FR3144528A1 - Carbonation reactor, device and process - Google Patents

Abstract

Material carbonation reactor (10), characterized in that it comprises: A set of compartments of at least 3, stacked vertically and each separated from one another by an operable hatch, the main compartment (112) being positioned between two compartments. One or more upper compartments (111) located above the main compartment (112); One or more lower compartments (113), located below the main compartment (112); an operable hatch (114) between the ambient air and the upper compartments (111), serving as an entrance for the materials to be carbonated; an operable hatch (115) between the upper compartments (111) and the main compartment (112); an operable hatch (116) between the main compartment (112) and the lower compartments (113); an operable hatch (117) between the lower compartments (113) and the ambient air, acting as an outlet for the carbonated materials; an inlet for CO2 for the main compartment, with a supply valve (118);A CO2 outlet for the main compartment, with an exhaust valve (119);An exhaust vent (120) in the upper compartments (111) located above the central compartment (112), with a pilot-operated and waterproof opening device. A gaseous CO2 suction device (121) connecting the lower compartments (113) to the upper compartments (111), and comprising a transfer device (122);

Description

Carbonation reactor, device and process TECHNICAL FIELD OF THE INVENTION

The present invention relates to a reactor, a device and a process for carbonating materials using supercritical CO2. It applies in particular to concrete recycling platforms, to units manufacturing new concrete from recycled aggregates and to asphalt production plants.

STATE OF THE ART

The carbonation of concrete occurs naturally in contact with the concrete and the atmosphere (with an atmospheric CO2 content of around 400 ppm). This phenomenon is for example explained in the scientific article “The sponge effect and carbon emission mitigation potentials of the global cement cycle” from 2020, Nature, by Z.Cao et al. For concrete, the reaction involved can be represented by:
Ca(OH) ₂ + CO ₂ -> CaCO ₃ + H2O (Equation 1)

In this equation, calcium hydroxide reacts with CO2 to produce calcium carbonate and water. The walls of concrete constructions are thus affected by this phenomenon, with a certain depth over which the carbonation reaction occurs. The carbonation of concrete structures is generally not complete. The carbonation of concrete structures reduces the pH of the environment and can induce corrosion in the metal reinforcements of the latter. This natural phenomenon can be channeled and accelerated, within the framework of what is called accelerated carbonation of materials. Among the objectives of this practice, we will note on the one hand an ability to trap and store CO2, on the other hand an improvement in the performance of the materials thus treated and finally, the capacity to better valorize certain materials, following carbonation.

It should be noted that carbonation can be carried out on many materials other than concrete as long as a carbonatable base, such as for example calcium hydroxide Ca(OH)2, or even magnesium hydroxide Mg(OH)2 ) is present in the material.

We recall several important definitions regarding carbonation. On the one hand, the carbon yield (in %) indicates the quantity of CO2 actually trapped in relation to the quantity of CO2 made available. On the other hand, the trapping rate (or uptake, in kg of CO2 per kg of material) designates the quantity of CO2 trapped per quantity of materials introduced. Finally, the capacity of a carbonation unit (in tonnes of material per hour) designates the quantity per hour of material that can be carbonated.

The carbonation of concrete waste consists of reacting certain chemical species present on this concrete waste with CO2 to obtain new physicochemical properties of the materials and trap CO2. Concrete waste refers to different concrete products that are recovered and then crushed, and where appropriate, separated into different particle size fractions, these concrete products being able to be the origin of the bottoms of concrete production unit tanks, waste from deconstruction sites, platform waste, etc. We then speak of recycled concrete aggregates for fractions of high particle size, typically with a particle size greater than 4 mm, and of recycled concrete sand for fractions of a particle size less than 4 mm, with particular attention to fines, a fraction which may correspond to a particle size less than 1 mm. There is scientific work forming a fairly dense and old corpus on the study of the carbonation phenomenon for concrete (including concrete waste), such as for example the scientific article “Carbonation of concrete and its prediction”, Cement and Concrete Research Volume 17, Issue 3, May 1987, Pages 489-504, by Ho et al.

As a more recent example, patent FR3113465 - A1 (filed in January 2021) describes a process for carbonating a fine fraction resulting from a previous process for dissociating deconstruction concrete. This process, which targets the fine fraction of concrete waste, is based on gaseous CO2 and uses a vibration device. Note that the proposed operating parameters (temperature, pressure, humidity, CO2 content, particle size) are well known in the literature, as mentioned in the article “Effect of the accelerated carbonation treatment on the recycled sand physicochemical characteristics through the rolling carbonation process” by Dos Reis et al, 2020. These parameters being known, the solutions can stand out by the constructive arrangements of the reactors.

Patent WO2021/228979 describes a carbonation process with reactors filled with aggregates which are then carbonated, and operating “in batch”, that is to say in batches treated one after the other. The emphasis is placed in particular on controlling the reaction and measuring performance in the context of using a “gas comprising CO2” and preferably with a “gas introduced into the container… (comprising) 95 to 100% of CO2 »

The use of a gas rich in CO2 within these inventions limits the performance of the processes in terms of 1) CO2 capture rate, 2) carbonation duration (of the order of an hour) and consequently , the unit flow that can be processed by a given installation. Finally, in certain cases, the carbon yield may be low, due to a lack of measurement of CO2 losses linked to the process.

