CN114958411A

CN114958411A - Crude oil electric desalting and dewatering equipment

Info

Publication number: CN114958411A
Application number: CN202210592379.4A
Authority: CN
Inventors: 蒋馨仪; 刘祖虎; 蒋剑云
Original assignee: Nanjing Willand Energy Technology Co ltd
Current assignee: Nanjing Willand Energy Technology Co ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-08-30

Abstract

The invention discloses crude oil electric desalting and dewatering equipment, which belongs to the field of crude oil electric desalting and dewatering, and comprises a mixing facility, an ultrasonic auxiliary demulsification facility, a pulse power supply, a multi-electric field electric desalting and dewatering tank, a circulating water injection system, a PLC (programmable logic controller) control system, other supporting equipment, instruments, pipelines and other facilities; the mixing facility comprises a static mixer and a mixing valve and is used for fully mixing the crude oil emulsion, the injected purified water, the injected demulsifier, the injected demetallizer and the like so as to lay a foundation for the next demulsification; the ultrasonic auxiliary demulsification facility comprises an oscillator, a vibration exciter, a power amplifier and an energy converter, and is used for converting an input power supply into ultrasonic input crude oil emulsion with certain frequency and demulsifying the emulsion; the ultrasonic demulsifier can improve the action efficiency of the demulsifier, reduce the dosage of the demulsifier and simultaneously realize the intellectualization of control and the energy conservation of a system through the synergistic action of ultrasonic waves and the demulsifier.

Description

Crude oil electric desalting and dewatering equipment

Technical Field

The invention relates to the field of crude oil electric desalting and dewatering, in particular to crude oil electric desalting and dewatering equipment.

Background

The crude oil electric desalting and dewatering equipment is important equipment for oil refining and petrochemical enterprises, and is an effective guarantee for reducing scaling and corrosion of the petrochemical equipment and preventing catalyst poisoning. The operation effect of the electric desalting and dewatering equipment relates to the stable operation, safe production and economic benefit of the whole plant device of petrochemical and oil refining enterprises. As the indexes of crude oil after the salt and water containing dehydration are increasingly strict at present, new desalting and dehydrating technologies are urgently needed to be developed to meet the industrial requirements, and ultrasonic enhanced demulsification, pulse power supply and optimization of internal parts of an electric desalting tank are representative technical means.

The electric desalting is a technological process of demulsifying crude oil emulsion by using electric field force to enable water drops to coalesce with each other and then settle, so that demulsification and coalescence are the two most critical factors in the electric desalting and dewatering process.

Ultrasonic wave intensified demulsification is a physical demulsification method, and the principle is that ultrasonic waves are used for radiating crude oil emulsion to generate ultrasonic effects (stirring, collision, aggregation, cavitation, heating, negative pressure and the like) to destroy an oil-water interface, and when a demulsifier is added or not added, demulsification of the emulsion is promoted.

The action mechanism of ultrasonic intensified demulsification is not exactly theoretically explained at present, and the following are relatively accepted:

1) the mechanical vibration of the ultrasonic wave causes the small water drops to displace, collide and coalesce to form larger water drops, so that the emulsifiers such as paraffin, colloid and asphalt in the crude oil are uniformly dispersed, the solubility of the emulsifiers is increased, and the mechanical strength of an oil-water interface is reduced;

2) the cavitation effect of the ultrasonic wave generates strong impact force to break part of long-chain paraffin and asphaltene in the emulsion, so that the viscosity of the sump oil is reduced, and the friction resistance of water drops in the process of collision polymerization sedimentation is reduced;

3) when the ultrasonic frequency is consistent with the self-vibration frequency of the micro water drops, the resonance effect of the ultrasonic waves generates resonance, and the movement, collision and combination of the water drops are further intensified to generate water drops with larger diameters.

The influencing factors of ultrasonic-assisted demulsification comprise: ultrasonic sound intensity, frequency and action time.

