WO2013045918A1

WO2013045918A1 - Apparatus for particle production

Info

Publication number: WO2013045918A1
Application number: PCT/GB2012/052382
Authority: WO
Inventors: Richard HOLDICH
Original assignee: MICROPORE TECHNOLOGIES Ltd
Current assignee: MICROPORE TECHNOLOGIES Ltd
Priority date: 2011-09-26
Filing date: 2012-09-26
Publication date: 2013-04-04
Anticipated expiration: 2014-03-26
Also published as: GB201116553D0; GB2494926A; GB2494926B

Abstract

An apparatus for particle production, the apparatus comprising: a membrane (16) defining a plurality of apertures (36) and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures to form an emulsion; and a first reactor (24) configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion, the reactor comprising a plurality of connected reactor chambers (42).

Description

TITLE

Apparatus for particle production TECHNOLOGICAL FIELD

Embodiments of the present invention relate to an apparatus for particle production. BACKGROUND

Apparatus for particle production may include a membrane in which a dispersed phase is introduced to a continuous phase to form an emulsion. The emulsion may then be passed to a stirring tank for solidification and subsequently to a filter for filtering the dispersed phase particles from the continuous phase. However, the particles produced by such an apparatus may be relatively small and have a broad distribution of sizes.

It would therefore be desirable to provide an alternative apparatus for particle production.

BRIEF SUMMARY

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus for particle production, the apparatus comprising: a membrane defining a plurality of apertures and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures to form an emulsion; and a first reactor configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion, the first reactor comprising a plurality of connected reactor chambers. A reactor chamber of the plurality of reactor chambers may include an inlet aperture, an outlet aperture and a cavity there between, a cross sectional area of the cavity being greater than a cross sectional area of the inlet aperture and the outlet aperture.

The membrane may be substantially tubular in shape and may have a first end defining a first aperture for receiving the first liquid phase and a second end defining a second aperture for providing the emulsion. The apparatus may further comprise an actuator for oscillating liquid flow over the membrane and within the first reactor.

The actuator may be configured to oscillate liquid flow over the membrane and within the first reactor at a frequency in the range of one Hertz to ten Hertz and with an amplitude in the range of 500 micrometres to two millimetres.

A third liquid phase, miscible with the first liquid phase, may be provided to the emulsion prior to the emulsion being received at the first reactor.

The apparatus may further comprise a second reactor configured to receive the emulsion from the first reactor and at least partially solidify the droplets of the second liquid phase in the emulsion. The apparatus may further comprise a filter for filtering the droplets of the second liquid phase from the first liquid phase.

According to various, but not necessarily all, embodiments of the invention there is provided a method of particle production, the method comprising: controlling provision of a first liquid phase to a membrane, the membrane defining a plurality of apertures, and controlling provision of a second liquid phase to the membrane via the plurality of apertures to form an emulsion, a first reactor being configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion, the first reactor comprising a plurality of connected reactor chambers. A reactor chamber of the plurality of reactor chambers may include an inlet aperture, an outlet aperture and a cavity there between, a cross sectional area of the cavity being greater than a cross sectional area of the inlet aperture and the outlet aperture. The membrane may be substantially tubular in shape and may have a first end defining a first aperture for receiving the first liquid phase and a second end defining a second aperture for providing the emulsion.

The method may further comprise controlling oscillation of liquid flow over the membrane and the first reactor.

The oscillation of liquid flow in the membrane and the first reactor may be at a frequency in the range of one Hertz to ten Hertz and with an amplitude in the range of 500 micrometres to two millimetres.

The method may further comprise controlling provision of a third liquid phase, miscible with the first liquid phase, to the emulsion prior to the emulsion being received at the first reactor. The method may further comprise controlling a second reactor to at least partially solidify the droplets of the second liquid phase in the emulsion.

A filter may be configured to filter the droplets of the second liquid phase from the first liquid phase.

According to various, but not necessarily all, embodiments of the invention there is provided a non-transitory computer-readable storage medium encoded with instructions that, when performed by a processor, cause performance of: the method described in any of the preceding paragraphs.

According to various, but not necessarily all, embodiments of the invention there is provided a computer program that, when run on a computer, performs the method described in any of the preceding paragraphs.

