Cooled reactor for performing exothermic equilibrium reactions

Abstract

The invention relates to a reactor for carrying out an exothermic equilibrium reaction, in particular methanol synthesis and / or ammonia synthesis, by means of a heterogeneously catalyzed reaction of the corresponding reactant gases, which reactor makes it possible to overcome the establishment of the reaction equilibrium in the reactor. For this purpose, according to the invention, the coolant temperature along the longitudinal coordinates of the reactor is influenced and thus optimized by means of the supercooling of the coolant.

Description

Technical Field

[0001] The invention relates to a reactor for carrying out an exothermic equilibrium reaction in which a gaseous input mixture is reacted at least partly over a solid catalyst to provide a product mixture. Example applications include methanol synthesis by reaction of a synthesis gas comprising hydrogen and carbon oxides, and ammonia synthesis by reaction of an input gas comprising hydrogen and nitrogen, in each case as a heterogeneously catalyzed reaction over a solid catalyst. Background Art

[0002] Reactors for carrying out exothermic equilibrium reactions have long been known to those skilled in the art. Reactions of this type of particular industrial importance are, for example, the synthesis of methanol by heterogeneous catalytic reaction of synthesis gas, i.e. a mixture of hydrogen and carbon oxides. Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, electronic distribution 1998, chapter "Methanol", subchapter 5.2 "Synthesis", describes various basic processes for producing methanol by catalytic conversion of synthesis gas containing hydrogen and carbon oxides, in which such reactors are used.

[0003] Another exothermic equilibrium reaction of particular industrial importance is the ammonia synthesis, which is explained in detail in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, electronic distribution 1998, chapter "Ammonia", subchapter 4 "Production".

[0004] For example, a modern two-stage process for producing methanol is disclosed in European patent specification EP 0 790 226 B1. Methanol is produced in a circulation process, wherein a mixture of fresh synthesis gas and partially reacted synthesis gas is first supplied to a water-cooled reactor and then to an air-cooled reactor, in each reactor the synthesis gas is converted into methanol over a copper-based catalyst. The methanol produced in this process is separated from the synthesis gas to be recycled, which is then passed through the air-cooled reactor as a coolant in a countercurrent manner and preheated to a temperature of 220° C. to 280° C. before being introduced into the first synthesis reactor. A portion of the synthesis gas to be recycled is removed from the process as a purge stream to prevent inert components from accumulating in the synthesis loop. This measure is also taught in German laid-open specification DE 2934332 A1 and European patent application EP 1016643 A1.

[0005] In the case of methanol synthesis and also ammonia synthesis, unconverted methane from the synthesis gas production is considered to be an inert component, since this compound does not undergo further conversion under the conditions of methanol or ammonia synthesis. The same applies to argon which enters the synthesis gas production via the feed stream.

[0006] Water-cooled reactor stages typically achieve the main conversion of the syngas (CO, CO2, H2) and remove the largest part of the heat of reaction, while gas-cooled stages still convert a significant portion of the syngas under milder conditions.

[0007] Water-cooled reactors (WCR) are typically shell-and-tube reactors including corresponding tube end plates, wherein catalyst is filled into the tubes and cooled by boiling water / steam generation on the shell side (internal space) around the tubes. In gas-cooled reactors (GCR), cooling is achieved with input gas, which is heated on the way to the first reaction stage (WCR) through the tube, while catalyst is filled around the tubes, and the reaction occurs on the shell side of the GCR. In terms of their nominal width, the reaction stages are connected to large or very large pipelines; depending on the equipment capacity, a tube diameter of up to 1m is possible. This is primarily due to a large amount of gas, which is recycled to the second stage (recycled gas) and mixed with fresh gas, i.e., fresh synthesis gas from gas production. After preheating in the GCR, the resulting gas mixture of recycled gas and fresh gas is supplied to the first reaction stage (WCR). The amount of recycled gas is typically significantly greater than the amount of fresh gas and depends on the conversion achieved in the reactor section. The recycle ratio RR of the amount of recycle gas (R) to the amount of fresh gas (F) (RR=R / F) frequently exceeds 2 and in many cases even exceeds 3.5. The lower the conversion of the synthesis gas per pass through the reactor section, the higher the recycle ratio RR is required to achieve a sufficient yield.

[0008] This results in a corresponding increase in the amount of circulating gas, thereby increasing the space velocity of the reactor and requiring a larger nominal pipe width for the connecting pipes, and also results in an increased demand for compression energy (higher flow rate and pressure drop).

[0009] Current ammonia synthesis processes are described, for example, in patent publication WO 2002 / 038499 A1. In the case of synthesis gas for ammonia synthesis, in contrast to synthesis gas for methanol synthesis, it is important to completely eliminate the proportion of carbon oxides, so that hydrogen enters the ammonia synthesis as the only remaining synthesis gas component. This is achieved first by converting the carbon monoxide present in the synthesis gas (CO conversion), subsequently removing carbon dioxide by a sorption process, and finally by freezing the gas fraction.

[0010] A disadvantage of the above-mentioned synthesis reactions is that, as exothermic equilibrium reactions, they are limited by the reaction equilibrium. It is therefore desirable to specify reactors and methods for their operation that can overcome these limitations. Summary of the invention

[0011] Accordingly, the object of the present invention is to specify a reactor and a method for its operation which do not have the described disadvantages of the reactors known from the prior art and which, in particular, provide a high conversion of the target product of the exothermic equilibrium reaction in a single pass of the reactor and offer the opportunity to influence and thus optimize the reaction conditions along the longitudinal coordinate of the reactor, for example in the case of methanol synthesis which leads to a reduction of the recycle ratio to smaller values, as is known when using reactors familiar from the prior art.

