Multi-shaft centrifugal compressor and liquefied natural gas device

Abstract

The utility model provides a multi-shaft centrifugal compressor and a liquefied natural gas device. The multi-shaft centrifugal compressor comprises a gear box, and the gear box comprises a first-second-stage rotor and a third-fourth-stage rotor; the first-stage stator and the second-stage stator are arranged at the two ends of the first-stage and second-stage rotor and detachably connected to the gear box, the first-stage stator is arranged at one end of the first-stage and second-stage rotor in a sleeving mode through a first-stage dry gas sealing sleeve, and the second-stage stator is arranged at the other end of the first-stage and second-stage rotor in a sleeving mode through a second-stage dry gas sealing sleeve; the third-stage stator and the fourth-stage stator are arranged at the two ends of the third-fourth-stage rotor and detachably connected to the gear box, the third-stage stator is arranged at one end of the third-fourth-stage rotor in a sleeving mode through a third-stage dry gas sealing sleeve, and the fourth-stage stator is arranged at the other end of the third-fourth-stage rotor in a sleeving mode through a fourth-stage dry gas sealing sleeve. Through arrangement of the first-stage dry gas seal, the second-stage dry gas seal, the third-stage dry gas seal and the fourth-stage dry gas seal, leakage of process gas is effectively avoided, zero leakage of flammable and explosive gas conveyed by the multi-shaft centrifugal compressor is achieved, and application of the multi-shaft centrifugal compressor to a liquefied natural gas device is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of compressors, and particularly relates to a multi-shaft centrifugal compressor and a liquefied natural gas device. BACKGROUND

[0002] Liquefied natural gas (LNG for short) is the most safe, suitable for long-distance transportation and directly usable clean energy in the world at present. In the liquefaction process of the liquefied natural gas, a mixed refrigerant compressor is one of core equipment.

[0003] Previously, a large-scale liquefied natural gas compressor usually adopts a single-shaft centrifugal compressor, and its working mode is to drive multiple impellers through a single shaft to perform compression. Compared with a multi-shaft centrifugal compressor, the single-shaft centrifugal compressor has low efficiency, high cost and complex installation.

[0004] At present, a related multi-shaft centrifugal compressor is mainly applied to non-flammable and non-explosive gases such as air, nitrogen and carbon dioxide. The shaft end sealing of the multi-shaft centrifugal compressor adopts a labyrinth sealing or a carbon ring sealing. This sealing mode allows the leakage of the transported gas. However, the liquefied natural gas refrigerant compression belongs to an energy chemical industry, and is flammable and explosive medium. Therefore, the sealing property is extremely high, and the leakage of the transported gas is not allowed. This results in that the existing multi-shaft centrifugal compressor cannot be applied to the liquefied natural gas device. Therefore, a multi-shaft centrifugal compressor and a liquefied natural gas device are provided. CONTENT OF THE INVENTION

[0005] Therefore, the application aims to provide a multi-shaft centrifugal compressor and a liquefied natural gas device, which can solve at least one technical problem in the prior art.

[0006] In order to solve the above problems, the first aspect of the application provides a multi-shaft centrifugal compressor, which comprises:

[0007] a gear box, the gear box comprising a first-second-stage rotor and a third-fourth-stage rotor;

[0008] a first-stage stator and a second-stage stator, the first-stage stator and the second-stage stator being arranged at both ends of the first-second-stage rotor and being detachably connected to the gear box, the first-stage stator being sleeved at one end of the first-second-stage rotor through a first-stage dry gas seal, and the second-stage stator being sleeved at the other end of the first-second-stage rotor through a second-stage dry gas seal;

[0009] a third-stage stator and a fourth-stage stator, the third-stage stator and the fourth-stage stator being arranged at both ends of the third-fourth-stage rotor and being detachably connected to the gear box, the third-stage stator being sleeved at one end of the third-fourth-stage rotor through a third-stage dry gas seal, and the fourth-stage stator being sleeved at the other end of the third-fourth-stage rotor through a fourth-stage dry gas seal.

[0010] Optionally, the first-stage stator, the second-stage stator, the third-stage stator and the fourth-stage stator comprise a volute, and the volute is manufactured by a whole casting process.

[0011] Optionally, the first-stage stator, the second-stage stator, the third-stage stator and the fourth-stage stator further comprise a ring, and the ring is arranged in the volute to form a tapered flow channel between the ring and the volute.

