KR20200085633A - High purity methane production system and high purity methane production method using same - Google Patents

Abstract

An absorption liquid inlet for receiving an absorption liquid in which carbon dioxide is dissolved, a reducing metal for reducing hydrogen ions contained in the absorption liquid to hydrogen molecules, and a methanation reaction tank provided with the reduced hydrogen molecules and a methane producing bacteria producing carbon dioxide as methane, and A high-purity methane production system is provided, having a methane generating unit comprising a methane outlet that discharges the produced methane.

Description

High purity methane production system and high purity methane production method using same}

The present invention relates to a high-purity methane production system and a high-purity methane production method using the same, and more particularly, to a system for producing high-purity methane from biogas by a reducing metal and methane-producing bacteria and a high-purity methane production method using the same.

As awareness of environmental issues increases, issues related to carbon dioxide reduction and treatment are drawing attention worldwide.

Conventionally, in order to remove carbon dioxide, a method of capturing carbon dioxide, a method of adsorbing, or a method of separating using a separator is used.

For example, in the Republic of Korea Patent Publication KR20130046626A, using a porous membrane, as a method of separating methane from CBM (Cold Bed Methane) having a methane and carbon dioxide content of 88 to 92% by weight and 8 to 12% by weight, respectively, the above A method for separating methane with a pressure difference of 5 to 7 MPa between the front and rear surfaces of a porous membrane is disclosed.

However, conventional technologies for treating carbon dioxide are focused on a method of separating and recovering carbon dioxide. Therefore, an additional process for reprocessing the separated and recovered carbon dioxide is required. Therefore, the process is not only complicated, but also incurs additional processing costs, which is inefficient.

Accordingly, there is a need for a method capable of removing carbon dioxide, which is a cause of environmental problems, and simultaneously regenerating energy resources, that is, natural gas.

One technical problem to be solved by the present invention is to provide a high-purity methane production system that simultaneously removes carbon dioxide and produces high-purity methane.

Another technical problem to be solved by the present invention is to provide a high-purity methane production system in which a reducing metal that reduces hydrogen ions present in water to hydrogen molecules is provided.

Another technical problem to be solved by the present invention is to provide a high-purity methane production system in which methane-producing bacteria that produce reduced hydrogen molecules and carbon dioxide dissolved in water as methane are provided.

Another technical problem to be solved by the present invention is to provide a high-purity methane production system that provides a carrier with a reducing metal attached to the surface.

Another technical problem to be solved by the present invention is to provide a high-purity methane production system that provides a carrier separating the reducing metal and methane producing bacteria.

Another technical problem to be solved by the present invention is to provide a high-purity methane production method for producing a methane content of at least 93%.

Another technical problem to be solved by the present invention is to provide a high-purity methane production method for producing carbon dioxide dissolved in water as methane.

Another technical problem to be solved by the present invention is to provide a high-purity methane production method for returning an absorbent solution in which carbon dioxide is dissolved in water before being reduced to methane.

Another technical problem to be solved by the present invention is a high purity in which the steps of producing carbon dioxide absorbed and dissolved in water by reduction with methane, and the step of returning the absorbent liquid in which carbon dioxide not reduced by methane is dissolved are repeatedly performed. It is to provide a method for producing methane.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problem, a high-purity methane production system is provided.

According to one embodiment, the high-purity methane production system, the absorption liquid inlet for receiving the absorption liquid dissolved carbon dioxide, a reducing metal for reducing hydrogen ions contained in the absorption liquid to hydrogen molecules and the reduced hydrogen molecules and the carbon dioxide methane It may have a methane generation unit including a methanation reaction tank provided with a methane producing bacteria produced by, and a methane outlet to discharge the produced methane.

According to one embodiment, the high-purity methane production system, a gas inlet through which biogas containing carbon dioxide and methane flows, a carbon dioxide absorption tank for dissolving the carbon dioxide in an absorbent liquid, a methane outlet for discharging the methane, and the methane production It may have a carbon dioxide dissolving portion that is in communication with a negative absorption liquid inlet, and includes an absorption liquid outlet that provides an absorption liquid in which carbon dioxide in the carbon dioxide absorption tank is dissolved.

According to an embodiment, the methane generation unit may further include an absorption liquid return port for transporting carbon dioxide not generated as methane in the methanation reaction tank to the carbon dioxide dissolving unit.

According to an embodiment of the present disclosure, a biogas providing unit that provides biogas by communicating with the gas inlet of the carbon dioxide dissolving unit may be further included.