[0012] This object is achieved in a first aspect by a reactor having the features of claim 1 and in another aspect by a method having the features of claim 8. Further embodiments according to further aspects of the invention are evident from the dependent claims of the corresponding categories.

[0013] A fluid connection between two zones of a reactor according to the invention is understood to mean any type of connection which makes it possible that a fluid, for example an input gas stream or a synthesis gas product stream, can flow from one of the two zones to the other, disregarding any intervening zones or components.

[0014] Devices for introduction, discharge, etc. are to be understood as meaning all devices, device components, assemblies and components which allow a particular fluid to leave the spatial region under consideration (e.g. a container). This refers in particular to pipes, pumps, compressors, other conveying devices and corresponding openings in the container wall.

[0015] Catalytic activity, in particular in relation to the different catalytic activities when comparing two different catalysts, is understood to mean the degree of conversion achieved per unit length of catalyst bed from reactants to products. The activity is influenced by the chemical composition, doping, poisoning, available surface area, etc. of the catalyst material, but also by the geometry of the catalyst particles and the structural parameters of the catalyst bed (e.g. its porosity or packing density). Due to the exothermic nature of the reaction under consideration, a high catalytic activity is associated with a high heat release per unit length of the catalyst bed.

[0016] In the context of this specification, tubular reactor is understood to mean a reaction device including a tube or multiple tubes with a generally circular cross section, the tube is filled with a filler of one or more catalysts, wherein one or more tubes are generally made of a metal material. Reactant stream enters the tubular reactor at one of the open tube ends, flows through the tubular reactor continuously, and is therefore converted into a product stream, which is continuously discharged at the opposite end of the open tube. The axial backmixing of the material stream flowing through the tubular reactor occurs only to a very small extent (if any). Therefore, exothermic reaction can cause the release of a more or less obvious maximum value (so-called hot spot) of the axial temperature curve according to the heat of reaction. In the context of this specification, reaction temperature range is understood to mean the temperature range covered by the temperature curve.

[0017] A plate reactor is understood to mean a reaction device in which a catalyst filling / catalyst bed of solid particulate catalyst is arranged between two generally parallel plates. The sides of this arrangement which are not used for the introduction of reactants / discharge of reaction products are usually sealed at their edges, for example by fluid-tight contact with the inner wall of the reactor housing or by suitable welding.

[0018] Plate reactor is also understood to mean a reaction device in which the catalyst bed is not arranged between two flat plates but between two pillow plates. In the context of the present invention, the pillow plate is composed of two metal sheets, which are joined at the edge, preferably welded, and are distributed on its surface with a plurality of other joints, preferably welding points, which also join the two plates to each other. Such plates can be produced in an automated manner by a robot or machine, and are therefore very economical and efficient. After welding, the metal sheet is expanded by hydraulic forming (usually injecting fluid under high pressure), so that a pillow-shaped channel is formed between the metal sheets, and a heating or cooling fluid can pass through the channel. Therefore, these heat transfer spaces make it possible to supply heat energy to certain areas of the reactor and remove heat energy from certain areas of the reactor by the passage of a heating or cooling fluid.

[0019] When pillow plates are used, the reaction zone can be configured so that in the reactor, two pillow plates are initially arranged substantially parallel. In the context of the present invention, substantially parallel is understood to mean that the alignment of the pillow plates relative to each other deviates from parallel by at most + / -20°, preferably at most + / -10°, particularly preferably at most + / -5°, very particularly preferably at most + / -2°. Subsequently, the free space between the pillow plates can be filled with a filling of catalyst in the form of solids, particles, microparticles or pellets, wherein the lateral terminations of the resulting catalyst bed are formed by meshes, grids, perforated plates, grids, fillings of inert material and / or the inner walls of the reactor.

[0020] It is particularly preferred that at least one, preferably two or more, further pillow plates spaced apart from one another are adjacent parallel to the arrangement, thus forming together a plate pack, and that the cavities between the pillow plates are filled with a catalyst filling. This makes it possible to achieve a compact sandwich-like structure in the reaction zone with an intensive cooling device extending over the length of the reaction zone. The individual catalyst fillings are supplied in parallel with the reaction gas mixture. Depending on the cavity filled with the catalyst, the plate pack can be aligned parallel or perpendicular to the longitudinal axis of the reactor.

[0021] The distance between the pillow plates can be selected according to the heat release of the reaction to be carried out: for strongly exothermic reactions, the distance is made smaller than for weaker exothermic reactions. A smaller plate distance is preferred in the first reaction zone because the maximum conversion is achieved here and the maximum heat removal must be achieved here. In the case of methanol synthesis, the pillow plate distance in the first reaction zone is preferably 20 to 45 mm. This distance refers to the distance from center line to center line, that is, the net distance between the plates is correspondingly smaller depending on the thickness of the pillow plates and the expansion of the cavity. In addition, the distance is adapted to the size of the catalyst particles to ensure optimal heat removal and good bulk material behavior when filling and emptying the catalyst without bridging. In the second and subsequent reaction zones, the distance is usually made larger.

