Field of invention

The present invention relates to a modular fluid flow reactor and a method of directing a flow of a fluid through a reactor that comprises a plurality of connectable modules, with each module adapted to create at least one fluid flow characteristic.

Background art

Flow reactors, alternatively termed continuous reactors, provide for a continuous flow of materials or reactance and enable different experimental configurations with regard to mixing properties, temperature control, monitoring, residence times etc. Example prior art flow reactors are typically formed as an assembly of individual modules that are connected face-to-face to form a unitary block through which a fluid is directed. Example flow reactors are described in DE 19917398; WO 2007/112945; US 7,726,331 ; WO

2004/089533 and WO 2013/050764. However existing flow reactors, whilst providing a means to control reaction conditions to facilitate chemical and biological synthesis, are disadvantageous for a number of reasons. In particular, existing system typically require long residence times to minimise side reactions and/or are difficult to‘ scale-up’ from initial laboratory prototypes to large industrial installations suitable for bulk synthesis and processing. Accordingly, what is required is a modular flow reactor that addresses at least some of these problems.

Summary of the Invention

It is an objective of the present invention to provide a modular fluid flow reactor and method of directing and controlling fluid flow that can result to improved heat and mass transfer and as a result reduce the time a fluid mixture would require to complete for example a chemical transformation and thus reduce the‘residence time’ of the fluid mixture. It is a further objective to provide apparatus and method to be continently‘up- scaled’ to be suitable for a large variety of fluid mixtures and large volume industrial applications.

It is a further specific objective to provide a flow reactor configured to direct and control fluid flow through the modules in order to achieve one or more specific fluid flow characteristics that facilitate the objective use of the apparatus including for example chemical synthesis, biological reactions and the general mixing of fluids.

The objectives are achieved by providing a modular flow reactor and method of directing fluid flow in which the reactor is formed from a plurality of individual modules each having a fluid flow passageway that is curved in the lengthwise direction of the

passageway. Preferably, the passageway is continuously curved and/or is curved along the majority of the length of the passageway between respective inlet and outlet ends such that the flow pathway of fluid in the lengthwise direction is forced to follow a curved profile. The inventors have identified that such a curved flow passageway within each module contributes to inducing Dean vortices within the flowing fluid. This fluid flow pattern offers significant advantages over conventional straight tubular arrangements. The characteristic of this flow pattern is a secondary flow whereby vortices perpendicular to the forward flow of the fluid mixture in the tube appear. Two counter-rotating vortices are formed due to centrifugal forces acting on the fluid passing through such a curved passage disrupting the characteristic parabolic profile of the laminar flow found in conventional straight passages at low Reynolds numbers. These vortices create mixing on the perpendicular plane relative to the direction of the fluid flow ensuring highly improved heat and mass transfer, even at lower Reynolds numbers. This is often beneficial for viscous fluid mixtures where heat transfer can be significant. In particular, the present reactor via the lengthwise curved passageway is configured to provide a velocity of fluid that is approximately uniform across any cross-section of passageway extending generally perpendicular to a length of the passageway. In particular, the present reactor and method provides a fluid flow passageway configuration adapted to create and maintain fluid flow having plug flow characteristics within all or a majority of such passageways.

According to a first aspect of the present invention there is provided a modular flow reactor comprising a plurality of modules connectable together, each module comprising a body having at least one fluid flow passageway having an inlet and an outlet end connectable to the inlet and/or outlet ends of adjacent modules when the modules are aligned on a common longitudinal axis and connected together; wherein the at least one passageway comprises a length between the inlet and outlet ends that extends in a plane generally perpendicular to the longitudinal axis; and wherein at least a majority of the length of the passageway is curved continuously in said plane.

Optionally, the body of each module may comprise a generally plate-like shape profile. Optionally, the body of the modules may comprise a first face and a second face orientated generally perpendicular to the longitudinal axis and a perimeter face extending between the first and second faces. Optionally, in a plane of the flat disc-like modules, each module may comprise a circular, continuously curved, or polygonal, e.g., rectangular, hexagonal, octagonal etc., shape profile as defined by a perimeter of each disc-like module.

Optionally, the at least one passageway comprises a channel recessed into at least one of the first and second faces. Optionally, the inlet and outlet ends comprise respective sections of the passageway that are aligned generally parallel to the longitudinal axis. Such inlet and outlet ends may comprises regions of the passageway aligned perpendicular to the main length of the passageway that extends in the circumferential direction around the longitudinal axis.

