A turbine expander self-circulating dry gas seal device

Abstract

The application discloses a kind of turbine expander self-circulation dry gas seal device, including labyrinth seal ring, sealing cavity, front exhaust port, front carbon float ring and dry gas seal body, for the dynamic seal of high-speed small power grade radial flow turbine expander and other fluid machinery.The position of each component is in turn from high-pressure side to low-pressure side, namely labyrinth seal, sealing cavity, front exhaust port, front carbon float ring and dry gas seal body;Among them, labyrinth seal is used as the first sealing structure, which can significantly reduce the process gas pressure discharged into the sealing cavity;Front exhaust port is connected with the low-pressure node of turbine expander inlet and outlet and forms a loop, not only recycles the high-pressure process gas in the sealing cavity to the circulating system, but also significantly reduces the temperature and pressure inside the sealing cavity by the negative feedback effect of the loop;Front carbon float ring and dry gas seal body are used to suppress the leakage of process gas in the sealing cavity to the atmosphere side, improve the working environment of turbine expander dry gas seal device, significantly reduce the technical requirements and construction cost of sealing system, and improve the efficiency-cost ratio of dry gas seal technology in small-scale application scenarios.

Description

Technical Field

[0001] This invention relates to the field of dynamic sealing technology, specifically to a self-circulating dry gas sealing device for a turbine expander. It is mainly applicable to the rotary dynamic sealing system of high-load turbine expanders, radial compressors, and radial turbines, and is particularly suitable for high-temperature, high-pressure, high-load compact closed-loop power cycles. Background Technology

[0002] Dry gas seals are a new type of non-contact seal developed from gas dynamic pressure bearings. Utilizing the hydrodynamic effect of fluids, dry gas seals prevent contact between the two rotating sealing end faces, thus achieving both gas sealing and dry operation. From a manufacturing perspective, dry gas seal devices achieve non-contact operation of the sealing end faces by setting dynamic pressure grooves on the rotating ring of the mechanical seal and corresponding auxiliary systems. In the late 1970s, John Crane Company in the UK pioneered the application of dry gas seals to gas conveying equipment on offshore platforms, achieving great success. According to a 2010 evaluation report released by Sandia National Laboratories (SNL) in the United States, dry gas seals can control the mass flow rate of the leaking working fluid to about 1 / 10 of that of labyrinth seals, making them a highly ideal sealing method. Today, dry gas seals have become the most commonly used dynamic sealing technology in large fluid machinery, large process equipment, and high-power steam / gas turbines.

[0003] While dry gas seals offer significant advantages over traditional sealing technologies such as mechanical seals and toothed seals, achieving better sealing performance, longer service life, and lower vibration disturbance, the technical requirements and manufacturing costs of seals increase rapidly under harsh operating conditions such as high pressure differentials, high temperatures, and high speeds. This is due to the significantly increased technical requirements for component strength (pressure resistance >15MPa), machining precision, and heat resistance (>350℃). For small- to medium-scale applications such as low-power supercritical fluid power cycles, high-load compact turbine expanders, intermittent waste heat recovery systems, and weapon power platforms, the cost-effectiveness of traditional dry gas seals is relatively low. To promote the wider application of dry gas sealing technology, it is necessary not only to impose higher requirements on the sealing performance of sealing devices but also to control the overall cost of sealing devices / systems at a reasonable level. Summary of the Invention

[0004] The purpose of this invention is to provide a self-circulating dry gas sealing device for turbine expanders and other fluid machinery of small and medium power levels, such as low-power supercritical fluid dynamic cycles and high-load compact turbine expander weapon power platforms, thereby improving the cost-effectiveness of dry gas sealing technology in small and medium-scale application scenarios.

[0005] This invention is achieved through the following technical solution:

[0006] A self-circulating dry gas sealing device for a turbine expander includes a volute, an impeller assembly, a labyrinth seal ring, a sealing cavity, a front carbon floating ring, and a dry gas sealing body.

