A method and system for residual pressure power generation in high-pressure natural gas dehydration treatment

Abstract

The present invention relates to the technical field of high-pressure natural gas dehydration treatment, and provides a residual pressure power generation method and system for high-pressure natural gas dehydration treatment. The method includes the following steps: dehydrating the produced high-pressure natural gas; utilizing the expanded work of the dehydrated high-pressure natural gas to utilize the pressure energy in the high-pressure natural gas; reheating the expanded low-temperature natural gas. The residual pressure power generation method for high-pressure natural gas dehydration treatment provided by the present invention first dehydrates the produced high-pressure natural gas; then, utilizes the expanded work of the dehydrated high-pressure natural gas to utilize the pressure energy in the high-pressure natural gas; finally, reheats the expanded low-temperature natural gas. After dehydration, the dew point temperature of the natural gas can meet the requirements of long-distance pipelines, and the pressure energy in the high-pressure natural gas can be effectively utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of high-pressure natural gas dehydration treatment, and particularly relates to a residual pressure power generation method and system for high-pressure natural gas dehydration treatment. Background Art

[0002] The high-pressure natural gas produced from oil fields often contains a large amount of saturated water. When the pipeline transportation temperature is lower than its dew point temperature, water will precipitate. On the one hand, it will block the flow area in the pipeline and form an ice blockage in severe cases; on the other hand, it will corrode the pipeline by reacting with the unremoved acidic components, affecting the normal progress of natural gas extraction and transportation. Therefore, natural gas dehydration treatment is an important process before the oil field produced gas enters the long-distance pipeline.

[0003] Currently, J-T valve low-temperature separation is often used for high-pressure natural gas dehydration treatment, which has the advantages of low operating cost and simple process compared with triethylene glycol dehydration and molecular sieve dehydration. However, after dehydration by this method, the dew point temperature of natural gas still cannot meet the requirements of long-distance pipelines, and the pressure energy in high-pressure natural gas cannot be effectively utilized. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that after dehydration by the existing high-pressure natural gas dehydration treatment method, the dew point temperature of natural gas still cannot meet the requirements of long-distance pipelines, and the pressure energy in high-pressure natural gas cannot be effectively utilized. Thus, a residual pressure power generation method and system for high-pressure natural gas dehydration treatment are provided.

[0005] To solve the above technical problem, the technical solution of the present invention is as follows:

[0006] A residual pressure power generation method for high-pressure natural gas dehydration treatment includes the following steps: dehydrating the produced high-pressure natural gas; utilizing the expanded work of the dehydrated high-pressure natural gas to utilize the pressure energy in the high-pressure natural gas; reheating the expanded low-temperature natural gas.

[0007] Further, before dehydrating the produced high-pressure natural gas: first, use the expanded low-temperature natural gas to cool the produced high-pressure natural gas to achieve the first reheating of the expanded low-temperature natural gas and pre-cool the produced high-pressure natural gas.

[0008] Further, perform the first gas-liquid separation on the pre-cooled high-pressure natural gas to remove the moisture in the high-pressure natural gas.

[0009] Further, before utilizing the expanded work of the dehydrated high-pressure natural gas, reheat the high-pressure natural gas after the first gas-liquid separation.

[0010] Further, before the first rewarming of the expanded low-temperature natural gas, a second gas-liquid separation is performed on the expanded low-temperature natural gas.

[0011] Further, when the dehydrated high-pressure natural gas expands to do work, the heat generated by the expansion work is used to perform a second rewarming on the low-temperature natural gas after the first rewarming.

[0012] Further, the dehydrated high-pressure natural gas is used to expand and do work, and the output work of the expansion is used for power generation.

[0013] A residual pressure power generation system for high-pressure natural gas dehydration treatment, comprising: a dehydration unit adapted to dehydrate the produced high-pressure natural gas; an expansion work unit connected to the dehydration unit and adapted to use the dehydrated high-pressure natural gas to expand and do work to utilize the pressure energy in the high-pressure natural gas; a rewarming unit connected to both the dehydration unit and the expansion work unit and adapted to rewarm the expanded low-temperature natural gas.

