Novel oblique flow type natural gas underground compressor

Abstract

The invention relates to the field of pressurization and yield increase in natural gas extraction, in particular to a novel oblique flow type natural gas downhole compressor which comprises a multi-stage series structure and a plurality of connected single-stage compression modules, and each single-stage compression module comprises a diffusion pipeline and a rectification pipeline which are connected and coaxially arranged to form an axial advancing route of gas. Gas axially enters and is axially discharged; the air suction mechanism is arranged in the diffusion pipeline and used for sucking external air so that the external air can flow along the axial advancing route to do work and be pressurized; the same single-stage compression modules are connected in series in a multi-stage mode, the design difficulty is effectively reduced, meanwhile, the high pressure ratio can be achieved by adjusting the number of the compression modules, the high pressure ratio is achieved in the limited underground space, meanwhile, the compressor has the high reliability and the wide stable working margin, and the application range of the compressor is widened. And safe and reliable operation of the compressor under different working conditions is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of pressurization and production increase in natural gas exploitation, and in particular to a novel diagonal flow natural gas downhole compressor. Background Art

[0002] Natural gas is a clean and efficient energy source. It produces relatively low levels of pollutants and carbon dioxide during combustion, so it is considered a clean energy source. Natural gas has a wide range of sources and can exist naturally in strata, coexist with oil, or be dissolved in groundwater.

[0003] Natural gas extraction is a complex project involving a variety of technologies and methods. With the continuous development of natural gas boosting technology, downhole gas compression technology has become one of the main technologies for natural gas boosting. Since downhole compression requires the installation of a compressor in a limited pipe diameter space and a certain pressure increase ratio, it is difficult to design a compressor in a limited space. Summary of the invention

[0004] The purpose of the present invention is to provide a new type of inclined flow natural gas downhole compressor to solve the problems of downhole natural gas transportation, pressurization and production increase, so as to realize that the compression equipment can be installed within the limited diameter of the downhole pipe and achieve the required pressure increase ratio, ensure that each module has a smaller axial force, higher reliability and longer service life, and the compressor as a whole has a wide stable working margin while achieving a higher pressure increase ratio.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A novel diagonal flow natural gas downhole compressor is arranged in a multi-stage series structure, including a plurality of connected single-stage compression modules, wherein the single-stage compression modules include:

[0007] The expansion pipe and the rectification pipe are connected and coaxially arranged to form an axial path for the gas, so that the gas enters and is discharged axially;

[0008] The air intake mechanism is arranged in the pressure diffuser pipe and is used to attract external gas so that the external gas flows along the axial travel route to perform work and increase pressure.

[0009] As a further solution of the present invention: the air intake mechanism includes an oblique flow impeller arranged in the diffuser pipe, the oblique flow impeller is located at one end of the diffuser pipe away from the rectifier pipe, and the axial cross-section of the oblique flow impeller is arranged in an umbrella shape, on which a circumferential distribution component is provided, and the oblique flow impeller is also connected to a power component.

[0010] As a further solution of the present invention: the circumferential distribution structure includes a plurality of blade structures equidistantly distributed along the circumference, the blade structure includes adjacent long blades and short blades, and the length of the long blades is greater than the length of the short blades.

[0011] As a further solution of the present invention: the outlet inclination angle of the diagonal flow impeller is 60°-90°, and an ultra-low specific speed setting is adopted, and the specific speed is not less than 0.3.

[0012] As a further solution of the present invention: the power assembly includes a high-speed motor for driving the diagonal flow impeller to rotate, and the rotor of the height motor is supported by a front radial magnetic bearing and a rear radial magnetic bearing. Both the front radial magnetic bearing and the rear radial magnetic bearing use magnetic bearings, and a thrust bearing is also provided on the side of the rear radial magnetic bearing away from the front radial magnetic bearing.

[0013] As a further solution of the present invention: a plurality of bends are formed on the pressure diffuser pipe, the bends are arranged in an "S" shape, the plurality of bends are equidistantly distributed along the circumference of the pressure diffuser pipe and have a smooth transition, and the angle between the inlet of the pressure diffuser pipe and the tangent is 70°.

[0014] As a further solution of the present invention: a collecting structure is also provided on the rectifying pipe. The airflow passes through the rectifying and expanding pipe and enters the rectifying pipe. The collecting structure can collect the incoming airflow so that the flow direction of the airflow tends to be axial.

[0015] As a further solution of the present invention: the collecting structure includes a plurality of V-shaped openings formed on the rectifying pipe, the plurality of V-shaped openings are arranged equidistantly along the circumference and connected to the rectifying pipe exhaust port at one end of the rectifying pipe away from the diffuser pipe.

