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Title:
SEPARATING A LIQUID PHASE FROM AN EMULSION
Document Type and Number:
WIPO Patent Application WO/2013/162396
Kind Code:
A1
Abstract:
The invention describes a separating assembly (100) for separating a phase from a mixture of an immiscible liquid. The assembly comprises a separation unit (10) with a chamber (11) which is filled with collector particles (50) and through which chamber (50) the immiscible liquid flows, wherein the material of the collector particles (50) is selected from a material so that the phase to be separated from the immiscible liquid wets the surface of the collector particles (50) and wherein the collector particles (50) have a specific weight and/or shape so that their direction of travel within the chamber is dependent from the amount of phase being attached to the collector particles (50). The assembly further comprises an absorber collector unit (20) which is adapted to separate the collector particles (50) from the liquid flow which have gathered or absorbed a sufficient amount of phase to be separated from the liquid in the separation unit (10) so they will be entrained by the liquid flow in the direction of the immiscible liquid flow into the absorber collector unit (20. A phase separator unit (30) receiving the collector particles (50) from the absorber collector unit (20) cleans the collector particles (50) and supplies the cleaned collector particles (50) to the separation unit (10).

Inventors:
MALININ VITALY VLADIMIROVICH (RU)
Application Number:
PCT/RU2012/000316
Publication Date:
October 31, 2013
Filing Date:
April 25, 2012
Export Citation:
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Assignee:
SIEMENS AG (DE)
MALININ VITALY VLADIMIROVICH (RU)
International Classes:
B01D17/02; B01D15/02
Foreign References:
US3215623A1965-11-02
US3674684A1972-07-04
US20110076750A12011-03-31
US5534153A1996-07-09
US20040050769A12004-03-18
EP0148444A21985-07-17
Attorney, Agent or Firm:
LAW FIRM "GORODISSKY & PARTNERS " LTD. (POPOVA Elizaveta VitalievnaB. Spasskaya str., 25, bldg., Moscow 0, RU)
Download PDF:
Claims:
Patent Claims

1. A separating assembly (100) for separating a phase from a mixture of an immiscible liquid, comprising

- a separation unit (10) with a chamber (11) which is

filled with collector particles (50) and through which chamber (50) the immiscible liquid flows, wherein

the material of the collector particles (50) is selected from a material so that the phase to be sepa- rated from the immiscible liquid wets the surface of the collector particles (50) ;

the collector particles (50) have a specific weight and/or shape so that their direction of travel within the chamber is dependent from the amount of phase be- ing attached to the collector particles (50) ; an absorber collector unit (20) which is adapted to separate the collector particles (50) from the liquid flow which have gathered or absorbed a sufficient amount of phase to be separated from the liquid in the separation unit (10) so they will be entrained by the liquid flow in the direction of the immiscible liquid flow into the absorber collector unit (20) ;

a phase separator unit (30) receiving the collector particles (50) from the absorber collector unit (20) for cleaning the collector particles (50) and supplying cleaned collector particles (50) to the separation unit (10) .

2. The separating assembly according to claim 1, wherein the chamber (11) of the separation unit (10) has the shape of a cylinder being vertically aligned.

3. The separating assembly according to claim 1 or 2, wherein the chamber (11) of the separation unit (10) comprises an in- let plate (14) having a number of perforations and being located at a first end of the chamber (11) wherein the immiscible liquid flows through the inlet plate (14) into the chamber (11) .

4. The separating assembly according to claim 3, wherein the collector particles (50) located within the chamber (11) of the separation unit (10) have a diameter being greater than that of the first number of perforations.

5. The separating assembly according to one of the preceding claims, wherein the chamber (11) of the separation unit (10) comprises an outlet being located at a second end opposite to the first end of the chamber (11) wherein the second end is connected to an inlet of the absorber collector unit (20) .

