EP4747000A1

EP4747000A1 - Rotating spiral reactor

Info

Publication number: EP4747000A1
Application number: EP24777033.2A
Authority: EP
Inventors: Jordan Macleod Macinnes; Esther Purna Nithila JOHN KARUNAKARAN
Original assignee: University of Sheffield
Current assignee: University of Sheffield
Priority date: 2023-09-11
Filing date: 2024-09-11
Publication date: 2026-05-27
Also published as: AU2024342409A1; WO2025056900A1; GB202313778D0; CN121816227A; KR20260068771A

Abstract

A rotatable reactor comprising at least one reactor bed that comprises a spiral channel, wherein the spiral channel extends from an inner end to an outer end, and wherein the reactor comprises at least one receiver unit comprising an annular reservoir, wherein the receiver unit rotates with the or each reactor bed, and wherein the annular reservoir of the receiver unit is configured to receive a liquid from a non-rotating source and transfer the liquid to the spiral channel.

Description

ROTATING SPIRAL REACTOR

Field of the Invention

The present invention relates to a reactor that includes a spiral-shaped channel and that can be rotated. The reactor may generally be used for (bio)chemical reactions.

Background of the Invention

Reactors used in common industrial chemical processes can be operated in batch or continuous mode. Stirred tanks can be used in each of these modes. While batch reactors are well known and thought of as reliable, batch reactors typically require additional resource compared to continuous reactors associated with unloading, cleaning and recharging the reactor. Further, as reagents are consumed and products are generated, the reaction conditions in a batch reactor are never optimal throughout a reaction.

In continuously-operated stirred tank reactors (CSTRs), reagents are continuously fed into a stirred tank, and the product is continuously removed from the reactor. CSTRs are useful within industrial chemistry as they are able to mitigate the problems associated with batch reactors. CSTRs may operate at optimum conditions of concentration and temperature, provided that the stirring is sufficiently effective to approximate uniform conditions within the reactor, i.e. characteristic mixing time can be made small in comparison to reaction time.

A key problem associated with CSTRs lies in the replenishment of the reagent and the removal of the product whilst in continuous production. Where the rate of reaction is high, so it is possible to add reagents and remove products quickly, the effect of incomplete mixing is magnified due to the low residence time in the reactor.

Flow reactors have been researched and used extensively over the past 20 years or so. Whereas CSTRs approximate uniform concentration throughout the reactor, flow reactors operate in a plug flow model and concentrations of reagents and products vary along an elongate reactor channel (conduit).

Rotating spiral channel reactors are known but not commonly used. Rotating spiral channel reactors have been found to be particularly suitable for multi -phase reactions. For instance, rotating spiral channels have been used to perform reactions in immiscible liquid-liquid or gas-liquid phase systems (Maclnnes, et al., Chem. Eng. J. (2010), 159 (1-3), 159-169; Chemical Engineering Science, 69 (2012), 304-315).

The rotation in the spiral channel forces the different phases to flow side by side, in parallel flows. Such parallel flows may be co-current or counter-current, with countercurrent flows required for complete transfer of a solute species between immiscible phases, especially during distillation, extraction and absorption.

It is known that controlling the spiral parameters, rotation rate and pressure gradient along the channel can be used to control the flow of the phases and the relative thickness of the phase flows. This allows adjustment to reach the optimum mass transfer and adaption to phase and solute systems having widely differing fluid viscosities, densities, solute diffusivities and interface equilibria.

It will be understood that rotating spiral reactors can more broadly be termed “rotatable spiral reactors” to cover when they are not in motion. It will be understood that this may indicate that they are suitable for stable rotation at high speeds, for example by being balanced.

Rotatable spiral reactors have used sealed connections to transfer reagents from the stationary input streams to the rotating spiral channel(s), and from the rotating spiral channel(s) to the stationary output streams. Figure 1 of the accompanying drawings shows a cross-section through an input unit 10 that includes stationary input/output streams 12, seals 14, rotating central shaft 16. Figure 2 of the accompanying drawings shows an exploded view of spiral reactor bed 20 that would be positioned on top of the input unit 10 shown by Figure 1. Figure 2 shows aluminium clamps 22, 1 mm gaskets 24 (upper gasket made of oil-resistant paper, lower gasket made of PTFE), tempered glass cover 26, spiral channel reactor bed 28, and rotating shaft head 29.

The apparatus shown in Figures 1 and 2 uses lip seals to transfer two fluid phases to and from the rotating spiral unit and to convey cooling water along the seal shaft. The cooling water removes some of the heat generated by bearings and seals to control the operating temperature of the spiral channel. Samples for concentration measurements may be collected at the fluid phase outlets. Photography during rotation can be made possible, for example, if the open face of the spiral channel is covered with an optical glass disk and a magnet in the side of the spiral element triggers to synchronise the camera and a strobe light using a Hall-effect sensor.

However, the use of such sealed connections to transfer reagents and products between rotating and stationary parts of the overall reactor system reduces the commercial efficiency of rotating spiral reactors.

For instance, each seal is exposed to the reagent/product stream, and is subjected to high forces and relative motion, causing degradation through corrosion and/or abrasion, for example, and require replacement on a regular basis. The seals used for this application, which are formed of carbon fibre-PTFE, are specialist and expensive. The potential for seals to fail during use may lead to the spillage of harmful chemicals, which may cause health and safety concerns for users and may require expensive and time consuming cleaning/decontamination.

The friction caused by each seal also increases the energy consumption of the reactor, and may require additional measures to cool the seal.

Without being confined by theory there are several advantages to using rotating spiral reactors. Two main advantages of the rotating spiral are control and predictability.

In relation to control, rotating spiral reactors can control of the way phases come into physical contact. For example, the thickness of a bed of particles can be controlled independently of fluid flow rates. Therefore, it is possible to control mass transfer rates, and specifically to optimise mass transfer rates over the period of time that the phases are in contact (i.e. during a reaction).

Rotating spiral reactors can handle high particle volume fractions. This is achieved by not allowing the particles to distribute into the fluids or forcing the supply fluids through the region occupied by the particles. Instead, the particles are arranged in a bed, i.e. a layer, along one side of a channel, and fluids flow adjacent to but not through this bed. Mass transfer between streams of fluid and the bed is by diffusion. The thickness of the layer can be controlled in order to control the rate of mass transfer. The thickness of the layer can be dependent upon factors such as the reaction rate and diffusion rate. Solid layer thicknesses of several millimetres have been found to be suitable. Depending on flow width required to supply the bed, particle volume fractions of up to 20% have been achieved and particle volume fractions of up to 40% are thought to be achievable.

In relation to predictability, due to the relatively simple configuration of the phases within the spiral reactor, the phase behaviour is more predictable. This increased predictability allows users to reliably design new devices and to facilitate systematic optimisation of devices in relation to a particular reaction system (e.g. the particle type and/or the reaction to be performed).

An advantage of the spiral reactor over conventional CSTRs associated with improved control and predictability includes enhanced productivity. This may be achieved through the precise control of mass transfer conditions, inherent control of reactor temperature uniformity and simultaneous removal of product species. Simultaneous removal of product species may also allow easier and faster product removal, and may limit any negative influence of the product on the system, for instance if the presence of the product influences an equilibrium to generate the product, or otherwise inhibits the reaction (e.g. by denaturing an enzyme and/or poisoning an organism used to perform the reaction).

CSTRs, by contrast, encounter problems as particle volume fraction is increased. In the literature, and likely industrial practice, volume fraction remains below 10%. The particles are in suspension for mass transfer purposes and as 10% volume fraction is approached the typical space between particles is less than one particle diameter, which increases the apparent viscosity of the suspension. Thus, as particle volume fraction increases, there is a related increase in the effective viscosity of the reaction mixture. Consequently, the ability to introduce further reagent supply decreases, and the rate of mass transfer decreases.

So, rotating spiral reactors can achieve higher particle volume fraction than with CSTRs and more effective mass transfer of reagents, nutrients, products and waste material. Improvements of an order of magnitude have been attained using a rotating spiral channel reactor, compared to a CSTR. To these advantages may also be added those indicated in relation to reaction without particles: the controlled handling of additional fluid phases simultaneously, i.e. gas handling and liquid extraction.

Yet another advantage of spiral reactors is that there is less disruption of the heavy (i.e. more dense, e.g. solid) phase. For instance, in reactions where a lighter phase (e.g. gas is evolved in the reaction) must be separated from other phases, the reactor design permits the flow of the lighter phase along the inner wall of the spiral channel. This does not significantly disturb the heavier phase on the opposite (outer) wall of the spiral channel. In CSTRs, the disruption would be significant. Thus, segregation of the phases becomes possible. This is vital as gas generation would normally increase the disruption of the heavy (e.g. solid) phase. This provides particular benefits where the phases are used for extraction and/or where the phases are to be separated.

It can be noted that it is possible to place particles in a bed along a non-rotating channel. However, the rotation introduces 100s of times greater body force on the particles, thus allowing higher flow velocities to be achieved before bed erosion occurs. Hence, a smaller flow section is needed for the liquid so that particle fraction in the reactor is far higher than for a static channel. Extraction flow is also lost for a static channel.

The present invention has been devised with the foregoing in mind.

Summary of the Invention

According to a first aspect, the present invention provides a rotatable reactor. The reactor comprises at least one reactor bed that comprises a spiral channel. The spiral channel extends from an inner end (closest to the axis of intended rotation) to an outer end (furthest from the axis). The reactor also comprises: at least one receiver unit comprising an annular reservoir, wherein the receiver unit rotates with the or each reactor bed, and wherein (the annular reservoir of) the receiver unit is configured to receive a liquid from a non-rotating source and transfer the liquid to the spiral channel; and/or at least one output unit comprising an open ended conduit, wherein the conduit rotates with the or each reactor bed, and wherein the conduit is configured to form a jet of the liquid from the spiral channel such that, in use, the jet can be collected by a nonrotating annular collector. By using one or more receiver unit(s) and/or output unit(s) to introduce and/or offload one or more liquids to/from the rotatable spiral reactor, the spiral reactor is simpler to use (and thus the benefits of spiral reactors can be more easily attained), requires less maintenance, and has lower energy requirements compared to conventional rotatable spiral reactors.

The rotatable spiral reactor of the invention can be used in combination with one or more inputs and/or outputs that require a sealed connection to a static (non-rotatable) unit, for example as shown in Figure 1. However, the use of at least one receiver unit and/or output unit in the place of a sealed input/output connection provides significant benefits. These benefits increase as the number of sealed input/output connections are decreased to zero, as they are replaced by the receiver unit(s) and/or output unit(s) required by the claimed invention. Thus, preferably the reactor has at least one receiver unit and at least one output unit.

Preferably the reactor comprises a means for controlling the pressure of the liquid in the spiral channel (e.g. the pressure at the outer end of the spiral channel). Such a means is not required in rotating spiral channel reactors of the prior art, which have seal units as shown by Figure 1. In rotating spiral channel reactors of the prior art external pressures must be adjusted to control the pressure of the liquid within the spiral channel. However, in the present invention, the levels of liquid in the reservoir(s) can self-adjust by using a means for controlling the pressure of the liquid. The means for controlling the pressure of the liquid in the spiral channel is particularly useful for a liquid flow that proceeds to an output unit comprising an open ended conduit, to prevent the liquid passing straight through the reactor.

The means for controlling the pressure of the liquid is preferably a “weir” that is fluidly connected to an end of the spiral channel, and wherein the crest of the weir is positioned closer to the (in use) axis of rotation and/or the centre of the spiral (defined by the spiral channel) than the end of the spiral channel to which the weir is connected. If the rector does not include an output unit, it would be possible for the weir to be a simple outlet; there is a crest positioned closer to the radial centre of the reactor over which the fluid must flow to escape the reactor. Preferably the means (e.g. weir) is fluidly connected to the outer end of the spiral channel. The reactor may comprise a first means (e.g. weir) connected to the inner end of the spiral channel and a second means (e.g. weir) connected to the outer end of the spiral channel. Preferably the crest of the weir is positioned closer to the (in use) axis of rotation and/or the centre of the spiral than the inner end of the spiral channel. Preferably the means/weir is fluidly connected to the end of the spiral channel using a conduit. The conduit is arranged to direct liquid flowing out of the outer end of the spiral channel to the means/weir, i.e. direct liquid flowing out of the outer end towards the (in use) axis of rotation and/or the centre of the spiral. It will be understood that the liquid flow rate is proportional to the flow rate of liquid into the receiver unit, which may be controlled by an external pump and/or pressure regulator of a delivery unit. In the case of gas flow, an external pressure source is required to produce a difference relative to the case pressure or other reference pressure.

