WO2004015031A1

WO2004015031A1 - Method and apparatus for monitoring the power of a coalescer

Info

Publication number: WO2004015031A1
Application number: PCT/GB2003/003219
Authority: WO
Inventors: Spencer Edwin Taylor
Original assignee: Bp Oil International Limited
Priority date: 2002-08-07
Filing date: 2003-07-25
Publication date: 2004-02-19
Also published as: GB0218325D0; AU2003251347A1

Abstract

A method and apparatus for monitoring the coalescence power of a coalescer comprising a coalescing material, wherein first and second electrodes are in electrical contact with the coalescing material, a source of electromotive force (EMF) and a means for indicating the dielectric properties between the electrodes, in which the dielectric properties related to the coalescence power of the coalescer. The method and apparatus can be used to determine when the coalescer needs to be replaced, especially for use in removing water dispersed in hydrocarbon such as fuel, particularly aviation fuel.

Description

METHOD AND APPARATUS FOR MONITORING THE POWER OF A

COALESCER The present invention concerns coalescers. In particular, the present invention concerns coalescers that are used to coalesce from a continuous phase, dispersed liquids such as water droplets which are present as a fine dispersion, especially as a dispersion in a hydrocarbon e.g. diesel, gasoline or jet fuel. The present invention also provides a method and apparatus for the monitoring of water content of a continuous phase, and in particular in liquid hydrocarbons e.g. diesel, gasoline or jet fuel.

US 4609458 relates to a device for removing moisture from oil that is capable of adsorbing and removing moisture dissolved in oil before it dissociates from the oil. The device uses a moisture-adsorbing porous ceramic material, the fine pores of which being smaller than the molecules of the oil so that the oil molecules do not enter the pores, but being about the same diameter as water molecules and thus capable of trapping water molecules such that the porous ceramic material adsorbs moisture dissolved in the oil. A coalescer may be used to coalesce a dispersed liquid from a continuous phase. Coalescers may be liquid-liquid coalescers, wherein finely dispersed liquid droplets, such as water, are separated from a liquid phase such as liquid hydrocarbons, for example jet fuel. Alternatively, coalescers may be gas-liquid coalescers wherein finely dispersed liquid droplets are separated from a vapour or gaseous phase.

Unlike adsorbers/absorbers, coalescers typically can coalesce many times more dispersed liquid than they can adsorb and/or absorb.

A coalescer comprises a coalescing material across or through which the continuous phase with the dispersion is passed. The coalescing material may typically be porous or fibrous coalescing material. The coalescing material may typically be in the form of mats, beds or layers of a porous or fibrous coalescent material.

Typically, a coalescer for separation of a dispersion of water in a hydrocarbon, may comprise a cylindrical central core around which are one or more layers of the coalescing material to form a coalescing bed. The liquid water/hydrocarbon is introduced into the central core and passes radially through the coalescing bed such that the surface-active properties of the coalescing material cause the water droplets to coalesce and consequently form larger drops. These drops can then either pass radially through the one or more layers of the coalescing bed and then drop from the outer layers as discrete drops, or pass through the core as large drops of water in the liquid in a coarse dispersion from which the water may then be subsequently separated.

A coalescer can become so saturated with dispersed droplets such as water, that it can no longer continue to coalesce dispersed droplets. Furthermore, when the coalescer is being used to remove dispersed water droplets from a fuel containing fuel additives, the fuel additives may attach themselves to the surface of the coalescing material of the coalescer causing a decrease in its coalescence power. Coalescence power is the ability of the coalescer to coalesce a dispersed liquid from a continuous phase. As a result of this saturation and/or the additive attachment, the coalescer has to be replaced.

Presently, coalescers such as for fuel are subjected to routine change-out after 3-5 years in continuous use. In practice it is not possible to estimate exactly when a coalescer will fail and consequently this allows for the possibility of liquid containing dispersed droplets passing through a failed coalescer. This occurrence is normally evident by for example fuel quality checks.

Accordingly, the present invention provides a method for monitoring the coalescence power of a coalescer comprising a coalescing material, wherein at least one first electrode is in electrical contact with the coalescing material and at least one second electrode is in electrical contact with the coalescing material distant from the first electrode, the method comprising connecting said electrodes to a source of electromotive force (EMF) and to a means for indicating one or more dielectric properties between said first and second electrodes, and relating said dielectric properties to the coalescence power.

