RU2780854C1 - Electric coalescing pipe apparatus - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: invention relates to the petroleum industry and can be used in petroleum preparation processes at enterprises of the petroleum industry. Electric coalescing pipe apparatus comprises a chamber with emulsion inlet branch pipes and an outlet pipe for the separated phases of the emulsion, and electrodes; wherein one electrode is central, and the other electrodes are positioned symmetrically relative to each other. At the ends, the chamber is additionally equipped with fluoroplastic bushing insulators whereto electrodes are attached; and high-voltage power sources are connected to the fluoroplastic insulators by connecting cables on the outside of the chamber. The symmetrical electrodes in the chamber are positioned in a fan-shaped arrangement relative to the central electrode. The apparatus constitutes an electric coalescing pipe apparatus of a linear configuration, wherein the flow of fluid in the chamber of said apparatus is subjected to the effect of reducing intensity of the rotating electric field. A model of a multielectrode system is implemented in the electric coalescing pipe apparatus: a central electrode ensuring the creation of a unidirectional electric field, and three electrodes in a radial fan-shaped arrangement along the chamber axis provided to create a spatially non-uniform field with reducing intensity in the direction of the emulsion flow. Two high-voltage power sources are applied in order to power the electrodes: a single-phase transformer for powering the central electrode and a three-phase transformer for creating the rotating electric field.

EFFECT: ensured process of effective separation of the water-in-oil emulsion in an electric coagulating pipe apparatus.

2 cl, 3 dwg

Description

The invention relates to the oil industry, can be used for oil preparation processes in the oil industry.

In the process of oil production, the well fluid, which is a mixture of oil, water, gas and suspended solids, usually comes to the day surface. Due to the relatively large difference in specific gravity, the separation of the gas and solid phases from the liquid phase does not cause serious technological and structural difficulties. Of particular difficulty in oil treatment technology are the processes of separating an oil-water emulsion into two liquid phases (oil / water), and bringing the residual content of the mass fraction of formation water in oil to the categorical standards of the quality standard. In addition to separators, settling tanks and heat exchangers, field oil treatment equipment includes electric dehydrators designed to break emulsions. The essence of field electrical emulsion processing is that in flooded oil placed in an alternating current electric field, there is a continuous movement of water droplets, as a result, the shells of these droplets are destroyed, they enlarge and separate from the oil. Traditional electric dehydrators are large-capacity settling vessels with plates of potential high-voltage electrodes placed in them. In modern conditions, there is a need to carry out the separation of water-oil emulsions in devices that are more compact than traditional ones, and in a faster mode in a fluid stream.

Known inclined tube electric dehydrator (SU573169 A1, IPC B01D 17/06, C10G 33/02, publ. A tubular high-potential electrode is concentrically installed in the body, on the outer surface of which pins are placed in a checkerboard pattern with a height increasing towards the oil outlet pipe. The water-oil emulsion entering the inlet pipe passes in a uniform alternating current electric field that occurs between concentrically located electrodes. As the flow moves to the oil outlet pipe located in the upper part of the inclined body, under the action of an inhomogeneous alternating current electric field, the intensity of which increases, the emulsion separates.

Known electrocoalescing apparatus for processing water-in-oil emulsion (SU1233902 A1, IPC B01D 17/06, C10G 33/02, publ. , which contributes to a higher inhomogeneity of the electric field. In order to increase the efficiency of the process of coalescence of water droplets in the initial section of the emulsion processing in the zone of increased electric field intensity, a branch pipe is installed coaxially to the body, expanding along the emulsion. The proposed design solution makes it possible to create a fluid flow with a more uniform velocity field along the cross section of the branch pipe. The disadvantages of this device are the uncontrolled coalescence of water droplets in the linear electric field of the central electrode and the formation of chains of coagulated drops, which leads to local breakdowns and short circuits.

A known apparatus for the destruction of an oil emulsion (SU1105213 A1, IPC B01D 17/06, publ. 07/30/1984) includes a vertical cylindrical body with nozzles for inlet and outlet of the emulsion, which is an external grounded electrode, and a central coaxial electrode made in the form of alternating sections of metal and hydrophobic dielectric. The central electrode is equipped with capacitors connecting each subsequent metal section with each previous section, the lowermost metal section of the central electrode is made in the form of a perforated disk isolated from the body. A horizontally perforated disc electrode is installed in the lower part of the housing in the area of the emulsion outlet pipe. In the circuit of each subsequent (from top to bottom) section of the central electrode, there is one more capacitor than in the previous circuit. The division of the central electrode into a number of sections leads to the formation of separate rather small areas of concentration of gradually decreasing electric field strength, in each of which coalescence processes occur independently of each other, the size of water droplets in the emulsion. The disadvantages of this apparatus include, affecting the reliability, the complexity of the design of the sectional central coaxial electrode with the connection of each section to a capacitor of a certain capacity, as well as a linearly directed field that affects the efficiency of dehydration.