The or each weir can establish a fixed hydrodynamic datum (of combined pressure, gravity and centrifugal energy) with a radial level of the liquid or gas in the receiver unit. A weir can force the reservoir level to exceed the datum by an amount proportional to the frictional losses in the spiral flow. The flow rate of the liquids is determined by the rate that liquid is fed to the receiver unit. The radial position (i.e. the distance from the axis of rotation) of the weir and the incoming liquid flow rate determines the liquid level in the annular receiver that develops to drive the imposed flow. Where there are multiple liquid phases and phases it will be appreciated that the radial positions of the weirs and the incoming liquid flow rates determine the liquid levels in the annular receivers that develop to drive the imposed flows.

The skilled person will understand that, where liquid-liquid flow is used, the radial positions of the weirs must be configured such that the separate phases flow separately out of the reactor, i.e. the heavy liquid phase does not pass out the light phase outlet and the light phase does not pass out the dense phase outlet.

The benefits relating to introducing and/or offloading liquids to/from the rotatable spiral reactor allows the user to more readily attain the benefits associated with rotatable spiral reactors, such as controllability. Spiral reactors encourage the phases to remain in distinct, continuous, phases and can therefore avoid the formation of ‘slugs’, and/or the foaming and/or emulsification of separate phases. Flow and interface shape is simple and predictable. Spiral reactors can be used to perform in-situ product removal, which demonstrates increased efficiency when compared to traditional reactors.

The Examples show that reactors of the invention can be used for prolonged periods of time, such as 4 days or longer.

The ordering of phases in a spiral reactor is generally determined by the relative density of the phases, with more dense phases being forced to the outside of the spiral channel and less dense phases being forced to the inside of the spiral channel.

Gasses are lower in density compared to liquid and/or solid phases. In multiphase reactions that involve a gas phase, the gas is forced to the inner boundary of the spiral, which can drive equilibria towards further generation of gas in gas-producing reactions.

Solids tend to be higher in density compared to liquid and/or gas phases. It has been determined that spiral reactors are particularly useful for performing multiphase (i.e. involving two or more phases) flow reactions that involve a solid phase (e.g. cells). The spiral channel can provide a layer of the solid phase that is controllable and uniform in thickness, and that is substantially stationary.

The Examples show that reactors of the invention can maintain a bed of solid particles (e.g. cells), and can readily handle gas (e.g. produced by a reaction in the spiral channels).

The Examples show that the rate of rotation can be used to control the thickness of a bed of particles in the spiral channel. Higher rates of rotation may attenuate drifts of the bed.

This allows reagents in other phases, flowing past the solid phase, to be able to contact the solid phase continuously and consistently, providing excellent efficiency for reactions requiring interaction between the phases. It will be appreciated that mass transfer between phases is by diffusion, although assisted in the fluid flows by transverse motions due to curvature and rotation effects. The layer thicknesses can be controlled to ensure suitable mass transfer rates for a given reaction. It will be appreciated that, for a given mass, mass transfer rates will be higher where the layer is thinner. Indeed, rotating spiral reactors can handle high particle volume fractions in the form of (substantially) immobile particle beds on the sidewall of the spiral channels.

According to a second aspect the claimed invention provides a method of depositing a layer of particles within a spiral channel. The method comprises: providing a spiral channel; charging a suspension of the particles into the spiral channel; and rotating the spiral channel while the suspension is within the spiral channel. It will be understood that a layer of particles is deposited within the spiral channel and a supernatant remains in the spiral channel. The method may comprise removing the supernatant (i.e. the liquid resulting after the deposition of the particles).

Preferably the spiral channel is of a reactor of the first aspect and the method comprises: providing a spiral channel; whilst the spiral channel is rotating, charging a suspension of the particles into the spiral channel; and allowing the rotation of the spiral channel to continue for a period of time. Optionally, the spiral channel is of a reactor that comprises a seal unit to deliver one or more liquid phase, and the suspension is charged into the spiral channel before the rotation of the spiral channel is initiated.

The method may use a reactor of the first aspect that includes a receiver unit, and the method may comprise providing the suspension of the particles to the receiver unit. Preferably the receiver unit is fluidly connected to the inner end of the spiral channel. The end of the spiral channel distal to the receiver unit may be plugged (i.e. closed) while the suspension is charged into the spiral channel.

The particles may be a reagent or catalyst for performing a chemical reaction. For example, the particles may comprise, or be, biomass such as enzymes, cells or agglomerations of cells.

It has been determined that by filling the spiral channel with a suspension while the spiral channel is rotating, the spiral channel is filled efficiently and effectively, in a highly uniform manner, and with minimal gurgling of air back through the spiral channel (which would reduce the uniformity of the deposition of the particles). The rotation of the spiral channel provides a centrifugal force that acts upon the particles and deposits the particles in a uniform layer on the outer wall of the spiral channel. The rate at which the suspension is injected may be controlled to adjust the depth of the flow of the suspension along the outer wall, and hence the depth of the outward flow of the gas in the channel (or the ratio of these depths to one another within the spiral channel). The rotation rate (during injection) may additionally or alternatively be controlled to adjust the depth of the flow of the suspension and/or the depth of any gas pockets where gurgling is present.

Streamwise vortices are produced by the spiral channel curvature and Coriolis acceleration that can serve to stir the suspension as it flows into place, maintaining the suspension and preventing particle settling (onto the outer wall). Once (all or a portion of) the channel has been filled with the suspension, the effects caused by the Coriolis acceleration and the curvature cease, and the particles settle to the outer wall of the channel.

CN 106495192B describes a process for preparing hydrotalcite having a uniform particle size distribution by hydrothermal crystallization using an ultra-gravity rotary bed reactor. A liquid distributor is positioned in the radial centre of a drum with radially interleaved, rather than vertically stacked, spiral passages. The liquid distributor sprays fluid directly into spiral passages in a drum. A seal would be required to transfer the other liquid into the drum. The output fluid sprays out of the spiral channels, in an uncontrolled manner, into the air surrounding the reactor. No significant fluid pressure would build up within this reactor because there is no means to control the pressure of liquid in the spiral channels.

US5556765A describes a bioreactor that can mix reactants with organisms. The bioreactor includes a rotatable tubular “spiroid” tube, whereby rotation of the bioreactor causes rotation of the spiroid and transport of liquid and gas phases through the spiroid lumen under the gravity effect on the denser liquid slugs. The “spiroid” lumen need not be a spiral. The spiroid is a curved tube fixed in a horizontal rotating cylindrical vessel that is arranged to dip into and out of a liquid bath to alternately trap slugs of gas and liquid. Therefore, this device needs to be arranged to rotate slowly, not providing significant centrifugal acceleration as in the present invention, and so there is no significant fluid pressure within the spiroid tube. High rates of rotation would prevent this device from working as intended. CN1461731A describes a method for preparing nano-scale ultrafine calcium carbonate by using a rotating bed with interleaved, rather than stacked, spiral channels. While this disclosure is ambiguous, it appears that a liquid is sprayed straight into the spiral channels. The output fluid would spray out of the spiral channels, in an uncontrolled manner, into the air surrounding the reactor. No significant fluid pressure would build up within this reactor because there is no means to control the pressure of liquid in the spiral channels.

CN213348911U describes a high-efficiency heat exchange continuous flow reactor. This device uses seals to transfer fluids from non-rotating parts to rotating parts. Multiple stacked spiral channels are used. Conduits connecting the inner ends of the spiral channels are described, but these are used only to guide a coolant fluid flow rather than to balance the pressure of a reaction mixture across multiple reactor beds. Furthermore, there is no consideration of ensuring equal fluid flow to each of the spiral channels in a vertically arranged stack (i.e. where the spiral channels extend across a horizontal plane) as in the present invention. Further, the output fluid sprays out of the spiral channels, in an uncontrolled manner, into the gas surrounding the reactor.

However, none of these documents disclose a receiver unit comprising an annular reservoir, as required by the claimed invention. In some cases the fluid passes straight into the spiral channels. Seals are commonly used in these documents to transfer liquids into the spiral channels. There is no disclosure of an annular receiver having a continuous annular sidewall.

Furthermore, none of these documents disclose a means for controlling the pressure of liquid in the spiral channel, such as a weir, because the fluid presented to the inner end of the spiral channels passes through the spiral channels without building up a pressure.

There is no disclosure of a plurality of receiver and/or output units, and there is no disclosure of gas handling capabilities.

Furthermore, there is no disclosure of a solid phase being deposited within the spiral channels disclosed in these documents.

At least CN106495192B and CN1461731A describe wide fluid output channels that would result, under high centrifugal acceleration, in atomisation of the liquid into a very fine mist rather than providing a fluid jet. Furthermore, these documents would not be able to form or retain a solid particle (e.g. cell) bed as the fluid would flow out of the channels at a high rate.

In addition, these documents do not describe an output unit that forms a jet from the liquid of a spiral channel and that has an annular collector with a radius that is equal to or smaller than the radius of the spiral channel.

Apparatuses of the prior art, including CN106495192B and CN1461731A, require liquids to be sprayed into drums, thereby typically requiring pumps to be used. However, the receiver unit of the present invention is able to feed fluids into the annular receiver under gravity and therefore can avoid the requirement for pumps.

The disclosure of the present application includes the subject-matter of the following clauses:

1.A rotatable reactor comprising at least one reactor bed that comprises a spiral channel, wherein the spiral channel extends from an inner end to an outer end, and wherein the reactor comprises: at least one receiver unit comprising an annular reservoir, wherein the receiver unit rotates with the or each reactor bed, and wherein the receiver unit is configured to receive a liquid from a non-rotating source and transfer the liquid to the spiral channel; and/or at least one output unit comprising an open ended conduit, wherein the conduit rotates with the or each reactor bed, and wherein the conduit is configured to form a jet of the liquid from the spiral channel such that, in use, the jet can be collected by a non-rotating annular collector.

2. The rotatable reactor of clause 1, wherein the reactor further comprises a means for controlling the pressure of liquid in the spiral channel.

3. The rotatable reactor of clause 2, wherein the means for controlling the pressure of the liquid in the spiral channel is a weir fluidly connected to an end of the spiral channel, wherein the crest of the weir is positioned closer to an axis of intended rotation and/or the centre of the spiral defined by the spiral channel than the end of the spiral channel to which the weir is connected.

4. The rotatable reactor of clause 2 or clause 3, wherein the reactor comprises more than one spiral channel.

5. The rotatable reactor of clause 4, wherein each spiral channel has a corresponding means for controlling the pressure of liquid within the spiral channels. 6. The rotatable reactor of clause 4 or clause 5, wherein the rotatable reactor further comprises a conduit connecting the inner ends of the spiral channels and/or a conduit connecting the outer ends of the spiral channels.

7. The rotatable reactor of any preceding clause, wherein the reactor comprises: a) one receiver unit and one output unit, or b) two receiver units and two output units.

8. The rotatable reactor of any preceding clause, wherein the annular reservoir comprises an annular sidewall.

9. The rotatable reactor of any preceding clause, wherein the or each receiver unit, spiral channel, reactor bed and output unit are coaxial with one another.

10. The rotatable reactor of any preceding clause, wherein the reactor comprises a delivery unit configured to provide liquid to the receiver unit.

11. The rotatable reactor of any preceding clause, wherein the reactor comprises an annular collector.

12. The rotatable reactor of any preceding clause, wherein the reactor is configured to withstand accelerations of 50g or more.

13. The rotatable reactor of any preceding clause, wherein the reactor comprises a gas input conduit and/or a gas output conduit.

14. The rotatable reactor of clause 13, wherein the gas input conduit and/or the gas output conduit is coaxial with the axis of intended rotation.

15. The rotatable reactor of clause 13 or clause 14, wherein the gas input conduit is fluidly connected with the outer end of the or each spiral channel, and/or the gas output conduit is fluidly connected with the inner end of the or each spiral channel.

16. A method of depositing a layer of particles within a spiral channel, wherein the method comprises the steps of: providing a spiral channel; charging a suspension of the particles into the spiral channel; and rotating the spiral channel while the suspension is within the spiral channel.

17. The method of clause 16, wherein the method comprises: providing a spiral channel; whilst the spiral channel is rotating, charging a suspension of the particles into the spiral channel; and allowing the rotation of the spiral channel to continue for a period of time.

18. The method of clause 16 or clause 17, wherein spiral channel is the spiral channel of a reactor as defined by any one of clauses 1-15.

