GB2565916A

GB2565916A - Chemical reaction assembly

Info

Publication number: GB2565916A
Application number: GB1812270.5A
Authority: GB
Inventors: Radley Mark; Deal Martyn; Moorhouse Simon
Original assignee: R B RADLEY AND CO Ltd
Current assignee: R B RADLEY AND CO Ltd
Priority date: 2016-06-01
Filing date: 2016-06-01
Publication date: 2019-02-27
Also published as: GB201812270D0

Abstract

A chemical reaction assembly 1 comprising a thermal block 3 operable to receive a reaction vessel, at least one thermoelectric element 5 to provide cooling to the thermal block and at least one resistive heater 7 to provide heating to the thermal block. Preferably the assembly further includes a removable insert where the insert includes a vessel receiving cavity 10 shaped to conform to an outer surface of the reaction vessel, the cavity may be dimensioned to receive a round-bottomed flask. Ideally the assembly includes a plurality of resistive heaters 7 and may be arranged symmetrically around the thermal block. Preferably the assembly further includes a heat sink 27 adjacent to each thermoelectric element which is in thermal contact with its respective thermoelectric element. Ideally at least one of the heat sinks comprises a first pedestal section 29 having a first face and one or more shoulders 31 adjacent to the first pedestal section such that a step is defined between the first pedestal section and the shoulder. The thermoelectric element maybe a Peltier element. A chemical reaction system comprising a housing including one or more chemical reaction assemblies is also claimed.

Description

CHEMICAL REACTION ASSEMBLY

Field of the invention

The invention relates to apparatus for performing chemical reactions or processes, and particularly but not exclusively to a modular chemical reaction assembly for performing a plurality of chemical reactions or processes simultaneously.

Background

When conducting a chemical reaction or process it is often desirable to heat and/or cool substances within a chemical reaction vessel. In order to facilitate the control and repeatability of a chemical reaction it can be desirable for these actions to be automated. This is particularly the case where lengthy and/or multi-stage chemical reactions are being conducted, so that a chemist operating the reaction does not need to closely attend to the reaction whilst it is underway.

It is known to provide a chemical reaction assembly which is capable of automatically heating and/or cooling the contents of a reaction at predetermined times. However, typically such chemical reaction assemblies require bespoke chemical reactor vessels in order to achieve good thermal transfer whereby the vessels are straight sided, and have bespoke lids to facilitate access to the vessel. However, these bespoke vessels restrict the versatility of the reaction assembly and can be problematic when transferring reactants to the chemical reaction assembly from a different piece of equipment prior to the reaction, or from the chemical reaction assembly to another piece of equipment after the reaction. Transferring reactants is inconvenient and can risk contamination or loss of the reactants, and can be hazardous if corrosive chemicals are being used. It is thus desirable to provide a chemical reaction assembly which is capable of use with standard laboratory glassware.

Furthermore, sometimes it is desirable to perform multiple chemical reactions at once. Whilst some modular reaction block assemblies are available which profess to have this capability, typically these modular assemblies are unable to provide satisfactory thermal isolation between adjacent reaction blocks. This means that use of all the modules is not possible if different temperatures are required simultaneously in adjacent reaction blocks, when extreme temperatures are required at opposite ends of heating and cooling, and thus the performance of the assemblies are compromised.

Where different temperatures are required simultaneously, it may be necessary to leave some blocks unused to provide a thermal buffer, or else make use of separate individual reaction assemblies. It is thus desirable to provide a modular reaction block assembly having improved thermal isolation between adjacent reaction blocks such that optimum performance may be maintained in all conditions.

Summary of the Invention

According to a first aspect of the invention there is provided a chemical reaction assembly comprising a thermal block operable to receive a reaction vessel, at least one thermoelectric element operable in use to provide cooling to the thermal block, and at least one resistive heater operable in use to provide heating to the thermal block.

It is known for chemical reaction assemblies to make use of thermoelectric elements, when commonly they provide both heating and cooling. However, we have found that although at first it might appear that using thermoelectric modules for both purposes is more efficient, in fact this is an inefficient way of achieving temperature control. Providing separate components for these separate functions allows the temperature to be controlled more efficiently. Furthermore, resistive heaters are able to achieve higher temperatures than current thermoelectric heaters.

The thermal block preferably includes a recess adapted to receive a reaction vessel, and preferably an industry standard chemical reaction vessel, such as a round bottomed flask. A removable insert may be disposed in the recess, the insert being adapted to conform the shape of the recess to the shape of an outer surface of a chemical reactor vessel. A plurality of such inserts may be provided, such that the inserts can be removed and replaced to alter the shape of the recess.

