Reactor system for a carbonation method

Abstract

The invention relates to a reactor system (10) for a continuous carbonation method, having a plurality of at least ten tube reactors (12), which are arranged substantially vertically, for carrying out a carbonation reaction, wherein the tube reactors (12) can be operated under a pressure of ≥ 1, and the tube reactors (12) have at least one media inlet (18), through which a reaction mixture can be introduced into the tube reactors (12) which are under a pressure of ≥ 1. The reactor system (10) has a plurality of inlets (28) for introducing gaseous or supercritical carbon dioxide into the tube reactors (12), and the reactor system (12) has a separating unit for a material and / or phase separation of a reaction mixture flowing out of the tube reactor (12).

Description

[0001] Reactor system for a carbonation process

[0002] The present invention relates to a reactor system for a carbonation process. The present invention further relates to a carbonation process that can be carried out in such a reactor system. Furthermore, the present invention encompasses the use of such a process or such a reactor system for the production of paints, cement or cement substitutes, fillers, in particular for paper products, polymer products or for concrete, as well as products for road construction.

[0003] Carbon dioxide sequestration is a well-known process for removing carbon dioxide from the atmosphere or process gases and binding it chemically. Specifically, carbon dioxide sequestration involves, for example, ex-situ carbonation, in which a carbonation reactant or components thereof are subjected to a chemical reaction with carbon dioxide in an aqueous solution. This serves the primary purpose of removing carbon dioxide from industrial processes or the atmosphere and binding it chemically in a safe and long-term manner. Andreas M.Bremen, Till Strange, Hesam Ostovari, Hendrik Spütz, Adel Mhamdi, Phil Renforth, Mijndert van der Spek, Andre Bardow, and Alexander Mitsos, Direct Olivine Carbonation: Optimal Process Design for a Low-Emission and Cost-Efficient Cement Production, Industrial & Engineering Chemistry Research 2022 61 (35), 13177-13190, describes a process in which a carbonation reaction is carried out in a horizontal reactor.

[0004] DE 10 2021 116 491 A1 describes a carbonation process in which a carbonation reactant reacts with carbon dioxide in a reaction mixture, chemically binding the carbon dioxide. A key feature of this process is that at least one nucleating agent is added to the reaction mixture, on which at least one resulting reaction product deposits. The nucleating agent comprises at least one material that is a reaction product of the carbonation reactant with carbon dioxide.

[0005] WO 2021 / 009385 A1 describes a process for carbonating carbon dioxide, in which in particular a threefold or double reduction or ideally a threefold or double avoidance of carbon dioxide emissions is to be achieved, namely by capturing the carbon dioxide generated from the air or during the production of molecular energy carriers in solids and, furthermore, by avoiding carbon dioxide emissions by using these solids as a replacement for construction and / or chemical materials whose conventional production process traditionally leads to carbon dioxide emissions.

[0006] EP 2457638 A1 describes a plant and method for treating CO2 from a CCL-emitting industrial plant, comprising a CCl filter installed in a duct or other chamber through which, during operation, a stream of CCl-containing gases from the industrial plant flows, and which can operate with or without a vacuum. More specifically, the CCl filter consists of plates or other bodies or pieces, or of gravel or another particulate or crushed form of peridotitic mafic igneous rock or a material of similar chemical composition, selected, for example, from basalt, gabbro, dunite, and amphibolites, or of artificially produced materials based on Ca and Mg oxides with a similar chemical composition and similar properties to the listed naturally occurring mafic igneous rock materials.

[0007] WO 2014 / 082996 A1 describes a process for producing a second composition, the process comprising the following steps: preparing a first composition containing an alkali metal magnesium orthosilicate and optionally either (i) magnesium oxide or (ii) an alkali metal silicate; and contacting the first composition with water to produce the second composition containing an amorphous magnesium silicate hydrate (MSH). In one embodiment, an alkaline solution produced in the process is contacted with a carbon dioxide-containing gas, e.g., combustion exhaust gases, to absorb carbon dioxide and obtain an alkali metal carbonate, alkali metal bicarbonate, or a mixture thereof, generally in solution, and (precipitated) silicon dioxide.

[0008] WO 2011 / 035047 A2 describes a process for increasing the activity of a hydrous magnesium silicate mineral with respect to mineral carbonation, the process comprising thermal shock treatment of the mineral by very rapid heating. According to this document, it has been proven possible to increase the activity of a specific class of starting material with respect to mineral carbon dioxide carbonization by heat treating the mineral according to a specific heat treatment regime. Accordingly, rapid heating (thermal shocking) of a hydrous magnesium silicate mineral leads to modifications of the mineral, resulting in increased activity with respect to mineral carbon dioxide carbonation. In this context, the increase in activity refers to the mineral that has not been subjected to such heat treatment.

[0009] EP 2718230 B1 describes a process for mineralising carbon dioxide to form a magnesium carbonate compound, which process comprises contacting the carbon dioxide in free form or in the form of an alkali metal carbonate or bicarbonate with an alkali metal magnesium silicate to produce the magnesium carbonate compound.

[0010] US 2009 / 0305378 A1 describes a process for carbonizing minerals, characterized in that the silicate feedstock is thermally activated using heat generated by the combustion of fuel before reacting the activated slurry feedstock with carbon dioxide.