According to an embodiment, the methane outlet of the methane generating unit and the methane outlet of the carbon dioxide dissolving unit are in communication, and may further include a methane storage unit through which the methane is introduced.

According to an embodiment, the reducing metal further includes a carrier attached to the surface, and the reducing metal and the methane producing bacteria may be spaced apart from each other by the carrier.

According to an embodiment, the carrier may reduce the hydrogen ions to hydrogen molecules.

According to one embodiment, the size of the carrier may be 75 ~ 425 μm.

According to an embodiment, the main component of the reducing metal may be zero iron.

In order to solve the above technical problem, a method for producing high-purity methane is provided.

According to one embodiment, the high-purity methane production method, the step of introducing an absorption liquid in which carbon dioxide is dissolved, reducing hydrogen ions contained in the absorption liquid into hydrogen molecules by a reducing metal, the reduced hydrogen molecules and the carbon dioxide It may include the step of producing as methane by methane producing bacteria, and the step of flowing out the produced methane.

According to an embodiment, prior to the step of introducing the absorbent liquid, a step of introducing biogas containing carbon dioxide and methane, and dissolving the carbon dioxide in the absorbent liquid may be further included.

According to one embodiment, in the step of dissolving the carbon dioxide in the absorbent liquid, it may further include discharging methane contained in the biogas.

According to one embodiment, the reducing metal may further include the step of preparing a carrier attached.

According to one embodiment, the step of preparing the carrier to which the reducing metal is attached, adding a reducing metal in a solvent to prepare a reducing metal ion solution, mixing the carrier with the reducing metal ion solution, and mixing solution It may include the step of manufacturing, and adding a reducing agent to the mixed solution, the step of attaching the reducing metal ion to the carrier.

According to an embodiment of the present invention, methane in the biogas is first collected, carbon dioxide in the biogas is dissolved in an absorbent solution, and produced by methane, a reducing metal and a methane-producing bacteria, second-generation high-purity methane production system, and A method for producing high purity methane is provided.

Accordingly, high-purity methane can be produced while removing carbon dioxide.

1 is a view for explaining a high-purity methane production system according to an embodiment of the present invention.
2 is a view for explaining a carbon dioxide melting unit according to an embodiment of the present invention.
3 and 4 are views for explaining a methane generating unit according to an embodiment of the present invention.
5 is a flowchart illustrating a method for producing high-purity methane according to an embodiment of the present invention.
6 is a flowchart for explaining step S140.
7 is a photograph of a carrier according to Experimental Examples 1-1 and 2-1 of the present invention.
8 is a photograph of a carrier in which a reducing metal according to Experimental Examples 1-2 and 2-2 of the present invention is attached to a surface.
9 is a view showing a comparison of the hydrogen generation amount of the carriers according to Experimental Examples 1-1 and 2-1 of the present invention.
10 is a view showing the hydrogen generation characteristics of each carrier attached to the surface of the reducing metal according to Experimental Examples 1-2 and 2-2 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete and that the spirit of the present invention is sufficiently conveyed to those skilled in the art.

In the present specification, when a component is referred to as being on another component, it means that it may be formed directly on another component, or a third component may be placed between them. In addition, in the drawings, the shape and the thickness of the regions are exaggerated for effective description of the technical content.

Further, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another component. Therefore, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. Also, in this specification,'and/or' is used to mean including at least one of the components listed before and after.

In the specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. Also, terms such as “include” or “have” are intended to indicate the existence of features, numbers, steps, elements or combinations thereof described in the specification, and one or more other features, numbers, steps, or configurations. It should not be understood as excluding the possibility or presence of elements or combinations thereof. In addition, in this specification, "connecting" is used in a sense to include both indirectly connecting a plurality of components, and directly connecting.

In addition, terms such as “…unit”, “…group”, and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

In addition, in the following description of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

As awareness of environmental issues increases, issues related to carbon dioxide reduction and treatment are drawing attention worldwide.

If carbon dioxide, which is a cause of environmental problems, is not only removed, but also used as an energy resource, the benefits can be achieved.

Accordingly, the present invention aims to remove carbon dioxide and to regenerate it as an energy resource, that is, natural gas.

In order to achieve the above goal, a natural gas according to an embodiment of the present invention, specifically, a high-purity methane production system is described.

1 is a view for explaining a high-purity methane production system according to an embodiment of the present invention, FIG. 2 is a view for explaining a carbon dioxide melting unit according to an embodiment of the present invention, and FIGS. 3 and 4 are embodiments of the present invention It is a view for explaining the methane generating unit according to.

