A full-bore high-pressure ceramic elbow for oil and gas wellheads

Abstract

The present invention discloses a full-bore high-pressure ceramic elbow for oil and gas wellheads, which relates to the technical field of ceramic elbows and includes a metal elbow and a ceramic inner lining pipe. Two metal flanges with RJ ring connection surfaces are respectively fixed at both ends of the metal elbow. An inner cavity is arranged inside the metal elbow, and the ceramic inner lining pipe is arranged in the inner cavity. One end of the ceramic inner lining pipe is connected with a buffer pipe, and the buffer pipe includes a metal pipe and a ceramic convex section. The metal pipe is fixedly arranged inside the inner cavity, and the ceramic convex section is fixedly sleeved inside the metal pipe. A flat section, an inclined section and an arc convexity are sequentially arranged on the inner side wall of the ceramic convex section. In the present invention, the setting of the buffer pipe can pre-buffer the flowing medium before it enters the ceramic inner lining pipe, relieve the impact pressure on the ceramic inner lining pipe when the flowing medium changes its flow direction, thereby greatly reducing the impact abrasion suffered by the ceramic inner lining pipe and improving the service life of the ceramic elbow.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic elbows, and particularly relates to a full-bore high-pressure ceramic elbow for oil and gas wellheads. Background Art

[0002] Currently, there are multiple elbows arranged on the oil production tree device at the oil wellhead and the gas production tree device at the natural gas wellhead. Since the media in oil wells and natural gas wells contain a large amount of formation sand and have a very high pressure, and the media flow rate is very fast, the wear on the elbows is very strong. In severe cases, the elbow will be punctured and leaked outside within one week, and it is necessary to frequently stop production to replace or repair weld the elbows, which greatly affects the production efficiency and poses a great safety hazard.

[0003] In order to ensure the service life of the pipeline and prevent the outer side of the elbow from being worn through due to the inertial force when the flowing medium passes through the turning point of the elbow, ceramic chips are often fixed inside the elbow to increase the wear resistance of the inner wall of the elbow. However, for the current reducing elbows, the connection between the internal ceramic chips is not tight enough and the gap is relatively large. After long-term use, the ceramic chips are prone to fall off under the impact of the flowing medium, thus affecting the service life of the elbow. Moreover, the lengths of both ends of the elbow are usually relatively short, and part of the impact force of the flowing medium will also act on the connection part between the elbow and other pipelines. Over time, the connection part is prone to looseness, resulting in leakage of the flowing medium.

[0004] In view of the above problems, a full-bore high-pressure ceramic elbow for oil and gas wellheads is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a full-bore high-pressure ceramic elbow for oil and gas wellheads to solve the above problems.

[0006] To solve the above technical problems, the present invention specifically provides the following technical solutions:

[0007] A full-bore high-pressure ceramic elbow for oil and gas wellheads includes a metal elbow and a ceramic inner liner. Two metal flanges with RJ ring connection surfaces are respectively fixed at both ends of the metal elbow. An inner cavity is provided inside the metal elbow, and the ceramic inner liner is arranged inside the inner cavity. One end of the ceramic inner liner is connected with a buffer pipe. The buffer pipe includes a metal pipe and a ceramic protruding section. The metal pipe is fixedly arranged inside the inner cavity, and the ceramic protruding section is fixedly sleeved inside the metal pipe. A flat section, an inclined section, and an arc-shaped protrusion are sequentially arranged on the inner side wall of the ceramic protruding section. Flange connectors are arranged on both of the two metal flanges.

[0008] As a preferred embodiment of the present invention, the ceramic inner lining tube comprises a plurality of angled ceramic elbow segments, and all the ceramic elbow segments are sequentially arranged inside the inner cavity. At both ends inside the inner cavity, a first straight tube segment and a second straight tube segment are respectively arranged. The first straight tube segment is located between the ceramic inner lining tube and the buffer tube, and one end of the second straight tube segment abuts against the adjacent ceramic elbow segment.

[0009] As a preferred embodiment of the present invention, the gentle section is connected to the first straight tube segment, and the arc-shaped protrusion is connected to the ceramic elbow segment.

