Natural gas expansion type generator

Abstract

The invention provides a natural gas expansion type generator, and relates to the technical field of expansion type power generation. The natural gas expansion type power generator comprises a natural gas inlet pipe, a natural gas outlet pipe, a reversing valve, a three-way connector, a bypass pipe, an expansion machine, a speed reducer, a power generation device, a sucking pump and a recovery tank. According to the natural gas expansion type power generator, an existing natural gas expansion type power generator can be directly modified, leaked natural gas is collected through the sleeve structure and pumped into the recovery tank through the sucking pump, the situation that the natural gas is leaked in a production well station site is avoided, and the field production safety is improved; the natural gas in the sleeve structure jacks up the piston to enter the buffer shell, so that the purpose of rapid pressure relief is achieved, safety is ensured, the natural gas conveying route is changed into the natural gas conveying route through the bypass pipe by arranging the bypass pipe and starting the reversing valve, safety accidents caused by continuous leakage are avoided, and micro-pressure nitrogen is filled in the junction box of the power generation device. And a relatively good explosion-proof effect can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of expansion type power generation, in particular to a natural gas expansion type generator. Background Art

[0002] During the natural gas extraction process, due to the high pressure in the formation, each production well station is directly reduced from high pressure and then transported to a nearby purification plant for treatment. In this gas transmission process, there is natural gas flow and pressure difference, and the pressure difference energy here has great usable value.

[0003] At present, pressure difference energy is mostly used for power generation. An expander is used to pick up the pressure difference energy, and the power shaft drives the reducer, which then drives the generator to generate electricity, thereby converting the pressure difference energy into electrical energy. The same type of power generation equipment mostly adopts the three-level mode of expander + reducer + generator, and the control and power transmission and transformation system constitutes a complete power generation system. However, there is a high-pressure dynamic seal structure between the expander and the reducer. When the pressure at the output end fluctuates greatly, natural gas may leak from the dynamic seal surface to a certain extent, and there is a risk of abnormal leakage;

[0004] To this end, there are public technologies on the market that have proposed improvement plans. The expansion unit adopts a centripetal expander solution. Natural gas enters tangentially from the expansion unit turbine to drive the gas turbine to rotate. At the same time, the gas expansion ratio is guaranteed through reasonable flow channel design. The rotating turbine is directly connected to the generator through a connecting shaft. The generator is built into the high-pressure natural gas shell to achieve built-in power generation, and the electric energy is led out through lead wires. The lead terminals are carefully designed to achieve high-pressure static sealing, so that the external characteristics of the entire device are only: input air inlet, output exhaust port and power and monitoring signal wiring. There are no externally visible rotating parts. This achieves a non-dynamic sealing structure, which solves the risk of leakage to the greatest extent possible.

[0005] The above-mentioned public technology is more suitable for newly built production well stations. However, if it is applied to production well stations that have already been put into production, the original expansion generator must be eliminated, causing great waste. It is necessary to make structural improvements to the natural gas expansion generator that is currently in use to solve the problem of possible leakage at the expansion motor seal when the natural gas transmission pressure fluctuates. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the deficiencies of the prior art, the present invention provides a natural gas expansion generator, which solves the problem of possible leakage at the seal of the expansion motor when the natural gas transmission pressure fluctuates and solves the problem that the existing public technology cannot improve the original expansion generator that has been put into use.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: a natural gas expansion generator, including a natural gas inlet pipe, a natural gas outlet pipe, a reversing valve, a three-way joint, a bypass pipe, an expander, a reducer, a power generation device vacuum pump and a recovery tank, wherein an inlet end is arranged at the top of the expander, and an outlet end and an output end are arranged at the left and right ends of the expander, respectively, an output shaft is arranged on the right side of the output end and the right side of the reducer, an input shaft is arranged on the left side of the reducer and the left side of the power generation device, the output shaft of the output end and the input shaft of the reducer, and the input shaft of the power generation device and the output shaft of the reducer are respectively fixedly connected by a group of couplings, a sleeve structure for sealing the corresponding output shaft and input shaft is also arranged between the output end and the reducer, the interior of the sleeve is in a negative pressure state, the sleeve structure is composed of a first sleeve and a second sleeve, a first sealing structure is arranged between the first sleeve and the output end, and between the second sleeve and the reducer, the first A second sealing structure for sealing is arranged between the opposite ends of the sleeve and the second sleeve, a buffer shell for buffering is arranged jointly on the outer walls of the first sleeve and the second sleeve, the buffer shell is composed of a left shell and a right shell distributed on the left and right, the left shell is fixedly connected to the outer wall of the end of the first sleeve away from the expander, the right shell is fixedly connected to the outer wall of the end of the second sleeve away from the reducer, a third sealing structure for sealing is arranged between the opposite ends of the left shell and the right shell, the circumferential outer walls of the first sleeve and the left shell are both provided with a joint structure for connecting to a vacuum pump, a pressure relief structure for relieving pressure to the buffer shell for buffering when the internal pressure of the sleeve is too large is arranged on the outer wall of the first sleeve and located inside the buffer shell, a junction box is fixedly connected to the upper wall of the power generation device, a plurality of groups of wires are arranged on the rear wall of the junction box, the interior of the junction box is filled with inert gas, and a pressure detection structure for monitoring pressure is arranged on the right wall of the junction box and the outer wall of the first sleeve.

