Method and apparatus for biological production of synthetic methane

Abstract

The present invention relates to a method and an apparatus for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas to methane and water. The gas containing carbon monoxide and / or carbon dioxide is preferably biogas, flue gas or synthesis gas. The gas containing hydrogen is preferably a gas obtained from the electrolysis of water. The method and apparatus include efficient washing of the packaging material without removing it from the reactor, thereby maintaining and optimizing the conversion efficiency. In particular, the present invention relates to increasing the amount of green energy obtained from the anaerobic digestion of organic material by reducing the carbon dioxide content and increasing the methane content in the gas.

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for efficiently converting carbon monoxide and / or carbon dioxide and hydrogen in a gas to methane. The gas containing carbon monoxide and / or carbon dioxide is preferably biogas, flue gas or synthesis gas. The gas containing hydrogen is preferably a gas obtained from electrolysis of water. In particular, the present invention relates to a method and an apparatus for efficiently converting carbon monoxide and / or carbon dioxide and hydrogen in a gas to methane, including efficiently washing the packaging material without removing it from the reactor in order to optimize and maintain the conversion efficiency. The present invention also relates to converting hydrogen produced by electrolysis of water or similar techniques powered by renewable energy sources into renewable and storable energy such as methane. Furthermore, the present invention relates in one embodiment to increasing the amount of green energy obtained from the anaerobic digestion of organic matter by reducing the carbon dioxide content and increasing the methane content in biogas, which also reduces the amount of carbon dioxide released into the environment. [Background technology]

[0002] The rapid increase in the world population has led to a rapid increase in the demand for energy. Currently, the main sources of energy are carbon-containing fossil fuel sources such as coal, oil, and natural gas. However, it is said that energy sources produced from non-renewable energy will soon be exhausted. On the other hand, it is necessary to obtain energy to meet the demand by burning fossil fuels. Burning fossil fuels releases gases such as carbon dioxide, which have the greatest greenhouse effect, into the atmosphere, causing global warming.

[0003] With the growing interest in environmental protection around the world, many countries are moving towards the production of cleaner and more environmentally friendly energy as alternative energy sources, such as the use of renewable energy sources. One possible renewable energy source is biogas, which is a candidate because it contains methane that can be used to produce energy. The biogas is a by-product obtained by digesting organic matter in an anaerobic digester. The biogas is a renewable energy source, just like wind and solar power. However, rather than producing the biogas only to provide renewable energy, the production of the biogas has become very important in that it meets the prerequisite in modern life, that is, the sustainable treatment of organic waste resulting from the production of many products. Moreover, compared to wind and solar energy, the biogas has the advantage that it can be produced all year round, regardless of the weather. In contrast, wind and solar energy depend on whether the wind blows or the sun shines. Moreover, the biogas has the advantage that it can be stored.

[0004] The organic matter treated in the anaerobic digester is called the substrate and can come from a variety of sources, including animal waste from pigs, cows, chickens, food processing plants, breweries, palm oil mills, starch factories, ethanol plants, paper mills, municipal wastewater treatment plants, household waste sorting, etc. The anaerobic digester process produces digested water and biomass, where many harmful components are removed from the treated liquid so that it can be used for fertilizer or irrigation.

[0005] The anaerobic digestion process produces a gaseous by-product called biogas, which typically contains 50-70% methane (CH4), 30-50% carbon dioxide (CO2), and about 0.1-5.0% hydrogen sulfide (H2S).

[0006] The biogas can be an important resource as a renewable alternative to fossil fuels. However, before it can be used as an energy source, it is necessary to remove unwanted compounds from it. For example, before it can be used in a boiler or engine, it is necessary to remove the hydrogen sulfide contained in the gas to prevent corrosion of the equipment and because it is toxic to humans. Removal of hydrogen sulfide from the biogas is disclosed, for example, in European Patent Application No. 3487606 (A1). If the biogas is used directly to generate electricity in a combustion engine or boiler, carbon dioxide does not need to be removed. However, if the biogas is used as a replacement for natural gas, carbon dioxide must be removed or at least its content reduced in order to "upgrade" the biogas to biomethane and meet the specifications for use as natural gas. The resulting gas is also called renewable natural gas (RNG).

