WO2006010490A1

WO2006010490A1 - Device and method for continuously carrying out chemical processes

Info

Publication number: WO2006010490A1
Application number: PCT/EP2005/007699
Authority: WO
Inventors: Wolfgang Ehrfeld; Thomas Schwank
Original assignee: Ehrfeld Mikrotechnik Bts Gmbh
Priority date: 2004-07-22
Filing date: 2005-07-15
Publication date: 2006-02-02
Also published as: EP1776183A1; DE102004035462A1

Abstract

The invention relates to a device for continuously carrying out chemical processes and to a corresponding method. Said device and method are used to obtain a narrow residence time distribution for the reaction medium and to set a defined temperature profile in the reaction chamber.

Description

Apparatus and method for the continuous performance of chemical processes

The invention relates to a device for the continuous implementation of chemical processes and a corresponding method, with which a narrow residence time distribution for the Reak¬ tion medium is achieved and at the same time a defined temperature profile can be set in the reaction chamber.

Chemical reactions can be carried out particularly advantageously with the aid of microreaction technology, in which components are used for the basic operation of the process engineering and the reactions whose smallest characteristic dimensions are typically in the range of a few micrometers to a few millimeters. The smallest characteristic dimensions of the fluid guide are preferably below 1000 .mu.m, more preferably below 500 microns.

Due to the small dimensions compared to the standard components of chemical engineering, mixing operations can be extremely accelerated and the heat transfer in heat exchangers can be drastically increased, as for example in the article by W. Ehrfeld, V. Hessel and V. Haverkamp: Microreactors, Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, Wiley-VCH, 1999. In conjunction with the usually continuous mode of operation of microreaction technology apparatuses, it is thereby possible to very precisely control chemical processes on a timescale in the millisecond to seconds range. Due to the small dimensions but also the throughput is limited, so that for the production of technically relevant quantities, if necessary, a larger number of microreaction systems, each containing the corresponding procedural basic elements, must be connected in parallel (numbering-up principle).

An economically more advantageous solution for production is simply to increase the number of microstructures relevant to the process. In this process, a large number of microstructure elements to be operated in parallel are built up or incorporated into a sufficiently large base body or substrate, and this base body is installed in a correspondingly larger housing (equaling-up principle). This approach is followed, for example, in a high mass flow mixer in which tens of thousands of microstructures are machined into a square plate about 10 cm in side and 0.3 mm thick, all in parallel with the fluid streams to be mixed operated (DE 202 18 972 Ul). This makes it possible to achieve volume flows of a few 1000 L / h at low pressure losses of a few bar with aqueous media. Also known are micro heat exchangers, which consist of stacked, provided with many microchannels and welded together thin plates. The basic geometry of such heat exchangers is approximately cubic, with a Edge length of, for example, 3 cm heat transfer performance in the range of 100 kW can be achieved (K. Schubert, W. Beer, J. Brandner, M. Fichtner, C. Franz, G. Linder 2nd International Conference on Microreaction Technology, 9.-12 March 1998, New Orleans, USA, Tropical Conference Preprints, ISBN 0-8169-9945-7, pp. 88-95).

So far, there are such microreaction devices that are designed for operation at high flow rates, but only as individual components that do not have suitable fluidic interfaces with each other. Thus, the individual components are usually connected via flange connections, often even with intermediate connecting tubes miteinender containing shocks, abrupt cross-sectional changes or deflections. Likewise, such mold elements are often found in the flow guides of the inlet and outlet channels of the individual components. These shaped elements lead, as well as longer laminar (Re «2300) or uncontrollably turbulent (Re» 2300) flowed pipe sections, to an undesirable widening of the residence time spectrum within a microreaction system, ie different volume elements of the flowing through the system process medium have different residence times in the individual volume elements of the microreaction system, which of course runs counter to the advantages of good process control within the microstructures. In addition to broadening the residence time spectrum often proves to be the long residence time in the connection volumes between the microstructures, within which no control of the process parameters is possible, as disadvantageous. In addition, some ^'components are like the above-mentioned high-performance micro heat exchanger itself already not ideal because of their long and very narrow channels for use in micro-reaction systems for high throughputs. On the one hand, the laminar flow, which practically exists over the entire channel length, leads to a relatively broad residence time distribution which, moreover, is broadened by volume flow inhomogeneities between the individual channels. Such significant differences in the volume flow between the individual channels of a parallel bundle are due to the natural manufacturing tolerances in the channel dimensions, which in turn have a given pressure loss in the fourth power on the respective volume flow, practically unavoidable. On the other hand, such bundles of long, narrow channels are highly sensitive to contamination, since even small particles in the reaction medium can clog these channels.

