Apparatus for separating carbon dioxide from ambient air, method for operating such apparatus and controller

Abstract

The present invention relates to an apparatus (100) for separating carbon dioxide (C) from ambient air (A). The apparatus (100) includes an absorption chamber (110) having a sealable air inlet (112) for allowing ambient air (A) to enter, a sealable air outlet (114) for discharging outlet air (B) with reduced carbon dioxide, and a sealable carbon dioxide outlet (116) for discharging carbon dioxide (C). Furthermore, the apparatus (100) includes an absorbent (120) arranged in the absorption chamber (110) and configured to cause reversible adsorption of carbon dioxide (C) from ambient air (A) at the absorbent (120). The apparatus (100) further includes at least one conveying device (130) configured to convey ambient air (A) into the absorption chamber (110), convey outlet air (B) from the absorption chamber (110), evacuate the absorption chamber (110), and convey carbon dioxide (C) from the absorption chamber (110). The device (100) also includes a temperature control device (140) configured to adjust the temperature of the absorbent (120) to induce the desorption of carbon dioxide (C) absorbed at the absorbent (120). The device (100) further includes at least one electrochemical gas sensor (150) configured to detect at least one oxygen-dependent measurement parameter in the absorption chamber (110).

Description

Technical Field

[0001] This invention relates to an apparatus for separating carbon dioxide from ambient air, a method for operating such an apparatus, and a controller, according to the preamble of the independent claim. The subject of this invention is also a computer program. Background Technology

[0002] The process known as Direct Air Capture (DAC) describes the removal of carbon dioxide from the atmosphere. DAC processes are traditionally carried out in a particularly time-controlled manner, where sufficient process time can be set until the corresponding subprocesses reliably terminate, which can result in a degree of inefficiency in equipment utilization. Summary of the Invention

[0003] In this context, utilizing the proposed solution herein, an apparatus for separating carbon dioxide from ambient air, a method for operating such apparatus, a corresponding controller, and a corresponding computer program are envisioned according to the main claim. Advantageous improvements and refinements to the apparatus specified in the independent claim can be achieved through the measures enumerated in the dependent claims.

[0004] According to the implementation method, suitable gas sensors (e.g., automotive gas sensors) can be used in the DAC equipment to detect and regulate oxygen-based state parameters and process time points. In other words, it is particularly proposed to use gas sensors (e.g., automotive exhaust gas sensors) to detect relevant switching conditions in the DAC equipment instead of time control. For this purpose, an integrated electrochemical gas sensor (e.g., automotive exhaust gas sensor or automotive electrochemical exhaust gas sensor) can be specifically provided to measure the excess or deficiency of oxygen, in the form of oxygen or carbon dioxide in the air, in close proximity and directly in the process fluid in the DAC equipment, so as to enable targeted system regulation. For example, sensors similar to or corresponding to known broadband oxygen detectors, abrupt oxygen detectors, or nitrogen oxide sensors (NOx sensors) can be used.

[0005] Compared to systems that do not directly determine or measure oxygen or carbon dioxide content as characterizing system parameters, or compared to determining them using costly measurement methods, integrating at least one gas sensor (e.g., an automotive exhaust gas sensor or an electrochemical exhaust gas sensor) enables cost-effective system conditioning and performance optimization of DAC equipment. As a basis for such sensors, proven broadband oxygen detectors, jump-type oxygen detectors, or NOx sensors can be used, by way of example. The main advantages of using suitable gas sensors in DAC equipment include: simplifying the sensing devices in the DAC equipment; detecting and adhering to pre-defined limits for process steps; directly detecting key (especially oxygen-based) system state points (when these state points should trigger subsequent process steps), which enables improved dynamic behavior and more efficient equipment loading, where investment costs can be distributed across more operating hours; and optimized operation management, thereby improving efficiency and reducing degradation.

[0006] A device for separating carbon dioxide from ambient air is envisioned, wherein the device has the following characteristics: An absorption chamber for receiving an absorbent, the absorption chamber having a sealable air inlet for allowing (carbon dioxide-rich) ambient air to enter the absorption chamber, a sealable air outlet for discharging (low carbon dioxide) outlet air from the absorption chamber, and a sealable carbon dioxide outlet for discharging carbon dioxide from the absorption chamber. At least one conveying device is configured to convey ambient air into the absorption chamber, convey outlet air from the absorption chamber, evacuate the absorption chamber, and convey carbon dioxide from the absorption chamber. A temperature control device, configured to adjust the temperature of the absorbent so as to cause the carbon dioxide absorbed at the absorbent to desorb from the absorbent; and At least one electrochemical gas sensor configured to detect at least one oxygen-dependent measurement parameter in an absorption chamber.

[0007] The device may also be referred to as a CO2 separation device, DAC device, DAC equipment, or DAC system, where DAC stands for Direct Air Capture. At least one oxygen-dependent measurement parameter may be the partial pressure of oxygen. At least one oxygen-dependent measurement parameter may relate to carbon dioxide and be correlated with the partial pressure of oxygen, the amount of oxygen, or other oxygen-dependent sensor signals. When using at least one oxygen-dependent measurement parameter, oxygen can be detected directly and carbon dioxide can be detected indirectly, optionally as an additional method.

