GB2377397A

GB2377397A - Separating components of liquid/liquid emulsion using electrostatic force

Info

Publication number: GB2377397A
Application number: GB0117023A
Authority: GB
Inventors: Mojtaba Ghadiri; John Son Eow
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-12
Filing date: 2001-07-12
Publication date: 2003-01-15
Also published as: GB0117023D0

Abstract

The components of a liquid/liquid emulsion or dispersion (eg water in oil) are separated using an electrostatic force in combination with either a gravitational or hydrocyclonic force. The electrostatic field may be a pulsed unidirectional field applied between a high voltage electrode (cone 8) and a low voltage electrode (strip 15). Voltage and frequency ranges are given. In the electro-mechanical coalescer-separator shown, the dispersion enters through inlet tube 3. The water droplets in the dispersion will get charged between the metallic cone 8 and the metallic strip 15, between the cone 8 and the accumulated water layer at the bottom of container 23, and between the cone and its metallic support 19. The charged water droplets are attracted towards the accumulated water layer, which can be drained through outlet 5. The oil phase leaves though outlet 4. In Fig 6, not shown, the conical electrode 8 and the metallic strip 15 are longer and a swirling action is imparted to the dispersion causing separation by hydrocyclonic as well as electrostatic force. The containers in both embodiments are transparent to allow the separation process to be viewed.

Description

ELECTRO-MECHANICAL COALESCER-SEPARATORS FOR THE SEPARATION OF AQUEOUS-IN-OIL DISPERSIONS BACKGROUND OF THE INVENTIONS (a) Field of the Inventions The inventions presented here relate to the separation of any type of aqueous-in-oil dispersion. Generally the separation of water/oil dispersions or emulsions are highly desirable in various industries where certain quantity of aqueous phase can be present in the system, causing various problems to the equipment, as well as increasing the maintenance costs. Examples of this application are de-watering crude oil at the well head in crude oil drilling, dewatering distillate fuels in ships, solid-liquid and liquid-liquid extractions, and edible oil processing.

In the process of de-watering crude oil, the co-produced water, associated with raw crude oil as it emerges from the well, originates either from the oil producing reservoir and its associated aquifer or as a result of the injection of water into the reservoir for maintaining its internal pressure. This water is usually heavily salt-saturated and thus often termed as'brine'. Although brine constitutes a very small fraction of the well output initially, this could contribute a substantial amount of the flow in the later production stages. The decision to close down a well would often be decided by the costs of water removal operations. However, with the increasing value of oil, it is more likely that the wells will be kept on stream with progressively higher water contents. Also the turbulence generated by flow control devices such as flowmeters and pumps, as well as gas release from crude oil during production process, tends to cause emulsification with the aqueous component becoming finely dispersed in the continuous oil phase. Therefore effective separation of these liquids at the wellhead is important due to the need for efficient utility of transportation systems and to assist in the reduction of the potentially severe corrosion problem which can be

caused by hot brines. This is especially relevant in offshore production sites where field-to-refinery transfer costs are high and maintenance is difficult.

As mentioned earlier, one of the major applications of the inventions here is possibly also in the edible oil production industry. Generally, palm oil can be extracted from treated palm oil fruits by three different methods: centrifugation, hydraulic press and screw press. Using the first method produces 70-90% oil, 10-20% water and 1 - 4% solids; the second method produces 65-90% oil, 10- 30% water and 3-6% solids ; while screw press gives 40 - 75% oil, 10 - 40% water and 6-25% solids. The items of conventional equipment used to separate these different phases are decanters, centrifuges, gravity separators and vacuum dryers. These items of equipment generally have a high residence time and are consequently of considerable dimensions and weight. These are particularly unwelcome on platforms where space and deck loading are very limited.

It is therefore of high importance to develop systems that have a large throughput and low mean residence time. The inventions presented here relate to devices which effectively perform the same works described above, but in a different way. The inventions here have no moving parts and can be mounted in situ without any external mechanical connection, as well as can be operated at higher temperatures and pressures without encountering any major difficulty.