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus for particle production, the apparatus comprising: a membrane defining a plurality of apertures and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures to form an emulsion; a first reactor configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion; and an actuator for oscillating liquid flow in the membrane and the first reactor.

BRIEF DESCRIPTION

For a better understanding of various examples of embodiments of the present invention reference will now be made by way of example only to the accompanying drawings in which:

Fig. 1 illustrates a schematic diagram of an apparatus for particle production according to various embodiments of the invention;

Fig. 2 illustrates an enlarged cross sectional side view of the first reactor illustrated in fig. 1 ; and

Fig. 3 illustrates a flow diagram of a method for controlling an apparatus for particle production according to various embodiments of the invention.

DETAILED DESCRIPTION In the following description, the wording 'connect' and 'couple' and their derivatives mean operationally connected or coupled. It should be appreciated that any number or combination of intervening components can exist (including no intervening components).

Figure 1 illustrates an apparatus 10 for particle production, the apparatus 10 comprising: a membrane 16 defining a plurality of apertures 36 and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures 36 to form an emulsion; and a first reactor 24 configured to receive the emulsion from the membrane 16 and to at least partially solidify droplets of the second liquid phase in the emulsion, the first reactor 24 comprising a plurality of connected reactor chambers 42. In more detail, fig .1 illustrates an apparatus 10 for particle production according to various embodiments of the invention. The apparatus 10 includes a controller 12, a memory 14, a membrane 16, a first container and pump 18 for a first liquid phase, a second container and pump 20 for a second liquid phase, (optionally) a third container and pump 22 for a third liquid phase, a first reactor 24, an actuator 26, a second reactor 28 and a filter 30.

In general, the apparatus 10 is configured to produce particles by forming an emulsion from a first liquid phase, a second liquid phase and (optionally) a third liquid phase, solidifying the particles in the emulsion, and then filtering the particles from the emulsion. The particles may be used for a wide variety of applications and may be used, for example, as food and flavouring encapsulated (controlled release) products and in ion exchange resins and chromatography (where the particles are polymerised styrene or a similar monomer material).

The implementation of the controller 12 can be in hardware alone (e.g. a circuit, a processor etc), have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware). The controller 12 may be implemented using instructions that enable hardware functionality, for example, by using executable computer program instructions in a general-purpose or special-purpose processor that may be stored on a computer readable storage medium (disk, memory etc) to be executed by such a processor.

The controller 12 is configured to read from and write to the memory 14. The controller 12 comprises an output interface via which data and/or commands are output by the controller 12 and may also comprise an input interface via which data and/or commands are input to the controller 12. The controller 12 is configured to control the first pump 18, the second pump 20, the third pump 22, the actuator 26 and the second reactor 28. The memory 14 stores a computer program 32 comprising computer program instructions that control the operation of the apparatus 10 when loaded into the controller 12. The computer program instructions 32 provide the logic and routines that enables the apparatus 10 to perform the methods illustrated in Fig. 3 and described in the following paragraphs. The controller 12 by reading the memory 14 is able to load and execute the computer program 32.

The computer program 32 may arrive at the apparatus 10 via any suitable delivery mechanism 34. The delivery mechanism 34 may be, for example, a non-transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a compact disc readonly memory (CD-ROM) or digital versatile disc (DVD), an article of manufacture that tangibly embodies the computer program 32. The delivery mechanism may be a signal configured to reliably transfer the computer program 32. The apparatus 10 may propagate or transmit the computer program 32 as a computer data signal. Although the memory 14 is illustrated as a single component it may be implemented as one or more separate components some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/ dynamic/cached storage.

References to 'computer-readable storage medium', 'computer program product', 'tangibly embodied computer program' etc. or a 'controller', 'computer', 'processor' etc. should be understood to encompass not only computers having different architectures such as single /multi- processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

The membrane 16 may be any suitable membrane that is configured to form an emulsion from a first liquid phase and a second liquid phase. The membrane 16 defines a plurality of apertures 36 that may be through-holes or may be apertures that have a tortuous path. The plurality of apertures 36 may have any suitable shape and dimensions and may be sized in the range of micrometres (e.g. 0.1 micrometres to 100 micrometres). The plurality of apertures 36 are configured to enable the second liquid phase (provided by the second container and pump 20) to pass there through and into the first liquid phase.

