Electric dehydration equipment for crude oil containing natural gas

Abstract

The utility model discloses electric dehydration equipment for crude oil containing natural gas, which relates to the technical field of petroleum and natural gas processing and comprises a tank body, a transformer, an internal part and a pipeline, the interior of the tank body is sequentially divided into a gas-liquid separation area, an oil-water preliminary separation area, an electric removal area and an oil storage area; a crude oil inlet is formed in the side wall, located in the gas-liquid separation area, of the tank body, and the inlet distributor is located at the crude oil inlet in the tank body; the steady flow plate and the oil-water separation filler are arranged at the downstream of the gas-liquid separation area; the electrode plate is positioned in the electric stripping area and is connected with the transformer; the separation weir plate is used for separating the electric separation area from the oil storage area, and the oil storage area is provided with an oil purification self-vortex-prevention device and an oil phase opening; the demister is arranged at a gas phase opening in the top of the tank body; through the integrated design, the crude oil treatment process is simplified, the number of equipment and the occupied area are reduced, the investment and the operation and maintenance cost are reduced, and the treatment efficiency and the safety are improved.

Description

Technical Field

[0001] This utility model relates to the field of oil and natural gas processing technology, and in particular to an electric dehydration device for crude oil containing natural gas. Background Technology

[0002] During crude oil extraction, the well products are multiphase mixtures containing crude oil, natural gas, water, and impurities, which typically require pretreatment. Three-phase separators are usually the first piece of equipment at the wellhead to process the produced fluid in oilfield surface engineering. The main process of a three-phase separator is as follows: the oil-water-gas mixture enters the separator through the inlet separation device. Gas-liquid separation is achieved through the inlet separation device. The separated gas exits the separator from the other end, while the entrained liquid droplets settle during their movement. The liquid separated after the inlet separation device first passes through a flow stabilization device to reduce turbulence, and then through parallel plate packing or coalescing packing to further separate the oil and water phases. The water phase is at the bottom, and the oil phase is at the top. Under the action of the weir, the oil phase enters the oil chamber, thus achieving the separation of the oil, gas, and water phases. The crude oil separated by the three-phase separator does not meet the water content requirements for oil transportation and requires further processing using an electrostatic dehydration process. Electrodehydration uses an electric field to enhance coalescence, causing tiny water droplets dispersed in crude oil to coalesce into larger droplets. These larger droplets then continue to settle, achieving further separation of oil and water.

[0003] Traditional crude oil processing typically employs a series connection of a three-phase separator and an electrostatic dehydration tank. This process involves dispersed equipment, a long process flow, a large footprint, complex pipeline connections, high investment and maintenance costs, increased energy consumption due to intermediate storage tanks and pumping stages, and the potential for oil and gas volatilization and leakage. There is an urgent need for an integrated device that can separate natural gas and crude oil within a single unit, and desalt and dehydrate the crude oil, simplifying the crude oil processing flow and improving safety and energy efficiency. Utility Model Content

[0004] This invention provides an electric dehydration device for crude oil containing natural gas, which can solve the problems in the existing technology where the traditional crude oil processing process usually adopts a series process of three-phase separator and electric dehydration tank, which increases energy consumption in intermediate storage tanks and pumping links, and poses a risk of oil and gas volatilization and leakage.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] An electrostatic dehydration device for crude oil containing natural gas includes a tank, a transformer, internal components, and pipelines. The internal components include an inlet distributor, a flow stabilizer, oil-water separation packing, an electrode plate, a separating weir plate, and a demister. The tank is internally divided into a gas-liquid separation zone, a preliminary oil-water separation zone, an electrostatic dehydration zone, and an oil storage zone. A crude oil inlet is located on the side wall of the gas-liquid separation zone, and the inlet distributor is located at the crude oil inlet inside the tank. The flow stabilizer and oil-water separation packing are located downstream of the gas-liquid separation zone. The electrode plate is located in the electrostatic dehydration zone and connected to the transformer. The separating weir plate separates the electrostatic dehydration zone from the oil storage zone, and the oil storage zone is equipped with a self-cleaning anti-vortex device and an oil phase inlet. The demister is located at the gas phase inlet at the top of the tank.

[0007] Preferably, the inlet distributor is a blade-type inlet device or a vortex-type inlet device.

[0008] Preferably, the electrode plate is a horizontal multi-layer electrode plate structure, including an upper grounding electrode plate, a middle high-voltage electrode plate and a lower grounding electrode plate, forming a strong electric field region and a weak electric field region.