For the construction of reaction systems, which can be operated continuously with high efficiency on an industrial scale, the components available so far are therefore only suitable to a limited extent. A simple connection herewith to a reaction system consisting of mixers, reaction chambers and heat exchangers would neither allow to specify a defined course of the reaction temperature in the chemical conversion process nor a defined one Set reaction time. The advantages of the intensification of heat and mass transfer processes, which are characteristic of microreaction technology, can ultimately not be fully exploited. The disadvantage here is mainly the fact that in such an interconnection fluidly non-matched system components different volume elements of the process medium remain different lengths in the reaction chamber. As a rule, this has the consequence that, for volume elements which remain only comparatively short in the reaction space, no complete chemical reaction has yet taken place, while in other volume elements, which remain very long in the reaction space, for example in dead water zones, undesired secondary reactions can occur. Optimum values for the conversion, the selectivity and the yield of the reaction can hardly be achieved in this way.

The object of the present invention is to find a device and a corresponding method with which chemical reactions on an industrial scale using microreaction system components can be carried out so that a narrow residence time distribution can be achieved at a defined temperature profile in the reaction space.

The object is achieved by a device according to claim 1 and the claims back thereon and a corresponding method.

The device according to the invention for carrying out chemical reactions in a continuous process comprises an arrangement of components of the microreaction technique for reactions and basic operations of process engineering, as reaction spaces and / or for process analysis, which are designed for high mass flows. Components according to the invention are designed for a volume flow of preferably more than 25 l / h or a mass flow of preferably more than 25 kg / h, more preferably of more than 200 l / h or 200 kg / h.

The flowed through by the process medium or the reaction mixture components consist of a plurality mikrotechnischer preferably similar and transverse to the main flow direction preferably equidistantly arranged functional elements, which are installed in rohrförrnige housing and are preferably flowed through in parallel, wherein the housing each with approximately the same flow cross-sectional shapes and in particular in the area Fluidic interfaces also have approximately the same flow cross-sections and are directly connected. There are therefore no connecting tubes between the individual housings, apart from such tubular spacers with likewise approximately the same flow cross-sectional shapes, which are specifically installed to increase the residence time between microreaction modules. The cross-sectional shapes of the housing can be circular, oval rectangular or polygonal executed with rounded, wherein play an important role in determining the shape, especially production-related aspects with regard to the microstructured functional elements. Within the components of the flow cross section outside of the microstructured functional elements varies continuously, with taper wall angles to the flow axis preferably less than 40 °, with extensions preferably less than 20 °, more preferably be kept smaller than 7 °.

As a result of the multiplicity of microstructured functional elements (equal-up principle) connected in parallel in a section or in a component or module, the flowing reaction mixture, when passing through such a component, is divided into a plurality (between 10 ¹ and 10 10 ⁾ over a relatively short distance ⁶ ) split smaller partial flows, which unite again immediately after passing through the microstructured functional elements to a total current. Since the velocity profiles of the partial flows compensate quickly, the flow profile of a piston flow (plug flow) is established in the total flow, which in turn leads to a narrow residence time distribution. It is precisely this setting of a piston flow within the connecting sections between the microstructured functional elements that constitutes an essential conceptual component of the device according to the invention.

The residence time distribution within the substreams also depends on their velocity profiles. If the flow paths through the microstructured functional elements are very short, only trapezoidal start-up flows are formed which, due to the small dimensions of the partial flows within the microstructured functional elements, also have only short diffusion paths. The associated residence time distribution is therefore much narrower than in the case of a formed laminar flow, which is known to have a parabolic velocity profile with correspondingly different velocities of the volume elements at the edge or in the middle of the flow. For this reason, as well as to reduce the risk of clogging, such microstructured functional elements are preferred, within which the flow paths are at most as long, particularly preferably at most half as long as the hydraulic diameter of the flow cross section in the housing in the region of the microstructure.

Moreover, since the cross-sectional shapes of the housings through which the reaction medium flows are approximately equal and the individual pipe sections smoothly adjoin one another without steps or abrupt changes in the cross-sectional shape, separation of the flow from the inner wall of the housing is avoided. This dead water zones with long residence times for parts of the reaction mixture, which would broaden the residence time, largely excluded. Through the device according to the invention, therefore, a flow distribution is achieved in the entire reaction system, which results in largely identical residence times for all voids. menelemente of the reaction mixture in the volume flowed through, ie, a total of a vorteil¬ tight close residence time distribution ensures the reaction mixture.