Known electric dehydrator (SU1586741 A1, IPC B01D 17/06, publ. 08/23/1990), including a dielectric housing with a distribution head for supplying an emulsion and nozzles for removing oil and water, electrodes located around the circumference of the housing, a frequency-controlled source of three-phase voltage, input which is connected to the output of the conductivity meter. The output of the frequency-controlled three-phase voltage source is connected through a high-voltage transformer to the electrodes, and the connection is made in such a way that the applied alternating voltage, phase shifted by 120°, generates a rotating electric field, which increases the efficiency of the demulsification process. The supply of the electric dehydrator with a frequency-controlled three-phase voltage source, the input of which is connected to the emulsion conductivity meter, and the output to a high-voltage transformer, allows you to adjust the electric field strength and prevent the occurrence of a short circuit between the electrodes due to a change in the rotation speed of the intensity vector. The disadvantage of this electric dehydrator is that the housing is made of dielectric materials and the unreliability of the control system of the high-voltage voltage source, depending on the emulsion conductivity generator, in which the comparator element must output a signal to a frequency-controlled three-phase voltage source to change the voltage frequency and the rotation speed of the intensity vector.

A device for in-line demulsification of oil (SU1530202 A1, IPC B01D 17/06 publ. 12/23/1989) includes a pipeline section, piezoceramic elements, mesh electrodes installed between the piezoceramic elements and electrically connected to their metallized electrodes, a cylindrical dielectric gasket and a vibrator, acoustically coupled with piezoceramic elements. The water-oil emulsion, getting into the interelectrode space formed by the grid electrodes, is subjected to repeated action of an alternating electric field created by piezoceramic elements under the influence of mechanical vibrations on them. Mechanical vibrations arise due to the operation of a mechanical vibrator, acoustically coupled with piezoceramic elements. During the operation of the vibrator, an acoustic field also arises, the combined effect of the electric and acoustic fields intensifies the coalescence of water droplets. Under the action of mechanical stresses on metallized surfaces (electrodes), piezoceramic elements, opposite electric charges arise, creating a voltage of 5-20 kV on the grid electrodes, causing intense coalescence of water-oil emulsion droplets. The proposed device allows you to abandon the step-up transformer, lead wires and bushings, which reduces the material consumption of the device and the loss of electricity. However, the widespread use of this device is hampered by the following disadvantages:

- a complex system of arrangement of piezoceramic elements on those in contact with grid electrodes and other metallized electrodes, so that similar charges arise under mechanical influences;

- low reliability of a cylindrical gasket made of a dielectric plate material and under the constant influence of elastic wave vibrations;

- uncontrolled acoustic impact causes the effect of cavitation, which leads to the opposite phenomenon of coalescence

- dispersion of water droplets;

- expensive piezoceramic elements are used in the device;

- a structure assembled from dissimilar elements requires constant maintenance, because the stable mode of operation of the wave generator is carried out only with the "rigidity" of all connections.

A known apparatus for breaking oil emulsions (SU1105214 A, IPC B01D 17/06 publ. capacitors, while the capacitor of the upper ring is grounded, characterized in that, in order to intensify the process and increase the efficiency and reliability of the apparatus, the rings of the external electrode are made with a height increasing towards the emulsion output pipe, while the apparatus is equipped with additional capacitors connecting the free terminals of the capacitors of neighboring rings. The unbroken emulsion enters through a branch pipe at the top of the apparatus, where it is processed in an electric field between the central and outer electrodes, and is discharged through the lower branch pipe. To create a variable field strength, capacitors are connected to the outer annular electrode; as it moves from top to bottom, the emulsion sequentially enters the electric field with a gradually decreasing strength. This device has the following main disadvantages: - to supply a large number of potential electrodes inside the device, it is necessary to ensure the tightness of their connection through the wall with external high-voltage devices, which complicates the design and reduces its reliability; - the electric field in the apparatus is spatially oriented along one line in the vertical direction, the movement of coagulated water droplets in a rectilinear flow limits the intensity of electrocoalescence.

