A nitrogen generation system and method for high temperature water deficient oil fields

Abstract

The application discloses a nitrogen production system and method for high-temperature water-deficient environment oil fields, and relates to the technical field of oil and gas field development. The application comprises an air compressor, an oil remover, a cooler, a filter, a cold dryer, a separator, an instrument air storage tank and a PSA nitrogen production system, and a bypass pipeline is arranged between the filter and the cold dryer, a composite air cooler and a separator are arranged on the bypass pipeline, and an automatic temperature adjusting structure is formed by cooperating with valves V1 and V2, a temperature sensor and a PLC controller. When the temperature of compressed air is higher than 40 DEG C, the system is started to perform air cooling and temperature reduction through the bypass pipeline; when the temperature is lower than a threshold value, the bypass pipeline is closed to directly pass the cold dryer. A rotating contact cold disc, a ceramic ring, an arc-shaped flow guide strip and a hollow blade are arranged in the cold dryer to form a spiral flow path, so that the contact area of gas and a cold surface is increased. An automatic liquid discharge mechanism and a liquid level sensor are arranged to improve the gas-liquid separation efficiency.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, specifically to a nitrogen production system and method for oil fields in high-temperature and water-scarce environments. Background Technology

[0002] In oil and gas field development, nitrogen injection is one of the key technologies for enhancing oil recovery. This technology injects high-purity nitrogen into the oil reservoir to maintain pressure and displace crude oil. Currently, on-site nitrogen production commonly employs pressure swing adsorption (PSA) or membrane separation technologies, the core of which is to separate nitrogen by adsorbing impurities such as oxygen and water vapor from the air using molecular sieves.

[0003] However, the adsorption capacity and efficiency of molecular sieves are highly dependent on the temperature of the compressed air entering the nitrogen generator. Excessively high temperatures significantly reduce the adsorption capacity of the molecular sieve, leading to a decrease in the purity of the produced nitrogen. Traditional water cooling methods are unusable due to water scarcity, while conventional air coolers struggle to cool compressed air to the ideal temperature (typically required to be no higher than ambient temperature +10°C) in extreme high-temperature environments (ambient temperatures often exceed 40°C). This results in excessively high air temperatures entering the nitrogen generator, ultimately making it difficult to consistently achieve the industry requirement of nitrogen purity above 99.5%. Insufficient nitrogen purity introduces more oxygen and moisture, exacerbating the corrosion risk of downhole tubing and equipment, and ultimately affecting oil recovery efficiency.

[0004] Therefore, there is an urgent need in this field for an oilfield nitrogen injection system and method that can adapt to high-temperature and water-scarce environments, effectively control the intake temperature, and thus stably produce high-purity nitrogen. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides the following technical solution: a nitrogen generation system for oilfields in high-temperature and water-scarce environments, comprising an air compressor, an oil separator, a cooler, a filter, a refrigerated dryer, a second separator, an instrument air storage tank, and a PSA nitrogen generation system connected sequentially along an air flow path; it also includes a bypass pipeline disposed between the filter and the refrigerated dryer, the bypass pipeline being provided with an air cooler and a separator, and control valves V1 and V2; and a temperature sensor and a controller are also provided for controlling the opening and closing states of valves V1 and V2 according to the compressed air temperature.

[0006] Preferably, the air cooler is a composite air cooler, which adopts a plate-fin type or a heat transfer structure with an eddy current generator; the controller is a PLC, which can receive temperature sensor signals and automatically control the opening and closing of valves V1 and V2 to stabilize the gas temperature at 20~40℃, thereby ensuring that the nitrogen purity is not less than 99.5%.

