Apparatus and method for temperature controlled processes

Abstract

Method and apparatus for temperature controlled processes in a vessel to provide improved process control, in particular to enable controlled temperatures to be applied to a substance in different process zones of a vessel, has a series of tubular members arranged and operatively connected in a flow system, and each process zone has temperature regulating means juxtaposed thereto for effecting temperature control therein.

Claims

1. A continuously controlled crystallisation process applied to an at least partially fluid media according to a predetermined regime, comprising: forming a continuous flow system for fluid media from a plurality of cylindrical tubes operatively connected to permit fluid communication therethrough, each cylindrical tube providing a discrete process zone, the cylindrical tubes being configured to follow a succession of return paths in one plane and being arranged and operatively connected to form at least one continuous fluid flow path having an inlet and an outlet; providing in each cylindrical tube a plurality of orificed plates that extend radially inwards towards the center of the cylindrical tubes; providing temperature regulating means for effecting independent temperature control over the discrete process zones, the temperature regulating means including a shell that surrounds the cylindrical tubes forming the continuous fluid flow path, a source of a single temperature controlled fluid, a manifold that supplies the temperature controlled fluid, a plurality of branches that extend from the manifold, wherein each branch supplies the temperature controlled fluid to a portion of the shell surrounding each of the discrete process zones, and a plurality of valves, each valve being provided on a branch that extends from the manifold to a portion of the shell surrounding each of the discrete process zones; introducing fluid media to the flow system; imparting oscillatory motion to the fluid media to initiate and maintain uniform mixing and efficient dispersion thereof; controlling the temperature of at least one of the discrete process zones by controlling the flow rate of the temperature controlled fluid through a section of the shell corresponding to the at least one discrete process zone; and selectively precipitating a crystalline solid.

2. The process of claim 1, wherein the temperature within the at least one discrete process zone is varied in C. per meter.

3. The process of claim 1, wherein the temperature within the at least one discrete process zone is varied in C. per minute.

4. The process of claim 1, wherein controlling the temperature of at least one discrete process zone comprises independently controlling the temperatures of a plurality of the discrete process zones by independently controlling flow rates of the temperature controlled fluid through portions of the shell corresponding to the plurality of discrete process zones.

5. The process of claim 4, wherein independently controlling the temperatures of a plurality of the discrete process zones comprises adjusting the temperatures of the plurality of discrete process zones such that the rate of temperature change of the fluid media is substantially consistent along the plurality of discrete process zones.

6. The process of claim 4, wherein independently controlling the temperatures of a plurality of the discrete process zones comprises adjusting the temperatures of the plurality of discrete process zones such that the rate of temperature change of the fluid media is inconsistent along the plurality of discrete process zones.

7. The process of claim 4, wherein independently controlling the temperatures of a plurality of the discrete process zones comprises adjusting the temperatures of the plurality of discrete process zones such that the rate of temperature change of the fluid media is linear along the plurality of discrete process zones.

8. The process of claim 4, wherein independently controlling the temperatures of a plurality of the discrete process zones comprises adjusting the temperatures of the plurality of discrete process zones such that the rate of temperature change of the fluid media is non-linear along the plurality of discrete process zones.

9. The process of claim 1, wherein controlling the temperature further comprises setting a starting temperature at a first end of the continuous flow system and a finishing temperature at a second end of the continuous flow system to predetermined constant values.

10. The process of claim 1, comprising the further step of adjusting the process conditions by introducing or extracting media as necessary.

11. The process of claim 10, comprising the further step of adding crystallization seeds to promote crystallization.

12. The process of claim 11, wherein the crystallization seeds promote the crystallization of only one enantiomer from a racemic mixture.

13. The process of claim 12, comprising the further step of collecting the crystallized enantiomer using at least one filter.

14. The process of claim 13, comprising the further step of crystallizing and collecting the opposite enantiomer.

15. The process of claim 14, wherein the crystallization and collection of the two opposite enantiomers is alternated between the two opposite enantiomers.

16. The process of claim 14, wherein the crystallization and collection of the two opposite enantiomers is simultaneous.

17. The process of claim 13, comprising the further step of diverting the flow of the fluid media along disparate cylindrical tubes of the continuous flow system by way of a manifold.

Description

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

(2) FIG. 1 is a schematic view of a serpentine flowpath oscillatory baffled apparatus suitable for carrying out temperature controlled processes;

(3) FIG. 2 is a schematic view of an oscillatory baffled apparatus containing a Y-junction, suitable for carrying out temperature controlled processes;

(4) FIG. 3 is a graph that illustrates a linear cooling profile achieved with the present apparatus; and

(5) FIGS. 4a and 4b illustrate the different crystal morphologies obtained using different cooling rates.