[0008] Preferably, the absorbent is arranged in the absorption chamber between the air inlet and the air outlet, wherein the absorbent is configured to reversibly adsorb carbon dioxide from the surrounding ambient air at the absorbent location. The absorbent, or absorption agent, is preferably an adsorbent or adsorption agent.

[0009] It is clear here that the ambient air is richer in carbon dioxide than the exhaust air where carbon dioxide has been reduced.

[0010] According to one embodiment, at least one electrochemical gas sensor can be configured to detect at least one oxide-dependent measurement parameter in an absorption chamber. This embodiment offers the advantage of directly detecting oxygen bound in oxygen compounds and therefore also directly detecting carbon dioxide.

[0011] At least one electrochemical gas sensor can also have potentiometric and, as an additional or alternative, amperometric detection principle. Such an implementation offers the advantage of being able to use commonly used, accurate, and advantageous sensor types.

[0012] Furthermore, at least one electrochemical gas sensor can include an exhaust gas sensor, an exhaust gas sensor for motor vehicles, a nitrogen oxide sensor, an oxygen detector, a broadband oxygen detector, and a jump-type oxygen detector as an additional or alternative solution. In other words, at least one electrochemical gas sensor can include an exhaust gas sensor, wherein the exhaust gas sensor can be a sensor suitable for or commonly used in motor vehicles, such as a nitrogen oxide sensor, an oxygen detector, a broadband oxygen detector, and a jump-type oxygen detector as an additional or alternative solution. Such an implementation provides the advantage of being able to use reliable, proven, and readily available sensor types.

[0013] Furthermore, the device can have multiple electrochemical gas sensors. Here, at least one first gas sensor can be arranged in the inlet area, and at least one second gas sensor can be arranged in the outlet area. This implementation provides the advantage of enabling particularly rapid and accurate detection of at least one measurement parameter.

[0014] In one embodiment, at least a subset of gas sensors can belong to the same sensor type. Alternatively, at least a subset of gas sensors can have different sensor types. This embodiment offers the advantage that different sensor configurations adapted to the specific application can be selected.

[0015] In particular, at least one of the electrochemical gas sensors is a nitrogen oxide sensor. Such an implementation provides the advantage of being able to easily, reliably, and accurately detect oxygen-dependent measurement parameters as well as, as an additional option, oxide-dependent measurement parameters.

[0016] Furthermore, at least one electrochemical gas sensor can be configured to detect, as a measurement parameter, the partial pressure of carbon dioxide at the inlet and the partial pressure of carbon dioxide at the outlet, the relationship between which represents the switching conditions for controlling the air inlet, air outlet, and at least one delivery device in the case of absorbent saturation with carbon dioxide. Such switching conditions can also be referred to as the first switching conditions. This implementation provides the advantage that the condition of absorbent saturation with carbon dioxide can be reliably and accurately identified, and subsequently, a corresponding appropriate response can be made to the control or regulation of the device.

[0017] At least one electrochemical gas sensor can also be configured to detect, as a measurement parameter, the partial pressure of oxygen in the absorption chamber, whose relationship with a predefined limit value represents the switching conditions for controlling at least one delivery device and temperature control device in the case of a vacuum-sealed absorption chamber. Such switching conditions can also be referred to as second switching conditions. This implementation provides the advantage of being able to quickly and reliably determine when the absorption chamber is sufficient, and to respond accordingly in a suitable manner to the control or regulation of the device.

[0018] Furthermore, at least one electrochemical gas sensor can be configured to detect, as a measurement parameter, the partial pressure of oxygen at the carbon dioxide outlet and, as an additional or alternative, the partial pressure of carbon dioxide. The relationship between these parameters and a predefined threshold represents the switching conditions for controlling the temperature control device, at least one delivery device, the air inlet, the air outlet, and the carbon dioxide outlet upon termination of desorption. Such switching conditions can also be referred to as third switching conditions. This implementation offers the advantage of reliably and accurately determining when desorption begins and thus when carbon dioxide acquisition ends and when carbon dioxide adsorption begins, thus allowing for a corresponding and appropriate response in terms of device control or regulation.

[0019] A method for implementing the device mentioned herein is also envisioned, wherein the method comprises the following steps: The sensor signal of at least one electrochemical gas sensor is read in, wherein the sensor signal represents at least one oxygen-dependent measurement parameter in the absorption chamber detected by at least one electrochemical gas sensor; and The air inlet, air outlet, carbon dioxide outlet, at least one delivery device, and / or temperature control device are controlled based on the sensor signals read in the reading step.

[0020] Therefore, it is possible to detect oxygen-based operating cycle points in DAC equipment, especially with the help of suitable gas sensing devices (such as automotive sensors or exhaust gas sensors), in order to optimize equipment operation and improve equipment efficiency.

[0021] In one embodiment, a machine learning algorithm can be used for the measurement parameters during the read-in step, employing multiple linear regression, neural networks, and Gaussian processes as additional or alternative schemes. Here, the algorithm can be trained using training data to estimate the measurement error of at least one electrochemical gas sensor at different operating points of the device. This embodiment offers the advantage that the accuracy of the detected measurement parameters can be further improved for additional use during operation.

[0022] This method can be implemented, for example, in software, hardware, or a hybrid of software and hardware, such as in a controller or device.