Referring to Figure 1, the high-purity methane production system 1000 according to an embodiment of the present invention, a methane generating unit 100, a carbon dioxide dissolving unit 200, a biogas providing unit 300, a methane storage unit 400 , And a regeneration tank 500. Hereinafter, each configuration will be described in detail.

As illustrated in FIG. 1, the biogas providing unit 300 may provide biogas (BG) to the carbon dioxide dissolving unit 200.

Specifically, the biogas providing unit 300 may include a biogas outlet. Accordingly, the biogas provider 300 may provide biogas (BG) to the carbon dioxide dissolving unit 200 through the biogas outlet.

Here, the biogas (BG) may include carbon dioxide (CO ₂ ) and methane (CH ₄ ). Specifically, the biogas (BG) may include 40-50% carbon dioxide and 50-60% methane.

In order to achieve the object of the present invention described above, in order to use biogas (BG) as an energy resource, that is, natural gas, to produce carbon dioxide in the biogas (BG) as methane, the content of methane is 93% It should be ideal.

Conventional biogas (BG) regeneration treatment uses a method of separating carbon dioxide from biogas (BG) to relatively increase the methane content in the biogas (BG).

However, an additional process for treating the separated carbon dioxide is required. Therefore, the process is not only complicated, but also incurs additional processing costs, which is inefficient.

However, according to an embodiment of the present invention, carbon dioxide in biogas (BG) may be produced as methane. That is, unlike the conventional method, by separating carbon dioxide from the biogas (BG), rather than increasing the relative content of methane, by regenerating carbon dioxide in the biogas (BG) as methane, the biogas (BG) In addition to the existing methane content, it is to increase the total methane content.

Therefore, according to an embodiment of the present invention, an additional process for treating the separated carbon dioxide is unnecessary and efficient.

In addition, carbon dioxide in the introduced biogas (BG) is converted to methane and produced, and discharged together with the existing methane in the biogas (BG), so that the methane emission compared to the inflow of biogas (BG), that is, methane productivity Can be improved.

2, the carbon dioxide dissolving unit 200 may include a gas inlet 110, a carbon dioxide absorption tank 120, a methane outlet 130, and an absorbent liquid outlet 140. Hereinafter, each configuration will be described.

The gas inlet 110 of the carbon dioxide melting unit 200 may be a passage through which biogas (BG) including the carbon dioxide and methane is introduced. That is, the gas inlet 110 may be in communication with the biogas outlet of the biogas providing unit 300 described above. Accordingly, the gas inlet 110 is to allow the biogas (BG) leaked from the biogas providing unit 300 to flow into the carbon dioxide dissolving unit 200.

The carbon dioxide absorption tank 120 may include an absorption liquid 142. Accordingly, the carbon dioxide absorption tank 120 may dissolve carbon dioxide in the introduced biogas (BG) in the absorption liquid 142.

In the same condition, the solubility of carbon dioxide may be greater than that of methane. Specifically, the solubility of carbon dioxide may be about 10 times greater than that of methane.

Accordingly, carbon dioxide in the biogas (BG) introduced into the carbon dioxide absorption tank 120 may be dissolved in the absorption liquid 142.

Meanwhile, methane in the biogas (BG) introduced into the carbon dioxide absorption tank 120 may be present in a gas phase without being dissolved in the absorption liquid 142.

According to the object of the present invention, in order to produce high-purity methane from biogas (BG), carbon dioxide in the biogas (BG) is dissolved in the absorption liquid 142 of the carbon dioxide absorption tank 120, and the absorption liquid 142 Undissolved methane can be discharged and stored as an energy resource.

To this end, the methane outlet 130 may discharge methane that is not dissolved in the absorbent liquid 142.

The methane discharged through the methane outlet 130 may be stored in the methane storage 400 as shown in FIG. 1.

The absorption liquid outlet 140 may communicate the carbon dioxide dissolving portion 200 and the methane generating portion 100. Accordingly, the absorption liquid 142 in which the carbon dioxide of the carbon dioxide dissolving portion 200 is dissolved may be introduced into the methane generating portion 100 by the absorption liquid outlet 140.

That is, according to an embodiment of the present invention, in the carbon dioxide dissolving unit 200, carbon dioxide in the biogas (BG) introduced from the biogas providing unit 300 is dissolved in the absorbent liquid 142 to generate the methane. It can be introduced into the (100), the methane of the biogas (BG) can be discharged and stored in the methane storage 400.

Accordingly, the high-purity methane production system 1000, according to the object of the present invention, is to collect and primarily store methane from biogas (BG).

Referring to FIG. 3, the methane generating unit 100 may include an absorbent liquid inlet 10, a methanation reaction tank 20, a methane outlet 30, and an absorbent liquid carrier 40. Hereinafter, each configuration will be described.