[0007] Several techniques are known for removing or reducing the carbon dioxide content in gases, such as absorption with chemical solvents, physical absorption with water scrubbing, cryogenic separation, membrane separation, and carbon dioxide fixation by biological or chemical methods. For example, European Patent Specification No. 2032709(B1) discloses a method for converting carbon dioxide and hydrogen to methane and water using methanogenic microorganisms in a bioreactor. When the methanogenic microorganisms are grown in a suitable liquid culture medium in the bioreactor / fermenter, gases containing carbon dioxide and hydrogen bubble up in the liquid. However, the drawbacks of bubbling the gases in the liquid to convert carbon dioxide and hydrogen to methane and water include: 1) the gases containing carbon dioxide and hydrogen do not disperse well throughout the liquid, 2) hydrogen gas is poorly soluble in water, and 3) the growth of microorganisms that freely swim in the liquid is not optimized.

[0008] The specification of European Patent No. 3013937 (B1) discloses a method and apparatus for biomethanation in which hydrogen and carbon dioxide are converted into methane in a reactor using methanogenic microorganisms. The method and apparatus include a reactor containing an aqueous medium, and the microorganisms are placed in the aqueous medium. The specification of European Patent No. 3013937 (B1) describes a reaction promotion device, and describes that the aqueous medium and the substrate gas can be mixed or stirred by supplying energy through a mechanical dynamic means, such as a nozzle or a stirrer, provided in the reaction promotion device.

[0009] Japanese Patent Application Publication No. 2004-041929 discloses a methane fermentation apparatus equipped with a fermenter containing microorganisms supported on a carrier.

[0010] US 2010 / 273242(A) discloses a biological desulfurization apparatus for biogas, which includes a reaction vessel and a carrier bed packed in the reaction vessel for attaching microorganisms.

[0011] As described above, as a method for converting carbon dioxide and / or carbon monoxide in a gas and hydrogen in a gas into methane, an improved method of the method is advantageous, and a method for efficiently converting carbon dioxide and / or carbon monoxide and hydrogen in a gas into methane and water is particularly advantageous. Summary of the Invention

[0012] It is therefore an object of the present invention to provide an improved method and apparatus for converting carbon dioxide and / or carbon monoxide and hydrogen in a gas into methane and water. Carbon dioxide and / or carbon monoxide are usually supplied from one gas source and hydrogen from another. According to the present invention, for example, the method and apparatus of the present invention are provided with an efficient scrubbing and depressurization system, which allows for a higher efficiency in converting carbon dioxide and / or carbon monoxide and hydrogen in a gas into methane and water. Furthermore, according to the present invention, the amount of green energy obtained by anaerobic digestion of organic substrates can be increased.

[0013] In particular, the objective of the present invention is to convert carbon dioxide and / or carbon monoxide from gas (e.g., gas from an anaerobic digester) and hydrogen produced from electrolysis of water (or similar technologies powered by renewable energy sources such as wind, solar, hydropower, etc.) into renewable energy. Said renewable energy (methane) can be stored as compressed or liquefied gas. The conversion of power from renewable energy into storable forms of energy is also known as Power-to-X. Thus, the present invention can also be described as a biological Power-to-X method and apparatus.

[0014] It is further an object of the present invention to provide a method and an apparatus for converting carbon dioxide and / or carbon monoxide in a gas and hydrogen in another gas into methane and water, which method and apparatus have improved efficiency in converting carbon dioxide and / or carbon monoxide and hydrogen into methane and water compared to the methods known in the prior art. The method and apparatus according to the present invention use a reactor containing a packaging material selected from the group of polyethylene, polypropylene, polystyrene, and acrylonitrile butadiene styrene (ABS plastic), which allows for a more efficient conversion of carbon dioxide and / or carbon monoxide and hydrogen in a gas into methane and water. The use of the packaging material disclosed above improves the distribution of gases containing carbon dioxide and / or carbon monoxide and hydrogen in the reactor. Furthermore, the growth conditions of microorganisms that convert carbon dioxide and hydrogen and / or carbon monoxide and hydrogen into methane and water are improved. The microorganisms can grow better on the surface of the packaging material than when they are directly in the liquid. The packaging material provides a large growth area necessary for the microorganisms to grow better. Furthermore, the packaging material in the present invention can be removed from the reactor. This allows the packaging material to be more easily cleaned and depressurized without having to remove it from the reactor, and allows the biosludge deposited on the packaging material to be removed. This avoids gas channeling, which occurs when the biosludge is compressed and deposited on the packaging material, forming channels in the packaging material that prevent the gas from being efficiently distributed in the reactor. Thus, the cleaning and depressurization system of the present invention improves the conversion of carbon dioxide and / or carbon monoxide and hydrogen in the gas to methane and water.

[0015] It is a further object of the present invention to provide an alternative method to the prior art.