The sound intensity is the energy per unit area per unit time that passes perpendicular to the direction of propagation of the ultrasound. The larger the sound intensity is, the larger the energy transmitted by the micro-droplet is, the higher the movement speed of the micro-droplet is, the higher the collision probability among the micro-droplets is, and the dewatering efficiency is improved. But when the sound intensity exceeds the cavitation threshold, the breaking effect of the micro-droplets is obviously increased, the oil-water emulsification is intensified, and the dehydration effect is reduced. The attenuation of the acoustic intensity is in direct proportion to the square of the acoustic frequency, the higher the ultrasonic frequency is, the faster the attenuation of the acoustic intensity is, the more uneven the demulsification sound field is, and the poorer the demulsification effect is. The action time liquid is also an important parameter influencing the demulsification effect of the ultrasonic waves. As the action time increases, the water content after dehydration decreases first and then increases slightly, indicating that there is an optimum value for the action time, not a simple linear relationship.

The pulse power supply can not generate the short circuit phenomenon between electrodes in the electric dehydration tank by controlling the pulse frequency and the duty ratio (namely the ratio of the pulse output time to the pulse period) while providing the high-voltage electric field power supply (the pulse high voltage can be in an intermittent period by selecting proper pulse frequency before the short circuit is formed, and the next pulse is applied at proper time, so that the harm caused by the short circuit can be avoided, the electric field intensity is always kept in a high state when the pulse is output), and the phenomenon that the electric field enables the liquid drops to be dispersed to form liquid drops with smaller particle size is not easy to occur.

The demulsification mechanism of the pulse electric field is that before the water drops in the crude oil are coalesced under the action of the electric field, the water drops are firstly arranged into chains, and a large amount of chains are generated in a desalting and dewatering tank to coalesce the water drops. These chains must not be too long, otherwise they generate conduction currents so that short circuits are formed leading to energy leakage; at the same time, the chain should not be too short, which is just long enough to allow the water droplets in the chain to coalesce under the applied force of the electric field. For a pulse electric field, at the optimal frequency, water drops are completely polarized at the peak value of the electric field, the force among the water drops is the largest, the mutual collision is the largest, the water drops are obviously coalesced, and therefore good dehydration efficiency is achieved.

The pulse electric field mainly influences the crude oil desalting and dewatering effects by three parameters of pulse amplitude, pulse width and pulse frequency.

The pulse amplitude refers to the peak value of the pulse voltage. When the electric field strength exceeds the tension of the water drops, the water drops are subjected to electric dispersion, and the electric desalting and dewatering effect is reduced. Pulse width also has an effect on coalescence. The pulse width is too small, the dehydration energy is too low, the coalescence action force among water drops is small, and the coalescence effect is poor; the pulse width is too large, the electric energy is easy to be lost through the water chain, so that the electric dehydration energy consumption is increased, the dehydration effect is also influenced, and the pulse width has an optimal range. The water drop in the electric field is in a state of continuous vibration, and when the pulse frequency is close to the vibration frequency of the water drop, resonance is generated. Under the action of resonance, the mechanical strength of the oil-water interface film is greatly weakened, the interface film is easy to break, and the water drop coalescence effect is good. The weak pulse frequency is too low or too high, which can inhibit the coalescence of water drops and reduce the efficiency of the electric desalting and dewatering.

Since the 90 s of the last century, the american petroleum jelly company developed a high-speed electric desalting technology by changing the internal configuration of electrode plates, the multi-electric field design in the electric desalting tank received attention from the industry, and how to improve the crude oil treatment capacity and treatment efficiency of a single tank by a better internal part design and a matching process became an important technical direction of electric desalting design.

Disclosure of Invention

1. Technical problem to be solved

Aiming at the problems in the prior art, the invention aims to provide crude oil electric desalting and dewatering equipment which can improve the action efficiency of a demulsifier and reduce the using amount of the demulsifier through the synergistic action of ultrasonic waves and the demulsifier, and simultaneously realize the intellectualization of control and the energy conservation of a system.

2. Technical scheme

In order to solve the above problems, the present invention adopts the following technical solutions.