[0009] Preferably, the oil-water separation packing is a wire mesh or blade coalescing packing.

[0010] Preferably, it also includes a backwashing system, which includes a flushing water pipe, a drain pipe, and a bottom nozzle.

[0011] Preferably, the tank sidewall is provided with a low liquid level switch, which is interlocked with the transformer to cut off the power supply when the liquid level is lower than the set value.

[0012] Preferably, the oil storage area and the water phase outlet are respectively equipped with an oil phase level gauge and a water phase level gauge, and are interlocked with the oil phase level control valve and the water phase level control valve.

[0013] Preferably, the demisting packing of the demister includes wire mesh type and blade type.

[0014] Preferably, the nozzles of the backwashing system are evenly distributed along the bottom of the tank and the jet coverage areas overlap.

[0015] Preferably, the top of the tank is equipped with a pressure sensor and a pressure control valve.

[0016] The beneficial effects of this utility model are:

[0017] (1) This utility model simplifies the crude oil processing process through integrated design, reduces the number of equipment and floor space, lowers investment and maintenance costs, and improves processing efficiency and safety. At the same time, the backflushing system keeps the inside of the equipment clean and extends its service life.

[0018] (2) The equipment achieves efficient gas-liquid separation through the rational layout of internal components such as inlet distributors, flow stabilizers, and oil-water separation packing. In the electro-dehydration zone, the high-voltage electric field formed by the electrode plates is used to perform deep electro-dehydration treatment on crude oil, causing the tiny water droplets dispersed in the crude oil to coalesce into larger water droplets and settle, thereby achieving further separation of oil and water.

[0019] (3) The equipment is equipped with a low liquid level switch and transformer interlock. When the liquid level is lower than the set value, the power supply is automatically cut off to prevent safety accidents such as gas explosion. At the same time, the oil phase liquid level gauge and the water phase liquid level gauge are interlocked with the oil phase liquid level control valve and the water phase liquid level control valve, respectively. The liquid level is precisely controlled by controlling the discharge rate to ensure the safe and stable operation of the equipment. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the structure of an electric dehydration device for crude oil containing natural gas according to this utility model;

[0022] Figure 2 This is a schematic diagram of the process flow of an electric dehydration device for crude oil containing natural gas, according to this utility model.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Crude oil inlet; 2. Inlet distributor; 3. Flow stabilizer; 4. Oil-water separator packing; 5. Transformer; 6. Electrode plate; 7. Separating weir plate; 8. Demister; 9. Gas phase inlet; 10. Clean oil self-anti-vortex device; 11. Oil phase inlet; 12. Backwash drain port one; 13. Backwash port one; 14. Self-anti-vortex device two; 15. Water phase inlet; 16. Backwash drain port two; 17. Backwash port two; 18. Backwash drain port three; 19. Backwash port three.

[0025] 21. Mixed liquid feed pipe; 22. Pressure sensor; 23. Gas phase outlet pipe; 24. Pressure control valve; 25. Low level switch; 26. Gas-liquid interface level gauge; 27. Aqueous phase level gauge; 28. Oil phase level gauge; 29. ​​Flushing water pipe; 210. Aqueous phase outlet pipe; 211. Aqueous phase level control valve; 212. Oil phase outlet pipe; 213. Oil phase level control valve; 214. Sewage pipe. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figure 1 As shown, this utility model is an electro-dehydration device for crude oil containing natural gas, including a tank, a transformer 5, internal components, and pipelines; the internal components include an inlet distributor 2, a flow stabilizer 3, an oil-water separation packing 4, an electrode plate 6, a separating weir plate 7, and a demister 8; the interior of the tank is sequentially divided into a gas-liquid separation zone, an oil-water preliminary separation zone, an electro-dehydration zone, and an oil storage zone; a crude oil inlet 1 is provided on the side wall of the tank located in the gas-liquid separation zone, and the inlet distributor 2 is located at the crude oil inlet 1 inside the tank; the flow stabilizer 3 and the oil-water separation packing 4 are located downstream of the gas-liquid separation zone; the electrode plate 6 is located in the electro-dehydration zone and connected to the transformer 5; the separating weir plate 7 separates the electro-dehydration zone from the oil storage zone, and the oil storage zone is equipped with a self-cleaning anti-vortex device 10 and an oil phase inlet 11; the demister 8 is located at the gas phase inlet 9 at the top of the tank.