[0012] Optionally, the compressor further comprises a first-stage inlet guide vane and a second-stage inlet guide vane, the first-stage inlet guide vane is arranged at an inlet end of the first-stage stator, and the second-stage inlet guide vane is arranged at an inlet end of the third-stage stator.

[0013] Optionally, the first-stage rotor and the second-stage rotor are respectively provided with an impeller at two ends thereof, and the third-stage rotor and the fourth-stage rotor are respectively provided with an impeller at two ends thereof, and the impellers are arranged in a back-to-back manner.

[0014] Optionally, the impeller is a three-dimensional impeller.

[0015] Optionally, the gear box further comprises a driving shaft, the driving shaft comprises a first end, and the first end of the driving shaft is connected with the shaft head pump to drive the shaft head pump to work to supply oil to a lubricating system of the compressor.

[0016] Optionally, the gear box further comprises a driving part, the driving shaft further comprises a second end, and the driving part is connected with the second end of the driving shaft to drive the driving shaft to rotate.

[0017] Optionally, the gear box further comprises a box body, the first-stage rotor, the second-stage rotor, the third-stage rotor, the fourth-stage rotor and the driving shaft are arranged in the box body, the first-stage rotor and the second-stage rotor are arranged on one side of the driving shaft, the third-stage rotor and the fourth-stage rotor are arranged on the other side of the driving shaft, a large gear is arranged on the driving shaft, and the large gear is engaged with the first-stage rotor, the second-stage rotor, the third-stage rotor and the fourth-stage rotor.

[0018] The second aspect of the application provides a liquefied natural gas device comprising the multi-shaft centrifugal compressor.

[0019] By means of the above technical solution, the application has at least the following beneficial effects:

[0020] 1. The embodiment of the present application provides a kind of multi-shaft centrifugal compressor, by installing primary dry gas seal between one two-stage rotor and primary stator, by installing secondary dry gas seal between one two-stage rotor and secondary stator, by installing tertiary dry gas seal between three four-stage rotor and tertiary stator, by installing quaternary dry gas seal between three four-stage rotor and quaternary stator, with high pressure process gas as sealing gas, introduced from compressor outlet, buffer gas uses low pressure nitrogen, effectively avoid the leakage of process gas, realize the zero leakage of multi-shaft centrifugal compressor conveying flammable and explosive gas, realize the application of multi-shaft centrifugal compressor in liquefied natural gas device.

[0021] 2, The embodiment of the present application provides a kind of hydraulic natural gas device, using the multi-shaft centrifugal compressor with zero leakage, compared with the hydraulic natural gas device using single-shaft centrifugal compressor, with the advantages of high working efficiency, low cost and convenient field installation. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the structure schematic diagram of the multi-shaft centrifugal compressor of the embodiment of the present application.

[0023] The reference signs are shown as follows:

[0024] 1, primary stator;2, secondary stator;3, tertiary stator;4, quaternary stator;5, one two-stage rotor;6, three four-stage rotor;7, large gear;8, gear box;9, one section inlet guide vane;10, two section inlet guide vane;11, shaft head pump;12, primary dry gas seal;13, secondary dry gas seal;14, tertiary dry gas seal;15, quaternary dry gas seal. DETAILED DESCRIPTION

[0025] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0026] In addition, the terms "first", "second" are only for description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0027] In this application, unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0028] The preferred embodiments of the utility model are described below in combination with the drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the utility model, and are not used to limit the utility model.

[0029] In combination with the drawings Figure 1 As shown in the drawings, according to the first aspect of the embodiment of the application, a multi-shaft centrifugal compressor is provided, comprising a gear box 8, a first-stage stator 1, a second-stage stator 2, a third-stage stator 3 and a fourth-stage stator 4;

[0030] The gear box 8 comprises a first-stage and second-stage rotor 5 and a third-stage and fourth-stage rotor 6; the first-stage stator 1 and the second-stage stator 2 are arranged at both ends of the first-stage and second-stage rotor 5 and are detachably connected to the gear box 8; the first-stage stator 1 is sleeved at one end of the first-stage and second-stage rotor 5 through a first-stage dry gas seal 12, and the second-stage stator 2 is sleeved at the other end of the first-stage and second-stage rotor 5 through a second-stage dry gas seal 13; the third-stage stator 3 and the fourth-stage stator 4 are arranged at both ends of the third-stage and fourth-stage rotor 6 and are detachably connected to the gear box 8; the third-stage stator 3 is sleeved at one end of the third-stage and fourth-stage rotor 6 through a third-stage dry gas seal 14, and the fourth-stage stator 4 is sleeved at the other end of the third-stage and fourth-stage rotor 6 through a fourth-stage dry gas seal 15.