[0011] WO 2010 / 022468 A1 describes a process for converting carbon dioxide into solid material, the process comprising the following steps: (a) direct thermal activation of mineral magnesium silicate hydroxide feedstock by combustion of fuel to produce an activated feedstock; (b) separation of metal oxides, at least substantially excluding magnesium oxide and magnesium silicate, from the activated feedstock to produce a residual activated feedstock; (c) before or after the separation step, suspending the activated feedstock in a solvent to form a slurry; and (d) contacting the slurry of the residual activated feedstock with carbon dioxide to convert the carbon dioxide to magnesium carbonate.

[0012] WO 2011 / 155830 A1 describes a process for converting metallic silicate minerals into silicon compounds and metal compounds by means of a conversion reaction, which is characterized in that the conversion reaction is carried out in a gravity pressure vessel (GPV), wherein: the gravity pressure vessel comprises two channels with separate inlets on the top side of the gravity pressure vessel, wherein the channels are interconnected on the bottom side of the gravity pressure vessel, and wherein the process comprises the following steps: providing a dispersion of solid particles of silicate minerals in water; conveying the provided dispersion through a first channel of the GPV in a descending direction so that a descending dispersion flow is obtained in the first channel;Reacting the solid particles of silicate minerals in the dispersion with one or more reactants by adding the reactants to the descending dispersion stream; and discharging the silicon compounds and metal compounds formed during the conversion reaction through a second channel of the GPV in an ascending stream. Surprisingly, it has been found that an efficient and energy-saving conversion reaction with other additional advantages is achieved by using a gravity pressure vessel (GPV) and reacting the descending stream of silicate minerals with added reactants in the GPV.

[0013] Document US 2016 / 0166985 A1 describes an air purification process that specifically aims to remove carbon dioxide from the air or reduce its concentration. The reduction of carbon dioxide is carried out using microalgae.

[0014] Such solutions known from the prior art may still have potential for improvement, particularly with regard to improved sustainability. Therefore, the object of the present invention is to provide a measure by which at least one problem of the prior art is at least partially overcome. In particular, it is an object of the present invention to provide a measure by which a carbonation process can be improved, particularly with regard to its sustainability.

[0015] The object is achieved according to the invention by a reactor system having the features of claim 1. The object is further achieved according to the invention by a method having the features of claim 12 and by a use having the features of claim 14. Preferred embodiments of the invention are disclosed in the subclaims, in the description, and in the example, wherein further features described or shown in the subclaims or in the description or the example can represent an object of the invention individually or in any combination, unless the context clearly indicates the opposite.

[0016] A reactor system for a continuous carbonation process is described, comprising a plurality of substantially vertically arranged tubular reactors for carrying out a carbonation reaction, wherein the tubular reactors are operable under a pressure of > 1 bar and wherein the tubular reactors have at least one media inlet through which a reaction mixture can be introduced into the tubular reactors which are under a pressure of > 1 bar, wherein the reactor system has at least one inlet for introducing carbon dioxide into the tubular reactors; and wherein the reactor system has a separation unit for material and / or phase separation of a reaction mixture flowing out of the tubular reactor.

[0017] Such a reactor system allows in a particularly advantageous manner the carbonation of a suitable reactant and thus the removal of carbon dioxide from process gases and from the atmosphere and, in particular, the permanent storage of the carbon dioxide in the reaction product of the carbonation process.

[0018] The reactor system described here thus serves a carbonation process and can be used in particular in a process for sequestering carbon dioxide. For the purposes of the present invention, such a process is understood in particular to mean a process in which carbon dioxide reacts with a carbonation reactant or a component thereof and can thus be bound in chemical form. Sequestration thus serves in particular to remove carbon dioxide from the atmosphere or a gas in general or to prevent its entry and, in particular, to store it permanently in chemically bound form. The process, which can be carried out in the reactor, thus comprises carbonation, such as mineral ex-situ carbonation, of the carbonation reactant.

[0019] The reactor system comprises a plurality of essentially vertically arranged tubular reactors for carrying out a carbonation reaction. At least two, for example at least ten, or even at least fifty tubular reactors can be provided. A substantially vertical arrangement of the reactors should be understood in particular to mean that they are arranged exactly vertically or in such a way that a gas can flow through the tube of the reactors only due to buoyancy. The vertical arrangement of the reactors also makes it possible to avoid sedimentation of the solid particles contained in the flowing suspension. For example, an essentially vertical orientation can thus be an exactly vertical orientation with a maximum deviation of 60°, for example with a maximum deviation of 45°, for example with a maximum deviation of 15° from the vertical.In particular, for a space-saving arrangement, all tubular reactors, or at least a large portion of them (e.g., at least 75%, at least 90%), can be arranged in parallel. This makes it possible for the material flow to enter one side of the tubular reactor, flow along the axis, and exit the tubular reactor again on the opposite side.

[0020] For example, at least ten, for example at least fifty, for example at least one hundred tubular reactors may be provided.

[0021] Furthermore, the tubular reactors are preferably suitable for high-pressure reactions and can be operated at a pressure of > 1 bar, approximately > 20 bar, preferably > 50 bar, and particularly preferably > 100 bar. This is advantageous because, in particular, a carbonation reaction is effectively possible at high pressure and allows for high conversion. The essentially vertically arranged tubular reactors ensure good phase mixing of the solid, liquid, and gas phases, as phase separation is prevented by the parallel flow direction and gravitational force as the driving force for sedimentation. Mixing can be further improved by static mixers arranged in the reactors.

