DE102024118229A1 - Device and method for improved coolant circulation in (micro-)structured reactors - Google Patents

Abstract

The present invention relates to devices and methods for improved coolant circulation in (micro-)structured reactors.

Description

All documents cited in the present application are incorporated in their entirety by reference.

The present invention relates to devices and methods for improved coolant circulation in (micro-)structured reactors.

State of the art:

In (micro)structured reactors, solid catalysts can be introduced as layers or as particle fillings. Such reactors are typically used for fast, high-energy reactions. The layered structure—alternating levels with flow of reaction medium and heat transfer medium—ensures efficient heat input and output, allowing the reaction to operate as close as possible to the target temperature. This is particularly effective when the reactor uses a coolant close to its boiling point on the cooling side, ensuring that at least a portion of the coolant evaporates as it passes through the reactor. This process utilizes the constant temperature of the coolant and the high heat transfer coefficient during phase transitions.

From an energy perspective and for reasons of isothermity within the reactor, preheating as close as possible to the boiling point of the coolant is advantageous. This is demonstrated, among other things, in US2013/0165536 A1 As described, a process is possible where partial evaporation over a length of more than 25 cm is achieved through a high velocity in the microchannel of >10 cm/s. The coolant channel is oriented 50% horizontally and orthogonally to the reaction coordinate. Maintaining the highest possible coolant temperature, close to the boiling point, is also possible using reactors according to existing patents. WO 2017/013003 This is beneficial from an energy perspective as well as for reasons of isothermity in the reactor, because the supply channel of the parallelized evaporation structures also lies perpendicular to the reaction coordinate.

The parallelization of reactors, including microstructured reactors, is well-documented in the literature for constructing plants with higher production capacities. Parallelization with regard to the distribution of the reaction stream is used, for example, in... US6149882 , WO 97/32208 , DE 198 09 477 , WO 99/41005 , DE 198 06 848 , WO 00/51720 and DE 601 08 482 T2 described. In US9822049 Furthermore, a common closed-loop coolant system is described, utilizing the phase transition of the coolant for cooling. Crucially, this document states that heat removal from all reactors occurs in a common steam drum, while pressure control takes place downstream of each reactor in the two-phase coolant, allowing for precise adjustment of the reaction progress in each reactor.

• 1) Werden Katalysatoren unterschiedlichen Alters, im Extremfall also frischer hochaktiver Katalysator und Katalysator, welcher sich bereits für mehrere Jahre im Reaktor befindet und bereits desaktiviert hat, verwendet, werden in den jeweiligen Teilströmen des Kühlmittels stark unterschiedliche Drücke benötigt. So werden im Beispiel der Fischer-Tropsch Synthese 15 bar und 30 bar benötigt, was einer Siedetemperatur von 198°C bzw. 234°C entspricht. Erfolgt die Wärmeauskopplung nach der Zusammenlegung der Teilströme (zum Beispiel wie in US9822049 ) so orientiert sich die maximal zur Verfügung stehende Kühlmitteltemperatur für Rekuperation mit eintretendem Kühlmittel in die Reaktoren an dem niedrigsten Druck in den jeweiligen Teilströmen. Auch kommt es zu einer Abkühlung des Zweiphasengemischs nach der Druckeinstellung bei den Teilströmen, die auf höherem Druck arbeiten. Somit muss die Anhebung der Kühlmitteltemperatur auf Siedetemperatur nach der/den Pumpe/n vor dem Eintritt in die Reaktoren von einer anderen Energiequelle gespeist werden, was den Prozess weniger wirtschaftlich macht.
• 2) Die Druckregelung eines Zweiphasengemischs ist mit regulären Regelventilen ohne Druckpulsationen nahezu unmöglich, insofern ist die in US9822049 beschriebene Kombination nicht vorteilhaft.
• 3) Wird die Wärmeauskopplung aus einem zweiphasigen Kühlmittel vorgenommen, so erhöht sich der Flächenbedarf in dem betreffenden Wärmetauscher aufgrund des größeren Gesamtvolumenstroms und je nach Temperatur des zweiten Fluids zur Wärmeauskopplung kann es zur Unterkühlung des bereits flüssigen Anteils des Kühlmittels kommen. Ist der Flüssigkeitsanteil im Kühlmittel nach Überströmen der Reaktoren hoch, so besteht hier ein erhöhter Bedarf an Temperaturerhöhung des rückgekühlten und flüssigen Kühlmittels vor Wiedereintritt in die Reaktoren.

Key challenges in the parallelization of reactors that have not been satisfactorily addressed by current technology include the following:

• 1) If catalysts of different ages are used, in the extreme case a fresh, highly active catalyst and a catalyst that has been in the reactor for several years and has already deactivated, significantly different pressures are required in the respective coolant streams. For example, in the Fischer-Tropsch synthesis, 15 bar and 30 bar are required, corresponding to boiling points of 198°C and 234°C, respectively. If heat extraction takes place after the merging of the streams (for example, as in US9822049 The maximum available coolant temperature for recuperation, as coolant enters the reactors, is determined by the lowest pressure in the respective partial flows. Furthermore, the two-phase mixture cools down after pressure adjustment in the partial flows operating at higher pressure. Therefore, raising the coolant temperature to boiling point after the pump(s) and before it enters the reactors must be powered by another energy source, making the process less economical.
• 2) Pressure regulation of a two-phase mixture is virtually impossible with regular control valves without pressure pulsations; therefore, the in US9822049 The described combination is not advantageous.
• 3) If heat extraction is performed from a two-phase coolant, the surface area required in the relevant heat exchanger increases due to the larger overall volume flow rate. Depending on the temperature of the second fluid used for heat extraction, the already liquid portion of the coolant may become subcooled. If the liquid fraction in the coolant is high after passing through the reactors, there is an increased need to raise the temperature of the recooled, liquid coolant before it re-enters the reactors.

There are currently no solutions that can satisfactorily address these challenges.

Therefore, based on the known state of the art, there is still a considerable need to improve the current state of the art, especially with regard to the three specifically mentioned challenges.

Task:

The object of the present invention was therefore to overcome the disadvantages of the prior art described above and to provide devices and methods which no longer exhibit these problems, or at least only to a significantly lesser extent.

In particular, more efficient methods and equipment should be made available.

Further tasks arise for the expert when considering the requirements and from the following description.

Solution:

These and other problems that arise for the person skilled in the art from the present description are solved by the items described in the independent claims.

Preferred and particularly advantageous embodiments are described in the dependent claims and the following description.

Detailed description of the invention:

Within the scope of the present invention, all quantity specifications, unless otherwise stated, are to be understood as weight specifications.

Within the scope of the present invention, the term "ambient temperature" means a temperature of 20°C. Unless otherwise specified, temperature readings are in degrees Celsius (°C).

Unless otherwise stated, the reactions or process steps listed are carried out at ambient pressure (=normal pressure/atmospheric pressure), i.e. at 1013 mbar.