6. The separating assembly according to one of the preceding claims, wherein the absorber collector unit (20) is a gravity separator and/or a cyclone separator and/or a flotation separator.

7. The separating assembly according to one of the preceding claims, wherein the absorber collector unit (20) is adapted to separate the collector particles (50) mechanically from the liquid flow.

8. The separating assembly according to one of the preceding claims, wherein the absorber collector unit (20) is adapted to reduce the velocity of the liquid flow entraining the collector particles (50) so that the wetted collector particles (50) concentrate in the vicinity of an outlet of the absorber collector unit (20) due to their specific weight. 9. The separating assembly according to one of the preceding claims, wherein the phase separator unit (30) is adapted to clean the collector particles (50) mechanically and/or chemically. 10. The separating assembly according to one of the preceding claims, wherein the cleaned collector particles (50) supplied to the separation unit (30) are taken from the phase separa- tor unit (30) or a storage with cleaned collector particles (50) .

11. The separating assembly according to one of the preceding claims, wherein the material of the collector particles (50) is wettable or non-wettable for the phase to be separated from the immiscible liquid, especially hydrophilic or oilphilic . 12. The separating assembly according to one of the preceding claims, wherein the collector particles (50) have different diameters .

13. The separating assembly according to one of the preceding claims, wherein the collector particles (50) have different surface shapes.

Description:
SEPARATING A LIQUID PHASE FROM AN EMULSION

The invention relates to a separating assembly for separating a phase from a mixture of an immiscible liquid.

Mixtures of immiscible liquids are called emulsion. There are a lot of industrial processes encountering the problem of phases' separation from emulsions. For example, the saturation of water-in-oil or oil-in-water emulsions has become industrially important due to increased demands on oil -recovery rates and energy consumption reasons. For example, by the presence of water droplets in liquid fuels corrosion may be caused.

There are so-called primary emulsions with drop sizes greater than 100 microns and so-called secondary emulsions with drop sizes less than 100 microns. The separation of primary emulsions is often accomplished by gravity settling or cyclones. In case of tiny droplets of secondary emulsions with large surface volume ratio standard approaches as named above are not effective. The matter is that so small droplets are com- pletely entrained by main fluid flow of the emulsion. In order to separate secondary emulsions additionally techniques are developed for preliminary coalescence of tiny droplets to larger ones. Coalescence significantly increase droplets' dimensions and make standard separation techniques more effi- cient.

EP 0 148 444 A2 discloses a coalescence filter for separating a phase of an immiscible liquid. In this filter a pre- purified mixture is introduced from below through a perforat- ed plate into the coalescence chamber which contains a multiplicity of coalescence bodies which consist of an oilphilic plastic and are lighter than water. Fine oil particles settle on the oilphilic surface of these bodies, coalesce on the bodies and rise as larger oil droplets, which can easily be separated of, into the separation chamber where they are collected in an oil collection space from which they can be removed .

However, this filter suffers from saturation phenomena. The phase to be separated steadily accumulates on collecting surfaces of the coalescence bodies and remains therefore a sufficient amount of time. Such filter overloading results in an overall decrease of filtration efficiency. This problem can be solved by increase of pressure drop or decrease of mixture flow rate.

Generally, the separation of tiny droplets from liquid emul- sions remains a challenge for industrial applications.

It is therefore an object of the present invention to provide an improved separation assembly which is able to separate droplets of arbitrary size from a liquid emulsion.