[0022] An advantage of plate reactors compared to tubular reactors is that generally a larger cooling area per unit volume of catalyst is available.

[0023] In this specification, a longitudinal axis is understood to mean the axis of the device or apparatus corresponding to its direction of greatest extension. In the context of this specification, an arrangement of a device or apparatus with its longitudinal axis parallel to the vertical as defined by gravity is understood to mean an upright arrangement.

[0024] The coolant used in the cooling of the reactor according to the invention is preferably a medium close to its boiling point and therefore easily evaporates under the reaction pressure in the reaction temperature range. This ensures good heat removal from the catalyst bed due to good heat transfer on the evaporation medium side during the exothermic reaction and allows accurate temperature control via pressure. In order to establish different temperature conditions in different stages, the pressure on the cooling medium side in the inner space is controlled. As the normal working time of the catalyst increases, the conditions can be adjusted by correspondingly adjusting the pressure in the inner space, thereby affecting the reaction temperature, so as to, for example, maintain a correspondingly high conversion rate.

[0025] Taking into account the desired reaction conditions, methanol synthesis can use water or steam as a heat transfer medium, for example. However, when using water, achieving the desired temperature range requires establishing a relatively large pressure difference to cover a wide temperature range (e.g. 250°C: about 40 bar, 264°C: about 50 bar). In contrast, the use of evaporative heat transfer oil (e.g. Dowtherm A) in the loop for steam generation makes it possible to operate within a very narrow pressure range while still covering a large temperature range (e.g.: 255°C: 0.97 bar, 305°C: 2.60 bar, corresponding to a temperature range of 50°C at a pressure difference of only 1.6 bar). This makes it possible to use a simple heat transfer oil steam drum at the corresponding equipment level (about 20 to 25m), and the feed height of the shortest line can be used alone to establish a separate pressure and temperature range.

[0026] In the context of the present description, the coolant cooling device must meet the requirement of being able to establish, together with the pressure control device, a defined coolant temperature (subcooling) below the boiling point of the coolant at the pressure in the interior space. The interior space is understood to mean the free space between the outer wall of the at least one tubular reactor or the outer wall of the at least one plate reactor and the inner wall of the housing through which the coolant can pass.

[0027] Conditions of the exothermic equilibrium reaction in general and methanol synthesis conditions / ammonia synthesis conditions in particular are to be understood as meaning process conditions known per se to the person skilled in the art, in particular temperature, pressure and residence time, as described, for example, above and discussed in detail in the relevant literature, and under which at least a partial, but preferably industrially relevant, conversion of the reactants of the corresponding process into products takes place. The same applies to the selection of suitable catalysts and their suitable operating conditions, since in the context of the present invention both of the processes described are operated under heterogeneous catalysis, in which corresponding reactors for the methanol synthesis and reactors for the ammonia synthesis are known per se to the person skilled in the art and are described, for example, in the literature mentioned at the outset.

[0028] The invention is based on the discovery that optimal temperature management, in particular in the axial direction of the reactor, makes it possible to significantly improve the productivity / space-time yield along the reaction path. By using the cooling concept according to the invention, the temperature profile along the reaction path is significantly improved, so that significantly higher single-pass conversions are achieved. The reactor cooling according to the invention can be used for catalyst-filled tubular reactors and catalyst-filled plate reactors.

[0029] When using the reactor according to the invention, the formation of by-products during the methanol synthesis is also reduced compared to the prior art.

[0030] Improved temperature profiles in the reactor can also be achieved in principle using catalyst layer management. This would include using less active catalysts in the regions where the highest conversion (heat release rate) and therefore the highest temperature are expected, and using more active catalysts in regions where lower conversion is expected. However, such catalyst layer management is relatively inflexible, since different catalyst layers must be selected and defined based on specific catalyst activities and corresponding gas compositions. However, as a result of the continuous deactivation of the catalyst, the catalyst activity changes during the normal operating time of the synthesis plant.

[0031] The layer management of the reaction bed and the associated cooling must be matched to one another. During normal catalyst operating time and associated catalyst deactivation, conditions change and it is desirable to adjust the reaction temperature and the accompanying cooling / cooling temperature in order to at least partially compensate for the deactivation and ensure high conversion and low by-product formation. Reactors known in the prior art allow cooling only for the entire reactor; however, usually not all catalyst layers experience the same degree of deactivation during operating time. Therefore, establishing specific reaction conditions is always a compromise.

[0032] The process according to the invention allows the reaction conditions to be adjusted individually according to the catalyst activity, the gas composition in each stage and the potential presence of two or more different catalyst layers (layer management) and also along the longitudinal axis of the catalytic fixed bed reactor during normal working hours. This achieves high conversion rates and low by-product formation over the entire reactor.

[0033] Optimized temperature management also reduces the maximum temperatures (and temperature peaks, so-called hot spots) in the catalyst bed. In addition to removing by-products, such as water in methanol synthesis, from the reaction system, this also has a positive effect on the uptime of the catalyst. It is known that high temperatures in the catalyst bed lead to faster deactivation of the catalyst.

