Low temperature turboexpander

Abstract

The application relates to the technical field of low-temperature refrigeration, in particular to a low-temperature turboexpander. The low-temperature turboexpander comprises an integrated expansion volute, a fan volute connected with the expansion volute and a main machine arranged in the expansion volute, an end plate of the expansion volute and the fan volute is fixed to an external cold box, so that the expansion volute and the main machine are completely located in the cold box, the main machine comprises a main unit and a secondary unit which are integrally assembled and detachably connected with each other, the main unit is related to the shaft power grade of the turboexpander, and the secondary unit is related to the design requirement of the turboexpander. The technical scheme can effectively guarantee the assembly precision, reduce the heat leakage to the outside and improve the production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-temperature refrigeration, and in particular to a low-temperature turboexpander. BACKGROUND

[0002] The low-temperature turboexpander is a device that utilizes high-pressure working medium to expand and do work on the outside, while consuming the internal energy of the working medium, so as to cool the working medium and provide cold energy. It can be divided into three parts: one is the expansion side that realizes the expansion and cooling of the working medium, the second is the fan side that is used for power consumption, and the third is the machine body part that provides support and thermal insulation. The low-temperature turboexpander widely used in the hydrogen liquefaction system is mainly a helium turboexpander and a hydrogen turboexpander, which often works below the liquid nitrogen temperature zone.

[0003] However, the low-temperature turboexpander used in the hydrogen liquefaction system has the following problems: 1) it has a high requirement for assembly accuracy, so it is necessary to strictly control the assembly gap between its related parts; 2) since it often works below the liquid nitrogen temperature zone, the temperature difference with the outside environment is large, so it has a large heat leakage to the outside; and 3) since it has a high requirement for assembly accuracy, for different design requirements of the low-temperature turboexpander, it is often necessary to carry out targeted design for the whole set of parts, which will lead to a decrease in production efficiency.

[0004] Therefore, there is an urgent need to provide a new low-temperature turboexpander to solve the above technical problems. SUMMARY

[0005] The embodiment of the present application provides a low-temperature turboexpander, which can effectively ensure the assembly accuracy, reduce the heat leakage to the outside, and improve the production efficiency.

[0006] The embodiment of the present application provides a low-temperature turboexpander, which comprises an integrated expansion volute, a fan volute connected with the expansion volute, and a main machine arranged in the interior of the expansion volute. The end plate of the expansion volute and the fan volute is fixed to an external cold box, so that the expansion volute and the main machine are completely located in the interior of the cold box. The main machine comprises a main unit and a secondary unit which are integrally assembled and detachably connected with each other. The main unit is related to the shaft power level of the turboexpander, and the secondary unit is related to the design requirement of the turboexpander.

[0007] Compared with the related art, the present application has at least the following beneficial effects:

[0008] The low-temperature turboexpander provided by the embodiment of the present application can reduce the machining tolerance requirement of the expansion volute by installing the main machine integrally into the expansion volute, thereby reducing the assembly difficulty; the heat conduction length can be prolonged by locating the expansion volute and the main machine inside the cold box, thereby reducing the heat dissipation to the outside; the same main unit can be used for the turboexpander of the same shaft power level, and only the sub-unit of different design requirements needs to be replaced, thereby improving the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0010] Figure 1 The structure schematic diagram of the low-temperature turboexpander provided by the embodiment of the present application is shown in FIG. 1.

[0011] Figure 2 The cross-sectional schematic diagram of the low-temperature turboexpander shown in FIG. 1 after being installed into the cold box is shown in FIG. 2. Figure 1

[0012] The cross-sectional schematic diagram of the expansion volute in the low-temperature turboexpander shown in FIG. 1 is shown in FIG. 3. Figure 3 Figure 2 The cross-sectional schematic diagram of the main machine in the low-temperature turboexpander shown in FIG. 1 is shown in FIG. 4.