Typically chemical reaction assemblies of the type discussed in the background section are not compatible with round bottomed flasks because it is difficult to achieve good thermal transfer with a vessel of this shape - straight sided vessels are easier to heat/cool evenly. However, we have found that providing separate heating and cooling elements helps increase the efficiency of the thermal transfer.

Preferably the apparatus includes a plurality of thermoelectric elements, for example, two thermoelectric elements. The thermoelectric elements may be arranged substantially symmetrically around the thermal block. For example, the thermal block may have a footprint, and two thermoelectric elements may be arranged on opposing sides of the footprint. In one example, the footprint is rectangular or square, and the thermoelectric elements are arranged on opposite sides of the square, in thermal contact with opposite faces of the thermal block.

Preferably the apparatus includes a plurality of resistive heaters, for example, four resistive heaters. The resistive heaters may be arranged substantially symmetrically around the thermal block. For example, the thermal block may have a footprint, and the resistive heaters may be spaced evenly around the footprint. In one example, the footprint is rectangular or square, and the resistive heaters are arranged at the corners of the square.

The resistive heater(s) may be located within the thermal block, for example in one or more bores provided in the thermal block. The resistive heaters may be located within the corners of the thermal block.

We have found that the arrangement of heaters and coolers described above (i.e. two opposed thermoelectric elements and four evenly spaced resistive heaters) results in both even heating and cooling of even a round bottomed flask.

The assembly may further include a heat sink adjacent the or each thermoelectric element. Each heat sink may be in thermal contact with a respective thermoelectric element in order to remove heat from the thermoelectric element when it is in use. Each heat sink may comprise a pedestal section having a first face adapted to contact a first side of the thermoelectric element. One or more shoulders may be provided adjacent the pedestal section. A step may be located between the pedestal section and the or each shoulder such that the outer surfaces of the shoulders are displaced from the face of the pedestal section. This arrangement creates a larger gap between the heat sink and the thermal block than would be present if the heat sink had a flat face, which helps to thermally isolate the thermal block from the heat sink. If required, insulation can be located in the gap to improve the thermal isolation. The insulation may have a thickness which is greater than the thickness of the thermoelectric element, for example two, or three, or four times greater.

A block pedestal section may be provided on the thermal block having a face adapted to contact a second side of the thermoelectric element. One or more shoulders may be provided on the thermal block adjacent the block pedestal section. A step may be located between the block pedestal section and the or each shoulder such that the outer surfaces of the shoulders are displaced from the face of the block pedestal section. This arrangement creates a larger gap between the heat sink and the thermal block than would be present if the thermal block had a flat face, which helps to thermally isolate the thermal block from the heat sink.

The or each heat sink may be mounted to the thermal block. The mounting may be achieved using one or more, and preferably a pair of, fixings such as screws passing from the heat sink to the thermal block. This arrangement is such that each thermoelectric element is sandwiched and secured between a respective heat sink and the thermal block, avoiding the need to pass screws or other fixing members through the thermoelectric element itself, which would reduce the efficiency of the cooling.

The fixing members may each include a biasing mechanism, such as a spring washer, in order to achieve an even mounting of the thermoelectric element in the event of thermal expansion or contraction. The fixing members may include insulation, such as an insulating sleeve to further improve the thermal isolation of the thermal block from the heat sink.

The assembly may further include control electronics in communication with the or each thermoelectric element and the or each resistive heater. The control electronics may be operable to cause the thermoelectric element(s) and resistive heater(s) to cool and/or heat the thermal block in a user-selectable manner.

The assembly may include a housing. A support tray may be provided in the housing, and the thermal block may be mounted on the support tray. Insulating material may be provided between the thermal block and the support tray and between the support tray and the housing. Mounting screws to secure the support tray to the thermal block may also be insulated with the means of an insulating sleeve. This helps to minimize heat transfer between the thermal block and the housing.

The housing may be operable to catch condensate formed on components within the housing, particularly the thermoelectric element and/or heat sink and/or thermal block.

The housing may be shaped to channel the condensate away from the control electronics.

The thermal block may be resiliently mounted within the housing. In one example, the thermal block and support tray assembly may be mounted to the housing via a resilient mounting mechanism, such as a spring mounting.

The housing may be located within an external casing including a lower chassis and a lid secured to the lower chassis. The lid may comprise an aperture through which the recess of the thermal block may be accessed, so that a chemical reaction vessel can be placed in the recess whilst the lid is secured in place. The assembly may be sized such that when the lid is secured in place the resilient mounting mechanism is at least partly compressed. This helps to secure and align the components beneath (e.g. the thermal block and any insulation covering the thermal block).