[0016] One aspect of the invention is a method for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas into methane, comprising the steps of: a) providing a gas comprising carbon monoxide and / or carbon dioxide; b) providing a gas comprising hydrogen; c) directing the gas comprising carbon monoxide and / or carbon dioxide and the gas comprising hydrogen into a reactor, the reactor comprising a packaging material selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene (ABS), the reactor comprising carbon monoxide and / or carbon dioxide and a microorganism capable of converting hydrogen into methane, and the packaging material being removable from the reactor; d) providing a liquid and delivering said liquid to said reactor above said packaging material; e) directing the carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas through the packaging material containing the liquid and the microorganisms to convert the carbon monoxide and / or carbon dioxide and hydrogen into methane and water; f) directing the gas in which carbon monoxide and / or carbon dioxide and hydrogen have been converted to methane to an outlet; and g) filling the reactor with liquid and washing and depressurizing the packaging material (2) by blowing pressurized air into the reactor (1) below the packaging material (2); Includes.

[0017] Another aspect of the invention relates to a device for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas into methane, said device comprising: i) a reactor (1) comprising a packaging material (2), the packaging material being selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS) and acrylonitrile butadiene styrene (ABS), and having microorganisms growing on the surface of the packaging material capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane, the packaging material (2) being removable from the reactor (1); ii) an inlet (3) for feeding a gas containing carbon monoxide and / or carbon dioxide into the reactor (1); iii) an inlet (4) for supplying a hydrogen-containing gas to the reactor (1); iv) an inlet (5) for supplying liquid to the reactor (1); v) means (5A) for circulating liquid from a lower portion of the reactor (1) to an upper portion of the reactor (1) above the packaging material; vi) an outlet (6) for discharging carbon monoxide and / or carbon dioxide and the gas resulting from the conversion of hydrogen to methane; vii) an outlet (7) for discharging liquid from the reactor (1); and viii) an inlet (9) for blowing pressurized air into the reactor (1), the inlet (9) being located below the packaging material (2). Includes.

[0018] The present invention, and in particular preferred embodiments thereof, will now be described in more detail with reference to the accompanying drawings, which illustrate one way of practicing the invention and are not to be construed as limiting other possible embodiments within the scope of the appended claims. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of an apparatus used to convert carbon monoxide and / or carbon dioxide in a gas to methane, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in further detail below.

[0021] The method according to the present invention : In a first aspect, the present invention provides a method for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas into methane, comprising the steps of: a) providing a gas comprising carbon monoxide and / or carbon dioxide; b) providing a gas comprising hydrogen; c) directing the gas comprising carbon monoxide and / or carbon dioxide and the gas comprising hydrogen into a reactor, the reactor comprising a packaging material selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene (ABS), the reactor comprising carbon monoxide and / or carbon dioxide and a microorganism capable of converting hydrogen into methane, and the packaging material being removable from the reactor; d) providing a liquid and delivering said liquid to said reactor above said packaging material; e) directing the carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas through the packaging material containing the liquid and the microorganisms to convert the carbon monoxide and / or carbon dioxide and hydrogen into methane and water; f) directing the gas in which carbon monoxide and / or carbon dioxide and hydrogen have been converted to methane to an outlet; and g) filling the reactor with liquid and flushing and depressurizing the packaging by blowing pressurized air into the reactor below the packaging; The present invention relates to a method comprising the steps of:

[0022] The present invention relates to a method for converting carbon monoxide and / or carbon dioxide in combination with hydrogen in a gas into methane according to claim 1.

[0023] The gas containing carbon monoxide and / or carbon dioxide may be any gas containing carbon monoxide and / or carbon dioxide, although it is preferred that the gas containing carbon monoxide and / or carbon dioxide is an anaerobic gas.

[0024] In one embodiment, the gas comprising carbon monoxide and / or carbon dioxide is selected from the group consisting of biogas, flue gas and synthesis gas. In a preferred embodiment, the gas comprising carbon monoxide and / or carbon dioxide is biogas produced in an anaerobic digester.

[0025] Biogas is a waste / by-product gas produced in anaerobic digesters, where industrial and agricultural organic waste is treated in an oxygen-free environment. The organic matter treated in the anaerobic digesters could be fertilizer from livestock, food processing plants, breweries, palm oil mills, starch plants, ethanol plants, paper mills, municipal wastewater treatment plants and household waste sorting. The biogas obtained after treatment in the anaerobic digester is anaerobic, i.e. it does not contain oxygen. Another example of biogas is landfill gas, which is the biogas coming from landfills containing organic sediments.