[0034] One aspect of the present invention is to use a reactor arrangement with an evaporative cooling medium, such as water or heat transfer oil, on the cooling side of the reactor. This makes it possible to ensure very good heat transfer on the cooling side in the zone where the cooling medium is partially evaporated. In the case of an upright arrangement of the reactor, evaporation preferably occurs in the upper part of the reactor, where the conversion rate on the reaction side is the highest, and corresponding cooling is necessary and useful. The cooling medium is therefore introduced into the lower region of the cooling side of the reactor in liquid and supercooled form, while the reaction gas enters the reaction side from above. In principle, the cooling medium flows countercurrently with the reaction gas on the cooling side (inner space).

[0035] In one example, the cooling medium is recirculated by natural circulation, i.e., by density differences due to evaporation and / or temperature differences along the cooling circuit, but forced circulation can also be achieved by using a pump in the cooling circuit that pumps subcooled liquid from a steam drum serving as a cooling medium reservoir to the cooling side of the reactor.

[0036] In order to optimize the reactor performance, the cooling medium provided from the reservoir in a saturated state is supercooled before entering the cooling side of the reactor. The reduced cooling temperature leads to a reduction in the reaction temperature on the process side of the reactor, which is advantageous in terms of the thermodynamic balance of the exothermic reaction and ultimately improves the conversion rate. Lower temperatures are also advantageous in other aspects (e.g., reducing by-product formation, extending catalyst service life).

[0037] The reactor used may be any relevant reaction apparatus in which a countercurrent flow of cooling medium and reaction gas can be achieved. Examples include tubular reactors, shell and tube reactors and plate reactors.

[0038] Subcooling of the cooling medium can be achieved using various heat exchanger types. If natural circulation is used, low pressure drop on the cooling medium side is critical. In order to achieve an appropriate recirculation rate of the cooling medium, in one example, the liquid delivery height from the cooling reservoir can be configured taking into account the total pressure drop in the cooling circuit.

[0039] One option for achieving the desired subcooling could be an air cooler installed in the downcomer between the coolant reservoir and the reactor cooling side inlet.The cross-sectional area of ​​the heat exchanger for the coolant side is configured such that a low pressure drop is achieved.

[0040] In order to adjust the temperature of the cooling medium when entering the cooling side of the reactor, a bypass around the heat exchanger for supercooling can be used to reduce the flow through the heat exchanger, thereby producing reduced supercooling. In the bypass in an example, a control valve is installed to control the desired flow through the bypass / through the heat exchanger. If necessary, another valve can be optionally installed downstream of the heat exchanger to throttle the flow through the heat exchanger to a minimum value. This will make it possible to bypass the heat exchanger completely. In an example, the control valve is controlled by a temperature controller, which controls the temperature of the cooling medium before entering the cooling side of the reactor. In another example, the measured temperature of the reactor product gas on the process side at the reactor outlet can be used to control the bypass valve on the above-mentioned temperature controller for cooling directly or indirectly via cascade.

[0041] When using air coolers, the cooling can also be controlled via conventional control devices (eg speed controllers, fan blade adjusters, shutters). However, the bypass solution will be applicable to all types of heat exchangers.

[0042] In order to improve the heat integration, according to one example, it is useful to use a heat exchanger cooled with the cooling medium discharged from the reactor instead of an air cooler. This preheats the cooling medium while, on the hot side of the heat exchanger, the cooling medium of the reactor cooling circuit is cooled. Preheating makes it possible to recover more heat from the system and increase the steam production in the steam drum.

[0043] Such heat exchangers can be, for example, double-tube heat exchangers, multi-tube heat exchangers, plate heat exchangers or other types of heat exchangers. In any case, it is preferred to use a countercurrent system between the hot side and the cold side to achieve optimal control and efficiency. In addition, the design of the heat exchanger must ensure a low pressure drop on the hot side connected to the coolant loop of the reactor system. In one example, the heat exchanger is integrated into the pipeline between the coolant reservoir (steam drum) and the reactor cooling side inlet. In the case of an upright arrangement, the flow of the hot side flows downward from the upper end of the heat exchanger, and the preheating of the cooling medium on the cold side preferably flows upward from the lower inlet. In addition, in one example, the design of the heat exchanger makes each side of the heat exchanger use only one channel, and avoids multiple channels to ensure good controllability of the heat transfer power.

[0044] The invention proposes a reactor for carrying out exothermic equilibrium reactions, in particular for methanol synthesis and / or ammonia synthesis by heterogeneous catalytic reaction of synthesis gas, which makes it possible to influence and thus optimize the reaction conditions along the longitudinal coordinate of the reactor, for example in the case of methanol synthesis, which leads to a reduction of the recycle ratio to smaller values, as is known when using reactors familiar from the prior art. As a result, the corresponding recycle pipes, loop compressors, etc. can be made smaller or, in some cases, can even be completely omitted. This reduces the corresponding capital costs.

[0045] Optimizing the reaction temperature profile along the longitudinal axis of the reactor further reduces the formation of undesirable by-products, thus providing a purer target product and reducing purification efforts.

[0046] Other specific embodiments of the present invention

[0047] In a second aspect of the present invention, the reactor according to the present invention is characterized in that the first cooling section of at least one tubular reactor or plate reactor includes the last section of the catalyst filling in the flow direction of the input mixed flow and the product mixed flow. The first cooling section of the reactor coincides with the last section of the catalyst filling. Since the coolant introduced into the inner space of this section has been supercooled relative to its boiling point using a coolant cooling device, the coolant exists in liquid form, thereby allowing a cooling temperature below the boiling point to be established. The resulting temperature reduction in the catalyst bed makes it possible to move the reaction equilibrium in this part of the catalyst bed in the direction of the reaction product. Even in the case where the reaction equilibrium has been established previously (i.e., in the first part of the catalyst bed), this also allows the additional formation of reaction products.

