Carbon dioxide collector for a heating power plant

Abstract

The invention relates to a carbon dioxide collector (1) for a heating power plant (2), which is designed to separate carbon dioxide from the atmosphere (3), comprising at least the following components: - a paternoster mechanism (4) with at least one loading container (5); - a loading zone (6) for loading the at least one loading container (5) with a carbon dioxide absorption material (7); and - a discharge zone (8) for unloading the at least one loading container (5). The carbon dioxide collector (1) is characterized in particular by the fact that the loading zone (6) is arranged in the Earth's gravitational field (9) above the discharge zone (8). The carbon dioxide collector proposed here enables a cycle for separating carbon dioxide from air using a solid material that requires little personnel or equipment.

Description

[0001] The invention relates to a carbon dioxide collector for a heating power plant, a solar tower power plant with such a carbon dioxide collector, as well as a method with such a solar tower power plant for collecting carbon dioxide by means of a solar tower power plant.

[0002] There is a growing demand to actively filter out the excess carbon dioxide from the atmosphere, according to current knowledge. This process is also known as carbon capture. A variety of approaches are known for this. Currently, the costs and equipment required, as well as the monitoring and maintenance required, for such processes are very high. One interesting approach uses burnt lime (also called quicklime) as the raw material for absorbing carbon dioxide. First, the burnt lime [CaO] is mixed with water [H2O], whereby slaked lime (also called hydrated lime) [Ca(OH)2] is formed in an exothermic reaction. The slaked lime has a high affinity for absorbing carbon dioxide [CO2] (again in an exothermic reaction) and thus forming limestone [CaCO3].By means of lime burning or calcination, water and carbon dioxide are separated by applying high thermal energy (i.e., in an endothermic reaction), producing burnt lime. Absorbing carbon dioxide from the atmospheric air, with its relatively small proportion of carbon dioxide (approximately 0.04 vol%), is an extremely time-consuming process. Currently, the known method is to expose the slaked lime to the atmospheric air by spreading it on loading containers. However, transporting the lime from the loading containers is very labor-intensive in terms of personnel support and is therefore very costly.

[0003] Based on this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features of the invention are derived from the independent claims, for which advantageous embodiments are presented in the dependent claims. The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures, which comprise additional embodiments of the invention, can also be consulted for this purpose.

[0004] The invention relates to a carbon dioxide collector for a combined heat and power plant, which is designed to separate carbon dioxide from the atmosphere, comprising at least the following components: - a paternoster mechanism with at least one loading container; - a loading zone for loading the at least one loading container with a carbon dioxide absorption material; and - an unloading zone for unloading at least one loading container.

[0005] The carbon dioxide collector is characterized primarily by the fact that the loading zone is located above the unloading zone in the Earth's gravity field.

[0006] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve only to clearly distinguish them and do not reflect the order or ranking of the designated components. An ordinal number greater than one does not necessarily imply that another such component must be present.

[0007] The carbon dioxide collector proposed here is designed to convert the quasi-static dead-time element of the absorption process described above into a continuous or at least quasi-continuous step. For this purpose, a paternoster mechanism is used, in which at least one loading container, preferably a plurality of loading containers, is loaded with the carbon dioxide absorption material at the top of the Earth's gravity field, i.e., the loading zone is located at the top. The carbon dioxide absorption material in the respective loading container then moves downwards into the discharge zone, where it is discharged. This process can thus be carried out without personnel supervision and at a sufficiently slow rate for the required exposure time of the carbon dioxide absorption material. Furthermore, gravity is used to move the loading containers with very little external energy input (e.g., in the form of electrical energy).

[0008] It should be noted that the carbon dioxide absorption material can be any material known or yet to be developed. In one embodiment, the carbon dioxide absorption material is liquid; preferably, it is solid, particularly preferably in powder or bulk form. For example, the slaked lime mentioned above (or subsequently limestone and then burnt lime again) is suitable for such a cycle for capturing carbon dioxide from the atmospheric air. It should be noted that a material that adsorbs rather than absorbs can also be used.