[0010] Preferably, the air inlet end and one end of the bypass pipe are connected to the natural gas inlet pipe through a reversing valve, and the air outlet end and one end of the bypass pipe away from the reversing valve are connected to the natural gas outlet pipe through a three-way joint.

[0011] Preferably, the first sealing structure includes two groups of first sealing rings, and the first and second sleeves are respectively provided with a first fixing seat and a second fixing seat at opposite ends thereof, the first sleeve is fixedly connected to the output end of the expander through the first fixing seat, and the second sleeve is fixedly connected to the end of the reducer facing the expander through the second fixing seat, and a first sealing groove is provided on the side of the first fixing seat facing the output end and on the side of the second fixing seat facing the reducer, the two groups of the first sealing rings are respectively provided on the inner side walls of the two groups of the first sealing grooves, and the first fixing seat and the output end, as well as the second fixing seat and the reducer are sealed respectively by the two groups of first sealing rings.

[0012] Preferably, the second sealing structure includes an outer tube, an inner tube and two groups of second sealing rings, the outer tube and the inner tube are fixedly connected to one end of the second sleeve facing the first sleeve, and the inner tube and the outer tube are respectively located on the inner and outer sides of the second sleeve, the outer tube and the inner tube are both extended toward the left end of the second sleeve and an annular groove is formed between the extended ends, the end of the first sleeve away from the expander is slidably connected to the inner side wall of the annular groove, the inner wall and the outer wall of the end of the first sleeve away from the expander are both provided with a second sealing groove, the two groups of the second sealing rings are respectively sleeved on the inner side walls of the two groups of the second sealing grooves, the two groups of the second sealing rings are respectively slidably connected to the outer wall of the inner tube and the inner side wall of the outer tube on the side away from the first sleeve, and the opposite ends of the first sleeve and the second sleeve are sealed by the outer tube, the inner tube and the two groups of the second sealing rings.

[0013] Preferably, the third sealing structure includes two groups of third sealing rings, and flange edges are provided on the outer wall of the left shell and the outer wall of the right shell and close to the opposite side of the left shell and the right shell. The two groups of third sealing rings are arranged between the two groups of flange edges, and the left shell and the right shell are sealed by the two groups of third sealing rings.

[0014] Preferably, the joint structure includes a first joint and a second joint, the first joint is fixedly connected to the outer wall of the first sleeve, the second joint is fixedly connected to the outer wall of the left shell body, and the end of the first joint away from the first sleeve and the end of the second joint away from the left shell body are both connected to the vacuum pump through a pipeline.

[0015] Preferably, the pressure relief structure includes a connecting seat, a valve housing, a piston and a spring. The connecting seat is fixedly connected to the top of the first sleeve and is located inside the buffer shell. The valve housing is fixedly connected to the end of the connecting seat away from the first sleeve. A through-shaped air vent is arranged inside the connecting seat. The valve housing is connected to the interior of the sleeve structure through the connecting seat. The spring and the piston are arranged in sequence inside the valve housing according to an up and down distribution. A positioning column for maintaining the position of the spring is provided on the upper wall of the piston. The end of the spring facing the piston is sleeved on the outer wall of the positioning column. A plurality of groups of air relief holes are provided on the outer wall of the valve housing. The plurality of groups of air relief holes are distributed up and down and are arranged on the outer wall of the valve housing at equal distances in sequence, and the lowest group of the plurality of air relief holes is close to the lower wall of the valve housing.