[0048] In a third aspect of the invention, the reactor according to the invention is characterized in that the last section of the catalyst filling accounts for 0% to 30% of the total length of the catalyst filling, preferably 0% to 40% of the total length of the catalyst filling, and most preferably 0% to 50% of the total length of the catalyst filling. Studies have shown that the first cooling section of the reactor is dimensioned accordingly so that particularly favorable product yields can be achieved. In contrast, if the first cooling section of the reactor is still made larger, the second cooling section of the reactor may become too small, with the result that the reactant conversion / product yield achieved here is too small and too few reaction products are produced in equilibrium over the entire reactor.

[0049] In a fourth aspect of the invention, the reactor according to the invention is characterized in that the coolant cooling device is adjustable so that the temperature of the coolant flow before entering the inner space is at least 3° C., preferably at least 10° C., most preferably at least 20° C. below the boiling temperature of the coolant at the coolant pressure. Studies have shown that a corresponding selection of the subcooling temperature in the first cooling section of the reactor makes it possible to achieve particularly advantageous product yields.

[0050] In a fifth aspect of the invention, the reactor according to the invention is characterized in that the reactor comprises a plurality of tubular reactors or plate reactors filled with a catalyst filling, which are arranged in parallel in a shell relative to their longitudinal axes. An increase in the number of reactor tubes in the cooling shell leads to an increase in the product yield.

[0051] In a sixth aspect of the invention, the reactor according to the invention is characterized in that the reactor is arranged upright relative to its longitudinal axis, so that the reactant inlet and the coolant outlet are located at the upper end of the reactor, and the product outlet and the coolant inlet are located at the lower end of the reactor. This is particularly advantageous because it has the result that the second cooling section is arranged at the top of the reactor. Since the coolant boils in this second cooling section of the reactor and is discharged from the inner space as a vapor or as a two-phase flow, the delivery of the coolant can be achieved at least in part by natural circulation, with the result that the corresponding delivery device, such as a coolant pump, can be made smaller or completely omitted.

[0052] A seventh aspect of the invention relates to the use of a reactor according to any of the above aspects for performing methanol synthesis and / or for ammonia synthesis.

[0053] In a ninth aspect of the invention, the process according to the invention is characterized in that the first cooling section of at least one tubular reactor or plate reactor comprises the last section of the catalyst filling in the flow direction of the input mixed stream and the product mixed stream. The advantages associated with this embodiment of the process correspond to those explained for the reactor according to the invention in conjunction with the second aspect of the invention.

[0054] In a tenth aspect of the invention, the process according to the invention is characterized in that the last section of the catalyst packing accounts for 0% to 30% of the total length of the catalyst packing, preferably 0% to 40% of the total length of the catalyst packing, most preferably 0% to 50% of the total length of the catalyst packing. The advantages associated with this embodiment of the process correspond to those explained for the reactor according to the invention in conjunction with the third aspect of the invention.

[0055] In an eleventh aspect of the invention, the method according to the invention is characterized in that the coolant cooling device is adjustable so that the temperature of the coolant flow before entering the inner space is at least 3° C., preferably at least 10° C., most preferably at least 20° C. below the boiling temperature of the coolant at the coolant pressure. The advantages associated with this embodiment of the method correspond to those explained for the reactor according to the invention in conjunction with the fourth aspect of the invention.

[0056] In a twelfth aspect of the invention, the method according to the invention is characterized in that the reactor comprises a plurality of tubular reactors or plate reactors filled with a catalyst filling, which are arranged in parallel in a housing with respect to their longitudinal axes. The advantages associated with this embodiment of the method correspond to those explained for the reactor according to the invention in conjunction with the fifth aspect of the invention.

[0057] In a thirteenth aspect of the invention, the method according to the invention is characterized in that the reactor is arranged upright relative to its longitudinal axis, so that the reactant inlet and the coolant outlet are located at the upper end of the reactor, and the product outlet and the coolant inlet are located at the lower end of the reactor. The advantages associated with this embodiment of the method correspond to those explained for the reactor according to the invention in conjunction with the sixth aspect of the invention.

[0058] In a fourteenth aspect of the present invention, the method according to the present invention is characterized in that steps (2) to (5) are configured as follows:

[0059] (2) providing a gaseous input mixed stream containing hydrogen and carbon oxides as reactant components;

[0060] (3) introducing a gaseous input mixture stream into at least one tubular reactor or plate reactor via a reactant inlet;

[0061] (4) at least partially reacting a gaseous input mixed stream under methanol synthesis conditions to provide a fluid product mixed stream comprising methanol as a product component and unconverted reactant components;

[0062] (5) Discharging a fluid product mixture stream from at least one tubular reactor or plate reactor via a product outlet.

[0063] This provides an advantageous method for methanol synthesis using the reactor according to the invention.

[0064] In a fifteenth aspect of the present invention, the method according to the present invention is characterized in that steps (2) to (5) are configured as follows:

[0065] (2) providing a gaseous input mixed stream containing hydrogen and nitrogen as reactant components;

[0066] (3) introducing a gaseous input mixture stream into at least one tubular reactor or plate reactor via a reactant inlet;

[0067] (4) at least partially reacting a gaseous input mixed stream under ammonia synthesis conditions to provide a gaseous product mixed stream comprising ammonia as a product component and unconverted reactant components;

[0068] (5) Discharging a gaseous product mixture stream from at least one tubular reactor or plate reactor via a product outlet.