[0023] The proposed solution here further implements a controller configured to execute, manipulate, or implement the steps of a variation of the proposed method in a corresponding device. This design variation of the invention, in the form of a controller, also enables the rapid and efficient achievement of the objectives upon which the invention is based. The controller can be part of a system that also includes the device.

[0024] To this end, the controller may have at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface for reading sensor signals from a sensor or for outputting control signals to an actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a microcontroller, or the like, and the memory unit may be flash memory or magnetic memory. The communication interface may be configured for wirelessly and / or wiredly reading or outputting data, wherein a wired data reading or output communication interface may, for example, electrically or optically read or output such data from or to a corresponding transmission line.

[0025] A controller can currently be understood as an electronic device that processes sensor signals and outputs control and / or data signals based on those signals. The controller can have an interface, which can be constructed in hardware and / or software. In a hardware-based construction, the interface can be, for example, part of a so-called system-specific integrated circuit (ASIC) that contains various functions of the controller. However, it is also possible for the interface to be self-contained, an integrated switching circuit, or at least partially composed of discrete components. In a software-based construction, the interface can be a software module, which exists, for example, on a microcontroller alongside other software modules.

[0026] It is also advantageous to have a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium (such as semiconductor memory, hard disk memory or optical memory), and especially when the program product or program is implemented on a computer or device, the program code is used to perform, implement and / or manipulate the steps of the method according to one of the embodiments described above. Attached Figure Description

[0027] Embodiments of the scheme conceived herein are shown in the accompanying drawings and explained in more detail in the following description. Wherein: Figure 1 A schematic diagram of one embodiment of a device for separating carbon dioxide from ambient air is shown. Figure 2 Showing from Figure 1 A schematic diagram of an embodiment of the gas sensor of the device; Figure 3 Showing from Figure 1 A schematic diagram of an embodiment of the gas sensor of the device; Figure 4 Showing from Figure 1 A schematic diagram of an embodiment of the gas sensor of the device; Figure 5 A flowchart is shown as an embodiment of a method for operating a device for separating carbon dioxide from ambient air. Figure 6 A schematic diagram of one embodiment of the controller is shown; and Figure 7 It shows the relationship with the source Figure 5 The flowchart shows the process of combining the methods. Detailed Implementation

[0028] In the following description of advantageous embodiments of the invention, the same or similar reference numerals are used for elements shown in different figures and those that function similarly, wherein repeated descriptions of these elements are omitted.

[0029] Figure 1 A schematic diagram of one embodiment of a device 100 for separating carbon dioxide C from ambient air A is shown. Device 100 can also be referred to as equipment or apparatus or system for so-called direct air capture. Device 100 is constructed to perform a direct air capture process. Such a process is explained in more detail below.

[0030] exist Figure 1 The diagram exemplarily shows only the absorption chamber 110, air inlet 112, air outlet 114, carbon dioxide outlet 116, absorbent 120, at least one delivery device 130, temperature control device 140, and at least one gas sensor 150 of the device 100.

[0031] Absorption chamber 110 (which may also be referred to as an absorption chamber or similar) includes an air inlet 112, an air outlet 114, and a carbon dioxide outlet 116. The air inlet 112, air outlet 114, and carbon dioxide outlet 116 can be closed, or can be closed independently of each other. Here, when the air inlet 112, air outlet 114, and carbon dioxide outlet 116 are all closed, the absorption chamber 110 is a closed space relative to the surrounding environment. The air inlet 112 is configured to allow ambient air A rich in carbon dioxide to enter the absorption chamber 110. The air outlet 114 is configured to discharge outlet air B, which has reduced or lower carbon dioxide levels, from the absorption chamber 110. The carbon dioxide outlet 116 is configured to discharge carbon dioxide (CO2) C from the absorption chamber. If water is co-absorbed based on the properties of the absorbent, the water is also guided through this outlet. Alternatively, the air outlet 114 and carbon dioxide outlet 116 can also be physically identical.

[0032] In the absorption chamber 110, an absorbent 120 is arranged between an air inlet 112 and an air outlet 114. The absorbent 120 is configured to cause the reversible adsorption of carbon dioxide C from the surrounding ambient air A at the absorbent 120 location.

[0033] The device 100 further includes at least one conveying device 130. The conveying device 130 is configured to deliver ambient air A into the absorption chamber 110, deliver outlet air B from the absorption chamber 110, evacuate the absorption chamber 110, and optionally, as an additional option, deliver carbon dioxide C from the absorption chamber 110. The at least one conveying device 130 includes, for example, at least one fan and / or at least one pump.

[0034] The temperature control device 140 is configured to adjust the temperature of the absorbent 120, particularly to heat it, for example, to 100 °C, so as to cause the carbon dioxide C absorbed at the absorbent 120 to desorb from the absorbent 120. The desorbed carbon dioxide C can then be guided away through the carbon dioxide outlet 116.

[0035] The device 100 further includes at least one gas sensor 150, which is implemented as an electrochemical gas sensor. The at least one gas sensor 150 is configured to detect at least one oxygen-dependent measurement parameter in the absorption chamber 110. The at least one gas sensor 150 is, for example, arranged in the absorption chamber 110. Alternatively, the at least one gas sensor 150 is hydrodynamically connected to the absorption chamber 110.