[0016] Preferably, the outer wall of the piston is provided with a wear-resistant ring and a fourth sealing ring in sequence from top to bottom, and the outer wall of the wear-resistant ring and the fourth sealing ring are both slidably connected to the inner wall of the valve housing. A sealing sheet for sealing the vent hole is provided at the end of the piston away from the spring, and when the sealing sheet abuts against the lower inner wall of the valve housing, the horizontal height of the fourth sealing ring is located below all the air leakage holes.

[0017] Preferably, the pressure detection structure includes two groups of first pressure sensors and one group of second pressure sensors, the two groups of the first pressure sensors are respectively arranged on the upper wall of the first sleeve and the upper wall of the right shell, and the second pressure sensor is arranged on the right wall of the junction box.

[0018] Preferably, the inert gas inside the junction box is nitrogen, and the nitrogen inside the junction box is in a micro-pressure state.

[0019] (III) Beneficial effects

[0020] The present invention provides a natural gas expansion generator having the following beneficial effects:

[0021] 1. Compared with the existing technology, the natural gas expansion generator can be directly modified on the existing natural gas expansion generator. A casing structure and a buffer shell are set at the connection between the expander and the reducer. When the natural gas transmission pressure fluctuates greatly and causes the expander mechanical seal to leak, the leaked natural gas is collected through the casing structure and pumped into the recovery tank through a vacuum pump, avoiding leakage at the production well station site and improving on-site production safety.

[0022] 2. Compared with the prior art, when the speed of the natural gas leaking into the casing structure is greater than the extraction speed of the vacuum pump and the internal pressure of the casing structure is greater than the elastic force of the spring in the pressure relief structure, the natural gas inside the casing structure will push the piston upward and enter the buffer shell through the air leakage hole to achieve the purpose of rapid pressure relief and ensure safety.

[0023] 3. Compared with the existing technology, the natural gas expansion generator is provided with a bypass pipe. When the pressure inside the casing structure and the buffer shell reaches the upper limit, the reversing valve is activated to change the natural gas transmission route from the expander to the bypass pipe, so as to avoid safety accidents caused by continuous leakage. After the vacuum pump extracts the natural gas inside the casing structure and the buffer shell, power generation can be resumed, thereby achieving better protection.

[0024] 4. Compared with the existing technology, the natural gas expansion generator fills the junction box of the power generation device with micro-pressure nitrogen, which can play a better explosion-proof role. The second pressure sensor is set to monitor the internal pressure of the junction box in real time. When the pressure changes, it means that the sealing of the junction box is damaged. The production well station control equipment can be used to control the shutdown and alarm to facilitate maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is a partial cross-sectional schematic diagram of the connection structure of the expander, reducer and casing structure of the present invention;

[0027] Figure 3For the present invention Figure 2 A partial enlarged view of the middle A;

[0028] Figure 4 For the present invention Figure 2 A partial enlarged view of point B in the middle;

[0029] Figure 5 For the present invention Figure 2 A partial enlarged view of point C in the middle;

[0030] Figure 6 It is a cross-sectional schematic diagram of the pressure relief structure of the present invention.

[0031] Among them, 1. expander; 2. air inlet end; 3. air outlet end; 4. output end; 5. first sleeve; 6. first fixed seat; 7. first joint; 8. second sleeve; 9. second fixed seat; 10. left shell; 11. right shell; 12. second joint; 13. reducer; 14. power generation device; 15. junction box; 16. wire; 17. first pressure sensor; 18. second pressure sensor; 19. first sealing ring; 20. flange edge; 21. third sealing ring; 22. outer pipe; 23. inner pipe; 24. second sealing ring; 25. piston; 26. wear-resistant ring; 27. fourth sealing ring; 28. sealing sheet; 29. ​​positioning column; 30. spring; 31. vent hole; 32. connecting seat; 33. valve housing. DETAILED DESCRIPTION

[0032] 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.

