A skid-mounted device and method for generating electricity by using the pressure difference of high-pressure natural gas in oil and gas fields

Abstract

The present invention provides a skid-mounted device and method for generating electricity using the pressure differential of high-pressure natural gas in oil and gas fields. The device relates to natural gas gathering and transportation technology. The device includes a thermometer for detecting the temperature of the high-pressure natural gas at the wellhead, an expansion generator connected to the rear end of the thermometer, and a heat exchange tube assembly located within a heating furnace. The pipeline between the thermometer and the expansion generator is provided with valves a located at the rear end of the thermometer and valve c located at the front end of the expansion generator. The rear end of the expansion generator is connected to a pressure-reducing natural gas transmission pipeline b and an external power transmission cable. Valve b is provided on the pipeline between the thermometer and the inlet end of the heat exchange tube assembly. The outlet end of the heat exchange tube assembly is connected to the pipeline behind valve a. The pipeline between valves a and c is connected to a pressure-reducing natural gas transmission pipeline a. Valve d and a pressure regulating valve are provided on the pressure-reducing natural gas transmission pipeline a. The present invention can reduce the pressure of high-pressure natural gas and fully recover the pressure energy of the high-pressure natural gas.

Description

Technical Field

[0001] The present invention belongs to the field of natural gas production in oil and gas fields and relates to natural gas gathering and transportation technology, specifically a skid-mounted device and method for generating electricity by utilizing the pressure difference of high-pressure natural gas in oil and gas fields. Background Art

[0002] When producing natural gas in oil and gas fields, high formation pressures in the wells result in high pressure at the outlet. To gather and transport the natural gas, it is typically throttled and depressurized before entering the gas pipeline network for gathering and transportation. While this method can reduce the natural gas pressure, it fails to effectively utilize the inherent pressure energy of the high-pressure natural gas. Summary of the Invention

[0003] In order to overcome the defect of existing natural gas gathering and transportation methods that cannot effectively utilize the pressure energy of high-pressure natural gas, the present invention provides a skid-mounted device and method for generating electricity by utilizing the pressure difference of high-pressure natural gas in oil and gas fields. The device can reduce the pressure of high-pressure natural gas to low-pressure natural gas, realize the grid-connected gathering and transportation of natural gas, and can fully recover the pressure energy of high-pressure natural gas and convert it into electrical energy for external output.

[0004] The technical solution adopted by the present invention to solve its technical problems is:

[0005] A skid-mounted device for generating electricity using the pressure differential of high-pressure natural gas in an oil and gas field, comprising a thermometer for detecting the temperature of the high-pressure natural gas at a wellhead, an expansion generator connected to the rear end of the thermometer, and a heat exchange tube assembly disposed within a heating furnace; the pipeline between the thermometer and the expansion generator is provided with a valve a located at the rear end of the thermometer and a valve c located at the front end of the expansion generator, the rear end of the expansion generator being connected to a pressure-reducing natural gas transmission pipeline b and an external power transmission cable; the pipeline between the thermometer and the air inlet end of the heat exchange tube assembly is provided with a valve b, the air outlet end pipeline of the heat exchange tube assembly is connected to the pipeline at the rear end of valve a, the pipeline between valves a and c is connected to the pressure-reducing natural gas transmission pipeline a, and the pressure-reducing natural gas transmission pipeline a is provided with a valve d and a pressure regulating valve.

[0006] Furthermore, an electric heater for heating the high-pressure natural gas in the heat exchange tube assembly is provided in the heating furnace; a branch cable is connected to the external power transmission cable, and the branch cable is connected to the electric heater.

[0007] Furthermore, the heating furnace is also provided with a heating furnace fire tube for heating the high-pressure natural gas in the heat exchange tube assembly, and the heating furnace fire tube is connected to the gas burner provided outside the heating furnace; a branch pipeline is connected to the pressure-reducing natural gas transmission pipeline a, and the branch pipeline is connected to the gas burner.

[0008] Furthermore, a valve e is provided on the branch pipeline.

[0009] Furthermore, a filter is provided at the front end of the thermometer.