[0026] Exhaust gas is the exhaust gas from a fireplace, oven, furnace, boiler, or steam generator that is discharged into the atmosphere through a flue, a pipe or channel that carries it. In most cases, the term refers to combustion exhaust gas from coal or biomass-based power plants and incinerators. For example, exhaust gas can be generated from thermal power plants, waste incineration plants, or cement plants. The composition of the exhaust gas varies depending on the material being burned, but it usually consists of nitrogen, carbon dioxide, and water vapor. It may also contain oxygen and small amounts of pollutants such as particulate matter (e.g., soot), carbon monoxide, nitrogen oxides, and sulfur oxides. Carbon dioxide may be present in the exhaust gas at a volume ratio of 10 to 25% or more.

[0027] Syngas is a fuel gas produced by pyrolysis and gasification of organic materials such as coal, biomass, and in principle any hydrocarbon feedstock such as wood, straw, etc. The composition of said syngas varies depending on the organic material used, but it usually consists of hydrogen, carbon monoxide, carbon dioxide, and methane.

[0028] The hydrogen-containing gas may be any gas containing hydrogen. For example, the hydrogen gas may be obtained by electrolysis of water or similar techniques. Hydrogen gas is supplied to the reactor in an amount such that at least a portion of the carbon dioxide and / or carbon monoxide in the gas is converted to methane and hydrogen dioxide (water). The amount of hydrogen supplied also depends on the amount of carbon monoxide and / or carbon dioxide in the gas led to the reactor. Thus, the amount of hydrogen supplied is not a required parameter in the present invention, but depends on the desired amount of carbon monoxide and / or carbon dioxide conversion.

[0029] The hydrogen gas may be added directly to the hydrogen gas before the gas containing carbon monoxide and / or carbon dioxide is introduced into the reactor, thereby introducing a mixture of the gas containing carbon monoxide and / or carbon dioxide and the gas containing hydrogen into the reactor. Alternatively, the gas containing carbon monoxide and / or carbon dioxide and the gas containing hydrogen may be introduced into the reactor separately. In a preferred embodiment of the invention, the gas containing carbon monoxide and / or carbon dioxide and the gas containing hydrogen are mixed before being introduced into the reactor.

[0030] In one embodiment of the invention, the amount of hydrogen-containing gas and the carbon monoxide and / or carbon dioxide-containing gas introduced into the reactor is controlled, for example by using a frequency-adjusted blower, for example to adjust the injection rate of the hydrogen-containing gas to the amount of carbon monoxide and / or carbon dioxide introduced, so that the amount of hydrogen is the amount required to convert the carbon monoxide and / or carbon dioxide to methane and water.

[0031] The reactor used in the method according to the invention is sometimes called a biotrickling filter or biotrickling reactor since it contains a packaging material.

[0032] An important aspect of the present invention is that the packaging material in the reactor is made of a material selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene (ABS). Polyurethane is another material known to be used as a packaging material. However, polyurethane is not suitable because it becomes too soft when exposed to pressure and / or high temperature. Packaging materials selected from polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene are more resistant to pressure based on their own weight than, for example, polyurethane. In a full-scale commercial plant, the packaging materials may be stacked up to a height of several meters. The packaging materials selected from polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene may be compressed by their own weight and the weight of the liquid when feeding liquid to the reactor (spraying the packaging material) and when biosludge forms on the packaging material. It is therefore important that the packaging material be periodically cleaned and depressurized in accordance with the present invention, as cleaning removes any accumulated biosludge and relieves any pressure that may have been applied to the packaging material.

[0033] Acrylonitrile butadiene styrene (ABS) is the toughest, followed by polystyrene, polypropylene, and polyethylene. By using the packaging material of the present invention in combination with the cleaning and depressurization system of the present invention, the packaging material can be stacked up to 10-12 meters high, even with temperatures in the reactor of up to 70°C. If a packaging material with low strength is selected, the packaging material will be compressed, reducing the surface area on which microorganisms can grow, and eventually the packaging material will be too compressed to allow gas and liquid to pass through the filter. Therefore, it is important to quickly and efficiently clean and depressurize the packaging material if it is compressed. Removing the packaging material from the reactor for cleaning takes time and stops the methanation process, i.e., the process of converting carbon dioxide and / or carbon monoxide in the gas to methane and water. The apparatus configuration of the present invention and the method of the present invention allow the packaging material in the reactor to be quickly and efficiently cleaned and depressurized. This provides an improved method and apparatus for converting carbon dioxide and / or carbon monoxide in the gas to methane and water.