[0022] The tubular reactors have at least one media inlet through which a reaction mixture can be introduced into the tubular reactors, which are under a pressure of > 1 bar. Accordingly, the reaction mixture can be introduced into a reactor if the reactor is under a pressure of > 1 bar, since this allows for a continuous process. In particular, the reaction mixture can be introduced into a reactor under operating pressure. By providing a plurality of tubular reactors, it can be ensured that a homogeneous pressure level prevails in the reactors, even in a vertical arrangement, which in turn can allow for a defined reaction.

[0023] Where the media inlet(s) is / are located can be chosen depending on how the tubular reactors are connected. With a parallel connection, each of the reactors can have a media inlet for introducing the reaction mixture, whereas with a serial connection only one reactor needs to have a corresponding initial media inlet, since the reaction mixture can then flow through the other reactors, starting from the first reactor that has the media inlet. In principle, however, the number of media inlets can be selected, so that, for example, even with a serial connection, several or even each of the reactors can have a media inlet. Furthermore, further media inlets can also be provided at intervals of a certain reaction section and thus after a possible reaction time.

[0024] However, it is advantageous for the media inlet and media outlet on at least one, preferably on all, tubular reactors to be selected such that the reaction medium can flow at least partially, preferably completely, through the respective tubular reactor, which, with regard to the vertical arrangement, can be possible in a direction from bottom to top or from top to bottom. For example, a media inlet can be located in a bottom region, for example at the bottom, of the respective tubular reactor, and a media outlet can be located in a top region, for example at the top of the respective tubular reactor. The bottom region is the region in the lower half, for example in the lower third, preferably in the lower tenth, approximately at the lowest point, of the tubular reactor.Correspondingly, the head region is the area located in the upper half, for example, in the upper third, preferably in the upper tenth, approximately at the topmost point, of the tubular reactor. This makes it possible for a mixture of the reactant or product, such as a suspension, to be passed through the respective tubular reactor, thus forming the entire tubular reactor as the reaction volume. For this purpose, appropriate conveying means, such as pumps, are provided to convey the mixture.

[0025] In addition, the reactor system has at least one inlet for introducing

[0026] Carbon dioxide, in particular in the gaseous or supercritical state, is introduced into the tubular reactors. In this regard, the number and position of the inlets can again be selected. For example, only one inlet can be provided or there can be a plurality of inlets with a fundamentally selectable position. In principle, however, it is important for the purposes of the present invention that the inlet is positioned such that the inlets are positioned such that carbon dioxide can flow upwards through the tubular reactors. For this purpose, the inlet or inlets can be arranged, for example, in the lower half, for example in the lower third, of the tubular reactors. In a serial connection, the inlets can also be arranged, for example, between two reactors and be entrained with the reaction mixture. The inlets can, for example, be designed in the form of nozzles.They can either be permanently installed or be replaceable or interchangeable and thus renewable in the event of wear or clogging.

[0027] Introducing carbon dioxide can mean introducing pure carbon dioxide, for example, or introducing a correspondingly diluted or contaminated carbon dioxide. For example, carbon dioxide can be introduced in a mixture, such as a gas mixture, which contains at least 50 wt.%, such as at least 75 wt.%, carbon dioxide, for example at least 90 wt.%.

[0028] It is further provided that the reactor system has a phase separator for phase separation of a reaction mixture flowing out of the tubular reactor, for example for separating the solid or components thereof from the reaction mixture flowing out of the tubular reactor. This allows reacted material, i.e. the reaction product, to be removed from the process stream, thus particularly advantageously enabling the process stream to be recycled by recirculating unseparated components of the reaction medium. In principle, the material separation or phase separation can be carried out by the separation unit by performing a unit operation, such as using filters, hydrocyclones, classifying centrifuges, or a combination of several unit operations. For example, the separation unit can accordingly comprise a filter for filtering the reaction mixture or a gas / liquid phase separator.

[0029] The reactor system described here has significant advantages over state-of-the-art solutions.

[0030] In particular, a substantially vertical arrangement of the reactors can enable a particularly efficient reaction. Dead volumes, in which gas accumulates but no reaction takes place, can be prevented or at least significantly reduced. At the same time, a large reaction volume can be enabled. Accordingly, essentially the entire reactor volume can be used for the reaction.

[0031] Furthermore, a very defined reaction can take place because the reaction volume can be determined very precisely, thus minimizing any disruptive factors that could negatively influence the reaction. Furthermore, the vertical arrangement prevents the significantly heavier solid particles from settling, which in turn leads to good mixing and an efficient reaction. A further advantage of the vertical arrangement is that the introduced CO2 flows in the form of bubbles either cocurrent or countercurrent to the main flow and does not rise perpendicular to it as in the horizontal arrangement. This allows for a comparatively long flow path of the carbon dioxide through the reactor, which in turn permits a very efficient reaction.

[0032] Finally, the reactor system, thanks to its large number of tube reactors, particularly those arranged vertically, allows for the simple interconnection of multiple reactors, which in turn can allow for a very high reaction rate within a relatively compact volume. Thus, the reactor system described here provides a highly adaptive and efficient system for carrying out a carbonation reaction.