A notch may be provided adjacent an upper edge of the recess in the thermal block, and preferably encircling the recess. An insulating collar may be provided adjacent the aperture in the lid, and preferably encircling the aperture. When the lid is secured in place, the insulating collar is preferably received in the notch in the thermal block. This provides a seal between lid and thermal block and improves the thermal separation between the lid and the thermal block, and helps prevent heat being lost to the lid, which in turn helps to avoid the lid from getting too hot or cold to touch.

In examples where an insert is disposed within the recess in the thermal block, a channel may be provided around the insert, the channel located such that when the insert is received in the recess a void is formed between the collar and the insert. Again, this improves the thermal isolation of the lid from the actively heated/cooled parts of the assembly.

According to a second aspect of the invention there is provided a modular reaction system comprising a plurality of chemical reaction assemblies of the type discussed above with reference to the first aspect of the invention.

The plural reaction assemblies may be arranged side by side, such that the reaction assembles are located adjacent one another when the modular reaction system is placed on a horizontal surface, such as a workbench.

Although the above statements of the invention have been set out with respect to assemblies including resistive heaters, it will be appreciated that many of the features of the invention would be advantageous when used with a system which includes only thermoelectric elements, e.g. thermoelectric elements used for both heating and cooling. For example, the heat sink mounting system, and in particular the provision of a shoulder, would be useful in a system with no separate heating elements.

Thus, according to a third aspect of the invention, a chemical reaction assembly is provided comprising a thermal block operable to receive a reaction vessel, at least one thermoelectric element operable in use to provide cooling and/or heating to the thermal block, and at least one heat exchanger adjacent the thermoelectric element to heat and/or cool the thermoelectric element, wherein at least one of the heat sink and the thermal block comprises a pedestal section having a first face adapted to contact a first side of the thermoelectric element and one or more shoulders adjacent the pedestal section such that the outer surfaces of the shoulders are displaced from the face of the pedestal section. Pedestal sections may be provided on both the heat exchanger and the thermoelectric element, as discussed above, if required. Insulation may further be included between the heat exchanger and the thermal block, as discussed above, if required.

Similarly, the collar discussed above would be useful to isolate a thermal block from a lid in chemical reaction assembly systems having different heating/cooling provisions to those described above.

Thus, according to a fourth aspect of the invention, there is provided a chemical reaction assembly comprising a thermal block disposed within a casing including a lower chassis and a lid, the thermal block including a recess operable to receive a reaction vessel and a notch adjacent an upper edge of the recess, wherein the lid comprises an aperture through which the recess of the thermal block may be accessed, and wherein the apparatus further comprises an insulating collar located adjacent the aperture in the lid such that when the lid is secured to the lower chassis the insulating collar is received in the notch in the thermal block.

The assembly may further include an insert disposed within the recess in the thermal block. A channel may be provided around the insert, the channel located such that when the insert is received in the recess a void is formed between the collar and the insert when the lid is closed.

The assembly may further include a heating and/or cooling arrangement operable in use to provide heating and/or cooling to the thermal block. An example of such an arrangement is the thermoelectric element cooling system and resistive heating system discussed above.

The skilled man will further appreciate that other features of the inventions discussed above, such as the support tray arrangement described above, would also be useful in other chemical reaction assembly systems having different heating/cooling provisions to those described above.

The skilled man would thus appreciate that any of the features of the various aspects of the invention discussed above can be applied separately and/or combined together as required, even if that separate use and/or combination is not explicitly enunciated herein.

Brief Description of the Drawings

The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a chemical reaction assembly for use with a single reaction vessel;

Figure 2 is an exploded perspective view of the chemical reaction assembly of Figure 1;

Figure 3 shows a cross section through the chemical reaction assembly of Figure 1 in a first plane;

Figure 4 shows a cross section through the chemical reaction assembly of Figure 1 in a second plane at 90 degrees to the first plane;

Figure 5 is a cross section through the heat sink mounting arrangement of the chemical reaction assembly of Figure 1;

Figure 6 is an exploded bottom perspective view of the chemical reaction assembly of Figure 1;

Figure 7 is a perspective bottom view of the chemical reaction assembly of Figure 1 additionally showing a support tray;

Figure 8 is a perspective view of a modular reaction system including four chemical reaction assemblies of the type shown in Figure 1;

Figure 9 shows a cross section of a detail of the support tray mounting arrangement;

Figure 10 shows a bottom view of the assembly and support tray shown in Figure 7;

Figure 11 shows a detail of lid and collar assembly for use with the chemical reaction assembly of any of the Figures above;

Figure 12 shows a chemical reaction assembly and housing located in a lower chassis; and

Figure 13 shows a cross section through a chemical reaction assembly and housing included in an external casing.