[0013] Figure 4 Figure 5 The cross-sectional schematic diagram of the main unit in the low-temperature turboexpander shown in FIG. 1 is shown in FIG. 5. Figure 2

[0014] Figure 6 Figure 2

[0015] Reference signs:

[0016] 1-expansion volute; 11-end plate; 12-screw; 13-inlet pipeline; 14-exhaust pipeline; 2-fan volute; 21-mounting position; 3-main machine; 31-main unit; 311-main shaft; 312-positioning ring; 313-bearing; 314-thermal insulation part; 315-cover plate; 316-first sealing part; 32-sub-unit; 321-expansion impeller; 322-nozzle ring; 323-expansion component; 324-fan impeller; 325-second sealing part; 326-nut; 4-cold box. DETAILED DESCRIPTION

[0017] ​​​​​In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0018] As shown in Figures 1 to 6 The embodiment of the present application provides a low-temperature turboexpander, which comprises an integrated expansion volute 1, a fan volute 2 connected with the expansion volute 1, and a main machine 3 arranged in the expansion volute 1. An end plate 11 connected with the expansion volute 1 and the fan volute 2 is fixed to an external cold box 4, so that the expansion volute 1 and the main machine 3 are completely located in the internal of the cold box 4. The main machine 3 comprises a main unit 31 integrally assembled and a secondary unit 32 detachably connected with the main unit 31. The main unit 31 is related to the shaft power level of the turboexpander, and the secondary unit 32 is related to the design requirement of the turboexpander.

[0019] In the embodiment, by integrally installing the main machine 3 into the integrated expansion volute 1, the machining tolerance requirement of the expansion volute 1 can be reduced, so as to reduce the assembly difficulty. By completely locating the expansion volute 1 and the main machine 3 in the internal of the cold box 4, the heat conduction length can be prolonged, and the heat leakage to the external can be reduced. By arranging the integrally assembled main unit 31, the same main unit 31 can be used for the turboexpanders with the same shaft power level, and only the secondary unit 32 with different design requirements needs to be replaced, so that the production efficiency can be improved.

[0020] It should be noted that the main machine 3 can be installed in the expansion volute 1, which is mainly used for the inlet and outlet flow channels of the expanded working medium and the inlet and outlet flow channels of the process gas, and the installation of the cold box 4. The fan volute 2 is connected with the main machine 3, which is mainly used for the inlet and outlet flow channels of the braking working medium, and is installed on the expansion volute 1 and does not directly contact the main machine 3.

[0021] In some embodiments, the end plate 11 can be fixed to the cold box 4 by welding.

[0022] In an embodiment of the present application, the design requirement includes the temperature, pressure and flow of the expanded working medium.

[0023] In the related art, the low-temperature turboexpander for the hydrogen liquefaction system has high requirements on the machining precision and assembly gap. For the hydrogen turboexpanders with different design requirements, the targeted design of the whole set of parts needs to be carried out again, and some parts need to be machined in coordination. At the same time, for the application requirement of the hydrogen liquefaction system, only a few turboexpanders of the same kind are needed, which cannot form a large-scale demand, so that it is difficult to realize batch production and high-efficiency production, and the production and assembly costs are high.

[0024] In order to solve the technical problem, the bearing 313 and the main shaft 311 are integrally assembled (i.e., the main unit 3131 is in an integrally assembled form), in the industrial production process, the same bearing-main shaft components can be used for the turbo expanders with the same shaft power level, and for the turbo expanders facing different design requirements, only the expansion impeller 321, the nozzle ring 322, the expansion component 323 and the fan impeller 324 need to be replaced according to different design parameters, so that different turbo expanders can be produced, and the production efficiency can be greatly improved and the production cost can be reduced.

[0025] Please continue to refer to Figure 5 In an embodiment of the present application, the main unit 31 comprises the main shaft 311, the positioning ring 312 arranged outside the main shaft 311, the two bearings 313 fixedly connected with the positioning ring 312, the heat insulation member 314 arranged outside one of the bearings 313, and the cover plate 315 fixedly connected with the other bearing 313, the heat insulation member 314 is located at the expansion side, the cover plate 315 is fixedly connected with the end plate 11, and the first sealing member 316 is arranged between the bearing 313 and the expansion volute 1.