The closest in technical essence to the claimed invention is an electrostatic coagulator with a resonant tracking circuit (patent RU2567251 C2, IPC B03C 3/68 publ.10.11.2015). The electrostatic coalescer includes an outer wall defining a fluid flow path. A plurality of electrode plates are located within the flow path. The controller includes an inductor and a signal generator. The inductor is connected in parallel with a plurality of electrode plates. An inductor and a plurality of electrode plates define a resonant circuit. The signal generator is connected to the plurality of electrode plates and configured to apply an AC signal to the plurality of electrode plates at a frequency corresponding to the resonant frequency of the resonant circuit in the presence of process fluid. The invention generally relates to the separation of fluids in a process stream, and more particularly to an electrostatic coalescer with a resonant tracking circuit. The electrostatic field generated by the electrode plates polarizes the liquid droplets in the process stream. The main disadvantages of the invention include:

- low reliability of the design due to a set of many parallel electrode plates covered with an insulating material in the separation chamber;

- resonance does not provide stabilization of the voltage on the electrodes, which leads to the risks of increasing the dispersion of water and going beyond the limiting values of the electrical strength of the system elements;

- lack of physical justification for the equality of the resonance frequency with the optimal frequency of electrocoalescence, since the resonance is largely affected by both the geometry of the electrodes and the dielectric properties of the emulsion;

- a complex control system for the resonant circuit of the signal generator in providing control to prevent the formation of continuous chains (streams) of coagulated water between multiple plates, which leads to local breakdowns.

The purpose of the invention, as a technical solution, is to create a device that ensures the process of efficient dehydration of oil in a linearly arranged small-sized tubular electrocoalescer.

This task is achieved by the claimed tubular electrocoalescing apparatus, containing a chamber with emulsion inlet pipes and an outlet pipe for separated emulsion phases and electrodes, with one electrode being central, the rest being symmetrical relative to each other. Additionally, from the ends the chamber is equipped with fluoroplastic bushing insulators, to which the electrodes are attached, and from the outer side of the chamber, high-voltage power sources are connected to the fluoroplastic insulators by means of connecting cables.

Symmetrical electrodes inside the chamber are fan-shaped relative to the central electrode.

The proposed device is a linearly arranged tubular electro-coalescing apparatus, in the chamber of which, on the flow of a fluid medium, the effect of a decreasing intensity of a rotating electric field is created. A model of a multi-electrode system is implemented in a tubular electro-coalescing apparatus: a central electrode that provides the creation of a unidirectional electric field, and three electrodes with a radial fan-shaped arrangement along the chamber axis to form a spatially uneven field with a decreasing strength in the direction of the emulsion flow. To power the electrodes, two high-voltage sources were used: a single-phase transformer for powering the central electrode, and a three-phase transformer for creating a rotating electric field. EFFECT: invention makes it possible to carry out the process of efficient separation of an oil-water emulsion in a tubular electrocoagulating apparatus. In the claimed electrocoalescing tube apparatus, a model of a multi-electrode system is implemented with the option of placing electrodes according to a five-potential scheme:

- to create a unidirectional electric field, a central electrode is used, placed along the longitudinal axis inside the chamber, providing the necessary tension to intensify the coalescence process;

- to create a rotating electric field, three electrodes are used, located along the axis of the chamber in the form of a diverging fan, attached at an angle to the central electrode and, accordingly, to the body, figuratively representing a cone.

The essence of the invention is illustrated in Fig. 1, Fig. 2, Fig. 3.

Figure 1 schematically shows a section of the camera tubular electrocoalescing apparatus, where: 1 - camera; 2 - emulsion inlet pipe; 3 - branch pipe for the outlet of the separated phases of the emulsion; 4 - central electrode (F); 5 - symmetrical electrodes (ABC); 6 - fluoroplastic bushings.

On FIG. 2 shows the electrical circuit of the device, where 1 is a camera; 4 - central electrode (F); 5 - symmetrical electrodes (ABC); 7 - single-phase transformer (TP1); 8 - three-phase transformer (TP2).

On FIG. 3 schematically shows a fan-shaped arrangement of symmetrical electrodes.

The tubular electrocoalescing apparatus contains a chamber 1 in the form of a pipe segment having plugs at both ends. Fluoroplastic insulators 6 are mounted in the plugs of the chamber, providing fastening of electrodes 4(F) and 5 (ABC) to them inside the chamber, from the outside of the chamber 1 to the fluoroplastic insulators 6, by means of connecting cables, high-voltage power sources are connected: single-phase transformer 7 (TP1) connected to the central electrode 4 (F), each winding of the three-phase transformer 8 (TP2) is connected to one of the three symmetrical electrodes 5 (ABC). The transformers are equipped with taps in the primary and secondary windings to enable a discrete change in their output voltage, ensuring the adjustment of the electric field modes to the physicochemical properties of the emulsions in order to obtain the maximum separation effect.