In this way, a tubular reaction system consisting of individual sections is formed with microstructured functional elements following one another in the flow direction, these functional elements forming components (modules) of the reaction system together with the respective housing. Apart from the first component of the system, which is preferably designed as a mixer for the preparation of the reaction mixture, the other components are designed as units which are preferably straight, that is, from the reaction mixture. without changing the main flow direction at the outlet opposite the inlet, to be flowed through. These may be components for carrying out basic operations of process engineering, for example for exchanging heat, adding further substances or separating, or reaction spaces containing, for example, heterogeneous catalysts. Other components can be used for process analysis.

The reaction space for the chemical reaction in the reaction system according to the invention is formed by the entire volume flowed through or parts of this volume, wherein the length of the residence time is determined by the size of the volume and the volume or mass flow of Reak¬ tion system. Depending on the required residence time, this can be predetermined by a corresponding adjustment of this flow or by a change in the volume, wherein it is particularly cost-effective to provide individual tube sections of suitable length for setting this volume or the residence time between the microstructured functional elements Insert components as dwell lines. Since there is a piston flow in these for a certain distance, which may be a large fraction up to a few multiples of the hydraulic diameter of the main flow cross section depending on the flow conditions, a narrow residence time distribution is maintained within these pipe sections.

For longer dwell distances, it depends on the flow conditions (Reynolds number) to maintain or readjust the piston flow, ie for suppressing a laminar flow profile or a turbulent flow with strong backmixing expedient to install in the pipe sections perpendicular to the main flow direction aligned plates with provided a plurality of openings or channels and are inexpensive to manufacture. Again, as already stated, the desired profile of a piston flow is realized by combining numerous small partial flows. Also in this case, the distance between successive hole / channel plates is preferably at least eight times the hole or channel spacing on the respective upstream plate, but at most three times, preferably the simple hydraulic diameter of the Main flow cross-section between the plates. The arrangement may also differ from the preferred arrangement perpendicular to the main flow direction. The plates may also be corrugated, folded or otherwise multi-dimensionally structured. The smallest dimension of the openings is preferably at most one tenth of the total cross section of the main flow. The number of openings is between 10 ¹ and 10 ⁶ , preferably between 100 and 1000. The openings leave a total of at least 10% and preferably at most 50% of the cross section of the main flow free.

If, for reasons of process control, on the other hand the smallest possible dwell volume between successive microstructured functional elements is required or advantageous, then the freely traversed length between these functional elements should nevertheless amount to at least approximately six times the greatest lateral spacing of adjacent outflow openings of the respectively upstream microstructured functional element in order to obtain from Overlay the sub-beams again to produce a sufficiently smooth Kolbeströmungsprofil.

In order to meet the different requirements of various chemical reactions with a manageable number of components, the components with microstructured functional elements installed in tubular housings and the pipe sections serving as retention zones are preferably designed as modules with defined lengths according to a predetermined grid dimension. This makes it possible to exchange modules with different Funktions¬ elements, but the same pitch against each other and to change the order of the modules or the configuration of the reaction system with minimal effort. With a kit of modules, the user can optionally flexibly set up completely different reaction systems after the end of use, without incurring additional investment costs. A typical pitch for the length of the module is a quarter of the inner diameter of circular cylindrical cross section and the width of square cross section. For modules designed for a flow rate of 1,000 L / h for aqueous reaction media, for example, a pitch of 25 mm is selected.

The connection of the modules can easily be done via flanges. However, a particularly cost-effective and flexible solution also consists in the possibility of carrying out the modules only in the form of pipe sections and compressing them after the insertion of sealing elements by means of a clamping system which can extend over the entire length of the tubular reaction system. For this purpose, hydraulic presses can be used, preferably those with pressures below 250 bar. With sufficient pressure, metallic seals can also be used. In each case exchangeable modules are used which, for the fluidic connection with one another, preferably have a maximum of up to three different interfaces and particularly preferably only one uniform interface. Different interfaces or cross sections are used, for example, if, for example, the total volume flow within a module is markedly increased by the admixing of further fluids or by gas evolution. With a constant cross-section naturally increases the flow velocity by a larger volume flow, which can be undesirable and can be compensated by a larger cross-section.

An essential characteristic of any uniform interface is that the flow cross-sections meeting each other in the region of the interfaces are approximately equal, preferably exactly the same. This is also evident from the stated requirement that the modules are connected to each other without paragraphs or abrupt change of the cross-sectional shape.

