A carbon dioxide catcher, a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher and a computer program

Abstract

The disclosure relates to a carbon dioxide catcher (100) comprising: two reactors (110a, 110b), each reactor comprising at least one cassette (120a, 120b) with a carbon capture material; and a process air circuit (S1) configured to conduct process through each reactor (110a, 110b), wherein the carbon dioxide catcher (100) further comprises a pair of valves (150a, 150b) configured to conduct process air through one reactor (110a, 110b) at a time, wherein the carbon dioxide catcher (100) further comprises a control unit (160) configured to control the valves (150a, 150b) such that the process air is switched from being conducted through one of the reactors (110a, 110b) to the other based on a carbon dioxide level in the process air downstream of the reactors (110a, 110b). The disclosure further relates to a method (200) for removing carbon dioxide from process air conducted through a carbon dioxide catcher (100) and a computer program.

Description

The present disclosure relates to a carbon dioxide catcher, a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher and a computer program. More specifically, the disclosure relates to a carbon dioxide catcher, a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher and a computer program as defined in the introductory parts of the independent claims.Background artCarbon dioxide (CO2) is a major greenhouse gas contributing to global warming and climate change and various ways of capturing the gas have been developed over the years. By capturing the carbon dioxide for example from industrial sources helps reducing the amount of this gas released to into the atmosphere, mitigating its impact on the environment.Different types of carbon dioxide capture material are known, for example covalent organic frameworks, metal-organic frameworks, activated carbon, zeolites and carbon nanotubes. Carbon dioxide capture materials are also good at adsorbing water vapor, which can compete with the capturing of carbon dioxide. Carbon dioxide catchers typically comprises one or more reactors with cassettes containing the carbon dioxide capture material.SummaryThere is a need in the art to improve utilization of the one or more reactors.It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem.According to a first aspect there is provided a carbon dioxide catcher comprising: two reactors, each reactor comprising at least one cassette with a carbon capture material; and a process air circuit configured to conduct process through each reactor, wherein the carbon dioxide catcher further comprises at least one valve configured to allow process air to be conducted through one reactor at a time, wherein the carbon dioxide catcher further comprises a control unit configured to control the at least one valve such that the process air is switched from being conducted through one of the reactors to the other based on a carbon dioxide level in the process air downstream of the reactors.The reactor may also be referred to as an adsorbent and / or absorbent unit. Thus, the reactor is a unit configured to adsorb and / or absorb carbon dioxide in process air conducted through the reactor.The disclosed carbon dioxide catcher can thereby operate uninterrupted when one of the reactors gets saturated. By performing the switch based on the carbon dioxide level, energy efficiency is improved by allowing the carbon dioxide catcher reactor to adsorb energy for longer durations compared to a switching scheme based on fixed durations of carbon dioxide capture; unnecessary regeneration cycles can thereby be avoided and energy can be saved.According to some examples, the disclosed carbon dioxide catcher further comprises a regeneration air circuit configured to conduct regeneration air through the reactors, wherein the control unit further is configured to initiate a regeneration process during the switch of process air, such that regeneration air is conducted through the reactor that is no longer receiving process air, the regeneration air being configured to release adsorbed carbon dioxide from the carbon capture material of the at least one cassette.According to an example, the regeneration process is performed for a predetermined duration. The time it takes to remove adsorbed carbon dioxide during normal operating conditions are typically known and can be used to minimize the time it takes to transition from using one reactor to using the other.According to some examples, the control unit is further configured to initiate a second regeneration process prior to the switch of process air, wherein the second regeneration process is configured to conduct regeneration air via a regeneration air circuit through the reactor that is being switched to, the second regeneration process being performed prior to the switch. The reactor being switched to is thereby being prepared to function optimally when process air is conducted through it. The second regeneration process can be performed for a predetermined duration or be terminated based on a criterion indicating that no further carbon dioxide is being desorbed from the carbon dioxide capture material. In other words, in some examples, the second regeneration process is performed for a predetermined duration. In some other examples, the second regeneration process is performed until a carbon dioxide level of the regeneration air downstream remains stable for a predetermined duration.By removing adsorbed carbon dioxide, the regeneration processes prepare the reactor for use once more and ensures that the cycle of switching between reactors can be performed automatically, that is without the need for manual labour.According to some examples, the carbon dioxide catcher comprises a sensor configured to measure the carbon dioxide level in the process air downstream of the reactors.According to a second aspect there is provided a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher according to the first