[0010] As a preferred embodiment of the present invention, a ceramic connecting tube is arranged inside the metal tube, and the inner diameter of the ceramic connecting tube is the same as that of the first straight tube segment. There are a plurality of ceramic protrusion segments, and the plurality of ceramic protrusion segments are uniformly arranged inside the ceramic connecting tube along the circumferential direction.

[0011] As a preferred embodiment of the present invention, the flange connecting member comprises a fastening collar, a threaded collar, and a threaded connecting ring. The fastening collar is fixedly sleeved outside the metal flange. The threaded collar is threadedly connected to the outer wall of the metal flange of another ceramic elbow. The threaded connecting ring is fixed at one end of the outer wall of the threaded collar close to the fastening collar, and the inner diameter of the threaded connecting ring is the same as that of the threaded collar. The threaded connecting ring is threadedly connected to the fastening collar. A sealing gasket is arranged at the edge of the inner bottom wall of the fastening collar, and the sealing gasket is adapted to the threaded connecting ring.

[0012] As a preferred embodiment of the present invention, a plurality of through holes are penetrated through all the metal flanges, and all the through holes are uniformly arranged on the inner wall of the metal flange along the circumferential direction. All the through holes on one of the metal flanges are inserted with fastening screws, and one ends of all the fastening screws are fixedly connected to one of the metal flanges. The other ends of all the fastening screws are threadedly connected with nuts.

[0013] As a preferred embodiment of the present invention, mounting grooves are formed at the outer extensions of all the metal flanges, sealing rings are arranged on all the mounting grooves, and a plurality of perforations for bolts to pass through are formed in the sealing rings along the circumferential direction.

[0014] As a preferred embodiment of the present invention, the ceramic inner lining tube is cut into a plurality of ceramic elbow segments with an angle of α°, and the range of the angle α° is 2° to 20°.

[0015] As a preferred embodiment of the present invention, the length of the second straight tube segment is greater than that of the first straight tube segment.

[0016] As a preferred embodiment of the present invention, protrusions are provided at both ends of the ceramic convex section, and grooves for accommodating the protrusions are formed at one end of the ceramic inner lining pipe and one end of the first straight pipe section.

[0017] The present invention has the following beneficial effects compared with the prior art:

[0018] 1. By providing multiple ceramic elbow sections, the present invention can improve the wear resistance inside the ceramic elbow, prevent the ceramic inner lining pipe from being worn through at the turning point under the action of inertia when the flowing medium passes through the turning point of the ceramic inner lining pipe, thereby increasing the service life of the ceramic elbow.

[0019] 2. Through the arc-shaped protrusion provided on the buffer pipe, when the flowing medium enters the ceramic elbow, it first passes through the first straight pipe section, and then sequentially passes through the gentle section, inclined section and arc-shaped protrusion on the inner wall of the buffer pipe and then enters the ceramic inner lining pipe, and then flows out from the second straight pipe section. The arc-shaped protrusion of the buffer pipe can perform pre-buffering before the flowing medium enters the ceramic inner lining pipe, relieve the impact pressure on the ceramic inner lining pipe when the flowing medium changes direction, thereby greatly reducing the impact abrasion on the ceramic inner lining pipe.

[0020] 3. Through the threaded connection and fixation of the threaded sleeve ring, fastening sleeve ring and threaded connection ring, when the flowing medium impacts the arc-shaped protrusion of the buffer pipe, loosening of the connection part of the metal flange can be avoided; through the setting of the sealing gasket, the sealing performance between the threaded connection ring and the fastening sleeve ring can be improved, so that the two metal flanges are connected more tightly, extending the service life of the metal flange; the cooperation of the metal flange and the flange connecting piece makes the maintenance and replacement of the ceramic elbow more convenient, helping to reduce the maintenance cost and time.