Preferably, the cross-sections through which the reaction medium flows are approximately the same on the inflow and outflow sides of the housings, and the individual tube sections can be smoothly connected to one another without steps or abrupt changes in the cross-sectional shape.

In some cases, due to various physical, chemical, fluidic or other mechanisms with special modules, the shape of the flow cross-section of the other modules and the interfaces can not be taken over the entire length. This can, for example, relate to photochemical processes if the incident light is already absorbed by the reaction medium over a very short distance. In this case, it is necessary to design the reaction space as a thin layer bounded by walls or windows with a correspondingly large surface area. The same applies to fixed-bed catalysts with high flow resistance per unit area flowed through, in which the cross-sectional area must be increased to avoid inadmissible pressure losses. An increase in the cross-sectional area may also be expedient for dwell lines if relatively long residence times or corresponding residence volumes are necessary.

In a further development of the device according to the invention, it is therefore intended to gradually adapt such geometries to the cross-sectional shapes of the directly adjacent components or modules by suitably shaped transition regions. In the case of a circular cross-section of the fixed-bed catalyst, such transitional regions are embodied, for example, in the form of a slender cone. This ensures that there is no separation of the flow from the inner wall of the housing and prevents the formation of dead-water zones, which inevitably form during abrupt changes in the flow cross-section and detrimentally broadening the residence time distribution. The necessary length of such transition regions can be significantly shortened, for example, by the incorporation of plates oriented perpendicularly to the flow and provided with small openings, without the residence time distribution being unduly broadened.

In the following, individual components or modules of the inventive devices are described in more detail. Common to these components is that they are flowed through in the reaction system so that a large number of small partial flows are generated in the areas provided with microstructures, these partial streams then reunite into a main stream, which is guided without flow separation on the housing wall. Thus, the device according to the invention has the advantage of a piston flow with a low residence time distribution within the flow paths between the microstructured functional units.

A corresponding mixer for admixing further substances can advantageously be designed such that a plurality of tubes provided with lateral openings or comparable structural elements are arranged as supply lines perpendicularly (transversely) to the flow direction. In one embodiment of the invention, the leads are arranged in one plane or in several superimposed planes. The substances in question are introduced from the outside into the tubes and fed via the lateral openings of the main stream. As it flows through the mixing zone formed by the tubes, the main flow is split into many parallel, narrow lamellar partial flows, into which the partial streams of the further substances flow laterally, so that rapid and uniform mixing is ensured. It is readily possible to introduce different substances into adjacent tubes. The arrangement can consist of straight tubes aligned in parallel or also of tube layers arranged one above the other, the tubes being offset from one another or being rotated by a certain angle with respect to the tube axes. In addition to parallel straight tubes, it is of course also possible to use other arrangements, for example geometries in the form of a spiral or a helix. Likewise, it may be advantageous to use leads with other cross-sectional shapes instead of tubes with a circular cross-section.

As heat exchangers or heat exchangers for the devices according to the invention, according to the abovementioned boundary conditions, arrangements are suitable in which tubes aligned perpendicular to the flow are installed in the housing through which the reaction mixture flows, which are flowed through by a heat transfer medium or electrically heated. To increase the heat transfer, such tubes are expediently arranged offset in several directions in the direction of the main flow. For heat exchanger modules designed for aqueous reaction media and flow rates in the range of 1000 L / h and one. Housing cross-sectional area of about 100 cm ² , are advantageously used tubes with an outer diameter in the range of one millimeter, which are arranged at a distance of less than one millimeter. Such high-performance micro heat exchangers achieve transmission powers of a few 10 kW, have low pressure losses and, moreover, are easy to clean.

In another type of high-performance micro heat exchanger, plate-shaped bodies are installed in the housing through which the reaction mixture flows, which are electrically heated or flowed through as a hollow body by a heat transfer medium. Such microplate heat exchangers typically have sub-millimeter plate gaps, and the plates can be easily disassembled and cleaned. As with the microtube bundle heat exchanger described above, heat transfer capacities of a few 10 kW are achieved here as well, given corresponding boundary conditions.

The micro-heat exchangers described here can be used in a simple manner for catalytic reactions by applying catalytically active layers to the tubes or plates of the micro-heat exchangers. A significant advantage of such catalyst modules is that the temperature of the catalytically active surface can be accurately adjusted. At the same time, it is ensured that the temperature of the reaction mixture can be precisely adjusted by the high heat transfer performance of such arrangements, which has a positive effect on the yield and selectivity of the reaction.

