IL33083A - A method of raising the separation rate of emulsions by means of an electric field - Google Patents

Description

A OF RAISING THB SEPARATION EMULSIONS BY MEANS OF AN ELECTRIC comprising a and a the produced the is in the In a comprising a plurality of consecutive extraction the throughput is determined by the separation rate of the in the A slow rate of separation calls for the provision of capacity separators and hence large of solvent for filling the present invention is concerned with achieving an increase in the rate of separation of the emulsion in the separators of a extraction plant by utilising effect of an electrical ί has already been proposed to separate emulsions of two liquid phases in an field in crude oil processes and in the refining of oils with aqueous acids or The phase that is to be separated in these processes contains wate an aqueous solution as the disperse which should not constitute than 10 to of the organic oily continuous Otherwise at the high potentials exceeding volts that short circuits may occur between the electrodes throug the conducting aqueous even when flow is and the short circuit currents far exceed 20 amps per square metre of electrode The current between the electrodes in the generally about 2 to 20 electrode which both the Mixture of the two phases and their reparation may be effected help of electrical Polar solvents in this context understood to liquids having a dielectric constant that at least twice that of the liquid that is to be of tho throughout rate in the extraction of of compounds with organic solvents in ara equipment has been in which method the separatio of the phases in the separators is an electrical field of 1 to 60 preferably 10 to 30 produced by applying a or voltage between 10 and preferably 110 to 220 to electrodes in the In the several electrodes are disposed at different levels and some of may be electrode may be sufficient if the separator casing is connected to earth as Potential is periodically applied and cut off in alternation ibr short intervals of time of roughly the duration of between and 2 In the phase that to be the polar phase should constitute between 20 and by by before the the mixture should so thoroughly that the polar phase is present as the disperse phase in the proportion of the phases is suitable for this purpose be adjusted by recycling part of tho phase from the separator into the preceding po ar p ase a re a ve y g e r ca or in which tho phace contains a g proportion a highly polar phase occur GO that the weak polar phase becomes disperse phase in the highly polar liquid as the continuous In phase in which the higher polar component the continuous the current the electrode carrying potential and earth is very high and causes further of the in other words it has an effect contrary to that of phase Even if a very weak electrical field of only 1 applied phase inversion cannot be prevented the previously proposed it is proposed to prevent phase inversion by alternately applying and cutting off the electrode potential at short regular intervals of it transpires that this does not prevent phase inversion but merely delays It now been found that it is not exclusively the Intensity of tho electrical field that he separation of phase but that the primary factor is the apparent power transferred to the phase measured as the product of voltage in Accordingly the present invention provides a of accelerating the separation into of a phase consisting of mutually or only sparingl or inorganic liquids in a extraction process plant 500 volts or to at least one horizontal electrode in the and wherein the power supplied to the or all electrodes is from to 500 of separatory As just the electrical power transferred to the phase mixture per square metre of surface should be from to 500 but s preferably 1 to 100 The best value for a particular phase mixture can be readily determined by preliminary The voltage depends upon the conductivity of the phase mixture that is to be separated and upon the distance between the electrode carrying potential and the earthed If the conductivity of the phase mixture is high the voltage should be than when it is It has further been found that disturbances in separation even before phase inversion takes the power applied is too The performance of the separator will then fall and the throughput volume must be reduced if a clean separation of the is to be achieved and of the foreign phase in the discharge of the pure phases is to be On the other the power is reduced the throu hput rate can be If these relationships are borne in pulsing of current by intermittently cutting the potential on and off is no longer optimum energy quantity depends little upon the of the electrode provided the of the of the is not to provido electrodes that too because this cause the distribution the of the separator to become Large favour the occurrence of phase inversion the power above the optimum whereas electrodes of average will still even when slightl eleotrode surface area which ia to of the araa of the separator is The electrodes are conveniently fixed horizontally and hence parallel to phase boundary surfaces that develop and the have the of perforated frames carrying wire or the Several electrodes bo at differen levels and electrodes may be a electrode will be suf icient when operating with the separator earthed a although an earthed electrode raay additionally provided The level of the electrodes should be so chosen as possible during electrode carrying will not be iinciersed in the continuous higher polar Preferably the electrode be ixed at a level which ia at to preferably to of the height of the discharge opening for the upper lighter above the of the If several electrodes are say it is preferable to earth centre electrode and to apply different potentials o the two higher should be applied to the is in the stronger polar phase should carry lower If the level of tho separating which is usually the stronger polar to the the this should be earthed and the potential applied to the centre the centre electrode be earthed or in which case only the uppermost electrode carries The electrcstatio separation be e with or will normally be preferred in order to avoid electrolytic corrosion which ma when a direct current is For adjusting to the favourable power the voltage may be varied by reference to the resultant current which may be between a and several The current can be measured whilst the voltage is varied by tapping it from a or by adjusting an electronic voltage the levels the layers of the separating phases the conductivity of the phase mixture may change in the course of operation of the for instance when the proportion of the stronger polar phase to the weaker polar phase shifts as a result of variations in it may be