WO2007065211A1

WO2007065211A1 - Modular chemical reactor

Info

Publication number: WO2007065211A1
Application number: PCT/AU2006/001850
Authority: WO
Inventors: David West Mckenzie; Robert Charles Carnell; Michael Everton
Original assignee: Acqua International Group Inc
Priority date: 2005-12-06
Filing date: 2006-12-06
Publication date: 2007-06-14
Also published as: AR058280A1; TW200738330A

Abstract

A compact reactor and a method of using the compact reactor is described in which the compact reactor is assembled in the form of modules of individual reactor elements interconnected together. The reactor elements are a selection of straight reactor elements and curved reactor elements. The reactor elements can be a single type or can be multiple pipes. The reactor elements are connected in such a manner so that part of the reactor bends or folds back upon itself so that the reactor has a small footprint and/or occupies a small space. The advantage of the compact reactor is that long residence times in the reactor can be attained using lengthy reactors but without occupying a large space or requiring structural reinforcement to support long linear lengths of reactors. The compact reactor is cheaper to manufacture and occupies less space than conventional linear reactors. The reactor is used particularly to transesterify oils, fats, greases and similar products to produce bio-diesel or bio-diesel fuel components.

Description

MODULAR CHEMICAL REACTOR

Field of the Invention The present invention relates to chemical reactors and to methods of assembling and using chemical reactors.

In one aspect the present invention relates to modular reactors formed from an assembly of a multitude of

individual reactor elements connected together to form ^"a variety of different forms and/or configurations of reactors including reactors made from reactor elements of variable length and/or sizes and/or shapes. In another aspect the present invention relates to a compact modular reactor having a multitude of modules of different reactor elements arranged in a variety of different preselected arrays to form the modular reactor, particularly compact modular reactors, having a relatively small footprint or occupying a relatively small space, particularly when compared to the size and space occupied by more conventional elongate reactors made from straight tubes . Although the present invention will be described with particular reference to a selection of one or more forms of the compact variable length modular reactor it is to be noted that the scope of the present invention is not restricted to the described embodiment or embodiments but rather the scope of the present invention is more

extensive so as to include other forms and arrangements of the reactor elements, other combinations of the reactor elements, other arrays of reactor elements, modules or the like, other configurations of the reactor, other methods of using the reactor and to other uses of the reactor elements, modules or the like. Background of the Invention

Chemical reactors are used to perform a wide variety of chemical reactions in which a diverse range of chemical compounds are formed. The nature of the chemical compound formed determines the type, size and style of the reactor. The length of the chemical reactor required for a

particular chemical reaction is determined by many factors including the residence time of the various reactants of a particular chemical reaction necessary to enable the reactants to react to form sufficient yield of the product for the chemical reaction to be commercially viable.

Often reactors are required to be of great length for there to be acceptable residence time within the reactor so that there can be satisfactory conversion of reactants to products to form commercial quantities of the required product or products. One way of providing sufficiently long residence time is to provide reactors of long

straight pipes. These are generally arranged horizontally or vertically. If the long pipes are arranged

horizontally the reactor has a large footprint requiring excessive space which is often neither readily available nor practical to provide such room for the installation of chemical plants since the availability of space in

chemical engineering plants is often at a premium. If the reactor tubes are arranged vertically they often extend to an excessive height making the chemical plant or

installation either unstable or requiring costly

reinforcement and additional supports to brace or stabilise the installation. Often it is not possible to reduce the length of the reactor owing to the length of the residence time of the chemicals in the reactor

necessary for substantial reaction and conversion of the reactants into products for the process to be commercially attractive. Thus, there is a need for a long or lengthy reactor which has a small footprint or occupies a small space. Thus, one of the aims of the present invention is the need to provide a more compact reactor arrangement having a small footprint and/or occupying a small space in an installation or chemical plant when compared to

conventional reactors whilst having a sufficient length to allow the chemical reaction to take place in the reactor to proceed to such an extent so as to make use of the reactor economically viable.

Another aim of the present invention is to provide a compact modular reactor in which one or more

transesterification 'reactions can take place, particularly transesterification of fatty acids to produce fatty acid alkyl esters from which bio-diesel can be obtained, which reactors are space efficient by occupying a small

footprint or a small space.