The flow reactor may further comprise a plurality of sealing members positionable between each of the modules to form a fluid tight seal along the length of the passageway of each module and/or at the inlet and outlet ends. Optionally, the sealing members comprise O-rings and/or gaskets.

Optionally, in the plane perpendicular to the lengthwise (and the fluid flow) direction at each passageway (i.e., a plane aligned with the longitudinal axis), each passageway may be generally curved, circular, part-circular, oval, U-shaped, polygonal, rectangular or a combination of such shape profiles to extend around the longitudinal axis.

Optionally, in the lengthwise direction of each passageway, each passageway may be generally curved continuously, circular or part-circular to extend in the circumferential around the longitudinal axis.

Optionally, each module comprises a plurality of passageways each having a respective length extending around the longitudinal axis to form a set of generally concentric circular passageways, each of the passageways having the respective inlet and outlet end such that a fluid is capable of flowing independently within each of the respective passageways of the set within each of the modules. Optionally, the at least one passageway of each module may comprise a spiral shape profile in said plane.

Optionally, at least some of the modules comprise any one or a combination of the following materials: steel; stainless steel; a polymer; a glass; a ceramic.

Optionally, at least some of the modules may comprise a surface coating provided at the passageway. Optionally, the coating at the passageways may comprise any one or a combination of the following set of: a glass material; a chemically inert material; a catalyst material; a reactant material; a reagent material. Optionally, at least one of the modules may comprise at least one port extending radially inward from a perimeter surface of the module and connected at or towards an inner end with a portion of the passageway.

The reactor may further comprise a plurality of connection conduits coupled to the inlet and outlet ends of respective modules positioned at the axial ends of the reactor.

The reactor may further comprise at least one brace member extending in a direction of the longitudinal axis and coupled to at least some of the modules to retain the modules as an assembly to form the reactor.

Optionally, at least some of the modules may comprise a support material positioned at the passageway to be contacted by fluid flowing through the reactor. Optionally, the support material comprises any one or a combination of the following set of: glass beads; silica beads; nanoparticles; a permeable matrix material.

Optionally, at least some of the modules may comprise a membrane positioned at the passageway and/or the inlet and outlet ends to be contacted by a fluid flowing through the reactor.

Optionally, a width of each of the modules in a direction perpendicular to the longitudinal axis may be greater than a thickness of each of the modules extending in a direction with the longitudinal axis.

Optionally, the at least one passageway of each module may comprise a single continuous curve in the lengthwise direction of the passageway between the inlet and outlet ends.

Optionally, the modules may be coupled face-to-face with the respective channels facing one another to define fluid flow channels defined by the respective channels/grooves formed in each face of each plate-like modules. Optionally, the modules may be positioned with their channelled face positioned against a substantially planar, non- channelled face of a neighbouring adjacent plate. Optionally, the channelled face of a first module may be positioned opposed to a planar non-channelled face of a‘ spacer’ plate with a second module positioned at the opposite non-channelled face of the spacer plate, with the spacer plate positioned between the respective channelled modules.

Optionally, the reactor may be configured for the dual through flow of a reactant fluid and a temperature regulating fluid so as to define two separate fluid networks, each fluid network for the respective reactant fluid and the temperature regulating fluid comprising respective inlets and outlets connected to respective fluid networks optionally including a respective reservoir and associated pumps and valves. Optionally, the reactant fluid may be configured to flow through each module via selected annular channels with separate radially inner and radially outer channels transmitting a temperature control. Internally mounted seals and O rings provide respective fluid separation/isolation of the

independently controlled fluid flow networks. Optionally, the reactor may comprise multiple temperature regulating fluid networks input and output at the reactor at different axial positions with the option of regulating the temperature to provide different temperature zones axially along the length of the modular reactor. Each fluid network may comprise respective sensors including flow rate sensors, temperature sensors and chemical sensors to identify a status of the reactant fluid.

Optionally, the at least one passageway may be divided into a first network for the fluid flow of a reactant fluid and a second network isolated from fluid communication with the first network for the fluid flow of a temperature regulation fluid. The temperature regulation fluid flowing through the reactor is configured to regulate the temperature of the reactant fluid according to a desired and/or predetermined temperature range.