[0009] It should be noted that the carbon dioxide collector can also be used in a carbon dioxide-generating process, for example, in a fossil-fuel power plant or a production facility. In this case, the atmosphere is not the Earth's atmosphere, but rather that of a (at least approximately) enclosed environment or process. The proportion of carbon dioxide in this process air is then sometimes considerably higher. Nevertheless, the carbon dioxide capture process in the carbon dioxide capture material is very slow, and therefore this quasi-continuous transport of the carbon dioxide capture material using the paternoster mechanism is very advantageous.

[0010] In one embodiment, the loading containers are loaded outside the paternoster mechanism in an upstream loading zone. The loading containers are then suspended in the paternoster mechanism and transported downwards. Preferably, in such an embodiment, the loading containers are unhooked at the bottom and unloaded at an unloading zone downstream of the paternoster mechanism.

[0011] It is further proposed in an advantageous embodiment of the carbon dioxide collector that the at least one loading container is rotated by the paternoster mechanism in a circular motion about an axis transverse to the earth's gravitational field, so that during the upward movement the top side of the loading container points downwards in the earth's gravitational field.

[0012] Unlike a traditional paternoster for moving people or materials upwards and downwards, this paternoster mechanism reverses the top and bottom surfaces of the loading containers during their upward movement. In an advantageous embodiment, the top of the loading container is designed (fully or partially) open, so that when the loading container changes from downward to upward movement, the loading container is emptied by gravity, specifically in the unloading zone, and in a smooth and slow movement. This prevents a sudden (avalanche-like) downward movement, or at least only occurs with small volume fractions of the total carbon dioxide absorption material contained in the emptying loading container.Likewise, in the loading zone, this inclination movement is advantageous for evening out the distribution of carbon dioxide absorption material introduced as bulk material and is at least harmless for liquid carbon dioxide absorption material.

[0013] It is further proposed in an advantageous embodiment of the carbon dioxide collector that the paternoster mechanism is arranged in a closed space in which the carbon dioxide absorption material is flowed against in counter-movement with air from the atmosphere via an inlet and an outlet.

[0014] In this embodiment, defined ventilation, and particularly preferably accelerated ventilation of the carbon dioxide absorption material by means of suitable ventilation, can be achieved. Ventilation can be actively achieved with a fan device and / or by means of the so-called chimney effect. The amount of atmospheric air flowing past is increased in this forced convection.

[0015] It is further proposed in an advantageous embodiment of the carbon dioxide collector that the inlet is arranged in the earth's gravitational field below the outlet.

[0016] In this embodiment, a counterflow is generated against the movement of at least one loading container. What matters here is not the change in relative velocity, but the high loading of the air flowing from the inlet with free carbon dioxide (air loading) and the equally high loading of the carbon dioxide absorption material with bound carbon dioxide (material loading) near the inlet. This makes the difference between the air loading and the material loading more uniform, thus enabling a higher yield of air overflow, and thus a higher separation rate.

[0017] It is further proposed in an advantageous embodiment of the carbon dioxide collector that the paternoster mechanism is gravity-driven.

[0018] In this embodiment, at least during normal operation, the paternoster mechanism is driven exclusively by the acceleration of the mass of the carbon dioxide absorption material. In a preferred embodiment, no active drive is provided, meaning the paternoster mechanism can be moved solely by filling (or mass absorption) the at least one loading container or by hand. For a suitable, slow speed, the paternoster mechanism is braked, for example.

[0019] It is further proposed in an advantageous embodiment of the carbon dioxide collector that the paternoster mechanism comprises an electrical generator by means of which the movement of the at least one loading container can be converted into electrical energy, wherein the electrical generator is preferably designed as a motor generator and is configured to move the at least one loading container, and / or wherein the electrical generator is preferably connected to an electrical accumulator for storing electrical energy.

[0020] In this embodiment, an electric generator is used, which preferably acts as the sole braking device, or in normal operation, the only braking device, on the gravity drive of the paternoster mechanism (which preferably acts exclusively as described above). This allows additional electrical energy to be generated, for example, due to the very slow movement and the need to increase the speed to a significantly higher minimum speed solely for operating control elements of the carbon dioxide collector, such as opening flaps at the inlet and / or outlet.

[0021] In an embodiment of the generator as a motor generator, it can also be used to set the paternoster mechanism or even to drive it, for example during idle or maintenance operation.