[0007] The refrigerated dryer includes a refrigerated drying shell. Multiple embedded rotating slots are formed along the axial direction of the circumferential surface of the inner wall of the shell. A ceramic ring is rotatably installed in each slot, and a hollow contact cooling plate is fixedly installed within each ceramic ring. A circular cavity is fixedly installed at the axial center of the contact cooling plate. The circular cavity is divided into two independent spaces, which are connected to the contact cooling plate via refrigerant flow windows on the circular cavity. Multiple concentrically fitted arc-shaped guide strips are symmetrically fixedly installed on both sides of the inner wall of the contact cooling plate. Each arc-shaped guide strip on the same side has a different diameter, and a gap is left between adjacent arc-shaped guide strips. The annular cavity is equipped with a channel aligned with the refrigerant flow window. A central connecting pipe is fixedly connected to the inner side of the annular cavity via four hollow blades. The interior of the central connecting pipe is divided into two independent spaces by a second partition plate. The two independent spaces within the central connecting pipe are connected to the corresponding independent spaces within the annular cavity via three hollow blades. All central connecting pipes are connected in series and coaxially aligned (i.e., the second partition plate is aligned, allowing the two independent spaces within the central connecting pipe to be connected). The axial length of the central connecting pipe is greater than the axial length of the contact cold plate, leaving a gap between adjacent contact cold plates (different gap sizes are selected based on the gas viscosity, generally one to one and a half millimeters).

[0008] Preferably, the refrigerated drying shell is provided with an air inlet and a drain outlet, wherein a water collection pool communicating with the interior of the refrigerated drying shell is fixedly installed at the drain outlet, a drain outlet is fixedly provided at the bottom of the water collection pool, and an electric valve is provided inside the drain outlet.

[0009] Preferably, a flow guide is fixedly and sealed outside the air inlet of the refrigerated drying shell. The flow guide is coaxially arranged with the refrigerated drying shell, and an air inlet pipe is fixedly connected to the side axis of the flow guide. An impeller is rotatably installed inside the air inlet pipe, and an impeller shaft is fixedly installed at the axis of the impeller. A gap is left between the inner wall of the flow guide facing the air inlet pipe and the side of the refrigerated drying shell. A gear ring shell is fitted in this gap and is fixed to the refrigerated drying shell. A gear ring is rotatably installed inside the gear ring shell, and a central gear is rotatably engaged at the center of the inner side of the gear ring. The central gear and the gear ring are driven by three planetary gears meshing. All planetary gears are rotatably mounted on a planetary gear support plate, and the planetary gear support plate is fixed to the gear ring shell by a planetary gear support plate fixing block. A sealing cover is also fixedly and sealed on the gear ring shell. The impeller shaft passes through the sealing cover and the planetary gear support plate and is fixedly engaged with the central gear. The planetary gear support plate fixing block is fixed to the gear ring housing by screws, which can drive the planetary gear support plate fixing block to move radially along the gear ring housing, and restrict the planetary gear support plate by squeezing friction, so that the planetary gear support plate is fixed on the gear ring housing.

[0010] Preferably, the toothed ring is coaxially fixed to one of the central shaft connecting pipes at one end via a shaft rod, which also serves to seal one end of the central shaft connecting pipe; a shaft tube is coaxially fixedly connected to one of the central shaft connecting pipes at the other end, and the shaft tube is divided into two independent spaces by a first partition plate. The two independent spaces in the shaft tube are connected to the two independent spaces in the central shaft connecting pipe, and the first partition plate is aligned with the second partition plate; a pipe opening is provided at the axial center position on the side of the refrigerated drying shell away from the impeller shaft, and an exhaust pipe is fixedly connected to the pipe opening, wherein the shaft tube rotary seal extends to the outside of the exhaust pipe, and a refrigerant inlet and a refrigerant outlet are provided at the position of the shaft tube on the outside of the exhaust pipe, and the refrigerant inlet and refrigerant outlet are respectively connected to the two independent spaces in the shaft tube; two rotary connecting heads are fixedly installed on the exhaust pipe, and both rotary connecting heads are fitted with the shaft tube rotary seal, and the two rotary connecting heads are respectively connected to the refrigerant inlet and the refrigerant outlet.