An electric desalting and dewatering device for crude oil, comprising:

the mixing facility comprises a static mixer and a mixing valve and is used for fully mixing the crude oil emulsion, the injected purified water, the injected demulsifier, the injected demetallizing agent and the like so as to lay a foundation for the next demulsification;

the ultrasonic auxiliary demulsification facility comprises an oscillator, a vibration exciter, a power amplifier and an energy converter, and is used for converting an input power supply into ultrasonic input crude oil emulsion with certain frequency, demulsifying the emulsion, improving the demulsification effect of the emulsion and realizing the purpose of using no or less demulsifier;

the pulse power supply comprises a silicon controlled trigger and a transformer and is used for boosting a low-voltage power supply into a high-voltage pulse power supply;

the electric desalting and dewatering tank is a metal horizontal or vertical pressure container, and a specially designed multi-electric field internal part is contained in the electric desalting and dewatering tank and used for introducing high voltage electricity generated by a pulse power supply into the electric desalting and dewatering tank to form a high voltage electric field so as to facilitate coalescence and sedimentation of micro water drops in crude oil emulsion;

the circulating water injection system comprises a water injection pump, a circulating water injection pump, a matched regulating valve and a flowmeter and is used for injecting water and circulating water to the crude oil emulsion;

the PLC control system comprises a power distribution cabinet, a wiring cabinet and a control program, and is used for collecting all instrument signals from the electric desalting and dewatering system and automatically executing relevant process operation according to a set control logic program;

other supporting equipment, instruments, pipelines and other facilities at least comprise necessary instruments, pipelines and supporting equipment which are required by the process in the electric desalting and dewatering system and are used for realizing the operation of the whole electric desalting and dewatering system.

Furthermore, a lower electric field crude oil flow meter and an upper electric field crude oil flow regulating valve are arranged on an oil inlet pipeline at the lower part of the electric desalting and dewatering tank and used for regulating crude oil flow of an upper electric field and a lower electric field in the electric desalting and dewatering tank, and a lower electric field pulse power supply and an upper electric field pulse power supply are arranged at the top of the electric desalting and dewatering tank and respectively provide power for the upper electric field and the lower electric field in the electric desalting and dewatering tank and are used for forming a high-voltage pulse electric field.

Furthermore, the top of the electric desalting and dewatering tank is also provided with an oil-water boundary level instrument for indicating the oil-water boundary level inside the electric desalting and dewatering tank.

Furthermore, a plurality of transducers are arranged in the straight pipe section of the ultrasonic auxiliary demulsification facility, each transducer is provided with a relatively independent control facility, and the transducers are sequentially arranged inside the demulsification auxiliary demulsification facility.

Furthermore, the control mode of the pulse power supply is provided with automatic recovery, constant voltage operation, constant current mode and remote control.

Further, the equipment can be single-stage electric desalting and dewatering, can be two-stage electric desalting and dewatering, and can also be three-stage electric desalting and dewatering.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

the ultrasonic intensified demulsification has the following beneficial effects:

(1) the ultrasonic wave has good conductivity, so the ultrasonic wave is suitable for various types of emulsion;

(2) for the emulsion which is difficult to break due to complex chemical components and emulsification reasons such as oil-in-water emulsified crude oil of tertiary oil recovery, aged oil and the like, better emulsion breaking effect can be obtained by ultrasonic strengthening;

(3) the demulsification temperature and the energy consumption can be reduced;

(4) the ultrasonic wave and the demulsifier have synergistic effect, so that the action efficiency of the demulsifier can be improved, and the using amount of the demulsifier can be reduced.

The pulse electric field formed by the pulse power supply has the following beneficial effects:

(1) short circuit is avoided;

(2) the dehydration efficiency is improved;

(3) the power consumption is saved (the intermittent power supply mode shortens the power-on time);

(4) stable operation (microcomputer control, voltage compensation, and controlled output of pulse voltage by thyristor to effectively avoid voltage reduction due to current increase).

The advantage of multiple electric fields is that the same electric desalting and dewatering tank can be used for improving the crude oil treatment capacity or adapting to the heavy and poor oil products.