[0022] In one embodiment, the alternatively or additionally generated electrical energy can be fed into an electrical accumulator and thus used for other processes with a delay.

[0023] According to a further aspect, a solar tower power plant with a carbon dioxide collector according to an embodiment as described above is proposed, comprising at least the following components: - a solar tower to capture concentrated solar rays; - a reflector field for reflecting solar rays onto the solar tower; and - a furnace for heating carbon dioxide absorption material, which is operable with the concentrated solar rays of the solar tower, wherein in order to release the absorbed carbon dioxide from the carbon dioxide absorption material which has been loaded in the carbon dioxide collector, the concentrated solar rays of the solar tower are directed to heat this carbon dioxide absorption material.

[0024] The carbon dioxide collector with paternoster mechanism is particularly advantageous when used in a combined heat and power plant designed as a solar tower power plant. Such a solar tower power plant is capable of directly generating a temperature from solar radiation onto the Earth's surface (by means of directed reflection concentrated in the solar tower) that is sufficient, for example, to calcine, i.e., burn, limestone. Such a temperature is approximately 900 °C [nine hundred degrees Celsius]. This avoids the lossy conversion of thermal radiation into electrical energy and its subsequent conversion back into heat energy. Instead, in a (solar) furnace, the thermal radiation is used directly to heat and thus calcine the limestone. The reflector array and the solar tower, for example, are designed (at least functionally) conventionally.Preferably, the individual reflectors (e.g., glass mirror panes, preferably parabolic in shape) are designed to be movable so as to track the position of the sun. In one embodiment, the solar rays concentrated in the receiver of the solar tower are directed directly onto the limestone or onto a heating surface, by means of which a cavity of the furnace can be heated to a desired temperature. Alternatively or additionally, a heat transfer medium, such as liquefied salt, is used to transport the generated heat between the solar tower and the calcination furnace.

[0025] It is further proposed in an advantageous embodiment of the solar tower power plant that the carbon dioxide absorption material is present as bulk material and that the solar tower power plant further comprises a mill for crushing sintered bulk material, wherein the mill is preferably arranged at the top of the solar tower, at the top of the carbon dioxide collector and / or at a level above between the solar tower and the carbon dioxide collector with respect to the earth's gravity field.

[0026] In this advantageous embodiment, a mill is further provided, by means of which solid carbon dioxide absorption material prepared as bulk material can be converted back into a suitably fine grain size, provided the bulk material has sintered into larger lumps. This step is preferably carried out after heating the carbon dioxide absorption material in the furnace operated by the solar tower (e.g., the calcination of limestone), because the strength of the unloaded carbon dioxide absorption material (e.g., burnt or slaked lime) is significantly lower than that of the loaded carbon dioxide absorption material (e.g., limestone). For example, sintered limestone at least partially disintegrates spontaneously into a finer grain size during calcination.A fine grain size is advantageous for creating a large surface area with which the carbon dioxide absorption material (e.g., slaked lime) is exposed to the carbon dioxide and can react. This increases the efficiency of the separation process in the carbon dioxide collector. Alternatively or additionally, the (then still loaded) carbon dioxide absorption material (e.g., limestone) is ground or crushed before heating (e.g., calcination), so that the heat from the furnace is distributed more quickly throughout the carbon dioxide absorption material, thus requiring less heat and / or enabling faster processing times.

[0027] In an advantageous embodiment, the mill is arranged at the top of the solar tower of the solar tower power plant, in the Earth's gravity field. In an advantageous embodiment, the mill is arranged at the top of the carbon dioxide collector, in the Earth's gravity field. Alternatively or additionally (in the case of multiple mills), one of the mills is arranged in a plane at the height of the top of the solar tower and the top of the carbon dioxide collector. This may reduce the cost of transporting the carbon dioxide absorption material.

[0028] It is further proposed in an advantageous embodiment of the solar tower power plant that the furnace is designed for continuous or quasi-continuous passage with the carbon dioxide absorption material from the carbon dioxide collector.

[0029] In this embodiment, the furnace is also configured for a continuous or quasi-continuous process step. This also requires minimal maintenance and is therefore cost-effective to operate.