Detailed Description

Referring initially to Figure 1 a perspective view of chemical reaction assembly 1 is shown. The same chemical reaction assembly 1 is shown in an exploded perspective view in Figure 2. The chemical reaction assembly 1 includes a thermal block 3 which is operable to receive a reaction vessel, together with at least one thermoelectric element 5 operable in use to provide cooling to the thermal block and at least one resistive heater 7 operable in use to provide heating to the thermal block.

Referring to Figures 3 and 4, two cross sections are shown through a chemical reactor apparatus which is similar to that shown in Figures 1 and 2. In the example of Figure 3 the thermal block 3 is adapted to receive an industry standard chemical reaction vessel, such as, in this case, a round bottomed flask 9. To this end an insert 11 is located within a recess 10 in the thermal block. The insert 11 includes a vessel receiving region 13 which is shaped to ensure good thermal contact with the vessel with which it is intended for use. In the example shown the vessel receiving region 13 includes a substantially hemispherical cavity, such that a substantially spherical round bottomed flask which is placed in the cavity achieves thermal contact with the insert over the majority of its outer surface 15 (or at least that part of its outer surface which is located in the cavity). In the event that a vessel having a different shape is to be used with the chemical reaction assembly, an insert having a differently shaped vessel receiving region may be used. The aim is for the vessel to fit closely inside the insert such that good thermal contact is achieved.

The shape of the industry preferred reaction vessel (a round bottomed flask) is nonoptimal for heat transfer from either a thermoelectric device or resistive heaters. For example, only the lower half of the flask can be in thermal contact. The requirement to also provide the facility to heat and cool other reaction vessel types with different profiles within the same device results in the provision of a series of insert blocks with matching profiles to accommodate the different vessel types. Both these factors result in the thermoelectric devices and resistive heaters being positioned away from the reaction vessel, with suboptimal thermal surface area contact. For this reason the placement of the thermoelectric modules and resistive heaters has been carefully selected in the example shown to ensure good thermal transfer, as well as even heating and cooling profiles, in view of the limitations imposed by the use of a round bottomed flask and/or an insert within the block.

Referring again to Figure 2, the thermoelectric elements 5 are, in this example, peltier elements. The apparatus 1 includes a plurality of thermoelectric elements 5, in particular, two peltier elements. The peltier elements are arranged substantially symmetrically around the thermal block 3. The thermal block has a substantially square footprint (i.e. appears substantially square when viewed from above in plan). The two thermoelectric elements 5 are arranged on opposing sides of the thermal block, in thermal contact with (and in particular, in physical contact with) opposite faces of the thermal block. The thermoelectric modules are, in this example, able to provide cooling to less than -20°C, and preferably to at least -40°C.

The apparatus 1 also includes a plurality of resistive heaters 7, in particular, four resistive heaters. The resistive heaters are arranged substantially symmetrically around the thermal block 3, in this case at or adjacent the corners of the block. The resistive heaters are able to provide heating to greater than +160°C, and preferably to at least +180°C. In order to further increase thermal efficiency the resistive heaters 7 are, in this example, integrated within the thermal block itself.

The thermal block is composed of a material having good thermal conductivity, such as a metal. In the example shown, the thermal block is formed of aluminium, which is both an excellent conductor and relatively light. Bores or channels 15 are machined or otherwise formed into the block to house the resistive heaters.

Similarly, the insert 11 is also composed of a material which is a good thermal conductor, such as a metal. Again, in the example shown, the insert is formed from aluminium. The outer surface of the insert is shaped to fit closely within the recess in the thermal block to ensure good thermal transfer between the two components effectively, the insert acts as an extension of the thermal block.

Referring now to Figure 8, a modular chemical reaction system 100 is shown, which includes a plurality of chemical reaction assemblies 1 of the type discussed above. In particular four reaction assemblies are shown arranged side by side, such that the reaction assembles are located adjacent one another in a line when the modular reaction system is placed on a horizontal surface, such as a workbench. Each reaction assembly is able to operate independently of each other reaction assembly, and each assembly can independently achieve heating and cooling in the range -40°C to + 180°C. It will be appreciated that both thermal efficiency within each assembly and thermal isolation between adjacent assemblies is important in such a reaction system. For example, adjacent assemblies might simultaneously be operating at opposite ends of the operating temperature range. Additionally, in the case of the middle two reaction assemblies, each assembly might have adjacent assemblies on its two side operating at opposite temperature extremes (e.g. one hot, and one cold). Thermal isolation from adjacent assemblies is thus of extreme importance.