Electrodes 4 (F) and 5 (ABC) are placed along the longitudinal axis inside the chamber, and three symmetrical electrodes 5 (ABC) are arranged in the form of a diverging fan, attached at an angle to the central electrode and, accordingly, to the body, figuratively representing a "cone" in the center along the axis of this "cone" is the central electrode 4 (F). To connect the device to the field pipeline system and ensure fluid circulation through the chamber on its shell, on opposite sides in the area of the ends, branch pipes are mounted: branch pipe 2 for the emulsion inlet, branch pipe 3 for the output of the separated phases of the emulsion.

The operation of the device is as follows.

Water-oil emulsion through the inlet pipe 2 enters the beginning of the chamber 1, where the "top" of all four electrodes is concentrated, in this zone a high-tension electric field is created. Getting into the zone of a powerful electric field, small drops of water begin to approach each other, colliding, unite into larger drops, forming dipoles. As the emulsion moves along the chamber, the distance between the symmetrical electrodes (ABC) increases (“the fan moves apart”), the field strength gradually weakens, preventing the destruction (dispersion) of large drops formed, while the rotating field prevents the formation of continuous streams from chains of large drops, leading to to local breakdowns between electrodes. Reaching the end of the chamber, the flow of the mixture with large drops of water exits through the nozzle 3 into the pipeline system for further processing.

In the claimed device, to increase the efficiency of the destruction of the emulsion (reducing the degree of its dispersion), the process of coalescence of water droplets in oil is intensified by exposing the emulsion to an electric field with the direction of the field strength vector intensively changing in time (conditionally "rotating" electric field). The fluid flow is affected by decreasing electric field strength along the length of the chamber. A rotating electric field drives the dipoles of water droplets in a limited tube space, while the number of drop collisions per unit time increases and, at the same time, the probability of formation of continuous conduction chains from electrode to electrode, leading to local breakdowns, is significantly reduced, which makes it possible to increase operating voltages on the electrodes and thereby intensify the coalescence process. The expandable 3-electrode system, in the direction of the flow inside the chamber, reduces the tension to a level below the critical level for the largest droplets, preventing the destruction of the large droplets formed. A rotating electric field leads to an increase in droplet collisions, an increase in the temperature of their near-surface layer, and merging into larger ones; elongation of the droplets and their rotation, provides a reduction in the frequency of local breakdowns (and the risk of sustained breakdown) in comparison with a unidirectional field.

In the claimed device, for the purpose of alternating the modes of formation of conduction chains based on the predominance of small drops due to high tension, a variant of "pumping" voltage with pulsed modulation of the rotating field is used.

At least two high-voltage power sources are used to power the chamber of the inventive tubular electrocoalescing apparatus:

- single-phase DC/AC (switching) voltage transformer 100 kV, power 8 kW;

- three-phase AC voltage transformer 10 kV, power 13 kW.

To implement an adaptive control mode for the electrocoalescence process of a fluid flow, a control program has been developed that makes it possible to control the number and size of water droplets according to the following indirect indicators:

- breakdown voltage of the emulsion;

- dielectric constant of the emulsion;

- intensity of short-term breakdowns;

- resonant frequencies of the electrode system;

- bandwidth and position of the frequency spectrum of the resonance of the electrode system;

- optical density of the emulsion in the visible region of the optical range and

infrared area.

The claimed device will allow to carry out the process of electrodehydrolysis of an oil emulsion as part of mobile block oil treatment plants in the fields in early production technologies and other modular small-sized complexes.

Claims (2)

1. A tubular electrocoalescing apparatus containing a chamber with emulsion inlet pipes and an outlet pipe for separated emulsion phases, electrodes, power sources, characterized in that one electrode is central, the rest are arranged symmetrically relative to each other in the form of a divergent "fan", additionally from the ends of the chamber equipped with fluoroplastic bushings to which the electrodes are attached, and from the outside of the chamber, high-voltage power sources are connected to the fluoroplastic insulators by means of connecting cables. 2. Pipe electric coalescer according to claim 1, characterized in that at least two high-voltage power sources are used as a power source: a single-phase AC/DC voltage transformer and a three-phase AC voltage transformer.

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