Furthermore, the capital and maintenance costs of the inventions are insignificant as compared to the costs of centrifuges or vacuum dryers. Moreover, the inventions in this patent have been designed in such a way as to reduce the space needed while maintaining, or even increasing, the separation efficiency. The separation efficiency, as used hereinafter, is the ratio between the aqueous phase volumetric flow rate into the inventions and the aqueous phase volumetric flow rate exiting from the inventions.

The present inventions are based upon the discovery that, depending on certain factors, an electrostatic field can be effectively applied to the flow of

aqueous-in-oil dispersions in such a way as to assist in the separation of the two different phases. These factors will be described hereinafter in detail.

The apparatuses presented here are highly effective for their purpose when small aqueous drops are dispersed in viscous oil continuous phase. Pure physical separation such as sedimentation, centrifugation and filtration have severe practical limitations in this application, such as long residence time, large space requirement and blocking of filter mediums. Therefore, by utilising the present inventions here, these major problems can be effectively reduced, or even eliminated altogether, especially when pulsed direct current (d. c. ) electric field and an optimum pulse frequency are applied in combination with physical separation effects generated by liquid flow in the invention.

Generally, the present inventions here consist two different combinations.

The first is the combination of the electrostatic force, due to the applied electric field, with gravitational force. The second combination is of the electrostatic force with hydrocyclonic forces due to the swirling motion of the flow within the invention. This is in line with current requirements to further optimise the separation equipment to accommodate higher throughput, lower operational costs and higher efficiency. This second combination has been found to be more applicable for higher flow rates of aqueous-in-oil dispersions, with the oil phase functioning as a dielectric medium to facilitate in creating an electrostatic field between two differently charged electrodes.

(b) Description of the Related Art As described earlier, the effective removal of the dispersed phase from the continuous phase in water-in-oil dispersions is crucial in many processes.

Currently there are several techniques available for this purpose such as chemical de-emulsification, pH adjustment, gravity or centrifugal settling, filtration, heat

treatment, membrane separation and electrostatic de-emulsification. There are advantages and disadvantages for each of these techniques. For example, the use of surface active agents reduces the surface tension of water droplets, thus allowing them to coalesce into large drops. However, additional problems arise in disposing these chemical demulsifiers in the aqueous phase and in the recovered-oil phase. The pH effect can be used to break oil-in-water emulsions, but it is not significant in the separation of water-in-oil dispersions.

Centrifugation, sometimes an efficient separation technique for some emulsions, has a high operating cost. Heat treatment can reduce the viscosity of the oil phase, thus allowing any water droplets to fall more rapidly through the oil, and also to assist in the separation of the entrained gas. However, heat treatment, as well as the use of chemicals, is expensive, with heating has a further disadvantage of high fuel consumption especially when large amount of dispersion is to be treated.

External electric fields have been applied quite extensively to break waterin-oil dispersions. The"electric-treaters"developed for this purpose use the electric field strength to promote coalescence of the aqueous drops in oil and thus enhance phase separation, although the exact manner in which this occurs is not yet clearly understood. Electrocoalescence requires that the continuous phase to be a reasonably good electrical insulator, satisfied by the oil, compared to the dispersed phase, satisfied by the aqueous phase. With regards to this, the dispersed phase should have a significantly higher dielectric constant than that of the continuous phase.

Conventional electrocoalescers are large vessels containing electrodes between which a'treating space'exists where dispersed water droplets grow mainly by electrocoalescence, and a'settling zone'where gravitational phase separation takes place under very low velocity flow, hence the need for large vessels. However, this leads to difficulties offshore where one of the main problems, particularly in view of the current trend for floating or minimally sized

plant, is to decrease the weight and size of topside equipment in order to economise on platform structure.