Optionally, the each module may comprise at least one passageway forming part of the reactant fluid network. Optionally, each module may comprise at least one passageway forming part of the temperature regulation fluid network. Optionally, within each module, the temperature regulation fluid flows concentrically relative to the flow of the reactant fluid and the central axis of the reactor. According to a second aspect of the present invention there is provided a method of directing a flow of a fluid through a modular flow reactor comprising: providing an assembly formed from a plurality of modules connected in fluid communication, each module comprising a body having at least one fluid flow passageway having an inlet and an outlet end connectable to the inlet and/or outlet ends of adjacent modules when the modules are aligned on a common longitudinal axis and connected together, the at least one passageway comprising a length between the inlet and outlet ends that extends in a plane generally perpendicular to the longitudinal axis wherein at least a majority of the length of the passageway is curved in said plane; and directing a fluid to flow through the passageways of the modules.

Optionally, the method may further comprise the step of directing the fluid flow through the passageways to achieve a plug-flow fluid flow characteristic. Optionally, the method may further comprise the step of directing the fluid flow through the passageways to achieve a Dean vortices flow characteristic in a cross-sectional plane of the passageway, where the Dean vortices are defined as counter-rotating vortices extending in a cross- sectional plane of the passageway.

Optionally, the method may comprise directing a reactant fluid through a reactant fluid network defined, in part, by a first portion of the at least one fluid flow passageway and directing a temperature regulation fluid through a temperature regulation fluid network defined, in part, by a second portion of the at least one fluid flow passageway isolated from fluid communication with the first portion. Such an arrangement is advantageous to control the temperature of the reactant fluid and the rate of reaction therein.

Optionally, the reactant fluid network extends through each of the modules. Optionally, the temperature regulation network extends through each of the modules.

Optionally, the method may comprise directing a temperature regulation fluid through at least some of the modules via a series of fluid flow conduits formed within at least some of the modules, the conduits being isolated from fluid communication with the fluid flowing within the at least one passageway. Brief description of drawings

A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 is a schematic illustration of a modular flow reactor forming part of a fluid flow network according to a specific implementation of the present invention;

Figure 2 is a further schematic illustration of the modular reactor of figure 1 mounted within a brace assembly according to a specific implementation of the present invention;

Figure 3A is a plan view of one of the plate-like modules of the reactor of figure 2 according to a first embodiment;

Figure 3B is a perspective view of the module of figure 3 A;

Figure 3C is a cross sectional view through A-A of the module of figure 3B;

Figure 4 is a cross sectional exploded view of a set of modules of figures 3A to 3C illustrating the internal fluid flow direction;

Figure 5 A is a plan view of a module of the reactor of figure 2 according to a further embodiment of the present invention;

Figure 5B is a perspective view of the module of figure 5A;

Figure 5C is a cross sectional view through the module of figure 5B;

Figure 6 is an exploded cross sectional view of a plurality of the modules of figures 5A to 5C illustrating the fluid flow pathway through the modules; Figure 7 is a cross sectional view through a portion of one of the modules of figure 6;

Figure 8A is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 8B is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 9A is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 9B is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 10A is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 1 OB is a cross sectional view of two adjacent modules positioned face-to-face according to a further embodiment;

Figure 11 is a perspective view of a modular reactor formed from a plurality of the modules of figure 10A connected face-to-face and defining internal fluid flow passageways having circular cross sectional shape profiles;

Figure 12 is graph of reactor response via tracer concentration at a reactor outlet at different fluid flow rates; and

Figure 13 is a graph of normalised residence time within a reactor according to different fluid flow rates. Detailed description of preferred embodiment of the invention

Referring to figures 1 and 2, a modular flow reactor 10 comprises a plurality of individual plate-like modules 11 connectable face-to-face to form a modular assembly. Each module 1 1 , as detailed below, comprises an internal fluid flow passageway to allow the through- flow of a fluid between modules 1 1 from an inlet port 13 to an outlet port 14 provided respectively at each of the end modules 1 la, 1 lb. A sealing member, in the form of a gasket 12 is positioned between each module 11 so as to provide a fluid tight seal about and between the passageways. According to specific implementations, gasket 12 may be formed by one or a plurality of O-rings or similar deformable sealing elements interposed axially between neighbouring adjacent modules 1 1 and configured to seal the internally flowing fluid.

