System and method for utilizing excess pressure of wellhead of non-sulfur-containing well

Abstract

The invention discloses a system and a method for utilizing excess pressure of a wellhead of a non-sulfur-containing well, and relates to the technical field of natural gas. A primary separation device is used for receiving gas from the wellhead and separating the natural gas from the wellhead into a gas phase and a liquid-solid phase; the gas-phase power generation device comprises an expansion machine which is used for receiving a gas phase and generating power to generate electric energy and cold energy; the liquid-solid phase treatment device comprises a liquid-solid separation device and an electrolysis device, and the liquid-solid separation device is used for receiving a liquid-solid phase and separating the liquid-solid phase into liquid and solid; the electrolysis device is used for receiving the separated liquid and carrying out electrolysis hydrogen production through electric energy generated by the expansion machine; and the thermoelectric power generation device is used for receiving cold energy generated by the expansion machine, heat energy carried by a liquid phase and a solid phase in the electrolysis device and heat energy carried by a liquid phase in the liquid-solid separation device, and carrying out thermoelectric power generation. Under the condition that the normal production process of a gas field is not blocked, the non-sulfur-containing wellhead natural gas treatment process can be simplified, wellhead pressure energy is utilized to the maximum degree, and therefore normal production of the gas well is not affected.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas, and particularly to a system and method for utilizing the residual pressure at the wellhead of non-sulfur wells. Background Art

[0002] Domestic natural gas fields are rich in natural gas resources. The pressure energy contained in natural gas during the exploitation process is extremely huge. Reasonably recovering this part of pressure energy will bring huge economic benefits. The wellhead pressure of the vast majority of gas wells ranges from 30 MPa to 100 MPa. The well station ground system uses a multi-stage throttling process to reduce it to between 6.3 MPa and 16 MPa. The pressure energy of about 23 MPa to 90 MPa in the middle is not fully utilized. The existing ways to utilize the residual pressure are mainly expander power generation. During the power generation process, the expansion of natural gas will cause a temperature drop effect, and a large amount of cold energy is generated during this process. The cold energy generally uses methods such as electrically heated tracing, water circuit heating, and adding antifreeze agents to maintain the reasonable treatment and transportation temperature of natural gas. This process increases the consumption of electricity, natural gas, and chemicals.

[0003] At present, the recovery of natural gas pressure energy at home and abroad mainly includes two categories: power generation and refrigeration; using pressure energy for power generation, the generated electricity can enter the urban power grid, or be used for the life and production of the power station itself, or for distributed hydrogen production; in terms of refrigeration, mainly using the expanded low-temperature natural gas for heat exchange in gas power generation, cold storage, chilled water air conditioning, cryogenic refrigeration, and recovering light hydrocarbons, etc.; these are mainly used for the utilization of pressure energy at the back end of the purification pipeline network. At present, the relevant patents and literature are as follows: "A throttling system for generating electricity from the wellhead pressure energy of natural gas" (CN 109162672 A); "An equipment for generating electricity using the wellhead pressure energy of natural gas" (CN 213743551 U); "A system and method for utilizing the wellhead pressure energy of natural gas" (CN113530605A); "A wellhead pressure energy recovery system for natural gas" (CN 215633553 U).

[0004] The above patents all involve the problem of wellhead pressure energy utilization. However, "A throttling system for generating electricity from the wellhead pressure energy of natural gas" is mainly used to save the heat energy consumption for preventing hydrate formation during the expansion of natural gas; "An equipment for generating electricity using the wellhead pressure energy of natural gas" mainly proposes a pressure energy power generation device different from the expander principle; "A system and method for utilizing the wellhead pressure energy of natural gas" is applicable to the situation where the wellhead natural gas is not processed, and realizes the utilization of wellhead pressure energy by converting pneumatic energy into hydraulic energy; "A wellhead pressure energy recovery system for natural gas" mainly does not consider the treatment of wellhead natural gas, directly converts the wellhead pressure energy into electric energy, and uses the electric energy for the system of electrolyzing water to produce hydrogen. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the present invention aims to provide a system and method for utilizing the residual pressure at the wellhead of non-sulfur wells, which can simplify the process of treating natural gas at non-sulfur wellheads without interrupting the normal production process of the gas field, maximize the utilization of the wellhead pressure energy, and thus not affect the normal production of gas wells.