[0033] A further advantage is that, especially with a large number of tubular reactors, the temperature removal or heat removal to maintain the reaction temperature can be controlled very efficiently and precisely. This further improves the ability to provide defined reaction conditions and thus carry out the reaction as desired and efficiently.

[0034] Accordingly, a carbonation reaction with low energy input, high reaction conversion of carbon dioxide and at the same time minimal volume is enabled, thus improving sustainability.

[0035] Preferably, the reactor system can comprise tubular reactors with different diameters, or the reactor system can comprise at least one tubular reactor with a diameter of varying size. This configuration can have a beneficial effect on the carbonation reaction taking place. It has been found that the reaction is promoted when the system is temporarily vigorously mixed and then calmed down again. In a continuous tubular system with a constant volume flow, this is achieved in this configuration by a change in the diameter or cross-section, which increases or decreases the flow velocity and thus the turbulence, respectively. This configuration can therefore have a beneficial effect on the solubility of the reactants or the products, both as a solid or as a gaseous substance. Furthermore, a slow flow can promote the crystal growth of the carbonates.In principle, the diameter of the tubular reactors can be in a range from > 32 mm to < 500 mm, for example in a range from > 100 mm to < 250 mm, whereby the diameter refers to the inner diameter, i.e. the active reaction volume.

[0036] In principle, this is possible both by using a tube reactor with a varying diameter and by using different tube reactors with different diameters.

[0037] Preferably, the reactor system downstream of the phase separator can be operated at a pressure of > 1 bar. In this embodiment, the region downstream of the phase separator or the unit operation, i.e., purely by way of example, the low-pressure side of the filter, can thus also be operated at a pressure that is above atmospheric pressure. This embodiment advantageously allows for the implementation of a recirculation system, so that the recirculated reaction mixture can be easily fed back into the process. In particular, the reaction mixture can be recycled to one or more reactors. Exemplary pressures suitable for the operation of the region downstream of the phase separator, i.e., for example, between the phase separator and the tubular reactor, are approximately in a range of greater than or equal to 1 bar, approximately greater than or equal to 50 bar, preferably greater than or equal to 5 bar below the pressure in the tubular reactor.

[0038] It may further be preferred for the phase separator to allow particles to pass through that have a size in the range of < 10 pm, for example < 3 pm, for example < 1 pm. This configuration allows particles that have a positive influence on the reaction process in a defined manner to be returned to the reaction process. The values ​​mentioned are only to be considered as examples. In detail, it should be noted that after formation, the reaction products of carbonation usually also settle on the surface of the carbonation reactant. This leads to the formation of a passivation layer that increasingly hinders the reaction of the carbonation reactant with carbon dioxide, for example by making it more difficult or preventing the corresponding cations from being released from the carbonation reactant. This limits the reaction conversion of the carbonation reactant.

[0039] By recycling the particles of a defined size passing through during phase separation, reaction products from the carbonation reaction, such as corresponding carbonates or amorphous silicon dioxide, are primarily deposited on the surface of the particles serving as nucleating agents, while the particles of the carbonation reactant remain essentially free of these. Accordingly, improved reaction control with reduced inactivation is possible.

[0040] The described design thus enables a particularly high reaction conversion of the carbonation reactant. In particular, it can effectively prevent the formation of a passivation layer on the surface of the particles of the carbonation reactant from ending the reaction without the reaction conversion being well advanced or even complete. It has been shown that particles in the aforementioned size range, in particular, are effective as precipitation carriers for the products of the carbonation or sequestration reaction. This can be due in particular to the fact that the small particle size results in a high specific surface area, which results in effective nucleation. Furthermore, such small particles in particular can ensure that no damage is caused to the coated nucleating agents during the reaction, which further simplifies the process.It may further be preferred to provide a comminution unit by which a solid starting product can be comminuted before being introduced into the tubular reactor. This allows the starting products to be brought to a size suitable for the reaction directly in the reaction system and fed to the reaction through the media inlet. Suitable sizes include approximately <100 pm, for example <20 pm. Furthermore, a comminution unit may comprise, for example, a cone crusher or a ball mill; wet grinding may be used; or other comminution units, such as roller mills or pendulum mills, may be used.

[0041] Preferably, the tubular reactors can be part of a recirculating system. This allows a continuous process to be carried out particularly efficiently. Furthermore, as described above, reaction products can have a positive effect on the process, for example as nucleating agents.

[0042] It may further be preferred for the reactor system to comprise at least one processing unit for mechanically processing solids present in the reaction stream, wherein the processing unit is arranged between two tubular reactors. Such a processing unit can subject existing solids to mechanical stress. This configuration takes into account the fact that product material can settle on the surfaces of the reactant particles during the carbonation reaction. A passivation layer thus formed on the reactant particles prevents a complete reaction or at least significantly reduces the reactivity. The passivation layer can also be formed by non-stoichiometric dissolution of the reactant, i.e., the leaching of alkaline earth metals, so that a SiO2-rich layer inhibits further dissolution, since the dissolution reaction is then diffusion-limited.A mechanical intermediate treatment breaks down the passivation layer and achieves a higher reaction conversion. This can be achieved using any device that mechanically acts on the particles, such as a gear pump. This would also have the synergistic effect of promoting the product flow, which can simplify the setup.