Summary of the Invention

According to one aspect of the present invention there is provided a compact chemical reactor comprising at least one first reactor element of a first length and of a first configuration having a first end, and at least one second reactor element of a second length and of a second - A - configuration having a first end, wherein said first end of the first element is connectable to the first end of the second element to form the reactor wherein the reactor has a different length and configuration to either one of the first or second reactor elements and wherein the configuration of the reactor is such that at least a part of one of the elements forming the reactor is arranged in spatial relationship with at least a part of another of the reactor elements forming the reactor thereby forming the compact reactor.

According to another aspect of the present invention there is provided a method of varying the length and

configuration of a compact modular chemical reactor comprising the steps of connecting a first end of a first reactor element having a first length and a first

configuration to a first end of a second reactor element having a second length and a second configuration, thereby forming the compact modular reactor having a preselected length and configuration which is different to the length and configuration of either one of the first or second elements wherein at least one of the reactor elements is in a spatial relationship with at least a part of another reactor element thereby forming the substantially compact reactor.

According to another aspect of the present invention there is provided a compact chemical reactor comprising a multitude of first reactor elements having a first length and a first configuration and a multitude of second reactor elements having a second length and a second configuration, said first and second reactor elements being joined together to form a predetermined array of first and second elements to form the reactor wherein at least a part of some of the multitude of first reactor elements are arranged in spatial relationship with at least a part of others of the first reactor elements thereby forming a compact reactor.

According to another aspect of the present invention there is provided a compact modular reactor for carrying out a transesterification reaction to produce fatty acid alkyl esters for use in producing bio-diesel, said compact reactor comprising at least one first reactor .element of a first length and of a first configuration having a first end, and at least one second reactor element of a second length and of a second configuration having a first end, wherein said first end of the first element is connected to the first end of the second element to form the reactor wherein the reactor has a different length and

configuration to either one of the first or second reactor elements and wherein said configuration of the reactor has at least a part of one of the elements which is arranged in spatial relationship with at least a part of another of the reactor elements thereby forming the compact reactor.

According to a still further aspect of the present

invention there is provided a method of producing bio- diesel comprising introducing one or more reactants to a compact modular reactor, allowing the reactants to react in the reactor to form at least partially bio-diesel or a bio-diesel precursor in pure and/or contaminated form wherein the reactor comprises at least one first reactor element of a first length and of a first configuration having a first end, and at least one second reactor element of a second length and of a second configuration having a first end, wherein said first end of the first element is connected to the first end of the second element to form the reactor wherein the reactor has a different length and configuration to either one of the first or second reactor elements and wherein said

configuration of the reactor has at least a part of one of the elements which is arranged in spatial relationship with at least a part of another of the reactor elements thereby forming a substantially compact reactor.

Brief Description of the Invention

Typically, one form of the reactor of the present

invention is a reactor of variable length that includes a multitude of straight reactor tubes or pipes connected with a plurality of curved tubes or pipes arranged in such a manner to form a convoluted or sigmoidal compact reactor having a reactor length greater than at least one

dimension of the footprint of the reactor by at least some reactor elements being folded over one another or

superposed over one another or the like, such as for example in a serpentine or sinusoidal configuration.

Typically, the spatial relationship between the two reactor elements includes superposable, aligned, adjacent, contiguous, side by side, one on top of the other or any other spaced relationship between the two reactor

elements . It is to be noted that the use of the term superposed or one above the other or similar expressions is not meant to be limiting to one element being placed directly above the other element or being arranged exactly in alignment with one above the other but rather this word is meant to be interpreted liberally to include that the two elements are in proximity to or in at least partially spaced apart relationship with each other in some spatial arrangement which can be vertical, horizontal or oblique and/or be partially or entirely in alignment with each other or in partial or total overlapping relationship or the like.