[0033] Example:

[0034] like Figures 1 to 6As shown, an embodiment of the present invention provides a natural gas expansion generator, including a natural gas inlet pipe, a natural gas outlet pipe, a reversing valve, a three-way joint, a bypass pipe, an expander 1, a reducer 13, a power generation device 14, a vacuum pump and a recovery tank. An inlet end 2 is arranged on the top of the expander 1, and an outlet end 3 and an output end 4 are arranged on the left and right ends of the expander 1, respectively. The inlet end 2 and one end of the bypass pipe are connected to the natural gas inlet pipe through the reversing valve, and the outlet end 3 and one end of the bypass pipe away from the reversing valve are connected to the natural gas outlet pipe through the three-way joint. In this embodiment, the expander 1, the reducer 13 and the power generation device 14 maintain the same structure and function as the existing natural gas expansion generator. This embodiment mainly optimizes and improves the existing natural gas expansion generator that has been put into production, and improves the safety of the existing production well station with less labor, facilities and time investment. The bypass pipe is set to switch the natural gas transmission route in an emergency to avoid greater losses, which plays a better protective role.

[0035] like Figure 1 , Figure 2 as well as Figure 3 As shown, in order to seal and protect the reducer 13 and the opposite end of the expander 1, an output shaft is provided on the right side of the output end 4 and the right side of the reducer 13, and an input shaft is provided on the left side of the reducer 13 and the left side of the generator 14. The output shaft of the output end 4 and the input shaft of the reducer 13, and the input shaft of the generator 14 and the output shaft of the reducer 13 are fixedly connected by a group of couplings respectively. A sleeve structure for sealing the corresponding output shaft and input shaft is also provided between the output end 4 and the reducer 13. The interior of the sleeve is in a negative pressure state. The sleeve structure consists of a first sleeve 5 and a second sleeve 8. A first sealing structure is provided between the first sleeve 5 and the output end 4, and between the second sleeve 8 and the reducer 13. The first sealing structure includes two groups of first sealing rings 19. The first sleeve 5 and the second sleeve 8 are respectively fixedly connected to each other. The first fixing seat 6 and the second fixing seat 9 are respectively provided at one end of the back, the first casing 5 is fixedly connected to the output end 4 of the expander 1 through the first fixing seat 6, and the second casing 8 is fixedly connected to the end of the reducer 13 facing the expander 1 through the second fixing seat 9. The first fixing seat 6 is provided with a first sealing groove on one side facing the output end 4 and the second fixing seat 9 is provided with a first sealing groove on one side facing the output end 4. Two groups of first sealing rings 19 are respectively provided on the inner side walls of the two groups of first sealing grooves. The first fixing seat 6 and the output end 4, and the second fixing seat 9 and the reducer 13 are sealed by two groups of first sealing rings 19 respectively, and are connected between the expander 1 and the reducer 13 through a casing joint, so that the internal dynamic seal of the output end 4 of the expander 1 will not directly leak to the production site of the production well station when there is leakage at a large conveying pressure;

[0036] like Figure 1 , Figure 2 as well as Figure 5As shown, a second sealing structure for sealing is provided between the opposite ends of the first sleeve 5 and the second sleeve 8, and the second sealing structure includes an outer tube 22, an inner tube 23 and two sets of second sealing rings 24, the outer tube 22 and the inner tube 23 are fixedly connected to the end of the second sleeve 8 facing the first sleeve 5, and the inner tube 23 and the outer tube 22 are respectively located on the inner and outer sides of the second sleeve 8, the outer tube 22 and the inner tube 23 are extended toward the left end of the second sleeve 8, and an annular groove is formed between the extended ends, the end of the first sleeve 5 away from the expander 1 is slidably connected to the inner side wall of the annular groove, the inner wall and the outer wall of the end of the first sleeve 5 away from the expander 1 are provided with a second sealing groove, and the two The second sealing rings 24 are respectively sleeved on the inner side walls of the two sets of second sealing grooves. The two sets of second sealing rings 24 are slidably connected with the outer wall of the inner tube 23 and the inner side wall of the outer tube 22 on the side away from the first sleeve 5. The first sleeve 5 and the second sleeve 8 are sealed at opposite ends by the outer tube 22, the inner tube 23 and the two sets of second sealing rings 24. The outer tube 22, the inner tube 23 and the annular groove formed by the outer tube 22 and the inner tube 23 are arranged at the left end of the second sleeve 8 to facilitate assembly. If a whole sleeve is used with a long length, assembly and transportation are relatively inconvenient. It is convenient to install and maintain the components in the buffer shell by truncating them in the middle.