Intensification of the coalescence process therefore would reduce the residence time of the aqueous droplets, which not only address the volumetric throughput, but would also enable the application of smaller, lighter and, as a consequence, cheaper units. Therefore, the inventions presented here have been specially designed in such a way as to incorporate these features, and the inventions, being portable, are also capable of being installed into existing pipeline systems without any major modification to the existing pipelines.

In order to simplify the description here, the three distinct methods (i. e. the electrostatic-enhanced separation, the gravitational separation and the hydrocyclonic separation) will be discussed separately. However, the whole point in the inventions are to show hereinafter that the combination of the electrostatic and hydrocyclonic methods can further effectively enhance the separation of water droplets dispersed in oil.

Electrostatic fields, as aforementioned, have been used mainly in the petroleum industry for the separation of water from water-in-oil dispersions.

This is usually being carried out by applying a high electric field onto the flowing dispersion to cause coagulation and coalescence of water droplets. Some coalescence can occur naturally due to Brownian motion and differential sedimentation but these effects are insignificant compared to electrostatic coalescence. An irreversible rupturing of the emulsion usually occurs in high electric fields due to the coalescence of droplets, while a reversible mechanism is observed in low electric fields. When two droplets approach each other, the interface is separated by a thin film of oil which basically determines emulsion stability. Therefore, demulsification requires rupturing of the interfacial films between the droplets. Consequently, the main features of an applied electric field are to promote contact between the dispersed droplets, to assist in droplet-droplet coalescence, and to promote droplet-interface coalescence, thereby completing

phase separation. From experiments carried out, observations have been mde that by applying a pulsating voltage, droplet chains can be produced during periods of high voltage, followed by rapid coalescence during periods of no voltage. Recent experimental results also show that a proper pulse frequency can further enhance the coalescence of water droplets.

The characteristics or properties of the dispersion system itself determine the practicality of using high electric fields to separate the immiscible components in a dispersion. Dispersions containing high aqueous phase content will tend to short-circuit and cause the applied electric field to collapse, reducing the coalescence efficiency. Crude oils also contain various unknown impurities and surface-active components such as indigenous solids, wax crystallites, asphaltenes and resins. When these components are present at the oil-water interface, they may impart considerable stability to the emulsion, as well as rheological property changes to the system.

In settling or gravity separation, the drops are separated from the continuous liquid phase by gravitational forces acting on the drops. In free settling, the fall of a drop is not affected by the walls of the vessel and by other drops. Hindered settling occurs when drops are crowded and settle at a lower rate. When a drop is moving through a liquid, a number of forces will be acting on the drop. Firstly, a density difference is required between the drop and the continuous phase liquid. An external force of gravity is needed to impart motion to the drop. If the densities of the drop and the continuous phase liquid are the same, the buoyant force on the drop will counterbalance the external force and the drop will not move relative to the liquid. Because the density of water is higher than that of the oil, the water drop will move downwards in a stationary oil phase.

However, for many cases in settling, a large number of drops are present and the surrounding drops interfere with the motion of individual drops. The velocity gradient surrounding each drop is therefore affected by the close presence of other drops. The drops, while settling in the liquid, displace the liquid, and an appreciable upward velocity of the liquid is created. Hence, the velocity of the

liquid is appreciably greater with respect to the drop than with respect to the apparatus itself.