Unless otherwise stated, pressure specifications within the scope of the present invention mean absolute pressure specifications, i.e., x bar (i.e., without a subscript) means x bar absolute (bar _a ) and not x bar gauge.

• - umfassend mindestens einen Mikroreaktor auf Basis von mindestens zwei übereinandergeschichteten Reaktoruntereinheiten,
• - wobei jede Reaktoruntereinheit mindestens eine, oder genau eine, Reaktionslage und mindestens eine, oder genau eine, Kühllage umfasst, und
• - wobei jede Reaktoruntereinheit mit eigener Kühlmitteleinleitung und eigener Kühlmittelausleitung versehen ist,

bei dem
jeder Reaktoruntereinheit als eigene Komponenten
ein erster Wärmetauscher,
eine erste Phasentrennvorrichtung zur Aufteilung des Kühlmittelstroms,
eine erste Regelvorrichtung zur Druckregelung auf den gewünschten Siededruck für die Kühlwasserzufuhr, und
eine zweite Regelvorrichtung zur Regelung des Flüssigkeitsniveaus in der ersten Phasentrennvorrichtung,
zugeordnet sind, wobei

• - der Kühlmittelausleitung der jeweiligen Reaktoruntereinheit jeweils ein erster (nur für diese Reaktoruntereinheit zuständigen) Wärmetauscher zur Rekuperation von in dem ausgeleiteten Kühlmittelstrom enthaltener Wärme (insbesondere bevorzugt gegen die Kühlwasserzufuhr zum Reaktor) nachgeschaltet ist;
• - dem ersten Wärmetauscher nachgeschaltet eine erste Phasentrennvorrichtung zur Aufteilung des Kühlmittelstroms in
  • - einen Gasphasenstrom (Dampfphasenstrom) und
  • - einen Flüssigphasenstrom,
  wobei in der aus der jeweiligen ersten Phasentrennvorrichtung herausgeführten Leitung für den Gasphasenstrom eine erste Regelvorrichtung, insbesondere Druckregelvorrichtung, zur Druckregelung auf den gewünschten Siededruck (Siededruck entspricht Reaktionstemperatur gemäß T-p-Diagramm) für die jeweilige Kühlwasserzufuhr sowie in der aus der jeweiligen ersten Phasentrennvorrichtung herausgeführten Leitung für dem Flüssigphasenstrom jeweils eine zweite Regelvorrichtung zur Regelung des Niveaus in der ersten Phasentrennvorrichtung angeordnet ist;
• - die aus den ersten Phasentrennvorrichtungen stammenden Leitungen für die Gasphasenströme stromabwärts der ersten Regelvorrichtung in eine Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Gasphasenströme führen, aus der dann ein zusammengeführter Gasphasenstrom abgeleitet wird;
• - stromabwärts der Vorrichtung zur Zusammenführung der Gasphasenströme ein zweiter Wärmetauscher angeordnet ist, der konfiguriert ist, aus dem zusammengeführten Gasphasenstrom abgeleitete Wärme für andere Gewerke auszukoppeln;
• - sich stromabwärts der zweiten Regelvorrichtung zur Regelung des Niveaus in der ersten Phasentrennvorrichtung angeordnet eine Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Flüssigphasenströme befindet, aus der dann ein zusammengeführter Flüssigphasenstrom abgeleitet wird;
• - stromabwärts des zweiten Wärmetauschers und der Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Flüssigphasenströme eine Vorrichtung zur Zusammenführung der beiden (aus den jeweiligen Gasphasenströmen und den jeweiligen Flüssigphasenströmen resultierenden, und jetzt jeweils flüssigen) Gas- und Flüssigphasenströmen und Vereinigung zu einem zusammengeführten Kühlmittelstrom angeordnet ist;
• - sich stromabwärts der Vorrichtung zur Zusammenführung angeordnet eine Rückführvorrichtung, bevorzugt eine Pumpe, konfiguriert, den zusammengeführten Kühlmittelstrom als einen Rücklauf-Kühlmittelstrom zurückzuführen;
• - stromabwärts der Rückführvorrichtung eine Vorrichtung zur Aufteilung des Rücklauf-Kühlmittelstroms in der Anzahl der Reaktoruntereinheiten entsprechende Kühlmittel-Teilströme befindet, und
• - dann die Kühlmittel-Teilströme via den jeweils ersten Wärmetauscher, wobei das Kühlmittel im jeweils ersten Wärmetauscher auf (die gewünschte) Vorlauftemperatur, bevorzugt nahe am Siedepunkt, besonders bevorzugt 1 bis 20°C, insbesondere bevorzugt 1 bis 8°C, unter dem Siedepunkt des Kühlmittels, aufgeheizt wird, in die Kühlmitteleinleitung der jeweiligen Reaktoruntereinheit geführt wird.

The present invention relates, in a first essential subject matter, to a device for carrying out exothermic reactions,

• - comprising at least one microreactor based on at least two stacked reactor subunits,
• - wherein each reactor subunit comprises at least one, or exactly one, reaction layer and at least one, or exactly one, cooling layer, and
• - wherein each reactor subunit is equipped with its own coolant inlet and coolant outlet,

in which
each reactor subunit as its own components
a first heat exchanger,
a first phase separation device for splitting the coolant flow,
a first control device for pressure regulation to the desired boiling pressure for the cooling water supply, and
a second control device for regulating the liquid level in the first phase separation device,
are assigned, whereby

• - a first heat exchanger (responsible only for this reactor subunit) is connected downstream of the coolant discharge of the respective reactor subunit for the recovery of heat contained in the discharged coolant flow (especially preferably against the cooling water supply to the reactor);
• - downstream of the first heat exchanger, a first phase separation device is used to divide the coolant flow into
  • - a gas phase stream (vapor phase stream) and
  • - a liquid phase stream,
  wherein a first control device, in particular a pressure control device, for pressure control to the desired boiling pressure (boiling pressure corresponds to reaction temperature according to Tp diagram) for the respective cooling water supply is arranged in the line for the gas phase flow leading out of the respective first phase separation device, and a second control device for controlling the level in the first phase separation device is arranged in the line for the liquid phase flow leading out of the respective first phase separation device;
• - the lines for the gas phase flows originating from the first phase separation devices lead downstream of the first control device into a device for combining the gas phase flows corresponding to the number of reactor subunits, from from which a combined gas phase stream is then derived;
• - a second heat exchanger is arranged downstream of the device for combining the gas phase streams, which is configured to extract heat derived from the combined gas phase stream for other trades;
• - a device for combining the liquid phase streams corresponding to the number of reactor subunits is arranged downstream of the second control device for controlling the level in the first phase separation device, from which a combined liquid phase stream is then derived;
• - downstream of the second heat exchanger and the device for combining the liquid phase streams corresponding to the number of reactor subunits, a device for combining the two (resulting from the respective gas phase streams and the respective liquid phase streams, and now each liquid) gas and liquid phase streams and combining them into a combined coolant stream is arranged;
• - arranged downstream of the merging device, a return device, preferably a pump, is configured to return the merged coolant flow as a return coolant flow;
• - downstream of the recirculation device, there is a device for dividing the return coolant flow into coolant subflows corresponding to the number of reactor subunits, and
• - then the coolant partial flows via the respective first heat exchanger, wherein the coolant in the respective first heat exchanger is heated to (the desired) supply temperature, preferably close to the boiling point, particularly preferably 1 to 20°C, particularly preferably 1 to 8°C, below the boiling point of the coolant, and is led into the coolant inlet of the respective reactor subunit.

