A crude oil electric dehydration system and working method utilizing solar energy

Abstract

The present invention discloses a crude oil electric dehydration system that utilizes solar energy. This system preheats crude oil emulsions and efficiently separates oil and water, achieving direct electrical energy recovery and significantly reducing the operating and maintenance costs of oilfield surface projects. The system utilizes the following technical solutions: a preheating and oil-water separation system, a steam direct expansion system, an organic Rankine cycle system, and a concentrated solar thermal collection system. The concentrated solar thermal collection system exchanges heat with the organic Rankine cycle system via a fourth heat exchanger. The organic Rankine cycle system transfers heat to the preheating and oil-water separation system via the first heat exchanger. The concentrated solar thermal collection system exchanges heat with the steam direct expansion system via a second heat exchanger. The electricity generated by the organic Rankine turbine expander and steam turbine expander is supplied to the dehydrator power supply, achieving electrical dehydration of the crude oil.

Description

Technical Field

[0001] The present invention relates to the technical field of multiphase separation of oil and gas gathering and transportation systems, and relates to a crude oil electric dehydration system utilizing solar energy and a working method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Traditional crude oil electric dehydration systems require a large amount of electricity during operation, which leads to high system energy consumption and significantly increases the operating costs of oilfield surface projects. In addition, before entering the electric dehydration equipment, in order to improve the oil-water separation efficiency, the crude oil usually needs to be heated and pre-treated. This not only requires additional heating equipment and energy consumption, but also makes the operation process of the crude oil electric dehydration system complicated and the operating efficiency low.

[0004] Oilfield surface facilities, especially electric dehydration systems, typically require a large amount of electricity. Solar energy, as a renewable energy source, holds great promise for application in medium- and low-temperature thermal power generation. However, existing solar power generation systems are difficult to directly and effectively integrate into these systems, failing to fully meet the energy needs of crude oil electric dehydration and resulting in low overall solar energy utilization.

[0005] Existing patent CN106587460A discloses a solar oilfield wastewater treatment system that uses solar panels to convert solar energy into electricity for storage or supply to oil removal components. However, this system only generates a limited amount of electricity through photoelectric conversion, fails to fully utilize the solar thermal effect in the oil-water separation process, and results in low overall power generation and thermal efficiency. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a crude oil electric dehydration system that utilizes solar energy. It can not only quickly and efficiently preheat the crude oil emulsion and efficiently separate the oil and water, but also realize the direct recovery and utilization of electrical energy; it greatly reduces the operation and maintenance costs of oilfield surface projects; at the same time, the system makes cascaded use of solar energy, effectively improving the thermal efficiency and power generation efficiency of the dehydration system.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A crude oil electric dehydration system utilizing solar energy, comprising a preheating and oil-water separation system, a water vapor direct expansion system, an organic Rankine cycle system, and a concentrated solar heat collection cycle system;

[0009] The concentrating solar thermal collection cycle system includes a second heat exchanger and a fourth heat exchanger, and the concentrating solar thermal collection cycle system exchanges heat with the organic Rankine cycle system through the fourth heat exchanger; the organic Rankine cycle system includes a first heat exchanger and an organic Rankine turbine expander; the organic Rankine cycle system transfers heat to the preheating and oil-water separation system through the first heat exchanger;

[0010] The concentrating solar thermal circulation system exchanges heat with the water vapor direct expansion system through the second heat exchanger; the water vapor direct expansion system includes a dehydrator power supply and a steam turbine expander; the electrical energy generated by the organic Rankine turbine expander and the steam turbine expander is supplied to the dehydrator power supply to realize electrical dehydration of crude oil.

[0011] Furthermore, the preheating and oil-water separation system includes a crude oil emulsion pump, the working fluid outlet side of the crude oil emulsion pump is connected to the cold flow inlet side of the first heat exchanger, and the cold flow outlet side of the first heat exchanger is connected to the liquid inlet of the horizontal electric dehydrator.