[0031] By installing the first-stage dry gas seal 12 between one end of the first-stage and second-stage rotor 5 and the first-stage stator 1, installing the second-stage dry gas seal 13 between the other end of the first-stage and second-stage rotor 5 and the second-stage stator 2, installing the third-stage dry gas seal 13 between one end of the third-stage and fourth-stage rotor 6 and the third-stage stator 3, and installing the fourth-stage dry gas seal 15 between the other end of the third-stage and fourth-stage rotor 6 and the fourth-stage stator 4, high-pressure process gas is used as sealing gas, which is introduced from the compressor outlet, and low-pressure nitrogen gas is used as buffer gas, which effectively avoids the leakage of process gas, realizes zero leakage of the multi-shaft centrifugal compressor for conveying flammable and explosive gas, and realizes the application of the multi-shaft centrifugal compressor in a liquefied natural gas device.

[0032] The first-stage dry gas seal 12, the second-stage dry gas seal 13, the third-stage dry gas seal 14, and the fourth-stage dry gas seal 15 each include a dynamic ring and a static ring, that is, the first-stage dry gas seal 12 and the second-stage dry gas seal 13 are respectively installed at the two ends of the first-stage and second-stage rotor 5 through the dynamic rings thereof, and the third-stage dry gas seal 14 and the fourth-stage dry gas seal 15 are respectively installed at the two ends of the third-stage and fourth-stage rotor 6 through the dynamic rings thereof; the first-stage stator 1 is sleeved on the static ring of the first-stage dry gas seal 12, the second-stage stator 2 is sleeved on the static ring of the second-stage dry gas seal 13, the third-stage stator 3 is sleeved on the static ring of the third-stage dry gas seal 14, and the fourth-stage stator 4 is sleeved on the static ring of the fourth-stage dry gas seal; the arrangement of the dry gas seals achieves zero leakage and does not interfere with the rotation of the first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6.

[0033] In the present application, the multi-shaft compressor is a two-stage two-shaft four-stage structure; the compression process is divided into two stages, and each stage compresses gas through two-stage impellers.

[0034] In some embodiments, the first-stage stator 1, the second-stage stator 2, the third-stage stator 3, and the fourth-stage stator 4 include a volute, which is made by integral casting.

[0035] The integral casting process has the following technical effects: integral casting can ensure the structural integrity of the volute, avoiding structural defects and sealing problems that may be caused by split assembly. As a key component of the compressor, the structural integrity of the volute is crucial to the performance and efficiency of the compressor. The integral cast volute can better meet the requirements of flow passage shape, dimensional accuracy, etc., thereby improving the gas flow efficiency and compression efficiency of the compressor. The integral cast volute is more uniform in material distribution and structure, and can better withstand high-pressure, high-speed, and high-temperature gas flow impact, enhancing the strength and durability of the volute.

[0036] Compared with split assembly, integral casting simplifies the production process, reduces assembly procedures and related quality control links. This not only improves production efficiency, but also reduces production cost.

[0037] In some embodiments, the first-stage stator 1, the second-stage stator 2, the third-stage stator 3, and the fourth-stage stator 4 further include a profile ring, which is arranged in the volute to form a converging-diverging flow passage between the profile ring and the volute. The converging-diverging flow passage helps to reduce the kinetic energy loss of the fluid and make the fluid flow more stably; at the same time, it also reduces the vibration and noise caused by excessive flow velocity.

[0038] The converging-diverging flow passage is provided with a blade diffuser. Through the arrangement of the blade diffuser, the fluid flowing through the converging-diverging flow passage of the volute is better, the flow loss is reduced, and the efficiency of the compressor is improved.

[0039] In some embodiments, the compressor further comprises a first-stage inlet guide vane 9 and a second-stage inlet guide vane 10, the first-stage inlet guide vane 9 is arranged at the inlet end of the first-stage stator 1, and the second-stage inlet guide vane 10 is arranged at the inlet end of the third-stage stator 3.

[0040] Through the arrangement of the first-stage inlet guide vane 9 and the second-stage inlet guide vane 10, the inlet flow and pressure of the compressor are controlled, precise process control and efficient operation are realized. Compared with the frequency conversion control design of similar applications, the investment cost is significantly reduced.