(6) Referring now to FIG. 1 there is shown a process apparatus 101 comprising a jacketed vessel 102 encased by a shell 103. The shell 103 contains fluid which acts as global temperature regulation means. The shell 103 has fins (not shown) attached to its internal surface to promote local turbulence in order to enhance the efficiency of cooling or heating. Thermal isolation laggings (not shown) can be applied to the shell 103 to maximise the cooling or heating effect. A series of branches 104 connected to a temperature manifold 105 form a local temperature regulation means. Control valves 109 are placed at points on the local temperature regulation means to divert heating or cooling as the user desires. The arrows superposed on the local temperature regulation means indicate the counter-current direction of flow for a coolant or heating fluid. The local temperature regulation means is equipped with a cooling/heating tank 114 and a pump 115.

(7) The vessel 102 has a plurality of substantially parallel tubular members 106 joined together by U-bends 107 in a serpentine fashion. The vessel 102 contains baffles 108, which are arranged in cells. The number of cells, tubular members and U-bends is not limited. Attached to the vessel 102 at the reactant feed end are a feed tank 112 and a pump 113. Between the pump 113 and the vessel 102 there is positioned a flow meter 117 and an input control valve 118. At the product collection end of the vessel 102 there is connected a centrifugal separator or a collecting tank 116.

(8) The feed tank 112 and pump 113 act as a supply means to supply a feed of at least one flowable media to the vessel 102.

(9) The baffles 108 extend inwardly from interior surfaces of the tubular members 106 which are provided as cylindrical tubes. The baffles 108 are provided as orificed plates extending radially inwards towards the centre of the cylindrical tubes, and mounted on rails (not shown) attached to the inner surfaces of the tubular members 106.

(10) The vessel can be made from separate units, taking the form of individual cells connected by individual U-bends.

(11) Alternatively, the vessel can take the form of a single unit, for example a continuous extrusion formed in a desired configuration, or any other structure suitable for forming a continuous flow path. Also, whilst in this example the vessel is, for illustrative purposes, shown as a succession of tubular cells, arranged in parallel and in one plane with return ends (U- or C-bends) to present a serpentine form, it will be understood that it can be of any other convoluted shape, for reasons of compactness, provided that the discrete zones of same are suitable for the application and maintenance of different temperatures. The tubular members can be configured to follow a succession of return paths in one plane.

(12) At one end of the vessel 102 there is a piston 110 to impart oscillatory motion to the contents of the vessel 102. However, other oscillation means can also be used. Control means (not shown) are provided to control both the stroke length and the frequency of oscillation of the piston. The control means is operatively connected to the vessel 102 and is adapted to effect continuous or plug flow of media through the vessel 102. The flow control means can also be adapted to initiate and maintain uniform mixing and efficient dispersion of at least one fluid in the vessel 102, and/or the can be adapted to apply a net flow Reynolds number >100 on at least one fluid.

(13) A number of inlet and outlet ports 111 are situated along the length of the vessel 102, the ports being designed to allow species, seeds or any other additive to be added and/or removed from the tubular member. In addition, the ports provide means for sensing some property of the contents of the tubular member, such as temperature, turbidity and pH. The ports can also provide means for mounting X-ray diffraction (XRD), ultrasonic/Raman spectroscopy (USS) or similar instrumentation along the tubular member to monitor the shape and size of crystals in-situ. The inlet and outlet ports 111 can also be used as process regulating means, operatively connected to the tubular members 106.

(14) In this embodiment a filter or filters can be used in the vessel 102 to selectively remove a substance from inside the vessel 102. For example, when the product of a reaction is crystallised, a particular size distribution, shape or form of crystal can be selectively removed continuously from the vessel 102 using the filters.

(15) The apparatus can have other process regulating means comprising means for introducing and extracting media, such as fluid inlet and/or outlet means for the addition or extraction of fluids or a port for venting a substantially fluid substance.

(16) The temperature regulation along the vessel 102 consists of a global cooling/heating loop in the form of a shell 103 arranged in counter-current fashion in relation to the solution input. The temperature regulation also consists of a local temperature manifold 105 attached to individual branches 104 associated with the individual tubular members 106 of the vessel 102. The local temperature regulation means is connected to the global temperature regulation means in order to enhance local control of temperature.