[0012] Furthermore, the water vapor direct expansion system includes a horizontal electric dehydrator, the water outlet of the horizontal electric dehydrator is connected to the inlet side of the throttle valve, the outlet side of the throttle valve is connected to the cold flow inlet side of the second heat exchanger, the cold flow outlet side of the second heat exchanger is connected to the inlet side of the steam turbine expander, the outlet side of the steam turbine expander is connected to the hot flow inlet side of the third heat exchanger, and the oil outlet II of the horizontal electric dehydrator is connected to the cold flow inlet side of the third heat exchanger; the cold flow outlet side of the third heat exchanger is connected to the crude oil gathering and transportation pipeline network.

[0013] Furthermore, the organic Rankine cycle system includes an organic working fluid pump, the outlet side of the organic working fluid pump is connected to the cold flow inlet side of the fourth heat exchanger, the cold flow outlet side of the fourth heat exchanger is connected to the inlet side of the organic Rankine turbine expander, the outlet side of the organic Rankine turbine expander is connected to the hot flow inlet side of the first heat exchanger, and the hot flow outlet side of the first heat exchanger is connected to the inlet side of the organic working fluid pump.

[0014] Furthermore, the concentrating solar thermal collection cycle system includes a heliostat, which absorbs sunlight and transfers heat to a heat absorber. The working fluid outlet side of the heat absorber is connected to the heat flow inlet side of the second heat exchanger, the heat flow outlet side of the second heat exchanger is connected to the heat flow inlet side of the fourth heat exchanger, the heat flow outlet side of the fourth heat exchanger is connected to the working fluid inlet side of the molten salt pump, and the working fluid outlet side of the molten salt pump is connected to the working fluid inlet side of the heat absorber.

[0015] Furthermore, the working fluid at the working fluid inlet side of the crude oil emulsion pump is crude oil emulsion, and the water content by mass fraction thereof is not greater than 30%.

[0016] Furthermore, the working medium of the oil outlet II of the horizontal electric dehydrator is dehydrated crude oil, and its water content is less than or equal to 0.5% by mass;

[0017] Furthermore, the working medium of the water outlet III of the horizontal electric dehydrator is oily wastewater, and the oil content thereof is not greater than 1000 mg / L.

[0018] Furthermore, the hot flow outlet side of the third heat exchanger is connected to a sewage treatment station.

[0019] A method for operating a crude oil electric dehydration system using solar energy, characterized by comprising the following steps:

[0020] S1: Using solar energy to heat the molten salt in the solar thermal collection circulation system;

[0021] S2: After being pressurized by the organic working fluid pump, the organic working fluid is heated and vaporized by the molten salt in the fourth heat exchanger, and then enters the organic Rankine turbine expander to expand and generate power. After completing the power generation process, the organic working fluid exhaust gas is used to preheat the crude oil emulsion in the first heat exchanger;

[0022] S3: preheating the crude oil emulsion through the first heat exchanger, and supplying the electric energy obtained by the organic Rankine turbine expander to the horizontal electric dehydrator to separate the preheated crude oil emulsion into oil and water;

[0023] S4: The oily wastewater separated from the crude oil emulsion is gasified into water vapor by high-temperature molten salt in the second heat exchanger. The water vapor enters the steam turbine expander to expand and generate electricity, and the obtained electricity is supplied to the horizontal electric dehydrator to achieve oil-water separation in the crude oil emulsion through electric heating.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention cleverly combines the crude oil electric dehydration process, the organic Rankine cycle, solar thermal power generation technology, and steam expansion power generation technology. It utilizes the waste heat of the organic working fluid exhaust gas to preheat the crude oil emulsion, thereby reducing the viscosity of the crude oil emulsion and the strength of the oil-water interface film, accelerating the coalescence and sedimentation of water droplets in the oil, and effectively improving the oil-water separation efficiency while simplifying the treatment process and reducing operating costs. By heating the wastewater removed from the crude oil, the water vapor is expanded to generate power, and the power is integrated with the power generated by the organic Rankine cycle to supply the electric dehydrator, which greatly reduces the energy consumption of crude oil dehydration. The water vapor exhaust gas is heat-exchanged with the dehydrated crude oil, which not only increases the crude oil output temperature to reduce the crude oil pipeline resistance, but also enables the water vapor phase change liquefaction to facilitate subsequent transfer and processing. A low-focusing concentrating solar collector is used to convert solar radiation into medium- and low-temperature thermal energy, which is used as a direct heat source for water vapor expansion and the organic Rankine cycle, while indirectly providing heat energy for the preheating of the crude oil emulsion, thus realizing the cascade utilization of solar energy.