[0011] A method for controlling the purity of nitrogen in a nitrogen production system for oilfields in high-temperature and water-scarce environments includes the following steps: Step 1: After being compressed by an air compressor, air undergoes preliminary treatment by passing through an oil separator, cooler, and filter, and its temperature is detected; Step 2: If the temperature exceeds a set threshold, valves V1 and V2 are opened, allowing the gas to be cooled and separated by an air cooler and separator before entering a refrigerated dryer; Step 3: If the temperature is below the set threshold, valves V1 and V2 are closed, allowing the gas to directly enter the refrigerated dryer; Step 4: After being processed by the refrigerated dryer, the gas passes through a second separator and enters the instrument air storage tank, ultimately entering the PSA nitrogen production system to produce nitrogen.

[0012] Preferably, the threshold temperature in steps 2 and 3 is set to 40°C; by controlling the opening and closing of valves V1 and V2, the temperature of the gas entering the PSA nitrogen generation system is maintained between 20°C and 40°C. The entire system relies entirely on air cooling in water-scarce environments, requiring no water resources. This method reduces the corrosion risk of downhole tubing and equipment, saving on annual equipment maintenance costs. This method can effectively improve oil and gas recovery rates, increasing sales revenue. Increased nitrogen purity also saves costs annually.

[0013] Compared with the prior art, the present invention has the following advantages: (1) The present invention achieves intelligent switching of cooling path through bypass design and temperature control valve linkage, which can not only ensure the cooling effect under high temperature conditions, but also save energy under low temperature conditions; (2) The present invention adopts air cooling method, which is suitable for water-scarce environment and solves the problem that traditional water cooling cannot be applied; (3) The present invention has a reasonable system structure, is easy to operate, and can greatly improve nitrogen purity and nitrogen production efficiency; (4) The present invention effectively reduces the corrosion risk of downhole tubing and equipment, extends equipment life, and improves crude oil recovery rate. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention.

[0015] Figure 2 This is a schematic diagram of the isometric view of the refrigerated dryer of the present invention.

[0016] Figure 3 This is an isometric view of the refrigerated dryer of the present invention from another perspective.

[0017] Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle.

[0018] Figure 5 This is a schematic diagram of the air guide structure of the present invention.

[0019] Figure 6 This is a structural diagram of the cold drying shell of the present invention.

[0020] Figure 7 This is a structural diagram of the shaft tube of the present invention.

[0021] Figure 8 This is a diagram showing the installation position of the contact cold plate of the present invention inside the refrigerated drying housing.

[0022] Figure 9 This is a structural diagram of the embedded rotating groove of the present invention.

[0023] Figure 10 This is a structural diagram of the contact cold plate of the present invention.

[0024] Figure 11 This is a diagram of the internal structure of the contact cold plate of the present invention.

[0025] Figure 12 For the present invention Figure 11 Enlarged view of section B in the middle.

[0026] In the diagram: 1-Air compressor; 2-Oil separator; 3-Cooler; 4-Filter; 5-Air cooler; 6-Separator; 7-Refrigerated dryer; 701-Refrigerated dryer housing; 702-Flow guide shroud; 703-Inlet pipe; 704-Impeller; 705-Impeller shaft; 706-Exhaust pipe; 707-Pipe inlet; 708-Water sump; 709-Drain outlet; 710-Inlet opening; 711-Drain opening; 712-Shaft tube; 713-Refrigerant inlet; 714-Refrigerant outlet; 715-Rotating connector; 716-Sealing cover. 717-Gear ring housing; 718-Planetary gear support plate; 719-Planetary gear support plate fixing block; 720-Gear ring; 721-Planetary gear; 722-Central gear; 723-First partition plate; 724-Embedded rotating groove; 725-Contact cold plate; 726-Ceramic ring; 727-Hollow blade; 728-Arc-shaped guide strip; 729-Refrigerant flow window; 730-Second partition plate; 731-Annular cavity; 732-Central shaft connecting pipe; 8-Second separator; 9-Instrument air storage tank; 10-PSA nitrogen generation system. Detailed Implementation

[0027] The following is in conjunction with the appendix Figures 1-12 The technical solution of the present invention will be further illustrated through specific embodiments.