[0006] The present invention is realized through the following technical solutions:

[0007] A system for utilizing the residual pressure at the wellhead of non-sulfur wells includes a first-stage separation device, a gas-phase power generation device, a liquid-solid phase treatment device, and a thermoelectric power generation device that are connected in sequence;

[0008] The first-stage separation device is used to receive the gas from the wellhead and separate the wellhead natural gas into a gas phase and a liquid-solid phase;

[0009] The gas-phase power generation device includes an expander, which is used to receive the gas phase and generate electric energy and cold energy through power generation;

[0010] The liquid-solid phase treatment device includes a liquid-solid separation device and an electrolysis device. The liquid-solid separation device is used to receive the liquid-solid phase and separate the liquid-solid phase into a liquid and a solid; the electrolysis device is used to receive the separated liquid and perform electrolytic hydrogen production through the electric energy generated by the expander. The hydrogen gas produced by the electrolytic hydrogen production is mixed with the natural gas at the outlet of the expander 4 to form hydrogen-doped natural gas;

[0011] The thermoelectric power generation device is used to receive the cold energy generated by the expander, the heat energy carried by the liquid-solid phase itself in the electrolysis device 7, and the heat energy carried by the liquid phase itself in the liquid-solid separation device, and perform thermoelectric power generation.

[0012] Compared with the prior art, the existing method of utilizing residual pressure mainly involves power generation by an expander. During the power generation process, the expansion of natural gas will cause a temperature drop effect, and a large amount of cold energy is generated during this process. Generally, methods such as electric tracing, water circulation heating, and adding antifreeze are used to maintain the reasonable treatment and transportation temperature of natural gas. This process increases problems such as power, natural gas, and chemical consumption. The present invention provides a system for utilizing the residual pressure at the wellhead of non-sulfur wells, which will not affect the normal production of the well station. Secondly, the electric energy and cold energy generated during the utilization of residual pressure can be recovered and utilized to the greatest extent and converted into electric energy. The electric energy can be used for the electricity consumption of in-station equipment and facilities and can also be uploaded to the nearby power grid. It can also recover the water (such as gas field water and fracturing water) during the natural gas production process to the greatest extent for hydrogen production and transport the hydrogen energy to the downstream. Therefore, this system does not consume additional energy and can maximize the utilization of the energy generated during the process from the wellhead to gathering and transportation. In a specific solution, it includes a primary separation device, a gas-phase power generation device, a liquid-solid phase treatment device, and a thermoelectric generation device connected in sequence. The gas coming from the wellhead passes through the primary separation device, and preliminary gas-phase and solid-liquid phase separation is completed within the device. The gas-phase part after passing through the primary separation device passes through a valve with a pressure regulation function to a three-phase separator for fine separation, and the solid-liquid phase part goes to the liquid-solid separation device, that is, the gas field water tank / water pool. The gas-phase part enters the molecular sieve dehydration system, and the dehydrated gas-phase enters the expander for power generation, and the liquid phase enters the electrolysis device, that is, the gas field water tank / water pool. The heat energy of the liquid-solid separation device and the electrolysis device is transmitted to the thermoelectric generator. The temperature difference generated by the cold energy of the expander and the heat energy of the gas field water tank can generate electricity by thermoelectric generation. The electric energy generated by the thermoelectric generator can enter the in-station power grid to supply power for in-station production and life, and can also be used for electrolytic hydrogen production. Therefore, the above solution adds a simple primary separation device at the gas production well station to roughly separate the gas phase and the solid-liquid phase through this device. Secondly, a system for utilizing the residual pressure at the wellhead is established, which can make full use of the electric energy and cold energy converted from the residual pressure at the wellhead, and the electric energy can also be used for electrolytic hydrogen production. The generated hydrogen can be transported to the downstream by being incorporated into the gathering and transportation natural gas pipeline.

[0013] In a further solution, the primary separation device includes a gas transmission pipeline for receiving natural gas from the wellhead. The end of the gas transmission pipeline is provided with an expanded diameter section, and the end of the expanded diameter section is respectively connected with a gas-phase pipeline and a solid-liquid phase pipeline distributed vertically and horizontally. A plurality of flow guiding plates are also provided in the expanded diameter section. The upper end of the flow guiding plate is inclined towards the side of the gas-phase pipeline and is used to guide the gas phase into the gas-phase pipeline. The expanded diameter section facilitates gas-liquid separation.