[0026] The present invention not only ensures rapid pretreatment of crude oil emulsion and efficient oil-water separation, but also achieves self-sufficiency in electrical energy; while solving the problem of complexity and inefficiency in the crude oil dehydration process, it significantly reduces the operation and maintenance costs of oilfield surface projects; at the same time, it realizes the cascade utilization of solar energy, effectively improving the thermal efficiency and power generation efficiency of the system; it has the advantages of reasonable and compact structure, safe and flexible control, high efficiency and energy saving, strong practicality and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 Schematic diagram of the system of the present invention.

[0029] In the figure: 1. Crude oil emulsion pump; 2. First heat exchanger; 3. Horizontal electric dehydrator; 4. Throttle valve; 5. Second heat exchanger; 6. Steam turbine expander; 7. Third heat exchanger; 8. Dehydrator power supply; 9. Organic working fluid pump; 10. Fourth heat exchanger; 11. Organic Rankine turbine expander; 12. Molten salt pump; 13. Heat absorber; 14. Heliostat. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly indicated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprising" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations;

[0032] The embodiment of the present invention discloses a crude oil electric dehydration system using solar energy, such as Figure 1As shown, it includes a preheating and oil-water separation system, a water vapor direct expansion system, an organic Rankine cycle system, and a concentrating solar thermal collection cycle system; the concentrating solar thermal collection cycle system includes a second heat exchanger 5 and a fourth heat exchanger 10, and the concentrating solar thermal collection cycle system realizes heat exchange with the organic Rankine cycle system through the fourth heat exchanger 10; the organic Rankine cycle system includes a first heat exchanger 2 and an organic Rankine turbine expander 11; the organic Rankine cycle system transfers heat to the preheating and oil-water separation system through the first heat exchanger 2; the concentrating solar thermal collection cycle system realizes heat exchange with the water vapor direct expansion system through the second heat exchanger 5; the water vapor direct expansion system includes a dehydrator power supply 8 and a steam turbine expander 6; the electric energy generated by the organic Rankine turbine expander 11 and the steam turbine expander 6 is supplied to the dehydrator power supply 8 to realize electric dehydration of crude oil. By heating the wastewater removed from the crude oil, the water vapor expands to generate electricity, which is then integrated with the electricity generated by the organic Rankine cycle to supply the electric dehydrator, significantly reducing the energy consumption of crude oil dehydration. The heat exchange between the water vapor exhaust gas and the dehydrated crude oil not only increases the crude oil output temperature to reduce the crude oil pipeline resistance, but also causes the water vapor to liquefy in phase change, facilitating subsequent transfer and processing.

[0033] The preheating and oil-water separation system also includes a crude oil emulsion pump 1. The working medium outlet side of the crude oil emulsion pump 1 is connected to the cold flow inlet side of the first heat exchanger 2. The crude oil emulsion extracted from the oil well is pressurized and transported to the first heat exchanger 2 through the crude oil emulsion pump 1. The cold flow outlet side of the first heat exchanger 2 is connected to the liquid inlet I of the horizontal electric dehydrator 3. The crude oil emulsion enters the horizontal electric dehydrator 3 through the liquid inlet I for oil-water separation. The working medium on the working medium inlet side of the crude oil emulsion pump 1 is crude oil emulsion, and its water content by mass fraction is not greater than 30%.