[0069] This provides an advantageous method for carrying out ammonia synthesis with the reactor according to the invention.

[0070] Worked and Numerical Examples

[0071] Developments, advantages and possible applications of the invention are also apparent from the following description of working and numerical examples and drawings. All features described and / or depicted form the invention by themselves or in any combination, regardless of how they are combined in the claims or dependent references therein.

[0072] In the figure:

[0073] Figure 1 is a schematic diagram of an apparatus / process comprising a reactor according to the present invention;

[0074] Figure 2 is an axial temperature profile in a reactor according to a first embodiment of the present invention;

[0075] Figure 3 is an axial temperature profile in a reactor according to a second embodiment of the present invention;

[0076] Figure 4 is an axial temperature curve in a reactor according to the third embodiment of the present invention.

[0077] Hereinafter, "not shown" will be understood to mean that the element in the figure in question is not illustrated, but is still present according to the description.

[0078] Figure 1 An embodiment of an apparatus 1 / process 1 for methanol synthesis comprising a reactor 10 according to the invention is shown.

[0079] A fresh synthesis gas stream (make-up gas stream) containing hydrogen and carbon oxides and inert components (e.g. methane) is introduced into the apparatus / process via conduit 12 and introduced via a reactant inlet (not shown) into a tubular reactor 15 arranged in the interior of a cylindrical shell 13. Prior thereto, a recycle gas stream containing unconverted synthesis gas components is supplied by conduit 14 and is likewise introduced into the tubular reactor 15 via conduit 12. Both the fresh synthesis gas and the recycle gas are compressed to reaction pressure and conveyed using a compressor (not shown) before being introduced into the tubular reactor 15.

[0080] In the tubular reactor 15, partial conversion of the synthesis gas components into methanol is achieved over a methanol synthesis catalyst under methanol synthesis conditions, releasing heat due to the exothermic nature of the reactions associated with methanol synthesis. The tubular reactor 15 is configured as a cylindrical single tube reactor and is filled with a catalyst active for methanol synthesis. Figure 1 The longitudinal coordinate z of the catalyst bed is indicated in . In the present example, the reactor 10 is in an upright arrangement.

[0081] Via conduit 16, a product mixture stream containing methanol, unconverted synthesis gas components and inert components is discharged from the tubular reactor 15 and the reactor 10 via a product outlet (not shown), cooled to a temperature below its dew point using a cooler 40, and introduced into a gas-liquid phase separator 50 via conduit 42.

[0082] In the gas-liquid phase separator 50, the product mixture stream is decomposed into a liquid crude methanol stream, which is discharged from the gas-liquid phase separator 50 via a conduit 52 and sent to a product post-processing device (not shown). The largest part of the unconverted synthesis gas is discharged from the gas-liquid phase separator 50 via a conduit 14 and, after compression, is sent back to the reactor 10 via a conduit 12. A smaller part of the synthesis gas is discharged from the device / process as a purge stream via conduit 14 and conduit 54 to prevent the accumulation of inert components.

[0083] The tubular reactor 15 is cooled using water as a coolant, which is supplied as a subcooled coolant flow via a pipe 32 and introduced via a coolant inlet (not shown) into an inner space 17 which is arranged between the outer wall of the tubular reactor 15 and the inner wall of the shell 13 and has an annular shape in this example.

[0084] When the gas flow of the reactant gas / product gas flows through the inner space 17 in countercurrent to the gas flow of the reactant gas / product gas, the coolant absorbs a portion of the reaction heat released by the methanol synthesis. Due to the upright arrangement of the reactor 10, the coolant flows through the inner space 17 from the bottom to the top. Due to the supercooling of the coolant by the cooler 30, the coolant remains liquid in the first cooling section of the tubular reactor, i.e., the last section of the catalyst bed, considering the reactant flow / product flow between the longitudinal coordinate 100% and the value of the longitudinal coordinate z between 0% and 100%. When flowing further through the inner space 17, the coolant begins to boil and undergoes complete or partial evaporation. The cooling of the upper region of the tubular reactor 15 on the second cooling section of the tubular reactor is therefore achieved by vaporizing the coolant or a two-phase flow of vapor and liquid. Considering the reactant flow / product flow between the longitudinal coordinate 0% and the value of the longitudinal coordinate z between 0% and 100%, the second cooling section of the tubular reactor 15 therefore corresponds to the first section of the catalyst bed.

[0085] The evaporated or partially evaporated coolant is discharged from the reactor 10 via the line 22 and introduced into the coolant reservoir 20 configured as a steam drum. A portion of the generated steam is sent to the consumer via the line 24. The coolant thus discharged from the cooling circuit is compensated by supplying a corresponding water flow as a coolant flow to the steam drum via a line (not shown). Liquid, steam-saturated coolant is discharged from the steam drum 20 via the line 26 and supplied to the cooler 30. The cooler 30 realizes a defined subcooling of the coolant, which is then recirculated to the reactor 10 via the line 32.