The third method, i. e. the swirling process, increases the mass forces on particles or droplets and thus extends gravitation to finer drop sizes and to emulsions that are normally stable in the gravity field. Besides, it can also eliminate the need for reducing the viscosity of the oil, and thus eliminate the need of using chemical and/or heat treatment for the oil. The equipment available for this purpose can be generally classified as fixed-wall devices (i. e. hydrocyclones) and rotating devices (sedimenting centrifuges). Most hydrocyclones in current use are designed for removing a more dense dispersion from the continuous phase. Hydrocyclones have no rotating parts, with the emulsion being tangentially ejected into the interior of a cylindrically-walled vessel to cause the emulsion to flow circumferentially within the vessel. This generates vortex within the hydrocyclone body, causing the water droplets to migrate radially towards the vessel cylindrical wall. Water droplets, being heavier than the oil, will migrate toward the outside perimeter of the fluid and to the inside of the containing wall, due to the hydrocyclonic force generated. Therefore, the advantages of a hydrocyclone system are the low mean residence time, compactness of the unit, which being basically cylindrical can easily withstand high pressure, the gain in reliability due to the avoidance of moving parts and elimination of fine clearance elements that can be choked or need replacing.

The complexity in the separation of two immiscible liquids in a hydrocyclone is accentuated when compared with that of solid particles removal from a liquid, due to the effect of shear forces on the dispersed liquid droplets. These forces are maximum where the velocity gradients in the hydrocyclone are highest and tend to be at places where the separating effect is the greatest. This may cause breakage of possible agglomerates or floes which is not desirable in separation but very suitable for classification. Liquid droplets will tend to start breaking up when a critical shear force is reached and efficiency will then fall off

at higher flow rates. Therefore, the present invention here is designed to produce regions of fast swirling to promote separation but at the same time it can avoid break-up of the drops in regions of high shear.

Since the present inventions, as aforementioned, also work closely on a density difference between the water droplets and the oil phase, water droplet size is critical to the separation efficiency. The separation efficiency in itself is only an efficiency measurement of the present inventions for a particular water and oil flowrate with a given water droplet size. Consequently, the requirements for control and measurement of the parameters under investigation can be looked at in terms of the amount of water and oil in the influent and effluent flows. The overall flow rate through the present inventions affects the separation efficiency greatly since it determines the strength of the vortex and hence the trajectory of each water droplet. The higher the viscosity of the continuous liquid phase, the greater the frictional resistance to the migration of the dispersed water droplets through it and also the more likely the occurrence of droplet break-up as shear effects will increase.

Therefore, it is clear that by combining the electrostatic force and the hydrocyclonic force, a major improvement to the coalescence of water droplets and separation efficiency can be achieved. This will move the separation technology towards the direction of small, portable and yet efficient separator.

The present invention has been designed in such a way as to achieve the aforementioned benefits, and also it is cost-saving and easily maintainable.

BRIEF DESCRIPTION OF THE DRAWINGS The inventions will now be further described and illustrated by reference to the accompanying drawings, in which :- Figure 1 is a perspective view, in schematic form, of the first current invention employing high pulsed d. c. electric fields combined with gravitational forces for use in the separation of aqueous-in-oil dispersions. This combination is termed as'the first combination'as hereinafter be described.

Figure 2 is a front view of the metallic cone (8), together with its attachments.

The cone (8) serves as the high voltage electrode with positive polarity.

Figure 3 is a plan view of the cone (8), together with its attachments. The four holes (17) are for the flow of the oil from the cone (8) to the outlet tube (4).

Figure 4 is a perspective view of the metallic strip (15) with its attachments to the inside of the device head (21).

Figure 5 is a perspective view of the metallic cone support (19).

Figure 6 is a perspective view, in schematic form, of the second current invention, designed and modified for use in the separation of aqueous-in-oil dispersions or emulsions using high electric fields of pulsing nature combined with hydrocyclonic forces. This combination is termed as'the second combination'as hereinafter be described.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS The technical aspects and features, the separation techniques and all embodiments of the present inventions should hereinafter be described in detail with reference to the accompanying drawings. Nevertheless, it should be kept in mind that the present inventions are not limited to the illustrated embodiments. The first combination of electrostatic and gravitational forces, also termed as'the first combination'and/or'the first invention', for the separation of aqueous-in-oil dispersions will hereinafter be described in detail with reference to Figures 1 to 5.