[0014] In a further solution, a baffle plate is provided in the gas transmission pipeline at the front end of the expanded diameter section. The diameter of the baffle plate is adapted to the inner diameter of the gas transmission pipeline, and a plurality of through holes are provided on the baffle plate. The baffle plate adjusts the air flow into a laminar flow state.

[0015] In a further solution, one end of the solid-liquid phase pipeline away from the diameter-expanding section is arranged to slope downward. The inclined pipeline facilitates the flow into the field water tank / water pool of the liquid-solid separation device.

[0016] In a further solution, the horizontal inclination angle of the solid-liquid phase pipeline is 10° < α < 15°.

[0017] In a further solution, the gas-phase power generation device further includes a three-phase separator and a molecular sieve dehydration system. The three-phase separator is used to receive the gas phase separated by the primary separation device and finely separate the gas phase separated by the primary separation device into a gas phase and a solid-liquid phase; the molecular sieve dehydration system is used to receive the gas phase separated by the three-phase separator and perform dehydration separation into a gas phase and a solid-liquid phase; the expander is used to receive the gas phase separated by the molecular sieve dehydration system; the solid-liquid phase separated by the three-phase separator and the liquid phase separated by the molecular sieve dehydration system both enter the liquid-solid separation device. In this solution, the gas-phase part after the primary separation device passes through a valve with a pressure regulating function to the three-phase separator for fine separation, and the solid-liquid phase part goes to the liquid-solid separation device, that is, the field water tank / water pool; the gas-phase part enters the molecular sieve dehydration system, and the gas phase after dehydration enters the expander for power generation; the wellhead natural gas temperature is T1, the temperature before the three-phase separator is T2, the solid-liquid phase temperature is T2, the temperature after the molecular sieve dehydration is T3, and the temperature after the expander is T4, where T1 > T2 > T3 > T4.

[0018] In a further solution, the front end of the molecular sieve dehydration system is provided with a precooling device for receiving the cold energy generated by the expander, and the precooling device is used to precool the gas phase entering the front end of the dehydration device.

[0019] In a further solution, the liquid-solid separation device separates the liquid-solid phase into liquid and solid by gravity sedimentation.

[0020] In a further solution, the electrolysis device can also perform electrolytic hydrogen production by using the electric energy generated by the thermoelectric power generation device.

[0021] In a further solution, a utilization method of a system for utilizing the residual pressure at the wellhead of a non-sulfur well further includes the following steps:

[0022] S1: The primary separation device separates the received wellhead natural gas into a gas phase and a solid-liquid phase, outputs the gas phase to the gas-phase power generation device, and outputs the solid-liquid phase to the liquid-solid phase treatment device;

[0023] S2: The gas-phase power generation device generates electric energy and cold energy by expanding the received gas phase, outputs the cold energy to the thermoelectric power generation device and the natural gas at the front end of the molecular sieve dehydration system in the gas-phase power generation device respectively, and outputs the electric energy to the electrolysis device;

[0024] The liquid-solid separation device separates the received liquid-solid phase into liquid and solid, and transports the liquid into the electrolysis device. The electrolysis device generates hydrogen through electrolysis by receiving electrical energy from the gas-phase power generation device. The hydrogen generated by electrolysis of water and the natural gas at the outlet of the expander are mixed into hydrogen-doped natural gas and transported to the gathering and transportation pipeline. The thermal energy carried by the liquid-solid phase itself in the electrolysis device and the thermal energy carried by the liquid phase itself in the liquid-solid separation device are transported to the thermoelectric generation device;

[0025] S3: The thermoelectric generation device generates electricity by utilizing the temperature difference between the received cold energy and thermal energy, and outputs the electrical energy to external devices.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] The present invention provides a system for utilizing the residual pressure at the wellhead of non-sulfur wells, which will not affect the normal production of the well station. Secondly, the electrical energy and cold energy generated during the utilization of the residual pressure can be maximally recovered and utilized and converted into electrical energy. The electrical energy can be uploaded to the nearby power grid in addition to being used for the electricity consumption of the station equipment and facilities. It is also possible to maximally recover and produce hydrogen from the water (such as gas field water and fracturing water, etc.) during the natural gas production process, and transport the hydrogen energy to the downstream; Therefore, this system does not consume additional energy and can maximize the utilization of the energy generated during the process from the wellhead to the gathering and transportation production. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts. In the drawings:

[0029] Figure 1 is a schematic flow chart of a system according to an embodiment provided by the present invention;

[0030] Figure 2 is an axial sectional view of a primary separation device according to an embodiment provided by the present invention;

[0031] Figure 3 is an A-A cross-sectional view of a baffle plate according to an embodiment provided by the present invention.