(17) The temperature manifold, branches and control valves enable the temperature of each branch to be controlled independently from the remaining branches. The branches act as local temperature regulating means and are operatively connected to the shell which acts as global temperature regulating means. Consequently, this apparatus allows the temperature of each tubular member to be independently or collectively controlled.

(18) For example, in a controlled cooling process each branch can be set to an incrementally lower temperature; and in a controlled heating process, each branch can be set to an incrementally higher temperature. In a further alternative, the branches can alternate between increasing and decreasing temperatures.

(19) In the illustrated apparatus for temperature regulation, co-current flows can also be used.

(20) Referring now to FIG. 2, there is shown a process apparatus 201 comprising a jacketed vessel 202 encased by a shell 203. The shell 203 contains fluid which acts as global temperature regulation means. The shell 203 has fins (not shown) attached to its internal surface to promote local turbulence in order to enhance the efficiency of cooling or heating. Thermal isolation laggings (not shown) can be applied to the shell 103 to maximise the cooling or heating effect. A series of branches 204 connected to a temperature manifold 205 form a local temperature regulation means. Control valves 209 are place at points on the local temperature regulation means to divert heating or cooling as the user desires. The arrows superposed on the local temperature regulation means indicate the counter-current direction of flow for a coolant or heating fluid. The local temperature regulation means is equipped with a cooling/heating tank 214 and a pump 215. At one end of the vessel 202 there is a piston 210 to impart oscillatory motion to the contents of the vessel 202.

(21) The vessel 202 has a plurality of substantially parallel tubular members 206 joined together by U-bends 207 in a serpentine fashion. The vessel 202 contains baffles 208, which are arranged in cells. The number of cells, tubular members and U-bends is not limited. Attached to the vessel 202 at the reactant feed end are a feed tank 212 and a pump 213. Between the pump 213 and the vessel 202 there is positioned a flow meter 217 and an input control valve 218. A number of inlet and outlet ports 211 are situated along the length of the vessel 202, the ports being designed to allow species, seeds or any other additive to be added and/or removed from the vessel 202.

(22) At a point in the vessel 202 there is provided a Y-junction 220. After the Y-junction the vessel 202 splits into separate tubular members 206a and 206b. The contents of the two separate tubular members 206a and 206b are separate and can be heated/cooled, added to/subtracted from, or otherwise adjusted probed or treated independently. The product collection end of tubular members 206a and 206b are connected to centrifugal separators 216a and 216b respectively.

(23) Whilst in the example given the vessel is split using a Y-junction or Y-connector, it will be appreciated that many different manifold-type arrangements such as T-pieces, cross-pieces or multiple inlet and/or outlet manifolds can be used. For example, the tubular members can comprise at least one manifold adapted to divert the flow of the contents of the tubular member along more than one flowpath.

(24) The apparatus as described comprises a vessel adapted to receive and discharge fluids, and having a series of tubular members, each defining a discrete process zone, arranged and operatively connected in a flow system to form at least one continuous fluid flow path having an inlet and an outlet, wherein mixing means is provided within the flow path, and wherein each process zone has temperature regulating means juxtaposed thereto for effecting temperature control therein.

(25) With reference again to FIG. 1, in a controlled crystallisation process, a supersaturated solution at a given temperature, say 80 C. from the tank 112 is pumped, via an inlet, into the vessel 102 using a pump 113, flow meter 117 and the input control valve 118. The cooling medium (either water or coolant), at 5 C., is pumped, via a first inlet, into the shell 103 from the cooling/heating tank 114 using a pump 115 and control valves 109, counter-current to the solution flow.

(26) The cooling medium leaves the vessel 102 from the final outlet and returns to the cooling/heating tank 114. By controlling both the global flow rate from the first inlet together with the local flow rates from subsequent inlets, a predetermined temperature decreases, say 10 C. per meter from left to right, can be achieved and maintained. As such, the temperature of the contents of the vessel can be controlled in terms of degrees Centigrade per meter ( C./m), or degrees Centigrade per minute ( C./min). This confers to the user a much greater degree of controllability over the physical and chemical properties of the products obtained from the vessel.

(27) Still referring to FIG. 1, the solution cools as it flows from left to right along the vessel 102, and the product crystallises and is suspended in solution until it comes leaves the vessel via an outlet into a centrifugal separator 116. As the temperature decrease is controlled incrementally, the initial temperature, the final temperature and the rate of cooling are constant for the whole of the crystallisation process. Consequently, the crystallisation product is of consistent size and shape.