[0010] A method for generating electricity by utilizing the pressure difference of high-pressure natural gas in an oil and gas field. Using the above-mentioned skid-mounted device, the high-pressure natural gas at the wellhead first enters a filter to remove solid particles and liquid droplets, and then is detected by a thermometer. When the temperature of the high-pressure natural gas detected by the thermometer is high, valve b is closed, valve a is opened, valve d is closed, and valve c is opened, and the high-pressure natural gas enters an expansion generator. After the pressure of the high-pressure natural gas is reduced by the expansion generator, it is transmitted to the pipeline network through the reduced-pressure natural gas transmission pipeline b; the high-pressure natural gas drives the expansion generator to generate electricity by pressure difference, and the generated electricity is transmitted to the power grid through an external transmission cable.

[0011] Furthermore, when the temperature of the high-pressure natural gas detected by the thermometer is medium, valve b is opened, valve a is closed, valve d is closed, and valve c is opened. The high-pressure natural gas enters the heat exchange tube assembly of the heating furnace through valve b for heating. After leaving the heating furnace, it enters the expansion generator through valve c. After the pressure of the high-pressure natural gas is reduced by the expansion generator, it is transported out into the pipeline network through the reduced-pressure natural gas transmission pipeline b; the high-pressure natural gas drives the expansion generator to generate electricity through the pressure difference, and the generated electricity is transported out into the power grid through the external transmission cable.

[0012] Furthermore, the electric energy generated by the pressure difference power generation driven by the expansion generator driven by high-pressure natural gas can also enter the electric heater in the heating furnace through the branch cable connected to the external transmission cable to heat the high-pressure natural gas in the heat exchange tube assembly, thereby heating the high-pressure natural gas from medium temperature to high temperature.

[0013] Furthermore, when the high-pressure natural gas temperature detected by the thermometer is low, valve b is opened, valve a is closed, valve d is opened, and valve c is closed. The high-pressure natural gas passes through valve b and enters the heat exchange tube assembly of the heating furnace for heating. After leaving the heating furnace, it passes through valve d and is throttled and reduced in pressure by the pressure regulating valve before being transported out through the pressure-reduced natural gas transmission pipeline a into the pipeline network.

[0014] Furthermore, after the high-pressure natural gas is throttled and reduced in pressure by the pressure regulating valve, it can also be supplied to the gas burner through the branch pipeline connected to the pressure-reducing natural gas transmission pipeline a, and then enter the heating furnace fire tube in the heating furnace for combustion to heat the high-pressure natural gas in the heat exchange tube assembly.

[0015] The beneficial effects of this invention include: not only can it reduce the pressure of high-pressure natural gas at the wellhead, reducing it to low-pressure natural gas, thus enabling grid-connected natural gas collection and transmission, but it also uses an expansion generator to generate power using the pressure difference of high-pressure natural gas, fully recovering the pressure energy of the high-pressure natural gas and converting it into electrical energy for external output. It can also be skid-mounted and integrated, making it easy to relocate and reducing space requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a schematic diagram of the overall structure of a skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields according to the present invention;

[0017] Figure 2 It is a schematic diagram of the internal damper structure of the heat exchange tube assembly.

[0018] In the figure: 1. High-pressure natural gas; 2. Filter; 3. Heating furnace; 4. Heat exchange tube assembly; 5. Electric heater; 6. Heating furnace fire tube; 7. Gas burner; 8. Branch cable; 9. Pressure-reduced natural gas transmission pipeline a; 10. Pressure-reduced natural gas transmission pipeline b; 11. External transmission cable; 12. Expansion generator; 13. Valve c; 14. Valve d; 15. Pressure regulating valve; 16. Valve a; 17. Valve b; 18. Thermometer; 19. Valve e; 20. Branch pipeline. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] A skid-mounted device and method for generating electricity using the pressure difference of high-pressure natural gas in an oil and gas field. The high-pressure natural gas 1 coming out of the wellhead of the oil and gas field is depressurized and then enters an external natural gas pipeline.