As illustrated schematically in figure 1, reactor 10 is suitable for fluid coupling to a first reactant vessel 15 and a second reactant vessel 16 via network conduits 22 provided in fluid communication with the inlet port 13. Suitable valves or gates 50 are provided at conduits 22 so as to control delivery of the reactants from vessels 15, 16 into the reactor 10. Similarly, a collection vessel 17 may be coupled to the outlet port 14 via a network conduit 23 optionally involving one or more fluid flow delivery valves or gates 50. The assembly of figures 1 and 2 may further comprise fluid pumps and other suitable auxiliary apparatus (not shown) as will be familiar to those skilled in the art. The present apparatus is further compatible for connection and operation with a plurality of different sensors including temperature, flow velocity, pressure and photo-sensors positionable externally and/or internally at the reactor 10 (within or at the modules 11) and in particular at the internal fluid passageways.

Referring to figure 2, the plurality of individual modules 1 1 are assembled together in face- to-face contact so as to form a unitary body via a plurality of brace elements 18, 19, 20, 21. In particular, a plurality of elongate adjustable rods 21 extend longitudinally between a pair of end brace plates 18 mounted externally with respect to the assembly of modules 11. A plurality of elongate rods 19 extend through each module 1 1 between brace plates 18 with the modular reactor 10 effectively sandwiched axially between brace plates 18 and maintained in position via brace elements 21, 19. A plurality of bolts, washers and fixings (illustrated schematically by reference 20) adjustably secure the reactor 10 within the bracing assembly 18, 19, 20, 21 so as to clamp the modules 1 1 together axially in face-to- face arrangement to form the modular stack. According to the specific implementation, each module 11 is formed as a disk-like element, with the modules 1 1 assembled together and centred on a central longitudinal axis 28 (extending through the reactor 10). A fluid tight seal is created and maintained via sealing members 12 that are compressed axially (in the direction of longitudinal axis 28) via brace assembly 18-21.

Referring to figures 3 A and 3C, each module 11 having a plate-like configuration comprises a first face 30 and an opposite second face 31, with each face 30, 31 aligned perpendicular to axis 28. A fluid flow passageway indicated generally by reference 25 is recessed into face 30 to form a series of channels. According to the specific embodiment of figures 3A to 4, passageway 25 is formed as a set of part-circular passageways each having a respective inlet end 26 and outlet end 27. Between each end 26, 27, each passageway 25 is continuously curved in the plane perpendicular to axis 28 and is centred on axis 28. Accordingly, each module 11 comprises a plurality of concentric passageways 25 that includes a radially outermost passageway 25a, a plurality of intermediate passageways 25c and a radially innermost passageway 25b (positioned radially closest to axis 28). Each module 1 1 comprises a radially outward facing perimeter face 24 that extends in an axial direction between faces 30, 31, with surface 24 being generally circular in the plane perpendicular to axis 28. A plurality of circular grooves 32 are provided each lengthwise side of passageways 25 to mount respective O-rings (not shown in figures 3A to 3C but illustrated schematically in figure 4) at second face 31 to provide the fluid tight seal when the modules 1 1 are assembled together to form part of the reactor 10. Each O- ring comprises a different diameter so as to be positioned and to seat radially between the passageways 25a, 25b and 25c and to be partially recessed relative to face 30.

Accordingly, a fluid tight seal is provided along the length of each passageway 25a, 25b, 25c and at each respective inlet and outlet ends 26, 27. Each module 1 1 further comprises a plurality of axially extending bores 29 to receive brace elements 19 as illustrated in figure 2. Each passageway 25a, 25b, 25c is defined by an inward facing passageway wall including a pair of opposed wall surfaces 36a, 36b and a trough face 36c that together define each respective passageway 25. According to the embodiment of figures 3 A to 4, each passageway 25 comprises a rectangular cross-sectional shaped profile in the cross- section A-A perpendicular to the direction of fluid flow indicated by flow direction arrows 35.