Turning back to Figures 1-3, it can be seen that thermally insulating materials 17 and 25 are provided surrounding the thermal block. The insulating material is selected to balance the requirement to minimise thermal loss with the requirement to minimise the overall thickness of the material used, so as to achieve an acceptable footprint for the assembly. Minimising thickness is also useful to permit use of a magnetic stirring device 19, such that magnetic coupling can be attained between the device and a magnetic stirrer located in the reaction vessel itself (not shown). The material preferably should also have good chemical resistance, and be able to withstand the operating temperature range of -40C to +180C. The material shown in the examples is a durable foam insulation, such as a polyamide or nylon foam. An example of a suitable foam is Zotek® NB50, a polyamide foam based on nylon 6 and having a density of 50kg/m³. The material shown in the examples is approximately 10-12mm thick. However, it will be appreciated that a different thickness of insulation may be appropriate if a different material is used and/or if a different operating temperature range is required.

The insulating material surrounds as much of the outer surface of the thermal block as possible, in order to provide the best insulation possible. An insulating cover 20 is shaped to fit over the upper surface of the thermal block (“upper” refers to the intended orientation in use). An aperture 21 is provided in the insulation through which in use the insert and/or reaction vessel can be placed within the recess of the thermal block. The aperture 21 has substantially the same diameter as the diameter of the recess in the thermal block.

The cover 20 is further shaped to cover the sides of the thermal block. A slot 23 is formed in the insulating cover 20 to permit the thermoelectric element 5 to cool the thermal block directly. The slot has substantially the same cross-sectional dimensions as the thermoelectric element, in order to ensure that the insulation fits closely around the thermoelectric element.

Additional insulating material 25 is provided adjacent the lower side of the thermal block (“lower” refers to the intended orientation in use). As shown in Figures 5-7 , the base of the thermal block includes a thinner region 26, i.e. a portion having a reduced thickness in comparison with the thickness of the remainder of the base. This helps effect a good magnetic coupling between a magnetic stirring device 19 and a magnetic stirrer located in the reaction vessel. It also permits additional insulating material 25 to be located in a recess provided in the base.

The assembly further includes a heat sink 27 adjacent each thermoelectric element 5. Each heat sink 27 is in thermal contact with a respective thermoelectric element 5 in order to remove heat from the thermoelectric element when it is in use.

Ideally, a large heat sink having large internal heat transfer channels would be provided in order to remove as much heat as possible from its respective thermoelectric element to help achieve maximum cooling. However, it is necessary to balance this requirement with the need to avoid excessive thermal transfer between the heat sink and the thermal block itself - it is not desirable for the heat sink to also cool the thermal block. Thermoelectric elements themselves are relatively compact, and providing a heat sink which has the same cross sectional dimensions as the thermoelectric element would not provide sufficient cooling to achieve the required minimum temperature of -40°C. However, providing a heat sink having a larger cross section risks thermal transfer between the heat sink and the thermal block itself, which would reduce the overall efficiency of the assembly.

To this end, a mounting arrangement between the heat sink 27 and the thermal block 3 has been designed such that the size of the heat sink and liquid channels within it is sufficient to take away heat from one surface of the thermoelectric device, but thermal transfer is minimised between the thermal block and the heat sink. In particular, the thermoelectric device is mounted between pedestal sections on both the thermal block and the heat exchanger to create a void between the heat sink and the thermal block. Insulating material can then be positioned in this void to create a thermal barrier.

As best shown in Figure 2, each heat sink comprises a first pedestal section 29 having a first face adapted to contact a first side of the thermoelectric element (i.e. the side which is not in contact with the thermal block). Each heat sink further includes a shoulder 31 on either side of the pedestal section such that a step 33 is formed between the pedestal section and each adjacent shoulder. The heat sink thus has a substantially T shaped cross section, when viewed in plan. That is, the surfaces of the shoulders facing the thermal block are displaced from the face of the pedestal section, away from the thermal block, creating a larger gap between the heat sink and the thermal block than would be present if the heat sink simply had a flat face.

Similarly a second pedestal section 35 is provided on the thermal block having a second face adapted to contact the second side of the thermoelectric element (i.e. the side which, in use, is operable to cool the thermal block). A shoulder is provided on the thermal block adjacent each side of the block pedestal section such that a step is formed between the block pedestal section and each adjacent shoulder. Thus the outer surfaces of the shoulders which are facing toward the heat sink are displaced from the face of the block pedestal section, creating a larger gap between the heat sink and the thermal block than would be present if the thermal block had a flat face. It is not necessary for the step on the thermal block to be the same size as the step on the heat sink(s).