Other inventions and scientific programs aim to achieve continuous carbonation (from the point of view of the CO2 used). This is the case of the developments presented as part of the Fastcarb program in France, having given rise to research demonstrators, the results of which were published in June 2021. In these inventions, fumes from cement plants, rich in CO2 ( typically a composition between 20 and 25% on a molar basis) are introduced into the carbonation reactor. Although the production capacity can be significant, the main disadvantage of this type of solution is the low carbon efficiency, because a lot of the CO2 introduced comes out without having reacted. Furthermore, carbonation with a gas comprising 20 to 25% by molar base of CO2 may require a very slow carbonation duration, of the order of several hours or even several days to be considered sufficient, i.e. carbonate a large part of carbonatable species.

1. Un taux de piégeage limité ;
2. Un rendement carbone limité ;
3. Une capacité limitée ;
4. Une difficulté à mesurer de manière précise la quantité de CO2 piégée dans le dispositif, notamment via la mesure uniquement indirecte du CO2 piégée et l’absence de mesure du CO2 perdu.

Thus, there are technical solutions for carbonated concrete waste using a gas rich in CO2, but these solutions may be limited by all or part of the following aspects:

1. A limited trapping rate;
2. Limited carbon yield;
3. Limited capacity;
4. A difficulty in precisely measuring the quantity of CO2 trapped in the device, in particular via the only indirect measurement of the CO2 trapped and the absence of measurement of the CO2 lost.

Remember that the critical point of CO2 is defined by a temperature of 31°C and a pressure of 73.7 bar, and that under pressure and temperature conditions higher than critical conditions, CO2 is in the supercritical state, a state combining fluid properties of liquid and gas types, such as for example high density and excellent diffusivity.

Other work aims to achieve carbonation using CO2 in the supercritical state. Patent US5518540 of May 1996 presents the case of an invention aimed at treating cement to reinforce its properties, particularly in the context of incorporating other materials. The process is nevertheless not very detailed and concerns the reinforcement of cement. Remember that concrete is generally composed of cement, aggregate, water and air.

Patent US6264736B1 published in 2001 presents an invention for rapidly carbonate large cement structures, in cement format hardened in a mold, via the use of supercritical CO2. The process presented does not detail the elements of the device beyond the mention of a waterproof compartment. This system may have the following limitations: on the one hand, without recovery, the CO2 that does not react is lost, which reduces the carbon yield. On the other hand, in the absence of precision, the way of incorporating CO2 and materials constitutes an important issue in terms of capacity (in t/h) and technical feasibility. The device does not present the carbonation of concrete waste, and therefore does not make it possible to better exploit these material resources. The scientific article “Experimental measurement of portlandite carbonation kinetics with supercritical CO2” by Regnault et al., 2014, describes carbonation tests using supercritical CO2. These tests are carried out on laboratory reactors, but do not present the details of an industrial process, nor the means to precisely measure the quantity of CO2 trapped continuously in the process.

Thus, there are scientific approaches to carbonate cement elements using CO2 in the supercritical state, but no invention presenting how to resolve the limitations mentioned previously, in particular for concrete waste or all carbonatable materials. .

OBJECT OF THE INVENTION

1. Un ensemble de compartiments au minimum de 3, empilés verticalement et séparés chacun l’un de l’autre par une trappe actionnable, le compartiment principal (112) étant positionné entre deux compartiments.
2. Un ou plusieurs compartiments supérieurs (111), situés au-dessus du compartiment principal (112) ;
3. Un ou plusieurs compartiments inférieurs (113), situés au-dessous du compartiment principal (112) ;
4. une trappe actionnable (114) entre l’air ambiant et les compartiments supérieurs (111), faisant office d’entrée des matériaux à carbonater ;
5. une trappe actionnable (115) entre les compartiments supérieurs (111) et le compartiment principal (112) ;
6. une trappe actionnable (116) entre le compartiment principal (112) et les compartiment inférieurs (113) ;
7. une trappe actionnable (117) entre les compartiments inférieurs (113) et l’air ambiant, faisant office de sortie des matériaux carbonatés ;
8. Une entrée pour le CO2 supercritique pour le compartiment principal, avec une vanne d’alimentation (118) ;
9. Une sortie pour le CO2 supercritique pour le compartiment principal, avec une vanne d’extraction (119) ;
10. Un évent d’évacuation (120) dans les compartiments supérieurs (111) situés au-dessus du compartiment central (112), avec un dispositif d’ouverture piloté et étanche ;
11. Un dispositif d’aspiration du CO2 gazeux (121) connectant les compartiments inférieurs (113) aux compartiments supérieurs (111), et comportant un dispositif de transfert (122);

The present invention aims to remedy all or part of these drawbacks. To this end, according to a first aspect, the present invention aims at a material carbonation reactor (110), which comprises:

1. A set of compartments of at least 3, stacked vertically and each separated from one another by an operable hatch, the main compartment (112) being positioned between two compartments.
2. One or more upper compartments (111), located above the main compartment (112);
3. One or more lower compartments (113), located below the main compartment (112);
4. an operable hatch (114) between the ambient air and the upper compartments (111), serving as an entry point for the materials to be carbonated;
5. an operable hatch (115) between the upper compartments (111) and the main compartment (112);
6. an operable hatch (116) between the main compartment (112) and the lower compartments (113);
7. an operable hatch (117) between the lower compartments (113) and the ambient air, serving as an outlet for carbonated materials;
8. A supercritical CO2 inlet for the main compartment, with a supply valve (118);
9. A supercritical CO2 outlet for the main compartment, with an extraction valve (119);
10. An exhaust vent (120) in the upper compartments (111) located above the central compartment (112), with a pilot-operated and waterproof opening device;
11. A CO2 gas suction device (121) connecting the lower compartments (113) to the upper compartments (111), and comprising a transfer device (122);

In some embodiments, the materials introduced at the top of the reactor will descend in stages through the compartments, until they reach the main compartment where a quantity of CO2 will be injected, in supercritical form, and where the carbonation reaction will mainly take place. The upper compartments thus play the role of an airlock to avoid the loss of CO2 by improving sealing, and maximizing carbon efficiency.