It should be noted that the gas phase stream may be partially or completely condensed after passing through the second heat exchanger. For the sake of simplicity, however, it will continue to be referred to as a gas phase stream (until it merges with the liquid phase stream from the first phase separation device); firstly, because it may still be (partially) gaseous after the second heat exchanger if heat extraction is low, and secondly, to distinguish it from the liquid phase stream. If necessary, further condensation can take place downstream, as described below.

In preferred embodiments of the invention, the pressure control for the reactor is achieved on the gas phase stream, while the liquid fraction is continuously discharged according to the level in the vessel. The gas phase stream is then completely condensed in the subsequent second heat exchanger. In this embodiment, a pressurized buffer vessel can be arranged upstream of the return pump, from which the return pump draws its gas.

In further preferred embodiments, gas ( _N₂ or other inert gas) can be added to or removed from the pressurized buffer tank. This is because the fill level in the pressurized buffer tank changes when evaporation begins in the reactor and controls the overall pressure level in the circuit. Since the device of the present invention represents a closed circuit, a pressure increase can occur if steam suddenly forms from a liquid-filled system; this can be countered by adding or removing gas, so that this addition or removal of gas, via gas inlets and outlets configured for this purpose in these embodiments, is provided as a control step or control device.

The pressure in the reactor is ultimately influenced by all components; according to the invention, the control is preferably not achieved by means of the feedback device (i.e., in particular not by speed control of a pump as a feedback device).

In preferred embodiments of the present invention, a third heat exchanger for pre-cooling the combined coolant flow against a heat-receiving substance (i.e., coolant, preferably water, air or similar, in particular water), in particular with simple mass flow control, is arranged between the merging device and the return device as a further component in the course of the combined coolant flow.

In preferred embodiments of the present invention, a second phase separation device is arranged upstream of the recirculation device, which is preferably configured to recool the combined coolant flow by controlling the amount of coolant supplied to the maximum inlet temperature specified by the downstream recirculation device.

At this point in the circuit, the coolant is therefore completely liquid, meaning the gas phase(s) are/are completely condensed. If the coolant is already completely condensed, i.e., completely liquid, before this point, the third heat exchanger, the second phase separation device, or the (pressurized) buffer tank may be unnecessary.

According to the invention, the third heat exchanger is used particularly when there is a risk that the coolant is still too hot, that a vapor phase is formed due to its expansion, or that cavitation is likely due to the suction effect of the downstream return device (pump). In further embodiments of the present invention, the third heat exchanger can be switched on and off in a controlled manner.

In preferred embodiments of the present invention, the device comprises, between the device for dividing the return coolant flow into the number of reactor subunits corresponding to the number of coolant partial flows and the respective first heat exchanger, a third control device assigned to the respective reactor subunit, which is configured to direct the coolant partial flows via a respective bypass line, bypassing the first heat exchanger, directly into the coolant inlet, in the event that the temperature of the coolant flow is too close to the boiling temperature of the coolant.

This device component or step serves to prevent excessively hot coolant from entering the respective reactor subunit, because the already hot coolant would be heated even further by the first heat exchanger, so that (there is a risk that) it would already be present as a two-phase mass flow under boiling conditions; this would drastically reduce the cooling efficiency.

In preferred embodiments of the present invention, the second heat exchanger is configured to transfer a portion of the heat contained in the gas phase stream via indirect contact to a heat-receiving substance (i.e., a coolant), preferably water, in particular steam, for the operation of a reverse water-gas shift reaction.

In preferred embodiments of the present invention, the device is configured to use the heat extracted via the second heat exchanger for other purposes, such as steam generation, in particular for the generation of accompanying water for a rWGS, or for desorption of _CO2 from a direct air capture plant or other uses, such as general heat applications.

In some preferred embodiments of the present invention, a further control device is located between the coolant return device and the device for dividing the return coolant flow into coolant partial flows corresponding to the number of reactor subunits. This control device sets a pressure that then enables division into the individual coolant partial flows if the pressure of the return coolant flow is insufficient or too high.

In preferred embodiments of the present invention, the device does not include any electrical heating devices that are active during continuous operation or operation.

One advantage of the device or method according to the invention is that no electric heating devices are required during continuous operation (running, normal, or controlled operation). However, in some variants, it may be preferable to implement electric heating devices to bring the circuit to the "starting temperature" (i.e., the coolant to preferably 1 to 20°C, particularly preferably 1 to 8°C below boiling point) during commissioning or starting. According to the invention, no electric heating devices are required during continuous operation (running, normal, or controlled operation). It is also possible, accordingly, not to implement any electric heating devices at all and to bring the circuit to temperature during commissioning or starting using other methods known in the art (for example, utilizing heat from other processes or solar thermal energy), or, for example, to install electric heating devices only temporarily and then remove them.

In some embodiments of the present invention, it is possible to combine gas phase streams (vapor phase stream) and liquid phase streams originating from several respective reactor subunits before the second heat exchanger or before the merging device, and then to return the combined coolant as a whole and only divide it back into partial streams before introducing it into the respective reactor subunits.

In some embodiments of the present invention, at least one flow indicator/flow control device and/or at least one pressure indicator/pressure control device may be arranged upstream of the third control device in the direction of flow.

The present invention is based on the fact that the reactor subunits can operate at different pressures in the boiling water circuit. (Depending on the specific conditions in each reactor subunit, for example, catalyst activity). For this reason, the recuperation of coolant from the feed line to the pressure control point after the reactor is also carried out separately for each reactor subunit. Heat extraction for external use is performed simply, i.e., with combined coolant flows comprising coolant from several, preferably all, reactor subunits, as is the recirculation device (pump) for the (combined) coolant.