[0043] Further preferably, a sensor for detecting gaseous components can be provided in the tubular reactor. In this embodiment, at least one of the fill level of the aqueous mixture in the tubular reactor and the gas concentration in the aqueous mixture can be detected. Such a sensor can be used, in particular, to monitor the ongoing reaction. This is because a sensor for detecting the fill level can be used to determine the level of the liquid or suspension and solid, or the size of a potentially building up gas volume at the top of the reactor. This can build up, for example, from unreacted carbon dioxide, water vapor, or inert gases present in the gas. Thus, in this embodiment in particular, the aforementioned advantages with regard to a large reaction volume and a minimized dead volume can be ensured.Furthermore, by determining the gas concentration in the aqueous mixture, for example, it can be determined whether sufficient gas is present to carry out the reaction as desired. An optimal value can be the saturation concentration, so that no gas bubble forms but a maximum amount of carbon dioxide is present in the aqueous phase. Suitable sensors in this embodiment include, for example, sensors for determining the density, conductivity, substance concentration or pH value in the medium. The values ​​determined in this way can be used to regulate the incoming volume flow of carbon dioxide. Optionally, the carbon dioxide detected as a gas bubble at the high points or at the head regions of the tubular reactors can be returned to the process, if present.

[0044] Particularly advantageous sustainability can be achieved if the heat generated in the tubular reactor can be reused at another point in the process. This is easily possible, for example, using appropriate heat exchangers that transfer the heat generated in the tubular reactors to other locations. For example, heat transfer media can flow around the reactors and be directed to locations where the heat is needed. For example, reactant streams can be preheated to make the process particularly sustainable with low energy consumption, or products can be dried.

[0045] In particular in this embodiment, it may be advantageous that at least one tubular reactor, preferably all existing tubular reactors, is equipped with a temperature control unit, wherein the temperature control unit has a fluid guide for guiding fluid temperature control medium, which runs on the outer circumference of the at least one tubular reactor.

[0046] In detail, a temperature control unit in a tubular reactor system enables very good and precise temperature control. A heat transfer medium, such as air, water, thermal oil, etc., flows through the fluid line. For this purpose, a control system is arranged around the tubular reactors. For example, the tubular reactors are enclosed in a jacket as a fluid guide, and the jacket has one or more inlets and outlets for the heat transfer medium. With optional baffles, the heat transfer medium can be guided along the tubes. The advantage is that an ideal and as homogeneous as possible temperature prevails throughout the entire reactor. This homogeneous temperature is primarily achieved by the fact that the numerous tubular reactors have a very high specific surface area, which enables very good heat transfer.The fluid heat transfer medium can be heated via external heat supply, for example during reactor start-up, and cooled during operation to dissipate the exothermic heat during the reaction. The latter can be particularly advantageous for the heat recovery described above. It can further be provided that upstream of the separation unit, at least one of an expansion unit for at least partially expanding the process stream and a gas separator, in particular for separating gas present in the process stream and / or for absorbing pressure fluctuations or pressure peaks, is provided. In this embodiment, it is possible to prevent gas present in the process stream, such as carbon dioxide, carrier gas, or even water vapor, from being entrained. On the contrary, such gas can be effectively removed from the process stream.For example, carbon dioxide can be isolated from a gas mixture and fed back into the reaction, or the removed gas can be returned to the process without further purification. Suitable and known gas separators or expansion units can be used for this purpose.

[0047] For example, the majority of tubular reactors can be connected in series. This allows the reaction mixture to pass through all of the reactors. This configuration allows for a particularly long reaction time and thus an effective reaction.

[0048] It is also possible to connect the majority of tubular reactors in parallel. In this configuration, a comparatively large amount of carbon dioxide can be converted in a short time.

[0049] According to the invention, it may be possible for the reactor system to be designed in such a way that switching between parallel and serial connection and vice versa is possible. This is possible in a conventional manner using appropriate connection units.

[0050] With regard to further technical features or advantages of the reactor system, reference is made to the description of the carbonation process, the use, the figures, and the description of the figures, and vice versa. Furthermore, a continuous carbonation process is described, comprising the process steps: a) providing a carbonation reactant, wherein the carbonation reactant is suitable for reacting with carbon dioxide; b) providing carbon dioxide, in particular in a gaseous or supercritical state; and c) reacting the carbonation reactant with carbon dioxide with chemical bonding of the carbon dioxide, wherein process step c) is carried out in a reaction system described above.

[0051] The process described here is a carbonation process and can be used in particular in a process for sequestering carbon dioxide or can represent this. For the purposes of the present invention, such a process is understood in particular to be a process in which carbon dioxide reacts with a carbonation reactant or a component thereof and can thus be bound in chemical form. Sequestration therefore serves in particular to remove carbon dioxide from process gases or the atmosphere or, in principle, from a gas and to store it in a chemically bound form, in particular permanently. The process thus comprises carbonation, such as mineral ex-situ carbonation, of the carbonation reactant.

[0052] For this purpose, the process according to process step a) comprises providing a carbonation reactant, wherein the carbonation reactant is suitable for reacting with carbon dioxide. A reaction of the carbonation reactant with carbon dioxide is understood, in a manner understandable to the person skilled in the art, within the meaning of the present invention to mean that the carbonation reactant as a whole or parts thereof can react with carbon dioxide to chemically bind carbon dioxide. For example, individual ions contained in the carbonation reactant, in particular cations, can react with carbon dioxide and, for example, form the corresponding carbonates.