[0028] This invention provides a nitrogen generation system for oilfields in high-temperature and water-scarce environments. The system comprises an air compressor 1, an oil separator 2, a cooler 3, a filter 4, a refrigerated dryer 7, a second separator 8, an instrument air storage tank 9, and a PSA nitrogen generation system 10, connected sequentially along an air flow path. It also includes a bypass pipeline located between the filter 4 and the refrigerated dryer 7, on which an air cooler 5 and a separator 6 are installed, along with control valves V1 and V2. A temperature sensor and a controller are also provided to control the opening and closing of valves V1 and V2 based on the compressed air temperature. The air cooler 5 is a composite air cooler, employing a plate-fin type or a heat transfer structure with an eddy current generator. The controller is a PLC capable of receiving temperature sensor signals and automatically controlling the opening and closing of valves V1 and V2 to stabilize the gas temperature at 20~40℃, thereby ensuring a nitrogen purity of not less than 99.5%.

[0029] A method for controlling the purity of nitrogen in a nitrogen production system for oilfields in high-temperature and water-scarce environments includes the following steps: Step 1: After being compressed by an air compressor 1, air is pre-treated by passing through an oil separator 2, a cooler 3, and a filter 4, and its temperature is detected; Step 2: If the temperature exceeds a set threshold, valves V1 and V2 are opened, allowing the gas to be cooled and separated by an air cooler 5 and a separator 6 before entering a refrigerated dryer 7; Step 3: If the temperature is below the set threshold, valves V1 and V2 are closed, allowing the gas to directly enter the refrigerated dryer 7; Step 4: After being treated by the refrigerated dryer 7, the gas passes through a second separator 8 and enters an instrument air storage tank 9, and finally enters a PSA nitrogen production system 10 to produce nitrogen.

[0030] In steps 2 and 3, the threshold temperature is set to 40°C; by controlling the opening and closing of valves V1 and V2, the temperature of the gas entering the PSA nitrogen generation system 10 is maintained at 20~40°C.

[0031] During system operation, ambient temperature air is compressed by air compressor 1 and then undergoes preliminary treatment via oil separator 2, cooler 3, and filter 4. A temperature sensor monitors the compressed air temperature in real time and transmits the signal to the PLC controller. If the temperature exceeds 40℃, the controller opens valves V1 and V2, allowing the compressed air to be cooled by air cooler 5 and separated by gas-liquid separator 6 before entering the refrigerated dryer 7. If the temperature is below 40℃, valves V1 and V2 are closed, and the compressed air directly enters the refrigerated dryer 7. The subsequent gas is buffered by a second separator 8 and instrument air storage tank 9 before entering the PSA nitrogen generation system 10, producing high-purity nitrogen which is then injected into the oil well. The entire system relies entirely on air cooling in water-scarce environments, requiring no water resources. This method reduces the risk of corrosion to downhole tubing and equipment, saving annual equipment maintenance costs. It effectively improves oil and gas recovery rates, increasing sales revenue. The increased nitrogen purity also saves costs annually.