[0034] The water vapor direct expansion system also includes a horizontal electric dehydrator 3, the water outlet III of the horizontal electric dehydrator 3 is connected to the inlet side of the throttle valve 4, the outlet side of the throttle valve 4 is connected to the cold flow inlet side of the second heat exchanger 5, the cold flow outlet side of the second heat exchanger 5 is connected to the inlet side of the steam turbine expander 6, the oily wastewater separated from the crude oil emulsion is discharged from the water outlet III of the horizontal electric dehydrator 3, after the flow rate and pressure are adjusted by the throttle valve 4, it enters the second heat exchanger 5, is heated by the high-temperature molten salt and vaporized into water vapor, and then the high-temperature and high-pressure water is Steam enters the steam turbine expander 6, where it expands and generates electricity. The outlet of the steam turbine expander 6 is connected to the hot flow inlet of the third heat exchanger 7. The oil outlet II of the horizontal electric dehydrator 3 is connected to the cold flow inlet of the third heat exchanger 7. The steam exhaust gas after power generation exchanges heat with the dehydrated crude oil discharged from the oil outlet II in the third heat exchanger 7. The electricity generated by the steam turbine expander 6 is supplied to the dehydrator power supply 8. The working medium of the oil outlet II of the horizontal electric dehydrator 3 is dehydrated crude oil with a water content of less than or equal to 0.5%. The working medium of the water outlet III of the horizontal electric dehydrator 3 is oily wastewater with an oil content of no more than 1000 mg / L. The cold flow outlet of the third heat exchanger 7 is connected to the crude oil gathering and transportation network, while the hot flow outlet of the third heat exchanger 7 is connected to the sewage treatment plant. By heating the wastewater removed from the crude oil, the water vapor expands and generates electricity. This is then integrated with the electricity generated by the organic Rankine cycle to supply the electric dehydrator, significantly reducing the energy consumption of crude oil dehydration.

[0035] The organic Rankine cycle system also includes an organic working fluid pump 9, the outlet side of the organic working fluid pump 9 is connected to the cold flow inlet side of the fourth heat exchanger 10, the cold flow outlet side of the fourth heat exchanger 10 is connected to the inlet side of the organic Rankine turbine expander 11, the outlet side of the organic Rankine turbine expander 11 is connected to the hot flow inlet side of the first heat exchanger 2, and the hot flow outlet side of the first heat exchanger 2 is connected to the inlet side of the organic working fluid pump 9. The electric energy generated by the organic Rankine turbine expander 11 is supplied to the dehydrator power supply 8; after being pressurized by the organic working fluid pump 9, the organic working fluid is heated and vaporized by the molten salt in the fourth heat exchanger 10, enters the organic Rankine turbine expander 11 to expand and generate electricity, and then the organic working fluid exhaust gas is cooled and liquefied by the crude oil emulsion in the first heat exchanger 2 and enters the next cycle. The electric energy generated by the organic Rankine turbine expander 11 is also supplied to the dehydrator power supply 8, ensuring the continuous and efficient separation of oil and water in the horizontal electric dehydrator 3, completing the organic Rankine cycle.

[0036] The concentrating solar thermal collection cycle system also includes a heliostat 14, which absorbs sunlight and transfers heat to a heat absorber 13. The working fluid outlet side of the heat absorber 13 is connected to the heat flow inlet side of the second heat exchanger 5, the heat flow outlet side of the second heat exchanger 5 is connected to the heat flow inlet side of the fourth heat exchanger 10, the heat flow outlet side of the fourth heat exchanger 10 is connected to the working fluid inlet side of the molten salt pump 12, and the working fluid outlet side of the molten salt pump 12 is connected to the working fluid inlet side of the heat absorber 13. A low-focusing concentrating solar collector is used to convert solar radiation into medium- and low-temperature thermal energy, which serves as a direct heat source for water vapor expansion and the organic Rankine cycle, and indirectly provides heat energy for preheating of the crude oil emulsion, thereby realizing cascade utilization of solar energy.