In another catalyst module catalytically active powder or catalyst pellets are enclosed in the interstices between the tubes or plates of the micro heat exchanger according to the invention and through perforated plates or sieves above and below the tubes or plates and of perforated plates or sieves, heat exchanger tubes or Plates and catalyst material formed assembly is installed in a module housing and flows through the reaction mixture. Preferably, these are installed perpendicular to the main flow direction in the housing of a module or a component. Such an arrangement has the advantage that catalysts can be used without problems as commercially available delivery form as a fixed bed and at sufficiently high flow rates as a fluidized bed. To achieve a sufficiently large area through which the reaction mixture flows or to reduce the flow resistance, the perforated plates or sieves may, for example, also be corrugated or cone-shaped. It is likewise possible to use appropriately shaped stable sintered bodies of catalytically active material instead of beds of loose powders or pellets. The properties of the catalyst modules described herein can be advantageously combined by introducing catalytically active powders or catalyst pellets into the interstices between the tubes or plates of the micro heat exchangers and trapping them through perforated plates or sieves above and below the tubes or plates. The arrangement of perforated plates or sieves, heat exchanger tubes or plates and catalyst material is installed in a module housing and the reaction mixture flows through it.

Moreover, it is possible to incorporate in such arrangements instead of catalyst materials also Schüt¬ lines of other functional materials with which special substances, beispiels¬, by absorption or adsorption, can be removed from the reaction mixture.

The possibilities for targeted cooling or heating of such functional materials can be advantageously used in such a way that the absorption or Adsorptions¬ effects can be enhanced by cooling, while released the detained substances by heating again and the absorption or adsorption be regenerated again can. A corresponding regeneration or activation can of course also be carried out with catalyst materials, it being possible where appropriate for the reaction mixture to be replaced by a suitable regeneration medium for this purpose.

In the following, methods according to the invention which are carried out using the devices described above and the underlying considerations are explained in more detail.

The process for carrying out chemical reactions in a continuous process using an arrangement of elements of the microreaction technique designed for high mass flows for reactions and basic operations of process engineering is therefore as follows

Thought: The flowing process medium is guided in a tubular arrangement so that it is split when flowing through the microtechnical functional elements in a plurality of small streams and these streams are then merged into a total stream, the processes of splitting and merging multiple, preferably at least three times, more preferably at least four to five times be repeated. According to this procedure is characterized by the sequence of parallel small

Partial streams with short diffusion lengths and the formation of piston-shaped Strömungsprofϊle achieved in the union of the partial streams total flow distribution in the reaction system, in which the individual volume elements of the reaction mixture approximately the same length in

Reaction system remain, so a narrow residence time distribution is achieved.

In a further development of the method, in which micro-functional functional elements generate a large number of small partial flows and repeatedly repeats them to an overall be merged stream, at a given throughput cost-effective adjustment especially longer residence times is possible. For this purpose, the volumes between the respective components provided with microtechnical functional elements and the total volume of the reaction space are correspondingly increased by dwell lengths in the form of tubular sections, optionally with increased cross-section and in conjunction with a suitably designed transition region, between these components with microstructured functional elements be introduced.

In many reactions, the decisive factor for selectivity, conversion and yield is a defined temperature profile in the temporal and spatial sequence of the chemical reaction process. By a suitable sequence of components, e.g. a sequence of heat exchangers and dwell lines or modules with micro heat exchangers, this temperature profile in the flowing reaction mixture along the flow direction can be set in the desired manner. If, for example, the heat produced during the reaction is very high in the case of an exothermic process at the beginning of the reaction, it is initially possible to insert only short pipe sections as dwell lines between individual heat exchanger components or to use the volumes of these components as reaction volumes. Further downstream, if a corresponding part of the reaction mixture has already been reacted and the local formation of heat of reaction is correspondingly lower, the length of the pipe sections serving as retention zones for the residence time can correspondingly be increased and thus an approximately constant temperature profile in the flowing reaction mixture.

This situation also applies correspondingly to endothermic reactions in which heat is consumed in the reaction mixture and a heat input is required to adjust the reaction temperature. Of course, the possibility described here for adjusting the temperature profile along the main flow direction is not only suitable for achieving a constant temperature, but other temperature profiles can also be realized, for example with an increase or decrease in the temperature at the beginning or end of the reaction.