[0030] Preferably (regardless of the respective embodiment), the mass flow in the cycle between the carbon dioxide collector and the kiln (and optionally the mill and other intermediate steps, such as the slaking of burnt lime), for example the mass flow of the carrier material of the carbon dioxide absorption material, is (at least according to the design) constant. For example, when using lime as the carbon dioxide absorption material, the mass flow of calcium [Ca] is constant. This means that, for example, the relatively rapid heating and reprocessing of the carbon dioxide absorption material only processes a small amount. In the carbon dioxide collector, on the other hand, with the significantly longer residence time, a large amount of carbon dioxide absorption material is stored (and exposed to the air), with an amount being fed in (unloaded) and discharged (loaded) corresponding to the amount required for the other process steps.For example, the loading itself is not considered as a controlled variable (disturbance), but rather the focus is on a constant flow rate. Alternatively or additionally, the loading is controlled, for example, by differential measurement of the carbon dioxide contained in the air at the inlet and outlet of the carbon dioxide collector. Alternatively or additionally, the air flow rate is controlled accordingly.

[0031] In an advantageous embodiment, the water that may be used and dissolved again during heating (for example during calcination) is at least largely collected in the kiln and reused for the processing of the carbon dioxide absorption material (for example during slaking of the burnt lime).

[0032] It is further proposed in an advantageous embodiment of the solar tower power plant that the solar tower comprises an elevator for carbon dioxide absorption material and that the furnace is arranged at the top of the solar tower with respect to the Earth's gravitational field.

[0033] In this embodiment, an elevator is provided to transport the carbon dioxide absorption material, which has been moved downwards by the paternoster mechanism (and loaded), into a furnace, which is preferably located directly at the top of the solar tower, for reprocessing. The elevator is also equipped with a paternoster mechanism, for example, and preferably also has a downward transport function for the carbon dioxide absorption material. For example, during the downward transport, the carbon dioxide absorption material is made ready for reabsorption. For example, when using lime (burned in a kiln), this is loaded with water (i.e., slaked).A paternoster mechanism with both upward and downward transport can be operated with very low energy consumption, whereby in the case of lime as carbon dioxide absorption material and similar process materials, with early recycling of the carbon dioxide absorption material (burnt lime) heat-treated in the furnace of the solar tower, even the material to be transported downwards (slaked lime) is only slightly lighter than the material to be transported upwards (limestone).

[0034] According to a further aspect, a method for collecting carbon dioxide by means of a solar tower power plant according to an embodiment as described above is proposed, comprising at least the following steps, which are carried out in a cycle in the order mentioned: a. Carbon dioxide absorption material is filled into one of the loading containers in the loading zone of the carbon dioxide collector; b. Air comprising carbon dioxide is flowed over at least one cargo container; c. the carbon dioxide absorption material in its loading container is moved downwards by gravity using the paternoster mechanism; d. the carbon dioxide absorption material is transported from the unloading zone, preferably by means of an elevator according to an embodiment as described above in the solar tower upwards, into the furnace, e. the carbon dioxide absorption material is heated in the furnace by means of concentrated solar rays; and f. the carbon dioxide absorption material heated in the furnace is fed to the loading zone of the carbon dioxide collector, wherein preferably before step f. the carbon dioxide absorption material is comminuted by means of a mill according to an embodiment according to the above description.

[0035] Reference is made here to the description of the process steps in connection with the solar tower power plant. Regarding step b, it should be added that the air flows past at least one loading container passively, inlet-controlled or outlet-controlled passively, and / or actively. For example, the residual heat or the heat from the exothermic reaction during the processing of the carbon dioxide absorption material is used to create or support a chimney effect for the passing air.

[0036] Regarding step e, it should be added that the concentrated solar rays are either directed directly onto the loaded carbon dioxide absorption material, directed onto a furnace wall to indirectly heat the loaded carbon dioxide absorption material, and / or the loaded carbon dioxide absorption material can be heated in the furnace indirectly via a carrier medium (e.g., liquefied salt). For continuous temperature control, the last two variants are preferred, whereby, for example, the furnace wall can be cooled and / or the energy density of the concentrated solar rays can be controlled.

[0037] Furthermore, it should be noted that the carbon dioxide captured in the furnace is preferably sequestered or further utilized. For example, it can be sequestered in basalt rock and / or reprocessed, for example, into methane or methanol as a synthetic fuel, for example, so-called e-fuels.