[0026] In the embodiment, the two bearings 313 are installed together with the positioning ring 312, for providing support for the main shaft 311; the positioning ring 312 is installed between the two bearings 313, for controlling the spacing between the two bearings 313; the main shaft 311 is installed inside the two bearings 313, for installing the expansion impeller 321 and the fan impeller 324 and rotating at high speed; the expansion component 323 is in contact with the inlet and outlet air faces of the expansion volute 1, and the inlet and outlet air flow channels are sealed by the first sealing member 316, so as to avoid the inlet and outlet air flow from being communicated; the cover plate 315 is connected with the bearing 313, for fixing the bearing 313 and forming a labyrinth seal with the main shaft 311, so as to reduce the leakage from the fan side to the bearing side.

[0027] In an embodiment of the present application, the auxiliary unit 32 comprises the expansion impeller 321 arranged on the main shaft 311, the nozzle ring 322 and the expansion component 323 fixedly connected with the heat insulation member 314, and the fan impeller 324 arranged on the main shaft 311, the nozzle ring 322 and the expansion component 323 form an expansion working medium flow channel, the expansion component 323 and the expansion volute 1 have a first installation gap, the expansion component 323 and the expansion impeller 321 have a second installation gap, and the second sealing member 325 is arranged on the inner and outer sides of the expansion component 323.

[0028] In the embodiment, the expansion component 323 is connected to the main machine 3, so that the first installation gap between the expansion component 323 and the expansion impeller 321 is ensured, the assembly difficulty is reduced, and the gap and efficiency under the low-temperature working condition are ensured; the nozzle ring 322 is installed in the inner hole of the expansion-side heat-insulating piece 314, and is used for making the expansion working medium enter uniformly and expand and cool; the expansion component 323 is installed in the inner hole of the heat-insulating piece 314, is attached to the nozzle ring 322, and is fixed on the heat-insulating piece 314, so that the second installation gap between the expansion component 323 and the expansion impeller 321 is formed, the leakage amount of the expansion working medium is reduced under the premise that the main shaft 311 can rotate normally, and the working efficiency of the turbine is ensured; the heat-insulating piece 314 is installed on the bearing 313, and is used for reducing the heat conduction and leakage from the expansion side to the fan side; the expansion impeller 321 is installed on the main shaft 311, cooperates with the expansion component 323, the expansion working medium flows into the expansion impeller 321 through the nozzle ring 322, drives the expansion impeller 321 to rotate, and the working medium expands and cools; and the fan impeller 324 is installed on the main shaft 311, cooperates with the fan volute 2, makes the working medium work and adjusts the rotating speed.

[0029] In an embodiment of the present application, the fan volute 2 and the end plate 11, the cover plate 315 and the bearing 313, the cover plate 315 and the end plate 11, the bearing 313 and the positioning ring 312, and the expansion impeller 321, the nozzle ring 322 and the heat-insulating piece 314 are fixedly connected through the screws 12.

[0030] In the embodiment, all the structures are fastened and connected through the screws 12, and are then installed in the expansion volute 1, so that the machining tolerance requirement of the expansion volute 1 is greatly reduced, the key gap is ensured, and the assembly difficulty is reduced; the cover plate 315 is connected to the expansion volute 1 through the screws 12, so that the main machine 3 is ensured to be installed on the expansion volute 1, and the first installation gap between the expansion component 323 and the expansion volute 1 is ensured.

[0031] In an embodiment of the present application, the heat-insulating piece 314 and the main shaft 311 and the cover plate 315 and the main shaft 311 form the labyrinth seal.