The devices of the invention and the corresponding methods can be used not only for single-stage, but also for multi-stage reactions. In this case, for example, one or more further substances are admixed to the flowing reaction mixture with the aid of a flow-through micromixer and then reacted.

Also existing in the flowing reaction mixture substances can be implemented by means of a passage through components provided with catalysts (catalyst modules). After a first reaction in further upstream regions of the reaction system, a subsequent reaction with previously formed reaction products can thus be initiated become. The introduced into the modules catalyst or other functional materials can then be changed or regenerated by cooling or heating in their properties.

Furthermore, it is possible to initiate a subsequent reaction by an additional energy supply in the flowing reaction mixture or in the already formed reaction products.

This can be done, for example, by an increase in temperature in a component provided with heating elements or by components which cause, for example, the irradiation of electromagnetic radiation (eg of light or microwaves), the action of ultrasound, the passage of electrical current or the excitation of a plasma , It is essential that the components used can be flowed through by the reaction mixture.

Of particular importance for the efficient implementation of continuous reaction processes is the monitoring, control and regulation of the process. The modules of the reaction system can therefore be equipped with appropriate sensors with which, for example, the temperature of the reaction medium is measured locally and adjusted to the desired value by changing the temperature and / or the throughput of the heat exchanger medium in the heat exchanger module in the required manner. Also important is process analytics, for which modules for continuous optical analysis are preferably used, with which, for example, the optical absorption of a specific constituent of the process medium in a specific spectral range is measured. In other cases, the analysis takes place via the removal of samples for which special sampling valves are attached to corresponding modules.

Embodiments of the invention are illustrated in the drawings and will be described in detail below.

Show it:

Figure 1: Schematic representation of a constructed from modules reaction system for carrying out continuous reactions with high mass flows

Figure 2: Schematic representation of the development of the flow profiles when flowing through a module with a plurality of parallel connected mikrotechnischer Funktionsele¬ elements

FIG. 3: Insertion of dwell lines with and without perforated plates to increase the reaction volume or the residence time and to set the reaction temperature

Figure 4: Modular design with clamping system FIG. 5: Micromixer for feeding further substances into the reaction mixture stream

FIG. 6: catalyst modules

Figure 7: transition areas for the alignment of the cross-sectional shape of narrow and wide functional areas to the standard cross-sectional shape of adjacent housing

FIG. 1 shows a schematic representation of a reaction system constructed from modular components (modules) 1 for carrying out continuous reactions with high mass flows. In the modules ^• 1 a plurality of parallel connected mikrotechnischer Funktions¬ elements 2 for the implementation of reactions and basic operations of process engineering is installed. The housings 3 of the modules are of tubular design and each have the same flow cross-sectional shapes with respect to the inner wall of the housings. The housings are interconnected by flanges 4 with gaskets (not shown) therebetween. The constituents A and B of the reaction mixture C are first fed via supply lines 5 to a fluid distributor system 6 and introduced into a multiplicity of parallel microtechnical mixing elements 7, with which a multiplicity of uniformly composed substreams c of the reaction mixture are produced Combine total stream C of the reaction mixture. The reaction can take place partially or completely already directly in or after the microtechnical mixing elements or can be introduced into downstream microtechnical Funktions¬ elements 2a, 2b or 2c. However, these downstream functional elements can also serve the purpose of causing physical changes in state, for example a change in the temperature in heat exchangers, or be used for subsequent reactions in multi-stage processes. The respective changes of the reaction mixture stream or of the corresponding partial streams are indicated by the letters D and E or d and e, while F represents the product stream discharged from the reaction system.

FIG. 2 shows a schematic representation of the development of the flow profiles in the reaction mixture as it flows through a module 1 with a multiplicity of microtransport functional elements 2 connected in parallel. For example, a micro heat exchanger 8 with a bundle of tubes 9 oriented perpendicular to the flow direction is used, for reasons the overview increases the distances between the tubes and the number of tubes, which can be a few hundred, is greatly reduced. The velocity profile V 1 of the reaction mixture flowing towards the tube bundle initially corresponds to that of a piston flow, which has previously formed, as also described below, from the confluence of a multiplicity of small partial flows. As it enters the tube bundle, the velocity between the tubes increases, and when exiting, results in a profile V2 with a variety of high velocity regions. The narrow, lying between the tubes dead water zones act is based on the width of the residence time distribution only to a small extent, since between the areas with high speed due to the small transverse dimensions, a rapid mass transfer by diffusion takes place, which is also mostly supported by a convective mass transfer by secondary flows. By viscous and possibly also caused by turbulence speed compensation the profile V2 goes quickly into the profiles V3 and V4 and then in the profile V5 of a piston flow. For these, of course, the so-called Haft¬ condition, that is, the speed drops on the housing wall in a narrow Grenz¬ layer to zero.