The absorption liquid inlet 10 of the methane generating unit 100 may be a passage through which the absorption liquid 142 in which the carbon dioxide is dissolved flows. That is, the absorbent liquid inlet 10 may be in communication with the absorbent liquid outlet 140 of the carbon dioxide dissolving unit 200 described above. Accordingly, the absorbent liquid inlet 10 is to allow the absorbent liquid 142 flowing out of the carbon dioxide dissolving unit 200 to flow into the methane generating unit 100.

The methanation reaction tank 20 may generate carbon dioxide of the absorbent liquid 142 introduced through the absorbent liquid inlet 10 as methane. To this end, the methanation reaction tank 20 may include a reducing metal (RM) and a methane producing bacteria (MB).

Specifically, the methanation reaction tank 20 may reduce hydrogen ions (H ⁺ ) contained in the absorption liquid 142 to hydrogen molecules (H ₂ ) by the reductive metal (RM). Thereafter, the methanation reaction tank 20 is capable of producing methane by combining the reduced hydrogen molecules with carbon molecules of carbon dioxide dissolved in the absorbent solution 142 by the methane-producing bacteria (MB).

According to one embodiment, the main component of the reducing metal (RM) may be zerovalent iron (ZVI; zerovalent iron, Fe ^O ). For example, the main component of the reducible metal (RM) may be iron or iron, obtained from scrap iron generated as waste in the steelmaking process. Alternatively, the main component of the reducible metal (RM) may be nano zerovalent iron (nZVI) obtained by synthesis.

According to one embodiment, the methane-producing bacteria (MB) may be anaerobic microorganisms. Accordingly, carbon dioxide can be produced as methane even in an oxygen-free environment.

The methane outlet 30 may discharge the produced methane. To this end, the methane outlet 30 may be in communication with the methane storage 400. Accordingly, as illustrated in FIG. 1, methane discharged through the methane outlet 30 may be stored in the methane storage 400.

As described above, according to the object of the present invention, in order to produce high-purity methane from biogas (BG), in the carbon dioxide dissolving unit 200, biogas introduced from the biogas providing unit 300 (BG ) Of methane can be discharged to the methane storage 400 to be stored first.

Thereafter, carbon dioxide in the biogas (BG) introduced from the biogas providing unit 300 may be dissolved in the absorbent liquid 142 and introduced into the methane generating unit 100. In the methane generating unit 100, carbon dioxide of the introduced absorbent liquid 142 may be produced as methane, and discharged to the methane storage unit 400 for storage.

Accordingly, the high-purity methane production system 1000, according to the object of the present invention, is to produce and store secondary methane from biogas (BG).

On the other hand, the methane generation unit 100, the methanation reaction tank 20, the carbon dioxide that is not produced as methane in the absorbent 142, may be returned to the carbon dioxide dissolving unit 200.

To this end, the methane generating unit 100 may include an absorbent liquid transport port 40 that transports carbon dioxide not produced by the methane to the carbon dioxide dissolving unit 200.

The absorbent liquid transport port 40 may be in communication with the gas inlet port 110 of the carbon dioxide dissolving unit 200. Accordingly, the absorption liquid 142 in which carbon dioxide not produced by the methane is dissolved in the methane generating unit 100 can be returned to the carbon dioxide melting unit 200.

The absorbent liquid 142 returned to the carbon dioxide dissolving unit 200 may be introduced into the methane generating unit 100 again. Accordingly, the carbon dioxide of the absorption liquid 142 not produced by the methane in the methane generating unit 100 can reproduce methane.

That is, according to an embodiment of the present invention, a cyclic process of producing carbon dioxide dissolved in the absorbent liquid 142 as methane, and conveying the absorbent liquid 142 dissolved in carbon dioxide not produced as methane may be repeatedly performed. have.

Therefore, the high-purity methane production system 1000 is capable of producing high-purity methane according to the object of the present invention. Here, high-purity methane means methane having a content of 93% or more.

In order to produce the high-purity methane, according to one embodiment, the high-purity methane production system 1000, the absorption liquid transfer port 40, and the carbon dioxide gas inlet port 110 to include a mixing device Can.

The mixing device, a new biogas (BG) flowing into the gas inlet 110 of the carbon dioxide dissolving unit 200 in the absorbent liquid 142 conveyed through the absorbent liquid conveyance port 40 of the methane generating unit 100 ) Can dissolve carbon dioxide.

That is, according to an embodiment of the present invention, in order to dissolve carbon dioxide in the newly introduced biogas (BG), the absorbed liquid 142 returned may be reused.