[0014] Further, the dehydration unit includes a first heat exchanger and a first separator connected to each other; the first heat exchanger is adapted to pre-cool and cool down the produced high-pressure natural gas; the first separator is adapted to perform a first gas-liquid separation on the pre-cooled and cooled high-pressure natural gas.

[0015] Further, the expansion work unit includes an expander, a gearbox, and a generator connected to each other, and both the first separator and the first heat exchanger are connected to the expander; in the expander, the dehydrated high-pressure natural gas expands to do work, converting the pressure energy in the high-pressure natural gas into mechanical energy; in the generator, the mechanical energy is converted into electrical energy.

[0016] Further, the rewarming unit includes a first heat exchanger and a second heat exchanger connected to each other; the first heat exchanger is adapted to perform a first rewarming on the expanded low-temperature natural gas; the second heat exchanger is adapted to perform a second rewarming on the low-temperature natural gas after the first rewarming.

[0017] Further, the dehydration unit further includes a second separator disposed between the expander and the first heat exchanger; the second separator is adapted to perform a second gas-liquid separation on the expanded low-temperature natural gas.

[0018] Further, the residual pressure power generation system for high-pressure natural gas dehydration treatment further includes an air-cooled heat exchanger disposed between the first separator and the expander, and the air-cooled heat exchanger is adapted to rewarm the high-pressure natural gas after the first gas-liquid separation.

[0019] Further, the residual pressure power generation system for high-pressure natural gas dehydration treatment further includes a cooling unit, which includes a lubricating oil station, a lubricating oil pump, a third heat exchanger, a cooling water tower, and a water pump connected in sequence; both the expander and the gearbox are connected to the third heat exchanger, and both the expander and the gearbox are connected to the lubricating oil station; both the third heat exchanger and the cooling water tower are connected to the second heat exchanger; in the third heat exchanger, cooling water exchanges heat with lubricating oil, and the heated cooling water enters the second heat exchanger to reheat the low-temperature natural gas after the first reheating for the second time, and the cooled lubricating oil enters the expander and the gearbox to absorb the heat generated by both of them.

[0020] The technical solution of the present invention has the following advantages:

[0021] The residual pressure power generation method for high-pressure natural gas dehydration treatment provided by the present invention first dehydrates the produced high-pressure natural gas; then, uses the dehydrated high-pressure natural gas to expand and do work to utilize the pressure energy in the high-pressure natural gas; finally, reheats the expanded low-temperature natural gas. After dehydration by this method, the dew point temperature of the natural gas can meet the requirements of the long-distance pipeline, and the pressure energy in the high-pressure natural gas can be effectively utilized. Description of the Drawings

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a schematic flow chart of the residual pressure power generation method for high-pressure natural gas dehydration treatment in the embodiment of the present invention;

[0024] Figure 2 It is a schematic overall structure diagram of the residual pressure power generation system for high-pressure natural gas dehydration treatment in the embodiment of the present invention.

[0025] 1. First control valve; 2. First heat exchanger; 3. First separator;

[0026] 4. Air-cooled heat exchanger; 5. Speed regulating valve group; 6. Expander;

[0027] 7. Gearbox; 8. Generator; 9. Second separator;

[0028] 10. Second control valve; 11. Third control valve; 12. Second heat exchanger;

[0029] 13. Fourth control valve; 14. Fifth control valve; 15. Sixth control valve;

[0030] 16. Seventh control valve; 17. Lubricating oil station; 18. Eighth control valve;

[0031] 19. Lubricating oil pump; 20. Third heat exchanger; 21. Cooling water tower;

[0032] 22. Ninth control valve; 23. Water pump. Detailed implementation manners

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. 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.