[0036] In particular, the at least one electrochemical gas sensor 150 is also configured to detect at least one oxide-dependent measurement parameter in the absorption chamber 110. The at least one electrochemical gas sensor 150 has, for example, a potentiometric and / or amperometric detection principle. Here, the at least one electrochemical gas sensor 150 may be, for example, an exhaust gas sensor, an exhaust gas sensor for motor vehicles, a nitrogen oxide sensor, an oxygen detector, a broadband oxygen detector, and / or a jump-type oxygen detector, or be implemented as such a sensor.

[0037] According to one embodiment, the device 100 includes a plurality of electrochemical gas sensors 150. At least one first gas sensor 150 of the plurality of gas sensors 150 is arranged in the region of inlet 112. At least one second gas sensor 150 of the plurality of gas sensors 150 is arranged in the region of outlet 114. Furthermore, according to one embodiment, at least one subset of the gas sensors 150 belongs to the same sensor type. As an additional or alternative embodiment, at least one subset of the gas sensors 150 may have different sensor types. In particular, according to one embodiment, at least one of the electrochemical gas sensors 150 is a nitrogen oxide sensor or includes such a nitrogen oxide sensor.

[0038] DAC (Direct Air Capture) involves the removal of CO2 from the atmosphere (here, ambient air A). Ambient air A is drawn in through a collector or absorption chamber 110 using a fan or conveyor 130, and the CO2 is collected on the surface of a highly selective filter material or absorbent 120 located inside the collector. Once the filter material is filled with CO2, the collector (more precisely, the air inlet 112 and air outlet 114) is closed, first evacuated, and then heated to approximately 100 °C. Under these conditions, the CO2 bound in the absorbent 120 is desorbed and pumped out of the collector (through carbon dioxide outlet 116), and can now be used outside the DAC equipment, for example, by mixing with a carrier medium (such as H2O) and pumping it deep underground for storage, or in other processes requiring CO2 (such as in the power-to-X technology for the production of synthetic fuels). The DAC process differs from traditional methods in that it is not implemented in a time-controlled manner, but rather controlled or regulated by the sensor signal of at least one gas sensor 150, which improves the efficiency of equipment utilization.

[0039] Because adsorption and desorption occur separately in time, the gas flow from both processes can be analyzed using at least one measurement unit, or at least one gas sensor 150, through appropriate sampling and piping guidance. For example, the CO2 inlet and outlet concentrations during adsorption can also be measured using at least one gas sensor 150 by alternately guiding the gas sample from the inlet and outlet paths to at least one gas sensor 150. Since the adsorption process proceeds slowly and the inlet concentration remains almost constant over time, this approach is inherently less prone to error.

[0040] A report from the IPCC (International Panel on Climate Change) concludes that urgent climate protection measures are necessary to halve emissions by 2030. To achieve this, not only must emissions be drastically reduced, but older CO2 emissions must also be removed from the atmosphere. To permanently remove this separated CO2, direct air detection (DAC) technology must be combined with CO2 storage technology to reliably seal it underground, for example. The advantages of direct air detection, or direct air capture, are listed below. DAC is location-independent: CO2 concentrations in the atmosphere are the same worldwide. This means that DAC equipment can be deployed anywhere because it does not need to be connected to emission sources. The DAC equipment should only be placed near renewable energy sources and where CO2 can be stored. DAC is highly scalable and measurable: the equipment is based on a modular technological concept, making it highly scalable. Furthermore, it is possible to accurately measure how much CO2 the equipment separates. DAC enables efficient land use: the equipment requires less land than other technologies. On an area of ​​0.42 hectares, it is possible to remove, for example, 4,000 tons of CO2 from the air annually, which is almost 1,000 times more effective than trees. On the same area, approximately 220 trees, each with an estimated capacity of 22 kg, would be planted, meaning only 4.62 tons of CO2 per year.

[0041] Figure 2 Showing from Figure 1 A schematic diagram of one embodiment of a gas sensor 150 in the device. The gas sensor 150 is implemented as a nitrogen oxide sensor or NOx sensor, as is known, for example, in motor vehicle technology or in a similar manner. This type of gas sensor 150 can be used as one, multiple, or all gas sensors in the device.

[0042] exist Figure 2 The diagram shows a gas sensor 150 implemented as a nitrogen oxide sensor, comprising a first pumping chamber 251, a second pumping chamber 252, a reference oxygen chamber 253, a diffusion barrier 254, an electrode 255, a ceramic electrolyte 256, a heating element 257, and an electrical insulation portion 258.

[0043] At least one such electrochemical gas sensor 150 is configured to detect, as a measuring parameter, the partial pressure of carbon dioxide at the inlet and outlet of the absorption chamber of the device, the relationship between which represents a switching condition for controlling the air inlet, air outlet, and at least one delivery device in the case of an absorbent saturated with carbon dioxide. This switching condition is also referred to as a first switching condition for operating the device, in which the partial pressure of carbon dioxide at the air inlet is equal to or approximately equal to the partial pressure of carbon dioxide at the air outlet of the absorption chamber of the device, that is, p(CO2,in) = p(CO2,out).