[0037] like Figure 1 , Figure 2 as well as Figure 4 As shown, in order to release the pressure in time when the internal pressure of the casing structure is too large, the outer walls of the first casing 5 and the second casing 8 are jointly provided with a buffer shell for buffering, and the buffer shell is composed of a left shell 10 and a right shell 11 distributed on the left and right. The left shell 10 is fixedly connected to the outer wall of the end of the first casing 5 away from the expander 1, and the right shell 11 is fixedly connected to the outer wall of the end of the second casing 8 away from the reducer 13. A third sealing structure for sealing is provided between the opposite ends of the left shell 10 and the right shell 11. The third sealing structure includes two groups of third sealing rings 21. The outer walls of the left shell 10 and the outer walls of the right shell 11 and the opposite sides of the left shell 10 and the right shell 11 are provided with flange edges 20. The two groups of third sealing rings 21 are arranged between the two groups of flange edges 20. The left shell 10 and the right shell 11 are sealed by the two groups of third sealing rings 21. When the internal pressure of the casing structure suddenly increases and the suction speed of the vacuum pump cannot keep up, the internal pressure of the casing structure can be discharged into the buffer shell through the pressure relief structure to improve safety.

[0038] like Figure 1As shown, in order to recover the natural gas inside the casing structure and the buffer shell, the first casing 5 and the outer circumferential wall of the left shell 10 are provided with a joint structure for connecting with the vacuum pump, and the joint structure includes a first joint 7 and a second joint 12. The first joint 7 is fixedly connected to the outer wall of the first casing 5, and the second joint 12 is fixedly connected to the outer wall of the left shell 10. The end of the first joint 7 away from the first casing 5 and the end of the second joint 12 away from the left shell 10 are connected to the vacuum pump through pipelines. The pressure change is measured in real time by the pressure detection structure, and the vacuum pump is controlled to be turned on and off by the pressure detection structure detection signal. After the natural gas enters the buffer shell or the casing structure, it is extracted by the vacuum pump and stored in the recovery tank to avoid direct leakage at the production well station site;

[0039] like Figure 2 , Figure 6 As shown, in order to enable the high pressure in the sleeve structure to be smoothly discharged into the buffer shell, a pressure relief structure for relieving pressure to the buffer shell for buffering when the internal pressure of the sleeve is too large is provided on the outer wall of the first sleeve 5 and located inside the buffer shell. The pressure relief structure includes a connecting seat 32, a valve shell 33, a piston 25 and a spring 30. The connecting seat 32 is fixedly connected to the top of the first sleeve 5 and is located inside the buffer shell. The valve shell 33 is fixedly connected to the end of the connecting seat 32 away from the first sleeve 5. A through-shaped vent hole is provided inside the connecting seat 32. The valve shell 33 is connected to the inside of the sleeve structure through the connecting seat 32. The spring 30 and the piston 25 are sequentially arranged inside the valve shell 33 according to the upper and lower distribution. A positioning column 29 for maintaining the position of the spring 30 is provided on the upper wall of the piston 25. The end of the spring 30 facing the piston 25 is sleeved on the outer wall of the positioning column 29. A plurality of groups of air leakage holes 31 are provided on the outer wall of the valve shell 33. The plurality of groups of air leakage holes 31 are distributed up and down and are arranged on the outer wall of the valve shell 33 at equal distances in sequence, and the lowest group of the plurality of air leakage holes 31 is Close to the lower wall of the valve housing 33, the outer wall of the piston 25 is sequentially provided with a wear-resistant ring 26 and a fourth sealing ring 27 from top to bottom. The outer walls of the wear-resistant ring 26 and the fourth sealing ring 27 are both slidably connected to the inner wall of the valve housing 33. The end of the piston 25 away from the spring 30 is provided with a sealing sheet 28 for blocking the vent hole. When the sealing sheet 28 abuts against the inner lower wall of the valve housing 33, the horizontal height of the fourth sealing ring 27 is located below the air leakage hole 31. When the internal pressure of the sleeve structure is greater than the elastic force of the spring 30 and the air pumping speed cannot keep up, the pressure pushes the piston 25 open, and the piston 25 moves upward to expose the air leakage hole 31. The natural gas inside the sleeve structure enters the buffer shell along the air vent and the air leakage hole 31, which immediately relieves the problem of high pressure inside the sleeve structure. The multiple groups of air leakage holes 31 are distributed up and down. If the dynamic seal is completely damaged, the internal pressure of the sleeve structure increases instantly, and the piston 25 is quickly pushed to the end of the upper stroke. At this time, all the air leakage holes 31 are fully exposed, which can increase the pressure relief speed.