[0028] The crude oil inlet 1 containing natural gas, inlet distributor 2, flow stabilizer 3, and oil-water separation packing 4 form the gas-liquid separation zone and the preliminary oil-water separation zone. The area from the oil-water separation packing 4 to the oil separation weir 7 is the electro-dehydration and desalination zone, and the area from the separation weir 7 to the oil phase outlet 11 is the oil chamber. The three-phase mixture of oil, gas, and water enters the inlet distributor 2 from the crude oil inlet 1, achieving preliminary gas-liquid separation. The liquid phase enters the gas-liquid separation zone at the bottom of the inlet distributor 2, while the gas phase enters from the top of the inlet distributor 2. After gas phase separation, large droplets in the gas phase are separated by the oil-water separation packing 4, and then pass through the top cavity to the demister 8, achieving the separation of small droplets in the gas phase. The gas phase exits the electro-dehydration tank at the gas phase outlet 9. The oil-water mixture first passes through the flow stabilizer 3 to reduce liquid phase turbulence, then through the oil-water separation packing 4 into the desalting and dehydration zone. The salt- and water-containing crude oil passes through a high-voltage electric field in the electro-dehydration zone, formed by electrode plates 6 arranged in the zone. Electrode plates 6 are connected to a transformer 5 via a high-voltage power introduction device. The transformer 5 receives power, introducing a high-voltage current of up to 25-40kV into the electrode plates 6, creating the high-voltage electric field. Salt-containing droplets in the crude oil settle in the electric field, forming a stable oil-water interface. The settled salt phase anti-vortex device 14 and water phase inlet 15 exit the electro-dehydration tank. After oil-water separation, the upper layer of clean oil passes through the separating weir 7 into the oil chamber. The clean oil in the oil chamber exits the electro-dehydration tank through the clean oil anti-vortex device 10 and oil phase inlet 11. The gas-liquid separation zone, the electro-desalination and dehydration zone, and the oil chamber are each equipped with relatively independent backwash and backwash drain outlets. Specifically, the bottom of the gas-liquid separation zone is equipped with backwash drain outlet 318 and backwash outlet 19, the bottom of the electro-desalination and dehydration zone is equipped with flush drain outlet 216 and backwash outlet 17, and the bottom of the oil chamber is equipped with flush drain outlet 12 and backwash outlet 13.

[0029] In terms of technology, such as Figure 2As shown, after the demulsifier is injected into the water- and gas-containing crude oil, it enters the electro-dehydration unit through the mixed liquid feed pipe 21 at the top of the unit. It first passes through the inlet distributor 2 for preliminary gas-liquid separation. The gas accumulates at the top of the unit and is then demisted by the demister 8 at the outlet before proceeding to subsequent processing units. The liquid accumulates at the bottom of the tank, first passing through the flow stabilizer 3 for flow stabilization, then through the coalescing packing for coalescence, before entering the electro-dehydration section. A pressure sensor 22 is installed at the top of the electro-dehydration tank, and a pressure control valve 24 is installed on the gas phase outlet pipe 23. The pressure sensor 22 and the pressure control valve 24 are interlocked, controlling the operating pressure of the electro-dehydration tank through the exhaust rate and exhaust pressure. A low-level switch 25 is installed on the side of the electro-dehydration tank and interlocked with the transformer 5. If the crude oil fails to reach the low-level switch 25, the transformer 5 will stop supplying power to prevent gas explosions during the operation of the electro-dehydration unit. The liquid level in the electro-dehydration zone must completely submerge the electrode plate 6. The electrostatic desalination section is equipped with a gas-liquid interface level gauge 26. The transformer 5 is connected to the electrode plate 6 via a high-voltage electrical connection device to perform deep separation of oil and water. The separated water accumulates in the lower layer. The water phase level gauge 27 and the water phase level control valve 211 are interlocked. The water phase level is controlled by controlling the water phase discharge rate and discharged through the water phase outlet pipe 210. The separated oil accumulates in the upper layer. A weir plate is installed at the right end of the electrostatic desalination section. When the oil layer level is higher than the weir plate, the crude oil enters the crude oil chamber. The oil chamber is equipped with an oil phase level gauge 28. The oil phase outlet pipe 212 is equipped with an oil phase level control valve 213. The oil phase level gauge 28 and the oil phase level control valve 213 are interlocked. The oil phase level is controlled by controlling the oil phase discharge rate. An oil drain port is installed at the bottom of the crude oil chamber. The crude oil is discharged from the tank through the oil phase outlet pipe 212 and sent to the subsequent oil phase treatment facilities. When backwashing is required, the backwash water comes from outside the boundary and enters the bottom of the electric dehydration tank through the backwash water pipe 29 for backwashing. The impurities washed out are discharged outside the tank through the drain pipe 214.