19. The method of any one of clauses 16 to 18, wherein the method further comprises removing the supernatant. Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view through the input and output section of a comparative reactor;

Figure 2 is an exploded view of the reactor bed of a comparative reactor configured to sit on the apparatus shown in Figure 1 ;

Figure 3 is a perspective view of a reactor according to the invention, shown without the side in place to reveal the reactor bed;

Figure 4A and Figure 4B are photographs of a reactor according to the invention;

Figure 5 is a cross-sectional view through a reactor according to the invention with lines indicating the liquid flow path;

Figure 6 is a is a cross-sectional view through a reactor according to the invention that has six spiral channel reactor beds and that is configured to allow a second liquid to flow counter-currently (e.g. for product extraction);

Figures 7A-C show cross-sectional views through a reactor similar to that shown by Figure 6;

Figure 8 is a photograph of a reactor according to the invention shown in Figures 7A-C, configured for extraction flow with six spiral channels;

Figures 9A-F show schematic cross-sectional views through a reactor according to the invention illustrating various flow networks;

Figure 10 shows a schematic cross-sectional view through a reactor according to the invention illustrating a flow network with three reactor beds;

Figures 11A-B shows plan views of a spiral channel of a reactor shown in Figures 1 and 2 during use, where Figure 1 lb shows an enlarged view of a section of Figure 1 la;

Figure 12 is a graph comparing the rate of production of 2-phenylethanol using a reactor of the invention shown in Figures 3-5, with comparative results using against CSTRs (comparative);

Figure 13 shows a plan view of a bed of watermelon seed powder with DI water flow in a spiral channel of a reactor of the invention shown in Figures 3-5; Figure 14 shows a graph of bed thickness against particle load in an initial suspension of watermelon seed powder, using a reactor of the invention shown in Figures 3-5;

Figures 15A-B show plan views of: A) growth of an initial bed of Kluyveromyces marxianus cells, B) growth of a bed of Kluyveromyces marxianus cells at the end of an 8-hour production run in a spiral channel of a reactor of the invention shown in Figures 3-5;

Figure 16 shows a plan view of oxygen gas being produced by a bed of watermelon seed powder in a spiral channel of a reactor of the invention shown in Figures 3-5;

Figures 17A-B show plan views of a bed of Kluyveromices marxianus cells with media flow and counter-current flow of decane, in A) the thin media mode and B) the thick media mode, in a spiral channel of a comparative reactor shown in Figures 1-2;

Figure 18 shows a plan view of the operation of the six-spiral channel reactor as shown in Figures 6 and 7, using butanol as the extract liquid;

Figure 19 is a graph showing the butanol-water interface position in the adjustment reservoir over a range of rotation rates for equal liquid phase flow rates of 0.19mL/min/channel in the six-spiral channel reactor shown in Figures 6 and 7; and

Figure 20 shows the variation in bed thickness (log scale) over 60 hours during two runs at different rotation rates: 2000rpm and 2400rpm.

Detailed Description of the Invention

The invention provides a rotatable reactor as defined by the first aspect.

The reactor may be used for performing a reaction, or for another operation such as extracting a material from one phase into another. Thus, the reactor does not have to be used to perform a chemical reaction.

The reactor may comprise at least one receiver unit and at least one output unit, for example one or two receiver units and one or two output units. Preferably the reactor has two receiver units and two output units. Two or more receiver and/or output units are particularly beneficial where the reactor is for contacting two immiscible liquids in a counter-flow or co-flow arrangement. Two or more receiver units and one output unit may be used where two different liquids are to be charged to the reactor.

It will be appreciated that the reactor may comprise one or more reactor beds, one of more spiral channels, one or more receiver units, and one or more output units. While the disclosure may be explicitly made in relation to one of each of these components, the disclosure is intended to also relate to more than one, for example all, of each of these components unless otherwise incompatible. It will be appreciated that the number of spiral channels and/or reactor beds can be increased in order to increase the throughput of the reactor. It will be appreciated that the number of receiver units and output units may correspond to the number of liquid phases that the reactor is configured to handle when in use.

A rotatable body may comprise the components of the reactor that are intended to rotate, such as the or each receiver unit and/or output unit, the or each reactor bed, the or each spiral channel, and optional components such as the means to control the liquid pressure. The rotatable body may be rotationally coupled to a fixed frame, for example by means of bearings.

The rotatable body may comprise a shaft, such as an elongate shaft. The axis of (intended) rotation may be centred on the axis of the shaft. Components of the reactor may be coaxial with one another, i.e. configured for rotation about substantially the same axis. For example, the (or each) receiver unit, spiral channel, reactor bed and output unit may be coaxial with one another and/or the shaft.

The skilled person will appreciate that the acceleration on the reactor, and the fluids therein, will be dependent upon the radius of the device and the rate of rotation. The rotatable body and/or rotatable components of the reactor, may be configured to withstand accelerations of 50g or more, or 100g or more, such as 400g or more, or 500g or more, such as 1000g or more (e.g. 100,000g or less, such as 10,000g or less, or from 50g to 100,000g). The rotatable body and/or rotatable components of the reactor, may be configured to withstand rotation at speeds of 200RPM or more, such as 300RPM or more, such as 400RPM or more, such as 2000RPM or more (e.g. 100,000RPM or less, such as 20,000RPM or less, or from 200RPM to 100,000RPM). It will be appreciated that staged reactions may be achieved by connecting two or more reactors and/or feeding the output from one reactor into another reactor.

Receiver unit

The reactor may comprise at least one receiver unit. The or each receiver unit comprises an annular reservoir. The or each receiver unit rotates with (i.e. in unison with) the (or each) reactor bed. Thus, in use, the receiver unit can rotate in unison with the or each spiral channel/reactor bed. The receiver unit is configured to receive a liquid from a non-rotating source. The receiver unit is configured to transfer the liquid to (i.e. into one end of) the spiral channel. The liquid may then flow through the spiral channel.

The annular reservoir may include an annular sidewall. The annular sidewall is preferably substantially centred on the axis of (intended) rotation. The annular sidewall preferably extends along and around (i.e. all of the way around) the axis of (intended) rotation. The annular sidewall should be substantially continuous.

The annular reservoir may have a base (e.g. platen). The base is preferably generally perpendicular to the axis of (intended) rotation. The reservoir can be fed by a flow of liquid from the base.

The receiver unit may be substantially U-shaped in cross-section where it includes a base and the annular side wall. The receiver unit should be configured to prevent the liquid from escaping before it enters the spiral channel.

A delivery unit, configured to provide liquid to the receiver unit, may (or may not) be part of the reactor. The delivery unit may comprise a means to control the flow rate of the liquid (e.g. a syringe pump) and/or a conduit arranged to provide the liquid to the receiver unit.

Liquid that enters the receiver unit (e.g. through a conduit or stream) usually first contacts the base of the receiver unit. Preferably the base is circular. Preferably the receiver unit (e.g. the annular reservoir) is substantially rotationally symmetrical about the (intended) axis of rotation. Upon contact with the receiver unit, the liquid is accelerated, due to the rotation, towards the annular sidewall of the annular reservoir. The degree to which the liquid is accelerated towards the annular sidewall is dependent upon the rate of rotation of the receiver unit and/or the liquid flow rate. The skilled person will understand that, where the liquid initially contacts the base (platen), it is possible to calculate the depth of the layer of liquid on the base as a function of radial position, and the mean residence time on the base before reaching the liquid on the sidewall. The transfer of heat and/or mass (of gaseous species) may occur during the time that the liquid is in contact with the receiver unit. The rate of such transfer may depend upon flow rate, rotation rate and platen arrangement. This can allow the fed liquid to be saturated with a gas species by controlling the gas composition over the platen and can ensure that the liquid entering the spiral channel is at the reactor temperature.

The annular reservoir can prevent the liquid from escaping the receiver unit as it is accelerated laterally by the rotation. Each side of the annular reservoir may be substantially J-shaped or C-shaped or l-shaped or L-shaped in cross-section. Preferably each side of the annular reservoir has a substantially J-shaped cross-section. Preferably the sidewall is unitary with the base.

The annular reservoir may comprise a top (e.g. lid) to assist with preventing liquid from leaving the annular reservoir once it has entered the annular reservoir and/or to prevent contaminants from entering the annular reservoir. The top may have an orifice (e.g. an annular orifice) to allow the entry of the liquid as the annular reservoir rotates. Preferably the top is unitary with the sidewall of the annular reservoir.

The skilled person will understand that the inner radius of the annular reservoir rim should be small enough that the receiver does not overflow during any stage or under any normal condition of operation. The higher the flow rate, the further in radially must the rim be placed in the design. Gas handling may require increased receiver capacity due to the potential for gases to exit the reactor through the receiver unit. Further, if pulsating pumping (characteristic of positive displacement pumps) is used to introduce the liquid to the receiver unit, reservoir capacity should be increased to attenuate variations in the flow rate to the spiral channel. The receiver unit is configured to receive a liquid from a non-rotating source. Thus, the receiver unit may have an annular opening to allow the liquid to be introduced from a non-rotating source. This may allow a static conduit to charge the liquid into the receiver unit. Preferably the annular opening is centred on the axis of rotation and extends around the axis of rotation, in a plane perpendicular to the axis of rotation.

The receiver unit is configured to transfer the liquid to the spiral channel. The receiver unit has one or more outlets (e.g. conduits) that fluidly connects the internal surface of the reservoir to one end of the or each spiral channel. This allows the liquid received by the receiver unit to be passed to the spiral channel. Preferably the outlet of the receiver unit is located on the base (e.g. at the outer edge of the base) and/or on the annular sidewall (e.g. at the edge of the annular sidewall that contacts the base). The reservoir may have a separate outlet for each spiral channel; for example, a receiver unit for a 10-spiral channel stack could have 10 outlet connection passages that are equally spaced around the annular reservoir. Individual connecting passages from a common reservoir is believed to allow for the best use of space and accommodation of necessary structural elements.

The receiver unit is configured to receive a liquid and is configured to transfer the liquid to spiral channel. The receiver unit may be configured to transfer the liquid to the inner end or the outer end of the spiral channel. Preferably at least one receiver unit of the reactor is configured to transfer liquid to the inner end of the spiral channel. Preferably the reactor has two or more receiver units where a first receiver unit is configured to transfer liquid to the inner end of the spiral channel and where a second receiver unit is configured to transfer liquid to the outer end of the spiral channel.

Reactor bed

The reactor comprises at least one reactor bed that comprises a spiral channel. The reactor bed is, in effect, a body defining one or more spiral channels, for example a conduit. It will be appreciated that more than one spiral channels are normally arranged in different planes to one another. The spiral channels do not normally intersect one another, in other words they are normally independent from one another. The reactor may comprise a plurality of reactor beds that are stacked. The reactor comprises one or more, such as two or more, or four or more, reactor beds. The reactor may comprise 200 or fewer, such as 100 or fewer, or 50 or fewer reactor beds, such as 40 or fewer reactor beds, such as 20 or fewer reactor beds. The reactor may comprise from one to 50 reactor beds, such as from two to 40 reactor beds, or from two to 20 reactor beds. The or each reactor bed comprises one or more spiral channels, such as two or more, or four or more spiral channels. The or each reactor bed may comprise 50 or fewer spiral channels, such as 40 or fewer spiral channels, such as 20 or fewer spiral channels. The reactor may comprise from one to 50 spiral channels, such as from two to 40 spiral channels, or from two to 20 spiral channels.

Each reactor bed may have one fluid connection for the inner end of each spiral channel in the reactor bed. Each reactor bed may have one fluid connection for the inner ends of some or all of the spiral channels that it contains. Each reactor bed may have one fluid connection for the outer end of each spiral channel in the reactor bed. Each reactor bed may have one fluid connection for the outer ends of some or all of the spiral channels that it contains.

Where the reactor comprises more than one spiral channel the reactor may comprise a conduit connecting either the inner ends or the outer ends of the spiral channels. This conduit can ensure equal distribution of the feed liquids to each of the spiral channels. There may be one such conduit connecting the inner ends, and another such conduit connecting the outer ends. Such a conduit may be referred to as a column. In use, such a conduit may contain a static column of liquid. A conduit connecting the inner ends of the spiral channels is for the less dense phase in use. A conduit connecting the outer ends of the spiral channels is for the more dense phase.

The reactor bed may be a substantially cylindrical body. The reactor bed may include conduits to (fluidly) connect the or each spiral channel to the receiver unit, the or each conduit connecting either the inner ends or the outer ends of the spiral channel, the output unit and/or the weirs.

Each spiral channel may be enclosed (across the cross-section of the spiral channel) to prevent fluid from leaving the spiral channel, especially under rotation. The reactor may comprise a lid for the or each reactor bed, to enclose the or each spiral channel. One reactor bed may act as a lid for (the spiral channel of) a second reactor bed. The lid for the spiral channels may comprise apertures and/or conduits configured to pass input and/or output streams.

Spiral channel

The rotatable reactor provides particular advantages when used with multi-phase systems, for example where phases are contacted within the spiral channel while it is rotated. The rotating spiral channel may allow a solid phase (e.g. cells, such as a biofilm) to be stabilised by centrifugal acceleration. The solid phase may be continuously supplied, for example with reagents, through a sustaining media in a liquid phase that flows over the solid phase.