The term superposable is merely meant to imply that there is a close spatial relationship between the reactor" elements such as for example, an overlapping relationship, one element overlying the other element, or the two elements being in side by side relationship or one element being located at different levels so that one is located above the other element, or the two elements comprising a ¹S' shape, ¹U' shape or any other shape in any arrangement or order that allows a compact reactor to be assembled from the reactor elements which has a small footprint or occupies a small space. Typically, the configuration of the reactor is convolute, winding, tortuous, sinusoidal, coiled, helical, spiral, cork-screw, twisting, turning, volute, serpentine

undulating, wave-like, tortile, vermiform, sigmoidal, complex curved, compound curved, labyrinth-like, circular, ring-like, elliptical, ovoid, annular, or the like. In one embodiment, there is a single arrangement of two or more elements whereas in other embodiments, there is two, three or more separate groups of elements connected together to form respective entwined pathways such as for example in the shape or form of a double helix, a double spiral, a double coil, a triple coil or other entwined shape of two or more groups of reactor elements. Typically, the configuration of the first element can be the same or different to the configuration of the second element. More typically, the configuration of the first element is in the same or different orientation,

curvature, alignment, rotation, turning or other when compared to the configuration of the second element. Even more typically, the first element extends in the same or a different direction to the second element, such as in an opposite direction, a complementary direction or in a direction having any other relationship with the direction of the elements to form a compact reactor, such as for example, a reactor having elements folded back on one another so as to reduce the footprint of the reactor. Typically, the first or second reactor element is an elongate element, typically a straight element, more typically a cylindrical element being a hollow straight walled tube, typically a tube having a constant diameter throughout its length, and more typically a cylindrical tube having one end or both ends open. More typically, the reactor element can be a single tube element, a double pipe element or a multiple pipe element in which the element is provided with two or more internal reactor pipes in fluid communication with each other. Even more typically the reactor element is a multiple arrangement in which the pipes are joined to a common distributor or manifold at one or both ends or each pipe has its own dedicated end of the tube which is connected in fluid communication to another one of a second set of multiple pipes forming the second reactor element. Even more typically, each of the tubes or pipes is provided with a flow control device, such as for example, a valve. In the event there are multiple pipes within the one tube, each, or selected multiple pipes is provided with a control valve.

Typically, the cylindrical tube or tubes has a flange, more typically, there is a flange located at or towards one end. More typically, there is a flange located at or towards both ends of the cylindrical tube. Even more typically, the multiple internal pipes are joined to each other so as to be in separate fluid communication or the pipes can be in common fluid communication.

Typically, the first or second reactor element is a curved tube. Typically, a curved hollow tube or similar. More typically, a single, double or multiple pipe reactor element having a plurality of internal pipes which are curved substantially in common with each other so as to be substantially regularly spaced apart from each other over their length. More typically, the curvature of the tube can vary from a about 5° to 270°, typically from about 30° to 210°. Most preferably the curvature of the second reactor elements is about 90°, about 120°, about 180° or the like. Typically, the curved part of a reactor is made from more than a single curved element.

Typically, the first ends of the reactor elements are flanged or provided with flanges or other suitable

connectors or connecting elements allowing the reactor elements to be connected to other reactor elements. More typically, the flanged portions are common to all of the reactor elements being assembled together to form the reactor allowing the reactor elements to be interchangeably interconnected together to form different arrays or arrangements of tubes to form reactors of variable lengths by having variable configurations . More typically, flanges are provided at either end of the reactor element or at some or all of the ends of the reactor element. . In some embodiments, the reactor element may be branched by having three sections interconnected at a common junction. In this embodiment, the branched tube has three ends with each end being provided with a flange. Typically, all the flanges are identical so that the ends can be connected to other reactor elements interchangeably in different arrays of reactor elements.

Typically, the first straight elements and the second curved elements can be connected in any array or

arrangement allowing a more compact footprint or space. More typically, the first reactor elements alternate with the second reactor elements. Alternatively, there can be two or more first elements joined together or two or more second elements joined together. Typically, the reactor elements are alternately arranged or similar or are assembled in any order or sequence including blocks of one type of elements and blocks of other types of elements. More typically, the straight elements are arranged in substantially parallel relationship to each other,

preferably in spaced apart substantially parallel

relationship to each other and more preferably in either side by side parallel relationship or superposed

relationship in which the elements are located one above the other in substantially parallel relationship or in alignment with each other such as being located at

different vertical levels to one another. Typically, the compact size of the reactor is determined by the length of one or more of the elements, typically, the length of the straight element, the curved element or a combination of one or more curved elements and a

straight element. Typically, the compact reactor is formed by reactor tubes being arranged to fold back or bend back on each other or to be in a stacking array one over the other or in a side by side array or a combination of two or more different spatially arranged arrays or the like.