[0032] In the embodiment, the labyrinth seal formed by the heat-insulating piece 314 and the main shaft 311 is used for reducing the leakage of the expansion-side cold gas to the bearing side, and the labyrinth seal formed by the cover plate 315 and the main shaft 311 is used for fixing the position of the bearing 313 and reducing the leakage of the fan-side hot gas to the bearing side.

[0033] In an embodiment of the present application, the expansion volute 1 is provided with the process gas inlet pipeline 13 and the exhaust pipeline 14, and the process gas can enter the outer periphery of the bearing 313 and the labyrinth seal.

[0034] In the embodiment, the process gas includes sealing gas and bearing gas, the bearing gas can enter the outer periphery of the bearing 313 to form a gas bearing, and the sealing gas can enter the labyrinth seal to complete the isolation of cold gas and hot gas and further reduce the leakage amount; the expansion volute 1 adopts a host machine shell-free design, the host machine 3 is directly integrated on the bearing 313, and the expansion volute 1 is extended, so that the expansion volute 1 has the functions of expansion working medium inlet and outlet gas and bearing gas, sealing gas and the like, the integral assembly of the host machine 3 is realized, and the assembly difficulty is reduced.

[0035] In an embodiment of the application, the expansion impeller 321 and the fan impeller 324 are fixed on the main shaft 311 through the nut 326, the fan volute 2 is provided with a mounting position 21 for mounting a rotation speed sensor and a displacement sensor, the rotation speed sensor is used to measure the rotation speed of the main shaft 311, and the displacement sensor is used to measure the displacement of the main shaft 311.

[0036] In some embodiments, the bearing 313 can be a static pressure gas bearing or a dynamic pressure gas bearing.

[0037] In some embodiments, the main shaft 311 can be a single thrust disc structure or a double thrust disc structure.

[0038] In some embodiments, the first sealing element 316 can be a Teflon gasket or an O-ring, and the second sealing element 325 can be a generic seal, a red copper gasket, a trifluoro gasket or a Teflon gasket.

[0039] In some embodiments, the rotation speed sensor can be an optical sensor or an electromagnetic sensor.

[0040] Please continue to refer to Figure 3 and Figure 4 In an embodiment of the application, along the axial direction of the main shaft 311, the first mounting gap cannot exceed 0.2 mm, and the first mounting gap is determined by the following formula:

[0041] a-e-f-a1

[0042] In the formula, a is the outer thickness of the heat insulation element 314, e is the thickness of the expansion component 323, f is the thickness of the nozzle ring 322, and a1 is the bottom thickness of the heat insulation element 314.

[0043] In the embodiment, to smoothly realize the function of the turbo expander, design, processing and assembly requirements are proposed for the axial and radial dimensions. In the axial direction, if the internal depth of the expansion volute 1 is g, the outside thickness of the heat insulating member 314 is a, the bottom thickness is a1, the thickness of the bearing 313 is b, the thickness of the positioning ring 312 is c, the inside thickness of the cover plate 315 is d, the thickness of the expansion component 323 is e, and the thickness of the nozzle ring 322 is f. In the processing and assembly process, the size relationship is a+2b+c+d=g+x, x is the gap caused by processing or assembly, and the value range is 0-0.1 mm; e+f+a1+2b+c+d=g+y, y is also the gap caused by processing or assembly, y≤x, and the value range is -0.1-0 mm. At this time, the bottom of the heat insulating member 314 can be pressed against the bottom of the expansion volute 1 by the screw 12, and the expansion component 323 and the bottom of the expansion volute 1 have a gap of x-y, the maximum value of which is 0.2 mm. Under the gap (i.e. the first installation gap), the second seal 325 on the inside and outside can still realize sealing.

[0044] In an embodiment of the application, along the radial direction of the main shaft 311, the inside hole of the expansion component 323 is taken as the reference surface A, and the diameter is j. The inside hole coaxial tolerance of the heat insulating member 314 is h, and the outside circle coaxial tolerance is i. The inside hole of the main road outlet of the expansion volute 1 is taken as the reference surface B, and the diameter is j. The inside hole coaxial tolerance of the expansion volute 1 is k.