Accordingly, the reused absorbent liquid 142 may include carbon dioxide already dissolved and carbon dioxide dissolved from the newly introduced biogas (BG).

Therefore, there is an effect that the source for producing methane is increased. Accordingly, the high-purity methane production system 1000, it is possible to easily produce a desired amount of methane from the source.

In order to produce the high-purity methane, according to another embodiment of the present invention, without the introduction of the new biogas (BG), the return of the absorbent liquid 142 not produced with methane may be performed.

Accordingly, the high-purity methane production system 1000 produces carbon dioxide dissolved in the absorbent liquid 142 as methane only with one inflow of the biogas (BG), and carbon dioxide not produced with methane is dissolved. The circulating process for conveying the absorbent liquid 142 may be repeatedly performed.

That is, the high-purity methane production system 1000, it is possible to produce an appropriate amount of methane by repeating the circulating process with only one inflow of the biogas (BG).

As described above, the methanation reaction tank 20 may reduce hydrogen ions contained in the absorbent liquid 142 to hydrogen molecules by the reductive metal (RM). Thereafter, by the methane-producing bacteria (MB), the reduced hydrogen molecules can be combined with carbon molecules of carbon dioxide dissolved in the absorbent solution 142 to produce methane.

However, according to an example, when the reductive metal (RM) and the methanogen (MB) coexist at a short distance, growth and biological metabolism of the methanogen (MB) may be inhibited.

Accordingly, the present invention provides a method for producing carbon dioxide dissolved in the absorbent liquid 142 as the methane without inhibiting the growth and biological metabolism of the methane producing bacteria (MB).

According to an embodiment of the present invention with reference to FIG. 4, the methane generating unit 100 may further include a carrier (S) to which the reducing metal (RM) is attached to the surface. Accordingly, the reducing metal (RM) and the methane-producing bacteria (MB) may be spaced apart from each other by the carrier (S).

Therefore, without inhibiting the growth and biological metabolism of the methane-producing bacteria (MB), it is possible to easily produce carbon dioxide dissolved in the absorption liquid 142 as the methane.

The carrier (S), like the reducing metal (RM), can reduce the hydrogen ions to hydrogen molecules. Accordingly, the methane-producing bacteria (MB) can be produced as methane by combining the reduced hydrogen molecules with carbon molecules of carbon dioxide dissolved in the absorbent liquid 142.

According to one embodiment, the size of the carrier may be 75 ~ 425 μm.

The carrier (S) may be at least one of an organic carrier or an inorganic carrier. For example, when the carrier (S) is an inorganic carrier, it can be obtained from scrap, slurry, or scale generated as a by-product in the steelmaking process.

According to one embodiment, the carrier (S), in addition to the reducing metal (RM), may be attached to the methane producing bacteria (MB). That is, the reductive metal (RM) and the methanogen (MB) are attached to different parts of the carrier (S), so that the reductive metal (RM) and the methanogen (MB) can be spaced apart.

According to one embodiment, in the process of reducing the hydrogen ions contained in the absorption liquid 142 in the methane generating unit 100 to hydrogen molecules, the reducing power of the reducing metal (RM) or the carrier (S) is exhausted Can be.

Alternatively, in the methane generation unit 100, in the process of combining the reduced hydrogen molecules with carbon molecules of carbon dioxide dissolved in the absorbent solution 142 to produce methane, the number of methane producing bacteria (MB) may decrease. Can.

Accordingly, the present invention provides a method for regenerating at least one of the reducing metal (RM), the methane producing bacteria (MB), or the carrier (S).

Referring back to FIG. 1, the high-purity methane production system 1000 may include a regeneration tank 500 in communication with the methane generating unit 100. The regeneration tank 500 may regenerate at least one of the reducing metal (RM), the methane producing bacteria (MB), or the carrier (S).

Accordingly, the regeneration tank 500 may regenerate at least one of reductive metal (RM), methane producing bacteria (MB), or carrier (S) that needs to be regenerated, provided by the methane generating unit 100. .

The regeneration tank 500 may return at least one of the regenerated reducing metal (RM), methane producing bacteria (MB), or a carrier (S) to the methane generating unit 100. Accordingly, the high-purity methane production system 1000, carbon dioxide in the biogas (BG) without reducing the reducing power of the reducing metal (RM) or the carrier (S), and the number of methane producing bacteria (MB) It can be easily produced with the methane.