Typically, the reactor is a plug flow reactor. More typically, the reactor is a pressurised plug flow reactor. More typically, the reactor is a continuous reactor or a substantially continuously operated reactor. Typically, the reactor is a turbulent reactor or causes the reactants to mix by turbulence, particularly as the reactants pass through the reactor.

Typically, the reactor is provided with a multitude of pipes, more typically, a multitude of pipes in parallel relationship to one another located internally within the reactor tube. More typically, there are from about 1 to about 100 individual pipes located within one reactor tube. Preferably, there are from about 20 - 60 internal pipes, more preferably 30 to 50 internal pipes, located in any arrangement within the reactor element. Typically, the internal pipes are located within the straight reactor tubes or elements. More typically, the multitude of reactor pipes are located within an outer housing, shroud, cover, casing or similar closure or the multitude of pipes are exposed. Alternatively, the walls of individual pipes of the multitude of pipes are in contact with one another or the pipes are spaced apart from each other.

Typically, the pipes are provided with a manifold or distributor. More typically, several pipes are connected to the one manifold. Even more typically, there is a manifold or distributor located at both ends of the pipes or tubes. Even more typically, the manifolds and/or tubes are located within a pressure vessel or similar.

Typically, the reactor is suitable for transesterification reactions, more typically, transesterification reactions of fatty acid containing materials to form fatty acid alkyl esters, particularly fatty acid methyl esters

(FAME'S), fatty acid ethyl esters, or the like. More typically, the reaction taking place within the reactor is up to about 97% conversion of reactants to products. Even more typically, the fatty acid alkyl esters form the bio- diesel or are treated, such as for example, refined to form bio-diesel, particularly the FAME'S form the bio- diesel .

Typically, the raw material being transesterified in the reactor is an oil or fatty or grease material. More typically, the raw material is a waste material, a used material, unused material, virgin material or the like. More typically, the oil is sunflower oil, rapeseed oil, palm oil, cotton, corn, canola, coconut, soya, tallow or the like

Typically, the reactor is a single reactor or two or more reactors, including groups of reactors arranged in modules including modules having parallel reactors. More typically, the modules are arranged in trains, serially, or the like. More typically, there are many combinations of reactors including reactors having one, two, three, four or moire reactor elements of straight and curved reactor elements joined together. The combination of reactor elements form a reactor, and groups of reactors form a reactor module and groups of modules form a reactor train. More typically, the reactor is provided with a base, base assembly, base framework, support or similar upon which the reactor or reactor elements are located.

More typically, the base structure is modular allowing the base and reactor combination to be assembled or moved as a single unit or module. Alternatively, the one base unit or the like supports multiple reactor elements or

reactors.

Typically, the processing capacities of the reactor are from about 2 million to 10 million litres per month.

Typically, the reactor is able to product 13,900 litre of bio-diesel per hour or 8,300,000 litres of bio-diesel per month.

Typically, the transesterification reaction results in little or no free fatty acid or oil being produced in the reactor. Rather, it is converted to substantially pure fatty acid ester and stored. If an acid

transesterification system is incorporated into the overall process as an option, any remaining free fatty acid will be converted to bio-diesel to provide an overall conversion yield of up to almost 100% or similar.

Description of the Drawings The present invention will now be described by way of non limiting example with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of one form of the compact modular reactor of the present invention with the reactor elements interconnected together in a

generally sigmoidally or ¹S' configuration or shape to form a module of reactors; and

Figure 2 is a schematic perspective view of one embodiment of one reactor element in the form of exposed multiple pipes having individual control valves connected to manifolds located at either end of the pipes.

Detailed Description of the Invention

In Figure 1 there is shown one form of one module forming the compact modular chemical reactor of the present invention generally denoted as 2. It is to be noted that the modular chemical reactor 2 is in the form of a module having four identical reactors, 4a, 4b, 4c, 4d located in parallel side by side relationships to each other. Each reactor is of a generally convolute or serpentine shape and is made up of a number of reactor elements. However, any other convenient shape is possible. Although four side by side reactors 4a, 4b, 4c, 4d are shown, it is to be noted that any number of reactors 4 in any

configuration and of any type can form other arrangement of the module. Further, the numbers of individual modules of the modular reactor 2 can be arranged to form reactor trains having any size, configuration, number of modules, or the like. As the four reactors 4a, 4b, 4c, 4d are substantially identical only one of the reactors 4a will be described in detail for ease of understanding and clarity of

description. Further, it is to be noted that the various reactors within the one module may be the same or

different from one another, or may be arranged in any combination having a small footprint or occupying a small space.

