Axial force balancing mechanism and turboexpander

Abstract

The application discloses an axial force balancing mechanism and a turbo expander. The axial force balancing mechanism is used for balancing the axial force of a turbo expander. The axial force balancing mechanism comprises a casing, a main shaft rotatably connected with the casing, the main shaft having an expansion end and a pressurization end, the expansion end being provided with a working wheel, and the pressurization end being provided with a pressurization wheel; a shaft sleeve fixed to the main shaft, the inner shaft sleeve being provided with a shaft sleeve sawtooth; and a sealing device connected with the casing and corresponding to the inner shaft sleeve, the sealing device being provided with a sealing sawtooth; wherein the tooth shapes of the shaft sleeve sawtooth and the sealing sawtooth are staggered. The axial force balancing mechanism and the turbo expander can realize the balance adjustment of the axial force of the expander.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas cryogenic separation and liquefaction, in particular to an axial force balancing mechanism and a turbo expander. BACKGROUND

[0002] The turbo expander is one of the key equipment in the low-temperature gas-liquid system. The main principle of the turbo expander is to use the gas with certain pressure energy to perform isentropic expansion through the turbo expander, so as to reduce the pressure energy of the gas, output mechanical energy, and generate refrigeration capacity. The output mechanical energy drives the booster fan, generator and other consumptions. The core component of the turbo expander is the rotor system, which is supported in the casing through bearings and rotated through a driving device (such as a motor or a turbine). The main function is to accelerate the gas and generate kinetic energy. The turbo expander has the working characteristics of high speed, low temperature and large pressure difference. The axial force in the turbo expander fluctuates in a large range, which has a great impact on the bearing. Due to the increase of the load and the temperature rise of the bearing, the wear is serious, which greatly shortens the service life of the bearing. Therefore, proper adjustment of the axial force directly affects the operating efficiency and service life of the turbo expander. At present, when the bearing capacity is large, the diameter of the bearing block is directly changed, and the diameter is increased. The disadvantage is that the oil consumption is large and the area is large.

[0003] At present, there is an urgent need for a method to efficiently and low-cost adjust the axial force. SUMMARY

[0004] The purpose of the present application is to provide an axial force balancing mechanism and a turbo expander, which can efficiently and low-cost adjust the axial force balance.

[0005] In a first aspect, the present application provides an axial force balancing mechanism for balancing the axial force of a turbo expander, the axial force balancing mechanism comprising a casing, comprising:

[0006] a main shaft rotatably connected to the casing, the main shaft having an expansion end and a booster end, the expansion end being provided with a working wheel, and the booster end being provided with a booster wheel;

[0007] a shaft sleeve fixed to the main shaft, the inner shaft sleeve being provided with a shaft sleeve sawtooth;

[0008] a sealing device connected to the casing and corresponding to the inner shaft sleeve, the sealing device being provided with a sealing sawtooth;

[0009] wherein the tooth shapes of the shaft sleeve sawtooth and the sealing sawtooth are staggered, and a barrier gas is provided between the shaft sleeve and the sealing device.

[0010] The expansion end is mainly responsible for expanding the gas and doing work. In this process, the volume of the gas increases, power is generated and work is output. The main task of the pressurization end is to increase the pressure of the gas. In this process, the flow rate of the gas increases and the pressure increases. Taking hydrogen as an example, the cooled hydrogen enters the pressurization end, changes from low-pressure normal-temperature hydrogen to high-pressure normal-temperature hydrogen, and then the hydrogen is re-pressurized. The high-pressure normal-temperature hydrogen passes through the expansion end and releases energy through expansion, and then changes to low-pressure low-temperature hydrogen. The low-temperature hydrogen is the product with cold energy.

[0011] During operation, because of the large temperature difference between the left and right ends and other factors, the axial force of the main shaft is unbalanced left and right, and the so-called axial force shifting problem may occur. Through the staggered arrangement of the teeth of the shaft sleeve and the seal, the oil circuit of the main shaft can be sealed by the barrier gas between the shaft sleeve and the seal, and when the main shaft is subjected to force deviation, the change of the gap between the teeth of the shaft sleeve and the seal can realize the change of the static pressure, forming a damping effect to adjust the force balance of the main shaft.