[0041] In some embodiments, impellers are arranged at both ends of the first-stage and second-stage rotor 5 and at both ends of the third-stage and fourth-stage rotor 6, and the impellers are arranged in a back-to-back manner.

[0042] The four impellers are driven by the first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6 to compress gas, ensuring that each stage operates stably at the optimal speed.

[0043] The impellers are arranged in a back-to-back manner, that is, the two impellers arranged at both ends of the first-stage and second-stage rotor 5 are arranged in a back-to-back manner, and the two impellers arranged at both ends of the third-stage and fourth-stage rotor 6 are also arranged in a back-to-back manner. That is, the two impellers arranged on the same rotor are arranged in a back-to-back manner. This can effectively balance the aerodynamic thrust generated during compression, greatly improving the safety and reliability of the unit operation.

[0044] In some embodiments, the impeller is a three-dimensional impeller. The installation of the three-dimensional impeller makes the inlet flow passage wider and the outlet flow passage narrower, so that the fluid obtains free expansion and compression in the inlet and outlet, thereby reducing the fluctuation loss of the fluid and significantly improving the compression efficiency of the compressor.

[0045] In some embodiments, the gear box 8 further comprises a drive shaft, the drive shaft comprises a first end, and the first end of the drive shaft is connected with the shaft head pump 11, for driving the shaft head pump 11 to work to supply oil to the lubrication system of the compressor.

[0046] The shaft head pump 11 is connected with the first end of the drive shaft, that is, the input end of the shaft head pump 11 is connected with the first end of the drive shaft through a shaft coupling, and the shaft head pump 11 is driven to rotate synchronously by the rotation of the drive shaft to supply oil to the lubrication system of the compressor. The shaft head pump 11 is used to supply oil to the lubrication system of the compressor, replacing the traditional high oil tank and the traditional double electric pump and high oil tank oil supply mode, which has the problems of limited installation position and large occupied space. The shaft head pump 11 of the present application uses the drive shaft as the power source, without the need for an additional power source. This not only simplifies the oil supply system, but also facilitates on-site installation and reduces costs.

[0047] In some embodiments, the gear box 8 further comprises a driving part, the driving shaft further comprises a second end, and the driving part is connected to the second end of the driving shaft for driving the driving shaft to rotate.

[0048] The driving part is connected to the second end of the driving shaft, that is, the driving part is connected to the driving shaft through a shaft coupling for the convenience of installation, and the driving part provides driving force to drive the driving shaft to rotate.

[0049] The first end and the second end of the driving shaft, that is, the opposite ends of the driving shaft, that is, the shaft head pump 11 and the driving part are arranged on different ends of the driving shaft to realize driving of the entire system by the same power source.

[0050] In some embodiments, the gear box 8 further comprises a box body, the first-stage and second-stage rotor 5, the third-stage and fourth-stage rotor 6, and the driving shaft are arranged in the box body, the first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6 are arranged on two sides of the driving shaft, the driving shaft is provided with a bull gear 7, and the bull gear 7 is engaged with the first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6.

[0051] The box body serves as a carrier of the driving shaft, the first-stage and second-stage rotor 5, the third-stage and fourth-stage rotor 6, and the like, and has sufficient rigidity to avoid deformation after the compressor operates.

[0052] The first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6 are gear shafts, the gear teeth on the gear shafts are engaged with the bull gear arranged on the driving shaft, and the bull gear drives the first-stage and second-stage rotor 5 and the third-stage and fourth-stage rotor 6 to rotate synchronously.

[0053] More specific implementation process is as follows:

[0054] The rotation of the impeller in the first-stage stator 1 converts the energy driven by the driving machine into pressure energy of the gas, and the pressure energy is increased by the pressure booster to compress the mixed refrigerant in the first stage. The mixed refrigerant enters the second-stage stator 2 through the inter-stage gas pipeline of the first-stage and second-stage to be further compressed, and then enters the inter-stage cooler to be cooled. The mixed refrigerant gas (a mixture composed of methane, ethylene, propane, isopentane, nitrogen and the like) is compressed to the expected pressure by the compressor, enters the user process to be throttled and expanded to refrigerate, absorbs the heat released in the liquefaction process of natural gas, and meets the cold quantity required for the production of liquefied natural gas through the closed compression / expansion cycle operation.

