Dynamic sealing device and power system

Abstract

The invention discloses a dynamic sealing device and a power system. The dynamic sealing device comprises a cavity and a dynamic sealing structure. The first cavity is suitable for surrounding the 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 heat regenerator; the 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 gas compressor; the 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 an air supply device, and the third outlet is used for pressure relief; when the power system operates, stepped pressure difference is formed by the first cavity, the second cavity and the third cavity. The sealing structure of the output shaft end of the power system is improved, the high-pressure-difference and high-rotating-speed sealing problem of the output shaft end is transferred into the mature low-pressure-difference and low-rotating-speed sealing problem, the working medium leakage amount is effectively reduced, and the working medium use cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of supercritical carbon dioxide closed-cycle power systems, and in particular to a dynamic sealing device and a power system. Background Art

[0002] Supercritical carbon dioxide (sCO 2 ) The closed cycle power system is a highly efficient and energy-saving thermal conversion system that uses CO 2 The working fluid is a closed cycle in the Brayton cycle. The pressure range of the circulation system is generally 7.5MPa to 20MPa. In the whole cycle, CO 2 It is always in a supercritical state (critical point 31°C, 7.35MPa). 2 With the advantages of high density and low viscosity of the working fluid, the system can achieve high power density power output.

[0003] In the ideal working state of the supercritical carbon dioxide closed cycle power system, CO 2 The working fluid does not leak and is always maintained in a supercritical state. However, in the actual working process, due to the high rotor speed and high system pressure of the system, the dynamic sealing technology at the turbine output shaft end is difficult. The poor sealing effect here causes the system to gradually deviate from the design conditions, thereby affecting the stable operation of the system.

[0004] The power system consists of a compressor, a heat exchanger (including a radiator, a regenerator and a heater), a turbine, a reducer and a generator. The turbine inlet temperature is generally between 300°C and 600°C. 2 The working fluid state is near the critical point slightly above (such as 35°C and 8.0MPa). In this state, the working fluid properties change dramatically with temperature and are easily compressed, which is conducive to reducing the power consumption of working fluid compression. The working fluid is compressed after entering the compressor to obtain high-pressure working fluid, and then enters the regenerator to absorb part of the heat, the working fluid temperature rises, and then enters the heater to absorb heat, the working fluid temperature further rises, forming high-temperature and high-pressure CO 2 Working fluid. After entering the turbine, the working fluid expands and performs work, outputting shaft work. The working fluid coming out of the turbine enters the regenerator, transfers part of the heat to the compressed working fluid, and then enters the cooler for cooling. The temperature and pressure are reduced to the compressor inlet state, thus completing the closed cycle of the working fluid.

[0005] In engineering applications, various types of sealing devices are required to seal and limit or prevent gas leakage. According to whether the sealing surfaces move relative to each other, they are divided into static seals and dynamic seals. Dynamic seals refer to relative movement at the sealing interface, and can prevent 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 seal position at the output shaft end of the supercritical carbon dioxide closed cycle power system is the end of the turbine output shaft, where the pressure difference is large and the speed is high, making dynamic sealing difficult. Conventional single sealing methods often have poor effects.

[0006] In order to solve the problem of fluid leakage at the output shaft end of the supercritical carbon dioxide power system, a combination of grate teeth and fluid supplementary injection is often used. The grate teeth can be arranged on the rotor or the stator. As a non-contact sealing structure, it uses the throttling effect of the tooth tip and the vortex effect of the tooth cavity to increase the flow resistance to control the flow rate, and is used to block the fluid leakage between the high and low pressure chambers. Fluid supplementary injection refers to the addition of carbon dioxide working fluid at the compressor inlet to maintain the working mass required 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 will cause the sealing tooth tip or the corresponding stator component coating to wear or permanently deform, thereby causing the sealing form to fail; in the absence of a recovery mechanism for the leaked working fluid, continuous replenishment of the working fluid increases the system's operating cost. In addition, in order to prevent the power system from deviating from the designed working state, the working fluid injected at the compressor inlet must be appropriate, so it is necessary to monitor the leakage of the working fluid at the output end, which increases the difficulty of designing the control system. Summary of the invention

[0008] The main purpose of the present invention is to provide a dynamic sealing device and a power system, aiming to solve the problem of working fluid leakage at the output shaft end of a supercritical carbon dioxide power system.