Inlet conduit 10 is provided for admitting reactants. In one form, the reactants are raw materials, typically waste containing animal or vegetable oils or fats, or virgin oil containing material. In this case the reactor is to be used for a transesterification reaction. Inlet conduit 10 for admitting the raw material to reactor 4a is split into two inlet conduits 12, 14, each of which is in fluid communication with its own pressure pump 16. A transfer conduit extends from the outlet of pump 16 to reactor 4a. Reactor 4a will now be described in more detail. Reactors

4b, 4c and 4d are similar and need not be described.

Reactor 4a includes end cap 22 having a centrally located aperture for receiving the end of transfer conduit 18. First reactor element 24 is a cylindrical hollow tube in the form of a single pipe having a flange 26 located at either end. End cap 22 closes the upstream end of tube 24 having flange 26a. If required, a gasket (not shown) is located between flange 26a and end cap 22 to assist in sealing reactor tube 24 against leaks and/or loss of pressure. A second reactor element 28 having a first flange 30a located at the upstream end, and a second flange 30b located at the downstream end is connected to the

downstream end of first reactor element 24 by flange 26b of reactor 24 being connected to flange 30a of reactor tube 28. Reactor element 28 is a generally curved hollow tube formed as a single pipe. The degree of curvature of hollow tube 28 can be any convenient curve such as for example from about 5° to about 270°. However, in the described embodiment reactor tube 28 has a curvature of about 180° so as to fold the reactor back upon itself with flange 30b being located generally above flange 30a.

A third reactor tube 32 having upstream end flange 34a and downstream end flange 34b, is connected to the upstream end of curved reactor tube 28 by downstream end flange 30b being connected to upstream end flange 34a. Reactor tube 32 is a straight cylinder of the same size and same configuration as reactor tube 24 and is a single pipe. Owing to the curvature of reactor 28 reactor tube 32 overlies reactor tube 34 in substantially parallel spaced apart relationship one above the other.

A second curved reactor tube 36 having upstream end flange 38a and downstream end flange 38b is located in place at the end of straight reactor tube 32 so that the upstream end flange 38a is connected to downstream end flange 34b of reactor tube 32 to form a further part of the reactor. The curvature of curved reactor tube 36 is about 180° so that third straight reactor tube 40 can be located above but spaced apart from second straight reactor tube 32 by flange 38b of reactor tube 36 being connected to upstream end flange 42a of reactor tube 40. End cap 44 seals the open end of reactor tube 40 surrounded by flange 42b.

Outlet conduit 46 extends outwardly from end cap 44.

Discharge conduit 48 is provided in outlet conduit 46 for discharging reacted product from reactor 4a. The outlet conduit from reactor 4b is also connected to discharge outlet 48 as reactors 4a, 4b can operate in tandem.

By reactor 4a being composed of alternatively arranged straight reactor tubes 20, 32^", 40 and curved reactor tubes 28, 36 it is possible to have a long length of reactor beginning at end cap 22 and finishing end cap 44 yet occupying a small footprint or space only by parts of the reactor being superposed, bent or folded upon other parts of the reactor into a convoluted or serpentine shape or similar so as to occupy a relatively small space or footprint in a chemical engineering plant or similar.

By judicious selection of straight reactor tubes and curved reactor tubes it is possible to form a reactor of any length yet occupy a small footprint. Although a reactor having three straight tubes and two curved tubes is shown it is to be noted that any number of straight tubes and curved tubes of any configuration interconnected in any combination can be used to provide a compact modular reactor, including a spiral or helical

configuration made from curved tubes only, or a

configuration having vertical straight tubes or the like. Also, it is to be noted that whilst curved reactor tubes

28 subtend an angle of 180°, the curved tubes can be at any suitable or desirable angle depending upon the layout required of the reactor. As an example, two 90° reactor tubes can be arranged in back to back relationships to form a 180° bend in place of a single 180° reactor tube. Four 90° bend tubes can be arranged in back to back relationship to form one turn of a spiral. Additionally, two separate reactor tubes can be entwined about each other in a double coil or helix arrangement . The flanges located at either end of the reactor elements can be at right angles, perpendicular, transverse, inclined or similar so that the reactor elements when joined are not in the same plane but are staggered or helical or the like.