The present invention also provides apparatus for monitoring the coalescence power of a coalescer comprising coalescing material, said apparatus comprising a) at least one first electrode adapted for electrical contact with the coalescing material, b) at least one second electrode adapted for electrical contact with the coalescing material c) at least one source of EMF capable of electrical conducting attachment to the at least one first electrode and to the at least one second electrode, and d) at least one means adapted to indicate in use, one or more dielectric properties between said first and second electrodes.

The present invention provides a method and apparatus to monitor the coalescence power of a coalescer by measuring its dielectric properties.

Coalescence power is the ability of the coalescer to coalesce a dispersed liquid from a continuous phase.

The one or more dielectric properties may be one or more properties selected from the group consisting of conductance, resistance and capacitance.

The coalescing material may be a suitable fibrous or porous material. Suitable porous materials include powders, granular solids and porous monolithic materials. Suitable granular materials include sand and diatomaceous earth. Preferably, the coalescing material comprises a fibrous material, particularly in the form of mats, beds or layers.

Preferably, the coalescer and coalescing material are suitable for the separation of water from a liquid comprising dispersed water droplets, such as the separation of water from one or more liquid hydrocarbons, and in particular from aviation fuels. However, although the present invention will from herewith be illustrated with respect to a coalescer for use in the separation of water from hydrocarbons, the method and apparatus of the present invention can be applied to coalescers for use in other separations, such as the separation of a dispersion of a liquid in a gaseous phase, and particularly of a dispersion of water from a gaseous phase.

The coalescer may comprise a central core into which a liquid dispersion of water in hydrocarbon may be introduced. This central core may be surrounded by one or more layers of a fibrous coalescing material to form a fibre bed.

The fibre bed may be comprised of fibres of a solid of high surface to volume ratio. The fibres may be of uniform diameter. Similarly, the pore size and/or density may be uniform throughout the fibre bed. Preferably however, the fibre bed comprises fibres with a range of different diameters, pore sizes, such as tapered pore structures, and densities. The fibres of the fibre bed may have diameters of 0.5 to 20 microns, preferably 1 to 15 microns. The fibres of the fibre bed may have pore sizes of 0.5 to 10 microns. The fibres of the fibre bed may have densities of 0.1 to 0.8 g cm^"3. The fibre bed may be a random mixture of such fibres, but preferably the fibre bed is in the form of graded layers, such as two or more layers of decreasing fibre diameter, to allow the coalescence of dispersions with a wide range of liquid droplet sizes. The fibres preferably have polar surfaces, and usually have an affinity for water but are not completely hydrophilic. The fibres may comprise a polymeric material with polar groups e.g. CONH, -COO- or alternatively the fibres can be inorganic e.g. glass fibre or mineral wool, especially coated with substances such as silicones and resins, such as glass treated with polar molecules. Examples of such fibres are glass fibres treated with a silane carrying a polar group such as organoxy-aminoalkyl silane or bonded with phenolic resins e.g. phenol formaldehyde resins to give hydrophilized inorganic fibres.

The fibre bed, when in the form of layers around a central core, is usually 10- 200cm, preferably 50-100cm in diameter and 10-500cm preferably 50-200cm in length. The fibres are usually held together by melding the surfaces, or by binding using a light phenolic resin, and typically the fibres are also retained in nets or gauzes to help maintain the integrity of the coalescer.

Coalescers and their structure and apparatus describing them are described in R.L.Brown and T.H.Wines, Hydrocarbon Processing Dec.1993 pp95-100 the disclosure of which is herein incorporated by reference.

The electrodes can be of a suitable electrical conducting material such as a graphite, but are preferably of a metal e.g. copper, nickel, aluminium, zinc, iron or stainless steel. Each electrode may be a 1 -dimensional conductor for example a wire or may be a 2 dimensional conductor net, gauze or other two-dimensional network.

When the coalescing material is in the form of a fibre bed, each electrode usually extends longitudinally along the coalescer bed, for example extending partially or entirely along the length of the fibre bed. Preferably, the electrode is a metal gauze. Preferably the gauze is positioned in a fibre bed between two fibrous layers. The first and second electrodes may be same for example a wire or a gauze as herein described. The first electrode may be a metal gauze positioned within the fibre bed or on the outermost of the fibrous layers, in contact with its external surface.

The second electrode may be positioned in the coalescer core in contact with the innermost of the fibre layers, for example, to form a hollow metal core to the fibre layers, and may extend partially or entirely along the length of the coalescer core.

The electrodes constitute part of an electrical circuit and are usually connected to the source of EMF and to the means for indicating the dielectric properties via insulated electrically conducting wires preferably copper, nickel or aluminium wires.