In embodiments, each compartment is waterproof. Fluids (CO2 gas or supercritical CO2) can only enter or leave the compartments when a valve, a hatch or via an extraction device is opened. This makes it possible on the one hand to avoid the loss of CO2 and thus to maximize carbon yield, and on the other hand, to know precisely the quantity of CO2 trapped.

In embodiments, the carbonate materials in the main compartment gradually descend into the lower compartments, until the outlet. This sequencing ensures good sealing and maximum carbonation.

In embodiments, the useful volume of a certain compartment can be variable, via the presence of a piston in addition to the presence of an operable hatch. This allows better control of the pressure in the compartments

In embodiments, several reactors are connected in parallel on the main circuit. This increases the throughput of processed materials.

In embodiments, the central compartment has a larger volume than the upper compartment. This makes it easier to manage the flow of materials in the reactor.

In embodiments, the gaseous CO2 from the lower compartments is injected into the upper compartments via the extraction device. This allows the following advantages: firstly, to avoid the loss of CO2 when opening the lower compartment into the open air and therefore to improve carbon efficiency; secondly, to partly expel the air from the upper compartments; thirdly, to start the carbonation reaction in the upper compartments; fourthly, to contribute to the precise measurement of the quantity trapped in the materials.

In embodiments, the reactor comprises several lower compartments, equipped with gas extraction devices and allowing the reinjection of gas (mainly CO2) into the upper behaviors. This further improves carbon efficiency.

In embodiments, the valves at the inlet and outlet of the reactor are very close to the reactor. This makes it possible to better dose the quantity of CO2 to be carbonated in the main compartment and to better control the final pressure at the end of carbonation, and thus to better control the thermodynamic cycle.

In embodiments, the quantity of materials introduced into the upper compartment is precisely metered relative to the quantity of CO2 injected into the main compartment, to maximize carbonation and pressure management in the reactor.

In some embodiments, this dosage is done by filling the entire upper compartment, the volume of which is known, with a scraper-type material recovery device, the materials being to be reincorporated into the next loading. By knowing the density of bulk materials, this makes it possible to know approximately the mass of materials introduced.

In embodiments, the operable hatch between the upper compartment and the main compartment comprises fixed or mobile internal devices making it possible to create a slight mixture within the materials. This improves the carbonation reaction.

In embodiments, the hatches operable between compartments can have a progressive and controlled opening mode, i.e. the opening speed can be regulated.

In embodiments, two actions make it possible to reduce the pressure in the main compartment to a pressure lower than the critical pressure of 73.7 bar: on the one hand the carbonation reaction, via the consumption of CO2 passing from the state gaseous in the solid state, and on the other hand, the opening of the lower hatch making it possible to pool the volumes of the main compartment and the directly lower compartment. This makes it possible to transform supercritical CO2 into gaseous CO2 by reducing the pressure, and thus to more easily separate the flow of CO2 from the flow of materials.

In embodiments, the CO2 introduced into the reactor is in the liquid state, at a pressure between 75 bar and 130 bar and at a temperature between 37°C and 100°C, and the CO2 emerging from the reactor is in the gaseous state, at a pressure between 20 bar and 70 bar and a temperature between 20°C and 80°C. This choice makes it possible to optimize the carbonation reaction and the separation of materials and non-reactive CO2 in the reactor.

In embodiments, the reactor does not include CO2 extraction valves at the main compartment and the device does not include a recirculation circuit with separator, condenser and reintroduction into the storage tank. Only gaseous CO2 is extracted from the lower compartments and recycled to the upper compartments. This makes it possible to reduce costs and increase energy performance when the quantities of CO2 and materials are precisely dosed.

In embodiments, the vent present in the upper compartments is located on a high point of the compartment. This makes it possible to evacuate the air which could accumulate in the reactor and in the compartments, the CO2 being heavier than the air, it will tend to be located high up in the compartments.

In embodiments, the vent device includes a device for measuring the quantity of residual CO2 discharged to the vent;

In embodiments, the reactor comprises a device for measuring the quantity of residual CO2 in the lower compartment, after extraction and before opening the operable hatch communicating with the ambient air;

In embodiments, the materials to be carbonated are crushed recycled concrete waste having a humidity level greater than 5%, and with a particle size less than 80 mm;

1. Une ligne d’alimentation en CO2 liquide débouchant sur un réservoir de CO2 liquide sous pression et comportant :
   1. un système de dosage en débit et
   2. un système de mesure de quantité et ;
2. Un réservoir de CO2 liquide sous pression ;
3. Une pompe de CO2 liquide sous pression, connecté au réservoir et à l’échangeur thermique de type réchauffeur ;
4. Un échangeur thermique de type gaz/liquide, permettant d’une part un chauffage du CO2 gazeux restant en sortie de réacteur, et d’autre part le chauffage complémentaire du CO2 liquide
5. Un échangeur thermique de type réchauffeur de CO2 liquide sous pression, connecté au réacteur et à la pompe. Cet échangeur est également dit échangeur trans-critique ;
6. Un réacteur de carbonatation tel que décrit selon le premier aspect de l’invention ;
7. Un séparateur additionnel gaz / solide;
8. Un échangeur thermique de type condenseur de CO2 gazeux ;
9. Un ensemble de tuyauteries connectant les composants précédemment cités ;