[0016] As a further solution of the present invention: the exhaust port of the rectification duct has an expansion angle, and the expansion angle is less than 10°.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) Compared with conventional compressors, the present application uses magnetic bearings and high-speed motors with a rotation speed exceeding 35,000 rpm, and adopts a multi-stage series compression layout. The radial dimension can be controlled at about 100 mm, so that the compression equipment can be installed in the well;

[0019] (2) The compression ratio of each single-stage compression module is about 1.1, and the volume flow rate does not change much. Therefore, each compression module is exactly the same. Through multi-stage series compression, the total compression ratio of the compressor can reach more than 1.5;

[0020] (3) The impeller adopts an ultra-low specific speed design, and the wheel is relatively slender, which realizes a small gas volume compression design. The long and short blade design improves the impeller pressure ratio and stable working range. The gas enters axially and is discharged at a certain angle to the axial direction, which improves the impeller's liquid carrying capacity;

[0021] (4) The multiple S-shaped channels of the diffuser can evenly divide the gas into multiple groups. The non-ventilated part in the middle can be wired. The air inlet angle of the diffuser is close to 70°. The S-shaped design effectively gradually brings the airflow from 70° to the axial direction. At the same time, the large S-shaped bend design effectively suppresses the flow separation in the diffuser. The radial dimension from the diffuser inlet to the outlet is also increasing, thus realizing the conversion from moving blade to static pressure.

[0022] The multiple V-shaped channels of the rectification pipe further rectify, gather and expand the gas passing through the expansion pipe, so that the gas approaches the axial direction with a certain degree of expansion, and the static pressure of the compressor is further increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a cross-sectional view of the overall structure of an embodiment of a new type of diagonal flow natural gas downhole compressor.

[0024] Figure 2 A cross-sectional view of a single-stage compression module in one embodiment of a new type of diagonal flow natural gas downhole compressor.

[0025] Figure 3 The figure is a front view of an inclined flow impeller in one embodiment of a novel inclined flow natural gas downhole compressor.

[0026] Figure 4 This is an axonometric view of a pressure expansion pipeline in one embodiment of a new type of diagonal flow natural gas downhole compressor.

[0027] Figure 5 The figure is a front view of a rectifying pipeline in one embodiment of a novel diagonal flow natural gas downhole compressor.

[0028] In the figure: 1, oblique flow impeller; 101, long blades; 102, short blades; 2, diffuser duct; 201, diffuser duct inlet; 202, bend; 3, rectifier duct; 301, V-shaped mouth; 302, rectifier duct exhaust port; 4, high-speed motor; 5, front radial magnetic bearing; 6, rear radial magnetic bearing; 7, thrust bearing. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In addition, when an element in the present invention is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0031] See also Figure 1-Figure 5 In an embodiment of the present invention, a novel diagonal flow natural gas downhole compressor is arranged in a multi-stage series structure, including a plurality of connected single-stage compression modules, wherein the single-stage compression modules include:

[0032] The expansion pipe 2 and the rectification pipe 3 are connected and coaxially arranged to form an axial path for the gas, so that the gas enters and is discharged axially;

[0033] The air intake mechanism is arranged in the diffuser pipe 2, and is used to attract external gas so that the external gas flows along the axial travel path to perform work and increase pressure.

[0034] In detail, the air intake mechanism includes an oblique flow impeller 1 arranged in the diffuser pipe 2, the oblique flow impeller 1 is located at one end of the diffuser pipe 2 away from the rectifier pipe 3, and the axial cross-section of the oblique flow impeller 1 is arranged in an umbrella shape, on which a circumferential distribution component is provided, and the oblique flow impeller 1 is also connected to a power component.

[0035] Furthermore, each of the single-stage compression modules is exactly the same. When working, the gas is sucked in axially through the diagonal flow impeller 1 to perform work and boost pressure, and then enters the expansion pipe 2 at a certain angle to the axial direction for further boosting and diversion, and finally enters the rectification pipe 3 to be collected to the axial direction and further expanded before entering the next stage for continued compression, thereby realizing axial gas entry and axial discharge, which not only ensures the stability of the airflow of the intake and exhaust at each level, but also takes away the liquid and particle components contained in the gas, further improving the output of the mine.

[0036] Please refer again Figure 3The circumferential distribution structure includes a plurality of blade structures equidistantly distributed along the circumference, and the blade structure includes adjacent long blades 101 and short blades 102 , wherein the length of the long blades 101 is greater than the length of the short blades 102 .

[0037] The diagonal flow impeller 1 adopts the shape of the long blades 101 and the short blades 102 to achieve a higher pressure ratio and a larger stable working range.