The electrodes are usually permanently located in the coalescer. Thus the first electrode may be a metal gauze in permanent electrical contact with the coalescing material and located between the fibres or on the outermost layer and the second electrode may be in permanent electrical contact with the coalescing material and located in the coalescer core.

Alternatively, the electrodes may be placed into electrical contact with the coalescing material when a measurement of the coalescence power is required.

The electrodes when in electrical contact with the coalescing material may be periodically or constantly attached to the EMF source and the means for indicating the dielectric properties to allow periodic or constant monitoring of the coalescence power.

Preferably the coalescer is monitored constantly.

Depending on the measurements to be made, the EMF source may be an alternating current (AC) source or a direct current (DC) source and can be supplied from the main electricity network but is preferably supplied by a battery. The source may be solar powered.

The means for indicating the dielectric properties may be provided by a suitable meter. For example, indicating the dielectric properties may be achieved by measuring a current flow between the first and second electrodes, or by measuring properties such as one or more of the conductance, the resistance and the capacitance of a circuit formed between the source of EMF and the first and second electrodes.

Alternatively, the means for indicating the dielectric properties may be an indicator that switches on/off for example a bulb or a bell, when a current between the first and second electrodes reaches a predetermined threshold.

In some certain embodiments more than one measurement of the dielectric properties may be used.

Relating the dielectric properties to the coalescence power may be achieved, for example, by comparing the dielectric properties prior to exposure to a continuous phase comprising droplets (for example a liquid phase, comprising water) with the dielectric properties during exposure to the continuous phase comprising droplets.

Relating the dielectric properties to the coalescence power may be achieved by comparing the dielectric properties under conditions where the coalescer is coalescing droplets from a continuous phase efficiently, with the dielectric properties in the situation where the coalescer can no longer coalesce droplets from said continuous phase sufficiently.

A calibration curve may be produced by measuring the coalescence power after various exposure times to continuous phases having known dispersed droplet content, for example of known dispersed water content and this allows the method and apparatus of the invention to predict the lifetime of a coalescer in use with that continuous phase. The dielectric properties may be measured between a first and second electrode for example wherein the first electrode is a gauze between two layers of a fibre bed and the second electrode forms a hollow metal core to the fibre bed. Alternatively, the dielectric properties may be measured between a number of electrodes and in a preferred embodiment of the invention, more than one electrode for example 2-6, which may be in electrical contact with the coalescing material at various positions, for example at various positions extending radially from a core of the coalescer.

Pairs of electrodes (equivalent to a first electrode and a second electrode as previously described) may be connected to the EMF source and a means for indicating the dielectric properties as and when required to provide a separate measurement of the dielectric properties between the first and second electrodes. Alternatively, all of the electrodes may be connected in parallel to the EMF source and a means for indicating the amount of current flow. The dielectric properties between any two of the electrodes can then be monitored by isolating the other electrodes from the circuit. In a preferred embodiment one of the electrodes forms a hollow metal core to a fibre bed as described above, and the dielectric properties measured between this and each of the other electrodes as required - that is, the hollow metal core is the second electrode and the remaining electrodes form a number of alternative first electrodes. The coalescers as herein described may be used to coalesce water dispersed in a continuous phase and the coalescence power of the coalescer may be monitored either periodically but is preferably monitored constantly whilst in use. The continuous phase is preferably a hydrocarbon liquid such as a fuel e.g. diesel, gasoline or jet fuel. The amount of water dispersed in the continuous phase is usually 10-1000 ppm for examplel 00-500 ppm by weight. The dispersed water in the continuous phase is usually in the form of a fine dispersion of water droplets ranging from micron to sυbmicron sized droplets such as 0.1 to 0.5 microns. The coalescer usually has sufficient coalescence power to cause the dispersed water droplets to grow in size such as from a size of less than 1 micron to produce drops of a size of at least 1mm.

The continuous phase may be passed through the coalescer at a flow rate of usually 75-200 L/min, preferably 95-135 L/min for example 1 15 L/min.

The first and/or second electrodes may be adapted for electrical contact to a coalescing material on the inner and/or outer surface of a coalescing bed or may be capable of being positioned between the layers of a bed. The electrodes can be any suitable electrical conducting material as hereind escribed. The first electrode is preferably a metal wire, gauze or longitudinal strip. The first electrode is preferably a wire or longitudinal strip 50-200cm for example 100cm in length and may extend throughout the length of a fibre bed. The second electrode may be same as the first electrode but is preferably a metal coalescer open core extending entirely through the length of the coalescer core. The apparatus may comprise a number of first electrodes for example 2-6.