Thereafter, the second combination of electrostatic and hydrocyclonic forces, also termed as'the second combination'and/or'the second invention', will be described in detail with reference to Figures 2 to 6, and comparisons between these two combinations will be made accordingly.

Altogether there are six major figures given together with these inventions.

All the six figures should be used together in order to have a clear picture and description of the invention as a whole.

Referring to Figure 1 in the first place, the dispersion consisting of water droplets dispersed in oil enters the first invention (or electro-mechanical coalescer-separator) through inlet tube (3). It is very important that the whole body of the separator is grounded with direct earth connection to the separator head (21), the middle shaft (7), the upper needle valve (6) and the needle valve (5) through an earth cable (2) screwed to the body of the device head (21). Only the cone (8), preferably made of good conductive and non-corrosive material, is connected to the high voltage supply by a high voltage cable (1). It is preferable to employ pulsed d. c. electric field with a certain frequency pulsed between 0.1 Hz and 10.0 Hz, as experimentally discovered. The cable (1) is carefully attached to the body of the cone (8) with a screw (10). The entrance of the high voltage cable (1) to the separator head (21) is sealed by a screw seal (22), thus preventing any liquid from leaking through the entrance. The water droplets will get

charged in several places in the separator: between the metallic cone (8) and the metallic strip (15) around the upper part of the Perspex container (23), between the cone (8) and the accumulated water layer at the bottom of the Perspex container (23), and between the cone (8) and the metallic cone support (19). All these are enclosed in a transparent Perspex container (23), enabling the coalescence and the separation processes to be visible. The electric fields between the cone (8) and the metallic strip (15), and between the cone (8) and the cone support (19) have been set up in such a way as to be perpendicular with respect to the general direction of the dispersion flow. However the arrangement of the cone (8) with the accumulated aqueous body at the bottom of the container (23) is such that the electrostatic field set up is in the same general direction of the dispersion flow. These different arrangements have been observed to have different effects on the capture of the individual water drops. The dispersion flow will make a turn in order to enter the cone (8) from the bottom. In this instance, the charged water droplets are attracted towards the accumulated water layer at the bottom of the Perspex container (23), due to electrostatic attractive force and also gravitational force. Therefore the height of the water layer plays a very important role here. From experimental results, there is clearly an optimum height to achieve an optimum separation efficiency of water droplets from the oil continuous phase.

The treated organic or oil phase leaves the invention through the outlet tube (4) while the coalesced water layer accumulates at the bottom of the Perspex container (23). The needle valve (5) with hole (13) is used to drain out the body of water accumulated at the bottom of the separator. This is important in order to maintain an optimum level of water body below the metallic cone (8). The needle valve (5) can be automatically controlled to release any over-accumulated water in order to make human intervention to a minimum.

One of the major advantages of this invention is that it can coalesce and retain water droplets at the same time, thus producing cleaner oil at the outlet (4). The size of this invention is significantly very small compared to conventional

electrostatic separators, enabling it to be installed into any existing treatment facility without any major modification to the pipelines. This is also due to the fact that the inlet tube (3) and the outlet tube (4) can be changed easily as these are actually screwed-on connectors.

The applied potential is preferably a pulsed d. c. electric field with voltages ranging from 0.5 kV to 4 kV, depending on the water content of the oil and also on the average water droplet size. The average water droplet size can range from a few micrometers to a few millimeters in diameter.

Details of the high voltage electrode, i. e. the metallic cone (8) are shown in Figure 2 and Figure 3. The cone (8) is attached permanently to the cone head (9), with the cone head (9) as an insulator between the metallic cone (8) and the the separator head (21). Therefore, the cone head (9) should be made of any good electrical insulator. The hollow cylinder (16) at the top middle of the cone head (9) is to position the whole cone (8) around the middle shaft (7). The hollow cylinder (16) and the middle shaft (7) are preferably made of any good conductive and non-corrosive material. From Figure 3, it can be see that there are four holes (17) around the hollow cylinder (16). These holes (17) are for the flow of oil from the inside of the cone (8). The high voltage cable (1) is carefully and cleverly attached to the internal of the body of the metallic cone (8) using a screw connection (10). As shown in Figure 3, the high voltage cable (1) is positioned through one of the holes (17).