Referring to figure 4 and according to the concentric-circular passageway embodiment of figures 3 A to 4, the fluid flow through the reactor 10 involves fluid flow within

passageway 25a in the circumferential direction around axis 28 (after the fluid has entered reactor 10 via passageway inlet end 26). The fluid flow then continues into the

corresponding passageway 25 of the adjacent neighbouring module 1 1 until the fluid enters end module 1 lb. Tubing 33 is coupled to passageway outlet end 27 and the respective passageway inlet end 26 of end module 1 lb so as to return the fluid flow into the radially inner passageway 25c where it flows in the opposite counter-flow direction following the circular pathway (around axis 28) between the respective inlet and outlet ends 26, 27. Accordingly, the fluid is returned from module 1 lb to module 1 la where it is diverted via corresponding tubing 33 into the next radially inner passageway 25c before returning in the axial direction. As will be appreciated, the fluid flow continues through successive radially inner passageways until it flows around radially innermost passageway 25c within each module 11 to then flow out of the reactor 10 to a suitable collection vessel 17

(referring to figure 1).

Figures 5A to 5C illustrate a further embodiment in which passageway 25 is formed as a spiral between respective inlet and outlet ends 26, 27. Most of the features and general function of the embodiment of figures 3A to 4 are common to the further embodiment of figures 5A to 5C. As with the fist embodiment, and as illustrated in figure 5A, passageway 25 is continuously curved between ends 26, 27. Additionally, passageway 25 comprises a rectangular cross-sectional shaped profile in the cross-section A-A perpendicular to the direction of fluid flow indicated by flow direction arrows 35. Referring to figure 6, fluid flows in a circular direction following a continuously curved flow path from a radially outer position of inlet end 26 to the radially innermost outlet end 27 where it transfers to the neighbouring adjacent module 1 1 of the reactor 10. The fluid in this second or neighbouring module 1 1 then flows in the counter-flow direction from the radially innermost end to a radially outermost end (corresponding to ends 27, 26 of figure 5A).

The fluid is then transferred to the next neighbouring module 11 via the radially outermost end (corresponding to end 26 of figure 5A). Accordingly, the fluid flow through each module is sequentially clockwise and counter-clockwise between end modules 1 1a, l ib between reactor inlet and outlet ports 13, 14. As with the embodiment of figures 3 A to 4, a plurality of sealing members 34 are positioned between each neighbouring module 1 1 so as to form a fluid tight seal about passageways 25 both along the length of passageways 25 and at the respective inlet and outlet ends 26, 27. As illustrated in figure 5B, each passageway 25 of each module 11 is defined by a pair of opposed side wall faces 36a, 36b and a trough face 36c. Unlike the embodiment of figures 3A to 4, the fluid flows completely around the spiral passageway 25 of each plate-like module 1 1 between ends 26, 27 before transferring to the next neighbouring module 1 1. Figure 6 represents a variation of the passageway configuration of figures 5 A to 5C in that trough surface 36C is semicircular such that the internal facing surfaces that defines passageway 25 comprises a U- shape profile in the cross-section perpendicular to the flow direction as illustrated by flow direction arrows 35 (referring to figure 5A).

Referring to figure 7, both embodiments of figures 3A to 6 comprise at least some modules 1 1 having an injection port to enable the introduction of a fluid, sensing probe or other fluid or component into passageway 25 via perimeter face 24. In particular, the injection port comprises a conduit 37 (in the form of a bore) extending radially from perimeter face

24 and into the body of module 1 1 so as to interface at a radially inner end with

passageway 25. Accordingly, an elongate probe 38 (or alternatively a fluid) is capable of being inserted (or delivered) into conduit 37 such that a distal end 40 of probe 38 is positionable within passageway 25. Such an arrangement enables the introduction of additional reactant fluids, catalyst products, sensing elements, injection tubes and the like at passageway 25 from an external region of reactor 10. According to further specific embodiments and as illustrated by way of example referring to figure 7, each passageway

25 may comprise a surface coating 41 provided at any one or a combination of faces 36a, 36b, 36c. Coating 41 may comprise a chemically inert material such as glass, a catalyst, a reactant or a reagent for contact by the fluid (flowing within passageway 25). According to further embodiments, each module 11 may be provided with a membrane or a plurality of membranes aligned lengthwise to partition each passageway 25 in the lengthwise direction or one or plurality of membranes aligned perpendicular to the fluid flow direction. According to yet further embodiments, a support material may be positioned within passageway 25 and may comprise beads such as glass or silica beads, nanoparticles or other fluid contacting bodies configured to provide reactive surfaces in contact with the fluid.