According to a second aspect, the present invention aims at a device for carbonating materials, which comprises:

1. A liquid CO2 supply line opening onto a pressurized liquid CO2 tank and comprising:
   1. a flow dosing system and
   2. a quantity measurement system and;
2. A pressurized liquid CO2 tank;
3. A pressurized liquid CO2 pump, connected to the tank and the heater type heat exchanger;
4. A gas/liquid type heat exchanger, allowing on the one hand heating of the gaseous CO2 remaining at the reactor outlet, and on the other hand the additional heating of the liquid CO2
5. A pressurized liquid CO2 heater type heat exchanger, connected to the reactor and the pump. This exchanger is also called a trans-critical exchanger;
6. A carbonation reactor as described according to the first aspect of the invention;
7. An additional gas/solid separator;
8. A gaseous CO2 condenser type heat exchanger;
9. A set of pipes connecting the previously mentioned components;

The device can be considered as a thermodynamic machine carrying out compression, heat exchange, expansion and heat exchange work, and with a fluid being CO2, in three different states (gaseous, liquid, supercritical). We can therefore designate a thermodynamic cycle, the entire circuit in the device allowing these transformations of CO2.

In embodiments, there is no gas/liquid type heat exchanger. This makes it possible to reduce costs and pressure drops when the quantity of gaseous CO2 recovered is low.

In embodiments, liquid CO2 from the tank is pumped to a pressure above the critical pressure and then reheated to a temperature above the critical temperature. This allows supercritical phase carbonation to be achieved in the main compartment, improving the penetration depth, carbonation rate and reducing the duration of the carbonation reaction.

In some embodiments, the flow rate entering the reactor is greater than the flow rate leaving the reactor, resulting in a higher thermal power for the pressurized liquid CO2 heating exchanger than for the liquid CO2 cooling and liquefaction exchanger.

In embodiments, several reactors are arranged in parallel on the CO2 circuit. This makes it possible to significantly increase the capacity of the unit and operate almost continuously.

In embodiments, the gas/solid separator located after the reactor is of the cyclone type. It makes it possible to recover any fine carbonates, increasing material recovery and reducing wear on CO2 circuit components. It has a waterproof, operable hatch to evacuate materials, while limiting CO2 losses.

In embodiments, the gas/solid separator located after the reactor is equipped with a set of compartments at the bottom of the equipment and extractors, acting as airlocks and making it possible to limit the loss of CO2 in the flow of materials . The solids captured in the separator are then only evacuated during the maintenance phase.

In embodiments, the entire invention can be arranged on a mobile assembly, and works by campaign. From several hours to several weeks.

In embodiments, the device is supplied with liquefied CO2 under pressure via the CO2 supply.

In embodiments, the CO2 tank is at a pressure of 20 bar and a temperature of -18°C.

In other embodiments, the CO2 tank is at a pressure of 50 bar and a temperature of 8°C.

In embodiments, the CO2 is available in liquid form at a given pressure and temperature, and a compression device then a heat exchanger makes it possible to make CO2 available at a higher pressure and temperature at the level of the line. 'food.

In embodiments, the quantity of CO2 injected into the device via the CO2 supply line is precisely dosed using the flow metering system and precisely measured using the quantity measuring system. Combined with the very low CO2 loss rate, this allows for continuous measurement of the quantity of CO2 trapped in the materials.

In embodiments, the flow metering system is an actuable valve.

In embodiments, the quantity measurement system is a flow meter.

In embodiments, there is instrumentation making it possible to measure the concentration of CO2 present at the level of the lower compartment and at the level of the upper compartment. This makes it possible to precisely quantify the CO2 losses and therefore the carbon yield, when the reactor's operable hatches opening onto the ambient air are opened.

In embodiments, the lower reactor compartment CO2 extraction device extracts CO2 to the main circuit after the reactor instead of sending it to the upper reactor compartments. This can help reduce costs in the case of multiple reactors.

In embodiments, the liquid CO2 tank is physically positioned above the pump so as to avoid cavitation thereof.

In embodiments, the device (20) comprises a set of several reactors (210) connected in parallel and each operating with a time shift equivalent to the carbonation duration divided by the number of reactors (210);

1. Un dispositif de carbonatation de matériaux, selon le second aspect de l’invention
2. Un circuit pompe à chaleur intégré, comprenant à minima:
3. Un compresseur ;
4. Un dispositif de détente de gaz ;
5. Un fluide de travail ;
6. Un ensemble de tuyauteries connectant le compresseur, la vanne de détente, l’échangeur de type réchauffeur de CO2 et l’échangeur de type condenseur de CO2 gazeux, caractérisé selon que :

According to a third aspect, the present invention aims at a device for carbonating materials, which comprises:

1. A device for carbonating materials, according to the second aspect of the invention
2. An integrated heat pump circuit, including at least:
3. A compressor;
4. A gas expansion device;
5. A working fluid;
6. A set of pipes connecting the compressor, the expansion valve, the CO2 heater type exchanger and the gaseous CO2 condenser type exchanger, characterized in that:

The CO2 heater type exchanger of the material carbonation device heats the CO2 stream and condensing and/or cooling the working fluid. It is located upstream of the gas expansion device;

The CO2 condenser type exchanger of the material carbonation device cools and/or liquefies the CO2 flow by heating and/or evaporating the working fluid. It is located upstream of the compressor;

The aims, advantages and particular characteristics of the device which is the subject of the second aspect of the present invention being similar to those of the device which is the subject of the first aspect which is the subject of the present invention, they are not recalled here.