Figure 4 shows one of the grounded electrodes, i. e. the metallic strip (15) around the internal upper section of the circular Perspex container (23). This round metallic strip (15) is connected to the separator head (21) by the metallic strip attachments (18), so that the metallic strip (15) is also grounded. The electrostatic field set up between the metallic cone (8) and the round metallic strip (15) is the major field in'order to charge the aqueous droplets in the dispersion entering the separator. Therefore, the separation distance between the metallic strip (15) and the cone (8) is crucial here as it greatly determines the electric field

strength generated between them. Drop deformation and, as a result, electrical short circuiting have been observed experimentally when the applied voltage is above a certain predetermined value.

Another major advantage of the present invention is that the whole arrangement of the metallic cone (8) together with the insulating cone head (9) and the hollow cylinder (16), can be detached easily from the separator head (21).

This is because the cone support (19), as shown in Figure 5, has been designed in such a way as to be removable from the middle shaft (7) and the insulating cone head (9). This feature enables the metallic cone (8) to be removed for various purposes such as cleaning and further modifications. The cone support (19) is actually a long hollow cylinder with a bigger diameter end to support the cone head (9). The long vertical hole (20) through the cone support (19) is to accommodate the middle shaft (7). The cone support (19) can be made of any conductive material but preferably of the same material as the one for the metallic cone (8). In each case, the skilled man will have no difficulty, given the present disclosure and embodiments, in designing an appropriate electrode arrangement to provide the correct electrostatic field.

Figure 6 shows the basic components of the second invention, designed and modified to separate water-in-oil dispersions by utilising pulsed electric fields together with hydrocyclonic forces. Generally, this modified present invention, termed as'the second combination', is also designed to treat any aqueous solution dispersed in any organic solution, but with higher flow rates. Referring to Figure 6, the dispersion of aqueous droplets in oil enters the present invention through the inlet tube (3). This inlet tube (3) has the same internal diameter as the one for the first combination. Therefore, with the same cross-sectional area for the flow, a higher flow rate will generate a higher inlet dispersion velocity. The inlet tube (3) for the flow of the dispersion into the invention is attached to the separator head (21) through a threaded connector (25). In this way, the invention, referring to the second combination, can also be installed into existing pipelines without any major difficulty. This is one of the advantages of the current invention

besides it being portable and cost saving. The material used for the inlet tube (3) and the threaded connector (25) is preferably a hardened plastic which is commercially available. The dispersion will then go through the separator head (21) which is made of metallic material in order to set up an earth connection easily. The separator head (21) and the dispersion inlet tube (1) of the second combination are designed in such a way as to generate a swirling flow from the incoming dispersion in order to produce a tangential or circumferential motion within the body (23) of the present modified invention. This is to produce vortex within the body (23) to cause the aqueous drops to migrate radially towards the vessel cylindrical wall (23) of the present invention of the second combination.

The cylindrical wall (23) here is of a uniform cross-sectional area while that of the first combination has an increasing cross-sectional area from the bottom to the top.

The high voltage cable (1) is connected to the metallic cone (8) by a screw connector (10), as in the first combination aforementioned, in order to make the cone (8) a high voltage electrode. The cone (8) is preferably made of a good conductive and corrosion-resistance material. The other end of the high voltage cable (1) is connected to EHT supply with a positive polarity. The high voltage cable (1) is cleverly inserted into the inside of the invention by a screw seal (22). The EHT supply used here is preferably able to produce between 0 and 30 kV of pulsed electric potential. Nevertheless, the electric potential usually used is between 1 and 6 kV, pulsed at between 0. 1 and 10 Hz. Moreover, an optimum electric field exists together with an optimum applied frequency, as in the first combination. Except for the metallic cone (8), the whole of the invention is completely earthed. The ground cable (2) is connected through the separator head (21) by a screw seal (29), together with a threaded connector (30).