(28) The apparatus in this example provides a controlled and consistent cooling of the solution over a manageable time period. As such, the products in the vessel are always under the control of the apparatus operator. In contrast, when a product is cooled in a batch reactor, the process can take many hours or days, and the temperature of the product at different parts of the batch reactor is often variable. Furthermore, the bulk cooling gradient can be inconsistent and, importantly, cannot be directly controlled.

(29) For example, with reference to FIG. 3, there is shown a graph that illustrates a linear cooling profile achieved with the apparatus of the present invention. In this example a solution is cooled from 90 C. to 10 C. at a constant rate of 2 C. per minute to obtain linear cooling over a 40 minute period.

(30) The apparatus facilitates a method for continuously controlling a process applied to an at least partially fluid media according to a predetermined regime. The method as described involves the steps of forming a continuous flow system for fluid media from a plurality of tubular members operatively connected to permit fluid communication therethrough. Each tubular member contains baffles, which act as mixing means when combined with fluid flow or oscillation, and provides a discrete process zone. The apparatus also has branches which provide temperature regulating means juxtaposed to each tubular member. By introducing fluid media to the flow system and controlling the temperature regulating means, it is possible to independently or collectively control the temperature of the discrete process zones.

(31) The temperatures of the discrete process zones of the continuous flow system can be adjusted such that the rate of temperature change of the fluid media is consistent or inconsistent along the tubular members.

(32) The temperatures of the discrete process zones of the continuous flow system can be adjusted such that the rate of temperature change of the fluid media is linear or non-linear along the tubular members.

(33) Various modifications can be made to the method. For example, a fixed starting and finishing temperature can be set to predetermined constant values, and/or the process conditions can be adjusted by introducing or extracting media as necessary.

(34) In the case of crystallisation, crystalline solids can be selectively precipitated by, for example, adding crystallisation seeds. The crystallisation of only one enantiomer from a racemic mixture can be promoted, and collected using a filter. The opposite enantiomer can also be crystallised and collected. The crystallisation and collection of the two opposite enantiomers can be alternated between the two opposite enantiomers, or the crystallisation and collection of the two opposite enantiomers can be simultaneous.

(35) Having accurate control over the temperature of the products in the vessel facilitates selective crystallisation. For example, by carefully selecting different controlled rates of cooling, different sizes of crystal can be precipitated. In addition, by carefully selecting different starting temperatures and different finishing temperatures, crystals with different morphologies can be selectively grown. The filters are used to selectively remove certain sizes or shapes of crystal, whilst allowing the remainder of the solution to progress through the vessel.

(36) For example, with reference to FIGS. 4a and 4b there is illustrated different crystal morphologies obtained using different cooling rates. FIG. 4a illustrates -crystals that were obtained using the apparatus of the present invention and a constant cooling rate of 0.6 C. per minute applied from the start of the vessel, for the duration that a reaction mixture is present in a vessel.

(37) In contrast, FIG. 4b illustrates -crystals obtained using the apparatus of the present invention and a cooling rate of 1.3 C. per minute as applied from half way along the vessel. Therefore, it is clear that the apparatus of the present invention can be used to alter crystal morphology.

(38) The local temperature regulation allows controllable and variable flows (including optionally zero flow) of cooling or heating medium so that the temperature of the individual branches can be different from, or the same as, each other and can be controlled independently or collectively.

(39) Whilst in this example the means for controlling the temperature of the vessel is a jacketed tubular device with both global and local temperature regulation means as described, it will be understood that other suitable means for controlling temperature could be used. Typically such means will be modular in construction which allows the modules to be independently controlled. In this manner, the temperature of discrete zones of the vessel and its contents can be independently controlled.

(40) In an alternative embodiment, individual temperature regulators, not connected by a manifold, can be attached to the limbs of the tubular member. These individually control the temperature of the limbs, and can be set to any desired temperature. Also, the means for regulating temperature can take the form of a heat exchanger, so that the vessel can be submerged in the heat exchanger, thus minimising the loss of energy and making the apparatus more efficient. A further alternative means for regulating temperature is the inclusion of cold fingers and/or heating elements inside the tubular members of the vessel. In a still further alternative the baffles can be attached to connecting rods, and this combination can provide means for regulating temperature, by cooling or heating the contents of the vessel.

(41) Use of the apparatus of FIG. 1 will now be described with reference to the pasteurisation of milk.