[0044] Here, the first switching condition is accurately detected using a gas sensor (here, a NOx sensor and its dual pumping chamber system). In the first pumping chamber 251, readily present pure O2 molecules are pumped out of the measuring chamber by a correspondingly applied and adapted pump voltage and associated pump current I_O,Pump1. More difficult-to-separate CO2 molecules remain untouched and diffuse into the second measuring chamber, or pumping chamber 252. There, a higher pump voltage is applied at the pump electrode 255, thereby removing an O from the CO2. The measurable pump current I_O,Pump2 is a clearly relevant indicator of the proportion of CO2 present in the measured gas. Therefore, the relationship x_CO2 = f(I_O,Pump2) applies. In the context of use in the device, at least one NOx sensor, as a gas sensor 150, is placed at both the absorber inlet (air inlet) and the absorber outlet (air outlet) of the device. If both sensors measure the same CO2 value, then the absorbent has reached the point where it is saturated with CO2 and can no longer accept additional CO2.

[0045] NOx sensors are used in automotive technology to reduce nitrogen oxide emissions. The NOx sensor measures the oxygen and nitrogen oxide concentrations in exhaust gas, allowing for the corresponding addition of urea to reduce nitrogen oxide emissions, and enables the regeneration of the catalyst storing nitric oxide through a short, fuel-rich phase. Generally, the NOx sensor comprises a Nernst cell and two modified oxygen pump cells (oxygen pump cell, NOx cell). It consists of electrodes 255 and a ceramic solid electrolyte layer 256 that conducts oxygen ions. As an additional option, a heater element 257 is integrated into the sensor, which heats the sensor to a constant operating temperature between 500 and 800 °C.

[0046] In the oxygen pump single cell, the external pump electrode is located in the exhaust gas, and the internal pump electrode is located in the first cavity (first chamber 251). The cavity is separated from the exhaust gas by a diffusion barrier 254. As an alternative, a Nernst single cell is also present in the first cavity, which measures the Nernst voltage between the electrode 255 in the first cavity and the reference electrode 255 in a reference gas chamber or reference oxygen chamber 253 having a specified and known oxygen concentration. Both components operate on the same principle as a broadband oxygen detector.

[0047] In conjunction with the additional diffusion barrier 254, the improved oxygen pump single cell, as a NOx single cell, is located in the second hollow chamber or pumping chamber 252, wherein the electrode 255 is located in the second hollow chamber, and the paired electrode 255 is located in the reference gas chamber or reference oxygen chamber 253.

[0048] The internal pump electrode 255 of the first oxygen pump chamber in the first cavity, or first pumping chamber 251, is composed, for example, of platinum and gold, thus exhibiting lower activity compared to a broadband oxygen detector. This results in an applied pump voltage that is only sufficient to break down simple oxygen-containing molecules (e.g., NO2 → NO + O). The present NO passes through the electrode 255 virtually unchanged. However, in the second cavity, or second pumping chamber 252, a higher pump voltage is applied to the pump electrode 255, thereby completely breaking down NO at the pump electrode 255 and transporting away oxygen. Here, the pump electrode 255 also exhibits higher catalytic activity through, for example, a mixture of rhodium. Corresponding to NO, gaseous CO, or CO2, also represents molecules that are only difficult to break down, and therefore does not break down at the internal pump electrode 255 in the first cavity, or pumping chamber 251. The effect of unbroken CO, or CO2, at the pump electrode 255 is known from the use of a broadband oxygen detector in gases containing CO2.

[0049] The temporal trend of the load state during adsorption qualitatively presents the following situation: the load reaches saturation at some point. When saturation is achieved, the CO2 concentration at the inlet is equal to the CO2 concentration at the outlet. However, such a long wait is not necessary to avoid spending too much time for lower CO2 yields. When the absorbent is not yet at full load, the CO2 concentration at the outlet is lower than that at the inlet. To directly and quantitatively infer the load from this, it is possible to consider that the concentration difference depends, for example, on the volumetric flow rate at which air is transported through, and also on, for example, other environmental factors (such as temperature and air humidity). The relationship between the volumetric flow rate, the concentration difference, and the load state can be modeled.

[0050] Figure 3 Showing from Figure 1A schematic diagram of one embodiment of the gas sensor 150 of the device. The gas sensor 150 is implemented as a broadband oxygen detector, as is known, for example, from motor vehicle technology or in a similar manner. This type of gas sensor 150 can be used for at least one gas sensor in the device.

[0051] exist Figure 3 The diagram shows, by way of example only, a gas sensor 150 implemented as a broadband oxygen detector, including a first pumping chamber 251, a reference oxygen chamber 253, a diffusion barrier 254, an electrode 255, a ceramic electrolyte 256, a heating element 257, and an electrical insulation portion 258.

[0052] At least one such electrochemical gas sensor 150 is configured to detect, as a measurement parameter, the partial pressure of oxygen in an absorption chamber, relative to a predefined limit value, representing a switching condition for controlling at least one delivery device and a temperature control device in the case of a vacuum-sealed absorption chamber. This switching condition is also referred to as a second switching condition for operating the equipment, in which the partial pressure of oxygen is equal to or close to zero, or less than or equal to the predefined limit value, that is, p(O2) = 0 or p(O2) <= the limit value.