In this embodiment, the membrane 16 defines a substantially hollow tube and has a first end 38 defining a first aperture for receiving the first liquid phase and a second end 40 defining a second aperture for providing the emulsion. The plurality of apertures 36 are defined on the curved wall of the hollow tube membrane 16.

The first reactor 24 is illustrated in cross section in figs. 1 and 2 and may be any suitable plug flow reactor that is configured to receive the emulsion from the membrane 16 and to at least partially solidify droplets of the second liquid phase in the emulsion. The first reactor 24 is connected to the membrane 16 and may be directly connected (with no intervening elements) in some embodiments or may be indirectly connected (i.e. with one or more intervening elements between the first reactor 24 and the membrane 16) in other embodiments. Consequently, the membrane 16 and the first reactor 24 are an integral apparatus and may be manufactured and sold as a single unit. The first reactor 24 comprises a plurality of reactor chambers 42 that are connected in series between an inlet 44 and an outlet 46. The inlet 44 is connected to the second end 40 of the membrane 16 and consequently, the emulsion generated by the membrane 16 may flow to the plurality of reactor chambers 42.

The first reactor 24 defines a cavity 48 around the plurality of reactor chambers 42 and includes apertures for enabling a fluid 50 (e.g. water) to pass there through. The plurality of reactor chambers 42 and the cavity 48 share an interface via which heat energy may be transferred between the emulsion and the fluid 50. In various embodiments, the controller 12 is configured to control the temperature of the fluid 50 and thereby control the solidification of the droplets of the second liquid phase in the first reactor 24.

At least some reactor chambers of the plurality of reactor chambers 42 include an inlet aperture 52, an outlet aperture 54 and a cavity 56 there between. Opposing walls of the cavity 56 follow a roughly parabolic shape between the inlet aperture 52 and the outlet aperture 54 and have a maximum cross sectional area approximately halfway between the inlet aperture 52 and the outlet aperture 54. Consequently, the cavity 56 is roughly elliptical when viewed in cross section and the walls of the cavity 56 extend both radially and axially around the inlet and outlet apertures 52, 54. It should be appreciated that the apertures 52, 54 form 'bottle necks' between the plurality of reactor chambers 42 and a cross sectional area of the cavity 56 is greater than the cross sectional areas of the inlet aperture 52 and the outlet aperture 54.

The actuator 26 may be any suitable device for oscillating the liquid phases within the membrane 16 and the first reactor 24 and may be a piston for example. The actuator 26 is configured to oscillate/pulsate the liquid phases along the longitudinal axes of the membrane 16 and the first reactor 24 (i.e. left and right in fig. 1 ). In various embodiments, the actuator 26 may oscillate the liquid flow in the membrane 16 and the first reactor 24 at a frequency in the range of 1 to 10 Hz and with an amplitude in the range of 0.5 to 2 mm.

The second reactor 28 is configured to receive the emulsion from the first reactor 24 and to at least partially further solidify the droplets of the second liquid phase in the emulsion. In various embodiments, the second reactor 28 is a stirring tank reactor.

The filter 30 is configured to receive the emulsion from the second reactor 28 and to filter the solidified droplets (i.e. the formed particles) of the second liquid phase from the emulsion. The filter 30 may include a device for washing the particles after they have been filtered from the emulsion. The continuous phase of the filtered emulsion may be recycled for later use. The operation of the apparatus 10 will now be described with reference to figs. 1 , 2 and 3.

At block 58 of fig. 3, the controller 12 controls the pump 18 to provide the first liquid phase to the aperture at the first end 38 of the membrane 16.

At block 60 of fig. 3, the controller 12 controls the pump 20 to provide the second liquid phase to membrane 16 to form an emulsion inside the membrane 16. In various embodiments, the membrane 16 is provided within a sealed container (such as a shroud) and the pump 20 pumps the second liquid phase into the sealed container.