[0032] The refrigerated dryer 7 includes a refrigerated drying shell 701. Multiple embedded rotating slots 724 are formed along the axial direction of the circumferential surface of the inner wall of the refrigerated drying shell 701. A ceramic ring 726 is rotatably installed in each embedded rotating slot 724. A hollow contact cooling plate 725 is fixedly installed in each ceramic ring 726. An annular cavity 731 is fixedly installed at the axial center of the contact cooling plate 725. The annular cavity 731 is divided into two independent spaces, which are connected to the interior of the contact cooling plate 725 through refrigerant flow windows 729 formed on the annular cavity 731. Multiple concentrically fitted arc-shaped guide strips 728 are symmetrically fixedly installed on both sides of the inner wall of the contact cooling plate 725. The diameter of each arc-shaped guide strip 728 on the same side is different, and a gap is left between adjacent arc-shaped guide strips 728. The flow strips 728 are provided with channels aligned with the refrigerant flow window 729; the inner side of the annular cavity 731 is fixedly connected to the central shaft connecting pipe 732 by four hollow blades 727. The interior of the central shaft connecting pipe 732 is divided into two independent spaces by the second partition plate 730. The two independent spaces in the central shaft connecting pipe 732 are connected to the corresponding independent spaces in the annular cavity 731 by three hollow blades 727; all the central shaft connecting pipes 732 are connected in series and coaxially aligned, that is, the second partition plate 730 is aligned, so that the two independent spaces in the central shaft connecting pipe 732 are connected through each other. The axial length of the central shaft connecting pipe 732 is greater than the axial length of the contact cold plate 725, so that there is a gap between two adjacent contact cold plates 725 (different gap sizes are selected according to the viscosity of the gas, generally one to one and a half millimeters). The refrigerated drying housing 701 has an air inlet 710 and a drain opening 711. A water collection tank 708 communicating with the interior of the refrigerated drying housing 701 is fixedly installed at the drain opening 711. A drain outlet 709 is fixedly installed at the bottom of the water collection tank 708, and an electric valve is installed inside the drain outlet 709.A flow guide 702 is fixedly and sealed outside the air inlet 710 on the refrigerated drying housing 701. The flow guide 702 is coaxially arranged with the refrigerated drying housing 701. An air inlet pipe 703 is fixedly connected to the side axis of the flow guide 702. An impeller 704 is rotatably installed inside the air inlet pipe 703, and an impeller shaft 705 is fixedly installed at the axis of the impeller 704. A gap is left between the inner wall of the flow guide 702 facing the air inlet pipe 703 and the side of the refrigerated drying housing 701. A toothed ring housing 717 is fitted in this gap and is fixed to the refrigerated drying housing 701. An internally rotating gear ring 720 is mounted, with a central gear 722 rotatably engaged at the center of its inner side. The central gear 722 and gear ring 720 are driven by three meshing planetary gears 721. All planetary gears 721 are rotatably mounted on a planetary gear support plate 718, which is fixed to the gear ring housing 717 by a planetary gear support plate fixing block 719. A sealing cover plate 716 is also fixedly and sealed on the gear ring housing 717. An impeller shaft 705 passes through the sealing cover plate 716 and the planetary gear support plate 718, and is fixedly engaged with the central gear 722. The planetary gear support plate fixing block 719 is fixedly engaged with the gear ring housing 717 by screws, enabling the fixing block 719 to move radially along the gear ring housing 717. The planetary gear support plate 718 is restrained by compression friction, thus fixing it to the gear ring housing 717. The gear ring 720 is coaxially fixed to one of the central shaft connecting pipes 732 via a shaft rod, which also serves to seal one end of the central shaft connecting pipe 732. A shaft tube 712 is coaxially fixedly connected to the other end of the central shaft connecting pipe 732. The shaft tube 712 is divided into two independent spaces by a first partition plate 723. These two independent spaces communicate with the two independent spaces within the central shaft connecting pipe 732, and the first partition plate 723 is aligned with the second partition plate 730. A pipe opening 707 is located at the axial center of the refrigerated drying housing 701 on the side furthest from the impeller shaft 705. An exhaust pipe 706 is fixedly connected to the 7, wherein the shaft tube 712 rotates and seals through to the outside of the exhaust pipe 706. The shaft tube 712 is provided with a refrigerant inlet 713 and a refrigerant outlet 714 at the position outside the exhaust pipe 706. The refrigerant inlet 713 and the refrigerant outlet 714 are respectively connected to two independent spaces inside the shaft tube 712. Two rotating connectors 715 are fixedly installed on the exhaust pipe 706. Both rotating connectors 715 are rotated and seal with the shaft tube 712. The two rotating connectors 715 are respectively connected to the refrigerant inlet 713 and the refrigerant outlet 714.