According to an embodiment, the regeneration tank 500 may include a first regeneration tank for regenerating the reductive metal (RM) and a second regeneration tank for regenerating the carrier S. Accordingly, the reductive metal (RM) and the methane-producing bacteria (MB) can prevent coexistence of a short distance. Therefore, it is possible to prevent the growth and biological metabolism of the methane-producing bacteria (MB).

In the above, the high purity methane production system 1000 according to an embodiment of the present invention has been described. When using the high-purity methane production system 1000, it is possible to produce high-purity methane while removing carbon dioxide.

Hereinafter, a method for producing high-purity methane using the high-purity methane production system 1000 will be described in detail.

5 is a flowchart for explaining a method for producing high-purity methane according to an embodiment of the present invention, and FIG. 6 is a flowchart for explaining step S140.

Referring to Figure 5, the high-purity methane production method, the step of introducing a biogas containing carbon dioxide and methane (S110), the step of dissolving the carbon dioxide in the absorption liquid (S120), the carbon dioxide is dissolved in the absorption liquid Step (S130), preparing a carrier to which a reducing metal is attached (S140), reducing hydrogen ions contained in the absorbent liquid to hydrogen molecules by the reducing metal (S150), the reduced hydrogen molecules and the carbon dioxide It may include the step of producing methane by methane producing bacteria (S160), and the step of discharging the produced methane (S170).

Hereinafter, each step will be described.

Step S110

In step S110, biogas (BG) including carbon dioxide and methane may be introduced. Biogas (BG) may include 40-50% carbon dioxide and 50-60% methane.

As described above, according to an embodiment of the present invention, by the steps described below, by producing carbon dioxide in the biogas (BG) as methane, natural gas having a methane content of 93% or more can be produced.

Step S120

In step S120, the carbon dioxide may be dissolved in the absorption liquid 142. As described above, in the same condition, the solubility of carbon dioxide may be greater than that of methane. Accordingly, carbon dioxide in the introduced biogas (BG) may be dissolved in the absorbent liquid 142.

Meanwhile, in step 120, methane that is not dissolved in the absorbent liquid 142 in the biogas (BG) may be discharged and stored. That is, according to the object of the present invention, methane is collected from biogas (BG) and can be primarily stored.

Step S130

In step S130, the absorption liquid 142 in which the carbon dioxide is dissolved may be introduced.

The absorbent solution 142 in which the carbon dioxide is dissolved is provided to a reducing metal (RM), a carrier (S), and a methane producing bacteria (MB) in a step described below, and may be produced as methane.

Step S140

In step S140, it is possible to prepare a carrier (S) to which a reducing metal (RM) is attached.

According to an embodiment of the present invention, step S140 is not limited to the order and may be selectively performed. Specifically, in the step before step S130, it is not limited to the order and may be selectively performed.

To describe step S140 in more detail, reference will be made to FIG. 6.

Referring to FIG. 6, in step S140, preparing a reducing metal ion solution (S142), mixing a carrier with the reducing metal ion solution, preparing a mixed solution (S144), and the reducing metal on the carrier It may include the step of attaching the ions (S142). Hereinafter, each step will be described.

Step S142

In step S142, a reducing metal ion solution may be prepared.

In order to prepare the reducing metal ion solution, first, a reducing metal (RM) may be prepared. For example, the main component of the reducible metal (RM) may be iron, zero iron obtained from scraps generated as waste in the steelmaking process. Alternatively, the main component of the reducing metal (RM) may be nano-young iron obtained by synthesis.

In the solvent, the reducing metal (RM) may be added to prepare the reducing metal ion solution. For example, the solvent may be an aqueous ethanol solution of 95%, and the prepared reducing metal ion solution may be Fe ^{3 +} ionic solution.

Step S144

In step S144, the reducing metal (RM) ion solution may be mixed with a carrier (S) to prepare a mixed solution.

Prior to preparing the mixed solution, the carrier (S) may be prepared.

The carrier (S) may be prepared by acid treatment with an acidic solution. For example, the carrier (S) may be an inorganic carrier, and may be prepared by acid treatment with an acidic solution in which 10% hydrochloric acid and 10% nitric acid are mixed.

Thereafter, the acid-treated carrier (S) may be mixed with the reducing metal (RM) ion solution to prepare the mixed solution. For example, when the reducing metal (RM) ion solution is a Fe ³⁺ ionic solution, and the carrier is an inorganic carrier, a mixed solution of Fe ^{3 +} /inorganic carrier may be prepared.

Step S146

In step S146, a reducing agent may be added to the mixed solution. For example, the reducing agent may be an aqueous NaBH ₄ solution.