[0086] Numerical Example of Methanol Synthesis

[0087] Table 1: Water-cooled reactor, 2000 TPD methanol production. Reactor volume 88.8 m 3

[0088]

[0089] Explanation of symbols :

[0090] SN Stoichiometric number of methanol synthesis gas

[0091] Initial stage of SOR operation (initial stage of catalyst cycle)

[0092] EOR end of operation (end of catalyst cycle)

[0093] 6x4, 3x3 catalyst particle size

[0094] TPD (metric) tons / day

[0095] CO2 conversion rate of X_CO2_pp reactor in one pass

[0096] CO conversion rate per pass of X_CO_pp reactor

[0097] RR Recycle ratio of unconverted synthesis gas to the reactor LM Layer management, layers with different catalysts

[0098] Table 2: Water-cooled reactor, 2000 TPD methanol, layer management. Reactor volume 88.8 m 3

[0099]

[0100] As is evident from the data summarized in Table 1, subcooling the last 30% of the catalyst bed increases methanol production from 2190 TPD to 2206 TPD (SOR). The present invention alternatively makes it possible to reduce the recycle ratio from 3.2 to 2.85 while still maintaining the same methanol production. Figure 2 shows the accompanying temperature curve, where and Figure 3 and Figure 4 As in , the circular symbols correspond to the temperature in the reactor (in the catalyst bed) and the angular symbols correspond to the temperature of the coolant.

[0101] As is evident from the data summarized in Table 2, the use of catalyst layer management, i.e. the use of different catalyst layers (here two methanol synthesis catalysts of different particle sizes) together with subcooling of the coolant according to the invention, further increases the yield at a constant recirculation ratio. Figure 3The relevant temperature curve is shown in .

[0102] Table 3: Water-cooled reactor, CO-rich syngas, 2000 TPD methanol, layer management. Reactor volume 88.8 m 3

[0103]

[0104] As is apparent from the data summarized in Table 3, the relationships set forth in conjunction with Tables 1 and 2 apply not only to SOR, but also to EOR and process execution with Cl-rich syngas. Figure 4 The relevant temperature curve is shown in .

[0105] List of Reference Numerals

[0106] [1] Equipment / Method

[0107]

[10] Reactor

[0108]

[12] Pipeline

[0109]

[13] Housing

[0110]

[14] Pipeline

[0111]

[15] Tubular Reactor

[0112]

[16] Pipeline

[0113]

[17] Interior Space

[0114]

[20] Coolant reservoir (steam drum)

[0115]

[22] Pipeline

[0116]

[24] Pipeline

[0117]

[26] Pipeline

[0118]

[30] Cooler (heat exchanger or air cooler)

[0119]

[32] Pipeline

[0120]

[40] Cooler

[0121]

[42] Pipeline

[0122]

[50] Gas-Liquid Phase Separator

[0123]

[52] Pipeline

[0124]

[54] Pipeline

Claims

1. A reactor for carrying out an exothermic equilibrium reaction in which a fluid input mixed stream is at least partially reacted over a solid catalyst to provide a fluid product mixed stream, wherein the reactor comprises the following components in fluid connection with each other: (a) at least one tubular reactor or plate reactor, wherein the catalyst is arranged as a fluid-permeable catalyst packing of solid catalyst particles, wherein the catalyst is active for an exothermic equilibrium reaction within a reaction temperature range at a reaction pressure; (b) wherein the at least one tubular reactor or plate reactor is subjected to the reaction pressure and comprises a reactant inlet at one end thereof for the fluid input mixed stream and a product outlet at the other end thereof for the fluid product mixed stream; (c) a housing surrounding the at least one tubular reactor or plate reactor and being fluid-tightly sealed relative to the at least one tubular reactor or plate reactor at ends of the housing, wherein the housing has a coolant inlet and a coolant outlet at opposite ends of the housing for a flow of a fluid coolant; (d) wherein the inner space between the outer wall of the at least one tubular reactor or the outer wall of the at least one plate reactor and the inner wall of the shell is traversable by the coolant flow, wherein the coolant inlet and the coolant outlet are arranged so that the coolant flow passes through the reactor countercurrently to the input mixed flow and the product mixed flow; (e) a coolant for generating the coolant stream, wherein the coolant is selected such that it undergoes vaporization within the reaction temperature range at a specific coolant pressure; (f) a pressure control device for adjusting the coolant pressure in the internal space; (g) a coolant cooling device, which allows the coolant flow to enter the inner space in a liquid state via the coolant inlet, and initially flow through the inner space as a liquid and thereby cool the first cooling section of the at least one tubular reactor or plate reactor, then evaporate and cool the remaining second cooling section of the at least one tubular reactor or plate reactor in a vaporized state and / or as a two-phase flow of liquid and vaporized coolant, and then be discharged from the inner space in a vaporized state and / or as a two-phase flow of liquid and vaporized coolant via the coolant outlet.

2. The reactor according to claim 1, characterized in that The first cooling section of the at least one tubular reactor or plate reactor comprises the last section of the catalyst filling in the flow direction of the input mixed stream and the product mixed stream.

3. The reactor according to claim 1 or 2, characterized in that The final section of the catalyst packing comprises 0% to 30% of the total length of the catalyst packing, preferably 0% to 40% of the total length of the catalyst packing, most preferably 0% to 50% of the total length of the catalyst packing.

4. The reactor according to any one of claims 1 to 3, characterized in that The coolant cooling device is adjustable such that the temperature of the coolant flow before entering the interior space is at least 3°C, preferably at least 10°C, most preferably at least 20°C below the boiling temperature of the coolant at the coolant pressure.