[0053] Whether a predefined limit has been reached during vacuuming (absolute vacuum is technically infeasible) can also be detected using a NOx sensor via the first pumping chamber 251. Correspondingly, this is equivalently feasible with a broadband oxygen detector, since the first pumping chamber 251 is precisely implemented in such a detector. Alternatively, this can also be determined by the jump in the Nernst voltage of a jump-type oxygen detector as the oxygen partial pressure decreases. Here, the relationships p(O2) = f(I_O,Pump1) or p(O2) = f(U_Nernst) apply.

[0054] An oxygen detector is used to measure the excess or deficiency of oxygen relative to the stoichiometric composition of a gas (especially combustion exhaust). The typical measurement range is λ = 0.65 … 1.3. For λ < 1, the following relationship applies to incompletely reformed, partially oxidized CHO gases or gas mixtures (whose molecules consist only of C, H, and oxygen atoms): λ = This is particularly applicable to broadband oxygen detectors, where an excess or deficiency of oxygen relative to the stoichiometric composition of a gas or combustion exhaust is measured based on a linear signal. In contrast, a jump-type oxygen detector has a jump-type signal response around λ = 1, thus making it particularly suitable for diagnosing transitions from oxygen-rich, lean gases to oxygen-poor, concentrated exhaust gases.

[0055] The broadband oxygen detector represents a combination of potentiometric and amperometric measurement methods. Here, a Nernst cell and a pump cell are connected in series, with a measurement gap, or chamber, for the measurement gas positioned between the two cell variants. A ceramic diffusion barrier 254 with defined known diffusion characteristics exists between the measurement chamber 251 and the exhaust gas. The detector is maintained at a constant temperature by means of a heating element 257, thereby eliminating the influence of temperature on the detector signal, or pump current. Furthermore, the broadband oxygen detector exhibits high signal dynamics with a response time of less than 100 ms. Due to the different oxygen partial pressures in the chamber and the surrounding ambient air (as a reference gas), the voltage signal of the Nernst cell should have a constant value of 450 mV, therefore λ = 1 in the measurement chamber 251. For this purpose, in motor vehicle applications, oxygen should be pumped into or out of the measurement chamber 251 according to the air-fuel mixture. The required pump current is proportional to the mass flow rate of oxygen. In the case of rich exhaust gas, oxygen is pumped from the exhaust gas electrode of the pump cell into the measurement chamber 251. For this purpose, oxygen is generated by the reduction of H2O and CO2 at the exhaust gas electrode 255, and then reacts with the diffused exhaust gas components via the electrolyte in the measuring chamber 251. The reaction products (H2O and CO2) diffuse outward through the diffusion barrier 254. In the case of lean exhaust gas or ambient air, oxygen is pumped from the inner pump electrode in the measuring chamber 251 of the pump unit to the outer pump electrode.

[0056] This jump-type detector, or two-point oxygen detector, represents a Nernst single-cell application scheme and is used in motor vehicle technology to regulate the stoichiometry of the air-fuel mixture in the sense of optimal exhaust gas treatment. It measures the applied Nernst voltage between the gas at gas electrode 255 and the known oxygen at reference electrode 255 in reference chamber 253.

[0057] Figure 4 Showing from Figure 1 A schematic diagram of one embodiment of the gas sensor 150 of the device. The gas sensor 150 is implemented as a broadband oxygen detector, as is known, for example, from motor vehicle technology or in a similar manner. This type of gas sensor 150 can be used for at least one gas sensor in the device.

[0058] exist Figure 4 The diagram shows, by way of example only, a gas sensor 150 implemented as a broadband oxygen detector, including a first pumping chamber 251, a reference oxygen chamber 253, a diffusion barrier 254, an electrode 255, a ceramic electrolyte 256, a heating element 257, and an electrical insulation portion 258.

[0059] At least one such electrochemical gas sensor 150 is configured to detect, as a measurement parameter, the partial pressure of oxygen and / or carbon dioxide at a carbon dioxide outlet, the relationship of which with respect to a predefined threshold represents a switching condition for controlling a temperature control device, at least one delivery device, an air inlet, an air outlet, and a carbon dioxide outlet upon termination of desorption. This switching condition is also referred to as a third switching condition for operating the equipment, in which the partial pressures of oxygen, carbon dioxide, and water are less than or equal to a predefined threshold, i.e., p(O2, CO2, H2O) <= threshold.

[0060] As in Figure 3 The equivalent behavior under the second switching condition also applies here. In the case of the previously mixed adsorption of CO2 and portions of O2 and H2O, it is essentially detected as the total oxygen equivalent. Ultimately, the oxygen detector detects the partial pressure of oxygen and does not distinguish the source of the detected oxygen atoms. The relationship p(O2) = f(I_O,Pump1) or p(O2) = f(U_Nernst) applies here. Alternatively, a jump-type oxygen detector can be used, employing the assessment as in lean exhaust gases.

[0061] To infer CO2 concentration, a NOx sensor specifically designed for CO2 is used based on this principle. Therefore, CO2 can be determined separately from H2O and oxygen in the air. Thus, it is possible to determine, during desorption, when CO2 is present in sufficient quantity.