[0021] 4. By arranging the ceramic convex sections in multiple numbers and evenly distributing them at the center of the inner cavity of the metal elbow, when the flowing medium passes through the multiple ceramic convex sections, the flowing medium can be shunted, thereby changing the flow path and speed of the flowing medium, reducing local overload, and reducing the impact abrasion of the flowing medium on the ceramic inner lining pipe, preventing the ceramic inner lining pipe from being worn through at the turning point under the action of inertia when the flowing medium passes through the turning point of the ceramic inner lining pipe, thereby increasing the service life of the ceramic elbow. Moreover, the arrangement of multiple ceramic convex sections can reduce the residence time of the flowing medium in the buffer pipe, thereby reducing the risk of blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, other implementation drawings can be obtained according to the provided drawings without creative efforts.

[0023] Figure 1 This figure is a schematic diagram of the connection structure between the metal elbow and the metal flange of a full-bore high-pressure ceramic elbow for oil and gas wellheads according to the present invention;

[0024] Figure 2 This figure is a sectional view of a full-bore high-pressure ceramic elbow for oil and gas wellheads according to the present invention;

[0025] Figure 3 This figure is an exploded schematic diagram of a full-bore high-pressure ceramic elbow for oil and gas wellheads according to the present invention;

[0026] Figure 4 This figure is a sectional view of the internal structure of a full-bore high-pressure ceramic elbow for oil and gas wellheads according to the present invention;

[0027] Figure 5 This figure is a sectional view of the buffer tube according to the present invention;

[0028] Figure 6 This figure is a top view of the buffer tube according to the present invention;

[0029] Figure 7 This figure is a top view of another embodiment of the buffer tube according to the present invention.

[0030] The reference numerals in the figures are respectively represented as follows:

[0031] 1. Metal elbow; 2. Metal flange; 3. Ceramic lining tube; 4. Protrusion; 5. Ceramic elbow section; 6. First straight tube section; 7. Second straight tube section; 8. Buffer tube; 9. Flange connecting piece; 10. Through hole; 11. Tightening screw; 12. Nut; 13. Sealing ring;

[0032] 81. Metal tube; 82. Ceramic protrusion section; 83. Gentle section; 84. Inclined section; 85. Arc-shaped protrusion; 86. Ceramic connecting tube; 91. Tightening collar; 92. Threaded collar; 93. Threaded connecting ring; 94. Sealing gasket. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment 1

[0034] As Figure 1 - Figure 6As shown in the figure, the present invention provides a full-bore high-pressure ceramic elbow for oil and gas wellheads, which includes a metal elbow 1 and a ceramic inner lining pipe 3. It is characterized in that two metal flanges 2 with RJ (Ring-Joint) ring connection surfaces are respectively fixed at both ends of the metal elbow 1. An inner cavity is provided inside the metal elbow 1, and the ceramic inner lining pipe 3 is arranged in the inner cavity. One end of the ceramic inner lining pipe 3 is connected to a buffer pipe 8. The buffer pipe 8 includes a metal pipe 81 and a ceramic protruding section 82. The metal pipe 81 is fixedly arranged inside the inner cavity, and the ceramic protruding section 82 is fixedly sleeved inside the metal pipe 81. A flat section 83, an inclined section 84 and an arc-shaped protrusion 85 are sequentially arranged on the inner side wall of the ceramic protruding section 82. Flange connectors 9 are arranged on both of the two metal flanges 2.

[0035] The ceramic inner lining pipe 3 includes a plurality of angled ceramic elbow segments 5. All the ceramic elbow segments 5 are sequentially arranged along the inside of the inner cavity. A first straight pipe section 6 and a second straight pipe section 7 are respectively arranged at both ends inside the inner cavity. The first straight pipe section 6 is located between the ceramic inner lining pipe 3 and the buffer pipe 8, and one end of the second straight pipe section 7 abuts against the adjacent ceramic elbow segment 5.