5. The reactor according to any one of claims 1 to 4, characterized in that The reactor comprises a plurality of tubular reactors or plate reactors filled with a catalyst filling, which are arranged in parallel with respect to their longitudinal axes in the housing.

6. The reactor according to any one of claims 1 to 5, characterized in that The reactor is arranged upright relative to its longitudinal axis so that the reactant inlet and the coolant outlet are located at the upper end of the reactor, and the product outlet and the coolant inlet are located at the lower end of the reactor.

7. Use of the reactor according to any one of claims 1 to 6 for methanol synthesis and / or for ammonia synthesis.

8. A method for performing an exothermic equilibrium reaction wherein a fluid input mixed stream is at least partially reacted over a solid catalyst to provide a fluid product mixed stream, wherein the method comprises the steps of: (1) providing a reactor, the reactor comprising: (a) at least one tubular reactor or plate reactor, wherein the catalyst is arranged as a fluid-permeable catalyst packing of solid catalyst particles, wherein the catalyst is active for an exothermic equilibrium reaction within a reaction temperature range at a reaction pressure; (b) wherein the tubular reactor or plate reactor is subjected to the reaction pressure and comprises at one end thereof a reactant inlet for the fluid input mixed stream and at the other end thereof a product outlet for the fluid product mixed stream; (c) a housing surrounding the at least one tubular reactor or plate reactor and being fluid-tightly sealed relative to the at least one tubular reactor or plate reactor at ends of the housing, wherein the housing has a coolant inlet and a coolant outlet at opposite ends of the housing for a flow of a fluid coolant; (d) wherein the inner space between the outer wall of the at least one tubular reactor or the outer wall of the at least one plate reactor and the inner wall of the shell is traversable by the coolant flow, wherein the coolant inlet and the coolant outlet are arranged so that the coolant flow passes through the reactor countercurrently to the input mixed flow and the product mixed flow; (e) a coolant for generating the coolant stream, wherein the coolant is selected such that it undergoes vaporization within the reaction temperature range at a specific coolant pressure; (f) a pressure control device for adjusting the coolant pressure in the internal space; (g) a coolant cooling device, which enables the coolant flow to enter the inner space in a liquid state via the coolant inlet, and initially flow through the inner space as a liquid and thereby cool the first cooling section of the at least one tubular reactor or plate reactor, then evaporate and cool the remaining second cooling section of the at least one tubular reactor in a vaporized state and / or as a two-phase flow of liquid and vaporized coolant, and then be discharged from the inner space in a vaporized state and / or as a two-phase flow of liquid and vaporized coolant via the coolant outlet; (2) providing a fluid input mixture stream containing reactant components; (3) introducing the fluid input mixture stream into the at least one tubular reactor or plate reactor via the reactant inlet; (4) at least partially reacting the gaseous input mixed stream under exothermic equilibrium reaction conditions to provide a fluid product mixed stream comprising product components and unconverted reactant components; (5) discharging the fluid product mixture stream from the at least one tubular reactor or plate reactor via the product outlet.

9. The method according to claim 8, characterized in that The first cooling section of the at least one tubular reactor or plate reactor comprises the last section of the catalyst filling in the flow direction of the input mixed stream and the product mixed stream.

10. The method according to claim 8 or 9, characterized in that: The final section of the catalyst packing comprises 0% to 30% of the total length of the catalyst packing, preferably 0% to 40% of the total length of the catalyst packing, most preferably 0% to 50% of the total length of the catalyst packing.

11. The method according to any one of claims 8 to 10, characterized in that The coolant cooling device is adjustable such that the temperature of the coolant flow before entering the interior space is at least 3°C, preferably at least 10°C, most preferably at least 20°C below the boiling temperature of the coolant at the coolant pressure.

12. The method according to any one of claims 8 to 11, characterized in that The reactor comprises a plurality of tubular reactors or plate reactors filled with a catalyst filling, which are arranged in parallel with respect to their longitudinal axes in the housing.

13. The method according to any one of claims 8 to 12, characterized in that The reactor is arranged upright relative to its longitudinal axis so that the reactant inlet and the coolant outlet are located at the upper end of the reactor, and the product outlet and the coolant inlet are located at the lower end of the reactor.

14. The method according to any one of claims 8 to 13, characterized in that Steps (2) to (5) are configured as follows: (2) providing a gaseous input mixed stream containing hydrogen and carbon oxides as reactant components; (3) introducing the gaseous input mixed stream into the at least one tubular reactor or plate reactor via the reactant inlet; (4) at least partially reacting the gaseous input mixed stream under methanol synthesis conditions to provide a fluid product mixed stream comprising methanol as the product component and unconverted reactant components; (5) discharging the fluid product mixture stream from the at least one tubular reactor or plate reactor via the product outlet.

15. The method according to any one of claims 8 to 13, characterized in that Steps (2) to (5) are configured as follows: (2) providing a gaseous input mixed stream containing hydrogen and nitrogen as reactant components; (3) introducing the gaseous input mixed stream into the at least one tubular reactor or plate reactor via the reactant inlet; (4) at least partially reacting the gaseous input mixed stream under ammonia synthesis conditions to provide a gaseous product mixed stream comprising ammonia as the product component and unconverted reactant components; (5) discharging the gaseous product mixture stream from the at least one tubular reactor or plate reactor via the product outlet.

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