[0038] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, whereby it should be noted that the drawings are not to scale and are not suitable for defining proportions. It is shown in Fig. 1: a solar tower power plant with a carbon dioxide collector.

[0039] In Fig.1 schematically shows a heating and power plant 2 designed as a solar tower power plant 16 with a carbon dioxide collector 1. The solar tower 17 of the solar tower power plant 16 is, for example, designed (at least functionally) conventionally, with a reflector field 19 consisting of a plurality of individual reflectors directing the sun's rays 18 in a concentrated manner onto the top of the solar tower 17. In this embodiment, a furnace 20 for recycling carbon dioxide absorption material 7 is arranged directly at the top of the solar tower 17, i.e., at the top in the Earth's gravitational field 9. In addition, an elevator 22 for carbon dioxide absorption material 7 is provided (purely optionally) within the solar tower 17. Alternatively or additionally, a separate tower (for example, with regard to the shadow cast) is arranged behind the solar tower 17. In the furnace 20, the (previously) loaded carbon dioxide absorption material 7 is discharged again, i.e. the carbon dioxide is separated.Using lime as the carbon dioxide absorption material 7, supplied limestone is burned (calcined), thus producing burnt lime or quicklime. Subsequently, it is slaked with water, for example, immediately after calcination, thus producing slaked lime or hydrated lime. For this purpose, the carbon dioxide collector 1 comprises a water supply 25, by means of which the water can be applied to the burnt lime between the kiln 20 and the paternoster mechanism 4.

[0040] By means of the first transport device 23, the discharged (preferably already recycled) carbon dioxide absorption material 7 is transported to the carbon dioxide collector 1. The carbon dioxide collector 1 comprises a paternoster mechanism 4, by means of which a plurality of loading containers 5 are moved downwards and upwards, preferably solely by means of the forces resulting from gravity as a result of the loading. It should be noted that here (purely optionally) the loading containers 5 are rotated once during the cyclical movement so that (in the illustration on the left) the top faces downwards.

[0041] In the loading zone 6 located at the top of the Earth's gravity field 9, the processed carbon dioxide absorption material 7 is unloaded into one of the loading containers 5. Following gravity, for example, braked by a counter-torque of a (purely optionally provided) generator 13, the loaded loading container 5 is slowly transported downwards to the unloading zone 8 below. In the unloading zone 8, unloading takes place onto a second transport device 24, here also by means of the intrinsic tilting movement of the loading container 5.

[0042] In the chamber 10 of the carbon dioxide collector 1 (which is purely optionally closed off from the atmosphere 3), air from the atmosphere 3 (for example, the earth or a process environment in a carbon dioxide-generating industrial plant) is admitted via an inlet 11, which here (purely optionally) is arranged below in the earth's gravitational field 9 or near the unloading zone 8, and flows past the loading containers 5. As a rule, only a portion of the carbon dioxide contained in the air is taken up, for example, absorbed, by the carbon dioxide absorption material 7. The air, with (at least somewhat less) carbon dioxide, is released back into the atmosphere 3 (for example, in the case of an industrial plant, now into the outside environment or a downstream location) via the outlet 12, whereby the outlet 12 is arranged here (purely optionally) above in the earth's gravitational field 9 or near the loading zone 6.The inlet 11 and the outlet 12 are arranged at least in such a way that a flow of air is guided over the filled loading containers 5.

[0043] It should be noted that the carbon dioxide collector 1 only optionally includes a closed space 10. Alternatively, the paternoster mechanism 4, or at least the downwardly moving loading containers 5, are arranged openly in the atmosphere 3.

[0044] By means of the (purely optional) generator 13, electrical energy can be generated from the downward movement of the filled loading containers 5, which is optionally stored in an accumulator 15. Furthermore, the generator 13 is optionally designed as a motor generator 14, so that the paternoster mechanism 4 can be moved during maintenance work or other operating modes.

[0045] By means of the second transport device 24, the loaded carbon dioxide absorption material 7 (for example limestone) is transported to the furnace 20 or, in this case, initially to the elevator 22.

[0046] In an optional embodiment, a mill 21 is further provided, by means of which the discharged carbon dioxide absorption material 7 (for example, the burnt or slaked lime) can be brought to a desired grain size.