[0034] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Figure 2 is the overall structural schematic diagram of the residual pressure power generation system for high-pressure natural gas dehydration treatment in the embodiments of the present invention, as shown in Figure 2As shown in the figure, this embodiment provides a pressure - energy recovery power generation system for high - pressure natural gas dehydration treatment, including: a dehydration unit adapted to dehydrate the produced high - pressure natural gas; an expansion work unit connected to the dehydration unit, adapted to utilize the expanded work of the dehydrated high - pressure natural gas to utilize the pressure energy in the high - pressure natural gas; and a rewarming unit connected to both the dehydration unit and the expansion work unit, adapted to rewarm the expanded low - temperature natural gas.

[0038] For the pressure - energy recovery power generation system for high - pressure natural gas dehydration treatment provided in this embodiment, the dehydration unit first dehydrates the produced high - pressure natural gas; then, the expansion work unit utilizes the expanded work of the dehydrated high - pressure natural gas to utilize the pressure energy in the high - pressure natural gas; finally, the rewarming unit rewarms the expanded low - temperature natural gas. After dehydration by this method, the dew - point temperature of the natural gas can meet the requirements of long - distance pipelines, and the pressure energy in the high - pressure natural gas can be effectively utilized.

[0039] Specifically, the pressure - energy recovery power generation system for high - pressure natural gas dehydration treatment includes a first heat exchanger 2, a second heat exchanger, a third heat exchanger 20, an air - cooled heat exchanger 4, a first separator 3, a second separator 9, an expander 6, a gearbox 7, a generator 8, a lubricating oil station 17, a lubricating oil pump 19, a cooling water tower 21, a water pump 23, a first control valve 11, a second control valve 10, a third control valve 11, a fourth control valve 13, a fifth control valve 14, a sixth control valve 15, a seventh control valve 16, an eighth control valve 18, and a ninth control valve 22.

[0040] Among them, the hot - side inlet of the first heat exchanger 2 is connected to the high - pressure wet - gas inlet system pipeline provided with a first control valve 1, and the hot - side outlet of the first heat exchanger 2 is connected to the inlet of the first separator 3 through a pipeline.

[0041] The gas - phase outlet of the first separator 3 is connected to the inlet of the air - cooled heat exchanger 4 through a pipeline, and the outlet of the air - cooled heat exchanger 4 is connected to the working medium inlet of the expander 6 through a pipeline provided with a speed regulating valve group 5. The liquid - phase outlet of the first separator 3 and the liquid - phase outlet of the second separator 9 are connected through a pipeline provided with a fifth control valve 14 and a pipeline provided with a sixth control valve 15, and after converging into one path, they are connected to the pipeline to the downstream fractionation unit provided with a seventh control valve 16.

[0042] The power shaft of the expander 6 is connected to the gearbox 7 through a coupling, and the gearbox 7 is connected to the generator 8 through a coupling.

[0043] The working - medium outlet of the expander 6 is connected to the inlet of the second separator 9 through a pipeline, and the gas - phase outlet of the second separator 9 is connected to the cold - side inlet of the first heat exchanger 2 through a pipeline provided with a second control valve 10.

[0044] The cold-side outlet of the first heat exchanger 2 is connected to the cold-side inlet of the second heat exchanger 12 through a pipeline provided with a third control valve 11, and the cold-side outlet of the second heat exchanger 12 is connected to the dry gas export pipeline provided with a fourth control valve 13.

[0045] The outlet of the lubricating oil station 17 is connected to the hot-side inlet of the third heat exchanger 20 through a pipeline provided with an eighth control valve 18 and a lubricating oil pump 19. The hot-side outlet of the third heat exchanger 20 is connected to the oil inlets of the expander 6 and the gearbox 7 through pipelines respectively. The oil outlets of the expander 6 and the gearbox 7 are connected to the inlet of the lubricating oil station 17 through pipelines.

[0046] The outlet of the cooling water tower 21 is connected to the cold-side inlet of the third heat exchanger 20 through a pipeline provided with a ninth control valve 22 and a water pump 23. The cold-side outlet of the third heat exchanger 20 is connected to the hot-side inlet of the second heat exchanger 12 through a pipeline, and the hot-side outlet of the second heat exchanger 12 is connected to the inlet of the cooling water tower 21 through a pipeline.