The reactor may comprise one spiral channel or more than one spiral channels. Preferably, the rotating spiral reactor comprises a plurality of spiral channels. The reactor may comprise two or more spiral channels, or four or more, or ten or more spiral channels. The reactor may comprise 100 or fewer spiral channels, such as 50 or fewer spiral channels, or 20 or fewer spiral channels. The reactor may comprise from one to 100 spiral channels, such as from 2 to 100 spiral channels, or from 4 to 50 spiral channels.

Where the reactor has two or more spiral channels, preferably the spiral channels are connected in parallel. Preferably the two or more spiral channels have a common connection to one another on one or both ends of each of the channels to provide equal flow to the individual spiral channels. Preferably the same end (i.e. inner and/or outer end) of each spiral channel is connected together as the common connection. Preferably the common connection between the spiral channels is equidistant from centre of and/or the axis of rotation of the spiral channels (at the point where it connects with each of the spiral channels). Preferably the common connection between the spiral channels is equidistant from the axis of rotation of the spiral channels over its path between its connection with each of the spiral channels.

There may be an (individual/separate) means to control the liquid pressure (e.g. weir) between each spiral channel and the common connection. Preferably there is a means to control the liquid pressure between the outer end of each spiral channel and the outer common connection. Once past the means to control the liquid pressure (e.g. weirs), the individual outlet streams are preferably combined to use a common output unit, but they may use individual output units. There may additionally or alternatively be a means to control the liquid pressure (e.g. weir) between the inner end of each spiral channel and the inner common connection, especially where there is a less dense liquid phase flowing counter-currently with a more dense liquid phase.

There may be one means to control the liquid pressure (e.g. weir) for each common connection, fluidly connected between the common connection and an output unit. Thus, more preferably there may be a means to control the liquid pressure (e.g. weir) between (e.g. fluidly connected between) a common connection and the output unit. There may be no means to control the liquid pressure between each spiral channel and the common connection. More preferably there may be a means to control the liquid pressure (e.g. weir) between (e.g. fluidly connected between) the outer common connection and the output unit and there may be a means to control the liquid pressure (e.g. weir) between (e.g. fluidly connected between) the inner common connection and the output unit. There may be no means to control the liquid pressure between each spiral channel and the common connection.

Preferably the two or more spiral channels have a common connection to one another on both ends of the channels, which may be termed an “inner common connection” and an “outer common connection” for the inner and outer ends of the spiral channels respectively. In systems where fluids flow in only one direction through the spiral channel(s), the inner common connection will usually be at the input of the spiral channel and the outer common connection will usually be at the output of the spiral channel. However, it is possible for the inner common connection to be the output of the spiral channels and the outer common connection to be the input of the spiral channels. In systems where fluids flow in two directions (counter-currently) through the spiral channels, the inner common connection and the outer common connection will each perform roles as input and outputs of the spiral channel.

In systems where a single liquid phase flows, the common inlet condition will be the single receiver reservoir free surface hydraulic datum and the common outlet condition will be the individual outlet weirs placed at exactly the same radial position to provide a common hydraulic datum. In the case of two immiscible liquid phases, flowing either co-currently or counter-currently, four different common connections are likely to be involved: the two different reservoir levels and the two sets of outlet weir positions, although the common input of one phase may be shared with the common output of the other phase and vice versa.

The centre of the spiral may be referred to as the origin of the spiral. The or each spiral channel may be centred on (i.e. its origin coaxial with) the axis of (intended) rotation that, in use, the reactor bed is rotated around. Where the reactor has two or more spiral channels, preferably the spiral channels have the same axis of rotation (i.e. are coaxial with one another).

Where there are two or more spiral channels and/or reactor beds, each of the spiral channels and/or reactor beds may be azimuthally (e.g. about the axis of rotation) offset relative to one another (whilst still being coaxial with one another). The offset may be configured to rotationally balance the spiral channels and/or reactor beds. For instance, the spiral channels may be azimuthally offset relative to one another by 360/n degrees (e.g. about the axis of rotation), where n represents the number of spiral channels.

The spiral channel may be substantially flat (e.g. flat), i.e. extending in two dimensions, i.e. extending on a plane. The spiral may extend out of the plane, but preferably the spiral does not extend out of the plane. The spiral may extend to the axis of rotation, but usually the spiral does not extend to the axis of rotation.

The spiral channel may extend over one or more complete turns, such as two or more, preferably four or more, or six or more, such as seven or more, or eight or more complete turns. The spiral channel may extend over 100 or fewer complete turns, such as 80 or fewer, or 60 or fewer, such as 40 or fewer, preferably 20 or fewer, for example 15 or fewer, or 12 or fewer, or 10 or fewer, such as 9 or fewer, or 8 or fewer complete turns. The spiral channel may extend over from one to 100 complete turns, such as from two to 40 complete turns, such as from four to 20 complete turns.

The minimum inside diameter of the spiral, measured as the smallest distance from the centre of one side of the spiral channel to the centre of the other side of the spiral channel through the axis of the spiral (i.e. twice the minimum radius to the inner end of the spiral channel), may be 1cm or more, such as 5cm or more, or 8cm or more, or 10cm or more. The minimum inside diameter of the spiral may be 2m or less, such as Im or less, or 50cm or less, for example 40cm or less, or 30cm or less. The minimum inside diameter of the spiral may be from 1cm to 2m, such as from 5cm to Im, or from 8cm to 40cm.

The maximum outside diameter of the spiral, measured as the largest distance from the centre of one side of the spiral channel to the centre of the other side of the spiral channel through the axis of the spiral (i.e. twice the maximum radius to the outer end of the spiral channel), may be 2cm or more, or 5cm or more, such as 10cm or more, or 20cm or more, or 30cm or more, or 70cm or more, or Im or more, such as 2m or more. The maximum outside diameter of the spiral may be 10m or less, such as 5m or less, or 2m or less, such as Im or less, for example 80cm or less, or 60cm or less, for example 40cm or less. The maximum outside diameter of the spiral may be from 10cm to 10m, for example from 20cm to Im, or from 20cm to 80cm.

The inner end of the spiral channel is closer to the axis of (intended) rotation than the outer end of the spiral channel. Preferably the spiral channel constantly increases in radius from the axis of (intended) rotation from the inner end to the outer end. The increase in radius is preferably consistent along the length of the spiral channel. Preferably the spiral channel has smooth wall surfaces (i.e. not bumpy or rough).

The type of spiral may be selected such that substantially constant centrifugal force acts upon the fluid(s) as it or they pass along the spiral channel. This can be important to ensure constant contacting conditions along the entire length of the channel. These benefits are particularly realised in multi -phase (e.g. multi fluid phase) systems, where consistency of the contacting conditions along the length of the spiral channel can be important. The spiral channel may be in the form of an Archimedean spiral, a hyperbolic spiral, or a Fermat’s spiral. Preferably the spiral is an Archimedean spiral, which provides constant centrifugal force upon the phases along the spiral channel.

The channel may have any suitable depth. The depth of the channel may be determined as the cross-sectional dimension at any position along the length of the channel parallel to the axis of intended rotation and/or perpendicular to the plane of the spiral. The depth of the channel may be 0.01mm or more, preferably 0.05mm or more, or 0.08mm or more, such as 0.1mm or more, such as 0.5mm or more, or 1mm or more, such as 1.3mm or more. The depth may be 50mm or less, or 20mm or less, preferably 10mm or less, or 8mm or less, such as 5mm or less, for example 3mm or less, or 2mm or less. The depth may be from 0.01mm to 50mm, such as from 0.05mm to 10mm, preferably from 0.05mm to 5mm.

The channel may have any suitable width. The width of the channel may be determined as the cross-sectional dimension at any position along the length of the channel perpendicular to the axis of intended rotation (and/or parallel with the plane of the spiral). The width of the channel may be 0.01mm or more, such as 0.05mm or more, preferably 0.1mm or more, or 0.2mm or more, such as 0.5mm or more, or 1mm or more, such as 1.3mm or more. The width may be 50mm or less, or 20mm or less, such as 10mm or less, preferably 5mm or less, for example 3mm or less, or 2mm or less, such as 1.8mm or less, or 1.2mm or less, or 1mm or less. The width may be from 0.01mm to 50mm, such as from 0.05mm to 10mm, preferably from 0.1mm to 5mm.

The cross-sectional shape of the channel, perpendicular to the length of the spiral, may be any suitable shape. Preferably the shape is circular, oval, or rectangular (e.g. square, optionally with rounded or non-rounded corners). The skilled person will understand that, where a solid phase is to be used in the reactor, the thickness of the solid phase at each position is determined by the height of suspension directly above it (in the radial direction). So, for example, a circular section would result in a solid phase that is thickest at the centre of the outer wall, decreasing in thickness away from that centre position. Further, particles settling on the sloping portions of the outer wall would likely slide in towards the centre. Such a situation corresponds to relatively poor utilisation of the channel. Preferably, the channel shape is rectangular, especially where a solid phase is present within the reactor, so that a uniform thickness of the solid phase can be formed.

Controlling the flow rate of fluids

The flow rate of the fluids through the spiral channel may be modified according to the action being undertaken. For example, high flow rates may be preferred during suspension injection and/or cleaning.

The reactor may comprise a means for controlling the flow rate of the liquid through the spiral channel. The skilled person will appreciate that the flow rate through the reactor (during its steady state, where the channels are filled) depends upon the rate of introduction of fluids to the spiral channel. Therefore, controlling the flow rate requires controlling the rate of introduction of fluids to the spiral channel. Increasing the rate of introduction of the fluids to the spiral channel increases the flow rate of that fluid through the spiral channel. The level of liquid within the spiral channel can be controlled by a means to control the pressure within the spiral channel (e.g. weir), establishing a datum that is also present in the reservoir of the receiver unit. Therefore, like a U-bend in traditional plumbing applications, introducing liquid to the receiver unit at a faster rate can increase the flow rate through the spiral channel. For example, the means may comprise an external pump (e.g. for liquids) or pressure regulator (e.g. for gasses) to control the rate of fluid flow into the receiver unit or through the gas passages.

Where there are two immiscible liquid phases for a stack of spiral channels, the provision of either a heavy phase or light phase quasi-static column of liquid can be used to ensure equal distribution of flows from the receiver unit. These are described above as common connections.

Controlling pressure in the spiral channel(s)

The reactor may comprise one or more means for controlling the pressure within the spiral channel, for example a weir. Preferably a means for controlling the pressure within the spiral channel is (fluidly) connected to the outer end of the spiral channel. The reactor may additionally or alternatively comprise a means for controlling the pressure within the spiral channel (fluidly) connected to the inner end of the spiral channel.

The means for controlling the pressure of the liquid may be a conduit with a lower cross- sectional area than the spiral channel, wherein the conduit is fluidly connected to the inner and/or outer end of the spiral channel. The spiral channel may have a cross sectional area that is smaller than the cross sectional area of the conduit(s) connecting the spiral channel to one or both of the receiver and output units.

Preferably the or each means is a weir. The weir is (fluidly) connected to the (inner/outer) end of the spiral channel. The crest of the weir is positioned closer to the (in use) axis of rotation and/or the centre of the spiral (than the outer end of the spiral channel). The weir makes the reactor into something akin to a U-bend in traditional plumbing applications, where when no liquid is being added the level on one side is substantially the same as the level on the other side. In a U-bend, gravity acts upon the liquid. In the reactor, the rotation increases the centrifugal force upon the liquid and the. weir can be used in combination with the rate of rotation to control the pressure within the spiral channel.

The reactor may comprise a conduit arranged to direct liquid flowing out of the spiral channel towards the axis of rotation in use and/or the centre of the spiral. The conduit can (fluidly) connect the outer end of the spiral channel to the weir. Preferably the conduit is substantially parallel with the plane of the spiral channel. Preferably the conduit is substantially parallel with the radius of the axis of (intended) rotation, i.e. perpendicular to the axis of (intended) rotation.

The weirs (i.e. the crests of the weirs) discussed herein generally establish one or more hydrodynamic datums with the reservoir levels feeding the spiral channel(s). The fixed hydrodynamic datum(s) of combined pressure, gravity, and centrifugal energy allow the fluid within the reactor to be subjected to high forces caused by the rotation of the spiral channel(s) in use.

Preferably the or each weir is positioned closer to the (in use) axis of rotation and/or the centre of the spiral than the outer end of the spiral channel. This assists in avoiding stripping off a bed of particles (e.g. cells) from the spiral channel. The or each weir may be positioned at a distance, relative to the total radius of the spiral channel (from the centre of the spiral and/or the axis of (intended) rotation), of 90% or less from the centre of the spiral and/or the axis of (intended) rotation, preferably 70% or less, or 60% or less, such as a relative distance of from 10% to 90%, or from 30% to 70% from the centre of the spiral and/or the axis of (intended) rotation.