(42) Prior to the introduction of raw milk, the heating medium (either water or oil), say 85 C. is pumped into the shell 103 surrounding the vessel 102 from the cooling/heating tank 114 via a first inlet, and leaves the shell 103 from a final output, whereon it returns to the cooling/heating tank. The process carries on until all temperature measurements along the vessel 102 show an identical reading. Raw milk from tank 112, at 15 C., is then pumped into the vessel 102 via an inlet. Depending on the required pasteurisation time, the raw milk flows along the vessel 102 from left to right and is pasteurised along the flow path, before it exits the vessel 102, via an outlet, into bottles, cans, cartons, transportation vehicles or storage tanks.

(43) Throughout the process described, the contents of the vessel 102 are mixed by oscillation via the piston 110. In the above example, a constant temperature regulation is required. Should a variable temperature regulation be needed, the local temperature regulation means can be adjusted to provide this.

(44) Use of the apparatus of FIG. 1 will now be described with reference to a distillation process.

(45) Prior to the introduction into the vessel 102 of a mix of liquids with different boiling points, or a liquid containing different fractions of boiling points, a heating medium of oil or steam at approximately 200 C. is pumped into from the heating tank 114 to the shell 103 surrounding the vessel 102. The heating medium is pumped into the shell 103 via a first inlet, and leaves the shell 103 from a final output, whereon it returns to the heating tank 114.

(46) Whilst global heating is applied to the vessel 102, local cooling is applied by reducing the temperature of discrete zones of the tubular members 106, by say 30 C. per predetermined length. In this way, an incremental temperature reduction along the flowpath is achieved. Condensers (not shown) are connected to strategic ports 111 along the length of the vessel 102 to collect different vapour fractions at different points whilst maintaining a continuous flow, thereby achieving continuous distillation.

(47) Referring now to FIG. 2, the vessel 202 forks in the shape of a Y (via a Y-branch 220) in the direction of flow, such that the material flowing through the tubular member 202 may flow along both forks 206a and 206b. In one use of the apparatus, downstream from the Y-branch 220, the contents of the forks 206a and 206b are seeded with materials that promote the crystallisation of opposite enantiomers. The opposite enantiomers, which crystallise separately in the two forks 206a and 206b, are then collected simultaneously via centrifugal devices 216a and 216b.

(48) This accurate and selective control of crystal growth, and simultaneous crystal separation, cannot be achieved on any commercial scale in typical batch reactors or the like.

(49) It will also be apparent that the apparatus of present invention can be used such that the rate of cooling or heating, and the initial and final temperatures, can be deliberately deviated to promote the growth of crystals of different sizes and different morphologies.

(50) As described earlier, the crystalline product is of a solid form, hence solids are suspended and transported along the vessel, although the contents of the vessel retain at least some fluid character. The uniform and enhanced mixing, in particular, plug flow characteristics achieved in this type of apparatus, can give rise to effective solid suspensions and effective conveyance of said suspension in the baffled tubular members, with or without oscillation.

(51) Referring once more to FIG. 2, selective distillation can be achieved as follows. A mix of liquids with different boiling points or a liquid containing fractions with different boiling points in the feed tank 212 is pumped through the vessel 202, while the heating medium of oil or steam, at 80 C. is pumped from the heating tank 214 into the shell 203 surrounding the vessel 202. The heating medium is added via a first inlet and leaves the shell 203 from a final output, whereon it returns to the heating tank 214.

(52) The method allows for the selective distillation of at least one liquid, and can afford the diversion of the flow of a fluid media along disparate tubular members of the continuous flow system by way of a manifold.

(53) Once a steady-state is reached, local heating effects are applied to tubular members 106a and 106b such that two different temperature increases are achieved simultaneously thereby affording the selective collection of two different vapours. Such a process cannot be carried out using conventional apparatus.

(54) In all of the above cases, the apparatus used provides for effective and accurate temperature regulation in combination with efficient mixing and dispersion of the vessel contents, to provide and control the type, shape, size and homogeneity of the process being carried out, and of the products that are made. The temperature regulation can be linear, non-linear, or a combination of linear and non-linear.

(55) A process apparatus with more efficient, uniform mixing, plug flow characteristics and much better heat transfer rates avoids the need for scale up and allow crystallisers to be much smaller (by factor of 30-40 fold). This reduces capital costs, space and other overhead requirements and the smaller plant has lower operating costs. Additionally, the plant is skid-mounted and portable.

(56) Improvements and modifications may be incorporated herein without deviating from the scope of the invention.