[0012] In combination with the first aspect, in a further implementation, the shaft sleeve includes an inner shaft sleeve and an outer shaft sleeve, the inner shaft sleeve is fixed to the expansion end of the main shaft and located between the working wheel and the pressurization wheel, and the seal includes an inner seal and an outer seal, the inner seal is connected with the machine shell and arranged correspondingly with the inner shaft sleeve.

[0013] By adopting the above technical solution, the inner shaft sleeve and the inner seal are installed at the expansion end of the main shaft, which can sensitively detect the changes of the axial and radial forces of the expansion end, and the change of the gap between the teeth of the shaft sleeve and the seal can synchronously realize the change of the static pressure, so as to quickly adjust the axial force balance of the main shaft.

[0014] In combination with the first aspect, in a further implementation, the outer shaft sleeve is fixed to the pressurization end of the main shaft and located between the pressurization wheel and the inner shaft sleeve, and the outer seal is connected with the machine shell and arranged correspondingly with the outer shaft sleeve.

[0015] By adopting the above technical solution, the outer shaft sleeve and the outer seal are installed at the pressurization end of the main shaft, which can sensitively detect the changes of the axial and radial forces of the pressurization end, and the change of the gap between the teeth of the shaft sleeve and the seal can synchronously realize the change of the static pressure, so as to quickly adjust the axial force balance of the main shaft.

[0016] In combination with the first aspect, in a further implementation, the distance from the tooth tip of the sawtooth of the shaft sleeve to the center of the main shaft gradually increases from the end of the main shaft to the center of the main shaft.

[0017] In combination with the first aspect, in a further implementation, the distance from the tooth tip of the sawtooth of the seal to the center of the main shaft gradually decreases from the end of the main shaft to the center of the main shaft.

[0018] In actual operation, the pressure in the tooth gap between the shaft sleeve and the seal is not completely uniform around the circumference, especially near the end of the main shaft. Since the gas just enters the tooth gap at this position, the uniformity of the pressure around the circumference is the most different, which can cause the radial force around the circumference to be different at the same axial position. When the main shaft is axially offset, the radial force of the shaft sleeve is often large. After the radial force around the circumference is unbalanced, a radial offset load is generated, which can increase the load of the bearing and affect the service life of the bearing.

[0019] By adopting the above technical scheme, the smaller the outer diameter of the shaft sleeve sawtooth at the end of the main shaft, the larger the outer diameter of the sealing sawtooth, and the larger the gap between the shaft sleeve sawtooth and the sealing sawtooth, the smaller the stress area of the static pressure around the circumference. In the case of the same pressure but smaller stress area, the radial force of a single tooth is smaller. Thus, when the gas just enters the tooth gap, the uniformity of the pressure around the circumference can be reduced, the unbalance of the radial force around the circumference of the shaft sleeve can be reduced, the radial offset load of the shaft sleeve can be reduced, and the service life of the main shaft and the bearing can be improved. The outer diameter of the shaft sleeve sawtooth near the center of the main shaft is large, the outer diameter of the sealing sawtooth is small, and the gap between the shaft sleeve sawtooth and the sealing sawtooth is small. When the main shaft is displaced, the fluid static pressure can be quickly generated between the shaft sleeve sawtooth and the sealing sawtooth to balance and adjust the force of the main shaft.

[0020] In combination with the first aspect, in a further implementation, the tooth spacing of the shaft sleeve sawtooth gradually decreases from the end of the main shaft to the center of the main shaft.

[0021] In combination with the first aspect, in a further implementation, the tooth spacing of the sealing sawtooth gradually decreases from the end of the main shaft to the center of the main shaft.

[0022] By adopting the above technical scheme, the larger the tooth spacing of the shaft sleeve sawtooth and the sealing sawtooth at the end of the main shaft, the larger the gap between the shaft sleeve sawtooth and the sealing sawtooth, the smaller the stress area of the static pressure around the circumference. In the case of the same pressure but smaller stress area, the radial force of a single tooth is smaller. Thus, when the gas just enters the tooth gap, the uniformity of the pressure around the circumference can be reduced, the unbalance of the radial force around the circumference of the shaft sleeve can be reduced, the radial offset load of the shaft sleeve can be reduced, and the service life of the main shaft and the bearing can be improved. The tooth spacing of the shaft sleeve sawtooth and the sealing sawtooth near the center of the main shaft is small, and the gap between the shaft sleeve sawtooth and the sealing sawtooth is small. When the main shaft is displaced, the fluid static pressure can be quickly generated between the shaft sleeve sawtooth and the sealing sawtooth to balance and adjust the force of the main shaft.