The control system has the advantages that all process parameter signals and control logic of the electric desalting and dewatering system can be integrated in one PLC, the electric desalting and dewatering system can be automatically controlled to operate, and control intellectualization and system energy conservation are achieved.

Drawings

FIG. 1 is a schematic diagram of the process flow structure of the system of the present invention;

fig. 2 is a schematic structural view of the ultrasonic wave generation principle of the present invention.

The numbering in the figures illustrates:

1. a first-stage static mixer; 2. a primary mixing valve; 3. a primary mixed differential pressure transmitter; 4. a first-stage ultrasonic auxiliary demulsification facility; 5. a primary lower electric field crude oil flowmeter; 6. a primary upper electric field crude oil flow regulating valve; 7. a first-stage electric desalting and dewatering tank; 8. a primary lower electric field pulse power supply; 9. a primary upper electric field pulse power supply; 10. a first-level oil-water level gauge; 11. a first-stage oil-water boundary level regulating valve; 12. a secondary static mixer; 13. a secondary mixing valve; 14. a secondary mixed differential pressure transmitter; 15. a secondary ultrasonic auxiliary demulsification facility; 16. a second-stage lower electric field crude oil flowmeter; 17. a two-stage upper electric field crude oil flow regulating valve; 18. a secondary electric desalting and dewatering tank; 19. a secondary lower electric field pulse power supply; 20. a secondary upper electric field pulse power supply; 21. a secondary oil-water level gauge; 22. a secondary oil-water interface level regulating valve; 23. a water injection pump; 24. a water injection/drainage heat exchanger; 25. a circulating water injection pump; 26. a secondary water injection flowmeter; 27. a secondary water injection flow regulating valve; 28. a first-stage water injection flowmeter; 29. a primary water injection flow regulating valve; 30. backwashing the water pump; 31. a first switch valve; 32. and a second switch valve.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

Example (b):

referring to fig. 1-2, a crude oil electric desalting and dewatering device has the following specific working procedures (two stages are taken as an example):

crude oil emulsion is mixed (with water, a demulsifier and a demetallizing agent) from the outside of the device through a primary static mixer 1 and a primary mixing valve 2 in sequence, a primary mixed differential pressure transmitter 3 indicates differential pressure in the mixing process, the fully mixed crude oil emulsion is subjected to ultrasonic demulsification through a primary ultrasonic auxiliary demulsification facility 4, the crude oil emulsion subjected to ultrasonic demulsification enters a primary electric desalting and dewatering tank 7 in two paths, wherein a primary lower electric field crude oil flowmeter 5 and a primary upper electric field crude oil flow regulating valve 6 are arranged on a lower oil inlet pipeline and are used for regulating the crude oil flow of an upper electric field and a lower electric field in the primary electric desalting and dewatering tank 7, a primary lower electric field pulse power supply 8 and a primary upper electric field pulse power supply 9 are arranged at the top of the primary electric desalting and dewatering tank 7 and respectively provide power for the upper electric field and the lower electric field in the primary electric desalting and dewatering tank 7, for forming a high voltage pulsed electric field. The top of the first-stage electric desalting and dewatering tank 7 is also provided with a first-stage oil-water boundary level instrument 10 for indicating the oil-water boundary level inside the first-stage electric desalting and dewatering tank 7. The salt-containing sewage formed after the coagulation, desalination and dehydration in the electric field is discharged out of the tank at the bottom of the first-stage electric desalting and dehydrating tank 7, and is sent to a water injection/drainage heat exchanger 24 after the liquid level is adjusted by a first-stage oil-water boundary level adjusting valve 11. Crude oil which is desalted and dehydrated by electric field coalescence leaves the first-stage electric desalting and dehydrating system from the top of the first-stage electric desalting and dehydrating tank 7 and then leaves the second-stage electric desalting and dehydrating system, the crude oil is mixed (with water, a demulsifier and a demetallizing agent) by sequentially passing through a second-stage static mixer 12 and a second-stage mixing valve 13, a second-stage mixed differential pressure transmitter 14 indicates the differential pressure in the mixing process, the fully mixed crude oil emulsion is subjected to ultrasonic demulsification by a second-stage ultrasonic auxiliary demulsification facility 15, the crude oil emulsion subjected to ultrasonic demulsification enters the second-stage electric desalting and dehydrating tank 18 in two ways, wherein a second-stage lower electric field crude oil flow meter 16 and a second-stage upper electric field crude oil flow regulating valve 17 are arranged on a lower oil inlet pipeline and are used for regulating the crude oil flow of an upper electric field and a lower electric field in the second-stage electric desalting and dehydrating tank 18, and a second-stage lower electric field pulse power supply 19 and a second-stage upper electric field pulse power supply 20 are arranged on the top of the second-stage electric desalting and dehydrating tank 18, power is respectively supplied to an upper electric field and a lower electric field inside the secondary electric desalting and dewatering tank 18 to form a high-voltage pulse electric field. The top of the second-stage electric desalting and dewatering tank 18 is also provided with a second-stage oil-water boundary level instrument 21 for indicating the oil-water boundary level inside the second-stage electric desalting and dewatering tank 18. The salt-containing sewage formed after the electric field coalescence desalination and dehydration is discharged out of the tank at the bottom of the second-stage electric desalination and dehydration tank 18, and is regulated by a second-stage oil-water boundary position regulating valve 22 before the first-stage electric desalination and dehydration mixing facility or is sent to a water injection/drainage heat exchanger 24. The crude oil desalted and dehydrated by the electric field coalescence leaves the secondary electric desalting and dehydrating system from the top of the secondary electric desalting and dehydrating tank 18 to be sent to a subsequent processing facility.