aspect, the method comprising: controlling the valves such that the process air is switched from being conducted through one of the reactors to the other based on a carbon dioxide level in the process air downstream of the reactors.In some examples, the method further comprises obtaining measurement data relating to the carbon dioxide level in the process air downstream of the reactors.In some examples, the method also comprises initiating a regeneration process during the switch of process air, so that regeneration air is conducted through the reactor that is no longer receiving process air, the regeneration air being configured to release adsorbed carbon dioxide from the carbon capture material of the at least one cassette.According to a third aspect there is provided a computer program comprising computer program code which, when executed by a processor of the control unit of a carbon dioxide catcher according to any of the first aspect, causes the carbon dioxide catcher to execute the method according to the second aspect.According to a fourth aspect there is provided to a computer program product for a carbon dioxide catcher according to the first aspect, the computer program product comprising a non-transitory computer-readable storage medium having thereon a computer program comprising program instructions, the computer program being loadable into a processor and configured to cause the processor to perform the method according to the second aspect.Effects and features of the second, third and fourth aspects are to a large extent analogous to those described above in connection with the first aspect. Examples mentioned in relation to the first aspect are largely compatible with the second, third and fourth aspects.The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred examples of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular examples only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.Brief descriptions of the drawingsThe above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.Figures la and lb show a carbon dioxide catcher according to an example of the present disclosure; andFigure 2 shows a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher.Detailed descriptionThe present disclosure will now be described with reference to the accompanying drawings, in which preferred examples of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed examples. The disclosed examples are provided to fully convey the scope of the disclosure to the skilled person.Figures la and lb show a carbon dioxide catcher according to an example of the present disclosure. Specifically, the schematic illustrations show air being conducted through one reactor 110b in Fig. la and then the other reactor 110a in Fig. lb.The first aspect of this disclosure shows a carbon dioxide catcher 100 comprising: two reactors 110a, 110b, each reactor comprising at least one cassette 120a, 120b with a carbon capture material; and a process air circuit SI configured to conduct process through each reactor 110a, 110b, wherein the carbon dioxide catcher 100 further comprises at least one valve 150a, 150b configured to allow process air to be conducted through one reactor 110a, 110b at a time, wherein the carbon dioxide catcher 100 further comprises a control unit 160 configured to control the at least one valve 150a, 150b such that the process air is switched from being conducted through one of the reactors 110a, 110b to the other based on a carbon dioxide level in the process air downstream of the reactors 110a, 110b.The carbon dioxide catcher 100 thereby optimizes the usage of one of the reactors before switching to using the other, thereby reducing or eliminating unnecessary switches and associated regeneration steps, thereby saving energy.According to some examples, the carbon comprises a sensor 170 configured to measure the carbon dioxide level in the process air downstream of the reactors 110a, 110b.In an operational use context, there is typically a start-up stage and a stage where the carbon dioxide catcher 100 is up and running. In practice the process air coming in to the carbon dioxide catcher 100 needs to be dehumidified for the carbon dioxide capture material to be able to adsorb carbon dioxide effectively. In some of these examples, the carbon dioxide catcher 100 receives process air from an upstream dehumidifier during the start-up stage, wherein the process air is guided through the carbon dioxide catcher 100, for instance via a dedicated air circuit, until a predetermined humidity level has been reached. In other words, in some examples the carbon dioxide catcher 100 is configured to let process air bypass the carbon dioxide catcher 100 until the predetermined humidity level has been achieved in the process air downstream of the dehumidifier. This means that the dehumidifier has now dehumidified the process air to the point where humidity will not interfere with the carbon dioxide adsorption process.In a next step of the start-up stage, the reactors of the carbon dioxide catcher 100 are prepared for carbon dioxide capture. The preparation includes removing carbon dioxide that is currently adsorbed and making sure that the reactors are at an optimal temperature for carbon dioxide adsorption.For clarity, the two reactors will 110a, 110b will also be referred to as the first and second reactor.Thus, according to some examples, the carbon dioxide catcher 100 is configured to start a regeneration process that conducts dehumidified process air through the first reactor 110a. After the regeneration process of the first reactor 110a is complete, the temperature of the first reactor is cooled to a predetermined temperature. Thus, in some examples, the carbon dioxide catcher 100 is further configured to cool the first reactor 110a to a predetermined temperature. This process of regeneration and cooling is then repeated for the other reactor. The air used for regeneration is preferably heated by a heat exchanger and / or a heater of the carbon dioxide catcher. Thus, in