The EMF source is preferably a battery. The means for indicating the dielectric properties may be provided by a meter to measure the current flow, the capacitance, the conductance or the resistance of the circuit but is preferably a conductance or capacitance meter. Preferably, at least one first electrode, at least one second electrode, at least one source of EMF and at least one means for indicating the dielectric properties are capable of being connected in a circuit in series via electrical conducting means for example insulated wires preferably copper, nickel or aluminium wires. In a preferred embodiment of the invention the first electrode is a metal gauze located in between the fibres and in permanent electrical contact with the coalescing material and the second electrode is a metal coalescer core. Advantageously the apparatus comprises a coalescer with a number of first electrodes for example 2-6, integral with the fibre bed located at various positions extending radially from a metal core second electrode.

Usually many coalescers (in parallel) for example 2-8 are used to remove water from a hydrocarbon fuel and when a number of coalescers is used, at least one coalescer is provided with the apparatus according to the invention and preferably all of the coalescers are so provided.

Preferably, the means for indicating the dielectric properties comprises measurement of conductance and/or capacitance between the first and second electrodes. For example, in use, an increase in the cell conductance and/or cell capacitance is indicative of a reduced coalescence power.

The method and apparatus of the present invention also allow the monitoring of fluctuations in the water content of a continuous phase, such as a fuel. Temporary losses of coalescing power, for example due to a slug of high or low water fuel, will result in a corresponding response in the conductivity of the coalescing material. Such responses can be distinguished from a permanent deactivation of the coalescing material, such as by aging of the coalescing material, which may be measured by monitoring the conductivity with use (such as with time on stream). In addition, unexpected and sustained increases in the conductivity or capacitance of the coalescing material will also indicate a loss of coalescence power and possible deactivation of the coalescing material, indicating that the coalescer may need to be changed.

A further embodiment of the invention provides a process for removing dispersed water from a continuous phase wherein the continuous phase is passed through at least one first coalescer comprising a fibre bed and its coalescence power is monitored by the method of the present invention. In the process, at least one first coalescer may be replaced λvith at least one second coalescer when at least one of its dielectric properties reaches a predetermined value.

The method and apparatus of the present invention can allow the monitoring of fluctuations in the water content of a continuous phase being introduced into a coalescer. The one or more dielectric properties of a coalescing material is thus dependent on the dispersed water concentration in the continuous phase. It is possible to use this property in a quantitative way to measure the dispersed water content of a continuous phase, such as a hydrocarbon.

Thus, the present invention also provides a method of measuring the dispersed water content of a continuous phase by contacting the continuous phase with a coalescing material, wherein at least one first electrode is in electrical contact with the coalescing material and at least one second electrode is in electrical contact with the coalescing material distant from the first electrode, the method comprising connecting said electrodes to a source of electromotive force (EMF) and to a means for indicating the dielectric properties between the first and second electrodes, and relating the dielectric properties to the dispersed water content of the continuous phase.

The continuous phase may be a gaseous or vapour phase, but is preferably a liquid phase, and most preferably is a hydrocarbon. The hydrocarbon, coalescing material, electrodes, electrical conducting means, source of EMF and means for indicating the current flow or capacitance are preferably as described above. The method is preferably used for measurement of the dispersed water content of a hydrocarbon fuel, such as a jet fuel. The amount of water dispersed in the continuous phase is usually 10-lOOOppm, for example 100-500ppm and especially 100-200ppm. The water may be in the form of a fine dispersion of water droplets ranging from micron to submicron sized droplets such as 0.1 to 0.5 microns.

Relating the dielectric properties to the dispersed water content of the continuous phase may be achieved, for example, by comparing the dielectric properties-on exposure to a continuous phase comprising a known dispersed water content with the dielectric properties on exposure to a continuous phase comprising an unknown dispersed water content. Preferably, a calibration curve is produced, for example, by measuring the dielectric properties on exposure to a series of continuous phases with known water contents, and this allows the method of the invention to predict the dispersed water content of a continuous phase from the dielectric properties measured from a coalescer in use with the continuous phase.

The present invention also provides an apparatus for measuring the dispersed water content of a continuous phase by contacting the continuous phase with a coalescing material, said apparatus comprising a) at least one first electrode adapted for electrical contact with the coalescing material, b) at least one second electrode adapted for electrical contact with the coalescing material c) at least one source of EMF capable of electrical conducting attachment to the at least one first electrode and to the at least one second electrode, and d) at least one means for indicating the dielectric properties between said first and second electrodes.