[0030] The produced fluid, consisting of an oil, gas, and water phase, enters the electrostatic dehydration tank body through the inlet. The inlet distributor 2 can be an inlet baffle, a semi-open pipe, a vane-type inlet device, or a vortex-type inlet device. Vane-type and vortex-type inlet devices can effectively handle the fluid at the inlet nozzle and maximize gas-liquid separation. Other inlet devices may result in poor gas-liquid distribution and increased gas-liquid entrainment. Therefore, this invention preferentially uses vane-type or vortex-type inlet devices.

[0031] Blade-type inlet devices are used in separators requiring good airflow distribution and minimal shear and pressure drop. Compared to simple deflectors, the advantages of this device include: reduced backmixing, thus improving operating performance; more stable level control; and reduced foaming.

[0032] The working principle of a blade-type inlet device is to use a set of curved blades to smoothly divide the incoming airflow into different parts to adapt to the overall geometry of the inlet nozzle and the length of the distributor. To achieve this effect, the blades start with a wide gap and gradually reduce the gap, designed into a special conical shape.

[0033] The flow stabilizer 3 is a porous baffle installed perpendicular to the flow direction in the liquid collection area of ​​the separator to reduce fluctuations caused by fluid entry. During the operation of the electrostatic dehydrator, fluctuations in the container must be suppressed to ensure the proper functioning of the level controller, safety valve, and overflow outlet.

[0034] To further enhance liquid-liquid separation, coalescing packing is used, which can reduce size and increase produced fluid throughput without changing the overall separation efficiency. Figure 1 For example, oil-water separation packing 4 is used. When gas and liquid enter the container, the flow velocity is relatively high. Only after the fluid is evenly distributed throughout the entire usable cross-section can a good flow state be achieved, resulting in ideal separation. Oil-water separation packing 4 is used to enhance the rapid and efficient separation of oil and water. If the produced fluid does not contain wax or other contaminants, oil-water separation packing 4 can be used to increase the liquid handling capacity of the gravity separation section, and the coalescer causes small droplets to coalesce into larger droplets. Oil-water separation packing 4 can be either wire mesh or blade type.

[0035] A demister 8 is installed at the gas phase inlet 9 of the electrostatic dehydration tank. The basic principle of the demister 8 is that different phases of different densities in a fluid have different momentum. If the two-phase flow suddenly changes direction, the heavier fluid particles with greater momentum cannot change direction as quickly as the lighter fluid, thus separation occurs. Momentum separation is commonly used for two-phase flow separation. If the gravity acting on the droplets is greater than the resistance of the airflow acting on the droplets, the droplets will settle from the gas phase. Very small droplets cannot actually be separated by gravity. These droplets can be coalesced into larger droplets, which then settle due to gravity. The coalescence device in the separator forces the gas through a bend; the droplet momentum causes them to collide with each other or with the coalescence device, forming larger droplets. These larger droplets can settle from the gas due to gravity. Demisting packing includes wire mesh and blade types. Its function is to coalesce the small droplets still present in the gas phase after initial separation into larger droplets, allowing them to fall from the rising gas phase under their own gravity. Blade demister: A blade demister is a highly efficient demisting device, mainly composed of an arrangement of irregular parallel plates. Due to the blade design, the liquid-containing gas within the blade bundle undergoes several forced changes in direction, causing heavier liquid droplets to be thrown against the wet wall, thus achieving deep gas-liquid separation. It is suitable for both fouled and clean environments. The blade demister, made of curved parallel plates, collects and discharges the separated liquid and can be disassembled through a manhole. Advantages of blade demisters include: adaptability to handling components prone to fouling.

[0036] In the electro-desalination and dehydration zone, there is a transformer 5, a low-level switch 25, and electrode plates 6. To prevent explosions caused by gases generated during the operation of the electro-dehydration unit, an explosion-proof low-level switch 25 is designed and installed on the side of the electro-dehydration tank. It is interlocked with the control panel. If the raw oil in the tank does not completely submerge the electrode plates 6, the transformer 5 will stop supplying power; the transformer 5 will only supply power when the required level is reached.