[0053] Thus, the carbonation reactant can in principle be freely selected and is not fundamentally limited, as long as a reaction with carbon dioxide can be enabled as described above.

[0054] However, it may be preferred that the carbonation reactant comprises at least one material selected from the group consisting of oxides and silicates of alkali metals and alkaline earth metals, in particular calcium- or magnesium-containing solids. Such carbonation reactants are particularly well suited to binding carbon dioxide, since the metal cations are usually readily soluble and, furthermore, a reaction to form the corresponding carbonates or amorphous silicon dioxide is effectively possible. Furthermore, these materials are usually readily available, either as minerals or rocks, such as peridodites, olivines, basalt, and materials from the serpentine group, or as secondary raw materials, such as slags, fly ash, filter dust, and mining waste or processing tailings.

[0055] In principle, however, any material known from the state of the art for carbonation can be used.

[0056] The carbonation reactant can also be mixed, in particular, with a liquid carrier, such as water, before being fed to a reaction. For this purpose, a mixer with a high-pressure metering unit can be provided, through which the reactant or reactant stream can be fed to a reaction, such as a reactor. Furthermore, additives such as NaCl, NaHCCE, NaOH, and / or organic acids or bases can be added.

[0057] According to process step b), the process described here further comprises the provision of carbon dioxide, in particular in a gaseous or supercritical state. Carbon dioxide can be provided in a suitable purity so that it can be introduced into a reactor in which the carbonation reaction is carried out. For example, the carbon dioxide can be provided in gaseous form in a carrier gas, such as in particular an inert gas, for example argon or nitrogen. The carbon dioxide can be present in the gas mixture in a proportion of > 15 wt.% to < 100 wt.% and can be fed to the reaction. For example, carbon dioxide can be used in a content of at least 50 wt.%, for example at least 75 wt.%, for example at least 90 wt.%.

[0058] Accordingly, the process comprises the further process step c), namely carrying out a reaction of the carbonation reactant in a reaction mixture with carbon dioxide under chemical bonding of the carbon dioxide. For example, the carbon dioxide can be added to the reaction mixture in a targeted manner so that it comes into contact with the carbonation reactant or the reactive components thereof. For this purpose, the reaction mixture can be present under an excess pressure of carbon dioxide. It is preferred that the reaction mixture comprising the solid reactant or product ideally flows essentially completely through the tubular reactors, whereby the gas can be conducted in cocurrent or countercurrent.

[0059] For example, as is known from the prior art, the reaction mixture can be an aqueous mixture, such as a dispersion, to which the carbonation reactant is added and in which cations of the carbonation reactant dissolve. In particular, alkali metal or alkaline earth metal cations from the carbonation reactant can dissolve in order to react with the carbon dioxide.

[0060] This is possible, for example, by using an aqueous reaction mixture and adding an acid or base so that the pH of the aqueous mixture is adjusted accordingly. In principle, one or more acids and / or one or more bases and / or one or more chelating agents can be added to the reaction mixture, although the addition of further additives is not excluded. In addition, further parameters, such as a suitable reaction temperature and / or a suitable partial pressure of carbon dioxide, can be adjusted so that carbonation takes place with the formation of corresponding reaction products within an economically reasonable timeframe. The adjustment of such parameters as well as the basic implementation of such a carbonation is generally known to the person skilled in the art.

[0061] An exemplary and non-limiting reaction equation of a carbonation reaction that can take place in the sense of the present invention corresponds to the following equation:

[0062] Me x SiO 2+x + xCO2-* xMeCO3+ SiO2, where Me is an alkali or alkaline earth metal and where x represents the number of respective atoms in the chemical compound, so that x depends on the carbonation reactant used in a manner understandable to the person skilled in the art.

[0063] According to the invention, the process described above is carried out in a reactor system as described above. This essentially results in the advantages as described above with reference to the reactor system. Reaction product obtained after process step c) can preferably be removed from the reaction system by means of a separation unit, with particles up to a defined size range being reused in process step c) as a component of the material stream downstream of the separation unit, for example a filtrate. For example, particles which have a maximum size in a range of < 3 pm can be recycled. These can serve particularly advantageously as nucleating agents in the reaction and thus have a positive influence on the reaction.

[0064] In detail, the process described here can enable a particularly efficient and sustainable reaction with a high reaction conversion.

[0065] For further technical features or advantages of the carbonation process, reference is made to the description of the reactor system, the use, the figures and the description of the figures, and vice versa.

[0066] The invention further describes the use of a process or reactor system as described above for producing cement or cement substitutes, fillers, particularly for paper products, polymer products or concrete, or products for road construction. It has been shown that the advantages of the invention are particularly effective in the production of such products. Thus, the CCE footprint can be significantly reduced, especially in the production of such products.

[0067] For further technical features or advantages of use, reference is made to the description of the reactor system, the carbonation process, the figures, and the description of the figures, and vice versa. The invention is explained below by way of example with reference to the accompanying drawings. The features presented below may represent an aspect of the invention, both individually and in combination. The invention is not limited to the following drawings, the following description, and the following exemplary embodiment.