[0022] refer to Figure 1 The specific steps are as follows: Wellhead high-pressure natural gas 1 first enters filter 2 to remove solid particles and liquid droplets in the natural gas. It is then tested by thermometer 18. If the temperature reaches "high," valve b17 closes, valve a16 opens, valve d14 closes, and valve c13 opens. The high-pressure natural gas 1 then enters expansion generator 12 (the expander drives the generator). After the high-pressure natural gas passes through expansion generator 12, not only is its pressure reduced, but it also generates power by driving expansion generator 12. The generated electricity is then transmitted to the power grid via external transmission cable 11. The reduced-pressure natural gas from expansion generator 12 is then transported to the pipeline network via reduced-pressure natural gas transmission pipeline b10, achieving natural gas collection and transportation after it has been reduced in pressure.

[0023] High-pressure natural gas 1 is tested by thermometer 18. If the temperature reaches "medium temperature," valve b17 opens, valve a16 closes, valve d14 closes, and valve c13 opens, allowing the high-pressure natural gas to enter the heat exchange tube assembly 4 of the heating furnace 3. After being heated to a certain temperature in the heat exchange tube assembly 4, the high-pressure natural gas leaves the heating furnace and passes through valve c13 into the expansion generator 12. Passing through the expansion generator 12, the high-pressure natural gas not only experiences a reduction in pressure but also generates power by driving the expansion generator. The generated electricity can be transmitted to the power grid via external transmission cable 11 and then, via branch cable 8, to the electric heater 5 in the heating furnace 3 to heat the high-pressure natural gas in the heat exchange tube assembly 4, heating it from medium temperature to high temperature. The reduced-pressure natural gas from the expansion generator 12 is then transported to the pipeline network via reduced-pressure natural gas transmission pipeline b10, achieving natural gas collection and transportation after pressure reduction.

[0024] High-pressure natural gas 1 is tested by thermometer 18. If the temperature reaches "low," valve b17 opens, valve a16 closes, valve d14 opens, and valve c13 closes, allowing the high-pressure natural gas to enter the heat exchange tube assembly 4 of the heating furnace 3. After being heated to a certain temperature in the heat exchange tube assembly 4, the high-pressure natural gas leaves the heating furnace, passes through valve d14, and then through pressure regulating valve 15 to reduce its pressure. The reduced-pressure natural gas is then transported through reduced-pressure natural gas transmission pipeline a9 into the pipeline network, achieving reduced-pressure natural gas collection and transportation. Simultaneously, a branch pipeline 20 can be introduced to carry the reduced-pressure natural gas through valve e19 and then to the gas burner 7, where it is burned in the furnace's flame tube 6, heating the high-pressure natural gas in the heat exchange tube assembly 4.

[0025] It should be noted that the "high temperature", "medium temperature" and "low temperature" mentioned in the above embodiment may have different temperature ranges depending on the pressure drop of the expansion generator 12. For example, when the high-pressure natural gas has a pressure drop of 2 MPa and a temperature drop of 35°C after passing through the expansion generator, the high-pressure natural gas is considered high temperature if it exceeds 40°C, medium temperature if it is between 20°C and 40°C, and low temperature if it is below 20°C.

[0026] Preferably, Figure 2 As shown, the heat exchange tube assembly 4 in the heating furnace 3 is installed with an 8-shaped twist damper internal component that can enhance the heat exchange efficiency. This internal component can not only increase the heat exchange area, improve the heat exchange efficiency, reduce the amount of steel pipes used, and save costs, but also increase the friction coefficient of natural gas in the heat exchange tube assembly, increase the frictional heat generated by natural gas, reduce the load of the heating furnace, and reduce the energy consumption of the heating furnace.

[0027] Example 1:

[0028] 100000Nm at a pressure of 4MPa 3 / h high-pressure natural gas 1 at the wellhead first enters filter 2 to remove solid particles and liquid droplets. It then passes through thermometer 18, where its temperature is measured at 40°C. Valve b17 closes, valve a16 opens, valve d14 closes, and valve c13 opens, allowing the high-pressure natural gas to enter expander generator 12, which has a pressure ratio of 2. After passing through the expander generator, the pressure of the high-pressure natural gas drops to 2 MPa and the temperature drops to 5°C, generating approximately 1200 kW of electricity. This 1200 kW of electricity is then transmitted to the power grid via transmission cable 11. The reduced-pressure natural gas is then transported to the pipeline network via reduced-pressure natural gas transmission pipeline b10, completing the collection and transportation of reduced-pressure natural gas.