[0033] Gas is input through the intake pipe 703, which drives the impeller 704 to rotate. The impeller 704 drives the impeller shaft 705 to rotate, which in turn drives the central gear 722 to rotate. The central gear 722 drives the gear ring 720 to rotate via the planetary gear 721. The gear ring 720 drives the internal central shaft connecting pipe 732 to rotate. Since all the central shaft connecting pipes 732 are fixed together, all the central shaft connecting pipes 732, as well as the hollow blades 727, annular cavity 731, and contact cold plate 732 that are fixedly connected to the central shaft connecting pipes 732, are thus rotated. 25. The ceramic ring 726 rotates together. It should be noted that the central gear 722, planetary gear 721 and gear ring 720 set here play a speed change role. Depending on the gas flow rate, the speed can be increased (by increasing the number or size of the impeller 704 to obtain greater torque) or decreased. To decrease the speed, the transmission direction of the gear ring 720-impeller shaft 705 can be reversed (i.e., the impeller shaft 705 is fixed coaxially with the guide shroud 702, and the central gear 722 is fixed coaxially with one of the central shaft connecting pipes 732). If the gas dynamics change, it can be replaced with an electric gearbox. The gas passing through impeller 704 will flow to the air inlet 710 under the guidance of guide shroud 702, and then enter the refrigerated drying housing 701 through the air inlet 710. At this time, the gas will be distributed into the gaps between all the contact cooling plates 725, and this part of the gas is in motion. At the same time, the contact cooling plates 725 are rotating. The rotation of the contact cooling plates 725 will cause the gas entering the gaps between all the contact cooling plates 725 to rotate along with them through the viscous force between the contact cooling plates 725 (assuming that the contact cooling plates 725 do not rotate, the gas will flow directly). The gas flows towards the axis of the contact cooling plate 725, which is the hollow blade 727. This means the gas flow path is not straight; it is deflected by the contact cooling plate 725, resulting in an arc-shaped flow path. It's important to note that the smaller the gap between the contact cooling plates 725, the more significant the effect. However, it cannot be too small, otherwise the gas flow resistance will be too high. Therefore, a compromise must be made between the number of contact cooling plates 725 and their gap. In other words, the number of contact cooling plates 725 can be increased to increase the cross-sectional area of ​​the gas flow. Simultaneously, the faster the rotation speed of the contact cooling plate 725, the greater the deviation of this arc, eventually becoming a spiral. This results in the actual contact area of ​​the gas being larger than the contact area of ​​the contact cooling plate 725 in its stationary state. Increasing the contact area between the gas and the contact cooling plate 725 improves the efficiency of refrigeration drying. Finally, the gas flows through the axis of the contact cooling plate 725, which is the hollow blade 727, to the nozzle 707, and then exits the refrigerated dryer 7 through the exhaust pipe 706.

[0034] The above process requires cooling of the impeller shaft 705, therefore refrigerant needs to be injected into the contact cold plate 725 and circulated (the refrigerant is pumped into the contact cold plate 725 by the compressor). Specifically, the refrigerant flow pipe is connected to two rotating connectors 715, one for injection and one for return. Then, the refrigerant enters the shaft tube 712 through the refrigerant inlet 713, and is finally guided and distributed to one of the spaces in the corresponding central shaft connecting pipe 732. Then, it is guided by the hollow blades 727 to an independent space in the annular cavity 731, and then discharged into the contact cold plate 725 through one of the refrigerant flow windows 729. It is then guided and distributed by the arc-shaped guide strips 728 to make more even contact with the contact cold plate 725, and finally flows to the refrigerant flow window 729 at the other end. Then, it flows back to another space in the central shaft connecting pipe 732 through another hollow blade 727, and finally is discharged through the refrigerant outlet 714. It should be noted that the flow pressure of the refrigerant driven by the compressor is greater than the centrifugal force generated by the refrigerant driven by the contact cold plate 725.