[0068] It shows:

[0069] Fig. 1 is a schematic view of a reactor system according to an exemplary embodiment of the present invention.

[0070] Figure 1 shows a reactor system 10 for a continuous carbonation process. The reactor system 10 comprises a plurality of essentially vertically arranged tubular reactors 12, which, in the embodiment according to Figure 1, are connected in series by interposed connecting regions 14, which can be designed, for example, as pipelines or U-shaped tubes. The tubular reactors 12 can be operated at a pressure of > 1 bar in order to achieve a favorable reaction conversion, as described in more detail below. Sensors 16 for detecting gaseous components in the tubular reactor 12 are provided at the head-end connecting regions 14.

[0071] A media inlet 18 is provided on the first tubular reactor 12 in the flow direction, through which a reaction mixture can be introduced into the tubular reactors 12 which are under a pressure of > 1 bar.

[0072] To introduce the reaction mixture, a rock mill is provided as a comminution unit 20, through which a reactant can be comminuted. The reactant, such as an oxide of an alkaline earth metal, can be mixed with water and additives and introduced into the reactors 12 by a high-pressure dosing unit 22, such as a piston pump, press, or screw. The introduction of the raw reactant is indicated by arrow 24, and the introduction of the aqueous phase, optionally containing additives, is indicated by arrow 26.

[0073] The reactor system 10 further comprises a plurality of inlets 28 for introducing, in particular, gaseous or supercritical carbon dioxide into the tubular reactors 12. According to Figure 1, these inlets 28 are arranged at connecting regions 14 located at the bottom of the tubular reactors 12. Alternatively, the inlets 28 can also be arranged directly on the tubular reactors 12. The approximately gaseous carbon dioxide can be taken from a carbon dioxide source 30, such as a pressure vessel, and supplied to the tubular reactors 12 or the inlets 28, such as nozzles, by a compressor 32 or a pump. In addition to supplying CO2, the inlets 28 optionally serve to supply additives, such as acids and bases, to provide CO2 for the reaction and to adjust the pH of the aqueous solution to the reaction requirements.

[0074] A processing unit 56 for mechanically processing solids present in the reaction stream is also provided between two tubular reactors 12. This unit can break up passivation layers on the particles, which can further increase reactivity. Furthermore, comminution of particles, both reactant and product particles, can act as additional nucleating agents.

[0075] It is also apparent from Figure 1 that the process stream can be circulated. For example, in such a circuit, the reaction mixture before the reaction as well as the mixture after the reaction or the material stream in the circuit can be referred to as the process stream. To advantageously enable this and in particular to remove reaction products or residues of the reactant from the material stream, a separation unit (34) is provided which serves for material separation and / or phase separation. Accordingly, the separation unit can enable at least one operation of material separation and phase separation. Accordingly, a material separation of the reaction product and the reaction medium of a reaction mixture flowing out of the tubular reactor 12 can be enabled.The separation unit 34 is based, for example, on a material separation through a unit operation or a combination of several unit operations, such as filtration using a high-pressure filter, vacuum filter, drum filter, a tubular press, a hydrocyclone, or a classifying centrifuge. Furthermore, the reactor system 10 downstream of the separation unit 34 can be operated under a pressure of > 1 bar. Furthermore, the separation unit 34 can allow particles with a size in the range of approximately < 10 pm to pass through. Smaller particles remain partially in the aqueous solution and thus form a suspension. These particles consist of unreacted reactant and product particles, which can serve as nucleating agents after recycling in the reaction.

[0076] In principle, for example, a plurality of unit operations for phase separation and / or material separation of the separation unit 34 can be connected in parallel, which are then active sequentially to remove or clean the solids during inactive unit operations. This enables a more economical process due to lower energy consumption for heating and compressing recirculated process streams. The separated solids can be discharged, as indicated by arrow 36. The remaining reaction medium can be fed back to the media inlet 18, for example, via a feed pump 38.

[0077] Furthermore, a gas separator 40 is provided upstream of the separation unit 34.

[0078] For example, gas separator 40 serves to separate gas present in the process stream. Furthermore, a gas separator can be advantageous because it can make it possible to keep the pressure in the system stable, for example, by creating a gas cushion. This can prevent pressure fluctuations and pressure surges.

[0079] Furthermore, Figure 1 shows that heat generated in the tubular reactors 12 can be reused elsewhere in the process. This is made possible by the provision of a plurality of heat exchangers. This offers the significant advantage that the heat generated by the exothermic chemical process can be dissipated via the large surface area of ​​the tubular reactors 12, thus ensuring constant reaction conditions along the entire length. The heat can be absorbed by a heat transfer medium, such as air, water, oil, etc., and reused elsewhere in the process.

[0080] Heat exchanger 44 is optional; the heat transfer medium can also come into direct contact with other heat transfer devices, such as heat exchangers. Furthermore, it is possible to cool the process medium upstream of the separation unit 34, for example, using heat exchanger 46, and to utilize the heat generated during carbon dioxide compression, for example, via heat exchangers 48, 50. This heat output, as well as the heat output of the tubular reactors 12, can be used to preheat the feedstock, in particular comprising rock, water, and additives, for example, using heat exchangers 52, 54, or to dry the separated product material.