FIG. 3 makes it clear how the residence time can be inexpensively extended for a given throughput and the temperature in the flowing reaction mixture can be set. Between the modules 1 provided with microtechnical functional elements 2, pipe sections are inserted as Ver¬ legerstrecken 10 whose length or volume is given according to the desired residence time. Even with long dwell distances or with the gradual transition to larger diameter, an approximately piston-shaped airfoil can be maintained by inserting plates 11 with a large number of small openings, as already explained above.

Over the length of the reaction path s, moreover, the temperature profile in the reaction mixture can be adjusted. The provided with microtechnical functional elements 2 modules 1 are each heat exchangers. Due to the high amount of heat of reaction released at the beginning of the reaction, the temperature initially rises correspondingly steeply from a value TQ to the temperature T _j , which is lowered again to the temperature T 2 when it passes through the heat exchanger module. Thereafter, there is again an increase to T ^, which is somewhat slower due to slightly lower amount of heat released per unit of track. In the subsequent dwell lines 10, their length is further increased in order to take account of the ever decreasing amount of heat and to keep the temperature within a certain oscillation range. At the end of the running distance, it may then be expedient to lower the temperature in a corresponding heat exchanger strongly to T3 in order to stop the reaction or to prevent undesired secondary reactions.

FIG. 4 shows a special, particularly installation-friendly embodiment of the reaction system in which the length of the individual modules 1 corresponds to an integer multiple of a given grid length R. The reaction space is sealed to the outside via sealing rings 12 between the modules. The modules 1 are pressed together via a clamping system, which consists essentially of an upper clamping plate 13 and a lower clamping plate 14 and threaded rods 15. Also incorporated in FIG. 4 are mixer modules 16 in which further connections for feeding in additional substances into the reaction system are provided for carrying out multistage reactions.

FIG. 5 shows a special micromixer which can be passed through by the original reaction mixture, more substances in the form of small partial streams g being fed to the reaction mixture stream E for carrying out multistage reactions. The mixer module 16 consists of the housing 3 as well as microtechnical functional elements 2, which are designed as provided with lateral openings 18 tubes 17 which are arranged perpendicular to the main flow direction of the reaction mixture stream E.

Figure 6 shows various embodiments of catalyst modules derived from heat exchanger assemblies. In the module 19, staggered tubes 21 are coated with porous material 22 in whose pores the catalytically active substance is introduced by known methods, for example by an impregnation process. In the module 20 (section of a structure extended transversely to the main flow direction), catalyst material 24 is introduced between the plate-shaped hollow bodies 23, which are flowed through by a heat transfer medium or else heated electrically. The typical distances between two hollow bodies are about 1 mm. Above and below the formed from the hollow bodies 23 and catalyst material 24 are provided with openings cover plates 25 are mounted. In another mode of operation, the catalyst material may be reactivated or, for example, an absorber material may be introduced instead of catalyst material.

FIG. 7 shows arrangements with components and modules in which the flow cross sections in the respective functional sections (indicated only schematically), which are provided with microtechnical functional elements, deviate from the cross-sectional shapes of the adjacent components, dwell routes or modules. In this case, transition areas are required by which the cross-sectional shape of the functional area is gradually adjusted to the cross-sectional shapes of the immediately adjacent modules, as shown schematically in Figure 7. If the cross-section of a functional region 26 is smaller than the standard cross-section of the housing, the transition takes place in a convergent supply channel 27, which may have a relatively short length, since there is usually no separation of the flow from the channel wall and thus not to dead water zones which would lead to a broadening of the residence time distribution. The divergent discharge channel 28, however, is designed to be substantially longer in order to keep the essential for the detachment angle between the Wendetangente the channel wall and the main flow direction sufficiently small. By inserting perforated plates 11, a separation can be suppressed and the transition of the housing cross-sections with a shorter divergent discharge channel 29 can be realized. If the cross-section of a functional area 30 is greater than the standard cross-section of the housings, then the transition takes place in a divergent supply duct 31 and a convergent discharge duct 32. To avoid separation of the flow from the duct wall, the divergent supply duct 31 should have a slender shape. By inserting perforated plates 11, the transition can also be realized with a shorter divergent supply channel 33. For functional areas which, for example, have a plate-like shape, that is wider in one direction and narrower in the other direction than the standard cross-section of the housings, corresponding criteria apply to the design of the transition areas.