In one embodiment, the apparatus for measuring the dispersed water content of a continuous phase may be essentially the same as the apparatus for monitoring the coalescence power of a coalescer as described above - that is, the coalescing material may be part of a coalescer, and the dielectric properties or coalescence power of the coalescer may be related to the dispersed water content of the continuous phase. Alternatively, the apparatus may be specifically designed for measuring the dispersed water content of the continuous phase. In this case it may be sufficient for only a portion of the continuous phase, such as a portion of the liquid phase, to contact the coalescing material. The invention is illustrated with respect to the following examples and with reference to the Figures in which Figure 1 represents schematically apparatus for measuring the coalescing power of a coalescer, Figure 2 represents schematically a coalescer of the present invention, Figure 3 represents in graph form a relationship between water content of heptane and conductance, and Figure 4 represents in graph form the effect on conductance of adding water/Jet A-l mixture to Jet A-l .

In the examples the dielectric property that is indicated is the conductance between the electrodes. However, other electrical measurements may also be applied to the methods and respective apparatus of the present invention.

Example 1

Referring to Figure 1 a cell (1) was constructed which allowed a sample of fibrous coalescing material (2) to be positioned between two stainless steel perforate electrodes (3,4). The conductivity between the electrodes (a separation of typically 1-10 mm) was indicated with time using a conductance meter (5). A dispersion of water in a continuous phase (6) was pumped using a peristaltic pump (7) from a conical flask (8) and passed through the fibrous coalescing material (2) before being returned to the conical flask (8). The dispersion was kept in a highly dispersed state within the conical flask using a high shear mixer (9). The typical experimental system is shown in Figure 1. A coalescer cell assembly was constructed as described above as shown schematically in Figure 1. Heptane was used as the continuous phase. Passage of dry heptane through the cell in the absence of any coalescing material resulted in a baseline conductance of ca. 0 nS determined using a Wayne-Kerr Precision Component Analyser (operating at 10 kHz), previously calibrated using standard resistances. Glass wool fibres (coalescing material, 2) were then positioned between the two electrodes (3,4) and an increase in the conductance was observed to ca. 40 nS on flowing dry heptane through the cell. 1 vol% of deionised water was then added to the conical flask and incorporated into the heptane using the high shear mixer. A 500-fold increase in conductance to 20 μS was indicated by the meter (5).

The water concentration was then reduced to a low level but no effect on the conductance was observed. This indicated that the glass fibres had been irreversibly saturated with water. Example 2

In this example the glass wool from Example 1 was replaced with a coalescer fibre taken from a commercial (Facet) coalescer cartridge element wherein the coalescer fibre was less hydrophilic than glass wool. Wet heptane was again passed through the cell and the initial conductance was 1 1 μS. The water content in the heptane continuous phase was then reduced and the conductance dropped to 4.5 μS. The water content was then increased (by increasing the mixer speed, thereby entraining more water) and a further increase in conductance was observed showing that this material, and the conductance, was more responsive to changes in dispersed water content in the heptane continuous phase. This experiment also shows that the coalescer in Example 2 had retained its coalescing power whereas that in Example 1 was lacking in coalescing power.

Example 3

In this example a coalescer cell of slightly different design was made, as shown in Figure 2. Wliatman GFA glass microfibre filters were used as the coalescing material (2). 5-ml samples of heptane containing different amounts of dispersed water were prepared ultrasonically and passed sequentially through the coalescing material, whilst the conductance between the electrodes (3,4) was determined using a Wayne-Kerr Precision Component Analyser (operating at 10 kHz), previously calibrated using standard resistances. The resultant conductance changes following each successive aliquot addition are shown in Figure 3, and show linear behaviour. Example 4

In this example there was used the same apparatus as for Example 3 and again Whatman GFA glass microfibre filters were used as the coalescing material. A sample of commercial Jet A-l fuel without added water was passed through the coalescing material. A second sample of the fuel containing 50 ppm of dispersed water was prepared, the water having been pre-dispersed ultrasonically. The amount of water being passed through the module was increased steadily by making successive additions of the "wet" fuel to the initial sample using a 5ml syringe. The results are shown in Figure 4, and the conductance response is again seen to be linear.