This object is solved by a separating assembly according to claim 1. Preferred embodiments are set out in the dependent claims . The invention provides a separating assembly for separating a phase from a mixture of an immiscible liquid. An immiscible liquid is also known as emulsion. The separation assembly comprises : - a separation unit with a chamber which is filled with collector particles and through which chamber the immiscible liquid flows. The material of the collector particles is selected from a material so that the phase to be separated from the immiscible liquid wets the surface of the collec- tor particles. The collector particles have a specific weight and/or shape so that their direction of travel within the chamber is dependent from the amount of phase being attached to the collector particles. As a result, collector particles having no wetted surface move against the direction of the immiscible liquid flow. On the other hand, the collector particles having a surface being saturated or wetted with sufficient amount of the phase to be separated move in the direction of the immiscible liquid flow. an absorber collector unit which is adapted to separate the collector particles from the liquid flow which have gathered or absorbed a sufficient amount of phase to be separated from the liquid in the separation unit so they will be entrained by the liquid flow in the direction of the immiscible liquid flow into the absorber collector unit . a phase separator unit receiving the collector particles from the absorber collector unit for cleaning the collector particles and supplying cleaned collector particles to the separation unit.

The separating assembly according to the invention has no loss of absorber material, i.e. the collector particles, since they move between the three units in a "closed circulation" . Due to the phase separator unit which ensures cleaning the collector particles so that collector particles with maximum of absorbance properties can be supplied to the separation unit, a high efficiency of the separation assembly is provided. Additionally, the separation assembly provides big flexibility since an easy adjustment to the flow velocity and/or consistency is possible.

According to a further embodiment the chamber has the shape of a cylinder being vertically aligned such that the immiscible liquid flows from an inlet to an outlet. It is to be un- derstood that the geometry of the chamber may differ as long as this geometry allows a stable flow of the liquid. In particular, the flow direction is parallel to a gravity force vector. Generally, the flow direction depends on the properties of the phase to be separated.

According to a further embodiment the chamber of the separa- tion unit comprises an inlet plate having a number of perforations and being located at a first end of the chamber wherein the immiscible liquid flows through the inlet plate into the chamber. Preferably, the collector particles located within the chamber of the separation unit have a diameter be- ing greater than that of the number of perforations.

According to a further embodiment the chamber of the separation unit comprises an outlet being located at a second end opposite to the first end of the chamber wherein the second end is connected to an inlet of the absorber collector unit.

According to a further embodiment the absorber collector unit is a gravity separator and/or a cyclone separator and/or a flotation separator. Preferably, the absorber collector unit is adapted to separate the collector particles mechanically from the liquid flow. However, it is to be understood that any technology may be used to separate the collector particles from the liquid flow. According to a further embodiment the absorber collector unit is adapted to reduce the velocity of the liquid flow entraining the collector particles so that the wetted collector particles concentrate in the vicinity of an outlet of the absorber collector unit due to their specific weight. This em- bodiment makes use of the physical properties of the wetted collector particles such that they have a preferred direction of movement in a liquid which has a very slow velocity. At the end of the preferred direction of movement the outlet of the absorber collector is arranged for supplying them to the phase separator unit.

According to a further embodiment the phase separator unit is adapted to clean the collector particles mechanically and/or chemically. This may be done by using a centrifuge. However, other systems and technologies may be used to clean the collector particles from phase to be separated. According to a further embodiment the cleaned collector particles supplied to the separation unit are taken from the phase separator unit or a storage with cleaned collector particles. The separating assembly enables exchanging the collector particles, for instance to adapt them in best possible way to the properties of the immiscible liquid. Exchanging the collector particles may be useful, if the composition of the immiscible liquid changes during operation of the separator assembly. According to a further embodiment the material of the collector particles is wettable or non-wettable for the phase to be separated from the immiscible liquid. In particular the material may be hydrophilic or oilphilic. According to a further embodiment the collector particles which are used concurrently in the separation unit have different diameters. The collector particles which are used concurrently in the separation unit may additionally or alternatively have different surface shapes. As a result, independ- ent from the composition of the immiscible liquid there are collector particles within the separation unit that are able to collect phase to be separated in an efficient manner.

The invention will be described hereinafter in more detail by reference to the accompanying figures.

Fig. 1 shows a first embodiment of a separating assembly according to the invention. Fig. 2 shows a second embodiment of a separating assembly according to the invention. Fig. 3 shows a schematic view of a separating assembly according to the invention.