[0032] Markings in the drawings and corresponding component names:

[0033] 1 - primary separation device, 101 - baffle plate, 102 - guide plate, 2 - three-phase separator, 3 - molecular sieve dehydration system, 4 - expander, 5 - thermoelectric generation device, 6 - liquid-solid separation device, 7 - electrolysis device. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments and drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and shall not be construed as limiting the present invention.

[0035] Embodiment:

[0036] This embodiment provides a system for utilizing the residual pressure at the wellhead of a non-sulfur well, as Figures 1 - 3 shown, which includes a first-stage separation device 1, a gas-phase power generation device, a liquid-solid phase treatment device, and a thermoelectric power generation device 5 that are connected in sequence;

[0037] The first-stage separation device 1 is used to receive the gas coming from the wellhead and separate the wellhead natural gas into a gas phase and a liquid-solid phase;

[0038] The gas-phase power generation device includes an expander 4, and the expander 4 is used to receive the gas phase and generate electric energy and cold energy;

[0039] The liquid-solid phase treatment device includes a liquid-solid separation device 6 and an electrolysis device 7. The liquid-solid separation device 6 is used to receive the liquid-solid phase and separate the liquid-solid phase into a liquid and a solid; the electrolysis device 7 is used to receive the separated liquid and perform electrolytic hydrogen production by using the electric energy generated by the expander 4. The hydrogen gas produced by the electrolytic hydrogen production and the natural gas at the outlet of the expander 4 are mixed into hydrogen-doped natural gas;

[0040] The thermoelectric power generation device 5 is used to receive the cold energy generated by the expander 4, the thermal energy carried by the liquid-solid phase itself in the electrolysis device 7, and the thermal energy carried by the liquid phase itself in the liquid-solid separation device 6, and perform thermoelectric power generation.

[0041] In the prior art, the existing method of utilizing residual pressure mainly involves using an expander 4 to generate electricity. During the power generation process, the expansion of natural gas will cause a cooling effect, and a large amount of cold energy is generated during this process. Generally, methods such as electric tracing, water circuit heating, and adding antifreeze are used to maintain the reasonable treatment and transportation temperature of natural gas. This process increases problems such as power, natural gas, and chemical consumption. The present invention provides a system for utilizing the residual pressure at the wellhead of non-sulfur wells, which will not affect the normal production of the well station. Secondly, the electric energy and cold energy generated during the utilization of residual pressure can be recovered and utilized to the greatest extent and converted into electric energy. The electric energy can be used for the electricity consumption of in-station equipment and facilities and can also be uploaded to the nearby power grid. It can also recover the water (such as gas field water and fracturing water) generated during the natural gas extraction process to the greatest extent for hydrogen production and transport the hydrogen energy to the downstream. Therefore, this system does not consume additional energy and can maximize the utilization of the energy generated during the process from the wellhead to the gathering and transportation. In a specific embodiment, it includes a primary separation device 1, a gas-phase power generation device, a liquid-solid phase treatment device, and a thermoelectric power generation device 5 connected in sequence. The gas coming from the wellhead passes through the primary separation device 1, and preliminary gas-phase and solid-liquid phase separation is completed within the device. The gas-phase part after passing through the primary separation device 1 passes through a valve with a pressure regulation function to a three-phase separator 2 for fine separation, and the solid-liquid phase part goes to a liquid-solid separation device 6, that is, a gas field water tank / water pool. The gas-phase part enters a molecular sieve dehydration system, and the dehydrated gas-phase enters the expander 4 for power generation. The liquid phase enters an electrolysis device 7, that is, a gas field water tank / water pool. The heat energy of the liquid-solid separation device 6 and the electrolysis device 7 is transmitted to the thermoelectric generator. The temperature difference generated by the cold energy of the expander 4 and the heat energy of the gas field water tank can be used for thermoelectric power generation. The electric energy generated by the thermoelectric generator can enter the in-station power grid to supply power for in-station production and life, or can be used for electrolytic hydrogen production. Therefore, in the above solution, a simple primary separation device 1 is added to the gas production well station. Through this device, the gas phase and the solid-liquid phase are roughly separated. Secondly, a system for utilizing the residual pressure at the wellhead is established, which can make full use of the electric energy and cold energy converted from the residual pressure at the wellhead, and the electric energy can also be used for electrolytic hydrogen production. The generated hydrogen can be transported to the downstream through the gathering and transportation natural gas pipeline after being mixed in.