[0023] In combination with the first aspect, in a further implementation, the seal is provided with a gas supplement port, the gas supplement port is located on the side of the seal near the end of the main shaft, and a buffer zone is arranged between the gas supplement port and the shaft sleeve near the center of the main shaft.

[0024] By adopting the technical scheme, the air supplement port is arranged on the side close to the end of the main shaft, which can supplement the barrier air between the sawtooth of the shaft sleeve and the sealing sawtooth, increase the air pressure in the sawtooth gap, increase the leakage prevention effect, and improve the balance adjustment function of the axial force. When the main shaft with the shaft sleeve is offset in the axial direction, the gap in the sawtooth combination between the sawtooth of the shaft sleeve and the sealing sawtooth changes, the static pressure changes, and a damping effect is formed. The greater the air pressure, the stronger the damping effect. In the scheme, the air supplement port is a channel for supplementing the barrier air, and when the axial displacement of the main shaft occurs, the barrier air can be directly supplemented to form a high-damping effect of high air pressure. The buffer area is arranged between the air supplement port and the shaft sleeve on the side close to the center of the main shaft, the tooth spacing can be additionally enlarged to form a local buffer area, and the main purpose of the local buffer area is to balance the air pressure, so that the air entering the air supplement port flows more smoothly to the center of the main shaft, which is beneficial to forming a high-damping effect between all tooth spacings.

[0025] In combination with the first aspect, in a further aspect, a sensor is arranged at the expansion end and / or the pressurization end, the sensor is used to detect temperature, pressure and flow, the sensor is connected with a control valve, and the control valve adjusts the pressure difference between the two ends of the main shaft to 1.5 times according to the feedback of the sensor to achieve balance.

[0026] By adopting the technical scheme, the temperature, pressure and flow at the two ends of the inlet are detected by the sensor, so that the oil supply pressure of the oil supply port is regulated. The specific regulation model is as follows: if one end receives a larger force, the main shaft usually offsets to the end receiving the larger force to resist the imbalance caused by the force, at this time, the control valve supplies oil to the end receiving the larger force, and the thrust of the end receiving the larger force is increased, so that the pressure difference between the two ends is 1.5 times, the main shaft is offset to the end, and the balance effect is achieved.

[0027] In the second aspect, the application provides a turbo expander comprising the axial force balance mechanism of the first aspect.

[0028] By adopting the technical scheme, the turbo expander with the axial force balance mechanism can balance the force balance of the main shaft, thereby reducing the failure rate and prolonging the service life of the product.

[0029] In summary, the application has at least one of the following beneficial technical effects:

[0030] 1. The axial force balance mechanism of the application has a simple structure, small changes to the existing structure, and is easy to upgrade.

[0031] 2. The axial force balance mechanism of the application can realize automatic balance adjustment of the force of the main shaft.

[0032] 3. The turbo expander of the application can balance the force balance of the main shaft, thereby reducing the failure rate and prolonging the service life of the product. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is the structural schematic diagram of the first embodiment of the axial force balance mechanism of the present application;

[0034] Figure 2 is the main shaft assembly structural schematic diagram of the first embodiment of the axial force balance mechanism of the present application;

[0035] Figure 3 is the force schematic diagram of the working wheel of the first embodiment of the axial force balance mechanism of the present application;

[0036] Figure 4 is the cross-sectional schematic diagram of the inner shaft sleeve of the first embodiment of the axial force balance mechanism;

[0037] Figure 5 is the structural schematic diagram of the cooperation of the inner shaft sleeve and the inner seal of the first embodiment of the axial force balance mechanism;

[0038] Figure 6 is the cooperation schematic diagram of the shaft sleeve serration of the inner shaft sleeve and the sealing serration of the inner seal of the first embodiment of the axial force balance mechanism;

[0039] Figure 7 is the force analysis schematic of the shaft sleeve serration and the sealing serration of the first embodiment of the axial force balance mechanism;

[0040] Figure 8 is the schematic diagram of the second embodiment of the axial force balance mechanism of the present application.

