first chamber 11, the second chamber 12 and the third chamber 13 form a stepped pressure difference; at least one of the connection between the first chamber 11 and the second chamber 12 and the turbine output shaft 101, and the connection between the second chamber 12 and the third chamber 13 and the connecting shaft 106 is provided with the dynamic sealing structure 20.

[0041] It should be noted that, as Figure 2 shown, the power system of the present embodiment is a supercritical carbon dioxide closed circulation power system, which can include a compressor 105, a radiator 108, a regenerator 103, a heater 102, a turbine body 100 and a generator 107, wherein the turbine body 100 is connected to the generator 107 through the speed reducer 104.

[0042] In this embodiment, the cavity 10 can use the protective shell of each device in the power system (for example, the first chamber 11 can be surrounded by the outer casing of the turbine) and the sealing plate to form several chambers; of course, the sealing plate can also be used to surround, and the specific structure, shape and size of the cavity 10 are not limited here.

[0043] The dynamic sealing structure 20 can adopt a dry gas sealing structure, a graphite sealing structure, a labyrinth sealing structure or a brush sealing structure, which is not limited here. In this embodiment, the dynamic sealing structures 20 at different positions can be the same or different, which is not limited here.

[0044] Preferably, flange interfaces can be arranged at the first inlet 11a, the first outlet 11b, the second outlet 12a, the third inlet 13a and the third outlet 13b to facilitate the connection of the gas pipeline. The third inlet 13a is suitable for introducing the filling gas for maintaining the cavity pressure, and the third outlet 13b is provided with a pressure relief control valve 32. The filling gas of the third chamber 13 can be preferably helium; of course, in addition to being filled with helium, other gases with similar viscosity and density to normal temperature and pressure air can also be used.

[0045] It can be understood that, compared with the end sealing structure of the traditional turbine output shaft 101, the present application adopts a multi-chamber to isolate each region to form a stepped pressure difference, which reduces the difficulty of dynamic sealing, and converts the high-pressure difference and high-speed sealing problem of the turbine output shaft 101 end of the power system into a relatively mature low-pressure difference and low-speed sealing problem, effectively reduces the leakage amount of the working medium, and reduces the use cost of the working medium. In addition, in the present application, the low-density gas is injected into the third chamber 13 of the generator 107, which can maintain the cavity pressure without increasing the wind resistance loss of the rotating part caused by the gas.

[0046] According to the provisions of the dynamic leakage amount of the dry gas seal under different diameters and pressures in the existing mechanical industry standard JB / T11289-2012 "Dry gas sealing technical conditions". Assuming that the rotating speed of the power turbine output shaft 101 is 30000r / min~60000r / min, the effective action diameter of the sealing ring is 120mm~160mm, and the sealing gas pressure is 10MPa~15MPa, the allowable leakage amount is <33.5Nm 3 / h.

[0047] According to the calculation, by using the stepped pressure difference dynamic sealing device of the present application, only considering the leakage amount of the generator 107, after the speed reducer 104, the rotating speed of the generator 107 can reach 5000r / min~10000r / min, the effective action diameter is unchanged, and the sealing pressure is 2MPa~5Mpa, at this time the allowable leakage amount is <8.7Nm 3 / h.

[0048] To further reduce the pressure difference between adjacent chambers, to further reduce the difficulty of dynamic sealing, to reduce the leakage of working medium, and to reduce the cost of working medium, with reference to Figure 1 and Figure 2 In an embodiment, the second chamber 12 can include two sub-chambers 121, the first chamber 11 is separated from the second chamber 12 by the first partition 111, the two sub-chambers 121 are separated by the second partition 112, the second chamber 12 is separated from the third chamber 13 by the third partition 113, and the first partition 111, the second partition 112, and the third partition 113 are all provided with dynamic sealing structures 20 between the turbine output shaft 101 and the connecting shaft 106.

[0049] In this embodiment, the second chamber 12 is provided with two accommodation openings, which are suitable for respectively installing the oil supply joint 1041 and the oil return joint 1042 of the speed reducer 104. A one-way valve 31 for controlling the outflow of working medium in the second chamber 12 can be arranged at the second outlet 12a of the left sub-chamber 121 of the second chamber 12, so as to maintain the system pressure and also play a role in working medium recovery.