A modified form of the reactor element is illustrated in Figure 2.

In this embodiment, the modified reactor element,

generally denoted as 60 is in the form of a multitude of straight pipes denoted as 62a, 62b, 62c, 62d and so on depending upon the number of individual pipes forming the reactor element 60. Straight reactor element 60 includes a first distributor or manifold 64 located at one end of reactor element 60, such as for example the upstream end for receiving chemical material therethrough from another reactor element (not shown) or from a suitable inlet conduit or similar. A second distributor or manifold 66 is located at the downstream end of reactor element 60 for discharging chemical material from the reactor element 60 to another reactor element (not shown) in fluid

communication with reactor element 60 or to a discharge conduit (also not shown) . A valve 68a, is located along the length of pipe 62a near to distributor 64 for

controlling flow through pipe 62a. Similarly, pipe 62b is provided with valve 68b for controlling flow through pipe 62b and pipes 62c, 62d are provided with valves 68c, 68d, respectively for controlling flow through these pipes. Each pipe 62 is provided with its own valve 68 for

independently controlling flow within each respective pipe to adjust the total flow through this reactor element.

In one embodiment, pipes 62 are exposed with individual pipes located at spaced apart locations as shown in Figure 2, whereas in other embodiments, pipes 62 are enclosed within a suitable covering, housing, casing, shroud or the like (note shown) depending upon requirements.

In a still further embodiment (not shown) , the pipes 62 and manifolds 64, 66 are all located within a pressure vessel or similar.

Advantages of the Invention

Advantages of the present invention include being able to make lengthy reactor tubes to provide almost complete reaction depending upon the nature of the reactants and the degree of conversion required whilst still occupying the small footprint or compact space.

Advantages of the apparatus of the present invention include being able to operate the reactor as a continuous process by utilising plug flow reactors made from chemical resistant and high pressure materials. Capacity of the overall reactor can be increased by adding extra reactor trains without the need to add proportional numbers of extra vessels as the length of the reactor can be increased without significantly increasing the size or space required of the reactor.

The reactor has flexibility in operation since concurrent reactors can be operated in parallel. In the claims which follow and in the preceding

description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A compact chemical reactor characterised in that the reactor comprises at least one first reactor element of a first length and of a first

configuration having a first end, and at least one second reactor element of a second length and of a second configuration having a first end, wherein said first end of the first element is connected to the first end of the second element to form the reactor wherein the reactor has a different length and configuration to either one of the first or second reactor elements and wherein the

configuration of the reactor is such that at least a part of one of the elements forming the reactor is arranged is spatial relationship with at least a part of another of the reactor elements forming the reactor thereby forming the compact reactor.

2. A method of varying the length and/or configuration of a compact modulator chemical reactor

characterised in that the method comprises the steps of connecting a first end of a first reactor element having a first length and a first

configuration to a first end of a second reactor element having a second length and a second configuration, thereby forming the compact modular reactor having a preselected length and

configuration which is different to the length and configuration of either one of the first or second elements in that at least one of the reactor is in at least a spatial relationship with at least a part of another reactor element thereby forming the compact reactor.

3. A compact chemical reactor characterised in that the reactor comprises a multitude of first reactor elements having a first length and a first

configuration and a multitude of second reactor elements having a second length and a second configuration, said first and second reactor elements being joined together to form a

predetermined array of first and second elements so as to form the compact reactor wherein at least a part of some of the multitude of first reactor elements are arranged in spatial relationship at least apart of other of the first reactor elements or part of some of the multitude of second reactor elements thereby forming the compact reactor.

4. A compact modular reactor for carrying out a

transesterification reaction to produce fatty acid alkyl esters for use as or in producing bio-diesel, characterised in that the compact reactor comprises at least one first reactor element of a first length and of a first configuration having a first end and at least on second reactor element of a second length and of a second configuration having a first end wherein said first end of the first reactor element is connected to the first end of the second reactor element to form the compact reactor wherein the reactor has a different length and configuration to either one of the first or second reactor elements and wherein said

configuration of the reactor has at least a part of one of the elements which is arranged in spatial relationship with at least a part of another of the reactor elements thereby forming the compact reactor.