[0038] The outlet inclination angle of the diagonal flow impeller 1 is 60°-90°, and an ultra-low specific speed setting is adopted, and the specific speed is not less than 0.3.

[0039] In comparison, the impeller specific speed is between 0.3 and 0.4, which is much lower than the normal impeller specific speed of 0.8, and can be used for compressing more than 4,000 standard cubic meters of natural gas per day.

[0040] The power assembly includes a high-speed motor 4 for driving the diagonal flow impeller 1 to rotate. The rotor of the height motor 4 is supported by a front radial magnetic bearing 5 and a rear radial magnetic bearing 6. Both the front radial magnetic bearing 5 and the rear radial magnetic bearing 6 use magnetic bearings. A thrust bearing 7 is also provided on the side of the rear radial magnetic bearing 6 facing away from the front radial magnetic bearing 5.

[0041] Among them, the front radial magnetic bearing 5 and the rear radial magnetic bearing 6 both adopt magnetic bearings, which can realize oil-free lubrication and support. The thrust bearing 7 is used to balance the axial force generated by the impeller aerodynamics. The outlet inclination angle of the inclined flow impeller 1 is 60°-90°, so as to rectify the airflow, that is, the airflow can be better adjusted to the axial direction. The compressor has axial air intake and axial exhaust, which improves the compressor's ability to carry liquids and particles, further improves the mine's production capacity, and at the same time ensures that it has the maximum radial size to accommodate the high-speed motor 4.

[0042] It should also be added that, in the present application, multiple identical single-stage compression modules are used for multi-stage series compression, the rotation speed of the high-speed motor 4 is higher than 35,000 rpm, and the compression ratio of each stage is greater than 1.1, and the multi-stage series compression boost ratio is greater than 1.5.

[0043] Magnetic bearings are a new type of high-performance bearings, whose main feature is to use magnetic field force to suspend the rotor in the air, thereby realizing a support method without mechanical contact. Compared with traditional ball bearings, sliding bearings and oil film bearings, magnetic bearings do not have mechanical contact, so they have the advantages of less mechanical wear, high operating speed, low energy consumption, low noise and long life. Therefore, the application of magnetic bearings in this application can effectively improve the working performance of the compressor.

[0044] Please refer again Figure 4The pressure diffuser pipe 2 is provided with a plurality of curved portions 202, the curved portions 202 are arranged in an "S" shape, the plurality of curved portions 202 are evenly distributed along the circumference of the pressure diffuser pipe 2 and have a smooth transition, and the pressure diffuser pipe inlet 201 and the tangential angle (i.e., the attached Figure 4 The Ψ) shown in FIG is 70°.

[0045] In the embodiment of the present invention, the setting of the diffuser pipe inlet 201 with a tangential angle of 70° is mainly to adapt to the outlet airflow direction of the impeller;

[0046] Secondly, preferably, the number of the curved portions 202 is 8, and the 70° airflow direction is gradually twisted to the axial direction through the design of 8 evenly distributed and smoothly transitioned curved portions 202, so that the airflow can smoothly transition and minimize the flow loss. At the same time, the radial dimension of the pressure diffuser duct 2 is increased to a certain extent, thereby achieving an increase in static pressure rise while achieving an airflow twisting angle.

[0047] Furthermore, the eight S-shaped channels evenly divide the gas into eight groups, and the middle part without air can be wired. The air inlet angle of the diffuser pipe 2 is close to 70°. The S-shaped design effectively gradually approaches the airflow from 70° to the axial direction. At the same time, the large S-shaped bend design effectively suppresses the flow separation in the diffuser. The radial dimension from the diffuser inlet to the outlet is also increasing, so the conversion from the moving blade to the static pressure is also achieved.

[0048] Please refer again Figure 5 The rectifying pipe 3 is also provided with a collecting structure. The airflow passes through the rectifying and expanding pipe 2 and enters the rectifying pipe 3. The collecting structure can collect the incoming airflow so that the flow direction of the airflow tends to be axial.

[0049] The collecting structure includes a plurality of V-shaped openings 301 formed on the rectifying pipe 3 , wherein the plurality of V-shaped openings 301 are arranged equidistantly along the circumference and connected to a rectifying pipe exhaust port 302 at one end of the rectifying pipe 3 away from the diffuser pipe 2 .

[0050] Preferably, the number of the V-shaped openings 301 is four.

[0051] The rectifier duct exhaust port 302 has an expansion angle, and the expansion angle (i.e. Figure 2 The θ shown in FIG) is less than 10°.

[0052] Furthermore, after the airflow is rectified and diffused by the diffuser pipe 2, the airflow immediately enters the rectifier pipe 3, and the airflow is gathered together through the four V-shaped ports 301. At this time, the airflow is basically close to the axial direction, so as to achieve the effect of axial intake and axial exhaust.