[0007] The impeller assembly is housed within the volute of the mother machine. The labyrinth seal, the pre-mounted carbon float ring, and the dry gas seal body are coaxially mounted on the impeller assembly and arranged sequentially from the working fluid side to the atmospheric side. A sealing cavity is provided between the labyrinth seal ring and the pre-mounted carbon float ring. The gap between the impeller assembly and the volute is connected to the inlet of the labyrinth seal ring, and the labyrinth outlet of the labyrinth seal ring is connected to the sealing cavity. A sealing gas pump port is provided on the volute, through which sealing gas is pressurized and injected into the outer ring surface of the dry gas seal body. The inner ring surface of the dry gas seal body is connected to the sealing cavity through the pre-mounted carbon float ring, and the sealing cavity is connected to the low-pressure node of the mother machine through a self-circulating loop.

[0008] Preferably, the impeller assembly includes an impeller nose cone, a turbine expander main shaft, and a radial impeller;

[0009] The impeller assembly includes an impeller nose cone, a turbine expander main shaft, and a radial impeller. The impeller nose cone is located at the end of the radial impeller and is close to the air inlet of the mother machine. The impeller nose cone and the radial impeller are coaxially connected through the turbine expander main shaft. The end of the turbine expander main shaft extending out of the radial impeller is connected to the main shaft of the motor through a drive shaft.

[0010] Preferably, the end of the turbine expander main shaft is connected to the generator main shaft via a drive shaft, the drive shaft is housed in the volute, and the end of the drive shaft near the atmosphere is provided with an atmospheric side brush seal.

[0011] Preferably, the radial impeller includes an impeller body and a positioning post. One end of the impeller body is connected to a nose cone, and the positioning post is located at the other end of the impeller body. A sealing groove is provided on the volute, and a labyrinth sealing ring is fitted onto the positioning post and located in the sealing groove. Preferably, a sealing cavity is provided between the cold end faces of the impeller body, the volute, and the labyrinth sealing ring. The sealing cavity is an annular cavity, located outside the front carbon floating ring, and the front carbon floating ring communicates with the sealing cavity.

[0012] Preferably, the volute is provided with a front exhaust port, one end of which is connected to the sealing cavity, and the other end of which is connected to the low-pressure node of the mother machine through a self-circulating loop.

[0013] Preferably, when the mother machine is a radial flow compressor, the front exhaust port is connected to the compressor inlet, and the compressor inlet serves as the low-pressure node of the self-circulating loop.

[0014] When the mother machine is a radial flow turbine, the front exhaust port is connected to the outlet of the radial flow turbine, and the outlet of the radial flow turbine serves as the low-pressure node of the self-circulating loop.

[0015] Preferably, the self-circulating loop is equipped with a flow controller to control the return flow of the working fluid and adjust the pressure of the sealing cavity.

[0016] Preferably, the air pump's air port is connected to an air source, and the temperature of the sealing gas generated by the air source is lower than the working fluid temperature at the air inlet.

[0017] Preferably, the pressure of the sealing gas is greater than the pressure of the sealing cavity.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] This invention provides a self-circulating dry gas sealing device for a turbine expander, comprising a labyrinth seal ring, a sealing cavity, a pre-exhaust port, a pre-carbon floating ring, and a dry gas sealing body. It is used for dynamic sealing of fluid machinery such as high-speed, small-to-medium power radial-flow turbine expanders. The components, from the high-pressure side (process gas) to the low-pressure side (atmosphere), are, in sequence: labyrinth seal, sealing cavity, pre-exhaust port, pre-carbon floating ring, and dry gas sealing body. The labyrinth seal, as the primary sealing structure, significantly reduces the pressure of the process gas discharged into the sealing cavity. The pre-exhaust port connects to the low-pressure nodes at the turbine expander's inlet and outlet, forming a loop. This not only recovers the high-pressure process gas from the sealing cavity to the circulation system but also significantly reduces the temperature and pressure inside the sealing cavity through the negative feedback of the loop. The pre-carbon floating ring and dry gas sealing body suppress leakage of process gas from the sealing cavity to the atmosphere, improving the working environment of the turbine expander dry gas sealing device, significantly reducing the technical requirements and construction costs of the sealing system, and improving the cost-effectiveness of dry gas sealing technology in small-to-medium scale applications. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the internal structure of a self-circulating dry gas sealing device for a turbine expander according to the present invention.