[0041] Reference signs:

[0042] 1, housing; 2, main shaft; 21, expansion end; 211, working wheel; 22, pressure boosting end; 221, pressure boosting wheel; 3, shaft sleeve; 31, inner shaft sleeve; 311, shaft sleeve serration; 32, outer shaft sleeve; 4, seal; 41, inner seal; 411, air supplement port; 412, sealing serration; 42, outer seal; 5, bearing; 51, inner bearing; 52, outer bearing; 6, sensor; 61, temperature sensor; 62, pressure sensor; 63, flow sensor; 7, control valve. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the present application will be further described in detail below with reference to the drawings. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present application.

[0044] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0047] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments can be combined with each other.

[0048] Example 1

[0049] Please see Figure 1 and Figure 2 This embodiment discloses an axial force balancing mechanism for balancing the axial force of a turbine expander. The axial force balancing mechanism includes a housing 1, a main shaft 2, a bushing 3, and a seal 4. The main shaft 2 is rotatably connected to the housing 1 and has an expansion end 21 and a pressure boosting end 22. The expansion end 21 is equipped with a working wheel 211, and the pressure boosting end 22 is equipped with a pressure boosting wheel 221. The bushing 3 is connected to the main shaft 2 by an interference fit, and the seal 4 is connected to the housing 1 and corresponds to the inner bushing 31.

[0050] The bushing 3 includes an inner bushing 31 and an outer bushing 32. The inner bushing 31 is fixed to the expansion end 21 of the main shaft 2 and is located between the working wheel 211 and the pressure wheel 221. The seal 4 includes an inner seal 41 and an outer seal 42. The inner seal 41 is connected to the housing 1 and is correspondingly arranged with the inner bushing 31. The outer bushing 32 is fixed to the pressure end 22 of the main shaft 2 and is located between the pressure wheel 221 and the inner bushing 31. The outer seal 42 is connected to the housing 1 and is correspondingly assembled with the outer bushing 32.

[0051] Please see Figure 1, the left side of the axial force balance mechanism is the expansion end 21, and the right side is the pressurization end 22. Taking hydrogen as an example, the hydrogen to be cooled enters the pressurization end 22 at the far right, changes from low-pressure normal-temperature hydrogen to high-pressure normal-temperature hydrogen, and then the hydrogen is re-pressurized. The high-pressure normal-temperature hydrogen then passes through the expansion end 21, releases energy through expansion, and changes to low-pressure low-temperature hydrogen. The low-temperature hydrogen is the product with cold energy.

[0052] After expansion, the expansion end 21 drives the main shaft 2 to rotate through the working wheel 211, and the rotating main shaft 2 provides power for the pressurization end 22. The energy for hydrogen pressurization does not come entirely from the pressurization end 22, but there is also secondary pressurization.

[0053] During operation, the temperature difference between the left and right ends is large, causing the axial force of the main shaft 2 to be unbalanced left and right, resulting in axial movement. Currently, this problem is mainly solved by using a thrust bearing 5. The thrust bearing 5 is fixed in the casing 1, and the main shaft 2 passes through the thrust bearing 5. The thrust pad is used to abut against the end face of the middle shaft shoulder of the main shaft 2. There are thrust bearings 5 on both the left and right ends, so the main shaft 2 can be limited in both left and right directions.

[0054] Please refer to Figure 2 , the expansion end 21 of the main shaft 2 is fixedly assembled with a working wheel 211. An inner shaft sleeve 31 and an inner bearing 51 are sequentially assembled from the expansion end 21 to the center of the main shaft 2, and an inner sealing device 41 is connected with the inner shaft sleeve 31. The pressurization end 22 of the main shaft 2 is fixedly assembled with a pressurization wheel 221. An outer shaft sleeve 32 and an outer bearing 52 are sequentially assembled from the pressurization end 22 to the center of the main shaft 2, and an outer sealing device 42 is connected with the outer shaft sleeve 32. The inner bearing 51 and the outer bearing 52 abut against the two end faces of the shaft shoulder in the middle of the main shaft 2, and are used to resist the axial movement of the main shaft 2. The connection between the inner sealing device 41 and the inner shaft sleeve 31 and the connection between the outer sealing device 42 and the outer shaft sleeve 32 can not only achieve oil sealing but also balance the unbalanced force caused by the axial movement of the main shaft 2, reduce the stress on the inner bearing 51 and the outer bearing 52, and prolong the service life of the inner bearing 51 and the outer bearing 52.

