Patent GB-722806-A (GB)
Title: Improvements in making unstable separable emulsions
IPC: B01F3/08
Filed: 1951-07-02
Abstract: <PICT:0722806/III/1> <PICT:0722806/III/2> <PICT:0722806/III/3> <PICT:0722806/III/4> In a process which includes the steps of making an unstable emulsion of liquids or vaporous fluids insoluble in one another, which liquids tend to form a stable emulsion with phases reversed from that of the unstable emulsion, and which unstable emulsion is to be subjected to some form of agitation such as centrifuging, the unstable emulsion is formed by feeding the component which tends to form the continuous phase, into the other component in the form of drops or as vapour in the form of vapour bubbles which on condensation form drops, in such a drop size that in the agitation to which the emulsion will subsequently be subjected, no secondary emulsion will be formed.  By secondary emulsion is meant the formation in the dispersed drops of the unstable emulsion of stable emulsions of reverse phase to that of the unstable emulsion. The process is particularly applicable to washing of oils with water where, after the formation of the unstable emulsion, the emulsion is centrifuged to separate the water with the impurities from the purified oil; in such a case no oil is lost with the water or water retained in the oil. Reference is made to washing a kerosene solution of wool grease with water (a water in oil emulsion being stable), by injecting the fatty solution in fine droplets, not exceeding 3m , into the water, and centrifuging the unstable emulsion produced to separate the oil from the water and solid impurities.  Rape seed oil and coconut oil may be similarly treated (an oil in water emulsion being stable in this case) by injecting the water into the oil in drops of 20m  or less for the former and 5m  or less for the latter. The drops size should be decreased depending on the severity of the agitation (pumping, homogenizing, centrifuging) to which the emulsion is to be subjected; particle sizes may be down to 0.1m , the limit being the ability to separate the phases of the emulsion by centrifuging.  The emulsion may be formed in apparatus such as shown in Fig. 1 where oil under pressure is fed through pipe 1 to a nozzle 2, to which water or steam flows from pipe 4 to be injected into nozzles 3.  Alternatively the formation of the emulsion may be associated with a centrifuge as shown in Fig. 3 where a rotating body of liquid 15 is formed in the upper part of a centrifuge bowl 16. The liquid to form the dispersed phase is fed through radial pipes 13 to nozzle 14 and the emulsion formed is collected by the paring disc 11, both the disc 11 and the pipe 13 being static.  As shewn in Fig. 4 a further homogenizing device may be associated with the paring disc; the disperse phase is injected through nozzle 23 and the emulsion formed is caught by a slit 25 on the periphery of the paring disc 20 and is thereby given a tangential movement and is discharged, rapidly rotating, into vessel 21 and withdrawn therefrom by means (not shown).  A further suitable apparatus is shewn in Fig. 5 where one liquid is fed through channel 33 in a static portion 32 to overflow at the top thereof, and the liquid which is to form the disperse phase is fed through a rotating pipe 30 to be discharged through orifices 34 into the vessel 32.