[0035] The cooled liquid will settle in the water collection tank 708. The water collection tank 708 and the flow guide 702 are equipped with liquid level sensors. When the liquid level reaches the set value, the electric valve inside the drain outlet 709 will be opened to discharge it. It should be noted that a small amount of condensate will also be thrown out by the rotating contact plate 725 at the air inlet 710. Therefore, a drain outlet also needs to be set at the bottom of the flow guide 702, and an electric valve also needs to be installed in the drain outlet.

Claims

1. A nitrogen production system for oilfields in high-temperature, water-scarce environments, characterized in that: The system includes an air compressor (1), an oil separator (2), a cooler (3), a filter (4), a refrigerated dryer (7), a second separator (8), an instrument air storage tank (9), and a PSA nitrogen generation system (10) connected sequentially along the air flow path; it also includes a bypass pipeline between the filter (4) and the refrigerated dryer (7), on which an air cooler (5) and a separator (6) are provided, and control valves V1 and V2 are provided; it also includes a temperature sensor and a controller for controlling the opening and closing states of valves V1 and V2 according to the compressed air temperature; The refrigerated dryer (7) includes a refrigerated drying shell (701). The circumferential surface of the inner wall of the refrigerated drying shell (701) is provided with a plurality of embedded rotating grooves (724) along its own axis. A ceramic ring (726) is rotatably installed in each embedded rotating groove (724). A contact cooling plate (725) with a hollow interior is fixedly installed in each ceramic ring (726). A circular cavity (731) is fixedly installed at the axial part of the contact cooling plate (725). The annular cavity (731) is divided into two independent spaces. The two independent spaces are connected to the interior of the contact cold plate (725) through a refrigerant flow window (729) opened on the annular cavity (731). Multiple concentric arc-shaped guide strips (728) are symmetrically fixed on both sides of the inner wall of the contact cold plate (725). The diameter of each arc-shaped guide strip (728) on the same side is different, and there is a gap between two adjacent arc-shaped guide strips (728). A channel aligned with the refrigerant flow window (729) is provided between the arc-shaped guide strips (728) on both sides. The inner side of the annular cavity (731) is fixedly connected to the central shaft connecting tube (732) by four hollow blades (727). The interior of the central shaft connecting tube (732) is divided into two independent spaces by the second partition plate (730). The two independent spaces in the central shaft connecting tube (732) are connected to the corresponding independent spaces in the annular cavity (731) by three hollow blades (727).

2. A nitrogen production system for oilfields in high-temperature, water-scarce environments according to claim 1, characterized in that: The air cooler (5) is a composite air cooler, which adopts a plate-fin type or a heat transfer structure with a vortex generator. The controller is a PLC, which can receive temperature sensor signals and automatically control the opening and closing of valves V1 and V2 to stabilize the gas temperature at 20~40℃.

3. A nitrogen production system for oilfields in high-temperature, water-scarce environments according to claim 2, characterized in that: All the central axis connecting tubes (732) are connected in series and coaxially fixed and aligned. The axial length of the central axis connecting tube (732) is greater than the axial length of the contact cold plate (725), so that there is a gap between two adjacent contact cold plates (725).

4. A nitrogen production system for oilfields in high-temperature, water-scarce environments according to claim 3, characterized in that: The refrigerated drying housing (701) has an air inlet (710) and a drain outlet (711). A water collection pool (708) communicating with the interior of the refrigerated drying housing (701) is fixedly installed at the drain outlet (711). A drain port (709) is fixedly provided at the bottom of the water collection pool (708). An electric valve is provided inside the drain port (709).