[0037] Electrode plate 6 can be a combined horizontal or vertical electrode plate. With horizontal electrodes, the electro-dehydration tank consists of two or three layers of electrode plates, with a single electrode plate providing power. With three layers, generally the middle layer is powered, while the top and bottom layers are grounded. A strong electric field region is formed between the upper and middle layers, and a weak electric field region is formed between the middle and lower layers. With two layers, each electrode plate is powered, creating a strong electric field region between them. AC dehydration equipment was developed earlier, has mature technology, and a simple structure; using vertical electrodes, a single-phase half-wave rectified DC power supply is employed, with the DC voltage on both the positive and negative electrodes being a half-sine wave. Because the voltages on the positive and negative electrodes alternate, an alternating electric field is formed between the lower end plate of the electrode and the oil-water interface. This electric field is generally designed to be a weak field, with the voltage between the positive and negative electrodes increasing from bottom to top as a weak DC electric field, a medium DC electric field, and a strong DC electric field.

[0038] Raw oil often contains mechanical impurities and silt, which accumulate at the bottom of the electrostatic dehydration tank, reducing its effective space, water volume, and residence time, thus affecting effluent quality. Therefore, a continuous backwashing system is designed into the electrostatic dehydration tank to promptly remove settled solids and silt. The backwashing system consists of backwash water pipe 29, backwash internals, and a drain pipe 214. By injecting backwash water, the system fluidizes the solid particles settled at the bottom of the container into slurry, which is then discharged into the sand treatment / produced water system for further treatment. The sandblasting system injects purified water into the bottom of the separator. Several nozzles are installed on the distribution pipe according to the separator size. Due to the close proximity of the nozzles, the jets of purified water overlap effectively, fluidizing silt in specific areas and promoting gas discharge from the sand outlet. The advantages of the sandblasting system include: effective jet distribution; good sand removal capability; excellent scale inhibition performance; and low pressure drop.

[0039] The above description provides a detailed account of one embodiment of the present invention. However, this description is merely a preferred embodiment and should not be construed as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the claims of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A crude oil electrostatic dehydration device containing natural gas, characterized in that, The system includes a tank, a transformer (5), internal components, and pipelines. The internal components include an inlet distributor (2), a flow stabilizer (3), an oil-water separation packing (4), an electrode plate (6), a separating weir plate (7), and a demister (8). The tank is divided into a gas-liquid separation zone, a preliminary oil-water separation zone, an electro-desorption zone, and an oil storage zone. The tank has a crude oil inlet (1) on the side wall of the gas-liquid separation zone, and the inlet distributor (2) is located at the crude oil inlet (1) inside the tank. The flow stabilizer (3) and the oil-water separation packing (4) are located downstream of the gas-liquid separation zone. The electrode plate (6) is located in the electro-desorption zone and connected to the transformer (5). The separating weir plate (7) separates the electro-desorption zone from the oil storage zone. The oil storage zone is equipped with a self-cleaning anti-vortex device (10) and an oil phase inlet (11). The demister (8) is located at the gas phase inlet (9) at the top of the tank.

2. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The inlet distributor (2) is a blade-type inlet device or a vortex-type inlet device.

3. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The electrode plate (6) is a horizontal multi-layer electrode plate structure, including an upper grounding electrode plate, a middle high-voltage electrode plate and a lower grounding electrode plate, forming a strong electric field region and a weak electric field region.

4. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The oil-water separation packing (4) is a wire mesh or blade coalescing packing.

5. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, It also includes a backwashing system, which includes a flushing water pipe (29), a drain pipe (214) and a bottom nozzle.

6. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The tank sidewall is equipped with a low liquid level switch (25), which is interlocked with the transformer (5) to cut off the power supply when the liquid level is lower than the set value.

7. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The oil storage area and the water phase port (15) are respectively equipped with an oil phase level gauge (28) and a water phase level gauge (27), which are interlocked with the oil phase level control valve (213) and the water phase level control valve (211).

8. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The demisting filler of the demister (8) includes wire mesh and blade type.

9. The crude oil electrostatic dehydration equipment containing natural gas according to claim 5, characterized in that, The nozzles of the backwashing system are evenly distributed along the bottom of the tank and the jet coverage areas overlap.

10. The crude oil electrostatic dehydration equipment containing natural gas according to claim 1, characterized in that, The top of the tank is equipped with a pressure sensor (22) and a pressure control valve (24).

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