In addition to these advantages, this third aspect makes it possible to optimize energy consumption and the autonomy of the process.

In embodiments, the CO2 condenser exchanger of the material carbonation device is also the evaporator of the heat pump circuit and the CO2 heater exchanger is also the condenser of the heat pump circuit.

In embodiments, the working fluid of the heat pump circuit is also CO2 under pressure.

In other embodiments, the working fluid is an HFO type refrigerant or a natural fluid (hydrocarbon type). This helps optimize performance.

In embodiments, the heat exchangers common to the CO2 and heat pump circuits comprise several sub-parts, some of which can be dedicated to temperature changes and others to changes of state.

In embodiments, there are complementary exchangers for heating the liquid CO2 (respectively cooling or liquefying the gaseous CO2) with an external hot (respectively cold) source. This allows more flexibility depending on operating conditions.

In embodiments, the compressor of the heat pump circuit is of the multi-stage type.

In embodiments, the heat pump circuit includes additional improvements well known from the literature, such as an intermediate exchanger, several pressure levels, several nested circuits with different working fluids. This improves the performance of the heat pump circuit.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages, aims and particular characteristics of the invention will emerge from the following non-limiting description of at least one particular embodiment of the device and the method which are the subject of the present invention, with reference to the appended drawings, in which:

there represents, schematically, a first particular embodiment of the carbonation reactor, object of the present invention,

there represents, schematically, a second particular embodiment of the device which is the subject of the present invention,

there represents, schematically, a third particular embodiment of the device which is the subject of the present invention,

there represents, schematically, a particular temperature-pressure diagram of the thermodynamic cycle implemented by the device which is the subject of the present invention,

there represents, schematically and in the form of a flowchart, a particular succession of steps of the process which is the subject of the present invention.

The present description is given on a non-limiting basis, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner. Note now that the figures are not to scale.

1. Un ensemble de compartiments au minimum de 3, empilés verticalement et séparés chacun l’un de l’autre par une trappe actionnable, le compartiment principal (112) étant positionné entre deux compartiments.
2. Un ou plusieurs compartiments supérieurs (111) situés au-dessus du compartiment principal (112) ;
3. Un ou plusieurs compartiments inférieurs (113) , situés en dessous du compartiment principal (112) ;
4. Une trappe actionnable (114) entre l’air ambiant et les compartiments supérieurs (111), faisant office d’entrée des matériaux à carbonater ;
5. Une trappe actionnable (115) entre les compartiments supérieurs (111) et le compartiment principal (112) ;
6. Une trappe actionnable (116) entre le compartiment principal (112) et les compartiment inférieurs (113) ;
7. Une trappe actionnable (117) entre les compartiments inférieurs (113) et l’air ambiant, faisant office de sortie des matériaux carbonatés ;
8. Une entrée pour le CO2 supercritique pour le compartiment principal, avec une vanne d’alimentation (118) ;
9. Une sortie pour le CO2 supercritique pour le compartiment principal, avec une vanne d’évacuation (119) ;
10. Un évent d’évacuation (120) dans les compartiments supérieurs (111) situés au-dessus du compartiment central (112), avec un dispositif d’ouverture piloté et étanche ;
11. Un dispositif d’aspiration du CO2 gazeux (121) connectant les compartiments inférieurs (113) aux compartiments supérieurs (111), et comportant un dispositif de transfert (122) ;

We observe, on the , a schematic view of one embodiment of the device which is the subject of the present invention. This material carbonation reactor (10) comprises:

1. A set of compartments of at least 3, stacked vertically and each separated from one another by an operable hatch, the main compartment (112) being positioned between two compartments.
2. One or more upper compartments (111) located above the main compartment (112);
3. One or more lower compartments (113), located below the main compartment (112);
4. An operable hatch (114) between the ambient air and the upper compartments (111), serving as an entry point for the materials to be carbonated;
5. An operable hatch (115) between the upper compartments (111) and the main compartment (112);
6. An operable hatch (116) between the main compartment (112) and the lower compartments (113);
7. An operable hatch (117) between the lower compartments (113) and the ambient air, serving as an outlet for carbonated materials;
8. A supercritical CO2 inlet for the main compartment, with a supply valve (118);
9. A supercritical CO2 outlet for the main compartment, with an exhaust valve (119);
10. An exhaust vent (120) in the upper compartments (111) located above the central compartment (112), with a pilot-operated and waterproof opening device;
11. A CO2 gas suction device (121) connecting the lower compartments (113) to the upper compartments (111), and comprising a transfer device (122);

The reactor (10) can for example be installed within a carbonation device presented in .

The supercritical CO2 flow enters the main compartment (112) of the reactor (110), when the valve (118) is open. The reactor (110) has for example 3 compartments, including a main compartment (112). The operable hatches (115) and (116) are closed when the valve (118) is opened.

The materials to be carbonated are for example crushed concrete waste and are introduced at the level of the hatch (114) into the upper compartment (111).

The operable hatches (114), (115), (116) and (117) are for example gate valves.

The upper compartment (111) has an inverted cone shape to facilitate loading of materials.

The reactor (10) will treat a flow of material with a flow of CO2. From the point of view of the CO2 flow, The supercritical CO2 flow enters the main compartment of the reactor (112), when the valve (118) is opened. Inside the main compartment (112), the CO2 meets the materials to be carbonated. It also induces a drop in pressure in the main compartment (112). When this reaction is complete, the operable hatch (116) between the main compartment (112) and the lower compartments (113) opens and the materials fall into the lower compartment (113). The two volumes are therefore in common and this opening induces an additional drop in pressure. The CO2 is then gaseous. The hatch (113) closes and the outlet valve (119) opens. The carbonation reaction is rapid.