[0042] In this embodiment, the primary separation device 1 includes a gas transmission pipeline for receiving natural gas from the wellhead. The end of the gas transmission pipeline is provided with an expanded diameter section, and the end of the expanded diameter section is respectively connected with a gas-phase pipeline and a solid-liquid phase pipeline distributed vertically and horizontally. A plurality of flow guiding plates 102 are also provided in the expanded diameter section. The upper end of the flow guiding plate 102 is inclined towards the side of the gas-phase pipeline and is used for guiding the gas phase into the gas-phase pipeline. The expanded diameter section facilitates gas-liquid separation.

[0043] In this embodiment, a baffle plate 101 is provided in the gas transmission pipeline at the front end of the expanded diameter section. The diameter of the baffle plate 101 is adapted to the inner diameter of the gas transmission pipeline, and a plurality of through holes are provided on the baffle plate 101. The baffle plate 101 adjusts the air flow to a laminar flow state.

[0044] In this embodiment, one end of the solid-liquid phase pipeline far from the diameter-expanded section is arranged to incline downward. The inclined pipeline facilitates the flow into the field water tank / water pool of the liquid-solid separation device 6.

[0045] In this embodiment, the horizontal inclination angle of the solid-liquid phase pipeline is 10° < α < 15°.

[0046] In this embodiment, the gas-phase power generation device further includes a three-phase separator 2 and a molecular sieve dehydration system 3. The three-phase separator 2 is used to receive the gas phase separated by the primary separation device 1 and finely separate the gas phase separated by the primary separation device 1 into a gas phase and a solid-liquid phase; the molecular sieve dehydration system 3 is used to receive the gas phase separated by the three-phase separator 2 and perform dehydration separation into a gas phase and a solid-liquid phase; the expander 4 is used to receive the gas phase separated by the molecular sieve dehydration system 3; the solid-liquid phase separated by the three-phase separator 2 and the liquid phase separated after the molecular sieve dehydration system 3 both enter the liquid-solid separation device 6. In this solution, the gas-phase part after the primary separation device 1 passes through a valve with a pressure regulation function to the three-phase separator 2 for fine separation, and the solid-liquid phase part goes to the liquid-solid separation device 6, that is, the field water tank / water pool; the gas-phase part enters the molecular sieve dehydration system, and the gas phase after dehydration enters the expander 4 for power generation; the wellhead natural gas temperature T1, the temperature T2 before the three-phase separator 2, the solid-liquid phase temperature T2, the temperature T3 after the molecular sieve dehydration, and the temperature T4 after the expander 4, where T1 > T2 > T3 > T4.

[0047] In this embodiment, the front end of the molecular sieve dehydration system 3 is provided with a precooling device for receiving the cold energy generated by the expander 4, and the precooling device is used to precool the gas phase entering the front end of the dehydration device.

[0048] In this embodiment, the liquid-solid separation device 6 separates the liquid-solid phase into liquid and solid by gravity sedimentation.

[0049] In this embodiment, the electrolysis device 7 can also perform electrolytic hydrogen production by using the electric energy generated by the thermoelectric power generation device 5.

[0050] It also includes the following specific working principles:

[0051] The method for utilizing the wellhead residual pressure resources includes gas, liquid-solid primary separation, a gas-phase treatment power generation system, a thermoelectric power generation system, a liquid-solid phase treatment and storage system, and an energy exchange system; finally, dehydrated natural gas or hydrogen-doped natural gas is transported downstream.