Referring to Fig. 1 and 2, a separating assembly 1 consists of a separation unit 10, an absorber collection unit 20 and a phase separation unit 30. The separation unit 10 consists of a vertically aligned cylindrical chamber 11 which is filled with collector particles 50. "Vertically aligned" means that the orientation of the chamber 11 is substantially parallel to a gravity field vector G. The shape of the chamber 11 in cross section does not necessarily have to have the shape of a circle. In cross section the chamber 11 could have any other suitable shape. The collector particles 50 are, for example, hydrophobic

(Fig. 1) or hydrophilic (Fig. 2) spherical particles of an arbitrary diameter and/or shape. The diameter and/or shape depends on operational conditions as will be explained later on. The material of the collector particles 50 depends on the phase to be separated from an immiscible liquid flowing parallel to the gravity force vector G through the chamber 11. Therefore, in general, the material is wettable or non- wettable for the phase to be separated from the immiscible liquid.

From an inlet 12 the chamber 11 is sealed with a perforated plate 14. The shape and size, respectively, of the perforations (not shown) is such that their diameter is smaller than the diameter of the collector particles 50. As a result, the perforated plate 14 which encloses the chamber 11 at their inlet 12 restricts the collector particles 50 from escaping the chamber 11.

The principle operation of the separation unit 10 is based on a selected wetting of the phase to be separated on the surface of the collector particles 50. For example, in case of oil to be separated from a water-oil -emulsion (cf. Fig. 1) the collector particles 50 should be made of hydrophobic or oilphilic material. In the opposite case of water to be separated from an oil-water-emulsion (cf. Fig. 2), the collector particles 13 should be hydrophilic or oilphobic. In case of the situation of Fig. 1 droplets of the lighter phase have to be separated from the main carrying fluid, i.e. the emulsion. In this situation the fluid flow Fl is directed upward and the collector particles 50 have a negative floatage in respect to the main carrying fluid (emulsion) . A nega- tive floatage means that such a particle has a greater than carrying fluid density and tends to sink down in steady fluid. As mentioned, plate 14 acts as a fluid inlet plate at the bottom of the chamber 11 while an outlet 13 of the chamber 11 is at the upper end of chamber 11. Characterizing for this situation is that the fluid flow Fl is in the opposite direction to the gravity field vector G.

In the second situation (illustrated in Fig. 2) droplets of denser phase than the main carrying fluid have to be separat- ed. In this situation the fluid flow Fl is directed downwards, i.e. in the direction of the gravity field vector G. The collector particles 50 have a positive floatage in respect to the main carrying fluid. A positive floatage means that such a particle has a smaller than main carrying fluid density and tends to rise up in steady fluid. In this situation the inlet plate 14 is - with regard to the gravity field vector - at the upper end of the chamber 11 while the outlet 13 of the chamber 11 is at the lower end of chamber 11. During mixture flow of the emulsion through the separation unit 10, dispersed phase droplets adsorption occurs at the surface of the collector particles 50. Having reached sufficient "load" of dispersed phase the given sphere (i.e. the surface of the collector particle) is entrained by the fluid flow. In case of the lighter phase separation they rise up toward the outlet 13 of the chamber 11 (Fig. 1) . In case of the separation of a denser phase than the main carrying fluid the collector particles sink down towards the outlet 13 of the chamber 11 (Fig. 2) .

In Fig. 1 and 2 collector particles 50 which are not wetted with a phase to be separated are depicted with reference numeral 51. Collector particles 50 which are wetted with an amount of phase to be separated being not sufficient not to be entrained by the fluid flow are depicted with reference numeral 52. Collector particles 50 which are saturated or wetted with an sufficient amount of phase to be separated from the emulsion so that they will be entrained by the fluid flow are depicted with reference numeral 53.