[0036] Specifically, a whole ceramic inner lining pipe 3 is cut into a plurality of angled ceramic elbow segments 5. All the ceramic elbow segments 5 are respectively fixed to the center of the inner cavity by gluing. The metal pipe 81 and the ceramic protruding section 82 are sleeved and bonded to form the buffer pipe 8. Then the buffer pipe 8 is bonded at a position close to the ceramic inner lining pipe 3 inside the inner cavity. The first straight pipe section 6 and the second straight pipe section 7 are respectively bonded at both ends inside the inner cavity. Then two metal flanges 2 with RJ ring connection surfaces are welded and fixed at both ends of the metal elbow 1. Through the arrangement of a plurality of ceramic elbow segments 5, the technology of setting a ceramic lining in the metal elbow 1 with an RJ ring connection surface without reducing the diameter is realized, ensuring that the inner diameter of the ceramic inner lining pipe 3 is consistent with the inner diameter of the metal flange 2. By utilizing the natural wear resistance of ceramics, the service life of the metal elbow 1 is improved, and it is especially suitable for being installed at the elbow position on the high-pressure pipelines at oil and gas wellheads that are easily eroded and worn. Through the design of combining metal and ceramic materials, the elbow can work stably in a high-pressure environment, reducing the risk of damage and leakage caused by pressure.

[0037] Among them, when the flowing medium enters the metal elbow 1, it first passes through the first straight pipe section 6, and then successively passes through the gentle section 83, the inclined section 84 and the arc-shaped protrusion 85 on the inner wall of the buffer pipe 8 and then enters the ceramic-lined pipe 3, and then flows out from the second straight pipe section 7. The arc-shaped protrusion 85 of the buffer pipe 8 can perform pre-buffering before the flowing medium enters the ceramic-lined pipe 3, alleviating the impact pressure caused to the ceramic-lined pipe 3 when the flowing medium changes direction, thereby greatly reducing the impact abrasion on the ceramic-lined pipe 3. Further, protrusions 4 are provided at both ends of the ceramic protrusion section 82, and grooves for accommodating the protrusions 4 are provided at one end of the ceramic-lined pipe 3 and one end of the first straight pipe section 6.

[0038] By providing protrusions 4 at both ends of the ceramic protrusion section 82, during installation, the ceramic protrusion section 82, the ceramic-lined pipe 3 and the first straight pipe section 6 are sleeved in sequence and then adhesively fixed to improve the stability of the ceramic protrusion section 82, thereby avoiding problems such as shedding and loosening of the ceramic protrusion section 82 caused by the impact pressure of the flowing medium.

[0039] In the present invention, the setting of multiple ceramic elbow sections 5 can improve the wear resistance inside the ceramic elbow, prevent the ceramic-lined pipe 3 from being worn through at the turning point when the flowing medium flows through the turning point of the ceramic-lined pipe 3 under the action of inertia, thereby improving the service life of the ceramic elbow. The design of the buffer pipe 8, especially the gentle section 83, the inclined section 84 and the arc-shaped protrusion 85 of the ceramic protrusion section 82, provides buffering for the ceramic-lined pipe 3 and reduces the damage that may be caused by the direct impact contact of the flowing medium.

[0040] The gentle section 83 is connected to the second straight pipe section 7, and the arc-shaped protrusion 85 is connected to the ceramic elbow section 5. It is ensured that when the fluid passes through the buffer pipe 8, no diameter reduction will be encountered, thereby maintaining the continuity and efficiency of the fluid flow, reducing the pressure loss, keeping the inside of the metal elbow 1 full-bore, reducing the resistance of the fluid flow, and improving the fluid transportation efficiency.

[0041] The ceramic-lined pipe 3 is cut into several ceramic elbow sections 5 with an angle of α°, and the range of the angle α° is 2° to 20°, optimizing the fluid flow path and reducing the impact of the fluid on the ceramic-lined pipe 3.

[0042] The length of the second straight pipe section 7 is greater than the length of the first straight pipe section 6 to facilitate the installation of the buffer pipe 8.

[0043] Since the buffer tube 8 is arranged near the inlet of one of the metal flanges 2, when the flowing medium impacts the buffer tube 8, it will cause the connection of the metal flange 2 at that place to be impacted and shaken. In order to improve the stability of the connection of the metal flange 2, the flange connecting member 9 is provided to improve the tightness and stability of the connection between the two ceramic elbows. The flange connecting member 9 includes a fastening collar 91, a threaded collar 92, and a threaded connection ring 93. The fastening collar 91 is fixedly sleeved outside the metal flange 2. The threaded collar 92 is threadedly connected to the outer wall of the metal flange 2 of the other ceramic elbow. The threaded connection ring 93 is fixed at one end of the outer wall of the threaded collar 92 close to the fastening collar 91, and the inner diameter of the threaded connection ring 93 is the same as the inner diameter of the threaded collar 92. The threaded connection ring 93 is threadedly connected to the fastening collar 91. A sealing gasket 94 is arranged at the edge of the inner bottom wall of the fastening collar 91, and the sealing gasket 94 is adapted to the threaded connection ring 93.