[0037] The working fluid in the organic Rankine cycle system is any one of the commonly used organic working fluids, including but not limited to R245fa pentafluoropropane, R365mfc pentafluorobutane, n-Nonane, n-Octane or n-Pentane.

[0038] The working fluid in the concentrated solar thermal collection cycle system is any one of the commonly used high-temperature resistant molten salts, including but not limited to NaNO3 sodium nitrate, K2CO3 potassium carbonate, LiF lithium fluoride or CaCl2 calcium chloride.

[0039] The working method of the present invention is as follows:

[0040] The crude oil emulsion extracted from the oil well is pressurized and transported to the first heat exchanger 2 by the crude oil emulsion pump 1, and is heated by the organic working medium exhaust gas released by the organic Rankine turbine expander 11 in the first heat exchanger 2. The viscosity of the heated crude oil emulsion and the strength of the oil-water interface film are reduced. The crude oil emulsion then enters the horizontal electric dehydrator 3 through the liquid inlet I for oil-water separation, completing the preheating and oil-water separation process; the oily wastewater separated from the crude oil emulsion is discharged from the water outlet III of the horizontal electric dehydrator 3, and after the flow and pressure are adjusted by the throttle valve 4, it enters the second heat exchanger 5 to be heated by the high-temperature molten salt and vaporized into water vapor. The high-temperature and high-pressure water vapor then enters the steam turbine expander 6 to expand and generate power. After the power generation process is completed, the water vapor exhaust gas exchanges heat with the dehydrated crude oil discharged from the oil outlet II in the third heat exchanger 7. The water vapor is cooled and liquefied and transported to the sewage treatment station, while the dehydrated crude oil is further heated to reduce viscosity and passed into the crude oil gathering and transportation pipeline network. The oily wastewater generated by the steam turbine expander 6 The generated electrical energy is directly supplied to the dehydrator power supply 8, ensuring the continuous and efficient operation of the horizontal electric dehydrator 3 and completing the direct expansion process of water vapor. After being pressurized by the organic working fluid pump 9, the organic working fluid is heated and vaporized by the molten salt in the fourth heat exchanger 10, and then enters the organic Rankine turbine expander 11 to expand and generate power. After completing the power generation process, the organic working fluid exhaust gas is cooled and liquefied by the crude oil emulsion in the first heat exchanger 2 and enters the next cycle. The electrical energy generated by the organic Rankine turbine expander 11 is also supplied to the dehydrator power supply 8, ensuring the continuous and efficient separation of oil and water in the horizontal electric dehydrator 3 and completing the organic Rankine cycle. The heliostat 14 absorbs sunlight and converts it into heat, which is transferred to the heat absorber 13. After absorbing heat from the solar heat absorber 13, the high-temperature resistant molten salt heats the oily wastewater and the organic working fluid through the second heat exchanger 5 and the fourth heat exchanger 10 respectively. The molten salt after heat loss is transported to the heat absorber 13 by the molten salt pump 12, completing the concentrated solar heat collection cycle.