[0053] In addition, controlling the expansion angle of the rectifier duct exhaust port 302 within 10° not only ensures that the airflow will not separate, but also further improves the static pressure rise.

[0054] In summary, the present invention can be used as a natural gas underground compression structure, achieving a higher pressure increase ratio in a relatively limited space underground, and the compressor has higher reliability and a wide stable working margin, ensuring that the compressor can operate safely and reliably under different working conditions;

[0055] Specifically, the use of an ultra-low specific speed diagonal flow impeller 1 makes the compressor suitable for compression, boosting and production increase of gas wells with smaller flow rates. The characteristics of axial entry and axial discharge improve the liquid carrying capacity of the compressor. The S-type expansion and V-type rectification channel design realizes effective expansion and gas rectification of the compressor. By connecting the same single-stage compression module in series in multiple stages, the design difficulty is effectively reduced. At the same time, a higher compression ratio can be achieved by adjusting the number of compression modules. The total compression ratio can reach more than 1.5. At the same time, due to the low pneumatic load borne by each compression module, the compressor as a whole is also guaranteed to have a higher stable working range.

[0056] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0057] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A new type of diagonal flow natural gas downhole compressor, which is arranged in a multi-stage series structure, including multiple connected single-stage compression modules; It is characterized in that The single-stage compression module comprises: The pressure diffuser pipe (2) and the rectifying pipe (3) are connected and coaxially arranged to form an axial path for the gas, so that the gas enters axially and is discharged axially; The air intake mechanism is arranged in the pressure diffuser pipe (2) and is used to absorb external gas so that the external gas flows along the axial travel route to perform work and increase pressure.

2. A novel diagonal flow natural gas downhole compressor according to claim 1, characterized in that: The air intake mechanism comprises an oblique flow impeller (1) arranged in the diffuser pipe (2), the oblique flow impeller (1) being located at one end of the diffuser pipe (2) away from the rectifying pipe (3), and the axial cross section of the oblique flow impeller (1) being arranged in an umbrella-like shape, on which a circumferential distribution component is arranged, and the oblique flow impeller (1) is also connected to a power component.

3. A novel diagonal flow natural gas downhole compressor according to claim 2, characterized in that: The circumferential distribution structure comprises a plurality of groups of blade structures equidistantly distributed along the circumference, the blade structure comprising adjacent long blades (101) and short blades (102), the length of the long blades (101) being greater than the length of the short blades (102).

4. A novel diagonal flow natural gas downhole compressor according to claim 3, characterized in that: The outlet inclination angle of the diagonal flow impeller (1) is 60°-90°, and an ultra-low specific speed setting is adopted, with the specific speed not less than 0.

3.

5. A novel diagonal flow natural gas downhole compressor according to claim 4, characterized in that: The power assembly comprises a high-speed motor (4) for driving the diagonal flow impeller (1) to rotate, the rotor of the high-speed motor (4) is supported by a front radial magnetic bearing (5) and a rear radial magnetic bearing (6), both the front radial magnetic bearing (5) and the rear radial magnetic bearing (6) are magnetic bearings, and a thrust bearing (7) is further provided on a side of the rear radial magnetic bearing (6) away from the front radial magnetic bearing (5).

6. A novel diagonal flow natural gas downhole compressor according to claim 1, characterized in that: A plurality of curved portions (202) are formed on the pressure diffuser pipe (2), the curved portions (202) are arranged in an "S" shape, the plurality of curved portions (202) are equidistantly distributed along the circumference of the pressure diffuser pipe (2) and have a smooth transition, and the angle between the pressure diffuser pipe inlet (201) and the tangent is 70°.

7. The novel diagonal flow natural gas downhole compressor according to claim 1 is characterized in that: The rectifying pipe (3) is also provided with a collecting structure. The airflow passes through the rectifying and expanding pipe (2) and enters the rectifying pipe (3). The collecting structure can collect the incoming airflow so that the flow direction of the airflow tends to be axial.

8. The novel diagonal flow natural gas downhole compressor according to claim 7 is characterized in that: The collecting structure comprises a plurality of V-shaped openings (301) formed on the rectifying pipe (3), wherein the plurality of V-shaped openings (301) are arranged at equal intervals along a circumference and connected to a rectifying pipe exhaust port (302) at one end of the rectifying pipe (3) away from the diffuser pipe (2).

9. A novel diagonal flow natural gas downhole compressor according to claim 8, characterized in that: The rectification duct exhaust port (302) has an expansion angle, and the expansion angle is less than 10°.

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