As illustrated in figures 8A to 9B, each modules 1 1 may be configured for positioning face-to-face via opposed faces 30 and/or 31. That is, each axially neighbouring and adjacent module 11 may be positioned with faces 30 being opposed to one another so as to enlarge the cross-sectional surface area of passageway 25 to be effectively double that of the embodiments illustrated with reference to figures 4 and 6. Such further embodiments similarly comprise sealing members 34 in the form of a plurality of O-rings or gaskets mounted at least partially within respective grooves 32. Figures 8A and 8B correspond to the concentric circles embodiment of figures 3A to 4 with the modules 1 1 positioned faced -to-face by their respective faces 30. The embodiment of figure 8 A differs by comprising passageways 25 having a semi-circular cross sectional shape profile such that when assembled as illustrated in figure 8B each passageway comprises a generally circular cross sectional profile in a plane perpendicular to the fluid flow direction indicated by flow arrows 35 (of figure 3 A). Similarly, figures 9 A and 9B correspond to the spiral embodiment of figures 5A to 5C. Figure 9B being similar to figure 8B corresponds to the spiral embodiment in which the passageway 25 of each module 11 comprises a semicircular cross sectional shape profile such that when modules 1 1 are placed in contact with one another via their respective faces 30, the passageway 25 comprises a circular cross sectional profile perpendicular to the flow direction indicated by flow direction arrows 35 (of figure 5 A).

Figures 10A and 10B illustrates respective further embodiments being extensions of the embodiments of figures 9B and 9A respectively. According to the further embodiments of figures 9A and 10B, each face 30, 31 is provided with a recessed channel to define respectively one half of the passageways 25 according to the spiral configuration of the embodiment of figures 5 A to 6. Each of the further embodiments of figures 10A and 10B also comprise the grooves 32 positioned radially adjacent each of the passageways 25 so as to provide the fluid tight seal at each respective passageway 25. Figure 1 1 illustrates reactor 10 formed from the assembled modules 1 1 of figure 10A connected with each face 30 positioned opposed to and in touching contact with the face 31 of a neighbouring and adjacent module 11. According to the embodiment of figure 10A each passageway 25 is formed by a channel recessed into face 30 and 31 having a semi-circular cross sectional shape profile (in a plane perpendicular to the flow direction, indicated by flow direction arrows 35 of figure 5A) such that each passageway 25, as illustrated in figure 11, comprises a generally circular shape profile in the plane perpendicular to the fluid flow. Similarly and according to the embodiment of figure 10B, each passageway 25 within the assembled reactor 10 comprises a generally rectangular shape profile in the plane perpendicular to the fluid flow. As illustrated, the assembly 10 comprises a generally cylindrical configuration having a generally cylindrical external face 24 centred on longitudinal axis 28 and a pair of opposed end faces defined by each respective face 30, 31 of each axial end module 1 IB, 11 A respectively.

As will be appreciated, the further embodiments of figures 9A to 1 1 may be implemented with the concentric circular arrangement of passageways 25 according to the embodiment of figures 3 A to 4 or the spiral configuration of the embodiment of figures 5 A to 6 having the respective sealing O-rings or gaskets appropriate to the passageway arrangement in order to provide the fluid tight seal internally within the assembly 10.

According to further implementation, regions of passageways 25 (according to all the embodiments described herein) may comprise obstructions formed by fins, projections, ribs, ridges, grooves, scoring, gaskets, flanges and the like being provided within so as to create turbulence to the fluid flow and facilitate mixing. In particular and preferably, such static mixes may be provided within regions of passageway 25 in the form of square, circular or diamond shaped obstructions, projecting inwardly from one or more of the faces 36a, 36b, 36c that define each respective passageway 25.

As will be appreciated, the modules 11 as described herein may be manufactured conveniently via a variety of different manufacturing methods including machining, injection moulding, 3D printing, casting, electron discharge machining, electrochemical machining etc., being dependent upon the material of the modules 1 1 that may comprise for example steel, stainless steel, polymer, ceramic, glass or a combination of such materials including material configurations having surface coatings provided at regions of channels 25.