The water injection and circulating water injection system is operated as follows: purified water is pressurized by a water injection pump 23 from the outside of the device, then enters a water injection/drainage heat exchanger 24 to exchange heat with electric dewatering water from a primary electric desalting and dewatering tank 7, after the heat exchange reaches a certain temperature, the electric dewatering water enters a sewage treatment facility, and after the flow of the water after the heat exchange is regulated by a secondary water injection flow meter 26 and a secondary water injection flow regulating valve 27, the water is injected into the front of a secondary electric desalting and dewatering mixing facility at a specific flow. The secondary electric desalting and draining water is pressurized by a circulating water injection pump 25, then is subjected to flow regulation by a primary water injection flow meter 28 and a primary water injection flow regulating valve 29, and is injected into the primary electric desalting and dewatering mixing facility at a specific flow rate. Or the water injected by the water injection pump 23 can be directly injected into the first-stage electric desalting and dewatering mixing facility, at the moment, the water discharged from the circulating water injection pump 25 is regulated by the secondary oil-water interface regulating valve 22 and then directly enters the water injection/water discharge heat exchanger 24, and the purified water from the outside of the device is pressurized by the water injection pump 23, the water injection/drainage heat exchanger 24 exchanges heat with the electric desalting and drainage water from the first-stage electric desalting and dewatering tank 7 and the second-stage electric desalting and dewatering tank 18, after the heat exchange reaches a certain temperature, after the electric dehydration drainage water is sent to a sewage treatment facility, part of the water injection after heat exchange is adjusted in flow by a secondary water injection flow meter 26 and a secondary water injection flow adjusting valve 27, before being injected into the second-stage electric desalting and dewatering mixing facility at a specific flow rate, a part of the mixed solution is injected into the first-stage electric desalting and dewatering mixing facility at a specific flow rate after the flow rate of the mixed solution is adjusted by a first-stage water injection flow meter 28 and a first-stage water injection flow adjusting valve 29. When the water is circularly filled, the first switch valve 31 is opened, the second switch valve 32 is closed, when the water is not circularly filled, the first switch valve 31 is closed, the second switch valve 32 is opened, and simultaneously, the first-stage electric desalting and dewatering tank 7 and the second-stage electric desalting and dewatering tank 18 can be used, and the purified water is pressurized by the back washing water pump 30 from the outside of the device and enters the inside of the device to carry out back washing.

