TECHNICAL FIELD OF THE INVENTION

This invention relates to the separation of liquid two-phase dispersions into phases and may be used in the chemical, food, and microbiological industries. PRIOR ART OF THE INVENTION

Common examples of liquid two-phase dispersions are emulsions. Emulsions are colloidal systems, in which a finely dispersed liquid constituting a dispersed phase is distributed in another liquid referred to as a dispersion medium.

Two major types of emulsions are identified. The first type includes oil-in-water emulsions in which the dispersion medium is a hydrophilic liquid (water) with hydrophobic liquid (oil) particles as the dispersed phase. The second type includes water-in-oil emulsions in which the dispersion medium is a hydrophobic liquid (oil) and the dispersed phase is a finely dispersed hydrophilic liquid (water). Various methods are used for emulsion breaking into their constituent phases subject to the nature and stability of an emulsion.

The most widely used are gravity separation methods based on the emulsion constituent phases' density difference. They primarily include the methods based on settling and centrifuging (Chemist's Guide 21 . Emulsions, Separation. 2015. http://chem21 /info/394402/; Tetra Pak Dairy Processing Handbook. Centrifugal separation and milk standardization. http://www.dairyprocessinghandbook.com/chapter/ centrifugal-separators-and- milk-standardization).

However, the settling method, in which the dispersed phase particles spontaneously coalesce to form an individual macrophase (mass) readily separable, for example, via decantation, is an extremely slow batch, and, therefore, low efficiency process.

Known is a method for separating water based emulsions, including an organic light dispersion phase in the form of finely dispersed crude oil, petroleum products, fats, etc., by a centrifuge comprising a rotating rotor and a coalescing cell (RU 2545555 C1 , published 10.04.2015).

Centrifuging, particularly at high acceleration, is a much more efficient method. However, high speed centrifuges are energy intensive complex devices requiring continuous expert maintenance.

A key factor responsible for the specifics of centrifuging as an emulsion breaking method is a relatively high viscosity of the dispersion phase, which is characteristic of liquids. This results in significant hydrodynamic resistance to the motion of the dispersed phase particles, thus slowing down the process of the dispersed phase separation from the continuous dispersion medium.

Further, centrifuging does not always produce the desired result, particularly, due to the formation of a hardly separable layer at the phase boundary requiring either re-centrifuging to destabilize it, or use of special agents to prevent formation of such layer. Examples of industrial scale emulsion braking by high-speed centrifuging (separation) are such well known processes as milk separation, organosilicon fluid dehydrating method, crude oil emulsion breaking method, and the natural latex concentration process.

SUMMARY OF THE I NVENTION The objective of the present invention is to provide a general-purpose emulsion breaking method which features improved efficiency of phase separation while reducing energy consumption for the process.

This objective is achieved through a method for emulsion breaking by subjecting an emulsion to centrifugal forces and separate draining of the emulsion constituent phases, which method comprises, according to this invention: first transforming an emulsion into an aerosol with a gas as the dispersion medium and particles of the dispersion medium and dispersed phase of the initial emulsion as the dispersed phase, and then subjecting the resulting aerosol to centrifugal forces. The method may be used to break the first type emulsions or the second type emulsions, wherein the first type includes oil-in-water emulsions in which the dispersion medium is a hydrophilic liquid (water) with hydrophobic liquid (oil) particles as the dispersed phase and the second type includes water-in-oil emulsions in which the dispersion medium is a hydrophobic liquid (oil) and the dispersed phase is a finely dispersed hydrophilic liquid (water). Emulsion may be aerosolized by hydraulic, or pneumatic, or ultrasonic atomizing in a gas medium.

Air, or an inert gas, or nitrogen, may be used as the gas medium.

Aerosol produced by atomizing an emulsion is substantially a colloidal system, comprised by at least two types of particles of different nature, dispersed in a gas medium and featuring widely different densities. Since viscosity of the gas (air) medium, in which such particles are contained, is relatively low as compared to the liquid, they may be separated from each other by gravity methods, including centrifuging, much more efficiently.

DETAILED DESCRIPTION OF THE INVENTION The present invention, method for emulsion breaking comprises following steps: atomizing the emulsion, delivering the emulsion to a gas centrifuge, separating the organic and the water from the gas medium, draining the organic phase and the water phase from the centrifuge, collecting the phases in separate collecting tanks, delivering the air to the ultrasonic disperser for reuse. The objective of separating dispersed particles of different nature, contained in an aerosol, may be achieved through using gas centrifuges, including those employing the method of gas centrifuging in a porous medium. The latter are relatively simple devices that are significantly less energy intensive than conventional liquid centrifuges and separators and allow addressing both the challenge of separating the particles from the gas and that of separating the particles from each other.

Gas centrifuges are successfully used for associated gas treatment in the petroleum industry and feature high performance and relatively low energy consumption. Both first type and second type emulsions may be transformed into aerosols by various methods: ultrasonic liquid dispersers, hydraulic and pneumatic atomizers.

Based on the emulsion properties and the nature of the phase-forming components, as well as the dispersion method, aerosol particle diameter may reach approximately 0.1 micron with rather narrow size and mass distribution.

The process may be carried out at any temperature higher than freezing points and lower than boiling points of emulsion components.

Below are examples illustrating the essence of alternative embodiments of the proposed invention.

Example 1 .

A water-in-oil emulsion (Type 2 emulsion) with a water phase to organic phase ratio of 1 :3 was atomized in a flow of air at a pressure of 10 MPa by an ultrasonic disperser to produce an aerosol containing finely dispersed water and crude oil particles. The resulting aerosol was delivered to a gas centrifuge, where the organic and the water phases were separated from the gas medium. The organic phase and the water phase were then drained from the centrifuge and were collected in separate collecting tanks, while air was delivered to the ultrasonic disperser for reuse. Example 2.

Same as in Example 1 , but differing in that the system to be separated was milk with a fat content of 3.5% (Type 1 emulsion), air atomized at a pressure of 0.2 MPa via a hydraulic atomizer with an outlet diameter of 0.1 mm. As a result of centrifuging, a hydrophilic liquid phase (skim milk) with a fat content of 0.3% and a hydrophobic (fat) phase with a fat content of approximately 30% were produced.

The proposed method is applicable to any types of emulsions with different components.

Industrial Applicability The proposed method for emulsion breaking may be used in the chemical, food, and microbiological industries, in particular, for milk separation, organosilicon fluid dehydration, crude oil emulsion breaking, natural latex concentration, using the existing industrial equipment.