[0044] A plurality of through holes 10 are all provided through all the metal flanges 2, and all the through holes 10 are uniformly arranged on the inner wall of the metal flange 2 along the circumferential direction. Fastening screws 11 are inserted into all the through holes 10 of one of the metal flanges 2, and one end of all the fastening screws 11 is fixedly connected to one of the metal flanges 2. Nuts 12 are threadedly connected to the other ends of all the fastening screws 11.

[0045] Installation grooves are all formed at the outer extensions of all the metal flanges 2, sealing rings 13 are all arranged on all the installation grooves, and a plurality of through holes for bolts to pass through are formed in the sealing rings 13 along the circumferential direction.

[0046] After matching the sizes of the metal flanges 2 of the two ceramic elbows to be installed and docked, turn the threaded collar 92 on the metal flange 2 of the first ceramic elbow away from the fastening collar 91, then pass the sealing ring 13 through all the fastening screws 11 on the second ceramic elbow and place it in the installation groove. Align the through holes 10 on the metal flange 2 of the first ceramic elbow with all the fastening screws 11 on the second ceramic elbow. Subsequently, rotate the threaded collar 92 so that the threaded collar 92 rotates and tightens along the outside of the metal flange 2 of the first ceramic elbow, driving the threaded connection ring 93 to extend into the fastening collar 91 and threadedly connect and fix with the inner wall of the fastening collar 91 until the threaded connection ring 93 rotates and presses against the gasket 94 to complete the connection of the metal flanges 2 of the two ceramic elbows; further, screw all the nuts 12 onto all the fastening screws 11 one by one to abut and fix the two metal flanges 2 to further fix the two connected metal flanges 2, thereby improving the stability of the connection between the two ceramic elbows. Through the threaded connection and fixation of the threaded collar 92, the fastening collar 91, and the threaded connection ring 93, when the flowing medium impacts the arc-shaped protrusion 85 of the buffer pipe 8, loosening at the connection part of the metal flange 2 can be avoided; through the setting of the gasket 94, the sealing performance between the threaded connection ring 93 and the fastening collar 91 can be improved, so that the two metal flanges 2 are connected more tightly, thereby extending the service life of the metal flange 2; the cooperation between the metal flange 2 and the flange connector 9 makes the maintenance and replacement of the ceramic elbow more convenient, helping to reduce the maintenance cost and time. Embodiment 2

[0047] As Figure 7 shown, on the basis of Embodiment 1, a ceramic connecting pipe 86 is arranged inside the metal pipe 81, and the inner diameter of the ceramic connecting pipe 86 is the same as the inner diameter of the first straight pipe section 6. A plurality of ceramic protrusion sections 82 are provided, and the plurality of ceramic protrusion sections 82 are evenly arranged inside the ceramic connecting pipe 86 in the circumferential direction.

[0048] When the flowing medium enters the ceramic elbow, the flowing medium first enters the first straight pipe section 6, and then successively passes through the gentle section 83, the inclined section 84 and the arc-shaped protrusion 85 on the inner wall of the buffer pipe 8 and then enters the ceramic lining pipe 3, and then flows out from the second straight pipe section 7. By arranging the ceramic protrusion sections 82 in a plurality and evenly distributing them in the ceramic connecting pipe 86, when the flowing medium passes through the plurality of ceramic protrusion sections 82, the flowing medium can be shunted, so as to change the flow path and speed of the flowing medium, reduce local overload, and reduce the impact abrasion of the flowing medium on the ceramic lining pipe 3, preventing the ceramic lining pipe 3 from being worn through at the turning point when the flowing medium flows through the turning point of the ceramic lining pipe 3, thereby improving the service life of the ceramic elbow. Moreover, the arrangement of the plurality of ceramic protrusion sections 82 can reduce the residence time of the flowing medium in the buffer pipe 8, thereby reducing the risk of blockage.