A, B Components of the reaction mixture before the reaction

C reaction stream c partial streams of the reaction mixture

D, E Chemically or physically altered reaction mixture streams d, e Chemically or physically modified partial streams of the reaction mixture F Product stream f Partial streams of the product

G additionally fed component for multi-stage reactions g additionally fed partial streams for multi-stage reactions

H Temperature control medium R Screen length s Reaction distance

T temperature

V Velocity profile x Width or diameter of the tube 1 Modular components (modules) of the reaction system

2 microtechnical functional elements (operated in parallel)

3 housing of the modules

4 flange

5 Feed lines for constituents A and B of the reaction mixture 6 Fluid distribution system

7 Microtechnical mixing elements (operated in parallel)

8 micro heat exchanger

9 tubes of the micro heat exchanger

10 retention route 11 perforated plate

12 sealing ring 13 Upper clamping plate

14 Lower clamping plate

15 tension rods

16 mixer module

17 tubes of the mixer module

18 openings

19 Catalyst module with catalytically coated tubes

20 catalyst module with tempered catalyst material

21 tubes as catalyst support structure

22 Porous coating with catalytically active substandard

23 plate-shaped hollow body

24 catalyst material

25 cover plate

26 Functional area with narrow flow cross-section

27 Convergent supply channel

28 Divergent slim drainage channel

29 Divergent short discharge channel

30 Functional area with wide flow cross section

31 Divergent slender supply channel

32 Convergent discharge channel

33 Divergent Short Supply Channel

Claims

claims

1. An apparatus for carrying out chemical reactions in a continuous process, consisting of an arrangement of components of the microreaction technique for chemical reactions and basic operations of the process engineering, these components are designed for high mass flows, characterized in that a plurality of, preferably in parallel durchfiossenen , microstructured functional elements in rohrformige housing with preferably along the flow direction of approximately constant flow cross-sectional shape, are installed, wherein the housings of the components each have approximately equal flow cross sections for the total flow of the process medium and are directly connected to each other, so that consisting of individual sections, tubular reaction system is formed in the flow direction successive microtechnical functional elements.

2. Apparatus according to claim 1, characterized in that between the components provided with microstructured functional components pipe sections of predeterminable length for adjusting the volume or the residence time as dwell lines are installed, in which at certain intervals perpendicular to the main flow direction aligned plates having a plurality of preferably are installed approximately regularly arranged openings or channels.

3. Device according to claim 1 and / or 2, characterized in that components and modules whose flow cross section in the functional section of the cross-sectional shape of the adjacent components, dwell lines or modules deviates, transition areas are provided by the cross-sectional shape of the functional area gradually is matched to the cross-sectional shapes of the immediately adjacent modules.

4. Device according to one or more of claims 1 to 3, characterized in that the main flow direction of the total current at the output of each module is substantially the same as at its input.

5. Device according to one or more of claims 1 to 4, characterized in that the length of the flow paths of the partial streams within the microstructured

Functional units is smaller than the hydraulic diameter, preferably smaller than half the hydraulic diameter of the total flow cross-section in the starting plane of the respective microstructured functional units.

6. Device according to one or more of claims 1 to 5, characterized in that - with the exception of dwell modules - the arrival and Abströmvolumen each module is smaller than the filled by the respective microstructured functional units volume.

7. Device according to one or more of claims 1 to 6 _> characterized in that the respectively flowed through in parallel microtechnical functional units are arranged approximately uniformly distributed over the upstream total flow cross-section.

8. Device according to one or more of claims 1 to 7, characterized in that the free flow path between successive microstructured

Functional units and / or perforated / channel plates at least six times the distance of the Austrittsöffhungen the respective upstream microstructured functional unit and at most the largest hydraulic diameter of the main flow cross-section along this flow path corresponds.

9. A method for carrying out chemical reactions in a continuous process using an array of elements of microreaction technology for Reak¬ tions and basic operations of the process engineering, which are designed for high mass flows according to one or more of claims 1 to 8, characterized in that the flowing Process medium in a rohrförrnigen arrangement alternately when flowing through the microtechnical functional elements in a variety of small

Partial streams are split and these streams are then merged into a total stream, the operations of splitting and merging are repeated several times.

10. The method according to claim 9, characterized in that in the flowing reaction mixture during or after a first reaction when passing through another module by energy supply one or more subsequent reactions are triggered.