[0062] Figure 5 A flowchart is shown as an embodiment of a method 500 for operating a device for separating carbon dioxide from ambient air. The method 500 can be implemented for operating devices from... Figure 1 The method 500 for operating the device or similar device includes a reading step 502 and a manipulation step 504.

[0063] Here, in the read-in step 502, a sensor signal is read from at least one electrochemical gas sensor. The sensor signal represents at least one oxygen-dependent measurement parameter detected in the absorption chamber by at least one electrochemical gas sensor. In the operation step 504, the air inlet, air outlet, carbon dioxide outlet, at least one delivery device, and / or temperature control device are operated according to the sensor signal read in the read-in step 502. Here, in the operation step 504, the air inlet and / or air outlet and / or carbon dioxide outlet and / or at least one delivery device and / or temperature control device are operated according to the current operating state of the equipment.

[0064] In one embodiment, a machine learning algorithm is used for the measurement parameters in step 502 of the detection process. This machine learning algorithm utilizes multiple linear regression, neural networks, and / or Gaussian processes. Furthermore, the algorithm is trained using training data to estimate the measurement error of at least one electrochemical gas sensor at different operating points of the device.

[0065] In other words, to improve the illustrated method 500 with the goal of higher accuracy (especially in CO2 determination and the correlation of measurement parameters for calorific value determination), the method 500 can be combined with a machine learning (ML) algorithm in the sense of a hybrid power system. Specifically, a machine learning algorithm can be used to estimate the error between the true value hs and the value hs,Sensor measured using the illustrated sensor design, and thus improve the last mentioned value hs,Sensor. For this purpose, it is only necessary to train the machine learning algorithm with training data during the preparation phase to estimate the error at different operating points. The machine learning algorithm can be set as a function of the gas sensor's measurement parameters (e.g., oxygen detector's measurement parameters, such as pump current, pump voltage, temperature, and Nernst voltage) and other parameters from the DAC system using the gas sensor (especially the oxygen detector) (e.g., temperature, pressure, volumetric flow rate, etc.). Thus, the sensor error represents the output parameter. Besides multiple linear regression, the use of neural networks and, in particular, the application of Gaussian processes are suitable approaches. The applicable relationship is... and .

[0066] Figure 6 A schematic diagram of a controller 600 according to one embodiment is shown. The controller 600 is configured to implement and / or control data from [unclear - possibly a specific source] in a corresponding unit. Figure 5 The steps of the method used for execution. Therefore, controller 600 is constructed for executing the steps from... Figure 1 The controller 600 is connected to or implemented as part of the device 100 or a similar device, or controls its operation. The controller 600 includes a reading device 602 and a control device 604.

[0067] The reading device 602 is configured to read in a sensor signal 601 from at least one electrochemical gas sensor 150. The sensor signal 601 represents at least one oxygen-dependent measurement parameter detected by the at least one electrochemical gas sensor 150 in the absorption chamber of the device 100. The control device 604 is configured to control an air inlet, an air outlet, a carbon dioxide outlet, at least one delivery device, and / or a temperature control device based on the sensor signal 601. For this purpose, the control device 604 is configured to generate a control signal 605 and output it to the air inlet, air outlet, carbon dioxide outlet, at least one delivery device, and / or temperature control device.

[0068] Figure 7 It shows the relationship with the source Figure 5 The flowchart of the operation process 700 combines the methods described above. Operation process 700 also relates to the general operating point of the DAC equipment, or the equipment from one of the previously described figures, or similar equipment. Operation process 700 can be implemented for operating the equipment from one of the previously described figures, or similar equipment.

[0069] In block 771 of operation process 700, the absorbent, or CO2 absorbent, is loaded with CO2 from the surrounding ambient air. When the absorbent is fully loaded (this is checked or verified in block 772), the loading process is stopped or continues. The following state can be used as an indicator: when the CO2 content or partial pressure of carbon dioxide at the inlet and outlet is equal or approximately equal. This is reflected by the first switching condition 770A, that is, p(CO2,in) = p(CO2,out). Before unloading, the absorption chamber is evacuated (see block 773) to remove the air present therein. The evacuation ends when oxygen (O2) is generally no longer present in the absorption chamber or when it falls below the technically relevant limit (this is checked or verified in block 774). This is reflected by the second switching condition 770B, that is, p(O2) = 0 or p(O2) <= the limit value. If the second switching condition 770B is met, the absorbent is heated in block 775 for desorption, and the desorbed CO2 is guided away in a controlled manner. The desorption process ends when CO2 is no longer present or detectable. This is the case when using steam desorption, as steam is continuously supplied to dilute the CO2. Without steam desorption, the flow rate weakens until all CO2 has been desorbed. Then, at, for example, 100 mbar (absolute value), the atmosphere consists only of CO2, with no flow rate. In block 776, the absorbent is queried or checked to see if it has been unloaded. Here, the third switching condition 770C is considered, that is, p(O2, CO2, H2O) <= threshold. In the case of previously mixed adsorption of CO2 and portions of O2 and H2O, these are also detected, but this has no negative impact on the method envisioned here. If the absorbent has been unloaded, the process 700 jumps back to block 771; otherwise, it continues to block 775 and then repeats block 776.