• - mindestens einen Mikroreaktor auf Basis von mindestens zwei übereinandergeschichteten Reaktoruntereinheiten umfasst,
• - wobei jede Reaktoruntereinheit mindestens eine Reaktionslage und mindestens eine Kühllage umfasst, und
• - wobei jede Reaktoruntereinheit mit eigener Kühlmitteleinleitung und eigener Kühlmittelausleitung versehen ist,

und wobei
jeder Reaktoruntereinheit als eigene Komponenten
ein erster Wärmetauscher,
eine erste Phasentrennvorrichtung zur Aufteilung des Kühlmittelstroms,
eine erste Regelvorrichtung zur Druckregelung auf den gewünschten Siededruck für die Kühlwasserzufuhr, und
eine zweite Regelvorrichtung zur Regelung des Flüssigkeitsniveaus in der ersten Phasentrennvorrichtung,
zugeordnet sind und
das Verfahren die Schritte i) bis vi) umfasst,
wobei

• i) der aus der Kühlmittelausleitung der jeweiligen Reaktoruntereinheit ausgeleitete Kühlmittelstrom in einem ersten (d.h. nur für diese zuständigen) Wärmetauscher einer Rekuperation von enthaltener Wärme (gegen die Kühlwasserzufuhr zum Reaktor unterworfen wird;
• ii) anschließend in einer jeweiligen ersten Phasentrennvorrichtung der jeweilige Kühlmittelstrom in
  • - einen Gasphasenstrom (Dampfphasenstrom) und
  • - Flüssigphasenstrom
  aufgeteilt wird, wobei jeder der beiden aus der jeweiligen ersten Phasentrennvorrichtung herausgeführten Teilströme einer individuellen Druckregelung unterworfen wird;
• iii) die aus der ersten Phasentrennvorrichtung stammenden Gasphasenströme stromabwärts ihrer Druckregelung über eine Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Gasphasenströme zu einem zusammengeführten Gasphasenstrom zusammengeführt werden;
• iv) stromabwärts davon aus dem zusammengeführten Gasphasenstrom über einen zweiten Wärmetauscher aus dem Gasphasenstrom Wärme abgeleitet und für andere Gewerke ausgekoppelt wird;
• v) die aus der ersten Phasentrennvorrichtung stammenden Flüssigphasenströme stromabwärts ihrer Druckregelung über eine Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Flüssigphasenströme zu einem zusammengeführten Flüssigphasenstrom zusammengeführt werden;
• vi) stromabwärts des zweiten Wärmetauschers und der Vorrichtung zur Zusammenführung der der Anzahl der Reaktoruntereinheiten entsprechenden Flüssigphasenströme Gasphasenströme und Flüssigphasenströme zusammengeführt und zu einem Kühlmittelstrom vereinigt werden;
• viii) der zusammengeführte Kühlmittelstrom danach mittels einer Rückführvorrichtung, bevorzugt einer Pumpe, als Rücklauf-Kühlmittelstrom zurückgeführt wird;
• ix) der Rücklauf-Kühlmittelstrom über eine Vorrichtung zur Aufteilung des Rücklauf-Kühlmittelstroms in der Anzahl der Reaktoruntereinheiten entsprechende Kühlmittel-Teilströme aufgeteilt wird;
• x) dann die der Anzahl der Reaktoruntereinheiten entsprechenden Kühlmittel-Teilströme via den jeweils ersten Wärmetauscher auf (die gewünschte) Vorlauftemperatur, bevorzugt nahe am Siedepunkt, besonders bevorzugt 1 bis 20°C, insbesondere bevorzugt 1 bis 8°C, unter dem Siedepunkt des Kühlmittels, aufgeheizt werden, und in die Kühlmitteleinleitung der jeweiligen Reaktoruntereinheit zurückgeführt werden.

The present invention relates in a second essential subject matter to a method for boiling water cooling in devices for carrying out exothermic reactions, in particular the devices according to the invention,
wherein the device

• - comprises at least one microreactor based on at least two stacked reactor subunits,
• - wherein each reactor subunit comprises at least one reaction layer and at least one cooling layer, and
• - wherein each reactor subunit is equipped with its own coolant inlet and coolant outlet,

and whereby
each reactor subunit as its own components
a first heat exchanger,
a first phase separation device for splitting the coolant flow,
a first control device for pressure regulation to the desired boiling pressure for the cooling water supply, and
a second control device for regulating the liquid level in the first phase separation device,
are assigned and
the procedure comprises steps i) to vi)
where

• i) the coolant flow discharged from the coolant outlet of the respective reactor subunit is subjected to a first (i.e., only responsible for this) heat exchanger for the recuperation of contained heat (against the cooling water supply to the reactor;
• ii) subsequently in a respective first phase separation device the respective coolant flow into
  • - a gas phase stream (vapor phase stream) and
  • - Liquid phase current
  is divided, with each of the two partial flows leading out of the respective first phase separation device being subjected to individual pressure control;
• iii) the gas phase streams originating from the first phase separation device are combined downstream of its pressure control via a device for combining the gas phase streams corresponding to the number of reactor subunits into a combined gas phase stream;
• iv) downstream of this, heat is extracted from the combined gas phase stream via a second heat exchanger and extracted for other trades;
• v) the liquid phase streams originating from the first phase separation device are combined downstream of its pressure control via a device for combining the liquid phase streams corresponding to the number of reactor subunits into a combined liquid phase stream;
• vi) downstream of the second heat exchanger and the device for combining the liquid phase flows corresponding to the number of reactor subunits, the gas phase flows and liquid phase flows are combined and merged into a coolant flow;
• viii) the combined coolant flow is then returned as a return coolant flow by means of a return device, preferably a pump;
• ix) the return coolant flow is divided into coolant subflows corresponding to the number of reactor subunits via a device for dividing the return coolant flow;
• x) then the coolant partial flows corresponding to the number of reactor subunits are heated via the respective first heat exchanger to (the desired) supply temperature, preferably close to the boiling point, particularly preferably 1 to 20°C, particularly preferably 1 to 8°C, below the boiling point of the coolant, and returned to the coolant inlet of the respective reactor subunit.

• vii) ein Vorkühlen des zusammengeführten Kühlmittelstroms in einem dritten Wärmetauscher gegen ein zweites Kühlmittel (Wasser, Luft o.ä.), insbesondere mit einfacher Massestromregelung.

In preferred embodiments of the present invention, the step between steps vi) and viii) is performed

• vii) pre-cooling of the combined coolant flow in a third heat exchanger against a second coolant (water, air or similar), especially with simple mass flow control.

In preferred embodiments of the present invention, the second heat exchanger transfers a portion of the heat contained in the gas phase stream via indirect contact to a coolant, preferably water, in particular steam, for the operation of a reverse water-gas shift reaction.

In preferred embodiments of the present invention, the heat extracted via the second heat exchanger is used for other applications such as steam generation, in particular for the generation of accompanying water for a rWGS, or for desorption of _CO2 from a direct air capture plant or other uses, such as general heat applications.

• - dem direkt aus der ersten Phasentrennungsvorrichtung stammendem Flüssigkeitsphasenstrom,
• - stromabwärts des zweiten Wärmetauschers der aus dem zweiten Wärmetauscher kommenden Kühlmittelstrom (ganz oder teilweise kondensierter Gasphasenstrom), oder
• - in der Vorrichtung zur Zusammenführung der Gas- und Flüssigphasenstrom, zugegeben werden kann.