This linear conductance response demonstrates the method and apparatus of the invention for measuring the dispersed water content of a continuous phase. Figure 2 thus represents one example of a suitable cell comprising coalescing material that may be used in the method or apparatus of the present invention for measurement of the water content of a hydrocarbon fuel. A sample of the fuel whose water content is to be measured may be passed through the cell, and through the coalescing material. A source of EMF may be connected to the electrodes allowing the current flow and/or cell conductance to be measured. The water content of the fuel can then be calculated, for example from known calibration curves.

Claims

Claims :

1. A method for monitoring the coalescence power of a coalescer comprising a coalescing material, wherein at least one first electrode is in electrical contact with the coalescing material and at least one second electrode is in electrical contact with the coalescing material distant from the first electrode, the method comprising connecting said electrodes to a source of electromotive force (EMF) and to a means for indicating one or more dielectric properties between said first and second electrodes, and relating said dielectric properties to the coalescence power.

2. Apparatus for monitoring the coalescence power of a coalescer comprising coalescing material, said apparatus comprising a) at least one first electrode adapted for electrical contact with the coalescing material, b) at least one second electrode adapted for electrical contact with the coalescing material c) at least one source of EMF capable of electrical conducting attachment to the at least one first electrode and to the at least one second electrode, and d) at least one means adapted to indicate in use, one or more dielectric properties between said first and second electrodes.

3. A method or apparatus as claimed in any one of the preceding claims in which the coalescer comprises a cylindrical central core around which one or more layers of the coalescing material form a coalescing bed.

4. A method or apparatus as claimed in claim 3 in which the central core is surrounded by one or more layers of a fibrous coalescing material to form a fibre bed.

5. A method or apparatus as claimed in claim 4 in which the fibre bed comprises fibres of a uniform diameter.

6. A method or apparatus as claimed in claim 4 or claim 5 in which the fibres have diameters of 0.5 to 20 microns, preferably 1 to 15 microns.

7. A method or apparatus as claimed in any one of claims 4 to 6 in which the fibre bed has pore sizes of 0.5 to 10 microns.

8. ^■ A method or apparatus as claimed in any one of claims 4 to 7 in which the fibres have densities of 0.1 to 0.8 gem^"3.

9. A method or apparatus as claimed in any one of claims 4 to 8 in which the first electrode is a metal gauze positioned within the fibre bed or on the outermost of the fibrous layers in contact with its external surface.

10. A method or apparatus as claimed in any one of claims 4 to 9 in which the second electrode is positioned in the coalescer core in contact with the innermost of the fibre layers.

1 1. A method or apparatus as claimed in any one of the preceding claims in which the one or more dielectric properties are one or more properties selected from the group consisting of conductance, resistance and capacitance.

12. A process for removing dispersed water from a continuous phase wherein the continuous phase is passed through at least one first coalescer comprising a fibre bed and its coalescence power is monitored by a method as claimed in any one of the preceding claims.

13. A process as claimed in claim 12 in which the continuous phase is passed through the coalescer at a flow rate of 75 to 200 L/min, preferably 95 to 135 L/min, for example 1 15 L/min.

14. A process as claimed in any one of claims 12 to 13 in which the continuous phase is a hydrocarbon liquid such as a fuel for example diesel, gasoline or jet fuel.

15. A process as claimed in any one of claims 12 to 14 in which the amount of water dispersed in the continuous phase is 10-1000 ppm for ex ample 100-500 ppm by weight.

16. A process as claimed in any one of claims 12 to 15 in which the dispersed water in the continuous phase is in the form of a fine dispersion of water droplets ranging from micron to submicron sized droplets such as 0.1 to 0.5 microns.

17. A process as claimed in claim 16 in which the coalescer has sufficient coalescence power to cause the dispersed water droplets to grow in size from a size of less than 1 micron to produce drops of a size of at least 1mm.

18. A method of measuring the dispersed water content of a continuous phase by contacting the continuous phase with a coalescing material, wherein at least one first electrode is in electrical contact with the coalescing material and at least one second electrode is in electrical contact with the coalescing material distant from the first electrode, the method comprising connecting said electrodes to a source of electromotive force (EMF) and to a means for indicating the dielectric properties between the first and second electrodes and relating the dielectric properties to the dispersed water content of the continuous phase.

19. Apparatus for measuring the dispersed water content of a continuous phase by contacting the continuous phase with a coalescing material, said apparatus comprising a) at least one first electrode adapted for electrical contact with the coalescing material, b) at least one second electrode adapted for electrical contact with the coalescing material c) at least one source of EMF capable of electrical conducting attachment to the at least one first electrode and to the ^'at least one second electrode, and d) at least one means for indicating the dielectric properties between said first and second electrodes.