Where the reactor comprises more than one spiral channel, each spiral channel may have a corresponding means for controlling the pressure within the spiral channel, or two or more spiral channels may share one means for controlling the pressure within those spiral channels. Where there are two or more phases, the means (e.g. weir) of the more dense phase may be positioned at a greater distance from the axis of rotation compared to the less dense phase.

The common connections discussed above may be used to join together each spiral channel such that one or two means for controlling the pressure within the spiral channel(s) (e.g. weirs) can be used for multiple spiral channels.

Output unit

The reactor can comprise at least one output unit comprising an open ended conduit. The open ended conduit rotates with the or each reactor bed. The conduit is configured to form a jet of the liquid from the spiral channel such that, in use, the jet can be collected by an annular collector.

Liquid typically enters the output unit through a conduit, from the or each spiral channel. The output unit is fluidly connected to the inner or outer end of the or each spiral channel, for example via a means for controlling the pressure of the liquid in the or each spiral channel (e.g. weir). In use, the output unit rotates in unison with the spiral channel.

The or each output unit comprises an open ended conduit that rotates with the reactor bed. The conduit may, for example, be a pipe, tube, or channel. The conduit may terminate in a nozzle or spillway. The open ended conduit is arranged to form a jet of the liquid from an end of the spiral channel such that, in use, the jet can be received by an annular collector. It will be appreciated that the formation of a jet requires the open end of the conduit, through which the liquid passes to form the jet, to be relatively narrow. A dimension of the open end of the conduit in a direction parallel to the axis of rotation (e.g. in any direction) required to form a jet will depend on factors such as the rate of flow of the liquid. However, a typical dimension (e.g. diameter) of the open end of the conduit in a direction parallel to the axis of rotation (e.g. in any direction) may be 20mm or less, such as 10mm or less, or 5mm or less, preferably 2mm or less, such as 1 ,5mm or less, for example about 1.0mm. In a most preferred embodiment the open end of the conduit is a spillway with a dimension in a direction parallel to the axis of rotation of 1.0mm. Preferably the open end of the or each conduit is positioned closer to the (in use) axis of rotation and/or the centre of the spiral than the outer end of the spiral channel. This assists in avoiding stripping off a bed of particles (e.g. cells) from the spiral channel. The open end of the or each conduit may be positioned at a distance, relative to the total radius of the spiral channel (from the centre of the spiral and/or the axis of (intended) rotation), of 90% or less from the centre of the spiral and/or the axis of (intended) rotation, preferably 70% or less, or 60% or less, such as a relative distance of from 10% to 90%, or from 30% to 70% from the centre of the spiral and/or the axis of (intended) rotation.

The open end of the conduit is typically directed substantially perpendicularly to, and away from, the axis of rotation such that, in use, the jet formed from the open end of the conduit travels away from the axis of rotation to be caught by (an inner surface of) the annular collector. The open end of the conduit may be directed at an angle of ±50° or less, such as ±45° or less, preferably ±40° or less, or ±35° or less, such as ±30° or less, such as ±25° or less, such as ±15° or less from perpendicular to the axis of rotation (i.e., where the axis of rotation is vertical, from horizontal). The angle may be ±5° or more, such as ±15° or more, such as ±20° or more, or ±25° or more. The angle may be from ±5° to ±50°, such as from ±45° to ±15°, or from ±40° to ±20°. This allows the jet to be more resilient and reduces the disintegration and/or aerosolization of the jet, thereby improving the efficiency of the reactor. Generally, the smaller the angle the thinner the liquid jet is, which results in the jet being more prone to breaking up before collection. The actual angle of flight is the vector sum of the angle at the average velocity of outflow and the tangential component of rotational velocity (r * omega). Generally the latter greatly exceeds the former so the spillway angle has relatively little effect on the jet direction.

It will be appreciated that aspects of the non-rotating annular collector can be configured in a similar manner as the annular reservoir. However, it will be appreciated by the skilled person that there may be design differences between the annular collector and the annular reservoir, as the annular collector is preferably independent of the rotation of the output unit, e.g. not rotatable, whereas the annular reservoir rotates with the or each spiral channel/reactor bed.

The annular collector may (or may not) be part of the reactor. The annular collector is preferably independent of the rotation of the output unit, e.g. not rotatable. It will be understood that the inner surface of the annular collector is arranged to collect the jet. The annular collector has a curved upper section to collect the jet. The annular collector may be substantially U-shaped in cross-section. The annular collector should be configured to prevent the liquid from escaping before it can drain from the collector.

The annular collector may include an annular sidewall arranged to catch the jet formed by the output unit. The annular collector can prevent the liquid from escaping the collector as it is decelerated by impingement on the collector surface. The sides of the annular collector may be substantially shaped as a sideways U in cross-section. Preferably each side of the annular reservoir has a substantially J-shaped cross-section. Preferably the sidewall is unitary with the base.

Devices of the prior art simply expel the reaction mixture into a casing that can be collected. However, this is particularly wasteful and can introduce additional gases to the reaction mixture and/or allow volatile chemicals to evaporate. The device of the present invention preferably uses a weir and/or the open end of the conduit to bring the flow closer to the centre of rotation of the device. This allows the annular collector to have a diameter that is smaller than the outermost diameter of the spiral channel. Preferably the annular sidewall of the annular collector has a diameter that is smaller than the outermost diameter of the spiral channel.

Preferably the annular collector has an inner radius (measured up to its sidewall) that is equal to or smaller than the radius of the spiral channel. This assists with collection of the jet before it disperses (e.g. aerosolises). Preferably the annular collector has an inner radius that is 95% or less of the radius of the spiral channel, such as 90% or less, or 80% or less.

Preferably the dimension of the open end of the conduit in a direction parallel to the axis of rotation (e.g. in any direction) is 20mm or less (e.g. 2mm or less); and the annular collector has an inner radius that is equal to or smaller than the radius of the spiral channel. This assists with both the preparation of the jet and the efficient collection of the jet before it disperses.

The annular collector may comprise a top (e.g. lid) to assist with preventing liquid from leaving the annular collector once it has entered the annular collector and/or to prevent contaminants from entering the annular collector. The annular collector (e.g. the top) may have an orifice (e.g. an annular or circular orifice) to allow the entry of the liquid as the annular collector rotates. Preferably the top is unitary with the sidewall of the annular collector.

Once the jet has been caught by the collector, there is a radial deceleration of the liquid and the liquid falls under gravity into the annular collector. Flow under gravity may be aided through the use of a negative gradient (i.e. a slope from a high point to a low point). The annular collector may include (e.g. at or fluidly connected to the low point) one or more drain holes and/or a reservoir, or be fluidly connected to a reservoir. The annular collector (e.g. the U-shaped section) may be axisymmetric with the axis of (intended) rotation so that flow along the collector is driven by liquid elevation difference towards the drain hole and/or reservoir. Thus, the annular collector can collect the liquid that has passed through the reactor and store it or pass it to another component of the overall system.

Auxiliary components

The reactor may be equipped with a motor to rotate the reactor bed(s). The reactor may be equipped with a controller, for example a motor controller such as to control the rate of rotation.

The reactor may be equipped with means to monitor a reaction, for example detector such as a camera, a NIR detector, and/or a diode array detector. The reactor may be equipped with lighting (e.g. LED lighting) to illuminate the spiral channel through a cover that is at least partially transparent. Preferably the reactor has a camera configured such that the frame rate is synchronised with the frequency of rotation of the reactor. This allows a fixed region of the spiral channel to be viewed, such that photographs may be recorded for biofilm thickness measurement and/or continuous observation.

The reactor may comprise a gas-tight housing configured to meter gases into and out of the spiral channel(s).

The reactor may comprise a manifold to switch different liquid input flows. The reactor may comprise a means for controlling the temperature of the reaction conditions within the spiral channel. This can be a means for raising the temperature of the spiral channel such as a heater (e.g. thermoelectric heater) and/or a means for lowering the temperature, such as an ice bath or thermoelectric cooler. The means for controlling the temperature may comprise a conduit for temperature control fluid (e.g. water), where the temperature control fluid may be heated or cooled by external apparatus. Preferably the temperature inside the spiral channel is from 0 to 100°C, such as from 1 to 80°C, or from 5 to 50°C, preferably from 20 to 50°C, or from 20 to 45°C, more preferably from 25 to 40°C, such as from 30°C to 40°C, or from 35°C to 40°C. As the skilled person would appreciate, the temperature selected may be chosen to suit the reaction occurring. The reactor may include insulation to maintain the temperature within the spiral channels. Heat transfer and/or consequent uniformity of temperature throughout the reactor may be assisted by the flow of any gas that is generated and is driven by the rotating reactor unit within the case of the reactor.

The reactor may comprise a rotatable shaft that is configured to rotate together with (i.e. in unison with) the or each reactor bed, receiver unit and output unit. Alternatively, the or each reactor bed, receiver unit and output unit may be configured to rotate together about a stationary shaft.

The reactor may comprise gas input and/or gas output, for example with corresponding gas input conduit and/or gas output conduit. The gas input and/or the gas output may be fluidly connected to the spiral channel. The gas input conduit and/or the gas output conduit may be coaxial with the axis of intended rotation. The gas input conduit and the gas output conduit may be coaxial with one another. The gas input conduit and/or the gas conduit may be at least partially defined by the shaft. The gas input (conduit) may be fluidly connected with the outer end of the or each spiral channel (e.g. the outer common connection), and/or the gas output (conduit) may be fluidly connected with the inner end of the or each spiral channel (e.g. the inner common connection). The gas output (conduit) may additionally or alternatively be fluidly connected with (an inner end of) the means for controlling the pressure in the or each spiral channel (e.g. weir).

The amounts and pressures of gases fed to the spiral channel may be controlled by equipment such as regulators and/or valves. When introducing a gaseous phase to and/or collecting a gaseous phase from the spiral channel(s), a sealed connection is generally used on the input and/or the output to produce the required pressure difference and/or to ensure outlet gas can be collected independently.

The skilled person will appreciate that a variety of structures can be used to support the reactor and its rotating elements. The reactor may be supported at both ends or may be cantilevered. The reactor may comprise a housing, for example to contain and/or support the reactor bed. The housing may comprise one or more bearings and flanges to support the reactor bed. Where bearings and/or flanges are positioned on both ends of the reactor bed (e.g. above and below), a plurality of posts may space the flanges. The structure of the reactor housing should be designed to avoid mechanical resonances over the operating range of rotation rate.

In use the reactor may be positioned such that, and/or the reactor may be configured such that, the spiral channel is substantially horizontal and such that the axis of rotation of the reactor is substantially vertical. Preferably the axis of rotation is substantially perpendicular to the plane of the spiral channel.

The components of the reactor may be formed of any suitable material. The material may be metals, such as stainless steel, aluminium, and/or chrome, resins, Plexiglass (RTM; i.e. poly(methyl methacrylate)), glass, or a mixture thereof. The material may be a metal, such as a metal selected from the list consisting of stainless steel, aluminium and titanium, and alloys thereof. The material may be a resin, plastics (e.g. thermoplastics and/or acrylics), a glass (e.g. borosilicate glass), or composites thereof. The composites may be glass fibre and/or carbon fibre composites thereof.

Suitable thermoplastics include polyaryletherketone (PAEK), polyether ketone ketone (PEKK) and polyether ether ketone (PEEK). Other suitable plastics materials include polyetherimide (PEI), polysulfones (PPSU, PSU, PES), polyphenylene sulfide (PPS). PEEK is preferred due to its high chemical resistance and structural stability.

Priming the spiral channel

Particles may be immobilised on one or more wall of the spiral channel.

The second aspect provides a method of depositing a layer of particles within a spiral channel. The method comprises: providing a spiral channel; charging a suspension of the particles into the spiral channel; and rotating the spiral channel while the suspension is within the spiral channel. The rotation may be allowed to continue for a period of time.

Preferably the method comprises: providing a spiral channel; whilst the spiral channel is rotating, charging a suspension of the particles into the spiral channel; and allowing the rotation of the spiral channel to continue for a period of time. Preferably this method is used for the reactor of the invention, which includes receiver and/or output unit(s). Thus, the method would require that the spiral channel is rotating while the suspension is charged (e.g. injected). The rotation may be initiated before the suspension is charged. This may be necessary to force the suspension to flow through the channels rather than out of a gas vent or less dense phase outlet, depending on the particular configuration. Furthermore, charging during rotation of the spiral channel, as may be required for the reactor of the invention, can be beneficial for preventing the immobilised particles on the outer wall becoming loosened under gravity and draining between suspension injection and spin up to a rotation rate.

The method may comprise charging the suspension into the spiral channel before the rotation of the spiral channel is initiated. Where the reactor comprises seal units (as depicted in Figure 1), it has been found that it is necessary to inject the suspension before rotation has been initiated to prevent the particles settling in the seals or before the suspension reaches the spiral channel. Thus, preferably this method is used for a reactor comprising a seal unit.