[0052] Gas, liquid-solid primary separation: The wellhead gas passes through the primary separation device 1, and preliminary gas-phase and solid-liquid phase separation is completed in the device; in the rough separation device ( Figure 2)After the gas from the wellhead enters the pipeline, a baffle 101 is set to adjust the gas flow into a laminar state; after the gas from the wellhead passes through the enlarged pipe diameter, the gas phase part enters the gas pipeline through the upper guide plate 102 of the separation device, and the solid-liquid phase flows through the solid-liquid pipeline with a certain inclination angle (10° < α < 15°) connected to the lower part of the separation device to the gas field water tank / pool in the liquid-solid separation device 6.

[0053] Gas phase treatment power generation system: The gas phase part after passing through the first-stage separation device 1 passes through a valve with a pressure regulating function to the three-phase separator 2 for fine separation, and the solid-liquid phase part goes to the gas field water tank / pool in the liquid-solid separation device 6; the gas phase part enters the molecular sieve dehydration system 3, and after dehydration, the gas phase enters the expander 4 for power generation, and the liquid phase enters the gas field water tank / pool in the liquid-solid separation device 6.

[0054] Liquid-solid phase storage hydrogen production system: The solid-liquid phase passing through the first-stage separation device 1 enters the gas field water tank / pool in the liquid-solid separation device 6 for gravity sedimentation to separate the solid-liquid phase, and then the liquid phase enters the gas field water tank / pool in the electrolysis device 7, and the electric energy generated by the expander 4 or the thermoelectric power generation is used to electrolyze water to produce hydrogen.

[0055] Thermoelectric power generation system: The heat energy of the liquid-solid separation device 6 and the electrolysis device 7 is transmitted to the thermoelectric generator, and the temperature difference generated by the cold energy of the expander 4 and the heat energy of the gas field water tank can be used for thermoelectric power generation.

[0056] Energy exchange system: The cold energy generated by the expander 4 can be input to the front end of the molecular sieve dehydration system 3 to pre-cool the natural gas, thereby improving the dehydration effect. The electric energy generated by the expander 4 can enter the electrolysis device 7 to electrolyze water to produce hydrogen. The hydrogen produced by electrolyzing water and the natural gas at the outlet of the expander 4 are mixed into hydrogen-doped natural gas and transported through the gathering and transportation pipeline to the downstream. The electric energy generated by the thermoelectric generator can enter the station power grid to supply power for the production and life in the station, or can also be used for electrolyzing water to produce hydrogen.

[0057] The present invention relates to a system and method for utilizing the residual pressure at the wellhead of a non-sulfur well. First, a simple first-stage separation device 1 is added at the gas production well station to roughly separate the gas phase and the solid-liquid phase through this device; secondly, a system for utilizing the residual pressure at the wellhead is established, which can make full use of the electric energy and cold energy converted from the residual pressure at the wellhead, and the electric energy can also be used for electrolyzing water to produce hydrogen, and the produced hydrogen can be transported to the downstream through the gathering and transportation natural gas pipeline.

[0058] The present invention will not affect the normal production of the well station first. Secondly, the electric energy and cold energy generated during the utilization of the residual pressure can be recovered and utilized to the greatest extent and converted into electric energy. The electric energy can be uploaded to the nearby power grid in addition to being used for the electricity consumption of the equipment and facilities in the station, and the water (such as gas field water and fracturing water) in the process of natural gas production can also be recovered to produce hydrogen to the greatest extent, and the hydrogen energy is transported to the downstream. Therefore, this system does not consume additional energy and can maximize the utilization of the energy generated during the process from the wellhead to the gathering and transportation production.

[0059] The specific embodiments described above further elaborate on the object, technical solution and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for utilizing the residual pressure at the wellhead of a non-sulfur well, characterized in that, it includes a first-stage separation device (1), a gas-phase power generation device, a liquid-solid phase treatment device, and a thermoelectric power generation device (5) connected in sequence; The first-stage separation device (1) is used to receive the gas coming from the wellhead and separate the wellhead natural gas into a gas phase and a liquid-solid phase; The gas-phase power generation device includes an expander (4), and the expander (4) is used to receive the gas phase and generate electric energy and cold energy; The liquid-solid phase treatment device includes a liquid-solid separation device (6) and an electrolysis device (7). The liquid-solid separation device (6) is used to receive the liquid-solid phase and separate the liquid-solid phase into a liquid and a solid; the electrolysis device (7) is used to receive the separated liquid and perform electrolysis to produce hydrogen by using the electric energy generated by the expander (4). The hydrogen produced by the electrolysis of hydrogen and the natural gas at the outlet of the expander (4) are mixed into hydrogen-doped natural gas; The thermoelectric power generation device (5) is used to receive the cold energy generated by the expander (4), the heat energy carried by the liquid-solid phase itself in the electrolysis device (7), and the heat energy carried by the liquid phase itself in the liquid-solid separation device (6), and perform thermoelectric power generation.