[0022] In the diagram: 1. Labyrinth seal ring, 2. Sealing cavity, 3. Front exhaust port, 4. Front carbon float ring, 5. Dry gas seal body, 6. Sealing air pump vent, 7. Atmospheric side brush seal, 8. Impeller nose cone, 9. Turbine expander main shaft, 10. Radial impeller. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0024] See Figure 1 A self-circulating dry gas sealing device for a turbine expander includes a volute, an impeller assembly, a labyrinth seal ring 1, a sealing cavity 2, a front exhaust port 3, a front carbon floating ring 4, and a dry gas sealing body 5.

[0025] The impeller assembly is housed in the volute of the mother machine. The labyrinth seal 1, the pre-mounted carbon float ring 4, and the dry gas sealing body 5 are coaxially mounted on the impeller assembly and arranged sequentially from the working fluid side to the atmospheric side. A sealing cavity 2 is provided between the labyrinth seal ring 1 and the pre-mounted carbon float ring 4. The rotational clearance between the impeller assembly and the volute is connected to the labyrinth inlet of the labyrinth seal ring 1. The outlet of the labyrinth seal ring 1 is connected to the sealing cavity 2. A sealing gas pump port 6 is provided on the volute. The sealing gas is pressurized and injected into the outer ring surface of the dry gas sealing body 5 through the sealing gas pump port 6. The inner ring surface of the dry gas sealing body 5 is connected to the sealing cavity 2 through the pre-mounted carbon float ring 4. The sealing cavity 2 is connected to the vent of the low-pressure node of the mother machine through a self-circulation loop, forming a self-circulation loop for the working fluid (process gas).

[0026] The impeller assembly includes an impeller nose cone 8, a turbine expander main shaft 9, and a radial impeller 10. The impeller nose cone 8 is located at the end of the radial impeller 10 and is close to the air inlet of the mother machine. The impeller nose cone 8 and the radial impeller 10 are coaxially connected by the turbine expander main shaft 9. The end of the turbine expander main shaft 9 that extends out of the radial impeller 10 is connected to the main shaft of the motor through a drive shaft. An atmospheric side brush seal 7 is provided on the drive shaft.

[0027] The radial impeller 10 includes an impeller body and a positioning post. One end of the impeller body is connected to the nose cone 8, and the positioning post is located at the other end of the impeller body. Blades are provided on the side wall of the impeller body, and a sealing groove is provided on the volute. A labyrinth sealing ring 1 is fitted on the positioning post and located in the sealing groove. A rotation gap is provided between the end faces of the impeller body, the volute, and the labyrinth sealing ring 1. The rotation gap forms an airflow channel that connects to the labyrinth inlet of the labyrinth sealing ring 1, and the labyrinth outlet of the labyrinth sealing ring 1 communicates with the sealing cavity 2.

[0028] The sealing cavity 2 is an annular cavity, located outside the front carbon floating ring 4. A gap is provided between the labyrinth sealing ring 1 and the front carbon floating ring 4. The labyrinth outlet of the labyrinth sealing ring 1 is connected to the sealing cavity 2 through the gap. A front exhaust port 3 is provided on the volute. One end of the front exhaust port 3 is connected to the sealing cavity 2, and the other end of the front exhaust port 3 is connected to the low-pressure node of the turbine compressor through a self-circulation loop. The low-pressure node is the vent hole on the low-pressure side.

[0029] The front exhaust port 3 is connected to the low-pressure node of the mother machine to form a self-circulating loop. Through the self-circulating loop, the high-pressure process gas retained in the sealing cavity 2 is not only recovered to the circulation system, but also the temperature and pressure of the process gas in the sealing cavity are significantly reduced by its negative feedback effect. This improves the damage to the mechanical structure and material strength of the dry gas seal body caused by the high temperature and high pressure environment, and achieves the goal of reducing the technical requirements and construction cost of the turbine expander dry gas seal system.