[0041] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A crude oil electric dehydration system using solar energy, characterized in that: Including preheating and oil-water separation system, water vapor direct expansion system, organic Rankine cycle system, concentrated solar thermal collection cycle system; The concentrating solar thermal collection cycle system includes a second heat exchanger and a fourth heat exchanger, and the concentrating solar thermal collection cycle system exchanges heat with the organic Rankine cycle system through the fourth heat exchanger; the organic Rankine cycle system includes a first heat exchanger and an organic Rankine turbine expander; the organic Rankine cycle system transfers heat to the preheating and oil-water separation system through the first heat exchanger; The concentrated solar thermal cycle system exchanges heat with the water vapor direct expansion system through the second heat exchanger; the water vapor direct expansion system includes a dehydrator power supply and a steam turbine expander; the electrical energy generated by the organic Rankine turbine expander and the steam turbine expander is supplied to the dehydrator power supply to electrically dehydrate the crude oil; The preheating and oil-water separation system includes a crude oil emulsion pump, the working fluid outlet side of the crude oil emulsion pump is connected to the cold flow inlet side of the first heat exchanger, and the cold flow outlet side of the first heat exchanger is connected to the liquid inlet of the horizontal electric dehydrator; The steam direct expansion system includes a horizontal electric dehydrator, wherein the water outlet of the horizontal electric dehydrator is connected to the inlet side of the throttle valve, the outlet side of the throttle valve is connected to the cold flow inlet side of the second heat exchanger, the cold flow outlet side of the second heat exchanger is connected to the inlet side of the steam turbine expander, the outlet side of the steam turbine expander is connected to the hot flow inlet side of the third heat exchanger, and the oil outlet II of the horizontal electric dehydrator is connected to the cold flow inlet side of the third heat exchanger; the cold flow outlet side of the third heat exchanger is connected to the crude oil gathering and transportation network; The organic Rankine cycle system includes an organic working fluid pump, the outlet side of the organic working fluid pump is connected to the cold flow inlet side of the fourth heat exchanger, the cold flow outlet side of the fourth heat exchanger is connected to the inlet side of the organic Rankine turbine expander, the outlet side of the organic Rankine turbine expander is connected to the hot flow inlet side of the first heat exchanger, and the hot flow outlet side of the first heat exchanger is connected to the inlet side of the organic working fluid pump; The concentrating solar thermal collection cycle system includes a heliostat, which absorbs sunlight and transfers heat to a heat absorber. The working fluid outlet side of the heat absorber is connected to the heat flow inlet side of the second heat exchanger, the heat flow outlet side of the second heat exchanger is connected to the heat flow inlet side of the fourth heat exchanger, the heat flow outlet side of the fourth heat exchanger is connected to the working fluid inlet side of the molten salt pump, and the working fluid outlet side of the molten salt pump is connected to the working fluid inlet side of the heat absorber.

2. The crude oil electric dehydration system using solar energy according to claim 1, characterized in that: The working fluid at the working fluid inlet side of the crude oil emulsion pump is crude oil emulsion, and its water content by mass fraction is not greater than 30%.

3. The crude oil electric dehydration system using solar energy according to claim 1, characterized in that: The working medium of the oil outlet II of the horizontal electric dehydrator is dehydrated crude oil, and the water content thereof is less than or equal to 0.5% by mass.

4. The crude oil electric dehydration system using solar energy according to claim 1, characterized in that: The working medium of the water outlet III of the horizontal electric dehydrator is oily wastewater, and the oil content thereof is not greater than 1000 mg / L.

5. The crude oil electric dehydration system using solar energy according to claim 1, characterized in that: The hot flow outlet side of the third heat exchanger is connected to a sewage treatment station.

6. The operating method of the crude oil electric dehydration system using solar energy according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Using solar energy to heat the molten salt in the solar thermal collection circulation system; S2: After being pressurized by the organic working fluid pump, the organic working fluid is heated and vaporized by the molten salt in the fourth heat exchanger, and then enters the organic Rankine turbine expander to expand and generate power. After completing the power generation process, the organic working fluid exhaust gas is used to preheat the crude oil emulsion in the first heat exchanger; S3: preheating the crude oil emulsion through the first heat exchanger, and supplying the electric energy obtained by the organic Rankine turbine expander to the horizontal electric dehydrator to separate the preheated crude oil emulsion into oil and water; S4: The oily wastewater separated from the crude oil emulsion is gasified into water vapor by high-temperature molten salt in the second heat exchanger. The water vapor enters the steam turbine expander to expand and generate electricity, and the obtained electricity is supplied to the horizontal electric dehydrator to achieve oil-water separation in the crude oil emulsion through electric heating.

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