The method may comprise removing the supernatant (i.e. the liquid resulting after the deposition of the particles).

The particles may be a reagent or catalyst for performing a chemical reaction. For example, the particles may be cells or agglomerations of cells. The particulates may be of carbon (e.g. activated carbon), clay, zeolite, enzymes, or cells (e.g. biofilms), for example. Particles may be loaded with a catalytic agent, such as a metal-containing catalyst.

The particles may have an average (mean) particle diameter of from lOnm or more, such as lOOnm or more, or 500nm or more, such as 800nm or more. The particles may have an average particle diameter of 100pm or less, such as 50 pm or less, or 20 pm or less, such as 10 pm or less, such as 1 pm or less. The average particle diameter may be from lOnm to 100 pm, such as from 500nm to 50 pm. The average particle diameter may be determined by laser diffraction, for example. The average may be a number, volume, surface area or other average (preferably number average).

The rate of rotation may be 100RPM or more, such as 200RPM or more, or 300RPM or more, preferably 400RPM or more, for instance 600RPM or more, such as 1000RPM or more, or 1500RPM or more. The rate of rotation may be 100,000RPM or less, such as 50,000RPM or less, or 20,000RPM or less, or 10,000RPM or less, for instance 8000RPM or less, or 4000RPM or less, or 3000RPM or less. The rate of rotation may be from 100RPM to 100,000RPM, such as from 400RPM to 100,000RPM, or from 400RPM to 20,000RPM, or from 1000RPM to 10,000RPM.

The skilled person will appreciate that, during suspension injection, a high flow rate (and thus Reynolds number) should be used to get sufficient stirring effect and high rotation rate is the most effective way to enable high flow rates. Various operations, such as cleaning out the spiral, benefit from high flow rate.

With extraction or gas generation the phase menisci are reduced at high rotation rate. This pins the sliding gas pockets against the inner wall, out of the way of the particle bed, and makes the extract layer more uniform and, hence, places the phase interface an equal distance from the particle bed at all locations.

The method may comprise filling the spiral channel with the suspension through the inner end of the spiral channel. The method may comprise closing the outer end of the spiral channel before the suspension is charged - this can be achieved because the rotation allows the gas originally in the spiral channel to pass by the incoming suspension, preventing gurgling and restriction of the inward flow of the suspension. The positioning of the outlet weir required for reactor operation ensures that the suspension will be contained, provided that the injected volume of suspension matches the volume of the spiral channel and outlet passage leading to the outlet weir. When multiple spiral channels are in operation the suspension volume should substantially match combined volume to fill all channels. Preferably the volume of suspension charged to the reactor is approximately the same as the volume of the spiral channels of the reactor (e.g. differing from the actual volume by ±10%, or ±5%, or ±2% by volume).

The period of time enables the particles to sediment on the outer wall of the spiral channel. The method may comprise keeping the outer end of the spiral channel closed during the period of time for which the particles are allowed to sediment under rotation. The period of time may be 1 second or more, such as 5s or more, or 10s or more, such as 15s or more, or 20s or more, such as 30s or more. The period of time may be 24 hours or less, such as 10 hours or less, or 1 hour or less, for example 10 minutes or less. The period of time may be from Is to 24h, such as from 10s to lOh, or from 15s to Ih.

It has been determined that by filling the spiral channel with a suspension while the spiral channel is rotating, the spiral channel is filled efficiently and effectively, with minimal gurgling of air back through the spiral channel. The rotation of the spiral channel provides a centrifugal force that acts upon the particles and deposits the particles in a layer on the outer wall of the spiral channel.

For example, a particulate (e.g. yeast) can be used as a biocatalyst for a reaction to convert a precursor material to an end product. The particulate (e.g. yeast) can be introduced to and immobilised onto the spiral channel before the precursor material is introduced. The particulate (e.g. yeast) material is thus contained within a film (e.g. biofilm) immobilised onto the spiral channel (i.e. one or more walls of the spiral channel). The spiral channel is pre-coated with the particulate (e.g. yeast) containing film (e.g. biofilm) in advance of the precursor material being added to the spiral channel. This may be done some time in advance of the precursor material being added, or preferably it is done as the first step in the process just prior to addition of the precursor material. For example, a preferred first step is to coat the spiral channel with the film (e.g. biofilm) material (otherwise known as particle bed material), this is preferably done under high speed of rotation (at speeds of 200RPM or more, such as 300RPM or more, or 400RPM or more), while the volume of the material ideally is matched to the volume of the available spiral channel. The rotation allows the particulate (e.g. yeast) material to backfill the spiral channel and to settle into a coating film (e.g. biofilm) on the spiral channel (e.g. one or more walls thereof). The priming of the spiral channel may provide a spiral channel with a layer of the particles on the outer wall of the spiral channel. The layer may be lOnm thick or more, such as 1 pm thick or more, such as 10 pm thick or more, such as 100 pm or more, or 200 pm thick or more. The layer may be 5mm thick or less, such as 1 mm or less, such as 500 pm or less, or 400 pm or less, such as 300 pm or less. The layer may be from 10 nm to 1mm thick, such as from 1 pm to 500 pm thick. The primed spiral channel may or may not contain a liquid.

Reaction conditions

It will be appreciated that almost any reaction can be performed in the claimed reactor.

It will be appreciated that the reactor may be used for reactions that involve two or three or more different phases. For example, the rotating spiral reactor may facilitate reaction and/or mixing between two different gaseous phases; a gaseous phase and a liquid phase; a gaseous phase and a solid phase; two different liquid phases; and/or a liquid phase and a solid phase. The reactor may be used for tri-phase systems such as liquid- liquid-solid system and/or gas-liquid-solid systems, or for quad-phase systems: liquid- liquid-gas-solid. A solid phase may coat substantially all of the inner surface of the spiral channel and/or may coat only part of the inner surface of the spiral channel (e.g. the outermost wall of the spiral channel).

The reactor may be loaded (e.g. pre-loaded) with a solid phase forming a layer on one or more walls of the spiral channel. Preferably any solid phase is present on the outer wall of the spiral channel. Solid reactants may be loaded onto the reactor via injection of a suspension onto the receiver unit. Such a suspension may, for example, be injected using a syringe (e.g. driven by a syringe pump) into the receiver unit.

Detailed Description of the Drawings

Figures 1 and 2 of the accompanying drawings are described in the Background section above. Figure 1 shows a conventional setup for connecting input and output fluid streams to a rotatable reactor. Figure 2 shows a rotatable reactor 20 that includes a reactor bed 28 that has a spiral channel. It will be appreciated that the requirements of the claimed invention can be combined with conventional means for introducing fluids to the spiral channel(s), as described in relation to Figures 1 and 2. Figure 3 of the accompanying drawings displays reactor 30 of the present invention. Reactor 30 has a reactor bed 32; motor 34, to drive the rotation of the reactor beds; flow valves 36, to control the liquid inlet(s); product outlet(s) 38, which can be used for sampling; motor controller 300 to control the rotation speed; thermocouple 302, which is inserted into the collector through the bottom flange of the casing to determine the temperature of the reactor; and camera 304 to monitor the reaction under illumination from light 306. Motor controller 300 allows camera 304 and light 306 triggering to be synchronised with the rotation of the reactor bed 32.

Figure 3 shows the main features of the rotating spiral reactor. Electronics (motor 34, motor controller 300, camera 304 and LED light 306) are on top along with liquid inlet and vent. Also on the top is a bracket to mount valves needed to switch the inlet between media flow, inoculant (suspension) injection and air (part of flow valves 36). Three cylindrical posts 308 space top flange 3000a and bottom flange 3000b, which house shaft bearings and the seals (not shown) to protect the bearings from liquid and to prevent leakage from the case during device sterilisation using liquid solutions. Figure 3 shows the rotating spiral reactor without the side in place, so that the rotating unit can be seen.

Figures 4A and 4B of the accompanying drawings displays reactor 40 of the present invention. Figure 4A shows that reactor 40 has motor 42; controller 44; camera 46; light emitting diode (LED) light 48; selection valves 400; case air bleed/vent 402; compressed air inlet 404; liquid feed bottle 406; dual syringe pump 408; check valve network 4000; back pressure valve 4002; inlet heater 4004; reactor outlet 4006a; case drain 4006b; case overflow 4006c; waste drain 4006d; and inoculation pump 4008.

Figures 4A and 4B show a broader arrangement that includes auxiliary equipment for reactor 40, including syringe pump 4004 for injecting inoculant, dual syringe pump 408 combined with a check-valve network 400 to allow continuous media flow over long periods of time and compressed air connections 404 both to apply pressure for rapid draining of cleaning liquids and to supply bleed air to oxygenate the liquid. Reactor 40 also includes camera 46 to allow photos of the spiral channel to see the deposition of the biofilm material. It will be understood that dual syringe pump 408 can be replaced by a continuous pump, and heat exchangers may be added (e.g. to the top and bottom flanges) to control the temperature of the reactor (e.g. the temperature within the spiral channels).

Figure 5 of the accompanying drawings shows a cross-section through reactor 50 of the present invention, which reveals the inner workings of reactor 30, 40 as shown by Figures 3 and 4. Reactor 50 has liquid inlet tube 52; feed reservoir (annular reservoir of the receiver unit) 54; inner connection 56; spiral channel 58 in reactor bed 580; outer connection 500; weir 502; open channel 504; spillway 506 and collector/drain 508. Fluid flow path A is shown passing through reactor 50 from liquid inlet tube 52 to spillway 506. Reactor 50 is supported at both ends of the rotatable axis.

Figure 6 of the accompanying drawings shows a cross section through reactor 60 of the present invention, in a similar manner to Figure 5. Reactor 60 has six reactor beds 62. Each reactor bed 62 has one spiral channel 64. Spiral channels 64 are connected in parallel with one another. Figure 6 also illustrates motor 66 used to rotate the reactor beds.

Reactor 60 includes extraction flow capability in a 6-stack contactor. It can be used with particles, and to perform a reaction with simultaneous extraction.

Figure 6 shows inlet tubes 68 into reservoirs 600 (one for each liquid phase) and the connecting passages for the lowermost spiral channel 62 from reservoirs 600 and from that spiral channel, at either end, to the respective phase outlets. The other five spiral channels are serviced in the same way by connecting passages at 60 degree angle intervals around the axis of rotation of the reactor. The spillways that form the liquid streams into the receiver are not shown. Reactor 60 includes annular receiver scoops 602 (one for each liquid phase) that feed into drain channels 604 (one for each liquid phase, only one of these is shown). Drain channels 604 sweep from a high point down to a drain outlet over 180° in both directions from the high point. The skilled person will appreciate that the slope and the width of drain channels 604 can be optimised for the desired flow rate. Reactor 60 is cantilevered (i.e. supported at one of the two ends of the rotatable axis).

As shown by Figure 6, the flows from the six weirs of each phase outlet empty into two spillways. Combining the flows from multiple weirs into the same spillway and/or increasing flow rates, as when cleaning out particles, the user can preserve more of the angular momentum in the annular collector, and this can help to sweep out debris in the collector.

A reactor having a design very similar to that of reactor 60 has been successfully used for counter-current two phase flow in practice. Deionised water was used as the heavy (more dense) phase and was fed to the heavy phase receiver. All six channels were filled equally with the water. Butanol (e.g. n-butanol) was used as the light (less dense) phase and the flow of the light phase was subsequently introduced.

With both the deionised water flow and butanol flow into the light phase receiver, the water flowed from the inner end to the outer end of the spiral channels and on to the heavy phase collector and the butanol flowed from the outer end of the spiral to the inner end (in counter-current flow) and on to the light phase collector. It was confirmed that only water exited from the heavy phase collector and only the butanol phase exited from the light phase collector at all times throughout a run from starting the flows through to a steady state of operation.

Figures 7A-C of the accompanying drawings shows cross-sectional views of reactor 70 that is an alternative design of a reactor of the invention. Figure 7A shows weirs 72, and Figure 7B shows spillways 74 and drain 76. Reactor 70 includes two weirs 72, two spillways 74 and one drain 76 for each liquid phase. Figure 7C shows a plan view of spiral channel 78 in reactor bed 700. Overall, Figure 7 further illustrates the fluid flow path through a reactor of the invention.

Figure 8 of the accompanying drawings is a photograph of reactor 70 as illustrated in Figures 6 and 7.

Figures 9A-F show schematic cross sectional representations of different configurations of reactors of the invention. 5 spiral channels are shown in each case, although the fluid connections are only shown for one spiral channel. The spiral channels appear staggered in cross section due to the rotational displacement between the channels.

Figure 9A of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figures 6 and 7. Reactor 90 is configured to handle one liquid phase. There may be a particle bed (i.e. solid phase) on the outside wall of the channel.