The outlet 13 of the chamber 11 of the separation unit 10 is connected to an inlet 21 of the absorber collector unit 20 which is just shown schematically. The connection may be made by a conduit. Alternatively, the inlet 21 may be connected directly to the outlet 23. The absorber collector unit 20 may be of an arbitrary design. It may be realized, for example, as a gravity separator and/or a cyclone separator and/or a flotation separator. In the absorber collector unit 20 the collector particles 53 enriched with the dispersed phase are separated from main fluid and then supplied via a first outlet 22 to a phase separator unit 30 (cf. CP) while the

"cleaned" fluid flow LF is led to a second outlet 23.

The velocity of the fluid flow LF+CP may be reduced within the absorber collector unit 20 so that the wetted collector particles 53 concentrate in the vicinity of the outlet 23 of the absorber collector unit 20 due to their specific weight. Depending on the phase to be separated the outlet 23 may be located (with regard to the gravity field vector G) at the bottom of the absorber collector unit 20. In the phase separator unit 30 the collector particles 50 enriched with the dispersed phase are cleaned. Cleaning may be made with an arbitrary design of convenient techniques. For example, cleaning may be made mechanically or chemically. Fi- nally the cleaned collector particles 50 are returned back to separation unit 10 (cf . reference numeral CP) .

In an alternative embodiment the cleaned collector particles could be stored and collector particles from the storage could be returned to the separation unit 10. In this case collector particles of different diameter and/or surface shape could be taken which is adapted to the properties of the immiscible fluid in best way.

Generally, in the separation unit 10 collector particles 50 of the same shape and diameter may be used. However, the collector particles 50 used concurrently in the chamber 11 of the separation unit 10 may be of different shape and/or diam- eter to provide more flexibility with respect to the composition of the immiscible liquid.

Fig. 3 illustrates the working principle of the above described separating assembly in a schematic view. The mixture of immiscible liquid LF flows through the separation unit 10 filled with the collector particles having properties as described above. Those of the collector particles being enriched with phase to be separated are entrained by the fluid flow (LF+CP) towards the absorber collector 20. "Cleaned" fluid LFc leaves the absorber collector 20 without the enriched collector particles CP. The latter are supplied to the phase separator unit 30 for cleaning. Cleaned collector particles CP C are supplied to the separation unit 10 again. In the separation unit 10, an additional negative or positive floatage might be forced to determine an amount of adsorbed dispersed phase sufficient to force spherical collector particle entrainment by fluid flow Fl . Controlling negative or positive floatage allows to select an optimal absorber recir- culation rate in order to minimize costs associated with particles cleaning. At the same time sufficient "load" of absorbed phase allows to avoid completely a loss of absorber material, i.e. collector particles. From another side large particle floatage implies larger diameter value. In its turn larger diameter decreases an absorber particles packing fraction (effective surface) de- creasing separation efficiency. So there is an extremum for an absorber particle diameter providing maximal performance characteristics. This extremum can be determined by computing or testing. Due to the principle of above described operation a collector particle load has a permanent value. This allows performing a fine-tuning of auxiliary cleaning equipment to this value within the phase separator unit. Such tuning results in sufficient improvement of an overall performance of the separat- ing assembly.

The proposed design provides the possibility to use simultaneously packs of spheres (collector particles) of different diameter and different surface properties. The application of such mixed packs allows to increase separation selectivity significantly without or by the cost of minor increase in pressure drop. Moreover it is possible to change absorber particles diameter, floatage and surface properties during the operation of the separating assembly.

The proposed separating assembly has a number of further advantages :

The proposed design of separation unit allows to separate any types of immiscible fluids.

There are no limitations on minimal possible diameter of dispersed phase droplets. Furthermore, there are no limitations on the composition of the immiscible liquid.

The proposed design does not suffer from separated phase saturation or contamination due to periodic cleaning of the collector particles. There is no loss of absorber material, i.e. the collector particles, during the whole operation time. Flexibility in response to dispersed phase properties variation.