[0055] Please refer to Figure 3 , the axial force of the working wheel in the turbine expander is as follows: the axial force on the working wheel includes the gas pressure F1 in the gap on the back of the wheel disc, the gas pressure F2 in the gap on the top side of the working wheel, the gas pressure F3 on the cross section of the exhaust port, the gas pressure F4 on the hub face, and the reaction force Fc2 when the gas is discharged. Therefore, the total axial force F a =F1-F2-F3-F4-Fc2, where:

[0056]

[0057] If the density p and the discharge velocity c 2mand the directional angle α2 is expressed by an average value, then

[0058] Gas pressure F = ∫2πrp(r)dr

[0059] The pressure distribution p(r) in the radial direction is determined by experiment, and thus,

[0060]

[0061]

[0062]

[0063]

[0064] When the exhaust gas pressure is expressed by an average pressure, then

[0065]

[0066] Referring to Figure 1 and Figure 3 The load of the thrust bearing 5 is mainly axial force, and the balance of the shaft 2 and the two parts of the expansion end 21 and the pressurization end 22 is adjusted according to the changes and directions of the thrusts of the two parts.

[0067] Referring to Figure 2 and Figure 4 The inner sleeve 31 is provided with sleeve saw teeth 311, and the distance from the tooth tips of the sleeve saw teeth 311 to the shaft center of the shaft 2 gradually increases from the end of the shaft 2 to the center of the shaft 2. In this embodiment, the tooth tips of all the sleeve saw teeth 311 are connected to form a slanted line inclined to the shaft center of the shaft 2, and in practice, the connecting line of the tooth tips of all the sleeve saw teeth 311 can also be a curve.

[0068] Alternatively, the distance from the tooth tips of the sleeve saw teeth 311 to the shaft center of the shaft 2 gradually increases from the end of the shaft 2 to the center of the shaft 2, and the interval between the teeth of the sleeve saw teeth 311 gradually decreases from the end of the shaft 2 to the center of the shaft 2.

[0069] Referring to Figure 2 and Figure 5, the gas barrier is set between the shaft sleeve 3 and the seal 4. The seal 4 is provided with a gas supplement port 411, which is located on the side of the seal 4 close to the end of the main shaft 2. The gas supplement port 411 and the shaft sleeve 3 are provided with a buffer zone close to the center of the main shaft 2. Taking the inner seal 41 as an example, the gas supplement port 411 is located on the side of the inner seal 41 close to the end of the main shaft 2. The gas supplement port 411 will supplement gas to improve the sealing performance and the balance of the axial force. A relatively large space is left between the gas supplement port 411 and the inner shaft sleeve 31 for the buffer of the gas entering, that is, the tooth spacing is appropriately enlarged on the side of the gas supplement port 411 close to the center of the main shaft 2. When the gas enters the gap between the inner shaft sleeve 31 and the inner seal 41 from the gas supplement port 411, the gas pressure is balanced and the impact is reduced.

[0070] The seal 4 can be assembled by splitting and splicing. For example, the inner seal 41 can be spliced into one whole body by two parts, three parts or four parts. When assembling, the inner shaft sleeve 31 is first assembled with the main shaft 2, then the inner seal 41 is spliced and assembled with the inner shaft sleeve 31, and finally the main shaft 2, the inner shaft sleeve 31 and the inner seal 41 are assembled as a whole with the casing 1. This splicing scheme can facilitate the assembly of the technical scheme in which the seal sawtooth 412 and the shaft sleeve sawtooth 311 intersect each other close to the center of the main shaft 2.