[0040] like Figure 1As shown, in order to perform explosion-proof treatment on the junction box 15, the upper wall of the power generation device 14 is fixedly connected with the junction box 15, and the rear wall of the junction box 15 is provided with multiple sets of wires 16. The inside of the junction box 15 is filled with inert gas, and the inert gas inside the junction box 15 is nitrogen. The nitrogen inside the junction box 15 is in a micro-pressure state. The inside of the junction box 15 is filled with nitrogen, which plays a better explosion-proof protection role;

[0041] like Figure 1 As shown, in order to monitor the internal pressure of the casing structure, the buffer shell and the junction box 15, a pressure detection structure for monitoring the pressure is provided on the right wall of the junction box 15 and the outer wall of the first casing 5. The pressure detection structure includes two groups of first pressure sensors 17 and one group of second pressure sensors 18. The two groups of first pressure sensors 17 are respectively arranged on the upper wall of the first casing 5 and the upper wall of the right shell 11, and the second pressure sensor 18 is arranged on the right wall of the junction box 15. The first pressure sensor 17 on the casing structure is used to control the action of the vacuum pump, and the first pressure sensor 17 on the buffer shell is used to control the reversing valve, that is, when the internal pressure of the buffer shell reaches the upper limit, the reversing valve is started to change the natural gas transmission route to the bypass pipe. The second pressure sensor 18 on the side wall of the junction box 15 is used to monitor the nitrogen storage situation inside the junction box 15, so as to facilitate the confirmation of the sealing state of the junction box 15.