[0049] The scope of protection claimed is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within the essence and scope of protection of this application, and such modifications or equivalent substitutions should also be regarded as falling within the scope of protection of this application.

Claims

1. A full-diameter high-pressure ceramic elbow for oil and gas field wellheads, comprising a metal elbow (1) and a ceramic lined pipe (3), characterized in that: Two metal flanges (2) having RJ ring connection surfaces are fixed at both ends of the metal elbow (1), an inner cavity is provided inside the metal elbow (1), the ceramic lined tube (3) is provided in the inner cavity, one end of the ceramic lined tube (3) is connected to a buffer tube (8), the buffer tube (8) comprises a metal tube (81) and a ceramic raised section (82), the metal tube (81) is fixedly provided inside the inner cavity, the ceramic raised section (82) is fixedly sleeved inside the metal tube (81), a flat section (83), an inclined section (84) and an arc-shaped raised section (85) are provided on the inner side wall of the ceramic raised section (82) in sequence, and flange connectors (9) are provided on both metal flanges (2); The ceramic lined pipe (3) comprises a plurality of ceramic curved pipe sections (5) with angles, all of the ceramic curved pipe sections (5) are arranged in sequence along the inner cavity, a first straight pipe section (6) and a second straight pipe section (7) are arranged at two ends of the inner cavity, the buffer pipe (8) is located between the ceramic lined pipe (3) and the first straight pipe section (6), the flat section (83) is connected to the first straight pipe section (6), and the arc-shaped protrusion (85) is connected to the ceramic curved pipe section (5); A ceramic connecting tube (86) is arranged inside the metal tube (81), and the inner diameter of the ceramic connecting tube (86) is the same as the inner diameter of the first straight tube section (6); a plurality of ceramic protruding sections (82) are arranged, and the plurality of ceramic protruding sections (82) are evenly arranged inside the ceramic connecting tube (86) along a circumferential direction; The flange connection piece (9) comprises a fastening collar (91), a threaded collar (92) and a threaded connection ring (93); the fastening collar (91) is fixedly sleeved on the outside of the metal flange (2); the threaded collar (92) is threadedly connected to the outer wall of the metal flange (2) of another ceramic elbow; the threaded connection ring (93) is fixed to an end of the outer wall of the threaded collar (92) close to the fastening collar (91); the inner diameter of the threaded connection ring (93) is the same as the inner diameter of the threaded collar (92); the threaded connection ring (93) is threadedly connected to the fastening collar (91); a sealing gasket (94) is provided at the edge of the inner bottom wall of the fastening collar (91); the sealing gasket (94) is adapted to the threaded connection ring (93).

2. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 1, characterized in that: One end of the second straight pipe section (7) is in conflict with the adjacent ceramic curved pipe section (5).

3. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 1, characterized in that: All the metal flanges (2) are provided with a plurality of through holes (10), and all the through holes (10) are evenly arranged on the inner wall of the metal flange (2) along the circumferential direction, a fastening screw (11) is inserted into all the through holes (10) on one of the metal flanges (2), and one end of all the fastening screws (11) is fixedly connected to one of the metal flanges (2), and the other end of all the fastening screws (11) is threadedly connected to a nut (12).

4. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 1, characterized in that: All of the metal flanges (2) are provided with mounting grooves at their outer extensions, and all of the mounting grooves are provided with sealing rings (13), and the sealing rings (13) are provided with a plurality of through holes along the circumferential direction for bolts to pass through.

5. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 2, characterized in that: The ceramic lined pipe (3) is cut into a plurality of ceramic curved pipe sections (5) with an angle of α°, and the angle α° ranges from 2° to 20°.

6. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 2, characterized in that: The length of the second straight pipe section (7) is greater than the length of the first straight pipe section (6).

7. The full-diameter high-pressure ceramic elbow for oil and gas field wellhead according to claim 2, characterized in that: Both ends of the ceramic raised section (82) are provided with raised sections (4), and one end of the ceramic lined pipe (3) and one end of the first straight pipe section (6) are provided with grooves for accommodating the raised sections (4).

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