2. The system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 1, characterized in that, The first-stage separation device (1) includes a gas transmission pipeline for receiving the wellhead natural gas. The end of the gas transmission pipeline is provided with an enlarged diameter section. The end of the enlarged diameter section is respectively connected with a gas pipeline and a solid-liquid phase pipeline distributed up and down; a plurality of flow guiding plates (102) are also arranged in the enlarged diameter section. The upper end of the flow guiding plate (102) is inclined towards the side of the gas pipeline and is used to guide the gas into the gas pipeline.

3. The system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 2, characterized in that, A baffle plate (101) is arranged in the gas transmission pipeline at the front end of the enlarged diameter section. The diameter of the baffle plate (101) is adapted to the inner diameter size of the gas transmission pipeline, and a plurality of through holes are arranged on the baffle plate (101).

4. The system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 2, characterized in that, The end of the solid-liquid phase pipeline away from the enlarged diameter section is inclined downward.

5. The system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 4, characterized in that, The horizontal inclination angle of the solid-liquid phase pipeline is 10° < α < 15°.

6. The system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 1, characterized in that, The gas-phase power generation device further includes a three-phase separator (2) and a molecular sieve dehydration system (3). The three-phase separator (2) is used to receive the gas phase separated by the first-stage separation device (1) and finely separate the gas phase separated by the first-stage separation device (1) into a gas phase and a solid-liquid phase; the molecular sieve dehydration system (3) is used to receive the gas phase separated by the three-phase separator (2) and perform dehydration separation into a gas phase and a solid-liquid phase; The expander (4) is used to receive the gas phase separated by the molecular sieve dehydration system (3); The solid-liquid phase separated by the three-phase separator (2) and the liquid phase separated by the molecular sieve dehydration system (3) both enter the liquid-solid separation device (6).

7. A system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 6, wherein, a pre-cooling device for receiving the cold energy generated by the expander (4) is provided at the front end of the molecular sieve dehydration system (3), and the pre-cooling device is used to pre-cool the gas phase entering the front end of the molecular sieve dehydration system (3).

8. A system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 1, wherein, the liquid-solid separation device (6) separates the liquid-solid phase into liquid and solid by gravity sedimentation.

9. A system for utilizing the residual pressure at the wellhead of a non-sulfur well according to claim 1, wherein, the electrolysis device (7) can also perform electrolytic hydrogen production by using the electric energy generated by the thermoelectric power generation device (5).

10. A utilization method of a system for utilizing the residual pressure at the wellhead of a non-sulfur well according to any one of claims 1 to 9, wherein, it further includes the following steps: S1: The primary separation device (1) separates the received wellhead natural gas into a gas phase and a liquid-solid phase, outputs the gas phase to the gas-phase power generation device, and outputs the liquid-solid phase to the liquid-solid phase treatment device; S2: The gas-phase power generation device generates electric energy and cold energy by expanding the received gas phase, outputs the cold energy to the front end of the molecular sieve dehydration system (3) in the gas-phase power generation device and the natural gas in the thermoelectric power generation device (5) respectively, and outputs the electric energy to the electrolysis device (7); The liquid-solid separation device (6) separates the received liquid-solid phase into liquid and solid, transports the liquid into the electrolysis device (7), the electrolysis device (7) performs electrolytic hydrogen production by receiving the electric energy of the gas-phase power generation device, the hydrogen generated by the electrolytic hydrogen production and the natural gas at the outlet of the expander (4) are mixed into hydrogen-doped natural gas and transported to the gathering pipeline, and the heat energy carried by the liquid-solid phase itself in the electrolysis device (7) and the heat energy carried by the liquid phase itself in the liquid-solid separation device (6) are transported to the thermoelectric power generation device (5); S3: The thermoelectric power generation device (5) performs thermoelectric power generation by using the received cold energy and heat energy, and outputs the electric energy to external equipment.

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