As the second liquid phase ingresses into the membrane 16 via the plurality of apertures 36, the flow of the first liquid phase within the membrane 16 causes shear and removes droplets of the second liquid phase and thus forms an emulsion within the membrane 16 where the first liquid phase is a continuous phase and the second liquid phase is a dispersed phase. Due to the pressure provided by the flow of liquid from the first and second pumps 18, 20, the formed emulsion flows into the first reactor 24 where it flows from the inlet aperture 44 to the outlet aperture 46 in plug flow due to the arrangement of the plurality of chambers 42. The flow of liquid 50 through the first reactor 24 may result in heat energy transfer between the liquid 50 and the emulsion in the plurality of chambers 50. The transfer of the heat energy causes the second liquid phase droplets in the emulsion to at least partially solidify and form particles in the emulsion. In some embodiments, the controller 12 controls the variation in the temperature of the liquid 50 so that as the particles are formed in the emulsion, the heat transfer between the liquid 50 and the emulsion is optimal. For example, some particles become exothermic as they form and the controller 12 may reduce the temperature of the liquid 50 so that heat energy generated by the formation of the particles is transferred to the liquid 50.

At block 62, the controller 12 controls the actuator 26 to oscillate/pulse the flow of the liquid phases within the membrane 16 and the first reactor 24. This oscillation increases the shear between the first liquid phase and the second liquid phase within the stationary membrane 16 and advantageously increases the formation of second liquid phase droplets within the emulsion. Furthermore, this oscillation increases uniform flow of the emulsion within the first reactor 24. Additionally, where the cavities 56 of the plurality of chambers 42 have walls that extend radially and axially, the oscillation causes the second liquid phase droplets to move radially and axially (due to deflections at the walls) and increases mixing of the droplets within the emulsion. This increased mixing is advantageous since it may result in efficient heat transfer between the liquid 50 and the second liquid phase droplets in the emulsion. At (optional) block 64, the controller 12 controls the third pump 22 to provide a third liquid phase (which is miscible with the first liquid phase) to the emulsion prior to the emulsion being received at the first reactor 24. The third liquid phase may be a continuous phase such gum Arabic 2% solution that facilitates solidification of the second liquid phase droplets.

At block 66, the controller 12 controls the second reactor 28 to at least partially further solidify the droplets of the second liquid phase in the emulsion. For example, where the second reactor 28 is a stirring tank, the controller 12 may control the frequency at which the emulsion is stirred. The emulsion is then passed from the second reactor 28 to the filter 30 where the formed particles are filtered off from the emulsion.

Embodiments of the present invention provide several advantages. Firstly, the first reactor 24 provides an environment for the emulsion where the second liquid phase droplets may solidify in the emulsion with a reduced risk of being broken up (when compared to a stirring tank for example). This may advantageously result in the second liquid phase droplets having consistent dimensions and the emulsion having a relatively high concentration of second liquid phase droplets.

Secondly, the apparatus 10 may enable 'continuous' particle production since it may not require user intervention for the particles to be produced. Consequently, the apparatus 10 may be relatively low in cost to operate since it may not require significant human intervention.

Thirdly, since the apparatus 10 may be an enclosed system, there may be no contamination of the emulsion from outside until after the particles have been formed. This may advantageously result in the particles having a relatively pure chemical composition which is substantially free of contaminants.

Fourthly, the first reactor 24 may enable a high level of temperature control of the emulsion and this may be particularly helpful for the production of particles from droplets where there is a sensitive (or dangerous) region during the reaction (e.g. during suspension polymerisation of certain monomers, e.g. styrene).

In one example application of embodiments of the present invention, polymerisation of styrene (as an example of a monomer) may be achieved in the first reactor 24 by providing the fluid 50 at a temperature between 80 and 90 Celsius and maintaining that temperature for a predetermined residence time within the first reactor 24. At the end of that stage, the temperature of the fluid 50 is reduced to remove heat from the exothermic reaction of the particles.

In another example application, the apparatus 10 may be operated to encapsulate particles by means of complex coacervation. The apparatus 10 facilitates the production of coacervates continuously by generating the essential and vegetable oil droplets in the membrane tube at 40 Celsius, using a gelatine aqueous solution as the continuous phase into which the oil phase is dispersed followed by injection of another aqueous phase containing gum Arabic between the membrane 16 and the first reactor 24. The emulsion enters the first reactor 16 and is cooled in a controlled way from 40 Celsius to 15 Celsius using the fluid 50 in counter current flow to the emulsion.

The blocks illustrated in the Fig. 3 may represent steps in a method and/or sections of code in the computer program 32. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, in some embodiments, the apparatus 10 may not include a controller 12 and a memory 14, and in these embodiments, the various components of the apparatus 10 may be controlled by a human operator.