As in the first invention, the electrostatic field in the second invention is also established in several areas in the second invention : between the metallic cone (8) and the metallic strip (15) around the upper part of the Perspex body (23), between the metallic cone (8) and the middle shaft (7), and between the

metallic cone (8) and the bottom plate (27). The bottom plate (27) thus should be preferably made of metallic material. In the second combination, the bottom

plate (27) can be detached from the cylindrical body (23) by the bottom bolt (31).

However there is no such detachable bottom plate in the first combination.

The aqueous or water drops, will migrate to the metallic strip (15) due partly to the vortex generated by the swirling flow and partly to the electrostatic attraction forces between the charged drops and the strip (15). This will also cause the drops to coalesce with themselves, forming bigger drops which are more susceptible to gravitation. After some time, an aqueous layer can be observed to form on top of the bottom plate (27). This aqueous layer is crucial to the enhancement of the separation efficiency, as its height from the bottom of the metallic cone (8) determines the attraction and thus coalescence rate of dispersed water drops into the surface of the aqueous layer. The level of this aqueous layer can be controlled by a screw valve (26) connected through the bottom plate (27).

The bottom plate (27) is firmly attached to the Perspex body (23) by a bolt (31) into the middle shaft (7).

In order to further enhance the separation of water droplets from oil continuous phase, the direction of the flow of water/oil dispersion is made to turn to the inside of the cone (8), as similar in the aforementioned first invention, before being released from the invention through the outlet tube (4). The outlet tube (4) is firmly attached onto the separator head (21) by a connector (28). This design is beneficial when the invention is needed to be installed into existing pipelines; no major modification is necessary as the size of the outlet (4) can be changed easily to fit into the existing pipeline.

The metallic cone (8) in the second invention is significantly longer than the cone (8) as shown in Figure 2 for the first invention. This is due to the fact that the modified invention (i. e. the second invention) is significantly larger and longer than the first invention or the first separator. The cone (8), made from metallic material, is actually a hollow cylinder of decreasing diameter from the

bottom to the top. It is insulated from the separator head (21) by a cone head (9) of insulating material preferably a hardened plastic. Figure 2 also shows how the high voltage cable (1) is connected to the cone (8) by a screw connector (10).

This is connected in such a way as to minimise any effect or disturbance to the flow of the water-in-oil dispersion. Figure 3, a plan view of the whole arrangement, shows that there are four identical holes (17) on the top surface of the cone head (9). These holes (17) function as outlets for the oil flowing from the inside of the cone (8) to the separator head (21). It can also be seen from Figure 3 that the high voltage cable (1) is attached to the cone (8) through one of these holes (17). However, in the second invention or separator, there is no hollow cylinder (16) as shown in Figure 2 and Figure 3 for the first invention.

The metallic strip (15) around the upper part of the Perspex body (23) for the second invention or combination is similar to the one shown in Figure 4 for the first invention except that the metallic strip (15) in the second invention is much larger and wider than that in the first combination. There are four attachments (18) to make a contact with the separator head (21), forming a wellgrounded system. The electrostatic field created between the cone (8) and this metallic strip (15) is of the highest intensity compared to the other two areas mentioned above.

From experimental observations and results obtained, the second invention or combination is more efficient than the first invention for higher flow rates of water-in-oil dispersions. This is due to the fact that there is the extra swirling action in the second invention, generating hydrocyclonic forces to capture the water droplets in the second combination.