In preferred embodiments of the present invention, in which the steam coming from the first phase separation devices is used as process steam for other trades (i.e., extracted/drained from the system), the difference in the amount of cooling liquid can be replaced by fresh water, which

• - the liquid phase stream originating directly from the first phase separation device,
• - downstream of the second heat exchanger, the coolant flow coming from the second heat exchanger (fully or partially condensed gas phase flow), or
• - can be added to the device for combining the gas and liquid phase streams.

In preferred embodiments of the devices or method according to the invention, cooling in the microreactors takes place in cross-current or counter-current flow, particularly preferably in counter-current flow.

Last but not least, the present invention relates to the use of the device according to the invention for Fischer-Tropsch reactions or methanol synthesis.

• 1) Die Rekuperation zur Vorwärmung erfolgt bei der vorliegenden Erfindung direkt nach Durchströmen des Kühlmittels in jedem Reaktorteilstrang, also nach jedem Einzel-Reaktor. Damit ist gewährleistet, dass die eintretende Kühlmitteltemperatur nahe an den Siedepunkt vorgewärmt wird. Auf diese Art entfallen im Regelbetrieb bzw. unter stationären Bedingungen elektrische Vorheizer. Es kann eine zwischen 1°C bis 5°C niedrigere Temperatur als die Siedetemperatur in jedem Teilstrom gewährleistet werden. Durch die Teilstromregelung vor dem rekuperativen Wärmetaucher im Zulauf der jeweiligen Reaktoruntereinheit ist dieser Bereich noch erweiterbar auf bevorzugt bis zu 8°C unter Siedetemperatur. Da jeder Reaktor einen Druckverlust für das Kühlmittel von maximal 0.5 bar bis 1 bar aufweist und die Siedetemperatur dabei etwa 2°C fällt, wird darüber hinaus sichergestellt, dass die Siedetemperatur in der Vorheizung nicht überschritten wird.
• 2) Nach jeder Rekuperation erfolgt eine Gas-Flüssigtrennung des Kühlmittels, wobei eine Levelregelung eine pulsationsfreie Druckeinstellung über den Gasphasenteilstrang erzielt wird. Die ausgetragene Flüssigkeit aus der ersten Phasentrenneinheit kann schließlich trotz Bildung eines Zweiphasengemischs bei Entspannung auf den niedrigsten Druck im vereinten Kühlmittelkreislauf mit dem kondensierten Anteil des Kühlmittels, oder bei Nutzung des Dampfes als Prozessdampf für andere Gewerke durch Frischwasser ersetzt, gemischt und wieder zu den Reaktoren zurückgepumpt werden. Um dampfförmige Anteile im Vorlauf der Pumpe zu vermeiden, wird der gemischte Strom zusätzlich durch Mengenregelung mit Kühlmittel gezielt auf die von der Pumpe vorgegebene maximale Eintrittstemperatur rückgekühlt werden (d.h. unterhalb die Temperatur, bei der keine Kavitätsprobleme auftreten bzw. welche die verbauten Komponenten aushalten). Aus dem in der Phasentrennung abgezogenen Dampf können etwa mindestens 70%, meist sogar über 80% der in der Gesamtheit der Reaktoren freigesetzten Wärmeleistung an andere Gewerke abgegeben werden.

The problems described above, in particular the three specifically listed challenges, are solved by the devices and methods (guidelines) according to the invention, especially as follows:

• 1) In the present invention, recuperation for preheating takes place directly after the coolant flows through each reactor sub-stream, i.e., after each individual reactor. This ensures that the incoming coolant temperature is preheated close to the boiling point. In this way, electric preheaters are unnecessary during normal operation or under steady-state conditions. A temperature between 1°C and 5°C lower than the boiling point can be guaranteed in each sub-stream. By controlling the sub-stream upstream of the recuperative heat exchanger in the inlet of the respective reactor sub-unit, this range can be extended, preferably to up to 8°C below the boiling point. Since each reactor has a pressure drop for the coolant of a maximum of 0.5 bar to 1 bar, and the boiling point drops by approximately 2°C in this process, it is also ensured that the boiling point is not exceeded during preheating.
• 2) After each recuperation cycle, the coolant undergoes gas-liquid separation, with level control ensuring a pulsation-free pressure setting across the gas phase section. Despite the formation of a two-phase mixture, the liquid discharged from the first phase separation unit can be mixed with the condensed portion of the coolant upon expansion to the lowest pressure in the combined coolant circuit. Alternatively, if the steam is used as process steam for other applications, it can be replaced with fresh water, mixed, and pumped back to the reactors. To prevent vaporous components in the pump's feed line, the mixed stream is additionally cooled with coolant to the maximum inlet temperature specified by the pump (i.e., below the temperature at which no cavity problems occur or which the installed components can withstand) by means of flow control. At least 70%, and usually over 80%, of the total heat output released by the reactors can be transferred to other applications from the steam extracted during phase separation.

• - individuelle Rekuperation in der Kühlmittelteilstrom jeder Reaktoruntereinheit;
• - Druckregelung in jedem Kühlmittelteilstrom nach Gas-Flüssigtrennung in jedem Kühlmittelteilstrom;
• - Auskopplung der im Trockendampf enthaltenen Reaktionswärme für andere Gewerke in einem gemeinsamen Wärmtauscher;
• - optional Vorkühlung der gemeinsam rückgeführten flüssigen Phase des Kühlmittels vor der Pumpe mit einfacher Massenstromregelung eines zweiten Kühlmittels.

The present invention differs from the prior art in particular by a combination of the following features, which is not known from the prior art:

• - individual recovery in the coolant partial flow of each reactor sub-unit;
• - Pressure regulation in each coolant partial stream after gas-liquid separation in each coolant partial stream;
• - Extraction of the reaction heat contained in the dry steam for use by other trades in a common heat exchanger;
• - optional pre-cooling of the jointly recirculated liquid phase of the coolant before the Pump with simple mass flow control of a second coolant.

With the devices and methods according to the invention, it is therefore possible to work considerably more efficiently compared to the prior art.

• - Maximierung der Vorlauftemperatur des Kühlmittels (nahe am Siedepunkt) in jedem Teilstrom ohne Gefahr der Überschreitung des Siedepunkts und ohne Zusatzenergie (nur mit Hilfe der Reaktorabwärme) durch individuelle Rekuperation in jedem Kühlmittelteilstrom;
• - pulsationsfreie Druckregelung in jedem Teilstrom durch Gas-Flüssigtrennung vor Druckregelung;
• - maximale Nutzung der Reaktionswärme durch Wärmeübertragung aus einem gemeinsamen Wärmetauscher für die Dampfphase;
• - gezielte Vorkühlung der gemeinsam rückgeführten flüssigen Phase vor der Pumpe.