Provision of pedestal sections on either or both of the thermal block and the heat sink(s) means that more insulating material 17 can be provided between each heat sink and the thermal block than if the heat sink and the block both had a flat outer surface. In that case, the amount of insulation would be limited to the thickness of the thermoelectric element. In the example shown however, the insulation is more than twice as thick as the thermoelectric element, for example three times as thick, or four times as thick. This improves the thermal isolation of the block. Furthermore, a larger heat sink can be used if required - the heat sink is not limited to having the same cross sectional dimensions as the thermoelectric element. This improves the efficiency with which heat can be removed from the thermoelectric elements, allowing lower temperatures to be reached.

The or each heat sink is, in the example shown, mounted to the thermal block (rather than to the thermoelectric elements). The mounting is achieved using one or more, and preferably a pair of, fixings such as screws or bolts 37 passing from the heat sink to the thermal block such that each thermoelectric element is sandwiched between a respective heat sink and the thermal block. The bolts pass on either side of a respective thermoelectric element, rather than through the thermoelectric element, avoiding the risk of damage to the delicate thermoelectric element and also maximizing the surface area which is given over to cooling.

The bolts 37 each include a biasing mechanism, such as a spring washer 39, in order to achieve an even mounting of the thermoelectric element, and improve the tolerance of the mounting to thermal expansion or contraction. Each fixing member is insulated using an insulating sleeve 41 to further improve the thermal isolation of the thermal block from the heat sink. Additionally, the exposed bolt head can be enclosed in the thermally insulated material to further restrict loss to the surroundings (not shown).

The bolts 37 are formed of metal, such as aluminium or steel, positioned in mechanically stable, thermally insulated sleeves. Ideally these sleeves are made from

PEEK (polyether ether ketone).

If required, the insulating material disposed between the heat sink and the thermal block may have a thickness which is less than the distance between the heat sink and the thermal block when the heat sink is mounted to the thermal block. This arrangement results in a void 43 being defined between the thermal block and the heat sink (and in particular, in the example shown, between the insulating material and heat sink). This increases airflow around the heat sink, improving cooling, and also provides an additional insulating buffer between the heat sink and the thermal block.

The assembly further includes control electronics (not shown) in communication with the thermoelectric elements and the resistive heaters. The control electronics are operable to cause the thermoelectric elements and resistive heaters to cool and/or heat the thermal block in a user-selectable manner.

The assembly is enclosed within a housing, such as the housing 110 which is shown in the modular system of Figure 8, or the housing 110 shown in Figures 12 and 13. It is desirable to minimize heat transfer between the thermal block and the housing, and to this end a support tray 45 is provided in the housing, and the thermal block is mounted on the support tray.

Mounting of the thermal block assembly to the support tray is achieved with fixings 47, e.g. metal bolts, positioned in mechanically stable, thermally insulated sleeves 49 located through the support tray and the insulating material 25 which surrounds the thermal block. In this way, thermal transfer through the bolt to the support tray is minimised. Additionally, the exposed metal bolt head can be enclosed in thermally insulated material to further restrict loss to the surroundings. If required, resilient washers 51 can be included between the sleeve and bolt head to improve the tolerance of the mounting to heating and cooling.

The support tray is useful to raise the thermal block above the base of the housing, and so permit airflow to the control electronics beneath the heating/cooling components. The housing helps to thermally isolate the electronics from the thermal block. Finally, the housing is also useful to catch condensate formed on components within the housing, particularly the thermoelectric elements and/or heat sinks and/or thermal block. The housing is shaped to channel any such condensate away from the control electronics, and ideally out of the external casing 115 of the system or to a collection region within the external casing.

The support tray includes a stirrer aperture 53, which is substantially centrally placed in the example shown, to facilitate use of the magnetic stirring assembly 19, as well as two heat sink apertures 55 located such that fluid inlet and outlet channels can be connected to the heat sinks 27 in use.

In a modular assembly of the type shown in Figure 8, one support tray is provided per thermal block. This improves the ease of mounting the thermal block assemblies within the housing, and also improves thermal isolation between adjacent blocks. Alternatively, if required, one support tray could be provided for all four thermal blocks (or however many are present).

Each thermal block is resiliently mounted within the housing via a resilient mounting mechanism, such as a spring mounting.