[0047] The carbon dioxide collector proposed here enables a cycle for separating carbon dioxide from air using a solid that requires little personnel and equipment.

Claims

[1] Carbon dioxide collector (1) for a thermal power plant (2), which is designed to separate carbon dioxide from the atmosphere (3), comprising at least the following components: - a paternoster mechanism (4) with at least one loading container (5); - a loading zone (6) for loading the at least one loading container (5) with a carbon dioxide absorption material (7); and - an unloading zone (8) for unloading the at least one loading container (5), characterized by that the loading zone (6) is arranged in the earth's gravity field (9) above the unloading zone (8). [2] Carbon dioxide collector (1) according to claim 1, wherein the paternoster mechanism (4) is arranged in a closed space (10) in which the carbon dioxide absorption material (7) is flowed in counter-movement with air from the atmosphere (3) via an inlet (11) and an outlet (12). [3] Carbon dioxide collector (1) according to claim 2, wherein the inlet (11) is arranged in the earth's gravitational field (9) below the outlet (12). [4] Carbon dioxide collector (1) according to one of the preceding claims, wherein the paternoster mechanism (4) is gravity-operated. [5] Carbon dioxide collector (1) according to one of the preceding claims, wherein the paternoster mechanism (4) comprises an electrical generator (13) by means of which the movement of the at least one loading container (5) can be converted into electrical energy, wherein the electric generator (13) is preferably designed as a motor generator (14) and is arranged to move the at least one loading container (5), and / or wherein the electric generator (13) is preferably connected to an electric accumulator (15) for storing electrical energy. [6] Solar tower power plant (16) with a carbon dioxide collector (1) according to one of the preceding claims, comprising at least the following components: - a solar tower (17) for collecting concentrated solar rays (18); - a reflector field (19) for reflecting solar rays (18) directed onto the solar tower (17); and - a furnace (20) for heating carbon dioxide absorption material (7), which furnace is operable with the concentrated solar rays (18) of the solar tower (17), wherein in order to release the absorbed carbon dioxide from the carbon dioxide absorption material (7) which has been loaded in the carbon dioxide collector (1), the concentrated solar rays (18) of the solar tower (17) are directed to heat this carbon dioxide absorption material (7). [7] Solar tower power plant (16) according to claim 6, wherein the carbon dioxide absorption material (7) is in the form of bulk material and the solar tower power plant (16) further comprises a mill (21) for comminuting sintered bulk material, wherein the mill (21) is preferably arranged at the top of the solar tower (17), at the top of the carbon dioxide collector (1) and / or at a level above between the solar tower (17) and the carbon dioxide collector (1) with respect to the earth's gravitational field (9). [8] Solar tower power plant (16) according to claim 6 or claim 7, wherein the furnace (20) is arranged to be continuously or quasi-continuously fed with the carbon dioxide absorption material (7) from the carbon dioxide collector (1). [9] Solar tower power plant (16) according to one of claim 6 to claim 8, wherein the solar tower (17) comprises an elevator (22) for carbon dioxide absorption material (7) and the furnace (20) is arranged at the top of the solar tower (17) with respect to the earth's gravitational field (9). [10] A method for collecting carbon dioxide by means of a solar tower power plant (16) according to any one of claims 6 to 9, comprising at least the following steps, which are carried out in a cycle in the order mentioned: a. Carbon dioxide absorption material (7) is filled into one of the loading containers (5) in the loading zone (6) of the carbon dioxide collector (1); b. Air comprising carbon dioxide is flowed over at least one loading container (5); c. the carbon dioxide absorption material (7) in its loading container (5) is moved downwards by gravity by means of the paternoster mechanism (4); d. the carbon dioxide absorption material (7) is transported from the unloading zone (8), preferably by means of an elevator (22) according to claim 9 in the solar tower (17) upwards into the furnace (20), e. the carbon dioxide absorption material (7) is heated in the furnace (20) by means of the concentrated solar rays (18); and f. the carbon dioxide absorption material (7) heated in the furnace (20) is fed to the loading zone (6) of the carbon dioxide collector (1), wherein preferably before step f. the carbon dioxide absorption material (7) is comminuted by means of a mill (21) according to claim 7.

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