The devices and methods according to the invention offer several significant advantages over the prior art, some, but not all, of which are the following:

• - Maximizing the coolant supply temperature (close to the boiling point) in each partial stream without risk of exceeding the boiling point and without additional energy (only using reactor waste heat) through individual recuperation in each coolant partial stream;
• - Pulsation-free pressure control in each partial flow through gas-liquid separation prior to pressure control;
• - Maximum utilization of the heat of reaction through heat transfer from a common heat exchanger for the vapor phase;
• - targeted pre-cooling of the jointly recirculated liquid phase before the pump.

The person skilled in the art can, within the scope of their general expertise, determine the exact design of the described devices, insofar as these are not explicitly described in this description, such as size, wall thicknesses, materials, etc., according to the reaction conditions intended for a specific reaction.

Insofar as parts or the entire device are described as "consisting of" in the description of the devices according to the invention, this is to be understood as referring to the aforementioned essential components. This does not exclude obvious or inherent parts such as pipes, valves, screws, housings, measuring devices, storage containers for reactants/products, etc.

Unless explicitly described otherwise, the individual parts of the devices are interconnected in a manner customary and known in the field.

The various embodiments of the present invention, e.g. - but not exclusively - those of the various dependent claims, can be combined with each other in any way, provided that such combinations do not contradict each other.

It should be noted here that all described parts and functions are claimed as essential to the invention, both individually and in any combination, especially the details shown in the drawing. Modifications to this are familiar to those skilled in the art.

Furthermore, it is noted that the broadest possible scope of protection is sought. Therefore, the disclosure contained in the claims can also be specified by features that are described by further features (even if these further features are not necessarily included). It is explicitly pointed out that parentheses and the term "in particular" are intended to emphasize the optionality of features in the respective context (which does not imply that a feature is to be considered mandatory in the corresponding context without such indication).

Examples:

The invention will now be further explained with reference to the following non-limiting examples. In the experiments, several reactors according to the invention were arranged one above the other to form a multiple reactor arrangement according to the invention.

Example:

A reactor with two reactor subunits was operated with recirculated cooling water. The first reactor subunit was already significantly deactivated due to its operating hours and sulfur contamination of the feed gas. The second reactor subunit was freshly filled with catalyst and had only been operated for a few hours. Due to the deactivation of the first reactor subunit, it was operated at 215°C. The pressure at its first pressure regulator in the gas outlet from its first phase separation unit was 18.2 bar _g , and the CO conversion was 58%. The second reactor subunit was operated at 202°C, with a pressure of 14.1 bar g at its first pressure regulator in the gas outlet from its first phase separation unit. The CO conversion in the second reactor subunit was 71%. Through complete heat recovery at the first heat exchangers, the reactor inlet temperature of the recirculated coolant could be set to 210°C (for the first reactor subunit) and 197°C (for the second reactor subunit), respectively. 340 kg/h of water was fed into the first and second reactor subunits. The energy recovered through condensation of the generated steam The water generated in the first phase was used entirely in a second, shared heat exchanger for steam generation for an RWGS process at 9 bar _g . The condensed water mass flow, combined with liquid water from the first phase separation devices, was cooled to 133°C in a third heat exchanger using 25°C cooling water and then pumped back to a pressure of 20 bar _g . The cooling water heated up to 43°C in the process.

Character description:

The present invention is explained in more detail below with reference to the drawing. The drawing is not to be interpreted as limiting and is not to scale. The drawing is schematic and does not include all features found in conventional devices, but is reduced to those essential for the present invention and its understanding; for example, screws, connections, etc., are not shown or not shown in detail. The drawing represents a preferred embodiment, but not all possible embodiments or modifications according to the invention are illustrated in this drawing. The same reference numerals in the figure, the description, and the claims denote identical features.

1 The present invention is illustrated in a highly schematic manner. The figure above shows a reactor Rx with a certain number of reactor subunits (each consisting of a cooling layer and a reaction layer), represented by the variable "x". For the sake of simplicity, in the following, designations relating to the corresponding reactor subunit x will not always refer to it as such, but will simply indicate the corresponding device part with an "x"added; for example, W-1-x for the heat exchanger associated with the xth reactor subunit.

A feed gas stream F, comprising reaction gas, is fed into this reactor, and a product gas stream P exits the reactor after the reaction gas has been converted. These conversions include, for example, well-known exothermic reactions, i.e., reactions that require cooling of the reaction layers (or where cooling is at least advantageous).

A heated coolant stream K1a-x is discharged from the reactor. This coolant stream K1a-x is subjected to heat transfer (recuperation) via a first heat exchanger W-1-x against the coolant partial stream Kx (as described below), which is returned (thereby heating the coolant partial stream Kx), and then introduced into the respective first phase separation device B-1-x.

In this first phase separation device B-1-x, the still relatively hot coolant is split into a gas phase stream (vapor phase) K2a-x and a liquid phase stream K2b-x.

In the line for the gas phase flow K2a-x leading out of the respective first phase separation device B-1-x, there is a first control device D-R1-x. This device regulates the pressure to the desired boiling pressure for the respective cooling water supply K1e-x (see also the description above).

The gas phase streams K2a-x originating from the first phase separation devices B-1-x are guided downstream of the first control device D-R1-x into a device VZ-G for combining the gas phase streams K2a-x into a single gas phase stream. Only this combined gas phase stream K2a is then derived from this device VZ-G.

Downstream of the device for combining the gas phase streams VZ-G, a second heat exchanger W-2 is arranged, configured to extract heat from the combined gas phase stream K2a and extract it for other applications. This is illustrated in the figure as follows: a stream of a heat-receiving substance WE-E (this substance is not referred to here as a coolant for clarity; it is usually water) enters the heat exchanger W-2 and receives heat from the combined gas phase stream K2a; the now heated heat-receiving substance WE-A then exits the heat exchanger W-2, and the heat content can be used for other purposes, for example, to operate a reverse water-gas shift reaction or for extraction for other applications. For the sake of simplicity, the combined gas phase stream K2a exiting the heat exchanger is referred to here as a gap phase stream, although it is usually at least partially condensed. This is readily understandable to a person skilled in the art and therefore does not require a detailed description. In each line leading out of the first phase isolating device B-1-x for the liquid phase current K2b-x, there is a second control device D-R2-x. This device regulates the (liquid) level in the first phase isolating device B-1-x.

Downstream of the second control device D-R2-x for controlling the level in the first phase separation device B-1-x is a device VZ-F for combining the number of reactors subunits corresponding liquid phase streams K2b-x are located, from which a combined liquid phase stream K2b is then derived.

Furthermore, downstream of the second heat exchanger W-2 and the device VZ-F for combining the liquid phase flows K2b-x, a device VZ-T for combining the two gas and liquid phase flows K2a, K2b and combining them into a combined coolant flow K3 is arranged.