The housing 110 is mounted within a lower chassis 120 and additionally enclosed with a lid 57 (see Figures 11-13). Together the lower chassis 120 and lid 57 form an external casing 115 for the reaction apparatus. The lid comprises an aperture through which the recess of the thermal block may be accessed, so that a chemical reaction vessel can be placed in the recess whilst the lid is secured in place. In the case of the modular apparatus 100, multiple apertures are provided in the lid, one for each reaction block assembly.

The assembly is sized such that when the lid is secured in place the resilient mounting mechanism is at least partly compressed. That is, the thermal block is pushed downwardly, toward the base of the housing, by the lid when the lid is secured. This helps to secure and align the lid and the components beneath (e.g. the thermal block and any insulation covering the thermal block). The lid may be secured to the lower chassis by any suitable mechanism, e.g. screws or bolts, such that the thermal block assembly, including housing, support tray and insulation, as well as the control electronics, are enclosed within the casing.

In the case of the modular system, resiliently mounting each thermal block separately means that it is not necessary to assemble the system to extremely high tolerances in order to ensure that each thermal block is mounted at the same height within the housing. Indeed, it can be advantageous to bias the thermal blocks upwardly, such that when the lid is secured the resilient mounting means are necessarily compressed, thus levelling all the blocks to the same height (i.e. that of the internal face of the lid).

The sealing between the lid and the thermal block(s) is, in the examples shown, achieved using a collar 59, which is ideally made from a material which is both thermally insulating and chemically resistant, such as polytetrafluoroethylene (PTFE). A notch 61 is provided adjacent an upper edge of the recess 10 in the thermal block, and preferably encircling the recess so as to provide a circumferential ledge around the edge of the recess. The insulating collar is located around the aperture in the lid. In the example shown the collar includes a groove 63 in its outer circumference, within which an edge 65 of the lid (defined by the aperture) is located. Thus the collar completely encircles the aperture providing a rim around the aperture.

The circumferential dimensions of the collar (in this case, the collar’s diameter) are substantially the same as the circumferential dimensions (in this case, the diameter) of the ledge around the recess in the thermal block. Thus, when the lid is secured, the insulating collar is received in the notch in the thermal block. The collar fits through the outer casing, passing through the thermally insulating layer 20 and locating in the notch 61 of the thermal block. The collar protrudes in such a way that when an insert block 11, containing a reaction vessel is positioned in the thermal block 3, the collar provides a full barrier between the thermal block and insert, and the outer casing. In this way thermal transfer between the thermal block and the outer casing is minimised. Additionally, a seal is formed between the lid and the thermal block thus preventing any liquids or other materials accessing the gap between the lid and the thermal block, or any insulation that may be present in this gap.

Furthermore, the apparatus is arranged such that contact between the insert and collar is avoided. In the example shown, the insert features a channel 67, which defines a region of the insert having a diameter which is smaller than the diameter of the portion of the insert which is received in the recess 10 of the thermal block. The channel 67 is located such that when the insert is received in the recess a void 69 is formed between the collar and the insert when the lid is secured. This helps to ensure that there is no thermal transfer path by conduction from the insert to the external casing. Again, this improves the thermal isolation of the lid from the actively heated/cooled parts of the assembly. Additionally (or alternatively), the portion of the collar which is received in the notch has a thickness which is less than a width 62 of the notch. This increases the size of the void 69 between the collar and the insert, further improving the thermal isolation of the lid from the insert.

Using the heating and cooling system described above, together with the various improved insulation and mounting systems, an extremely efficient chemical reaction assembly can be produced. The assembly is capable of achieving heating and cooling covering the range -40°C to +180°C. This is even the case in the modular system described - adjacent assemblies within the system can achieve temperatures at opposite ends of the above range independently if required.

It will be appreciated that a modular system could be produced having fewer than four reaction assemblies, for example two or three. Furthermore, a modular system could be produced having more than four reaction block assemblies, e.g. five, or six, or more. The assemblies need not be arranged in a linear footprint, as shown in Figure 8, but could be arranged differently, e.g. in a square or rectangular footprint.

Although the invention has been primarily described with respect to assemblies including resistive heaters, it will be appreciated that many of the other features of the invention would be advantageous when used with a system which includes only thermoelectric elements, e.g. thermoelectric elements used for both heating and cooling. For example, the heat sink mounting system, and in particular the provision of one or more pedestal regions, would be useful in a system with no separate heating elements.

Similarly, the lid and associated insulation system discussed above (and in particular the use of a collar and void to isolate the thermal block and/or an insert within the thermal block from the housing) would be useful to isolate a thermal block from a lid in chemical reaction assembly systems having different heating/cooling provisions to those described above.