The reducing agent may be added to the carrier (S) while stirring the mixed solution to attach the reducing metal ion (RM). For example, while stirring the mixed solution at 300 rpm, the reducing agent can be attached by dropping at a slow speed.

Accordingly, in step S144, for example, the Fe ^{3 +} / Fe ^{3 +} ions of the mixed solution of the inorganic carrier described above are reduced to zero iron, and the zero iron can be attached to the inorganic carrier (S).

Thereafter, the solid obtained by adding a reducing agent to the mixed solution is washed and dried a plurality of times to obtain a carrier (S) to which the reducing metal (RM) is attached.

Referring to FIG. 5 again, steps S150 to S170 will be described.

Step S150

In step S150, hydrogen ions contained in the absorbent liquid provided from step S130 may be reduced to hydrogen molecules by the reducing metal (RM) provided through step S140.

In addition, the hydrogen ions can be reduced to hydrogen molecules by a carrier (S) to which the reducing metal (RM) is attached.

As described above, the carrier (S) may space the reducing metal (RM) and the methane-producing bacteria (MB).

Accordingly, the reductive metal (RM) and the methane-producing bacteria (MB) can prevent coexistence of a short distance. Therefore, it is possible to prevent the growth and biological metabolism of the methanogenic bacteria (MB).

Step S160

In step S160, the reduced hydrogen molecule and the carbon dioxide may be produced as methane by methane producing bacteria (MB).

According to one embodiment, the methane-producing bacteria (MB) may be anaerobic microorganisms. Accordingly, carbon dioxide can be produced as methane even in an oxygen-free environment.

Step S170

In step S170, the produced methane may be discharged.

As described above, in step 120, methane that is not dissolved in the absorbent liquid 142 in the biogas (BG) is discharged and stored first.

Thereafter, carbon dioxide dissolved in the absorption liquid 142 in the biogas (BG) in step S160 is produced as the methane, and is discharged in step S170 to be secondaryly stored.

Accordingly, according to an embodiment of the present invention, high purity methane can be produced from biogas (BG).

According to an embodiment of the present invention, steps S130 to S160 may be repeatedly performed repeatedly.

That is, in step S160, the absorption liquid 142 containing carbon dioxide that is not produced with methane may be introduced into step S130. Thereafter, while S140 to S170 are performed again, in step S160, the absorption liquid 142 containing carbon dioxide not produced with methane may be re-introduced to step S130.

Therefore, it is possible to produce high-purity methane by repeating this circulation process.

In this specification, a method for reducing carbon dioxide contained in biogas (BG) has been described as an example, but is not limited thereto. In the industry in which carbon dioxide such as steel, cement, or petrochemical is discharged in addition to the biogas (BG) It can also be used as a technology for carbon dioxide reduction.

Hereinafter, specific experimental examples of the present invention will be described.

7 is a photograph of a carrier according to Experimental Examples 1-1 and 2-1 of the present invention, and FIG. 8 is a photograph of a carrier having a reducing metal attached to the surfaces according to Experimental Examples 1-2 and 2-2 of the present invention. .

Referring to FIG. 7, carriers according to Experimental Example 1-1 having respective sizes of 75 μm to 2.8 mm, and carriers according to Experimental Example 2-1 having 75 to 425 μm were prepared.

That is, the carrier used in Experimental Example 1-1 contained many larger particles than the carrier used in Experimental Example 2-1.

In addition, referring to FIG. 8, a reducing metal (nano-young iron) was attached using each carrier used in FIG. 7, and in Experimental Example 1-2, the carrier of Experimental Example 1-1 and in Experimental Example 2-2 It was prepared by attaching a reducing metal to the carrier of Experimental Example 2-1.

9 is a view showing a comparison of the hydrogen generation amount of the carriers according to Experimental Examples 1-1 and 2-1 of the present invention, and FIG. 10 is a reducing metal according to Experimental Examples 1-2 and 2-2 of the present invention. This figure shows the characteristics of the amount of hydrogen generated by each attached carrier.

Referring to FIG. 9, it was confirmed that the maximum hydrogen generation amount of the carrier according to Experimental Example 1-1 was 6.74 μmol/g, and the maximum hydrogen generation amount of the carrier according to Experimental Example 2-1 was 32.48 μmol/g before the reducing metal was attached. Can be. Through these experimental results, as the carrier according to Experimental Example 2-1 of the present invention, that is, the carrier having a small particle size, has a large specific surface area, a high hydrogen generation amount (32.48 μmol/g) and a hydrogen generation rate (up to 7.24) μmol/d).