[0071] Please refer to Figure 6 The seal 4 is provided with seal sawtooth 412, the tooth shape of the shaft sleeve sawtooth 311 and the seal sawtooth 412 is staggered, and the gas barrier is set between the shaft sleeve 3 and the seal 4. The distance from the tooth tip of the seal sawtooth 412 to the center of the main shaft 2 gradually decreases from the end of the main shaft 2 to the center of the main shaft 2, and the tooth spacing of the seal sawtooth 412 gradually decreases from the end of the main shaft 2 to the center of the main shaft 2.

[0072] Taking the inner seal 41 and the inner shaft sleeve 31 as an example, the seal sawtooth 412 of the inner seal 41 is located between the two teeth of the shaft sleeve sawtooth 311 of the inner shaft sleeve 31, the seal sawtooth 412 and the shaft sleeve sawtooth 311 are oppositely arranged, and the seal sawtooth 412 and the shaft sleeve sawtooth 311 are correspondingly staggered, forming a working gap therebetween. The working gap can form a labyrinth seal and realize self-balancing adjustment when the gap between the seal sawtooth 412 and the shaft sleeve sawtooth 311 changes when the main shaft 2 axially moves.

[0073] In this embodiment, the tooth spacing of the shaft sleeve sawtooth 311 and the sealing sawtooth 412 near the end of the main shaft 2 is large, and the outer diameter of the shaft sleeve sawtooth 311 is small and the outer diameter of the sealing sawtooth 412 is large, so the gap between the shaft sleeve sawtooth 311 and the sealing sawtooth 412 near the end of the main shaft 2 is large and the static pressure is small. From the end of the main shaft 2 to the center of the main shaft 2, the tooth spacing of the shaft sleeve sawtooth 311 gradually decreases and the outer diameter gradually increases, and the tooth spacing of the sealing sawtooth 412 gradually decreases and the outer diameter gradually decreases, so the gap between the shaft sleeve sawtooth 311 and the sealing sawtooth 412 gradually decreases from the end of the main shaft 2 to the center of the main shaft 2.

[0074] Please refer to Figure 2 , Figure 6 and Figure 7 In actual work, the pressure in the gap between the shaft sleeve sawtooth 311 and the sealing sawtooth 412 is not completely uniform, especially near the entrance at the end of the main shaft 2. The uniformity of the circumferential pressure is the most different here, which will cause the radial component of the circumferential static pressure at the same point to be different. When the main shaft 2 is axially offset, the radial component is large, and after the circumferential radial component is unbalanced, a radial offset load is generated, which will increase the load carrying capacity of the bearing 5 and affect its service life. The principle of setting the tooth spacing is that when the main shaft 2 is axially offset by the same distance, the larger the tooth spacing of the shaft sleeve sawtooth 311, the larger the gap spacing at the static pressure, the smaller the static pressure, and the smaller the radial component of the main shaft 2, the smaller the radial load on the bearing 5. The principle of setting the outer diameter is that the smaller the outer diameter of the shaft sleeve sawtooth 311, the smaller the static pressure force area of one revolution, and the smaller the radial component of the individual tooth under the same pressure.

[0075] In the process of blocking gas from entering the gap between the shaft sleeve sawtooth 311 and the sealing sawtooth 412 at the end of the main shaft 2, the static pressure at the entrance is small, which facilitates the entry of the blocked gas, and the static pressure gradually increases towards the center of the main shaft 2, which can make the pressure change more uniform during the axial force balance adjustment of the main shaft 2 during movement, and realize gradual progressive change.

[0076] Example Two

[0077] Please refer to Figure 8 The difference between this embodiment and Example One is that the expansion end 21 and the pressurization end 22 are provided with a sensor 6 for detecting the temperature, pressure and flow rate at the entrances at both ends of the main shaft 2. The sensor 6 is connected with a control valve 7, the control valve 7 is connected with a power mechanism, and the control valve 7 is connected with the inner bearing 51 and the outer bearing 52 at both ends, respectively. The control valve 7 adjusts the gas pressure or oil pressure at both ends of the main shaft 2 according to the feedback of the sensor 6, so that the pressure difference at both ends of the main shaft 2 is 1.5 times, so as to achieve balance.