[0070] If an embodiment includes an "and / or" logical connection between a first feature and a second feature, it should be understood that the embodiment, in one implementation, has not only the first feature but also the second feature, and in another implementation, has either only the first feature or only the second feature.

Claims

1. An apparatus (100) for separating carbon dioxide (C) from ambient air (A), wherein, The device (100) has the following characteristics: An absorption chamber (110) for receiving absorbent (120) has a sealable air inlet (112) for allowing ambient air (A) to enter the absorption chamber (110), a sealable air outlet (114) for discharging outlet air (B) with reduced carbon dioxide from the absorption chamber (110), and a sealable carbon dioxide outlet (116) for discharging carbon dioxide (C) from the absorption chamber (110). At least one delivery device (130) is configured to deliver the ambient air (A) into the absorption chamber (110), deliver the outlet air (B) from the absorption chamber (110), evacuate the absorption chamber (110), and deliver carbon dioxide (C) from the absorption chamber (110). Temperature control device (140) configured to adjust the temperature of the absorbent (120) so as to cause carbon dioxide (C) absorbed at the absorbent (120) to desorb from the absorbent (120); as well as At least one electrochemical gas sensor (150) is configured to detect at least one oxygen-dependent measurement parameter in the absorption chamber (110).

2. The device (100) according to claim 1, wherein, The at least one electrochemical gas sensor (150) is configured to detect at least one oxide-dependent measurement parameter in the absorption chamber (110).

3. The device (100) according to any one of the preceding claims, wherein, The at least one electrochemical gas sensor (150) has a potentiometric and / or amperometric detection principle.

4. The device (100) according to any one of the preceding claims, wherein, The at least one electrochemical gas sensor (150) has an exhaust gas sensor and / or an exhaust gas sensor for motor vehicles and / or a nitrogen oxide sensor and / or an oxygen detector and / or a broadband oxygen detector and / or a jump-type oxygen detector.

5. The device (100) according to any one of the preceding claims, comprising a plurality of electrochemical gas sensors (150), wherein, At least one first gas sensor (150) is arranged in the region of the air inlet (112), and at least one second gas sensor (150) is arranged in the region of the air outlet (150).

6. The device (100) according to claim 5, wherein, At least one subset of the gas sensors (150) belong to the same sensor type, and / or at least one subset of the gas sensors (150) have different sensor types.

7. The device (100) according to any one of claims 5 to 6, wherein, At least one of the electrochemical gas sensors (150) is a nitrogen oxide sensor.

8. The device (100) according to any one of the preceding claims, wherein, The at least one electrochemical gas sensor (150) is configured to detect, as a measurement parameter, the partial pressure of carbon dioxide at the air inlet (112) and the partial pressure of carbon dioxide at the air outlet (114), the relationship between them representing the switching conditions (770A) for controlling the air inlet (112), the air outlet (114) and the at least one delivery device (130) in the case of an absorbent (120) saturated with carbon dioxide.

9. The device (100) according to any one of the preceding claims, wherein, The at least one electrochemical gas sensor (150) is configured to detect the partial pressure of oxygen in the absorption chamber (110) as a measurement parameter, the relationship of which with respect to a predefined limit value represents the switching conditions (770B) for controlling the at least one delivery device (130) and the temperature control device (140) in the case of a vacuumed absorption chamber (110).

10. The device (100) according to any one of the preceding claims, wherein, The at least one electrochemical gas sensor (150) is configured to detect, as a measurement parameter, the partial pressure of oxygen and / or the partial pressure of carbon dioxide at the carbon dioxide outlet (116), the relationship of which with respect to a predefined threshold represents the switching conditions (770C) for controlling the temperature control device (140), the at least one delivery device (130), the air inlet (112), the air outlet (114) and the carbon dioxide outlet (116) upon termination of desorption.

11. The device (100) according to any one of the preceding claims, wherein, The absorbent (120) is disposed in the absorption chamber (110) between the air inlet (112) and the air outlet (114), wherein the absorbent (120) is configured to cause reversible adsorption of carbon dioxide (C) from the ambient air (A) at the absorbent (120).

12. A method (500) for operating the device (100) according to any one of the preceding claims, wherein, The method (500) comprises the following steps: Read (502) the sensor signal (601) of the at least one electrochemical gas sensor (150), wherein the sensor signal (601) represents at least one oxygen-dependent measurement parameter detected by the at least one electrochemical gas sensor (150) in the absorption chamber (110); and Based on the sensor signal (601) read in the reading step (502), operate (504) the air inlet (112) and / or the air outlet (114) and / or the carbon dioxide outlet (116) and / or the at least one delivery device (130) and / or the temperature control device (140).

13. The method (500) according to claim 12, wherein, In the detection step (502), a machine learning algorithm is used for the measurement parameters, in which multiple linear regression, neural networks and / or Gaussian processes are used, wherein the algorithm is trained with training data to estimate the measurement error of the at least one electrochemical gas sensor at different operating points of the device (100).

14. A controller (600) configured to implement and / or manipulate the steps (502, 504) of the method (500) according to any one of claims 12 or 13 in corresponding units (602, 604).

15. A computer program configured to implement and / or manipulate steps (502, 504) of the method (500) according to any one of claims 12 or 13.

16. A machine-readable storage medium having a computer program as claimed in claim 15 stored thereon.

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