Claims

CLAIMS : 1. An invention for the separation of the components of a liquid/liquid dispersion or emulsion, combining the steps of applying an electrostatic field and a gravitational force simultaneously to the dispersion, with this combination termed as'the first invention'and/or'the first combination'.
2. An invention for the separation of the components of a liquid/liquid dispersion or emulsion, combining the steps of applying an electrostatic force and a hydrocyclonic force simultaneously to the dispersion, with this combination termed as'the second invention'and/or'the second combination'.
3. The inventions, according to Claims 1 and 2, are adapted and suitable for use in a continuous liquid/liquid separation process, both for the first invention and the second invention.
4. The inventions, according to Claims 1 and 2, wherein the dispersion treated can be of any type of aqueous liquid phase, dispersed in the form of droplets, in an organic liquid phase.
5. The liquid phases, according to Claim 4, should be an aqueous or water liquid phase of a high dielectric constant and an organic or oil phase of a much lower dielectric constant.
6. The methods and apparatuses, according to any one of the preceding claims, wherein the applied electrostatic field should be a pulsed unidirectional electric field between a relatively high voltage electrode and a relatively low voltage electrode.

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7. The apparatuses, according to any of the preceding claims, wherein there are more than one earthed or grounded electrodes and only one high voltage electrode in the first invention, as well as in the second invention.
8. The inventions, according to any of the preceding claims, wherein high electric fields are applied by means of a conical electrode as the high voltage electrode for the first invention and the second invention.
9. The invention, according to Claim 1 and Claims 3 to 8, wherein the voltage applied to the relatively high electrode is between 0. 5 kV and 4. 0 kV in the first invention or combination.
10. The invention, according to Claim 9, wherein the voltage applied across the electrodes is pulsed at a predetermined frequency between 0. 1 Hz and 10 Hz in the first invention or combination.
11. The invention, according to any of the preceding claims, wherein the

potential applied to the high voltage electrode is between 0. 5 kV and 6. 0 c kV and the frequency is pulsed at between 0. 1 Hz and 10 Hz or more in the second invention or combination.
12. The inventions, according to Claims 1-11, wherein the gravitational force is enhanced by the attraction of charged water droplets toward the grounded body of water phase at the bottom of the apparatus in the first invention and in the second invention.
13. The invention, according to Claim 2, wherein the hydrocyclonic force is generated by the swirling motion of the flow of dispersion between the central electrode and the cylindrical wall in the second invention or combination.

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14. The inventions, according to any of the preceding claims, wherein the separation of the water droplets from the continuous oil phase is further enhanced by the coalescence of charged water droplets into the grounded layer of water phase accumulated at the bottom of the apparatuses for both the first invention and the second invention.
15. The invention, according to Claim2, Claims 3-8 and Claims 11 - 13, can generate different magnitudes of the hydrocyclonic force by increasing or decreasing the inlet flow rate of the dispersion for the first invention.
16. The inventions, according to any of the preceding claims, wherein the cone (8), the metallic strip (15), the metallic cone support (19) and the middle shaft (7) are preferably made of any good conductive and corrosion-resistance material for both the first invention and the second invention.
17. The inventions, according to any of the preceding claims, wherein the inventions, with reference to both the first invention and the second invention, should be completely electrically-grounded for obvious safety reasons.
18. The apparatuses, according to any of the preceding claims, wherein they are very suitable for direct installation into any existing facility due to the flexible inlet and outlet connections, both for the first invention or combination and for the second invention and combination.
19. The inventions, according to any of the preceding claims, wherein the separators are light and portable as well as are suitable for application in diesel engines, both for the first invention and the second invention.

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20. The inventions, according to the above claims, that the second invention or combination is more efficient than the first invention or combination for treating larger flow rates of aqueous-in-oil dispersions.
21. The inventions, according to the above claims, are suitable for application in any edible oil industry as both the first invention and the second invention are safe from contaminating the edible oil.
22. The inventions, referring to both the first invention or combination and the second invention or combination for use in the separation of two different immiscible phases of a liquid/liquid dispersion or emulsion, are substantially as herein described and shown with reference to the accompanying drawings.