[0030] The self-circulating loop is equipped with a flow controller, which controls the pressure inside the sealed cavity by controlling the return flow of the working fluid, so as to maintain the pressure of the moving parts at a reasonable level.

[0031] The pre-exhaust port is arranged differently depending on the type of the main unit: when the main unit is a radial compressor, the pre-exhaust port is connected to the compressor inlet, and the compressor inlet serves as the low-pressure node of the self-circulation loop. When the main unit is a radial turbine, the pre-exhaust port is connected to the radial turbine outlet, and the turbine outlet serves as the low-pressure node of the self-circulation loop.

[0032] The dry gas sealing body 5 requires external sealing gas assistance during normal operation. The sealing gas pump port 6 is connected to the gas source. The sealing gas generated by the gas source flows into the sealing cavity through the pre-mounted carbon floating ring and mixes with the high-temperature and high-pressure process gas leaking into the sealing cavity from the turbine expander. Under the action of pressure difference, it automatically flows back to the low-pressure nodes of the turbine expander inlet and outlet pipelines through the pre-mounted exhaust port and the self-circulation loop. The return process does not require external pump assistance. In addition, a small portion of the sealing gas is discharged into the atmosphere through the high-point venting device under the guidance of the isolation gas.

[0033] Because the sealing gas has a low temperature, when the sealing gas mixes with the high-temperature process gas leaking from the turbine expander, it can significantly reduce the temperature of the sealing cavity and the hot end face of the labyrinth seal. This reduces the effects of thermal stress and alternating thermal loads on the dry gas seal body 5 and the carbon floating ring under high-temperature conditions, thus playing an important role in cooling and protecting the high-temperature components of the turbine expander's self-circulating dry gas sealing device.

[0034] The sealing gas is sourced from the outlet bleed gas of a centrifugal compressor. After filtration and pressure reduction, it is used as the sealing gas for the dry gas sealing device, and the pressure of the sealing gas is always about 0.5 MPa higher than the pressure of the sealing chamber (process gas).

[0035] This invention provides a self-circulating dry gas sealing device for a turbine expander, comprising a labyrinth seal ring, a sealing cavity, a pre-exhaust port, a pre-carbon floating ring, and a dry gas sealing body. It is used for dynamic sealing of fluid machinery such as high-speed, small-to-medium power radial-flow turbine expanders. The components, from the high-pressure side (process gas) to the low-pressure side (atmosphere), are, in sequence: labyrinth seal, sealing cavity, pre-exhaust port, pre-carbon floating ring, and dry gas sealing body. The labyrinth seal, as the primary sealing structure, significantly reduces the pressure of the process gas discharged into the sealing cavity. The pre-exhaust port connects to the low-pressure nodes at the turbine expander's inlet and outlet, forming a loop. This not only recovers the high-pressure process gas from the sealing cavity to the circulation system but also significantly reduces the temperature and pressure inside the sealing cavity through the negative feedback of the loop. The pre-carbon floating ring and dry gas sealing body suppress leakage of process gas from the sealing cavity to the atmosphere, improving the working environment of the turbine expander dry gas sealing device, significantly reducing the technical requirements and construction costs of the sealing system, and improving the cost-effectiveness of dry gas sealing technology in small-to-medium scale applications.

[0036] Example 1

[0037] The following description uses a supercritical carbon dioxide centripetal turbine as an example to illustrate one technical solution of the present invention.

[0038] The dry gas seal body adopts a cartridge-type single-end face dry gas seal with a front carbon ring seal. As the main sealing device of the supercritical carbon dioxide radial turbine, the dry gas seal body is installed on one side of the impeller of the single-stage cantilever radial turbine (with a pulley seal auxiliary at the front end). The dry gas seal body is used for high temperature and high pressure carbon dioxide working fluid sealing, requiring a very small amount of process gas to leak into the atmosphere.