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

[0010] The cavity is formed with at least a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is suitable for enclosing a 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 enclosing a reducer connected to the turbine output shaft, the second chamber is provided with a second outlet, and the second outlet is suitable for connecting a compressor; the third chamber is suitable for enclosing a generator connected to the reducer via a connecting shaft, the third chamber is provided with a third inlet and a third outlet, the third inlet is suitable for connecting an external air supply device, and the third outlet is used for pressure relief;

[0011] When the power system is running, a stepped pressure difference is formed between the first chamber, the second chamber and the third chamber; and

[0012] A dynamic sealing structure is provided at least at one of a connection between the first chamber and the second chamber and the turbine output shaft and a 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 comb teeth sealing structure or a brush sealing structure.

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

[0015] Optionally, the first chamber includes 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 includes a plurality of third sub-chambers connected in sequence.

[0018] Optionally, the second chamber is provided with two accommodating ports, and the two accommodating ports are suitable for installing the oil supply joint and the oil return joint of the reducer respectively.

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

[0020] Optionally, the third inlet is suitable for introducing a filling gas for maintaining the chamber pressure, and a pressure relief control valve is provided at the third outlet; and / or

[0021] The first inlet is suitable for introducing 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 suitable for being electrically connected to the generator for transmitting electricity to external electrical equipment.

[0024] To achieve the above object, the present invention further proposes a power system, comprising the dynamic sealing device as described above, wherein the dynamic sealing device comprises:

[0025] The cavity is formed with at least a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is suitable for enclosing a 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 enclosing a reducer connected to the turbine output shaft, the second chamber is provided with a second outlet, and the second outlet is suitable for connecting a compressor; the third chamber is suitable for enclosing a generator connected to the reducer via a connecting shaft, the third chamber is provided with a third inlet and a third outlet, the third inlet is suitable for connecting an external air supply device, and the third outlet is used for pressure relief;

[0026] When the power system is running, a stepped pressure difference is formed between the first chamber, the second chamber and the third chamber; and

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

[0028] In the technical solution of the present invention, the dynamic sealing device includes a cavity and a dynamic sealing structure; the cavity is at least formed with a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is suitable for enclosing a 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 heat regenerator; the second chamber is suitable for enclosing a reducer connected to the turbine output shaft, the second chamber is provided with a second outlet, and the second outlet is suitable for connecting a compressor; the third chamber is suitable for enclosing a generator connected to the reducer through a connecting shaft, the third chamber is provided with a third inlet and a third outlet, the third inlet is suitable for an external air supply device, and the third outlet is used for pressure relief; when the power system is running, the first chamber, the second chamber and the third chamber form a stepped pressure difference; a dynamic sealing structure is provided 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. It can be understood that compared with the traditional end sealing structure of the turbine output shaft, the present invention transfers the high pressure difference and high speed sealing problem of the turbine output shaft end of the power system to the more mature low pressure difference and low speed sealing problem, which effectively reduces the leakage of the working fluid and reduces the cost of using the working fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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 the structures shown in these drawings without paying creative work.

[0030] Figure 1 It is a structural schematic diagram of an embodiment of a dynamic sealing device of the present invention;

[0031] Figure 2 It is a structural schematic diagram of an embodiment of a supercritical carbon dioxide closed cycle power system of the present invention.

[0032] Description of Figure Numbers:

[0033] 100. Turbine body; 101. Output shaft; 102. Heater; 103. Regenerator; 104. 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; 112. Second partition; 113. Third partition; 1041. Oil supply connector; 1042. Oil return connector; 31. One-way valve; 32. Pressure relief control valve; 1071. Socket interface.

[0034] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0036] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

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

[0040] Reference Figure 1 and Figure 2 In one embodiment of the present invention, the dynamic sealing device includes a cavity 10 and a dynamic sealing structure 20; the cavity 10 is at least formed with a first chamber 11, a second chamber 12 and a third chamber 13 connected in sequence; the first chamber 11 is suitable for surrounding a turbine body 100 and is provided with a first inlet 11a and a first outlet 11b, the first inlet 11a is suitable for connecting to a heater 102 to introduce supercritical carbon dioxide, and the first outlet 11b is suitable for connecting to a regenerator 103; the second chamber 12 is suitable for surrounding a reducer 104 connected to a turbine output shaft 101, and the second chamber 12 is provided with a second outlet 12a, and the second outlet 12a is suitable for connecting to The third chamber 13 is suitable for enclosing a generator 107 connected to the reducer 104 via a 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 suitable for an external air supply device, and the third outlet 13b is used for pressure relief; when the power system is running, a stepped pressure difference is formed among the first chamber 11, the second chamber 12 and the third chamber 13; a dynamic sealing structure 20 is provided at least at 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.