some examples, the carbon dioxide catcher 100 comprises a heat exchanger and / or a heater configured to heat regeneration air conducted through each reactor 110a, 110b.When both reactors have been regenerated and cooled, a final step in the start-up stage is to conduct the dehumidified process air through both reactors 110a, 110b in a purging step. Thus, according to some examples, the carbon dioxide catcher 100 is configured to conduct dehumidified process air through both reactors 110a, 110b.In some further examples, each regeneration process is performed for a predetermined duration. In some examples, each regeneration process is performed until the carbon dioxide level of the regenerated air is at or below a predetermined level.In summary, according to some examples the carbon dioxide catcher 100 is configured to: conduct process air through the carbon dioxide catcher 100 until the process air downstream of the carbon dioxide catcher has reached a predetermined humidity level; conducting regeneration air through each reactor 110a, 110b; cool each reactor 110a, 110b to a predetermined temperature; and conducting purge air through each reactor 110a, 110b.With the start-up stage complete, the carbon dioxide catcher 100 can start the carbon dioxide adsorption at one of the reactors. This is illustrated in Figure la as process air being conducted through the first reactor 110a. When the process air is switched from being conducted through one of the reactors, here illustrated as the first reactor 110a, to the other, as illustrated in Figure lb, the carbon dioxide catcher preferably also initiates a regeneration process for the reactor no longer being used to adsorb carbon dioxide.Thus, according to some examples, the control unit 160 further is configured to initiate a regeneration process during the switch of process air, wherein the regeneration process is configured to conduct regeneration air via a regeneration air circuit S2a,S2b through the reactor 110a, 110b that is no longer conducting process air, the regeneration air being configured to release adsorbed carbon dioxide from the carbon capture material of the at least one cassette 120a, 120b. In some examples, the regeneration process is performed for a predetermined duration. In some further examples, the regeneration process is followed by a cooling of the reactor in order to prepare it for carbon dioxide adsorption. Thus, in some examples, the control unit 160 further is configured to initiate a cooling process configured to cool the regenerated reactor.In other words, in some examples the carbon dioxide catcher 100 further comprises a regeneration air circuit S2a, S2b configured to conduct regeneration air through the reactors 110a, 110b, wherein the control unit 160 further is configured to initiate a regeneration process during the switch of process air, such that regeneration air is conducted through the reactor 110a, 110b that is no longer receiving process air, the regeneration air being configured to release adsorbed carbon dioxide from the carbon capture material of the at least one cassette 120a, 120b. According to some further examples, the regeneration process is performed for a predetermined duration.In some examples, the carbon dioxide catcher 100 is configured to conduct process air through both reactors 110a, 110b simultaneously during the switch. In some further examples, the simultaneous conducting of process air is performed for a predetermined duration.According to some examples, the control unit is further configured to initiate a second regeneration process prior to the switch of process air, wherein the second regeneration process is configured to conduct regeneration air via a regeneration air circuit through the reactor that is being switched to, the second regeneration process being performed prior to the switch.Figure 2 shows a method for removing carbon dioxide from process air conducted through a carbon dioxide catcher 100. The carbon dioxide catcher 100 is configured as disclosed in Figure la-b.The method 200 comprises: controlling S200 the valves 150a, 150b such that the process air is switched from being conducted through one of the reactors 110a, 110b to the other based on a carbon dioxide level in the process air downstream of the reactors 110a, 110b.The method 200 performs the functions of the disclosed carbon dioxide catcher 100 and has all the same technical effects and advantages.According to some examples, the method comprises: obtaining 5100 measurement data relating to the carbon dioxide level in the process air downstream of the reactors 110a, 110b.According to some examples, controlling 5200 the valves further comprises initiating 5210 a regeneration process during the switch of process air, so that regeneration air is conducted through the reactor 110a, 110b that is no longer receiving process air, the regeneration air being configured to release adsorbed carbon dioxide from the carbon capture material of the at least one cassette 120a, 120b.The method 200 may further comprise any steps for which the carbon dioxide catcher 100 according to any example of the first aspect is configured.The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims.Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. Carbon dioxide separators (lOO) including:- two reactors (110a, 110b), where each reactor comprises at least one cassette (120a, 120b) with a material for carbon dioxide separation, and- a process air circuit (SI), configured to lead process air through each reactor (110a, 110b),wherein the carbon dioxide separator (100) further comprises at least one valve (150a, 150b) configured to allow process air to be passed through one reactor (110a, 110b) at a time, and further comprises a control unit (160) configured to control at least one valve (150a, 150b), characterized in that the process air is switched from being passed through the one reactor (110a, 110b) to the other based on the carbon dioxide level in the process air downstream of the reactors (110a, 110b).