The inventors have identified that providing a fluid flow passageway 25 that is generally continuously curved about axis 28 is effective to establish and maintain specific fluid flow characteristics throughout the internal reactor passageway 25. In particular, the lengthwise curved passageways 25 and in particular the lengthwise longitudinal curvature of face 36a imposes centrifugal force and centripetal force on an otherwise laminar flow. These forces disrupt the otherwise parabolic profile of the laminar flow that would in turn create a differential fluid flow velocity profile (typically with a maximum velocity positioned at the centre of the passageway 25 and decreasing towards faces 36a, 36c). However, lengthwise curved face 36a (and faces 36b, 36c) provides a desired pressure gradient within the fluid (between the faces 36a, 36b) which in turn gives rise to hydrodynamic instability and development of secondary flow characteristics within each passageway 25. Such secondary flow characteristics manifest as counter-rotating vortices referred to herein as Dean vortices (alternatively referred to as Dean flow). Accordingly, as a consequence of the desired flow characteristics within passageways 25, a desired fluid velocity profile is created in the cross-section of the longitudinal flow direction (arrow 35). The fluid with such a profile comprises a substantially uniform velocity within the cross-section and is referred to herein as the establishment of a plug flow characteristic. Accordingly, the present modules 11 and reactor 10 are configured to minimise and preferably eliminate back-mixing in the reverse flow direction through the reactor. Accordingly, the present invention is adapted to eliminate backward mixing or upstream perturbations so as to fully control the mixing and flow characteristics through the reactor 10 as desired. Accordingly, when reactor 10 is implemented for processing chemical reactions, the occurrence of undesirable side reactions, (as a result of otherwise differential fluid flow velocities through the passageway 25), are minimised and preferably eliminated via creation of Dean vortices and the plug flow characteristic. Performance Results

The performance mixing of a fully assembled reactor based on the type shown in figures 1 and 2 comprising a plurality of reaction modules 1 1 having a spiral configuration of fluid flow passageway 25 according to figures 5A to C, was investigated using a standard Residence Time Distribution (RTD) study for non-ideal flow reactors as described in LEVENSPIEL O., 1999, Chemical Reaction Engineering, Third Edition, John Wiley and Sons Inc, ISBN 0-471-25424-X. During the RTD study, a sort impulse of a tracer

(coloured material) was injected into an otherwise colourless fluid flow inside the prototype reactor at the inlet.

The RTD response of the reactor shows its mixing efficiency. This is determined by measuring the tracer concentration over time at the outlet. The tracer concentration was measured using a standard UV-Vis spectrophotometer attached at the outlet of the reactor. The tracer concentration is proportional to the absorbance intensity of the solution at the outlet. A narrow RTD profile with a short tail is preferable for plug flow reactors. A long tail means that there is back-mixing which is generally undesirable. Mixing efficiency with the present invention accrues due to the formation of Dean Vortices within the flowing fluid and their formation depends on the fluid mixture velocity within the reactor.

A series of tests were performed by injecting the same amount of tracer fluid into the colourless fluid at the inlet. The colourless fluid was allowed to enter continuously into the reactor at the inlet, while a pulse of 1 mL of tracer was injected momentarily at the same inlet via a T-junction. Both fluids were injected into the reactor using computer controlled high precision syringe pumps. Controller code for the pumps was purposely built in LabView software. Specifically three tests were conducted by varying the overall fluid mixture velocity, or net flow as shown in Table 1. Net Flow RTD Tracer exit

mL/sec Skewness duration at the

outlet

sec

450 0.064 ΪT2

310 0.043 13.6

240 0.035 21.6

Table 1 Residence Time Distributions within a reactor versus net flow rate

Figure 12 is a graph of the reactor response by means of the tracer concentration at the outlet over time. Figure 12 confirms that with decreasing flow rates the tracer not only takes longer to exit the reactor as expected but also higher dispersion is observed. This is expected as the secondary Dean flow regime which enhances mixing, is a function of the mixture flow rate. Figure 13 shows the Residence Time Distribution profiles for each of the three net flow rates. In these tests based on the reactor of figure 1, 2 and 5A to 5C, one can observe a slight positive skewness which means there is a slight tail on the right hand side especially at the higher flow rates. This means that at higher flow rates, there is less back mixing and narrower distribution compared to the lower flow rates. Both Figures 12 and 13 confirm that it is possible to tune the performance of the reactor to fit the requirements of the process as a function of mixture Reynolds number, flow regime and output flow rates.