[0041] Need to explain, such as Figure 2 As shown, the power system of this embodiment is a supercritical carbon dioxide closed cycle power system, which may 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 and the generator 107 are connected via a reducer 104.

[0042] In this embodiment, the cavity 10 can utilize the protective shells of the devices in the power system themselves (for example, the first chamber 11 can be surrounded by the outer casing of the turbine), and then a sealing plate is set to form a plurality of chambers; of course, all of them can also be surrounded by sealing plates, and the specific structure, shape and size of the cavity 10 are not limited here.

[0043] The dynamic sealing structure 20 may be a dry gas sealing structure, a graphite sealing structure, a comb teeth sealing structure or a brush sealing structure, which is not limited here. In this embodiment, the dynamic sealing structures 20 at various locations may be the same or different, which is not limited here.

[0044] Preferably, flange interfaces can be provided 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 a filling gas for maintaining the cavity pressure, and a pressure relief control valve 32 is provided at the third outlet 13b. The filling gas of the third chamber 13 can preferably be helium; of course, in addition to helium, other gases with a viscosity and density similar to that of air at normal temperature and pressure can also be used.

[0045] It can be understood that compared with the traditional end sealing structure of the turbine output shaft 101, the present invention uses multiple chambers to isolate each area to form a stepped pressure difference, which reduces the difficulty of dynamic sealing and transfers the high pressure difference and high speed sealing problem at the end of the turbine output shaft 101 of the power system to a more mature low pressure difference and low speed sealing problem, effectively reducing the leakage of the working fluid and reducing the cost of working fluid use. In addition, in the present invention, low-density gas is injected into the third chamber 13 of the generator 107, which can maintain the chamber pressure without increasing the windage loss caused by the gas to the rotating parts.

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

[0047] After calculation, the step-type differential pressure dynamic seal device of the present invention is used, and only the leakage at the generator 107 is considered. After the reducer 104, the speed of the generator 107 can reach 5000r / min~10000r / min, the effective action diameter remains unchanged, and the sealing pressure is 2MPa~5Mpa. At this time, the allowable leakage is <8.7Nm 3 / h.

[0048] In order to further reduce the pressure difference between adjacent chambers, further reduce the difficulty of dynamic sealing, reduce the leakage of working fluid, and reduce the cost of working fluid use, refer to Figure 1 and Figure 2 In one embodiment, the second chamber 12 may include two sub-chambers 121, the first chamber 11 and the second chamber 12 are separated by a first partition 111, the two sub-chambers 121 are separated by a second partition 112, the second chamber 12 and the third chamber 13 are separated by a third partition 113, and dynamic sealing structures 20 are provided between the first partition 111 and the turbine output shaft 101, between the second partition 112 and the turbine output shaft 101, and between the third partition 113 and the connecting shaft 106.

[0049] In this embodiment, the second chamber 12 is provided with two receiving ports, which are suitable for installing the oil supply connector 1041 and the oil return connector 1042 of the reducer 104. A one-way valve 31 for controlling the outflow of the working fluid in the second chamber 12 can be provided at the second outlet 12a of the left sub-chamber 121 of the second chamber 12, so as to maintain the system pressure and recover the working fluid.