[0039] The pre-exhaust port is connected to the outlet of the radial turbine. After passing through the two-stage pre-exhaust carbon rings of the dry gas seal body, the sealing gas flow mixes with the high-temperature fluid (pressure greater than 11.5MPa, temperature about 450℃) leaking from the radial turbine. Under the action of pressure difference, it automatically flows back to the outlet pipeline of the radial turbine through the pre-exhaust port (without the need for external pump assistance).

[0040] The sealing gas source for the dry gas seal body is directly drawn from the outlet of the centrifugal compressor, with a pressure of approximately 18.29 MPa and a temperature of approximately 80°C. After filtration and pressure reduction (filtration accuracy of 1 micron), the pressure of the gas source is reduced to approximately 11.8–12.3 MPa, which is then used as the sealing gas for the dry gas seal device. The gas filling rate is not less than 50 Nm³ / h.

[0041] The dry gas seal body is bidirectionally rotatable and is used in supercritical carbon dioxide centrifugal turbines. The process gas is a high-temperature fluid leaking from the moving and stationary gaps of the centrifugal turbine (throttled by a Labridge seal). The process gas pressure is greater than 11.5 MPa, and the process gas temperature can reach up to 500℃. Based on experience in power machinery production and operation, the seal gas pressure must always be 0.2–0.3 MPa higher than the seal cavity (process gas) pressure.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1. Improving the cost-effectiveness of dry gas seals in small-to-medium-scale applications: The pre-exhaust port is connected to the low-pressure nodes at the inlet and outlet of the turbine expander to form a self-circulating loop. This self-circulating loop not only recovers the high-pressure process gas retained in the sealing cavity to the circulation system, but also significantly reduces the temperature and pressure of the process gas within the sealing cavity due to the negative feedback effect of the loop. This mitigates the damage to the dry gas seal body caused by the high-temperature and high-pressure environment, significantly reducing the technical requirements and construction costs of the turbine expander dry gas seal system. This improves the cost-effectiveness and market competitiveness of dry gas seal technology in small-to-medium-scale applications such as low-power supercritical fluid dynamics cycles, high-load compact turbine expanders, and weapon power platforms.

[0044] 2. Improve the heat resistance and service life of dry gas seals: The temperature of the sealing gas in the dry gas seal body is relatively low. After mixing with the high-temperature process gas leaking from the turbine expander, it can significantly reduce the temperature of the sealing cavity and the hot end face of the labyrinth seal. This weakens the effects of thermal stress, thermal alternating loads, and other factors on the device structure under high-temperature conditions, such as compression, damage, and creep. It also plays a role in cooling and heat protection for the high-temperature components of the sealing device, significantly enhancing the heat resistance of the dry gas seal device and improving its stability and service life in harsh environments such as high temperatures.

[0045] 3. Simplified Auxiliary Equipment and Control System of Dry Gas Sealing Device: The sealing gas flow from the dry gas sealing body passes through the pre-mounted carbon float ring of the device and mixes with the high-temperature, high-pressure process gas leaking into the sealing chamber from the turbine expander. Under the action of pressure difference, it automatically flows back to the low-pressure nodes of the turbine expander inlet and outlet pipelines through the pre-mounted exhaust port. Since the return process of process gas and sealing gas does not require external pump assistance, redundant auxiliary equipment and control mechanisms such as pneumatic gas booster pumps and return flow control elements can be omitted in the control system, greatly simplifying the auxiliary equipment and control system of the dry gas sealing device.