[0042] Working principle: In this embodiment, the expander 1, the reducer 13 and the power generation device 14 are consistent in structure and function with the existing natural gas expansion generator. This embodiment mainly optimizes and improves the existing natural gas expansion generator that has been put into production, and improves the safety of the existing production well station with less labor, facilities and time investment. The bypass pipe is set to switch the natural gas transmission route in an emergency to avoid causing greater losses and play a better protective role. It is connected between the expander 1 and the reducer 13 through a casing joint, so that the output end 4 of the expander 1 is dynamically sealed when the transmission pressure is high. In case of leakage, it will not leak directly to the production site of the production well station. An outer pipe 22, an inner pipe 23 and an annular groove formed by the outer pipe 22 and the inner pipe 23 are arranged at the left end of the second casing 8 to facilitate assembly. If a whole casing is used with a long length, assembly and transportation are relatively inconvenient. The intermediate cut-off form is used to combine them together to facilitate the installation and maintenance of components in the buffer shell. When the internal pressure of the casing structure suddenly increases and the air pumping speed cannot keep up, the internal pressure of the casing structure can be released into the buffer shell through the pressure relief structure to improve safety. The pressure change is measured in real time by the pressure detection structure, and the signal is detected by the pressure detection structure. Control the opening and closing of the vacuum pump. After the natural gas enters the buffer shell or the casing structure, it is extracted by the vacuum pump and stored in the recovery tank to avoid direct leakage at the production well station. When the internal pressure of the casing structure is greater than the elastic force of the spring 30 and the vacuum pump cannot keep up with the suction speed, the pressure pushes open the piston 25, and the piston 25 moves upward to expose the bleed hole 31. The natural gas inside the casing structure enters the buffer shell along the vent hole and the bleed hole 31, which immediately relieves the problem of high pressure inside the casing structure. The multiple groups of bleed holes 31 are distributed up and down. If the dynamic seal is completely damaged, the internal pressure of the casing structure will increase instantly, and the piston 25 is quickly lifted to the end of the upward stroke, at which time all the air vents 31 are fully exposed, which can increase the pressure relief speed. The nitrogen inside the junction box 15 is in a micro-pressure state. The junction box 15 is filled with nitrogen, which plays a good explosion-proof protection role. The first pressure sensor 17 on the casing structure is used to control the action of the vacuum pump. The first pressure sensor 17 on the buffer shell is used to control the reversing valve, that is, when the internal pressure of the buffer shell reaches the upper limit, the reversing valve is started to change the natural gas transmission route to the bypass pipe. The second pressure sensor 18 on the side wall of the junction box 15 is used to monitor the nitrogen storage situation inside the junction box 15, so as to facilitate the confirmation of the sealing state of the junction box 15.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Natural gas expansion generator, characterized by: The invention comprises a natural gas inlet pipe, a natural gas outlet pipe, a reversing valve, a three-way joint, a bypass pipe, an expander (1), a reducer (13), a power generation device (14), a vacuum pump and a recovery tank. The expander (1) is provided with an inlet end (2) at the top, and the expander (1) is provided with an outlet end (3) and an output end (4) at the left and right ends respectively. The right side of the output end (4) and the right side of the reducer (13) are both provided with an output shaft. The left side of the reducer (13) and the left side of the power generation device (14) are both provided with an input shaft. The output shaft of the output end (4) is connected to the reducer (13). The input shafts, the input shaft of the power generation device (14) and the output shaft of the reducer (13) are respectively fixedly connected by a set of couplings. A sleeve structure for sealing the corresponding output shaft and input shaft is also provided between the output end (4) and the reducer (13). The interior of the sleeve is in a negative pressure state. The sleeve structure consists of a first sleeve (5) and a second sleeve (8). A first sealing structure is provided between the first sleeve (5) and the output end (4) and between the second sleeve (8) and the reducer (13). The first sleeve (5) and the second sleeve (8) have opposite ends. A second sealing structure for sealing is arranged between the first casing (5) and the second casing (8); a buffer shell for buffering is arranged on the outer walls of the first casing (5) and the second casing (8); the buffer shell is composed of a left casing (10) and a right casing (11) which are distributed on the left and the right; the left casing (10) is fixedly connected to the outer wall of one end of the first casing (5) away from the expander (1); the right casing (11) is fixedly connected to the outer wall of one end of the second casing (8) away from the reducer (13); a third sealing structure for sealing is arranged between the opposite ends of the left casing (10) and the right casing (11); The first sleeve (5) and the circumferential outer wall of the left shell (10) are both provided with a joint structure for connecting to an air pump; the outer wall of the first sleeve (5) and the interior of the buffer shell are provided with a pressure relief structure for relieving pressure to the buffer shell for buffering when the pressure inside the sleeve is too high; the upper wall of the power generation device (14) is fixedly connected with a junction box (15); the rear wall of the junction box (15) is provided with a plurality of groups of wires (16); the interior of the junction box (15) is filled with an inert gas; the right wall of the junction box (15) and the outer wall of the first sleeve (5) are provided with a pressure detection structure for monitoring pressure.

2. The natural gas expansion generator according to claim 1, characterized in that: The air inlet end (2) and one end of the bypass pipe are connected to the natural gas inlet pipe via a reversing valve, and the air outlet end (3) and one end of the bypass pipe away from the reversing valve are connected to the natural gas outlet pipe via a three-way joint.

3. The natural gas expansion generator according to claim 2, characterized in that: The first sealing structure comprises two groups of first sealing rings (19); a first fixing seat (6) and a second fixing seat (9) are respectively arranged at opposite ends of the first sleeve (5) and the second sleeve (8); the first sleeve (5) is fixedly connected to the output end (4) of the expander (1) through the first fixing seat (6); the second sleeve (8) is fixedly connected to the end of the reducer (13) facing the expander (1) through the second fixing seat (9); a first sealing groove is arranged on the side of the first fixing seat (6) facing the output end (4) and the side of the second fixing seat (9) facing the reducer (13); the two groups of the first sealing rings (19) are respectively arranged on the inner side walls of the two groups of the first sealing grooves; the first fixing seat (6) and the output end (4) and the second fixing seat (9) and the reducer (13) are respectively sealed by the two groups of the first sealing rings (19).