5. A method of producing bio-diesel or a precursor for bio-diesel characterised in that the method comprises introducing one or more reactors to a compact modular reactor, allowing the reactors to react in the reactor for a time sufficient to form at least partially bio-diesel or a bio-diesel precursor in pure and/or contaminated form wherein the reactor comprises at least one first reactor element of a first length and of a first

configuration having a first end, and at least one second reactor element of a second length and of a second configuration having a first end wherein, when the first end of the first element is connected to the first end of the second element, the compact reactor is formed wherein the reactor has a different length and configuration to either one of the first or second reactor elements and wherein the configuration of the reactor has at least a part of one of the elements arranged in spatial relationship with at least a part of another of the reactor elements to form the compact bio-diesel reactor.

6. A method of assembling a compact reactor,

particularly a compact reactor suitable for carrying out a transesterification reaction to produce fatty acid alkyl esters for use in producing bio-diesel characterised in that the method comprises connecting one end of a first reactor element to the end of a second reactor element to form the compact reactor in which the transesterification reaction can take place.

7. A reactor or method according to any preceding

claim characterised in that the spatial

relationship between the first and second reactor elements includes one element being superposable, aligned, adjacent, contiguous, side-by-side, one on top of the other or any other spaced relationship to the second reactor element.

8. A compact reactor or method according to any- preceding claim characterised in that the

configuration of the reactor formed by connecting the individual reactor elements to one another is convolute, winding, tortuous, sinusoidal, coiled, helical, spiral, corkscrew, twisting, turning, volute, serpentine, undulating, wave-like, tortile, vermiform, sigmoidal, complex curved, compound curved, labyrinth-like, circular, ring-like, elliptical, ovoid or annular including combination of two or more of the foregoing.

9. A compact reactor or method according to any

preceding claim characterised in that the reactor is a single arrangement of two or more elements or is an arrangement of two or more separate groups of elements characterised in that the two groups of separate elements are entwined with respect to each other in the form of a double arrangement including a double helix, a double spiral, a double coil, a triple coil, a double signoidal arrangement or serpentine arrangement or the like.

10. A compact reactor or method according to any

preceding claim characterised in that the

configuration of the first reactor element is the same or different to the configuration of the second reactor element.

11. A compact reactor or method according to any

preceding claim characterised in that the reactor element is a straight element, a curved element or a combination of straight portions and curved portions.

12. A compact reactor or method according to any

preceding claim characterised in that the first or second reactor element is a cylindrical element having a hollow straight walled tube of

substantially constant diameter throughout its length.

13. A compact reactor or method according to any

preceding claim characterised in that the reactor element is a pipe, a double pipe, a triple pipe, or multiple pipe in which there are two, three, four or more individual pipes forming the reactor element.

14. A compact reactor or method according to any

preceding claim characterised in that the reactor element is provided with a distributor or manifold at one or both ends .

15. A compact reactor or method according to any

preceding claim characterised in that each or selected reactor tubes or reactor pipes are provided with a flow control device including a valve .

16. A compact reactor or method according to any

preceding claim characterised in that the curvature of the reactor element is from about 5° to 210°, typically from about 30° to 210°, preferably about 90°, about 120° or about 180°.

17. A compact reactor or method according to any

preceding claim characterised in that the straight reactor elements are arranged in substantially parallel relationship to each other.

18. A compact reactor or method according to any

preceding claim characterised in that some of the reactor elements are arranged to fold back or bend back upon others of the reactor elements or to be arranged in a stacking array one over the other or one above the other in a side-by-side array or combination of arrays .

19. A compact reactor or method according to any

preceding claim characterised in that the reactor is a plug flow reactor, preferable a continuous reactor or a reactor which is operated

substantially continuously.

20. A compact reactor or method according to any

preceding claim characterised in that the reactor is a turbulent reactor or causes the reactants to mix by turbulence.

21. A compact reactor or method according to any

preceding claim characterised in that the reactor is a single reactor or a combination of two or more reactor including groups of reactors arranged in modules or in trains of reactors .

22. A compact reactor substantially as hereinbefore

described with reference to the accompanying drawings.

23. A method substantially as hereinbefore described with reference to the accompanying drawings.