The working principle of the ultrasonic auxiliary demulsification facility is as follows: the ultrasonic auxiliary demulsification facility is a part of straight pipe section arranged behind the mixing facility and in front of the electric desalting and dewatering tank, and an ultrasonic transducer is arranged inside the straight pipe section. The ultrasonic generator converts alternating 220V voltage into an electric signal matched with the transducer, the electric signal passes through the power amplifier and then is subjected to impedance matching, and the transducer is driven to convert the electric signal into mechanical vibration, so that the conversion of electric energy and sound energy is realized. The transducer converts the electric energy output by the ultrasonic generator into mechanical energy and transmits the mechanical energy to the crude oil emulsion in a mechanical vibration mode, so that the emulsion generates a cavitation effect and ultrasonic-assisted emulsion breaking is realized.

The pulse power supply mainly comprises a pulse transformer and a control system, wherein the pulse transformer is used as main equipment and comprises a low-voltage explosion-proof junction box, a pulse transformer main body, an explosion-proof high-voltage junction box and the like. The input cable is connected into the pulse transformer through the low-voltage explosion-proof junction box and the isolation sealing wiring terminal, and is output after inversion, boosting and secondary rectification. The operation process of the pulse transformer comprises the following steps: the 380V power frequency alternating current power supply firstly rectifies and filters, and the silicon controlled rectifier is adopted for rectification, so that the effect of regulating and controlling voltage is achieved. The key of the pulse power supply is a resonant converter (inverter), which mainly comprises 4 high-power IGBTs (insulated gate bipolar transistors), an inductor and a capacitor, the principle of generating high frequency is similar to that of ultrasonic waves, and the resonance generated by the inverter is mainly realized by switching on and off the IGBTs, so that the adjustment and control of frequency, pulse width, pulse gap and duty ratio can be realized by switching on and off and interval time of a controller. The microcomputer controller is a pulse power supply control center with a CPU as a core. The microcomputer controller continuously monitors various parameters such as output voltage and output current of the pulse transformer through a detection circuit arranged in the pulse transformer, on one hand, the microcomputer controller is connected with an operator (HIM, IPC, DCS and the like) of a central control room through a PLC to monitor and set working voltage, working current, frequency, duty ratio and the like of a system, on the other hand, the microcomputer controller is connected with a rectification and voltage regulation system and an inversion control system, the operation characteristics and parameters of the system can be artificially controlled and regulated through a remote communication system, the operation of the pulse transformer can be automatically controlled according to preset programs and parameters, and meanwhile, fault diagnosis and alarm can be carried out.

PLC control system (including pulse power control center), it is used for adopting all instrument signals of electric desalting and dewatering system, controls the automatic operation of all electric desalting and dewatering systems, and is specific:

controlling the mixed differential pressure of the electric desalting and dewatering system: the primary electric desalting and dewatering system mixed differential pressure control loop is composed of a primary static mixer 1, a primary mixing valve 2 and a primary mixed differential pressure transmitter 3, generally, the set value of the mixed differential pressure of the electric desalting and dewatering system is 50kPa (the value can be adjusted and set in a PLC control system), when the measured value of the primary mixed differential pressure transmitter 3 is higher than the set value, the primary mixing valve 2 is adjusted to be opened until the mixed differential pressure reaches the set value; when the measured value of the primary mixed differential pressure transmitter 3 is lower than the set value, the primary mixing valve 2 is adjusted to be closed until the mixed differential pressure reaches the set value. The mixed differential pressure control loop of the secondary electric desalting and dehydrating system consists of a secondary static mixer 12, a secondary mixing valve 13 and a secondary mixed differential pressure transmitter 14, generally, the set value of the mixed differential pressure of the electric desalting and dehydrating system is 50kPa (the value can be adjusted and set in a PLC control system), and when the measured value of the secondary mixed differential pressure transmitter 14 is higher than the set value, the secondary mixing valve 13 is adjusted to be opened until the mixed differential pressure reaches the set value; when the measured value of the secondary mixed differential pressure transmitter 14 is lower than the set value, the secondary mixing valve 13 is adjusted to be closed until the mixed differential pressure reaches the set value.