In use, the spiral coils are positioned substantially horizontally, and the axis of rotation is substantially vertical. As shown in Figure 9A, at the top, the liquid is fed through inlet tube 92 such that the liquid is deposited onto the platen 94a of the rotating feed reservoir 94b. Due to the rotation of feed reservoir 94b, the liquid is accelerated towards the outside edge of feed reservoir 94b. The liquid joins the reservoir liquid, filling to position “a” that is dependent on factors such as the weir position and the liquid feed rate.

The liquid flows down through vertical conduit 96a to the inner end of a spiral channel 98, through spiral channel 98. Only one of the five spiral channels 98 shown is depicted as being connected to the vertical conduit 96a, but all of the spiral channels are (fluidly) connected to the feed reservoir 94b. After travelling through spiral channel 9the liquid flows down vertical connection 96b to radial channel 900 returning the liquid to the radial position of weir 902 and then down vertically over weir 902. Each of the spiral channels 98 shown are connected to a separate weir 902. Each weir 902 establishes a fixed hydrodynamic datum “d” (of combined pressure, gravity and centrifugal energy) which the reservoir level at the top (a) is forced to exceed by an amount depending on frictional losses in the spiral flow in order to establish a flow of the liquid through the spiral channel. Having a weir for each spiral channel, rather than having a weir to serve multiple or all spiral channels, prioritises design simplicity as the structures are simply repeated every 360/n degrees, for n spiral channels, with the spiral channels arranged on different reactor beds in the stack. Also, the identical flow path for each spiral channel in the stack resulting from this approach encourages more equal distribution of flow to the spiral channels and may better suit structural requirements.

Once over the weir, the liquid flow enters spillway 902 directly (although an annular open channel may be used to convey the liquid to spillway 902), which results in the liquid being formed into a liquid jet. The jet is caught by the cupped wall of a fixed annular collector 904. The bottom of the annular collector is sloped from a high point downward in both directions to a drain outlet, which is the outlet from the reactor and this leads to a sampling arrangement (shown in and described in relation to Figure 7B). The flow diagram in Figure 9A is a depiction of the flow network of the rotating spiral reactor. Liquid is input into the system through the liquid inlet tube 92, this liquid fills the feed reservoir 94b, the liquid travels down the inner connection to enter the spiral channel at its inner end “b”, and exits the spiral channel at its outer end “c”, and then proceeds through an outer connection to the weir 902.

A gas outlet (vent) at the inner end of the spiral “g” is included to allow displaced gas to exit during particle suspension injection to form the bed and to allow any gas pockets that built up to escape. The vent also enables any trapped or generated gas to escape without disruption of the liquid inlet flow. Where the reaction depends on a gas species absorbed into the liquid, this may be achieved by saturating the gas within the receiver unit. This is positioned more centrally than the inner end of the spiral channel, weir 902 and reservoir level “a” to avoid liquid loss through the gas vent.

Where fluids are not being transferred into/out of the spiral channel(s) using the receiver/output units, syringe pumps (e.g. dual syringe pumps, for example combined with a check-valve network) and/or gas regulators may be used to control the input of fluids using systems such as that depicted in Figures 1 and 2.

The rotating spiral channel allows a biofilm to be stabilised by centrifugal acceleration, to be continuously supplied by a sustaining media and the possibility of product concentration moderation by extraction with a parallel-flowing solvent.

The reactor of the present invention may be equipped to handle two fluid phases (e.g. of different densities). The acceleration caused by the rotation of the spiral channel allows a denser phase to be stabilised on the outer side of the spiral channel. In other words, the denser phase is stabilised by centrifugal acceleration. The denser phase may be continuously supplied with a second less dense phase (e.g. through the course of a reaction). The concentration of the product in the denser phase may be moderated or controlled by extraction with a parallel- or counter-flowing solvent (e.g. where the solvent has a lower density).

Figure 9B of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figure 9A, where the reactor is configured to handle single-phase media flow with gas output. The gas may be generated by the reaction performed within the reactor, for example.

Figure 9B shows an axial conduit in the shaft to allow uncontaminated outflow of the gas, which may be collected. The gas slides up the spiral channel in ‘pockets’, but also is partly absorbed into the media and this leads to gas formation in the radial media outlet channel as pressure decreases along that channel.

Figure 9C of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figure 9A, where the reactor is configured to handle single-phase media flow with gas input and gas output.

Higher levels of supplied gas than are possible by saturating the inlet media at the platen require the gas to remain in contact with the media along the length of the spiral channel. This can be achieved by incorporating a gas inlet conduit (“bleed”) that is fluidly connected to the outer end of the spiral channel. This can be achieved using a tube that is coaxial with the gas outlet hole in the shaft, which usually requires a rotating seal.

Figure 9D of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figure 9A, where the reactor is configured to handle two liquid phases and that flow counter-currently. This is exactly that type in Figs. 6 and 7 (though with 5 (not 6) spiral channels). This reactor may be used to extract a component (e.g. solute) of one phase into the other phase. Extraction flow has been demonstrated under reactors based on this design where either bacteria or yeast are used as the solid phase. It will be appreciated that an adjustment reservoir may be placed at either end of the spiral channel, according to which interface position is used (large or small interface position in the spiral channel). The reactor has two reservoirs with input levels “a”, “e”; two weirs with levels “<7”,

Figure 9D illustrates “breaking the gravity link” whereby uniform amounts of each phase are distributed to each spiral channel in the reactor. The outlet passage for the light (i.e. less dense) phase is extended up from each light phase weir at common datum position up to the top of the stack where each heavy (i.e. more dense) phase inlet ends. This column is sized to make frictional losses negligible in the column of light phase liquid that it forms. This achieves two conditions: Firstly, the pressure at each of the heavy phase feed outlets is the same (equal to the hydrostatic pressure rise from the case pressure at “f ’ to that at the top of the light phase liquid column) and, since the flows are driven also from the same reservoir datum through identical passages from “a”, the individual heavy feed flows will be equal.

Secondly, the pressures at “b” and “c” which affect the flow rates through each spiral channel increase as we move from channel to channel vertically down the stack because of hydrostatic pressure increase. But because fluid of uniform (light phase) density is the cause, the pressure difference between “b” and “c” remains constant and that is what drives flow.

The roles of the two phases may be reversed to achieve the alternative interface position in the spiral channel section (for liquid-liquid flow there are always two unique positions for the same two phase flow rates). So the static column may extent up from weir “d” to the top of the stack, containing heavy liquid this time. The adjustment interface at “g” will be accommodated instead, in a similar way, at the inner end of the spiral.

A single-element version of the 6-channel design shown in Figure 8D has been operated successfully over a range of extract liquids, rotation rates and flow rates contacting with water as the heavy phase. Reactors of the invention have been successfully used with extract liquids of butanol, octanol, isopropyl myristate or oleic acid. The successful use of oleic acid, which has a viscosity of 28 times higher than water, demonstrates that highly viscous liquids can surprisingly be tolerated by the reactor of the invention.

Figure 9E of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figure 9D, where the reactor is configured to handle two liquid phases and that flow counter-currently (e.g. for extraction) with gas output (e.g. by generation).

Gas escape passages (i.e. vents) can be added as before to allow for gas generation with extraction. The gas pockets will slide up the spiral channel as before, but now will slide with the extract liquid layer. So, there is a complex flow pattern in the two liquid phases.

Figure 9F of the accompanying drawings shows a cross sectional schematic view of a reactor similar to that shown in Figure 9A, where the reactor is configured to handle two liquid phases and that flow counter-currently (e.g. for extraction) with gas input, and gas output.

The reactor design is similar to that shown in Figure 9E, but with a gas feed. This could be supplied using a bleed of gas at the outer end of the spiral channel. A tube that is coaxial with the gas outlet hole in the shaft is needed and this requires a rotating seal, as described in relation to Figure 8C.

Figure 10 of the accompanying drawings shows a cross sectional schematic view of a reactor with reactor beds A-C, each reactor bed having multiple (five) spiral channels. Each bed feeds the next bed with addition of some new reagent material as liquid reagents A-C. Each reactor bed may contain a different solid phase (e.g. particle/cell type).

Examples

The claimed reactor may be used to perform reactions, such as the synthesis of esters, fatty acid esters, alcohols, and/or sesquiterpenes. These materials are commonly used as fragrance materials and as such are high value materials, though the routes to produce these materials are often lacking.

Example 1

With a ‘rose-like’ aroma, 2-phenylethanol (2PE) is an important molecule in the flavour and fragrance industries. Traditional 2PE production methods involve its extraction from the essential oils of many flowering plant species - most notably, rose oil, which contains up to 60% 2PE. Although extraction is still practiced to obtain the natural product, as said process is expensive and poorly scalable, the bulk of 2PE production now instead occurs via its chemical synthesis from petrochemical feedstocks. Though cheaper, 2PE production in such manner is both non-renewable and unsustainable, and furthermore employs carcinogenic precursors (i.e., benzene) as feedstocks. Alternatively, 2PE can be produced via microbial fermentation using established biotechnological methods or extracted from rose petals. However, conventional biotechnological methods result in low yield of 2-phenylethanol often due to concentrations beyond 2 g/L being toxic to the microorganisms. Further, extraction from rose petals relies on the use of a lot of land to grow the roses and typically it takes over 30,000 rose petals to generate < 1 kg of the oil and a prohibitive cost.

Gao and Daugulis report production rate results for a CSTR (continuously stirred-tank reactor) with and without ISPR (in situ product removal) using the yeast strain, Kluyveromyces marxianus (CBS 600). Without product removal, which is the typical situation in current industrial practice, the specific production rate is 0.05 g/L/h and with product removal 0.43 g/L/h. (Gao, F. and A. J. Daugulis, 2009, Bioproduction of the Aroma Compound 2-Phenylethanol in a Solid-Liquid Two-Phase Partitioning Bioreactor System, Biotechnology and Bioengineering 104:2, 332-339).

Using a reactor of the present invention, production rate of the end product can be increased by an order of magnitude compared to conventional manufacturing processes using continuous stirred tank reactors.

Much higher particle loadings can be achieved in the spiral bioreactor compared to conventional manufacturing processes using continuous stirred tank reactors, which leads to much higher production rate of the end product.

Another advantage of the spiral bioreactor over conventional stirred tank continuous flow reactors includes enhanced productivity by precise control of mass transfer conditions, inherent control of reactor temperature uniformity and simultaneous removal of product species, this can also allow easier and faster product removal, so limiting any negative influence of the product on the system, e.g. if the end product poisons the reaction or organism used.

The reactor is also able to handle gas phases, whether produced in another phase and/or purposefully introduced into the reactor, as the (less dense) gas phases travel up the inner side of the spiral channel and can be removed through a vent.

The reactor of the present invention has been used with biofilms. Syringe pumps are used to drive both the media and the extraction solvent flows. The liquid (media) is saturated with oxygen to supply the yeast. The passages were sterilised using 20 g/L sodium hypochlorite solution (10 min) followed by 50 g/L sodium thiosulfate solution (10 min) and then filled with liquid (media). The initial biofilm is formed from inoculant suspension injected along the media flow path to fill the spiral channel and passages leading to and from it and then, using a sequence of valve opening and closing, the inoculant remaining in the connecting passages is removed and replaced with media. Then rotation is started to force the cells in suspension to settle to the outer wall of the spiral channel forming a sediment layer, i.e. the biofilm.

Figures I la and 11b of the accompanying drawings show photographs of a spiral channel of a reactor of the prior art, as shown by Figures 1 and 2. Figure 11b is an enlarged and annotated version of a section of Figure I la. The spiral channel contains a 280pm thick biofilm of Kluyveromyces marxianus on the outer wall. The biofilm was formed by settling under centrifugal acceleration of 50g. The biofilm can be clearly seen in Figure 1 lb. The thickness of the biofilm is 280pm and extends over the 79cm length and 4mm depth of the spiral channel; the width of the spiral channel is 1.5mm.

Figure 12 of the accompanying drawings shows the increased 2-PE production rate per reactor volume achieved with the spiral bioreactor used in the invention (circle symbols; reactor shown in Figures 3-5) at a settled temperature of 33°C, compared to the continuous stirred-tank reactor (CSTR) results (dashed lines) with and without in-situ product removal (ISPR) of Gao and Daugulis (2009) at a temperature of 35°C. Regarding the prior art method of Gao and Daugulis, the results in Figure 12 are shown both for CSTR without product removal, which is the typical situation in current industrial practice, the specific production rate is 0.05 g/L/h (lower of the dashed lines) and for CSRT-ISPR with product removal 0.43 g/L/h (higher of the dashed). All results used the same yeast strain, Kluyveromyces marxianus (CBS 600). The x-axis shows time, measured in minutes, the y-axis shows production rate per unit volume of the reactor, measured in g/L/h (grams of 2PE per hour, per litre of reactor volume).