[0047] Among them, the dehydration unit includes a connected first heat exchanger 2 and a first separator 3; the first heat exchanger 2 is adapted to pre-cool and cool down the produced high-pressure natural gas; the first separator 3 is adapted to perform the first gas-liquid separation on the pre-cooled and cooled high-pressure natural gas.

[0048] Among them, the expansion work unit includes a connected expander 6, a gearbox 7 and a generator 8. Both the first separator 3 and the first heat exchanger 2 are connected to the expander 6; the high-pressure natural gas after the first gas-liquid separation and dehydration expands and does work in the expander 6, converting the pressure energy in the high-pressure natural gas into mechanical energy; the mechanical energy is converted into electrical energy in the generator 8.

[0049] Among them, the rewarming unit includes a connected first heat exchanger 2 and a second heat exchanger 12; the first heat exchanger 2 is adapted to perform the first rewarming on the expanded low-temperature natural gas; the second heat exchanger 12 is adapted to perform the second rewarming on the low-temperature natural gas after the first rewarming.

[0050] Among them, the dehydration unit further includes a second separator 9, which is arranged between the expander 6 and the first heat exchanger 2; the second separator 9 is adapted to perform the second gas-liquid separation on the expanded low-temperature natural gas.

[0051] Among them, the pressure energy recovery power generation system for high-pressure natural gas dehydration treatment further includes an air-cooled heat exchanger 4, which is arranged between the first separator 3 and the expander 6, and the air-cooled heat exchanger 4 is adapted to rewarm the high-pressure natural gas after the first gas-liquid separation.

[0052] Among them, the residual pressure power generation system for high-pressure natural gas dehydration treatment further includes a cooling unit, which includes a lubricating oil station 17, a lubricating oil pump 19, a third heat exchanger 20, a cooling water tower 21, and a water pump 23 that are connected; both the expander 6 and the gearbox 7 are connected to the third heat exchanger 20, and both the expander 6 and the gearbox 7 are connected to the lubricating oil station 17; both the third heat exchanger 20 and the cooling water tower 21 are connected to the second heat exchanger 12; in the third heat exchanger 20, cooling water exchanges heat with lubricating oil, and the heated cooling water enters the second heat exchanger 12 to perform a second rewarming on the low-temperature natural gas after the first rewarming, and the cooled lubricating oil enters the expander 6 and the gearbox 7 to absorb the heat generated by the bearings on the coupling connecting the expander 6 and the gearbox 7.

[0053] During use: First, open and adjust the opening degree of the eighth control valve 18 and the frequency of the lubricating oil pump 19 to make the oil supply pressure reach the pressure required for the normal operation of the expander 6 and the gearbox 7.

[0054] Open the seventh control valve 16, the sixth control valve 15, the fifth control valve 14, the third control valve 11, and the second control valve 10; when upstream gas comes in, open the first control valve 1 to make the system operate. The high-pressure wet gas is first precooled by the first heat exchanger 2 to achieve precooling and temperature reduction, and then enters the first separator 3 for the first gas-liquid separation. The separated gas is reheated by the air-cooled heat exchanger 4, and the power of the generator 8 is controlled by adjusting the opening degree of the speed regulating valve group 5, so that the working medium enters the expander 6 to convert the pressure energy into mechanical energy, and then the gearbox 7 drives the generator 8 to convert the mechanical energy into electrical energy. The low-temperature natural gas enters the second separator 9 from the outlet of the expander 6 for the second gas-liquid separation, and the separated gas phase is reheated twice through the first heat exchanger 2 and the second heat exchanger 12 and then exported through the fourth control valve 13; the water and hydrocarbon liquid converge from the liquid phase outlet pipelines of the first separator 3 and the second separator 9 and are transported to the downstream fractionation unit through the seventh control valve 16 to recover hydrocarbons.

[0055] Start the cooling water tower 21, and at the same time adjust the opening degree of the ninth control valve 22 and the frequency of the water pump 23 to make the oil temperature at the hot side outlet of the third heat exchanger 20 reach the temperature range required for the normal operation of the expander 6 and the gearbox 7, and the dry gas at the cold side outlet of the second heat exchanger 12 reach a temperature above the export requirement.