desirable to regulate the voltage automatically by conventional a controller adjusted to o power level varying the voltage by reference to the flowing a given the best also bo adjusted by the interposition of a particularly when using of the with an electrical Ceramic or plastics say are of insulating materials useful for this The thicker the the lower will be the power transferred At voltage regulation by the provision of a tapped may also be Whereas it was hitherto difficult electrostatically to separate liquid phase mixtures containing one polar ouch as water or an aqueous solution of an because very high currents causing phase inversion flow through the such can now be separated by applying so low a voltage to the electrodes that the optimum power level is not In order tha the invention may be more readily reference will now be made to the accompanying illustrates and by way of example a separator in vertical section in accordance with the lieferring now to the there separator which may be or preferably cylindrical separator has a 1 which is in the form of a About up the of the inlet separator is an 2 for a phase fixture 17 opening that is to be a for the pure lighter phase being at the top and a discharge 4 for the pure heavier phase at the the discharge there is a baffle 5 which is into the a chord of the circular Q the through which the pure phases can to their discharge o electrodes 9 and 10 horizontally fixed in separator and connected to supply 15 and 12 13 in the separator casing For an potential be applied to the two 8 and whereas the electrode 9 is In a practical embodiment the cylindrical separator be 600 its 2000 and the effective surface The top of the baffle 5 is above the bottom of the separator and the 6 at top as well as gap 7 at the bottoia are each 30 The upper electrode is 570 the centre electrode 9 is and the bottom electrode 10 is above the separator the phase 17 introduced into the separator hatching in the the heavier phase 18 hatching in separates at the whereas the lighter phase rises to the heavier phase flows through the gap 7 below the baffle 5 to the discharge opening the lighter phase flows out through the gap 6 at the top to the discharge opening the purpose of electrical fields betweon the the phase is pumped through separator at a rate at the outflowing pure phases contain up to of other this representing the performance of the The separator load expressed as of separa ory sur ace per and e power is expressed as By variation of the potential applied to the electrodes in functional dependence upon the the power con be readily determined in any particular invention will now be further illustrated by the following A phase mixture containing in by of water as heavier phase and a raixture of equal of toluene and benaene as the lighter phas is introduced nto the separator shown in The proportion by of the two phases is 1 A potential of 320 volts corresponding to a field intensity of 20 is applied to the upper electrode and a potential o 100 corresponding to a field intensity of is applied to the the electrode in the centre being Up to 97 of tho phase of the heavier can be The separator load is therefore in of the heavier In the absence of an field 2 tho load is 7 of the heavier The currents wore when the potentials were as At the upper electrode representing a power of throughout the At the the figures are corresponding to a lower of 140 VA the 52 1 proportion of the heavier phase phase was increased to The following electrical data at the 320 volte 11 100 volts 600 Phase inversion soon filled tho entire potential at tho electrode was to 20 volts The separator then functioned satisfactorily under a load of 22 current at upper electrode to and at tho bottom electrode 2 amps and corresponding the power to 24 composition of the phase mixture was the as in only tho top electrode was left in the separator for cooperation with the separator casing which was earthed as the At a potential of 320 a current of was power consumption was 3 2 load on the separator was 22 in torso of the heavier the heavier phase represented of tho the current rose to 10 load had to be reduced 3 2 to 20 in of the heavier potential was lowered to 250 the current dropped to so that the power consumption the separator load could 3 2 be raised again to 22 the heavier phase for of the The following resul Volte Amps 320 255 By the potential and the tho separator load could therefore be 3 2 by An capacitor was now connected between the potential and the The voltage at the capacitor input of 320 volte dropped to 185 volts in relation to earth between the capacitor the The power consumption at a current was The separator load example that only the power the separation irrespective as to whether the o potential is adjusted by a transforms or apparatus used ia Example 3 and containing only one electrode was used separating a phase containing each of the heavier and lighter phase and tho upper electrode was coated with 2 thick layer of At an voltage of 220 volts and a consumption of 30 a separator load of 16 en eol tioa containing lactic acid it was intended to the latter electrostatic the separator could be loaded with 11 of the heavier of the electrode in eeparator and applying a potential of 25 the rato of throughput at a lower consumption of 360 could be to E insufficientOCRQuality

Claims (1)

1. we A of accelerating into of phase of or sparingly organic or liquids in a liquid a a and a wherein a potential of or applied to at leant one horizontal elootrode in and wherein the supplied to or all electrodes is to 500 of A as claiaed in wherein the power to the is 1 to 100 of in or potential ia the power adjusted by regulation the applied potential by a voltage method as in or wherein the power at a given potential ia of an or a A as in any 1 to wherein when an potential is the is by with electrical Λ method as in a potential is l the power is adjusted by Λ method claimed in one of to wherein the area io to of the sectional of the A aa in wherein the electrode our face area is to of area of the Λ as claimed any ono of Claims 1 to several electrodes are provided to which different potentials are the separator itself or or of the A method as claimed in any one of Claims 1 to wherein only a single conducting electrode the separator casing being earthed an earthed electrode being provided A method as claimed in any ono of Claims 1 to wherein or the current conducting electrode is located at a level which is from to the height of an outlet opening for above the bottom of the A method in Claim wherein the level of 3aid electrode is from to of said method of accelerating the separation into phases of a phaoe mixture substantially aa hereinbefore described reference to the accompanying drawing in any of the foregoing insufficientOCRQuality