[0029] Example 2:

[0030] 100000Nm at a pressure of 4MPa 3 / hThe wellhead high-pressure natural gas 1 first enters the filter 2 to remove solid particles and droplets in the natural gas. It is then tested by the thermometer 18 and its temperature is detected to be 30°C. Then valve b17 is opened, valve a16 is closed, valve d14 is closed, and valve c13 is opened. The high-pressure natural gas enters the heat exchange tube assembly 4 of the heating furnace 3. After being heated to 40°C in the heat exchange tube assembly 4, the high-pressure natural gas leaves the heating furnace and enters the expansion generator 12 with a pressure ratio of 2 through valve c13. After passing through the expansion generator, the pressure of the high-pressure natural gas drops to 2MPa and the temperature drops to 5°C. The power generation capacity is approximately 1200kW. Of the 1200kW of electrical energy generated, approximately 400kW of electrical energy enters the electric heater 5 in the heating furnace 3 through the branch cable 8 to heat the high-pressure natural gas in the heat exchange tube assembly 4, heating the high-pressure natural gas from 30°C to 40°C. The remaining 800kW of electrical energy is transmitted to the power grid through the external transmission cable 11. The reduced-pressure natural gas is transported from the reduced-pressure natural gas transmission pipeline b10 into the pipeline network, realizing the gathering and transportation of natural gas after pressure reduction.

[0031] Example 3:

[0032] 100000Nm at a pressure of 4MPa 3 / h High-pressure natural gas 1 at the wellhead first enters filter 2 to remove solid particles and liquid droplets. It then passes through thermometer 18, detecting a temperature of 5°C. Valve b17 is then opened, valve a16 is closed, valve d14 is opened, and valve c13 is closed. The high-pressure natural gas then enters the heat exchange tube assembly 4 of the heating furnace 3. After being heated to 15°C in the heat exchange tube assembly 4, it leaves the furnace, passes through valve d14, and then through pressure regulating valve 15, where it is throttled down to 2 MPa. The reduced-pressure natural gas is then transported through reduced-pressure natural gas transmission pipeline a9 into the pipeline network, achieving reduced-pressure natural gas collection and transportation. Simultaneously, a branch pipeline 20 can be introduced to carry the reduced-pressure natural gas through valve e19 and then to the gas burner 7, where it is burned in the furnace's flame tube 6, heating the high-pressure natural gas in the heat exchange tube assembly 4.