[0050] Before the supercritical carbon dioxide closed-cycle power system is started, the oil supply and return system of the speed reducer 104 is opened, lubricating oil enters the inside of the speed reducer 104 from the oil supply joint 1041, helium is filled into the third chamber 13 through the third inlet 13a, and the pressure of the third chamber 13 is maintained at about 2 MPa. After the supercritical carbon dioxide closed-cycle power system is started, the working medium pressure at the first inlet 11a can reach 16 MPa. Since the pressure difference between the first chamber 11 and the second chamber 12 is large, CO2 working medium will leak from the first chamber 11 to the second chamber 12 at this time, the flow rate of the supercritical carbon dioxide closed-cycle power system decreases, and the speed decreases. The control system automatically supplements the working medium to the inlet of the compressor 105 to maintain the system speed. When the pressure of the left sub-chamber 121 of the second chamber 12 reaches 8.5 MPa, the one-way valve 31 is opened (the one-way valve 31 can be set to open when the pressure difference between the two sides reaches 0.5 MPa), and part of the CO2 working medium flows back to the inlet of the compressor 105. After a period of time, the pressure of the right sub-chamber 121 of the second chamber 12 will be maintained between the pressures of the left sub-chamber 121 and the third chamber 13. When too much CO2 working medium leaks from the right sub-chamber 121 of the second chamber 12 to the third chamber 13, the pressure of the third chamber 13 will also rise. When the pressure of the third chamber 13 rises to about 3 MPa, the pressure relief control valve 32 is opened to discharge part of the gas, and multiple times of gas discharge can empty the gas in the third chamber 13 and replenish helium to 2 MPa.

[0051] With reference to Figure 1 and Figure 2In an embodiment, the third chamber 13 can further be provided with a socket interface 1071 adapted to be electrically connected with the generator 107, for transmitting electricity to external electrical equipment.

[0052] In some other embodiments, the first chamber 11 can include a plurality of first sub-chambers connected in sequence, the second chamber 12 can include a plurality of second sub-chambers connected in sequence, and the third chamber 13 can include a plurality of third sub-chambers connected in sequence. That is, the number of inner chambers of the cavity 10 can be more than three, and can be set according to specific requirements.

[0053] The present application further provides a power system including the dynamic sealing device, the specific structure of which is referred to the above embodiments. Since the power system includes all the embodiments and all the schemes of the above dynamic sealing device, it has at least the same technical effects as the above dynamic sealing device, which will not be described here.

[0054] Reference Figure 2 In an embodiment of the present application, the power system is a supercritical carbon dioxide closed cycle power system, which can include a compressor 105, a radiator 108, a regenerator 103, a heater 102, a turbine body 100, and a generator 107.

[0055] The above description is only optional embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or any other equivalent transformation within the concept of the present application, and the contents of the present application and the drawings, are included in the patent protection scope of the present application.

Claims

1. A dynamic sealing device for installation on the output shaft end of a power system, characterized in that, The power system comprises: a cavity, which is formed with a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is adapted to surround a turbine body and is provided with a first inlet and a first outlet, the first inlet is adapted to be connected to a heater, and the first outlet is adapted to be connected to a regenerator; the second chamber is adapted to surround a speed reducer connected to a turbine output shaft, and is provided with a second outlet adapted to be connected to a compressor; the third chamber is adapted to surround a generator connected to the speed reducer through a connecting shaft, and is provided with a third inlet and a third outlet, the third inlet is adapted to be externally connected to a gas supply device, and the third outlet is used for pressure relief; when the power system is in operation, the first chamber, the second chamber and the third chamber form a stepped pressure difference; and a dynamic sealing structure, which is arranged at least one of between the first chamber and the second chamber and the turbine output shaft, between the second chamber and the third chamber and the connecting shaft.

2. The dynamic sealing device of claim 1, wherein The dynamic sealing structure is a dry gas sealing structure, a graphite sealing structure, a labyrinth sealing structure or a brush sealing structure.

3. The dynamic sealing device of claim 1, wherein, The second chamber comprises two sub-chambers, the first chamber and the second chamber are separated by a first partition plate, the two sub-chambers are separated by a second partition plate, and the second chamber and the third chamber are separated by a third partition plate, and the dynamic sealing structure is arranged between the first partition plate and the turbine output shaft, between the second partition plate and the turbine output shaft, and between the third partition plate and the connecting shaft.

4. The dynamic sealing device of claim 1, wherein, The first chamber comprises a plurality of first sub-chambers connected in sequence; and / or The second chamber comprises a plurality of second sub-chambers connected in sequence; and / or The third chamber comprises a plurality of third sub-chambers connected in sequence.

5. The dynamic sealing device of claim 1, wherein The second chamber is provided with two accommodation openings, and the two accommodation openings are adapted to respectively accommodate an oil supply connector and an oil return connector of the speed reducer.

6. The dynamic sealing device of claim 1, wherein A one-way valve for controlling the outflow of a working medium in the second chamber is arranged at the second outlet.

7. The dynamic sealing device of claim 1, wherein The third inlet is adapted to be connected to a filling gas for maintaining cavity pressure, and a pressure relief control valve is arranged at the third outlet; and / or The first inlet is adapted to be connected to carbon dioxide.

8. The dynamic sealing device of claim 1, wherein, The first chamber is surrounded by an outer casing of the turbine or a plurality of sealing plates.

9. The dynamic sealing device of claim 1, wherein The third chamber is provided with a socket interface adapted to be electrically connected to the generator, for transmitting power to external power equipment.

10. A power system characterized by, The power system comprises the dynamic sealing device according to any one of claims 1 to 9.

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