From a material flow point of view, a metered quantity of materials is placed in the upper compartment (111) of the reactor (110), via an operable hatch (114) which opens. This compartment (111) acts as an airlock. The air initially present at atmospheric pressure can be expelled using a device (120) (vacuum pump or vent type). The upper compartment (111) can then be progressively supplied with CO2 under pressure, coming from a lower compartment (113). Via the opening of the lower hatch (115), the materials fall into the main compartment (112). The hatch (115) closes and the CO2 supply valve (118) opens. The carbonation reaction occurs. Once the reaction is complete, the lower operable hatch (116) moves the materials into the lower compartment (113) and then closes.

A CO2 gas extraction device (121) further reduces the pressure in the lower compartment (113) to a level close to atmospheric pressure. The gaseous CO2 extracted by the extraction device (121) can reach the upper compartment (111). The extraction device (121) comprises for example a suction system (122), of the volumetric compressor type.

The vent device (120) can advantageously be arranged in height to preferentially expel air rather than CO2. The vent device (120) may also be waterproof, with controlled opening. The vent device (120) may include supplying other accessories such as a gas tank, with a device for measuring the quantity of CO2 released.

1. Une ligne d’alimentation en CO2 liquide comportant un système de dosage en débit (201) et un système de mesure de quantité (202) et débouchant sur un réservoir de CO2 liquide sous pression (203) ;
2. Un réservoir de CO2 liquide sous pression (203) ;
3. Une pompe de CO2 liquide sous pression, (204) connecté au réservoir de CO2 liquide sous pression (203) et à un échangeur thermique (220) de type gaz/liquide.
4. Un échangeur thermique (220) de type gaz/liquide, permettant d’une part un chauffage du CO2 gazeux restant en sortie de réacteur (210), et d’autre part le chauffage complémentaire du CO2 liquide
5. Un échangeur thermique de type réchauffeur de CO2 liquide sous pression (205), connecté à l’échangeur (220) et au réacteur (210). Cet échangeur est également dit échangeur trans-critique ;
6. Un réacteur (210) tel que décrit en et comportant :
   1. Une entrée pour le CO2 supercritique pour le compartiment principal, avec une vanne d’alimentation (218) ;
   2. Une sortie pour le CO2 supercritique pour le compartiment principal, avec une vanne d’évacuation (219) ;
7. Un séparateur additionnel gaz / solide (206), avec une trappe actionnable étanche (207) ;
8. Un échangeur thermique de type condenseur de CO2 gazeux (208) ;
9. Un ensemble de tuyauteries connectant les composants, venant compléter le circuit CO2 (209) ;

We observe, on the , a schematic view of one embodiment of the device which is the subject of the present invention. This device (20) for carbonating materials comprises:

1. A liquid CO2 supply line comprising a flow rate dosing system (201) and a quantity measuring system (202) and opening onto a pressurized liquid CO2 tank (203);
2. A pressurized liquid CO2 tank (203);
3. A pressurized liquid CO2 pump (204) connected to the pressurized liquid CO2 tank (203) and to a gas/liquid type heat exchanger (220).
4. A gas/liquid type heat exchanger (220), allowing on the one hand heating of the gaseous CO2 remaining at the reactor outlet (210), and on the other hand the complementary heating of the liquid CO2
5. A pressurized liquid CO2 heater type heat exchanger (205), connected to the exchanger (220) and the reactor (210). This exchanger is also called a trans-critical exchanger;
6. A reactor (210) as described in and comprising:
   1. A supercritical CO2 inlet for the main compartment, with a supply valve (218);
   2. A supercritical CO2 outlet for the main compartment, with an exhaust valve (219);
7. An additional gas/solid separator (206), with a watertight operable hatch (207);
8. A gaseous CO2 condenser type heat exchanger (208);
9. A set of pipes connecting the components, completing the CO2 circuit (209);

The device (20) can for example be installed within a concrete production plant, or on a concrete waste recycling platform.

The tank (203) is for example a cylindrical pressure tank. Liquid CO2 is stored, for example, at a pressure of around 20 to 50 bar.

The pump (204) is for example a centrifugal pump, or a membrane pump, making it possible to pressurize the liquid CO2 to a pressure greater than 74 bar.

The exchanger (205) is for example a tube and shell exchanger or a brazed plate exchanger, making it possible to heat the CO2 above the critical temperature. It is fed by a hot spring, not shown.

The invention (20) may include several reactors (210) in parallel

The solid/gas separator (206) is for example of the cyclone type, with a lower hatch (207) allowing the seal to be completed. The solid/gas separator (206) may also include an airlock and/or additional compartments to improve the sealing of the device and the flow of solid materials out of the circuit, with minimal loss of CO2.

The solid/gas separator can also be a cartridge-type filter or a set of filters arranged in series and/or parallel in order to filter the particles which would be carried away by the gas flow out of the reactor.

From the point of view of the thermodynamic cycle in play, the CO2 coming from the tank (203 and pressurized by the pump (204) is then heated to a temperature higher than the critical temperature in the trans-critical heater (205) and passes to the supercritical state. The flow of supercritical CO2 then enters the reactor (210) when the valve (218) is opened. Inside the reactor (210), the CO2 meets the materials to be carbonated. ) opens, the remaining CO2, not trapped, can be routed to the gas/solid separator (206). The exchanger (220) can allow heat recovery from the flow leaving the reactor (210) and the separator (). 206). The gas/liquid type exchanger (220) can recover heat to preheat the liquid before the exchanger (205). The gaseous CO2 is then directed to the condenser (208) where it is cooled. then liquefied. The liquid CO2 then joins the tank (203), to start the cycle again. A liquid CO2 supply line comprising a flow metering system (201) and a quantity measuring system (202) supplies the tank. (203) to top up the liquid CO2 level.