[0045] The coaxial tolerance relationship of the heat insulating member 314 and the expansion volute 1 is determined by the following formula:

[0046] h+i+k≤0.025j.

[0047] In the embodiment, under the above processing and assembly relationship, the assembly can be conveniently completed, and the influence on the low-temperature working medium expansion process caused by the tolerance can be accepted.

[0048] It should be noted that in this document, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0049] Finally, it should be noted that the above only describes the preferred embodiments of the present application, and is only used to illustrate the technical solutions of the present application, and is not intended to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A cryogenic turboexpander characterized by, The application relates to a turboexpander, which comprises an integrated expansion volute, a fan volute connected with the expansion volute, and a main machine arranged in the expansion volute, wherein an end plate of the expansion volute and the fan volute is fixed to an external cold box, so that the expansion volute and the main machine are completely arranged in the cold box; the main machine comprises a main unit and a subunit which is detachably connected with the main unit; the main unit is related to the shaft power level of a turboexpander; turboexpanders with the same shaft power level adopt the same main unit; the subunit is related to the design requirement of a turboexpander; for turboexpanders with different design requirements, only the expansion impeller, nozzle ring, expansion component and fan impeller included in the subunit need to be replaced according to different design parameters; the expansion component and the expansion volute have a first installation gap. The main unit comprises a main shaft, a positioning ring arranged outside the main shaft, two bearings fixedly connected with the positioning ring, an insulation member arranged outside one of the bearings, and a cover plate fixedly connected with the other bearing; the insulation member is located at the expansion side; the cover plate is fixedly connected with the end plate; the bearings and the expansion volute are provided with a first sealing member. In the axial direction of the main shaft, the first installation gap cannot exceed 0.2 mm, and is determined by the following formula: a-e-f-a1, wherein a is the thickness of the outer side of the insulation member, e is the thickness of the expansion component, f is the thickness of the nozzle ring, and a1 is the thickness of the bottom of the insulation member; In the radial direction of the main shaft, the inner hole of the expansion component is taken as a reference surface A, the diameter of which is j; the coaxial tolerance of the inner hole of the insulation member is h, and the coaxial tolerance of the outer circle of the insulation member is i; the inner hole of the main path outlet of the expansion volute is taken as a reference surface B, the diameter of which is j; the coaxial tolerance of the inner hole of the expansion volute is k; The coaxial tolerance relationship between the insulation member and the expansion volute is determined by the following formula: h+i+k<=0.025j.

2. The cryogenic turboexpander of claim 1, wherein, The design requirement includes the temperature, pressure and flow of the expansion working medium.

3. The cryogenic turboexpander of claim 1, wherein, The expansion impeller and the fan impeller are arranged on the main shaft, the nozzle ring and the expansion component are fixed on the insulation member, the nozzle ring and the expansion component form an expansion working medium flow channel, the expansion component and the expansion impeller have a second installation gap, and the expansion component is provided with a second sealing member on both sides.

4. The cryogenic turboexpander of claim 3, wherein, The fan volute and the end plate, the cover plate and the bearings, the cover plate and the end plate, the bearings and the positioning ring, and the expansion impeller, the nozzle ring and the insulation member are fixedly connected through screws.

5. The cryogenic turboexpander of claim 3, wherein, The insulation member and the main shaft, and the cover plate and the main shaft form a labyrinth seal.

6. The cryogenic turboexpander of claim 5, wherein, The expansion volute is provided with an inlet pipeline and an exhaust pipeline of process gas, and the process gas can enter the outer periphery of the bearing and the labyrinth seal.

7. The cryogenic turboexpander of claim 3, wherein, The expansion impeller and the fan impeller are fixed on the main shaft through nuts, and the fan volute is provided with mounting positions for mounting a rotating speed sensor and a displacement sensor, the rotating speed sensor is used for measuring the rotating speed of the main shaft, and the displacement sensor is used for measuring the displacement of the main shaft.

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