In some embodiments, the plurality of chambers 42 of the first reactor 24 may have a different shape and may be square or rectangular in cross section for example.

In some embodiments, the first reactor 24 may not include a plurality of chambers 42 and may be any reactor connected to the membrane 16 for at least partially solidifying the second liquid phase droplets in the emulsion.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be perfornnable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

I/we claim:

Claims

1 . An apparatus for particle production, the apparatus comprising:

a membrane defining a plurality of apertures and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures to form an emulsion; and

a first reactor configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion, the first reactor comprising a plurality of connected reactor chambers.

2. An apparatus as claimed in claim 1 , wherein a reactor chamber of the plurality of reactor chambers includes an inlet aperture, an outlet aperture and a cavity there between, a cross sectional area of the cavity being greater than a cross sectional area of the inlet aperture and the outlet aperture.

3. An apparatus as claimed in claim 1 or 2, wherein the membrane is substantially tubular in shape and has a first end defining a first aperture for receiving the first liquid phase and a second end defining a second aperture for providing the emulsion.

4. An apparatus as claimed in any of the preceding claims, further comprising an actuator for oscillating liquid flow over the membrane and within the first reactor.

5. An apparatus as claimed in claim 4, wherein the actuator is configured to oscillate liquid flow over the membrane and within the first reactor at a frequency in the range of one Hertz to ten Hertz and with an amplitude in the range of 500 micrometres to two millimetres.

6. An apparatus as claimed in any of the preceding claims, wherein a third liquid phase, miscible with the first liquid phase, is provided to the emulsion prior to the emulsion being received at the first reactor.

7. An apparatus as claimed in any of the preceding claims, further comprising a second reactor configured to receive the emulsion from the first reactor and at least partially solidify the droplets of the second liquid phase in the emulsion.

8. An apparatus as claimed in any of the preceding claims, further comprising a filter for filtering the droplets of the second liquid phase from the first liquid phase.

9. An apparatus substantially as hereinbefore described with reference to and/or as shown in the accompanying figures.

10. A method of particle production, the method comprising:

controlling provision of a first liquid phase to a membrane, the membrane defining a plurality of apertures, and

controlling provision of a second liquid phase to the membrane via the plurality of apertures to form an emulsion, a first reactor being configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion, the first reactor comprising a plurality of connected reactor chambers.

1 1 . A method as claimed in claim 10, wherein a reactor chamber of the plurality of reactor chambers includes an inlet aperture, an outlet aperture and a cavity there between, a cross sectional area of the cavity being greater than a cross sectional area of the inlet aperture and the outlet aperture.

12. A method as claimed in claim 10 or 1 1 , wherein the membrane is substantially tubular in shape and has a first end defining a first aperture for receiving the first liquid phase and a second end defining a second aperture for providing the emulsion.

13. A method as claimed in any of claims 10 to 12, further comprising controlling oscillation of liquid flow over the membrane and the first reactor.

14. A method as claimed in claim 13, wherein the oscillation of liquid flow in the membrane and the first reactor is at a frequency in the range of one Hertz to ten Hertz and with an amplitude in the range of 500 micrometres to two millimetres.

15. A method as claimed in any of claims 10 to 14, further comprising controlling provision of a third liquid phase, miscible with the first liquid phase, to the emulsion prior to the emulsion being received at the first reactor.

16. A method as claimed in any of claims 10 to 15, further comprising controlling a second reactor to at least partially solidify the droplets of the second liquid phase in the emulsion.

17. A method as claimed in any of claims 10 to 16, wherein a filter is configured to filter the droplets of the second liquid phase from the first liquid phase.

18. A method substantially as hereinbefore described with reference to and/or as shown in the accompanying figures.

19. A non-transitory computer-readable storage medium encoded with instructions that, when performed by a processor, cause performance of: the method of any of claims 10 to 18.

20. A computer program that, when run on a computer, performs the method of any of claims 10 to 18.

21 . An apparatus for particle production, the apparatus comprising:

a membrane defining a plurality of apertures and configured to receive a first liquid phase and to receive a second liquid phase via the plurality of apertures to form an emulsion;

a first reactor configured to receive the emulsion from the membrane and to at least partially solidify droplets of the second liquid phase in the emulsion; and

an actuator for oscillating liquid flow in the membrane and the first reactor.

22. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.