[0056] Figure 1 It is a schematic flow chart of the residual pressure power generation method for high-pressure natural gas dehydration treatment in the embodiment of the present invention. As Figure 1 shown, in another embodiment, a residual pressure power generation method for high-pressure natural gas dehydration treatment is also provided, including the following steps: dehydrating the produced high-pressure natural gas; using the dehydrated high-pressure natural gas to expand and do work to utilize the pressure energy in the high-pressure natural gas; reheating the expanded low-temperature natural gas.

[0057] For the residual pressure power generation method for high-pressure natural gas dehydration treatment, first dehydrate the extracted high-pressure natural gas; then, utilize the expanded high-pressure natural gas to do work and utilize the pressure energy in the high-pressure natural gas; finally, reheat the expanded low-temperature natural gas. After dehydration by this method, the dew point temperature of the natural gas can meet the requirements of the long-distance pipeline, and the pressure energy in the high-pressure natural gas can be effectively utilized.

[0058] Among them, before dehydrating the extracted high-pressure natural gas: first use the expanded low-temperature natural gas to cool the extracted high-pressure natural gas, realize the initial reheating of the expanded low-temperature natural gas, and pre-cool and cool the extracted high-pressure natural gas.

[0059] Among them, conduct the first gas-liquid separation on the pre-cooled and cooled high-pressure natural gas to remove the moisture in the high-pressure natural gas.

[0060] Among them, before utilizing the high-pressure natural gas dehydrated by the first gas-liquid separation to do work, reheat the high-pressure natural gas after the first gas-liquid separation.

[0061] Among them, conduct the second gas-liquid separation on the expanded low-temperature natural gas before the initial reheating of the expanded low-temperature natural gas.

[0062] Among them, when utilizing the high-pressure natural gas dehydrated by the first gas-liquid separation to do work, utilize the heat generated by the work done by the expansion to conduct the second reheating on the low-temperature natural gas after the initial reheating.

[0063] Among them, utilize the high-pressure natural gas dehydrated by the first gas-liquid separation to do work, and utilize the output work of the expansion to generate electricity.

[0064] In summary, for the residual pressure power generation method and system for high-pressure natural gas dehydration treatment in this application, on the one hand, it can control the natural gas dew point to meet the requirements of external transportation, and on the other hand, it drives the generator 8 to generate electricity and feed it into the grid through the gearbox 7.

[0065] For the residual pressure power generation method and system for high-pressure natural gas dehydration treatment in this application, the cold energy carried by the low-temperature natural gas can first pre-cool the high-pressure wet gas through the first heat exchanger 2 to achieve pre-cooling and cooling, and prevent excessive liquid volume at the outlet of the expander 6 from forming blockage.

[0066] For the residual pressure power generation method and system for high-pressure natural gas dehydration treatment in this application, the heat generated by the operation of the expander 6 and the gearbox 7 can be absorbed by the circulating cooling water. While cooling the lubricating oil, the heat absorbed by the cooling water can be used to reheat the low-temperature natural gas, which not only saves the power consumption of the cooling water system fan, etc., but also avoids the fuel consumption of using a water jacket furnace, etc. to reheat the low-temperature natural gas.

[0067] The residual pressure power generation method and system for high-pressure natural gas dehydration treatment in this application can replace the traditional high-pressure natural gas water treatment station process, and while achieving low dew point control of the expander 6, more efficiently recover energy to generate economic benefits.