[0046] This invention reduces the damage to the dry gas seal body caused by high temperature and high pressure environments, improves the heat resistance and service life of the dry gas seal, simplifies the auxiliary equipment and control system of the dry gas seal device, and increases the cost-effectiveness of dry gas sealing technology in small and medium-scale application scenarios. It enables dry gas sealing technology to be widely used in space / cost-constrained, one-time / intermittent, deep space and deep sea and extreme harsh conditions and special scenarios with less sealing loss, thus expanding the application scenarios and technical competitiveness of dry gas sealing technology.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A self-circulating dry gas sealing device for a turbine expander, characterized in that, It includes a volute, impeller assembly, labyrinth seal (1), sealing cavity (2), front carbon float ring (4), and dry gas seal body (5); The impeller assembly is set in the volute of the mother machine. The labyrinth seal ring (1), the front carbon floating ring (4) and the dry gas sealing body (5) are coaxially sleeved on the impeller assembly and arranged in sequence from the working fluid side to the atmospheric side. A sealing cavity (2) is provided between the labyrinth seal ring (1) and the front carbon floating ring (4). The gap between the impeller assembly and the volute is connected to the inlet of the labyrinth seal ring (1). The labyrinth outlet of the labyrinth seal ring (1) is connected to the sealing cavity (2). A sealing gas pump hole (6) is provided on the volute. The sealing gas is pressurized and injected into the outer ring surface of the dry gas sealing body (5) through the pump hole (6). The inner ring surface of the dry gas sealing body (5) is connected to the sealing cavity (2) through the front carbon floating ring (4). The sealing cavity (2) is connected to the low-pressure node of the mother machine through a self-circulation loop. When the mother machine is a radial compressor, the compressor inlet serves as the low-pressure node of the self-circulating loop; When the mother machine is a radial flow turbine, the outlet of the radial flow turbine serves as the low-pressure node of the self-circulating loop. The volute is provided with a front exhaust port (3). One end of the front exhaust port (3) is connected to the sealing cavity (2), and the other end of the front exhaust port (3) is connected to the low-pressure node of the mother machine through a self-circulation loop. The front exhaust port (3) automatically reduces the temperature / pressure of the sealing cavity through loop negative feedback.

2. The self-circulating dry gas sealing device for a turbine expander according to claim 1, characterized in that, The impeller assembly includes an impeller nose cone (8), a turbine expander main shaft (9), and a radial impeller (10); The impeller assembly includes an impeller nose cone (8), a turbine expander main shaft (9), and a radial impeller (10). The impeller nose cone (8) is located at the end of the radial impeller (10) and close to the air inlet of the machine. The impeller nose cone (8) and the radial impeller (10) are coaxially connected by the turbine expander main shaft (9). The end of the turbine expander main shaft (9) extending out of the radial impeller (10) is connected to the main shaft of the motor through a drive shaft.

3. The self-circulating dry gas sealing device for a turbine expander according to claim 2, characterized in that, The end of the turbine expander main shaft (9) is connected to the generator main shaft via a drive shaft. The drive shaft is installed in the volute, and an atmospheric side brush seal (7) is provided at the end of the drive shaft near the atmosphere.

4. The self-circulating dry gas sealing device for a turbine expander according to claim 2, characterized in that, The radial impeller (10) includes an impeller body and a positioning post. One end of the impeller body is connected to a nose cone (8), and the positioning post is set at the other end of the impeller body. A sealing groove is provided on the volute. A labyrinth seal ring (1) is fitted on the positioning post and located in the sealing groove. A rotation gap is provided between the impeller body and the cold end face of the volute and the labyrinth seal ring (1). The rotation gap forms an airflow channel that connects to the labyrinth inlet of the labyrinth seal ring (1).

5. A self-circulating dry gas sealing device for a turbine expander according to claim 2, characterized in that, The sealing cavity (2) is an annular cavity, located outside the front carbon floating ring (4), and the front carbon floating ring (4) is connected to the sealing cavity (2).

6. The self-circulating dry gas sealing device for a turbine expander according to claim 1, characterized in that, A flow controller is installed on the self-circulating loop to control the return flow of the working fluid and adjust the pressure of the sealing cavity.

7. The self-circulating dry gas sealing device for a turbine expander according to claim 1, characterized in that, The air pump port (6) is connected to an air source, and the temperature of the sealing gas generated by the air source is lower than the working fluid temperature at the air inlet.

8. A self-circulating dry gas sealing device for a turbine expander according to claim 7, characterized in that, The pressure of the sealing gas is greater than the pressure of the sealing cavity.

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