The combined coolant flow K3 can then, optionally but as shown in the figure, be directed via a third heat exchanger W-3 to pre-cool the combined coolant flow K3 against another heat-receiving substance.

As with the second heat exchanger shown above, the figure illustrates that a stream of heat-receiving substance WE-E (this substance is not referred to as coolant here for better distinction; it is usually water) enters the heat exchanger W-3 and receives heat from the combined coolant stream K3; subsequently, the now heated heat-receiving substance WE-A exits the heat exchanger W-3, and the heat content can be used for other purposes.

Downstream of the merging device VZ-T or the heat exchanger W-3, if present, a second phase separation device or (pressurized) buffer tank B-2 can be arranged, through which the combined coolant flow K3 can be further treated, if necessary; in particular to avoid vaporous components in the supply line to the downstream recirculation device (pump) P-1. In this buffer tank B-2, the mixed flow can additionally be cooled down to the maximum inlet temperature specified by the downstream recirculation device (pump) P-1 by means of controlled coolant flow (i.e., below the temperature at which no cavity problems occur or which the installed components can withstand).

Downstream of the merging device VZ-T or the optional heat exchanger W-3, or the second phase separation device B-2, if present, a recirculation device P-1 is arranged which is configured to return the merged coolant flow K3 as a return coolant flow KR to the reactor.

The return coolant flow KR coming from the recirculation device P-1 is then directed to a device VA for dividing the return coolant flow KR into coolant partial flows Kx corresponding to the number of reactor subunits.

From this point onwards, the devices are again divided into reactor subunits.

The coolant partial flows Kx generated in the device VA for splitting the return coolant flow KR are then fed via the first heat exchanger W-1-x into the coolant inlet K1e-x of the respective reactor subunit. For this purpose, the coolant is heated to supply temperature in the first heat exchanger W-1-x.

Furthermore, optionally, and as shown in the figure, a third control device BP-R-x (for controlling the bypass flow at W-1-x) assigned to each reactor subunit R-x can be provided between the device VA for splitting the return coolant flow KR and the respective first heat exchanger W-1-x. If this is present, it is preferably configured to direct the coolant partial flows Kx via a respective bypass line BP-x, bypassing the respective first heat exchanger W-1-x, directly into the respective coolant inlet K1e-x, in the event that the temperature of the coolant flow KR is too close to the boiling point of the coolant.

It should be clarified that the dashed line illustrates which respective assemblies/devices are present multiple times, i.e., in a number corresponding to the number of reactor subunits used. (In variants of the present invention, it is also possible to use a microreactor with a certain number of reactor subunits, of which only a portion is used (for example, for capacity reasons) – in this case, the number of other devices to be used results from the number of reactor subunits actually used, not from the maximum number of usable reactor subunits.) Devices not enclosed by the dashed line are used only once within the scope of the present invention. (In variants of the present invention, one, several, or all of these devices may also be implemented multiple times; for example, to double the capacity – however, the actual number of devices not enclosed by the dashed line does not depend on the number of reactor subunits used.) This corresponds to the hybrid status (switching from multiple assignment to general assignment or vice versa) of the device for combining gas phase streams. The dashed line passes through VZ-G and the device for combining liquid phase flows VZ-F, as well as the device for dividing the return coolant flow KR into coolant partial flows Kx, to illustrate this hybrid status. Although not shown in the drawing, it should be noted that in some embodiments of the present invention, at least one flow indicator/flow control device and at least one pressure indicator/pressure control device may be arranged upstream of the third control device BP-Rx.

Reference symbol list:

WE-A

escaping heat-receiving substance

WE-E

incoming heat-receiving material

F

Feed (reaction gas)

P

Product (reaction gas)

H-1-x

(Optional) electric heating device assigned to the xth reactor sub-unit

W-1-x

first heat exchanger assigned to the xth reactor subunit

W-2

second heat exchanger

W-3

third heat exchanger

K1e-x

Coolant inlet/coolant flow leading to the xth reactor subunit

K1a-x

Coolant flow discharged from the xth reactor subunit (from the reactor subunit)

K2a-x

Gas phase flow (vapor phase flow) assigned to the xth reactor subunit

K2a

Gas phase flow (vapor phase flow) (combined from x gas phase flows (vapor phase flows))

K2b-x

liquid phase stream assigned to the xth reactor subunit

K2b

Liquid phase stream (combined from x liquid phase streams)

K3

Combined coolant flow

KR

return coolant flow

VZ-G

Device for combining x gas phase streams

VZ-F

Device for combining x liquid phase streams

VZ-T

Device for combining gas phase and liquid phase streams

D-R1-x

first control device assigned to the xth reactor subunit (for pressure control to the desired boiling pressure)

D-R2-x

second control device (for level control) assigned to the xth reactor subunit

BP-R-x

third control device assigned to the xth reactor subunit for controlling the bypass current at W-1-x

P-1

Return device

B-1-x

first phase separation device assigned to the xth reactor subunit

B-2

(Optional) second phase separation device or (pressurized) buffer tank

R-x

xth reactor subunit

BP-x

bypass line assigned to the xth reactor subunit

VA

Device for dividing the return coolant flow (KR) into x coolant partial flows (Kx),

x

sequential number of the respective reactor subunit used

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 2013/0165536 A1 [0004]
• WO 2017/013003 [0004]
• US 6149882 [0005]
• WO 97/32208 [0005]
• DE 198 09 477 [0005]
• WO 99/41005 [0005]
• DE 198 06 848 [0005]
• WO 00/51720 [0005]
• DE 601 08 482 T2 [0005]
• US 9822049 [0005, 0006]

Claims (11)