Controlling the oil-water interface level of the electric desalting and dewatering system: the first-stage electric desalting and dewatering device oil-water boundary control loop is composed of a first-stage oil-water boundary instrument 10 and a first-stage oil-water boundary regulating valve 11, generally, the oil-water boundary setting value of the electric desalting and dewatering device is 70% (the value can be adjusted and set in a PLC control system), when the measured value of the first-stage oil-water boundary instrument 10 is higher than the setting value, the first-stage oil-water boundary regulating valve 11 is adjusted to be opened to be large until the oil-water boundary reaches the setting value; when the measured value of the primary oil-water level gauge 10 is lower than the set value, the primary oil-water level regulating valve 11 is regulated to be closed until the oil-water level reaches the set value. The oil-water boundary control loop of the secondary electric desalting dehydrator consists of a secondary oil-water boundary instrument 21 and a secondary oil-water boundary regulating valve 22, generally, the oil-water boundary set value of the electric desalting dehydrator is 70% (the value can be regulated and set in a PLC control system), and when the measured value of the secondary oil-water boundary instrument 21 is higher than the set value, the secondary oil-water boundary regulating valve 22 is regulated to be opened until the oil-water boundary reaches the set value; when the measured value of the secondary oil-water level gauge 21 is lower than the set value, the secondary oil-water level regulating valve 22 is regulated to be closed until the oil-water level reaches the set value.

Controlling the flow of crude oil in a lower electric field of the electric desalting and dewatering system: the primary electric desalting and dewatering system lower electric field crude oil flow control loop is composed of a primary lower electric field crude oil flow meter 5 and a primary upper electric field crude oil flow regulating valve 6, generally, the primary electric desalting and dewatering system lower electric field crude oil flow set value is 60% of the total flow (the value can be adjusted and set in the PLC control system), when the measured value of the primary lower electric field crude oil flow meter 5 is higher than the set value, the primary upper electric field crude oil flow regulating valve 6 is adjusted to be opened until the lower electric field crude oil flow reaches the set value; when the measured value of the primary lower electric field crude oil flowmeter 5 is lower than the set value, the primary upper electric field crude oil flow regulating valve 6 is regulated to close the lower electric field crude oil flow to reach the set value. The lower electric field crude oil flow control loop of the secondary electric desalting and dewatering system consists of a secondary lower electric field crude oil flow meter 16 and a secondary upper electric field crude oil flow regulating valve 17, generally, the set value of the lower electric field crude oil flow of the secondary electric desalting and dewatering system is 60% of the total flow (the value can be regulated and set in a PLC control system), and when the measured value of the secondary lower electric field crude oil flow meter 16 is higher than the set value, the secondary upper electric field crude oil flow regulating valve 17 is regulated to be opened until the lower electric field crude oil flow reaches the set value; when the measured value of the two-stage lower electric field crude oil flowmeter 16 is lower than the set value, the two-stage upper electric field crude oil flow regulating valve 17 is regulated to close the lower electric field crude oil flow to reach the set value.

The control of ultrasonic auxiliary demulsification is mainly used for controlling the sound intensity, frequency and action time of ultrasonic waves. The alternating current 220V voltage is converted into an electric signal matched with the transducer by changing the input power of the ultrasonic generator, and the electric signal passes through the power amplifier and then is subjected to impedance matching to drive the transducer to convert the electric signal into mechanical vibration, so that the conversion of electric energy and sound energy is realized. The transducer is provided with an electric energy storage element and a mechanical vibration system, an electric oscillation signal from a power supply output end causes the change of an electric field or a magnetic field of the electric energy storage element in the transducer, and the change of the electric field or the magnetic field generates a driving force on the mechanical vibration system of the transducer through certain effect to enable the mechanical vibration system to enter a vibration state, so that a medium in contact with the mechanical vibration system of the transducer is driven to vibrate, and ultrasonic waves are radiated into crude oil emulsion. For a specific crude oil variety, the adaptive power and sound intensity of the specific crude oil are determined according to the relationship between the input power (sound intensity) and the demulsification effect through a plurality of test trials. The ultrasonic auxiliary demulsification facility is characterized in that a plurality of transducers are arranged in a straight pipe section of the ultrasonic auxiliary demulsification facility, each transducer is provided with a relatively independent control facility, the plurality of transducers are sequentially arranged in the demulsification auxiliary demulsification facility, and the number of the transducers which simultaneously work in the straight pipe section is determined by controlling the on-off of a facility power supply so as to determine the time of ultrasonic auxiliary demulsification. The control and logic decision process described above is set up and implemented in the PLC.