[0055] The second aspect of the application provides a liquefied natural gas device comprising the multi-shaft centrifugal compressor of any one of the above.

[0056] The multi-shaft centrifugal compressor with zero leakage is adopted in the liquefied natural gas device, compared with the hydraulic natural gas device adopting single-shaft centrifugal compressor, has the advantages of high working efficiency, low cost and convenient field installation.

[0057] The multi-shaft centrifugal compressor provided by the application is highly suitable for the liquefied natural gas device, compared with the single-shaft centrifugal compressor, first, the investment of frequency converter can be saved, second, the multi-shaft centrifugal compressor technology can effectively reduce energy consumption, about 4% to 7% can be saved. In addition, the multi-shaft centrifugal compressor adopts integrated design of compressor and gear box and shaft head pump oil supply, so that the structure is more compact, not only reduces the equipment floor area, but also facilitates installation and maintenance.

[0058] It is easy for those skilled in the art to understand that the above advantageous modes can be freely combined and superimposed without conflict.

[0059] The above is only the preferred embodiment of the application, and is not used to limit the application, any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application. The above is only the preferred embodiment of the application, it should be pointed out that, for ordinary skilled in the art, without departing from the technical principles of the application, a number of improvements and modifications can be made, these improvements and modifications should be regarded as the protection scope of the application.

Claims

1. A multi-shaft centrifugal compressor, characterized by, The compressor comprises: a gear box (8) comprising a first and second stage rotor (5) and a third and fourth stage rotor (6); a first stage stator (1) and a second stage stator (2) arranged at both ends of the first and second stage rotor (5) and detachably connected to the gear box (8), the first stage stator (1) being sleeved on one end of the first and second stage rotor (5) through a first stage dry gas seal (12), and the second stage stator (2) being sleeved on the other end of the first and second stage rotor (5) through a second stage dry gas seal (13); a third stage stator (3) and a fourth stage stator (4) arranged at both ends of the third and fourth stage rotor (6) and detachably connected to the gear box (8), the third stage stator (3) being sleeved on one end of the third and fourth stage rotor (6) through a third stage dry gas seal (14), and the fourth stage stator (4) being sleeved on the other end of the third and fourth stage rotor (6) through a fourth stage dry gas seal (15).

2. A multishaft centrifugal compressor according to claim 1, characterized in that The first stage stator (1), the second stage stator (2), the third stage stator (3) and the fourth stage stator (4) comprise volutes which are made by integral casting process.

3. A multishaft centrifugal compressor according to claim 2, characterized in that The first stage stator (1), the second stage stator (2), the third stage stator (3) and the fourth stage stator (4) further comprise rings which are arranged in the volutes to form tapered flow channels between the rings and the volutes.

4. A multi-shaft centrifugal compressor according to claim 1, characterized in that The compressor further comprises a first stage inlet guide vane (9) and a second stage inlet guide vane (10), the first stage inlet guide vane (9) being arranged at an inlet end of the first stage stator (1), and the second stage inlet guide vane (10) being arranged at an inlet end of the third stage stator (3).

5. A multistage centrifugal compressor according to claim 1, wherein Impellers are arranged at both ends of the first and second stage rotor (5) and the third and fourth stage rotor (6) respectively, and the impellers are arranged in back-to-back manner.

6. A multistage centrifugal compressor according to claim 5, wherein The impellers are three-dimensional impellers.

7. A multistage centrifugal compressor according to claim 1, wherein The gear box (8) further comprises a driving shaft, the driving shaft comprising a first end, the first end of the driving shaft being connected with a shaft head pump (11) for driving the shaft head pump (11) to work to supply oil to a lubricating system of the compressor.

8. A multistage centrifugal compressor according to claim 7, characterized in that The gear box (8) further comprises a driving part, the driving shaft further comprising a second end, the driving part being connected with the second end of the driving shaft for driving the driving shaft to rotate.

9. A multistage centrifugal compressor according to claim 7, wherein The gear box (8) further comprises a box body, the first and second stage rotor (5), the third and fourth stage rotor (6) and the driving shaft being arranged in the box body, the first and second stage rotor (5) being arranged on both sides of the driving shaft, a large gear (7) being arranged on the driving shaft and engaging with the first and second stage rotor (5) and the third and fourth stage rotor (6) simultaneously.

10. A liquefied natural gas plant characterized by, The multi-shaft centrifugal compressor comprises any one of claims 1 to 9.

Images