Device for carrying out exothermic reactions, comprising at least one microreactor based on at least two stacked reactor subunits (Rx), wherein each reactor subunit (Rx) comprises at least one reaction layer and at least one cooling layer, and wherein each reactor subunit (Rx) is provided with its own coolant inlet (K1e-x) and its own coolant outlet (K1a-x), characterized in that each reactor subunit is assigned as separate components a first heat exchanger (W-1-x), a first phase separation device (B-1-x) for splitting the coolant flow (K1a-x), a first control device (D-R1-x) for pressure control to the desired boiling pressure for the cooling water supply (K1e-x), and a second control device (D-R2-x) for controlling the liquid level in the first phase separation device (B-1-x), wherein the coolant outlet of the respective reactor subunit is each provided with a first heat exchanger (W-1-x) for recuperating heat from the discharged coolant. a first phase separation device (B-1-x) is connected downstream of the coolant flow (K1a-x) containing heat; - a first phase separation device (B-1-x) is connected downstream of the heat exchanger (W-1-x) for dividing the coolant flow (K1a-x) into - a gas phase flow (vapor phase flow) (K2a-x) and - a liquid phase flow (K2b-x), wherein a first control device (D-R1-x) for pressure control to the desired boiling pressure for the respective cooling water supply (K1e-x) is arranged in the line for the gas phase flow (K2a-x) leading out of the respective first phase separation device (B-1-x), and a second control device (D-R2-x) for controlling the level in the first phase separation device (B-1-x) is arranged in the respective line for the liquid phase flow (K2b-x) leading out of the respective first phase separation device (B-1-x); - the lines for the gas phase streams (K2a-x) originating from the first phase separation devices (B-1-x) lead downstream of the first control device (D-R1-x) into a device (VZ-G) for combining the gas phase streams (K2a-x) corresponding to the number of reactor subunits, from which a combined gas phase stream (K2a) is then derived; - downstream of the device for combining the gas phase streams (VZ-G) a second heat exchanger (W-2) is arranged, which is configured to extract heat from the combined gas phase stream (K2a) and to supply it to other systems; - downstream of the second control device (D-R2-x) for controlling the level in the first phase separation device (B-1-x), a device (VZ-F) for combining the liquid phase streams (K2b-x) corresponding to the number of reactor subunits is located, from which a combined liquid phase stream (K2b) is then derived; - downstream of the second heat exchanger (W-2) and the device (VZ-F) for combining the liquid phase streams (K2b-x) corresponding to the number of reactor subunits, a device (VZ-T) for combining the two gas and liquid phase streams (K2a, K2b) and combining them into a combined coolant stream (K3) is located; - downstream of the device for combining (VZ-T), a recirculation device (P-1) is located, configured to return the combined coolant stream (K3) as a return coolant stream (KR); - downstream of the recirculation device (P-1) there is a device (VA) for dividing the return coolant flow (KR) into coolant partial flows (Kx) corresponding to the number of reactor subunits; and - then the coolant partial flows (Kx) are fed via the first heat exchanger (W-1-x) in each case, where the coolant is heated to supply temperature in the first heat exchanger (W-1-x) in each case, into the coolant inlet (K1e-x) of the respective reactor subunit; where x is the consecutive number of the respective reactor subunit (Rx) used. Device according to Claim 1 , characterized in that, as a further component, a third heat exchanger (W-3) is arranged in the course of the combined coolant flow (K3) for pre-cooling the combined coolant flow (K3) against a second coolant between the device for combining (VZ-T) and the return device (P-1). Device according to Claim 1 or 2 , characterized in that between the device (VA) for dividing the return coolant flow (KR) into coolant partial flows (Kx) corresponding to the number of reactor subunits and the respective first heat exchanger (W-1-x) a third control device (BP-Rx) assigned to the respective reactor subunit (Rx) is provided, which is configured to direct the coolant partial flows (Kx) via a respective bypass line (BP-x) bypassing the respective first heat exchanger (W-1-x) directly into the respective coolant inlet (K1e-x) in the event that the temperature of the coolant flow (KR) is too close to the boiling temperature of the coolant. device according to one of the Claims 1 until 3 , characterized in that the second heat exchanger (W-2) is configured to transfer a portion of the heat contained in the gas phase stream (K2a-x) via indirect contact to a heat-receiving substance for the operation of a reverse water-gas shift reaction. device according to one of the Claims 1 until 4 , in particular Claim 1 , characterized in that it is configured to use the heat extracted via the second heat exchanger (W-2) for other trades to generate steam. device according to one of the Claims 1 until 5 , in particular Claim 1 , characterized in that a second phase separation device (B-2) is arranged upstream of the recirculation device (P-1), which is preferably configured to recool the combined coolant flow (K3) by controlling the amount of coolant supplied to the maximum inlet temperature specified by the downstream recirculation device (P-1). device according to one of the Claims 1 until 6 , in particular Claim 1 , characterized in that at least one flow indicator/flow control device and/or at least one pressure indicator/pressure control device is arranged in the direction of flow upstream of the third control device (BP-Rx). A method for boiling water cooling in devices for carrying out exothermic reactions, wherein the device comprises at least one microreactor based on at least two stacked reactor subunits (rx), wherein each reactor subunit (Rx) comprises a reaction layer and a cooling layer, and wherein each reactor subunit (Rx) is provided with its own coolant inlet (K1e-x) and its own coolant outlet (K1a-x), characterized in that each reactor subunit is assigned as separate components a first heat exchanger (W-1-x), a first phase separation device (B-1-x) for splitting the coolant flow, a first control device (D-R1-x) for pressure control to the desired boiling pressure for the cooling water supply (K1e-x), and a second control device (D-R2-x) for controlling the liquid level in the first phase separation device (B-1-x), and the method comprises steps i) to vi), wherein i) is the coolant flow discharged from the coolant outlet of the respective reactor subunit. (K1a-x) is subjected to heat recovery in a first heat exchanger (W-1-x); ii) the respective coolant stream is then split in a respective first phase separation device (B-1-x) into a gas phase stream (vapor phase stream) (K2a-x) and a liquid phase stream (K2b-x), with each of the two partial streams (K2a-x) and (K2b-x) exiting the respective first phase separation device (B-1-x) being subjected to individual pressure control; iii) the gas phase streams (K2a-x) originating from the first phase separation device (B-1-x) are combined downstream of their pressure control via a device (VZ-G) for combining the gas phase streams corresponding to the number of reactor subunits into a combined gas phase stream (K2a); iv) downstream of this, heat is extracted from the combined gas phase stream (K2a) via a second heat exchanger (W-2) and extracted for other applications; v) the liquid phase streams (K2b-x) originating from the first phase separation device (B-1-x) are combined downstream of their pressure control via a device (VZ-F) for combining the x liquid phase streams into a combined liquid phase stream (K2b); vi) downstream of the second heat exchanger (W-2) and the device (VZ-F) for combining the liquid phase streams (K2b-x) corresponding to the number of reactor subunits, the gas and liquid phase streams (K2a, K2b) are combined and merged into a coolant stream (K3); viii) the combined coolant stream (K3) is then returned as a return coolant stream (KR) by means of a recirculation device; ix) the return coolant flow (KR) is divided via a device (VA) for dividing the return coolant flow (KR) into coolant partial flows (Kx) corresponding to the number of reactor subunits; x) then the coolant partial flows (Kx) corresponding to the number of reactor subunits are heated to supply temperature via the respective first heat exchanger (W-1-x) and returned to the coolant inlet (K1e-x) of the respective reactor subunit (Rx), where x is the consecutive number of the respective reactor subunit used. Procedure according to Claim 8 , characterized in that, as step vii) pre-cooling of the combined cooling agent telstroms (K3) in a third heat exchanger (W-3) against a second coolant between steps vi) and viii). Procedure according to Claim 8 or 9 , characterized in that the second heat exchanger (W-2) transfers a portion of the heat contained in the gas phase stream (K2a) via indirect contact to a further coolant for the operation of a reverse water-gas shift reaction. Use of the device according to one of the Claims 1 until 7 for Fischer-Tropsch reactions or methanol synthesis.