The exchanger (208) is for example a tube and shell exchanger or a brazed plate exchanger, making it possible to cool and condense the gaseous CO2. It is powered by a cold source, not shown.

The vent device (120) of a reactor can be connected to a gas tank common to other devices from other reactors.

We observe, on the , a schematic view of one embodiment of the device which is the subject of the present invention. This device (30) for carbonating materials comprises:

A carbonation device (301) as described in and comprising:

A carbonation reactor (310)

An exchanger (305) for heating the liquid CO2 entering the reactor (310)

An exchanger (308) for cooling and/or liquefying the gaseous CO2 leaving the reactor (310)

1. Un compresseur (303)
2. Un dispositif de détente (304)
3. Un ensemble de tuyauterie et d’accessoires (305) transportant un fluide de travail entre les différents composants du circuit

A heat pump circuit (302), comprising at least:

1. A compressor (303)
2. A relaxation device (304)
3. A set of piping and accessories (305) transporting a working fluid between the different components of the circuit

The heat pump circuit allows heat recovery on the exchanger (308) and heat evacuation on the exchanger (305).

The compressor (103) can for example be a positive displacement, scroll, screw or piston compressor. The compressor can also be of the centrifugal type. The compressor (103) can compress the low pressure gaseous working fluid into the high pressure working fluid. The compressor (103) can be composed of several compression stages, where appropriate with intermediate pressure levels.

The exchanger (305) for heating the liquid CO2 within the device (301) cools and condenses the working fluid of the heat pump circuit (302). For the working fluid, it can be a condenser type exchanger. At the outlet of the exchanger (305), the working fluid is in the state of liquid under pressure.

The expansion device (104) may be an expansion valve, allowing expansion of the working fluid in the high-pressure liquid state into a low-pressure two-phase (gas/liquid) working fluid, at a lower temperature.

The exchanger (308) to cool and/or condense the liquid CO2 within the device (301) heats and/or evaporates working fluid from the heat pump circuit (302). For the working fluid, it can be an evaporator type exchanger. At the outlet of the exchanger (305), the working fluid is in the state of low pressure gas.

The piping and accessories assembly (305) may include intermediate recovery exchangers, several pressure levels, and/or ejectors to improve the performance of the heat pump circuit.

The working fluid within the heat pump circuit can be CO2, or a propane, butane, pentane type fluid or a mixture. The working fluid can also be ammonia, or an HFO (Hydro-Fluoro-Olefin) or HFE (Hydrofluoroether) type refrigerant.

We observe in , a pressure – temperature diagram of CO2 on which is superimposed the thermodynamic cycle of the device (20) or (30), with regard to CO2, according to a particular mode of implementation. The ordinate is in absolute bar and the abscissa in degrees Celsius. Note that the diagram is not to scale.

In this particular mode of implementation, the liquid CO2 is at a pressure of 20 bar and -18°C (represented by point 1). It is then compressed up to 80 bar (point 2). The temperature increases slightly. The CO2 is then heated to a temperature of 41°C (point 3) in the supercritical region. Then, within the main reactor compartment, the pressure drops to around 20 bar in connection with the carbonation reaction and the modification of the volume. The non-trapped CO2 becomes gaseous at the end of these actions and the temperature is slightly reduced to 33°C (point 4). The non-trapped CO2 is then cooled and then liquefied in the condenser to return to initial conditions (point 1).

1. une étape (510) de carbonatation des matériaux, comportant :
   1. une étape d’entrée et de dosage des matériaux carbonatés (511) ;
   2. une étape d’entrée des matériaux dans les compartiments supérieurs du réacteur (512) ;
   3. une étape d’entrée dans le compartiment principal (513) ;
   4. une étape de réaction de carbonatation principale (514), induisant une baisse de pression dans le compartiment principal ;
   5. une étape d’entrée dans le compartiment inférieur (515), liée à l’ouverture d’une trappe actionnable, en augmentant le volume disponible, cette étape crée une baisse de pression supplémentaire permettant le changement d’état du CO2 supercritique vers un état gazeux ;
   6. une étape de sortie des matériaux carbonatés (516) ;
2. une étape (520) d’extraction du CO2 gazeux résiduel du compartiment inférieur vers le compartiment supérieur, intervenant entre l’étape d’entrée dans le compartiment inférieur (515) et l’étape de sortie des matériaux carbonatés (516) ;
3. une étape de liquéfaction du CO2 gazeux non piégé (530) ;
4. une étape de stockage dans le réservoir de CO2 liquide (540) ;
5. une étape de compression du CO2 liquide (550), à une pression supérieure à la pression critique, c’est-à-dire 73,7 bar ;
6. une étape de chauffage transcritique du CO2 (560), c’est-à-dire à une température supérieure à 31°C ;
7. une étape d’ajout de CO2 (570) , comprenant
   1. une étape d’ajout de complément de CO2, via le dispositif de dosage (571), par exemple une vanne ;
   2. une étape de mesure de la quantité de CO2 introduite via le dispositif de mesure (572), par exemple un débit-mètre ;

We observe, on the , a succession of particular steps of the process (50) which is the subject of the present invention. This process (50) for carbonating materials comprises:

1. a step (510) of carbonation of the materials, comprising:
   1. a step of entering and dosing the carbonated materials (511);
   2. a step of entering materials into the upper compartments of the reactor (512);
   3. an entry step into the main compartment (513);
   4. a main carbonation reaction step (514), inducing a drop in pressure in the main compartment;
   5. a step of entry into the lower compartment (515), linked to the opening of an operable trap, by increasing the available volume, this step creates an additional drop in pressure allowing the change of state of the supercritical CO2 towards a state gaseous;
   6. a step for releasing the carbonated materials (516);
2. a step (520) of extracting the residual gaseous CO2 from the lower compartment to the upper compartment, occurring between the step of entering the lower compartment (515) and the step of exiting the carbonated materials (516);
3. a step of liquefying the non-trapped CO2 gas (530);
4. a storage step in the liquid CO2 tank (540);
5. a step of compressing the liquid CO2 (550), at a pressure greater than the critical pressure, that is to say 73.7 bar;
6. a step of transcritical heating of the CO2 (560), that is to say at a temperature above 31°C;
7. a step of adding CO2 (570), comprising
   1. a step of adding additional CO2, via the dosing device (571), for example a valve;
   2. a step of measuring the quantity of CO2 introduced via the measuring device (572), for example a flow meter;

This method 50 is implemented, for example, by the device 10 described with regard to the .

Claims (7)

A material carbonation reactor (10), characterized in that it comprises:

1. A set of compartments of at least 3, stacked vertically and each separated from one another by an operable hatch, the main compartment (112) being positioned between two compartments.
2. One or more upper compartments (111) located above the main compartment (112);
3. One or more lower compartments (113), located below the main compartment (112);
4. an operable hatch (114) between the ambient air and the upper compartments (111), serving as an entry point for the materials to be carbonated;
5. an operable hatch (115) between the upper compartments (111) and the main compartment (112);
6. an operable hatch (116) between the main compartment (112) and the lower compartments (113);
7. an operable hatch (117) between the lower compartments (113) and the ambient air, serving as an outlet for carbonated materials;
8. A CO2 inlet for the main compartment, with a supply valve (118);
9. A CO2 outlet for the main compartment, with an exhaust valve (119);
10. An exhaust vent (120) in the upper compartments (111) located above the central compartment (112), with a pilot-operated and waterproof opening device;

1. A CO2 gas suction device (121) connecting the lower compartments (113) to the upper compartments (111), and comprising a transfer device (122);

Carbonation reactor (10) according to claim 1, for which the CO2 entering at the valve (118) is in the supercritical state, and in particular with a temperature greater than 31 °C and a pressure greater than 73.7 bar ; Carbonation reactor (10) according to claims 1 or 2, for which the materials to be carbonated are crushed recycled concrete waste having a humidity level greater than 5%, and with a particle size less than 80 mm; Device (20) for carbonating materials, characterized in that it comprises:

1. A liquid CO2 supply line comprising a flow rate dosing system (201) and a quantity measuring system (202) and opening onto a pressurized liquid CO2 tank (203);
2. A pressurized liquid CO2 tank (203);
3. A pressurized liquid CO2 pump (204) connected to the pressurized liquid CO2 tank (203) and to a gas/liquid type heat exchanger (220).
4. A gas/liquid type heat exchanger (220), allowing on the one hand heating of the gaseous CO2 remaining at the reactor outlet (210), and on the other hand the complementary heating of the liquid CO2
5. A pressurized liquid CO2 heater type heat exchanger (205), connected to the exchanger (220) and the reactor (210). This exchanger is also called a trans-critical exchanger;
6. A reactor (210) according to any one of claims 1 to 3, and comprising:
   1. A supercritical CO2 inlet for the main compartment, with a supply valve (218);
   2. A supercritical CO2 outlet for the main compartment, with an exhaust valve (219);
7. An additional gas/solid separator (206), with a watertight operable hatch (207);
8. A gaseous CO2 condenser type heat exchanger (208);
9. A set of pipes connecting the components, completing the CO2 circuit (209);

Device (20) according to claim 4, comprising a set of several reactors (210) connected in parallel and each operating with a time shift equivalent to the carbonation duration divided by the number of reactors (210); Device (30) for carbonating materials, according to claims 4 or 5 and comprising:

1. A carbonation device (301) comprising:
2. A carbonation reactor (310);
3. An exchanger (305) for heating the liquid CO2 entering the reactor (310);
4. An exchanger (308) for cooling and/or liquefying the gaseous CO2 leaving the reactor (310);
5. A heat pump circuit (302), comprising at least:
   1. A compressor (303);
   2. A relaxation device (304);
   3. A set of piping and accessories (305) transporting a working fluid between the different components of the circuit;

Process for carbonating materials (50), characterized in that it comprises:

1. a step (510) of carbonating the materials, carried out in a reactor for carbonating materials (10) according to one of claims 1, 2 or 3, comprising:

1. a step of entering and dosing the carbonated materials (511);
2. a step of entering materials into the upper compartments of the reactor (512);
3. an entry step into the main compartment (513);
4. a main carbonation reaction step (514);
5. an entry step into the lower compartment (515);
6. a step for releasing the carbonated materials (516);
7. a step (520) of extracting residual gaseous CO2 from the lower compartment to the upper compartment
8. a step of liquefying the non-trapped gaseous CO2 (530)
9. a storage step in the liquid CO2 tank (540)
10. a step of compressing the liquid CO2 (550)
11. a step of transcritical heating of CO2 (560)
12. a step of adding CO2 (570), comprising
    1. a step of adding additional CO2, via the dosing device (571)
    2. a step of measuring the quantity of CO2 introduced via the measuring device (572)