2. Carbon dioxide separator (100) according to patent claim 1, further comprising a regeneration air circuit (S2a, S2b) configured to lead regeneration air through the reactors (110a, 110b), whereby the control unit (160) is further configured to initiate a regeneration process during the exchange of process air, so that regeneration air is led through the reactor (110a, 110b) which no longer receives process air, whereby the regeneration air is configured to release adsorbed carbon dioxide from the material for carbon dioxide separation in at least one cassette (120a, 120b).

3. Carbon dioxide separator (100) according to patent claim 2, wherein the regeneration process is carried out for a predetermined time period / duration.

4. Carbon dioxide separator (100) according to some of the preceding patent claims, further including:- a sensor (170) configured to measure the carbon dioxide content in the process air downstream of the reactors (110a, 110b).

5. Method (200) for removing carbon dioxide from process air which is passed through a carbon dioxide separator (100) according to one of patent claims 1-4, characterized by controlling (S200) the valves (150a, 150b) so that the process air is switched from being passed through one of the reactors (110a, 110b) to the other based on the carbon dioxide level in the process air downstream of the reactors (110a, 110b).

6. Process (200) enligt patent claim 5, further comprising:- to obtain (S100) measured data related to the carbon dioxide level in the process air downstream of the reactors (110a, 110b).

7. Method (200) according to patent claim 5 or 6, where the control (S200) of the valves further includes:- to initiate (S210) a regeneration process during the exchange of process air, so that regeneration air is led through the reactor (110a, 110b) which no longer receives process air, whereby the regeneration air is configured to release adsorbed carbon dioxide from the carbon dioxide separation material in at least one cassette (120a, 120b).

8. Computer program which includes computer program code which, when executed by a processor (162) in the control unit (160) in a carbon dioxide separator (100) according to one of the patent claims 1-4, causes the carbon dioxide separator (100) to perform the procedure according to one of the patent claims 5-7.