The end products of the process of the Invention are selected from esters, fatty acid esters, alcohols, and sesquiterpenes. Preferred end products of the process of the invention are selected from ethyl acetate, isoamyl acetate, isoamyl alcohol, benzaldehyde, 2-phenylethylacetate, 2-phenylethyl butyrate, phenylethyl propionate, 2- phenylethanol, and sesquiterpenes. More preferred end products of the process of the invention are selected from ethyl acetate, isoamyl acetate, isoamyl alcohol, benzaldehyde, 2-phenylethylacetate, 2-phenylethyl butyrate, phenylethyl propionate and 2-phenylethanol. The most preferred end products is 2-phenylethanol.

Suitable yeast strains for producing the aforementioned end products include Clavispora lusitaniae, Kluyveromyces marxianus, Kluyveromyces sp., Kluyveromyces dobzhanskii, Saccharomyces cerevisae, Torulaspora delbruekii, and non-Saccharomyces yeast from A gave durangensis .

Preferred sesquiterpenes producible by the process of the invention include a- Farnescene, P-Farnescene, Trans-Nerolidol, a-Santalol, Patchulol, Longifolene, a- Humulene, Elemol, Cedrol, Cubenol, Guaiol, a-Agarofuran, -Agarofuran, Aristolene, Muurolene, Valencene, and Nookatone. These can be suitably produced using the yeast Saccharomyces cerevisiae (a-Farnescene to Muurolene), and Yarrowia lipolytica (Valencene and Nookatone). The end product sesquiterpenes a-Farnescene and P- Farnescene can be suitably produced by either of Saccharomyces cerevisiae or Yarrowia lipolytica.

The precursor materials for the input streams are usually selected according to the desired end product. The precursor materials can be generally added to the spiral bioreactor as part of a growth media composition, which can additionally comprise materials to assist the conversion reaction.

The growth media is generally specific to the yeast and the reaction to be converted, this knowledge is readily available in the art. The reaction and media are already known, it is the application of these known reaction pathways in the spiral bioreactor compared to the conventional continuous stirred tank reactor that provides the advantages of the claimed process.

An example growth media composition for the conversion of L-phenylalanine (L-PA) to 2-phenylethanol (2-PE) using the yeast Kluyveromyces marxianus (CBS 600) is: glucose, L-phenylalanine, magnesium sulfate, citric acid, potassium phosphate dibasic, yeast nitrogenous base without amino acids and ammonium sulfate, sodium acetate buffer. The liquid growth media comprising the precursor material can suitably be pre-treated with a gas selected from air, oxygen and/or carbon dioxide. This pre-treatment may be advantageous in preparing the growth media for the reaction with the biocatalyst.

The product is easily obtained from the spiral bioreactor via a liquid outlet. Such an arrangement can allow for sampling of the outflow to see the amount of product vs reactants and the flow rate can be adjusted accordingly. In a different but preferred embodiment, the spiral bioreactor is arranged with a counter-current flow (parallelflowing) of extract liquid to increase yield by removal of product species. Examples of such extract liquids used in counter-current flow are isopropyl myristate, oleic acid and decane.

Examples 2-5

Four experiments (Table below) have been completed with a reactor as shown in Figure 3, using the same yeast and media system as discussed above. These experiments have successfully produced some basic performance data that demonstrates that this device behaves as expected, confirming successful transition from the seal-based phase transfer design to seal-free transfer. Generally, the tests used the same inoculant cell density, rotation rate and method of oxygenating the feed media, but in each a different media flow rate was used.

The first three experiments were conducted at 2400RPM, i.e. higher than in the baseline tests, which increases the spiral pressure and hence CO2 capacity and also allows stability at higher flow rate than in the baseline tests. This is important since higher flow rates were needed to absorb CO2 from the 2.37 times larger biofilm surface area of the this spiral than the previously used spiral (this spiral length is 2.5 m and channel width is 3 mm compared with 0.79 m and 4 mm for the previous spiral). At 2400RPM, this spiral temperature settled at around 38 °C, the spiral outlet pressure is 1.79 bar and, for these conditions, from using the conservative value for CO2 generation rate (A = 140 pmol/mL/min) the minimum media flow rate is calculated to be 4.8 mL/min for a 200 pm thick yeast biofilm. From the table, all but one of the experiments at 2400RPM used flow rates higher than this value and, as expected, gas formed in the spiral channel only for the case that did not (2 mL/min).

Example 6

Figure 13 of the accompanying drawings shows a bed of watermelon seed powder with deionised (DI) water flow in a spiral channel of a reactor as shown in Figures 3-5.

Analysis of the image suggests a bed depth uniformity of within 10%.

Initial watermelon seed powder bed thickness following suspension injection is shown in Figure 14 of the accompanying drawings. Figure 14 shows that settling of the suspension is proportional to particle fraction.

Example 7

Figure 15A of the accompanying drawings shows the growth of an initial bed of Kluyveromyces marxianus yeast cells in a spiral channel of a reactor as shown in Figures 3-5.

Figure 15B of the accompanying drawings shows the growth of Kluyveromyces marxianus yeast cells at the end of an 8hr 2PE production run in a spiral channel of a reactor as shown in Figures 3-5. Example 8

Figure 16 of the accompanying drawings shows oxygen gas production in a bed of watermelon seed powder in a spiral channel in a reactor as shown in Figures 3-5. Gas pockets may be observed on the inner wall of the spiral channel and then slide up the channel when they reach a critical size. Flow of a 7.4 mM H2O2 aqueous solution at 1.1 mL/min produced gas during 5hr of continuous operation at 2400RPM.

Example 9

Figures 17A and 17B of the accompanying drawings demonstrates operation of a comparative reactor as shown in Figures 1 and 2 with a bed of Kluyveromices marxianus yeast cells in a spiral channel, with media flow and counter-current flow of decane, both for the thin media mode (Figure 17A) and the thick media mode (Figure 17B).

Example 10

Figure 18 of the accompanying drawings demonstrates operation of the 6-spiral reactor (shown in Figures 6 and 7) using butanol as extract liquid. The photograph shows the interface held steady in the adjustment reservoir at the outer end of the bottom-most spiral channel. The spiral channel connects at the lower left of the image; the heavy phase (water) exits from the connecting tube that is out of focus in the foreground; the light phase enters through the connection at the lower right of the image (behind the heavy phase connection tube) and flows counter-currently up the spiral channel.

Figure 19 of the accompanying drawings is a graph with data relating to the butanol- water interface position (using the reactor shown in Figures 6 and 7) in the adjustment reservoir over a range of rotation rate for equal liquid phase flow rates of 0.19 mL/min/channel in the 6-spiral reactor. The model predictions used to design the adjustment range of the reactor are shown for comparison. The good agreement at 0. 19 mL/min/channel allows confidence in predictions at other flow rates and for other extract liquids having different densities and viscosities, but also for other spiral designs of the invention.

The similarity of the appearance of phases in reactors according to the invention (e.g. as shown by Figures 3-5 and 12-16) and those using seal units (e.g. as shown by Figures 1, 2, 11 and 17) demonstrates that substantially the same benefits of using a spiral reactor can be achieved without requiring sealed connections to provide or remove one or more liquid phases from the reactor. This provides significant benefits in terms of efficiency and ease of maintenance, for example.

Example 11

A four-day test was performed in a reactor of the invention using yeast cells to produce a fragrance molecule. Reactor temperature: 33°C; media flow rate: 3.3 mL/min; rotation rate: 2400 rpm. Images were taken of the spiral channel at regular intervals.

The images showed the initial bed of cells growing and developing towards a steady state of continuous operation. By the end of day 1 the bed was thick enough for CO2 generated by the yeast not to be fully dissolved in the liquid phase and gas pockets could be seen on the inner wall of the channels. These gas pockets intermittently slid up the inner wall of the channel to a vent at the inner end of the spiral channel. Beginning from a uniform bed formed by cell suspension injection, the bed grew while remaining uniform during the first day, and reached a thickness for which flow stresses due both to media flow and the counter-flowing gas pockets began to promote drifting of the bed.

This shows reactors of the invention can maintain a bed of solid particles (e.g. cells), and can readily handle gas (e.g. produced by a reaction in the spiral channels).

This shows that reactors of the invention can maintain operation over a period of at least four days.

Example 12

Figure 20 of the accompanying drawings shows the variation in bed thickness (log scale) over 60 hours during two runs at different rotation rates: 2000rpm and 2400rpm. In both cases, bed growth rate receded with time as cells adapted to being resident in the bed. The irregular bed thickness at later time points was due to the passage of cell drifts. This shows that rotation rate can control the bed thickness. Higher rates of rotation may attenuate the drifts as irregular bed thickness began later in the example using a high rate of rotation.

Claims

1. A rotatable reactor comprising at least one reactor bed that comprises a spiral channel, wherein the spiral channel extends from an inner end to an outer end, and wherein the reactor comprises: a) at least one receiver unit comprising an annular reservoir, wherein the receiver unit rotates with the or each reactor bed, and wherein the annular reservoir of the receiver unit is configured to receive a liquid from a non-rotating source and transfer the liquid to the spiral channel; and/or b) at least one output unit comprising an open ended conduit, wherein the conduit rotates with the or each reactor bed, and wherein the conduit is configured to form a jet of the liquid from the spiral channel such that, in use, the jet can be collected by a nonrotating annular collector.

2. The rotatable reactor of claim 1, wherein the reactor further comprises a means for controlling the pressure of liquid in the spiral channel.

3. The rotatable reactor of claim 2, wherein the means for controlling the pressure of liquid in the spiral channel is a weir fluidly connected to an end of the spiral channel, wherein the crest of the weir is positioned closer to an axis of intended rotation and/or the centre of the spiral defined by the spiral channel than the end of the spiral channel to which the weir is connected.

4. The rotatable reactor of claim 2 or claim 3, wherein the reactor comprises more than one spiral channel, and wherein each spiral channel has a corresponding means for controlling the pressure of liquid within the spiral channels.

5. The rotatable reactor of claim 4, wherein the rotatable reactor further comprises a conduit connecting the inner ends of the spiral channels and/or a conduit connecting the outer ends of the spiral channels.

6. The rotatable reactor of any preceding claim, wherein option b of claim 1 applies, and wherein the open end of the or each conduit is positioned closer to the (in use) axis of rotation and/or the centre of the spiral than the outer end of the spiral channel.

7. The rotatable reactor of any preceding claim, wherein option b of claim 1 applies, and wherein the maximum dimension of the open end of the conduit in a direction parallel to the axis of rotation is 2mm or less.

8. The rotatable reactor of any preceding claim, wherein the reactor comprises two receiver units and two output units.

9. The rotatable reactor of any preceding claim, wherein option a of claim 1 applies, and wherein the annular reservoir comprises a continuous annular sidewall.

10. The rotatable reactor of any preceding claim, wherein the or each receiver unit, spiral channel, reactor bed and output unit are all coaxial with one another.

11. The rotatable reactor of any preceding claim, wherein the reactor comprises at least one delivery unit configured to provide liquid to the at least one receiver unit.

12. The rotatable reactor of any preceding claim, wherein option b of claim 1 applies, and wherein the reactor comprises one or more annular collectors.

13. The rotatable reactor of claim 12, wherein the or each annular collector has an inner radius that is equal to or smaller than the radius of the spiral channel.

14. The rotatable reactor of any preceding claim, wherein the reactor is configured to withstand accelerations of 50g or more.

15. The rotatable reactor of any preceding claim, wherein the reactor comprises a gas input conduit and/or a gas output conduit.

16. The rotatable reactor of claim 15, wherein the gas input conduit and/or the gas output conduit is coaxial with the axis of intended rotation.

17. The rotatable reactor of claim 15 or claim 16, wherein the gas input conduit is fluidly connected with the outer end of the or each spiral channel, and/or the gas output conduit is fluidly connected with the inner end of the or each spiral channel.

18. A method of depositing a layer of particles within a spiral channel, wherein the method comprises the steps of:

• providing a spiral channel;

• charging a suspension of the particles into the spiral channel; and

• rotating the spiral channel while the suspension is within the spiral channel, such that the layer of particles is deposited within the spiral channel and a supernatant remains in the spiral channel.

19. The method of claim 18, wherein the method comprises:

• providing a spiral channel;

• whilst the spiral channel is rotating, charging a suspension of the particles into the spiral channel; and

• allowing the rotation of the spiral channel to continue for a period of time, such that a layer of particles is deposited within the spiral channel and a supernatant remains in the spiral channel.

20. The method of claim 18 or claim 19, wherein spiral channel is the spiral channel of a reactor as defined by any one of claims 1-17.

21. The method of any one of claims 18 to 20, wherein the method further comprises removing the supernatant.