[0033] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields, characterized in that: The invention comprises a thermometer (18) for detecting the temperature of the high-pressure natural gas at the wellhead, an expansion generator (12) respectively connected to the rear end of the thermometer (18), and a heat exchange tube assembly (4) arranged in the heating furnace (3); a valve a (16) located at the rear end of the thermometer (18) and a valve c (13) located at the front end of the expansion generator (12) are respectively provided on the pipeline between the thermometer (18) and the expansion generator (12); the rear end of the expansion generator (12) is respectively connected to the pressure-reducing natural gas transmission pipeline b (10) and the external transmission cable (11); a valve b (17) is provided on the pipeline between the thermometer (18) and the air inlet end of the heat exchange tube assembly (4); the air outlet end pipeline of the heat exchange tube assembly (4) is connected to the pipeline at the rear end of the valve a (16); the pipeline between the valve a (16) and the valve c (13) is connected to the pressure-reducing natural gas transmission pipeline a (9); the pressure-reducing natural gas transmission pipeline a (9) is respectively provided with a valve d (14) and a pressure regulating valve (15); The heating furnace (3) is further provided with an electric heater (5) for heating the medium- and high-pressure natural gas in the heat exchange tube assembly (4); a branch cable (8) is connected to the external power transmission cable (11), and the branch cable (8) is connected to the electric heater (5); the heating furnace (3) is further provided with a heating furnace fire tube (6) for heating the medium- and high-pressure natural gas in the heat exchange tube assembly (4), and the heating furnace fire tube (6) is connected to a gas burner (7) provided outside the heating furnace (3); a branch pipeline (20) is connected to the pressure-reducing natural gas transmission pipeline a (9), and the branch pipeline (20) is connected to the gas burner (7); a valve e (19) is provided on the branch pipeline (20); The method for generating power by using the pressure difference of high-pressure natural gas in the oil and gas field based on the skid-mounted device is as follows: the high-pressure natural gas at the wellhead first enters the filter (2) to remove solid particles and liquid droplets, and then is detected by the thermometer (18). When the temperature of the high-pressure natural gas detected by the thermometer (18) is medium temperature, the valve b (17) is opened, the valve a (16) is closed, the valve d (14) is closed, and the valve c (13) is opened. The high-pressure natural gas passes through the valve b (17) and enters the heat exchange tube assembly (4) of the heating furnace (3) for heating. After leaving the heating furnace (3), the high-pressure natural gas passes through the valve c (13) and enters the expansion generator ( 12), after the high-pressure natural gas is reduced in pressure by the expansion generator (12), it is transported outwards through the pressure-reducing natural gas transmission pipeline b (10) into the pipeline network; the high-pressure natural gas drives the expansion generator (12) to generate power by pressure difference, and the generated electric energy is transported outwards through the external transmission cable (11) into the power grid; the electric energy generated by the pressure difference generation by the expansion generator (12) driven by the high-pressure natural gas also enters the electric heater (5) in the heating furnace (3) through the branch cable (8) connected to the external transmission cable (11), so as to heat the high-pressure natural gas in the heat exchange tube assembly (4), thereby heating the high-pressure natural gas from medium temperature to high temperature; The "high temperature", "medium temperature" and "low temperature" of high pressure natural gas are specifically: when the pressure drop of high pressure natural gas is 2MPa and the temperature drop is 35℃ after passing through the expansion generator (12), the high pressure natural gas is high temperature when it exceeds 40℃, medium temperature when it is between 20℃ and 40℃, and low temperature when it is below 20℃.

2. The skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields according to claim 1 is characterized in that: A filter (2) is provided at the front end of the thermometer (18).

3. The skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields according to claim 1 is characterized in that: The high-pressure natural gas at the wellhead first enters the filter (2) to remove solid particles and liquid droplets, and then is detected by the thermometer (18). When the temperature of the high-pressure natural gas detected by the thermometer (18) is high, valve b (17) is closed, valve a (16) is opened, valve d (14) is closed, and valve c (13) is opened. The high-pressure natural gas enters the expansion generator (12). After the pressure of the high-pressure natural gas is reduced by the expansion generator (12), it is transported to the pipeline network through the pressure-reducing natural gas transmission pipeline b (10); the high-pressure natural gas drives the expansion generator (12) to generate power by pressure difference, and the generated electricity is transported to the power grid through the external transmission cable (11).

4. The skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields according to claim 3 is characterized in that: When the high-pressure natural gas temperature detected by the thermometer (18) is low, valve b (17) is opened, valve a (16) is closed, valve d (14) is opened, and valve c (13) is closed. The high-pressure natural gas passes through valve b (17) and enters the heat exchange tube assembly (4) of the heating furnace (3) for heating. After leaving the heating furnace (3), it passes through valve d (14) and is throttled and depressurized by the pressure regulating valve (15). After that, it is transported out through the pressure-reduced natural gas transmission pipeline a (9) and into the pipeline network.

5. The skid-mounted device for generating electricity using the pressure difference of high-pressure natural gas in oil and gas fields according to claim 4 is characterized in that: After the high-pressure natural gas is throttled and reduced in pressure by the pressure regulating valve (15), it can also be supplied to the gas burner (7) through the branch pipeline (20) connected to the pressure-reducing natural gas transmission pipeline a (9), and then enter the heating furnace fire tube (6) in the heating furnace (3) for combustion, thereby heating the high-pressure natural gas in the heat exchange tube assembly (4).

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