4. The natural gas expansion generator according to claim 3, characterized in that: The second sealing structure comprises an outer tube (22), an inner tube (23) and two sets of second sealing rings (24); the outer tube (22) and the inner tube (23) are both fixedly connected to one end of the second sleeve (8) facing the first sleeve (5); the inner tube (23) and the outer tube (22) are respectively located on the inner and outer sides of the second sleeve (8); the outer tube (22) and the inner tube (23) are both extended toward the left end of the second sleeve (8) and an annular groove is formed between the extended ends; the end of the first sleeve (5) away from the expander (1) is in contact with the inner groove; The side walls are slidably connected, the inner wall and the outer wall of the end of the first sleeve (5) away from the expander (1) are both provided with a second sealing groove, and two groups of the second sealing rings (24) are respectively sleeved on the inner side walls of the two groups of second sealing grooves, and the two groups of the second sealing rings (24) are slidably connected to the outer wall of the inner edge tube (23) and the inner side wall of the outer edge tube (22) on the side away from the first sleeve (5), and the first sleeve (5) and the second sleeve (8) are sealed between the opposite ends by the outer edge tube (22), the inner edge tube (23) and the two groups of the second sealing rings (24).

5. The natural gas expansion generator according to claim 4, characterized in that: The third sealing structure comprises two groups of third sealing rings (21); flange edges (20) are arranged on the outer wall of the left shell (10) and the outer wall of the right shell (11) and close to the left shell (10) and the right shell (11) on the opposite side; the two groups of third sealing rings (21) are arranged between the two groups of flange edges (20); and the left shell (10) and the right shell (11) are sealed by the two groups of third sealing rings (21).

6. The natural gas expansion generator according to claim 5, characterized in that: The joint structure comprises a first joint (7) and a second joint (12); the first joint (7) is fixedly connected to the outer wall of the first sleeve (5); the second joint (12) is fixedly connected to the outer wall of the left shell (10); an end of the first joint (7) away from the first sleeve (5) and an end of the second joint (12) away from the left shell (10) are both connected to the air pump via a pipeline.

7. The natural gas expansion generator according to claim 6, characterized in that: The pressure relief structure comprises a connecting seat (32), a valve housing (33), a piston (25) and a spring (30); the connecting seat (32) is fixedly connected to the top of the first sleeve (5) and is located inside the buffer housing; the valve housing (33) is fixedly connected to an end of the connecting seat (32) away from the first sleeve (5); a through-shaped vent hole is arranged inside the connecting seat (32); the valve housing (33) is connected to the inside of the sleeve structure through the connecting seat (32); the spring (30), the piston (25) and the spring (30) are connected to the top of the first sleeve (5) and are located inside the buffer housing; the valve housing (33) is fixedly connected to the ... the valve housing (33) is connected to the inside of the sleeve structure through the connecting seat (32); the spring (30), the piston (25) and the spring (30) are connected to the piston (25) ) are arranged in sequence in an up-and-down distribution inside the valve housing (33); a positioning column (29) for maintaining the position of the spring (30) is arranged on the upper wall of the piston (25); one end of the spring (30) facing the piston (25) is sleeved on the outer wall of the positioning column (29); a plurality of groups of air leakage holes (31) are arranged on the outer wall of the valve housing (33); the plurality of groups of air leakage holes (31) are arranged in sequence on the outer wall of the valve housing (33) in an up-and-down distribution and at equal distances; and the lowest group of the plurality of air leakage holes (31) is close to the lower wall of the valve housing (33).

8. The natural gas expansion generator according to claim 7, characterized in that: The outer wall of the piston (25) is provided with a wear-resistant ring (26) and a fourth sealing ring (27) in sequence from top to bottom. The outer walls of the wear-resistant ring (26) and the fourth sealing ring (27) are both slidably connected to the inner wall of the valve housing (33). The end of the piston (25) away from the spring (30) is provided with a sealing sheet (28) for sealing the vent hole. When the sealing sheet (28) is in contact with the lower inner wall of the valve housing (33), the fourth sealing ring (27) is located at a level below all the air leakage holes (31).

9. The natural gas expansion generator according to claim 8, characterized in that: The pressure detection structure comprises two groups of first pressure sensors (17) and one group of second pressure sensors (18), the two groups of the first pressure sensors (17) being respectively arranged on the upper wall of the first sleeve (5) and the upper wall of the right shell (11), and the second pressure sensor (18) being arranged on the right wall of the junction box (15).

10. The natural gas expansion generator according to claim 9, characterized in that: The inert gas inside the junction box (15) is nitrogen, and the nitrogen inside the junction box (15) is in a micro-pressure state.

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