In addition, referring to FIG. 10, the maximum hydrogen generation amount of the carrier with the reducing metal according to Experimental Example 1-2 attached to the surface is 12.88 μmol/g, the maximum of the carrier with the reducing metal according to Experimental Example 2-2 attached to the surface. It can be seen that the amount of hydrogen generated is 150.61 μmol/g. Through these experimental results, when the reducing metal is attached to the carrier according to Experimental Example 2-2 of the present invention, that is, a carrier having a small particle size, both the amount of hydrogen generation and the rate of hydrogen generation are very high as it has a large specific surface area. Is showing.

In addition, when comparing the hydrogen generation properties of the carrier according to Experimental Example 2-1 in FIG. 9 and the carrier according to Experimental Example 2-2 in FIG. 10 (a carrier having a reducible metal attached to the surface), Experimental Example 2- It can be seen that the maximum hydrogen generation rate of the carrier according to 2 and the carrier on which the reducible metal is attached to the surface has increased significantly from 4.6 to 7.7 times.

Therefore, it can be seen that the carrier with the reducing metal attached to the surface according to the experimental example of the present invention is suitable for application to biomethane.

As described above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

1000: high purity methane production system
100: methane generating unit
10: absorbent liquid inlet
20: methanation reaction tank
30: Methane outlet
40: absorbent liquid return port
200: carbon dioxide melting section
110: gas inlet
120: carbon dioxide absorption tank
130: methane outlet
140: absorbent outlet
142: absorbent liquid
300: biogas provider
400: methane storage
500: regeneration tank
BG: Biogas
RM: reducing metal
MB: methane producing bacteria
S: carrier

Claims (14)

An absorption liquid inlet for receiving an absorption liquid in which carbon dioxide is dissolved;
A methanation reaction tank provided with a reductive metal for reducing hydrogen ions contained in the absorbent liquid to hydrogen molecules and a methane producing bacteria producing the reduced hydrogen molecules and the carbon dioxide as methane; And
High-purity methane production system having a methane generating unit comprising; methane outlet to discharge the produced methane.
According to claim 1,
A gas inlet through which biogas containing carbon dioxide and methane flows;
A carbon dioxide absorption tank for dissolving the carbon dioxide in an absorption liquid;
A methane outlet for discharging the methane; And
A high-purity methane production system comprising a carbon dioxide dissolving portion comprising; an absorption liquid outlet communicating with the absorption liquid inlet of the methane generating portion to provide an absorption liquid in which carbon dioxide in the carbon dioxide absorption tank is dissolved.
According to claim 2,
The methane generating unit,
A high-purity methane production system further comprising an absorption liquid return port for returning carbon dioxide that is not produced as methane in the methanation reaction tank to the carbon dioxide dissolution section.
According to claim 2,
A high-purity methane production system further comprising a biogas providing unit communicating with the gas inlet of the carbon dioxide melting unit and providing biogas.
According to claim 2,
A high-purity methane production system further comprising a methane storage unit through which the methane flows, in communication with the methane outlet of the methane generation unit and the methane outlet of the carbon dioxide melting unit.
According to claim 1,
The reducing metal further comprises a carrier attached to the surface,
The reducing metal and the methane-producing bacteria are spaced apart from each other by the carrier, high-purity methane production system.
The method of claim 6,
The carrier is a high-purity methane production system that reduces the hydrogen ions to hydrogen molecules.
The method of claim 6,
The size of the carrier is 75-425 μm, high purity methane production system.
According to claim 1,
The main component of the reducing metal is zero iron, high-purity methane production system.
Introducing an absorbent solution in which carbon dioxide is dissolved;
Reducing hydrogen ions contained in the absorbent liquid to hydrogen molecules by a reducing metal;
Producing the reduced hydrogen molecule and the carbon dioxide as methane by methane producing bacteria; And
The step of discharging the produced methane; high purity methane production method comprising a.
The method of claim 10,
Before the step of introducing the absorbent liquid,
A step of introducing biogas containing carbon dioxide and methane; And
Dissolving the carbon dioxide in the absorbent; high purity methane production method further comprising.
The method of claim 11,
In the step of dissolving the carbon dioxide in the absorbent liquid,
The method further comprises discharging methane contained in the biogas, high purity methane production method.
The method of claim 10,
A method of producing high purity methane further comprising the step of preparing a carrier to which the reducing metal is attached.
The method of claim 13,
The step of preparing a carrier to which the reducing metal is attached,
Preparing a reducing metal ion solution by adding a reducing metal in a solvent;
Preparing a mixed solution by mixing a carrier with the reducing metal ion solution; And
And adding a reducing agent to the mixed solution to attach the reducing metal ion to the carrier.

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