[0081] The reactor system 10 shown thus essentially comprises continuously operated tubular reactors 12, which operate at high pressure and temperature, as well as peripheral equipment that selectively feeds and discharges media from the reactor under reaction conditions, as well as grinds, separates, conveys, compacts, compresses, separates, and mixes them. The chemical reaction of gaseous CO2 to solid carbonate (CO2 mineralization, for example, on magnesium- or calcium-containing solids) that can be carried out here can be carried out very efficiently and sustainably. The possible continuous operation saves time, as the setup times of a batch process are eliminated, and it also saves energy, as energy expenditure for adjusting the required pressure and temperature is not necessary for each reaction run.The energy-efficient process described here, executable in the reactor system 12 according to the invention, makes it possible to cost-effectively produce a product such as paints, cement or cement substitutes, fillers, particularly for paper products, polymer products or concrete, or products for road construction while simultaneously minimizing the CO2 emissions of the mineralization process. For example, the present invention makes it possible to significantly reduce the CO2 footprint in cement by using the produced material, for example, as a substitute in cement.

[0082] Reference symbol

[0083] 10 reactor system

[0084] 12 tube reactor

[0085] 14 Connection area

[0086] 16 Sensor

[0087] 18 Media entrance

[0088] 20 shredding unit

[0089] 22 High-pressure dosing unit

[0090] 24 Arrow

[0091] 26 Arrow

[0092] 28 Entrance

[0093] 30 Kohl endi oxi dquell e

[0094] 32 compressors

[0095] 34 Separation unit

[0096] 36 Arrow

[0097] 38 feed pump

[0098] 40 gas separators

[0099] 42 Arrow

[0100] 44 heat exchangers

[0101] 46 heat exchangers

[0102] 48 heat exchangers

[0103] 50 heat exchangers

[0104] 52 heat exchangers

[0105] 54 heat exchangers

[0106] 56 processing unit

Claims

Patent claims 1. Reactor system (10) for a continuous carbonation process, comprising a plurality of substantially vertically arranged tubular reactors (12) for carrying out a carbonation reaction, wherein the tubular reactors (12) are operable under a pressure of > 1 bar and wherein the tubular reactors (12) have at least one media inlet (18) through which a reaction mixture can be introduced into the tubular reactors (12) which are under a pressure of > 1 bar, wherein the reactor system (10) has at least one inlet (28) for introducing carbon dioxide into the tubular reactors (12); and wherein the reactor system (12) has a separation unit (34) for substance and / or phase separation of a reaction mixture flowing out of the tubular reactor (12).

2. Reactor system (10) according to claim 1, characterized in that the reactor system has tubular reactors (12) with different diameters, or that at least one tubular reactor (12) has a diameter of varying size.

3. Reactor system (10) according to claim 1 or 2, characterized in that the reactor system (10) downstream of the separation unit (34) can be operated under a pressure of > 1 bar.

4. Reactor system (10) according to one of claims 1 to 3, characterized in that a comminution unit (20) is provided, by means of which a solid starting product can be comminuted before being introduced into the tubular reactor (12).

5. Reactor system (10) according to one of claims 1 to 4, characterized in that the reactor system (10) comprises at least one processing unit (56) for mechanically processing solids present in the reaction stream, wherein the processing unit is arranged between two tubular reactors (12).

6. Reactor system (10) according to one of claims 1 to 5, characterized in that at least one sensor (16) is provided for detecting gaseous components in at least one tubular reactor (12).

7. Reactor system (10) according to one of claims 1 to 6, characterized in that heat generated at the tubular reactor (12) can be reused at another location in the reactor system (12).

8. Reactor system according to one of claims 1 to 7, characterized in that at least one tubular reactor (12) is equipped with a temperature control unit, wherein the temperature control unit has a fluid guide for guiding fluid temperature control medium, which runs on the outer circumference of the at least one tubular reactor (12).

9. Reactor system (10) according to one of claims 1 to 8, characterized in that upstream of the separation unit (34) at least one of an expansion unit for at least partially expanding the process stream and a gas separator (40) is provided.

10. Reactor system (10) according to one of claims 1 to 9, characterized in that the plurality of tubular reactors (12) are connected in series.

11. Reactor system (10) according to one of claims 1 to 10, characterized in that the plurality of tubular reactors (12) are connected in parallel.

12. Reactor system (10) according to one of claims 1 to 11, characterized in that the tubular reactors (12) are part of a circulation system.

13. Reactor system according to one of claims 1 to 12, characterized in that at least one inlet (28) for introducing carbon dioxide into the tubular reactors (12) is designed as an exchangeable nozzle.

14. A continuous carbonation process, comprising the process steps: a) providing a carbonation reactant, wherein the carbonation reactant is suitable for reacting with carbon dioxide; b) providing carbon dioxide; and c) reacting the carbonation reactant with carbon dioxide to chemically bind the carbon dioxide, wherein process step c) is carried out in a reaction system (10) according to one of claims 1 to 13.

15. The method according to claim 14, characterized in that reaction product obtained after process step c) is removed from the reaction system (10) by means of a separation unit (34), wherein particles up to a defined size range are reused in process step c) as a component of the reaction stream downstream of the separation unit (34).

16. Use of a reactor system (10) according to one of claims 1 to 13 or of a method according to one of claims 14 or 15 for producing paints, cement or cement substitutes, fillers, in particular for paper products, polymer products or for concrete, or products for road construction.

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