[0050] Before the supercritical carbon dioxide closed cycle power system is started, the oil supply and return system of the reducer 104 is opened, and the lubricating oil enters the reducer 104 from the oil supply joint 1041. At the same time, 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 2MPa. When the supercritical carbon dioxide closed cycle power system is started, the working fluid pressure at the first inlet 11a can reach 16MPa. Due to the large pressure difference between the first chamber 11 and the second chamber 12, the CO 2 The working fluid will leak from the first chamber 11 to the second chamber 12, the flow rate of the supercritical carbon dioxide closed cycle power system will decrease, the speed will drop, and the control system will automatically replenish the working fluid to the compressor 105 inlet to maintain the system speed. When the pressure of the left sub-chamber 121 of the second chamber 12 reaches 8.5MPa, the one-way valve 31 opens (the one-way valve 31 can be set to open when the pressure difference between the two sides reaches 0.5MPa), and part of the CO 2 The working fluid 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 chamber pressures of the left sub-chamber 121 and the third chamber 13. 2 When the working medium is used, the pressure of the third chamber 13 will also rise. When the pressure of the third chamber 13 rises to about 3MPa, the pressure relief control valve 32 is opened to discharge part of the gas. Multiple exhausts can evacuate the gas in the third chamber 13 and refill helium to 2MPa.

[0051] Reference Figure 1 and Figure 2In one embodiment, the third chamber 13 may also be provided with a socket interface 1071 suitable for being electrically connected to the generator 107 for transmitting electricity to external electrical equipment.

[0052] In addition, in some other embodiments, the first chamber 11 may include a plurality of first sub-chambers connected in sequence, the second chamber 12 may also include a plurality of second sub-chambers connected in sequence, and the third chamber 13 may also include a plurality of third sub-chambers connected in sequence. That is, in the present invention, the number of inner chambers of the chamber body 10 may be more than three, which may be set according to specific needs.

[0053] The present invention also proposes a power system, which includes a dynamic sealing device. The specific structure of the dynamic sealing device refers to the above-mentioned embodiment. Since the power system proposed by the present invention includes all schemes of all embodiments of the above-mentioned dynamic sealing device, it has at least the same technical effect as the above-mentioned dynamic sealing device, which will not be elaborated one by one here.

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

[0055] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A dynamic sealing device, used for installation on the output shaft end of a power system, characterized in that: include: The cavity is formed with at least a first chamber, a second chamber and a third chamber connected in sequence; the first chamber is suitable for enclosing a 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 enclosing a reducer connected to the turbine output shaft, the second chamber is provided with a second outlet, and the second outlet is suitable for connecting a compressor; the third chamber is suitable for enclosing a generator connected to the reducer via a connecting shaft, the third chamber is provided with a third inlet and a third outlet, the third inlet is suitable for connecting an external air supply device, and the third outlet is used for pressure relief; When the power system is running, a stepped pressure difference is formed between the first chamber, the second chamber and the third chamber; as well as A dynamic sealing structure is provided at least at one of a connection between the first chamber and the second chamber and the turbine output shaft and a connection between the second chamber and the third chamber and the connecting shaft.

2. The dynamic sealing device according to claim 1, characterized in that: The dynamic sealing structure is a dry gas sealing structure, a graphite sealing structure, a comb teeth sealing structure or a brush sealing structure.

3. The dynamic sealing device according to claim 1, characterized in that: The second chamber includes two sub-chambers, the first chamber and the second chamber are separated by a first partition, the two sub-chambers are separated by a second partition, the second chamber and the third chamber are separated by a third partition, and the dynamic sealing structure is provided between the first partition and the turbine output shaft, between the second partition and the turbine output shaft, and between the third partition and the connecting shaft.

4. The dynamic sealing device according to claim 1, characterized in that: 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 includes a plurality of third sub-chambers connected in sequence.

5. The dynamic sealing device according to claim 1, characterized in that: The second chamber is provided with two accommodating openings, and the two accommodating openings are suitable for installing the oil supply joint and the oil return joint of the reducer respectively.

6. The dynamic sealing device according to claim 1, characterized in that: A one-way valve for controlling the working medium in the second chamber to flow outward is provided at the second outlet.

7. The dynamic sealing device according to claim 1, characterized in that: The third inlet is suitable for introducing a filling gas for maintaining the chamber pressure, and a pressure relief control valve is provided at the third outlet; and / or The first inlet is suitable for introducing carbon dioxide.

8. The dynamic sealing device according to claim 1, characterized in that: The first chamber is surrounded by the outer casing of the turbine, or is surrounded by a plurality of sealing plates.

9. The dynamic sealing device according to claim 1, characterized in that: The third chamber is provided with a socket interface suitable for being electrically connected to the generator and used for transmitting electricity to external electrical equipment.

10. A power system, characterized in that: It comprises a dynamic sealing device as described in any one of claims 1 to 9.

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