[0068] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A residual pressure power generation system for high-pressure natural gas dehydration treatment, characterized in that, Comprising: A dehydration unit adapted to dehydrate the produced high-pressure natural gas; An expansion work unit connected to the dehydration unit, adapted to utilize the dehydrated high-pressure natural gas to expand and do work to utilize the pressure energy in the high-pressure natural gas; A rewarming unit connected to both the dehydration unit and the expansion work unit, adapted to rewarm the expanded low-temperature natural gas; The dehydration unit includes a first heat exchanger and a first separator connected to each other; The first heat exchanger is adapted to pre-cool and cool down the produced high-pressure natural gas; The first separator is adapted to perform the first gas-liquid separation on the pre-cooled and cooled high-pressure natural gas; The expansion work unit includes an expander, a gearbox and a generator connected to each other, and the first separator and the first heat exchanger are both connected to the expander; In the expander, the dehydrated high-pressure natural gas expands and does work to convert the pressure energy in the high-pressure natural gas into mechanical energy; In the generator, the mechanical energy is converted into electrical energy; The rewarming unit includes a first heat exchanger and a second heat exchanger connected to each other; The first heat exchanger is adapted to perform primary rewarming on the expanded low-temperature natural gas; The second heat exchanger is adapted to perform secondary rewarming on the low-temperature natural gas after primary rewarming; It further includes a cooling unit, including a lubricating oil station, a lubricating oil pump, a third heat exchanger, a cooling water tower and a water pump connected to each other; the expander and the gearbox are both connected to the third heat exchanger, and the expander and the gearbox are both connected to the lubricating oil station; the third heat exchanger and the cooling water tower are both connected to the second heat exchanger; In the third heat exchanger, the cooling water exchanges heat with the lubricating oil, and the heated cooling water enters the second heat exchanger to perform secondary rewarming on the low-temperature natural gas after primary rewarming, and the cooled lubricating oil enters the expander and the gearbox to absorb the heat generated by both.

2. The residual pressure power generation system for high-pressure natural gas dehydration treatment according to claim 1, wherein The dehydration unit further includes a second separator disposed between the expander and the first heat exchanger; The second separator is adapted to perform secondary gas-liquid separation on the expanded low-temperature natural gas.

3. The residual pressure power generation system for high-pressure natural gas dehydration treatment according to claim 1, wherein It further includes an air-cooled heat exchanger disposed between the first separator and the expander, and the air-cooled heat exchanger is adapted to rewarm the high-pressure natural gas after the first gas-liquid separation.

4. A method for generating electricity by using residual pressure for high-pressure natural gas dehydration treatment, characterized in that, The residual pressure power generation system for high-pressure natural gas dehydration treatment according to any one of claims 1-3 includes the following steps: Dehydrate the produced high-pressure natural gas; Utilize the dehydrated high-pressure natural gas to expand and do work to utilize the pressure energy in the high-pressure natural gas; Rewarm the expanded low-temperature natural gas.

5. The method for high-pressure natural gas dehydration treatment using the residual pressure power generation according to claim 4, wherein Before dehydrating the produced high-pressure natural gas: First, use the expanded low-temperature natural gas to cool down the produced high-pressure natural gas to achieve primary rewarming of the expanded low-temperature natural gas and pre-cool and cool down the produced high-pressure natural gas.

6. The residual pressure power generation method for high-pressure natural gas dehydration treatment according to claim 5, characterized in that The pre-cooled and temperature-reduced high-pressure natural gas is subjected to the first gas-liquid separation to remove the moisture in the high-pressure natural gas.

7. The residual pressure power generation method for high-pressure natural gas dehydration treatment according to claim 6, characterized in that Before the dehydrated high-pressure natural gas expands to do work, the high-pressure natural gas after the first gas-liquid separation is subjected to a rewarming treatment.

8. The residual pressure power generation method for high-pressure natural gas dehydration treatment according to claim 5, characterized in that Before the initially expanded low-temperature natural gas is rewarmed for the first time, the expanded low-temperature natural gas is subjected to a second gas-liquid separation.

9. The residual pressure power generation method for high-pressure natural gas dehydration treatment according to claim 5, characterized in that When the dehydrated high-pressure natural gas expands to do work, the heat generated by the expansion work is used to rewarm the low-temperature natural gas after the first rewarming for the second time.

10. The residual pressure power generation method for high-pressure natural gas dehydration treatment according to any one of claims 4-9, characterized in that The dehydrated high-pressure natural gas is used to expand to do work, and the expanded output work is used for power generation.

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