The control mode of the pulse power supply is as follows:

short-circuit protection: when the system finds that the electric field current is too large and exceeds the set or rated current of the system, the CPU instructs the MTC module to reduce the voltage until the power supply is stopped.

1) Automatic recovery: and after the short-circuit state is eliminated, the system brake is recovered to the set voltage.

2) Constant pressure operation: in the actual production of electric desalting/water, oil and operation conditions are changed frequently, that is, the conductance of processed oil is changed frequently, and under the set voltage, as long as the operation current does not exceed the rated capacity of the pulse transformer, the system can keep the operation voltage unchanged, thereby realizing constant-voltage operation.

3) A constant current mode: in the actual production of electric desalting/water, oil and operation conditions are changed frequently, that is, the conductance of processed oil is changed frequently, and under the set current, the system can be operated according to the set current value, and the voltage can be automatically adjusted according to the current value.

4) Remote control: all the operation parameters can be set and monitored in the electric control room. DCS can be realized in a central control room.

The invention adopts the integrated process flow of 'ultrasonic demulsification + pulse power supply + multi-electric field' crude oil electric desalting and dewatering, which can be a single-stage flow, a two-stage flow and a three-stage flow, and compared with a two-stage electric desalting and dewatering system, the single-stage flow has no circulating water injection system; the tertiary flow is added with a tertiary drainage circulation reinjection secondary flow and a secondary drainage circulation reinjection primary flow.

The foregoing is only a preferred embodiment of the present invention; the scope of the invention is not limited thereto. Any person skilled in the art should also be able to cover the technical scope of the present invention by the equivalent or modified embodiments and the modified concepts of the present invention.

Claims

1. The utility model provides a crude oil electric desalting dewatering equipment which characterized in that includes:

2. The crude oil electric desalting and dewatering equipment according to claim 1, wherein: the electric desalting and dewatering tank is characterized in that a lower electric field crude oil flow meter and an upper electric field crude oil flow regulating valve are arranged on an oil inlet pipeline at the lower part of the electric desalting and dewatering tank and used for regulating crude oil flow of an upper electric field and a lower electric field in the electric desalting and dewatering tank, and a lower electric field pulse power supply and an upper electric field pulse power supply are arranged at the top of the electric desalting and dewatering tank and respectively supply power to the upper electric field and the lower electric field in the electric desalting and dewatering tank and used for forming a high-voltage pulse electric field.

3. The crude oil electric desalting and dewatering equipment according to claim 1, wherein: and the top of the electric desalting and dewatering tank is also provided with an oil-water boundary level instrument for indicating the oil-water boundary level inside the electric desalting and dewatering tank.

4. The crude oil electric desalting and dewatering equipment according to claim 1, wherein: the ultrasonic auxiliary demulsification facility is characterized in that a plurality of transducers are arranged in the straight pipe section of the ultrasonic auxiliary demulsification facility, each transducer is provided with a relatively independent control facility, and the plurality of transducers are sequentially arranged inside the demulsification auxiliary facility.

5. The crude oil electric desalting and dewatering equipment according to claim 1, wherein: the control mode of the pulse power supply is provided with automatic recovery, constant voltage operation, constant current mode and remote control.

6. The crude oil electric desalting and dewatering equipment according to claim 1, wherein: the equipment can be single-stage electric desalting and dewatering, two-stage electric desalting and dewatering, and three-stage electric desalting and dewatering.