5. A nitrogen production system for oilfields in high-temperature, water-scarce environments according to claim 4, characterized in that: A flow guide (702) is fixedly and sealed outside the air inlet (710) of the refrigerated drying housing (701). The flow guide (702) is coaxially arranged with the refrigerated drying housing (701). An air inlet pipe (703) is fixedly connected to the side axis of the flow guide (702). An impeller (704) is rotatably installed inside the air inlet pipe (703). An impeller shaft (705) is fixedly installed at the axial center of the impeller (704). A gap is left between the inner wall of the flow guide (702) facing the air inlet pipe (703) and the side of the refrigerated drying housing (701). A toothed ring housing (717) is installed in this gap. The toothed ring housing (717) is fixed on the refrigerated drying housing (701). The internal gear ring (720) is rotatably mounted. A central gear (722) is rotatably fitted at the center position of the inner side of the gear ring (720). The central gear (722) and the gear ring (720) are driven by three planetary gears (721). All the planetary gears (721) are rotatably mounted on the planetary gear support plate (718). The planetary gear support plate (718) is fixed to the gear ring housing (717) by the planetary gear support plate fixing block (719). A sealing cover plate (716) is also fixedly and sealed on the gear ring housing (717). The impeller shaft (705) passes through the sealing cover plate (716) and the planetary gear support plate (718) and is fixedly fitted with the central gear (722).

6. A nitrogen production system for oilfields in high-temperature, water-scarce environments according to claim 5, characterized in that: The toothed ring (720) is coaxially fixedly engaged with a central shaft connecting tube (732) at one end via a shaft rod, which is also used to seal one end of the central shaft connecting tube (732); the central shaft connecting tube (732) at the other end is coaxially fixedly connected to a shaft tube (712), and the shaft tube (712) is divided into two independent spaces by a first partition plate (723). The two independent spaces in the shaft tube (712) are connected to the two independent spaces in the central shaft connecting tube (732), and the first partition plate (723) is aligned with the second partition plate (730). The refrigerated drying shell (701) is provided with a port (707) at the axial position on the side away from the impeller shaft (705). An exhaust pipe (706) is fixedly connected to the port (707). The shaft tube (712) is rotary sealed and extends to the outside of the exhaust pipe (706). The shaft tube (712) is provided with a refrigerant inlet (713) and a refrigerant outlet (714) at the position outside the exhaust pipe (706). The refrigerant inlet (713) and the refrigerant outlet (714) are respectively connected to two independent spaces in the shaft tube (712). Two rotary connectors (715) are fixedly installed on the exhaust pipe (706). Both rotary connectors (715) are rotary sealed with the shaft tube (712). The two rotary connectors (715) are respectively connected to the refrigerant inlet (713) and the refrigerant outlet (714).

7. A nitrogen production method for oilfields in high-temperature and water-scarce environments, using the nitrogen production system for oilfields in high-temperature and water-scarce environments as described in claim 2, characterized in that, Includes the following steps: Step 1: After being compressed by the air compressor (1), the air is preliminarily treated by the oil separator (2), cooler (3) and filter (4) in sequence, and its temperature is detected. Step 2: If the temperature exceeds the set threshold, open valves V1 and V2 so that the gas is cooled and separated by the air cooler (5) and separator (6) and then enters the refrigerated dryer (7). Step 3: If the temperature is lower than the set threshold, turn off V1 and V2 to allow the gas to enter the refrigerated dryer directly (7). Step 4: After being processed by the refrigerated dryer (7), the gas enters the instrument air storage tank (9) through the second separator (8) and finally enters the PSA nitrogen generation system (10) to produce nitrogen.

8. A nitrogen production method for oilfields in high-temperature, water-scarce environments according to claim 7, characterized in that: In steps 2 and 3, the threshold is set to 40°C; by controlling the opening and closing of valves V1 and V2, the gas temperature entering the PSA nitrogen generation system (10) is maintained at 20~40°C.

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