Furthermore, the support tray arrangement described above would also be useful in other chemical reaction assembly systems having different heating/cooling provisions to those described above.

Claims

1. A chemical reaction assembly comprising a thermal block operable to receive a reaction vessel, at least one thermoelectric element operable in use to provide cooling to the thermal block, and at least one resistive heater operable in use to provide heating to the thermal block.

2. The chemical reaction assembly of claim 1, wherein the thermal block includes a recess adapted to receive a reaction vessel.

3. The chemical reaction assembly of claim 2, where in the assembly further includes a removable insert disposed, in use, in the recess, the insert including a vessel receiving cavity shaped to conform to an outer surface of the reaction vessel.

4. The chemical reaction assembly of claim 3, wherein the cavity is dimensioned to receive a round bottomed flask.

5. The chemical reaction assembly of any preceding claim, wherein the assembly includes a plurality of thermoelectric elements.

6. The chemical reaction assembly of claim 5, wherein the thermoelectric elements are arranged on opposing sides of a footprint of the thermal block, so as to provide cooling to opposing faces of the thermal block.

7. The chemical reaction assembly of any preceding claim, wherein the assembly includes a plurality of resistive heaters.

8. The chemical reaction assembly of claim 7, wherein the resistive heaters are arranged substantially symmetrically around the thermal block.

9. The chemical reaction assembly of claim 8, wherein For example, the thermal block has a substantially square footprint, and the resistive heaters are arranged adjacent the corners of the square.

10. The chemical reaction assembly of any preceding claim, wherein the resistive heater(s) are located within the thermal block.

11. The chemical reaction assembly of any preceding claim, wherein the assembly further includes a heat sink adjacent the or each thermoelectric element, and in thermal contact with its respective thermoelectric element in order to remove heat from the respective thermoelectric element when it is in use.

12. The chemical reaction assembly of claim 11, wherein at least one of the heat sinks comprises a first pedestal section having a first face adapted to contact a first side of the thermoelectric element and one or more shoulders adjacent the first pedestal section such that a step is defined between the first pedestal section and the or each shoulder such that an outer surface of the or each shoulder is displaced from the face of the first pedestal section.

13. The chemical reaction assembly of claim 12, wherein a gap is defined between the outer surfaces of the shoulders of the heat sink and an outer surface of the thermal block, and wherein insulating material is located in the gap.

14. The chemical reaction assembly of any preceding claim, wherein second pedestal section is provided on the thermal block having a second face adapted to contact a second side of the thermoelectric element and one or more shoulders adjacent the second pedestal section such that a step is defined between the second pedestal section and the or each shoulder such that an outer surface of the or each shoulder is displaced from the face of the second pedestal section.

15. The chemical reaction assembly of any preceding claim, wherein the or each heat sink is mounted to the thermal block using one or more fixings passing from the heat sink to the thermal block such that each thermoelectric element is sandwiched between a respective heat sink and the thermal block.

16. The chemical reaction assembly of claim 15, wherein the one or more fixings each include a biasing mechanism and/or insulation.

17. A chemical reaction system comprising a housing including one or more chemical reaction assemblies as claimed in any preceding claim.

18. The chemical reaction system of claim 17, wherein the system comprises a plurality of chemical reaction assemblies as claimed in any one of claims 1 to 16.

19. The chemical reaction system of any preceding claim, wherein the system further includes one or more support trays disposed within the housing, the or each thermal block being mounted on a respective support tray with thermally insulated mountings.

20. The chemical reaction system of claim 19, wherein the system further includes control electronics in communication with the or each thermoelectric element and the or each resistive heater.

21. The chemical reaction system of claim 19 or claim 20, wherein the housing is operable to catch condensate formed on components within the housing.

22. The chemical reaction system of any one of claims 17 to 21, wherein the or each thermal block is resiliently mounted within the housing. .

23. The chemical reaction system of claim 22, wherein the housing is located within a casing including a lower chassis and a lid, and wherein the housing is sized such that when the lid is secured to the lower chassis the resilient mounting mechanism is at least partly compressed.

24. The chemical reaction system of any one of claims 17 to 23, wherein the housing is located within a casing including a lower chassis and a lid, and wherein a notch is provided adjacent an upper edge of a reaction vessel receiving recess in a thermal block, and an insulating collar is provided adjacent an aperture in the lid, the collar and notch being located such that when the lid is secured in place the collar is received in the notch in the thermal block.

25. The chemical reaction system of claim 24, the system further comprising an insert disposed within the recess in the thermal block, wherein a channel is provided around the insert, the channel located such that when the insert is received in the recess a void is formed between the collar and the insert.