[0078] Specific regulation principle is: if one end of the main shaft 2 is larger, the main shaft 2 will offset to the other end, to resist the imbalance caused by force, at this time need to the other end of the oil or gas, by increasing the other end of the thrust, the pressure difference between both ends to 1.5 times, the main shaft 2 to the force of one end, to achieve the effect of balance. For example: if the expansion end 21 of the force is larger, the main shaft 2 will move to the boost end 22, at this time sensor 6 detection according to the expansion end 21 or boost end 22 temperature, pressure and flow changes feedback to the control valve 7, control valve 7 to the boost end 22 oil or gas to increase the thrust of the boost end 22, realize the balance of the main shaft 2 force.

[0079] The sensor 6 is arranged on the expansion end 21 and the boost end 22, which is the optimal embodiment. In the actual implementation process, the sensor 6 can be arranged on the expansion end 21 or the boost end 22 according to the actual working condition to detect the temperature, pressure and flow of one end and feedback to the control valve 7 for pressure balance adjustment.

[0080] Embodiment three

[0081] The embodiment discloses a kind of turbine expanders, including the axial force balance mechanism in embodiment one or embodiment two.

[0082] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, the present application can have various changes, modifications, replacements and variations, which fall within the scope of the claimed present application.

Claims

1. An axial force balancing mechanism for balancing the axial forces of a turboexpander, said axial force balancing mechanism comprising a casing (1), characterized in that, The utility model relates to a kind of axial force balancing mechanism, including: Main shaft (2), rotatory connection with the shell (1), the main shaft (2) has expansion end (21) and booster end (22), the working wheel (211) is installed in the expansion end (21), the booster wheel (221) is installed in the booster end (22); Shaft sleeve (3), fixed on the main shaft (2), the shaft sleeve (3) is equipped with shaft sleeve sawtooth (311); Sealer (4), connection with the shell (1) and with the shaft sleeve (3) correspond, the sealer (4) is equipped with sealing sawtooth (412); Wherein, the tooth shape of the shaft sleeve sawtooth (311) and the sealing sawtooth (412) is staggered, and barrier gas is provided between the shaft sleeve (3) and the sealer (4); The sealer (4) is equipped with air supplement port (411), the air supplement port (411) is located in the sealer (4) near the main shaft (2) end portion side, and the air supplement port (411) and the shaft sleeve (3) are located near the main shaft (2) center side with buffer zone; The distance from the tooth tip of the shaft sleeve sawtooth (311) to the main shaft (2) center gradually increases from the end of the main shaft (2) to the center of the main shaft (2); The distance from the tooth tip of the sealing sawtooth (412) to the main shaft (2) center gradually decreases from the end of the main shaft (2) to the center of the main shaft (2); The tooth spacing of the shaft sleeve sawtooth (311) gradually decreases from the end of the main shaft (2) to the center of the main shaft (2); The tooth spacing of the sealing sawtooth (412) gradually decreases from the end of the main shaft (2) to the center of the main shaft (2).

2. The axial force balancing mechanism of claim 1, wherein, The shaft sleeve (3) includes inner shaft sleeve (31) and outer shaft sleeve (32), the inner shaft sleeve (31) is fixed on the expansion end (21) of the main shaft (2) and is located between the working wheel (211) and the booster wheel (221);The sealer (4) includes inner sealer (41) and outer sealer (42), and the inner sealer (41) is connected with the shell (1) and is correspondingly provided with the inner shaft sleeve (31).

3. The axial force balancing mechanism of claim 2, wherein, The outer shaft sleeve (32) is fixed on the booster end (22) of the main shaft (2) and is located between the booster wheel (221) and the inner shaft sleeve (31), and the outer sealer (42) is connected with the shell (1) and is correspondingly provided with the outer shaft sleeve (32).

4. The axial force balancing mechanism according to any one of claims 1-3, characterized in that, Sensor (6) is provided in the expansion end (21) and / or the booster end (22), the sensor (6) is used to detect temperature, pressure and flow, the sensor (6) is connected with control valve (7), the control valve (7) is adjusted according to the feedback of the sensor (6) to make the pressure difference of the two ends of the main shaft (2) 1.5 times, to achieve balance.

5. A turboexpander characterized by, The axial force balancing mechanism of any one of claims 1-4 is included.

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