[0034] Furthermore, the use of the packaging material in the reactor, instead of, for example, bubbling gas through a liquid as disclosed in the prior art, has several advantages. One of the advantages is improved growth of microorganisms, since the microorganisms grow better on the surface of the packaging material than in the liquid. The use of the packaging material allows a larger area for the growth of microorganisms. The liquid provided over the entire packaging material spreads on the surface of the packaging material in a thin film. The microorganisms grow on the surface of the packaging material in these thin films. Thus, the microorganisms can easily come into contact with hydrogen and convert the carbon dioxide and / or carbon monoxide in the gas into methane and water. Furthermore, since hydrogen is poorly soluble in water, the method of using a packaging material and a reactor containing only a small amount of liquid provided on the packaging material improves the solubility and distribution of the hydrogen gas in the reactor. However, the weight of the packaging material itself, the weight of the water provided to the reactor, and the weight of the accumulated sludge can cause the packaging material to be compressed. However, by providing a cleaning and decompression system, such as the method and apparatus of the present invention, that can quickly and efficiently clean and decompress the packaging material without removing the packaging material from the reactor, the problems of compaction of the packaging material and sludge buildup on the packaging material can be overcome.

[0035] Therefore, in one aspect of the present invention, the packaging material can be removed from the reactor. The packaging material can be removed from both the bottom and the side walls of the reactor. This allows the reactor to be efficiently cleaned.

[0036] The reactor containing the packaging material needs to be cleaned from time to time to avoid compaction or clogging of the packaging material. If the packaging material is compacted or clogged, the amount of gas and liquid passing through the packaging material will be reduced or completely blocked over time. This will reduce and eventually stop the conversion of carbon monoxide and / or carbon dioxide and hydrogen to methane. The cleaning can be done by filling the reactor with liquid, such as water or digester effluent, and then blowing pressurized air into the lower part of the reactor. The pressurized air is blown into the reactor below the packaging material. In this way, the packaging material is lifted from the bottom of the tank and moves freely through the liquid, thereby being cleaned. This cleaning avoids compaction of the packaging material and also removes the accumulated biosludge without the need to remove the packaging medium from the reactor to empty the reactor. Therefore, if the packaging material can be removed from the reactor, the reactor can be efficiently cleaned and depressurized.

[0037] The liquid applied during the washing step g) in the process according to the invention can for example be selected from the group consisting of water and anaerobic digester effluent. The liquid applied during the washing step can be the same liquid as the liquid fed to the reactor in step d) in the process according to the invention or it can be a different liquid. Preferably, the liquid fed in steps d) and g) is the same liquid.

[0038] The terms "biosludge" and "sludge" as used herein refer to a pile of solid matter.

[0039] In one embodiment of the invention, the pressurized air is blown into the reactor through an inlet that supplies the pressurized air, the inlet for the pressurized air being located below the packaging material, which in one embodiment may include two or more inlets for blowing pressurized air.

[0040] The inlets for supplying pressurized air are preferably two or more and are arranged at positions distant from each other. By configuring the pressurized air inlets in this way, the pressurized air can be supplied to the inside of the reactor so as to cover the entire cross section of the reactor, and the packaging material can be lifted and washed efficiently. Preferably, the pressurized air inlets are arranged at positions distant from each other. 2 The inlets are spaced apart from one another so as to provide one inlet for up to 7 m of cross-sectional area of ​​the reactor, preferably 2 The inlets are spaced apart from one another to provide one inlet for up to 5 m of cross-sectional area of ​​the reactor, for example 2 The inlets are spaced apart from one another so as to provide one inlet for up to 3 m of cross-sectional area of ​​the reactor, more preferably 2 The inlets are spaced apart so as to provide one inlet for up to 2 m of cross-sectional area of ​​the reactor, and most preferably 2 The inlets are spaced apart so as to provide one inlet for up to.

[0041] The microorganisms used in the present invention may be any microorganism capable of converting carbon monoxide and hydrogen and / or carbon dioxide and hydrogen into methane and hydrogen dioxide (water). Preferably, the microorganisms are methanogens, i.e. methanogenic microorganisms. The microorganisms are grown on the surface of the packaging material.

[0042] The microorganisms convert carbon dioxide and / or carbon monoxide into methane and water by reaction with hydrogen: -CO2+4H2→CH4+2H2O+heat -CO+3H2→CH4+H2O+heat

[0043] The amount of hydrogen depends on the amount of carbon dioxide present and the amount of carbon monoxide present, for example, if the gas contains only carbon dioxide and no carbon monoxide, then hydrogen should be provided, preferably 4 moles per mole of carbon dioxide.

[0044] The methanogen or autotrophic methanogen may be an anaerobic archaea. The methanogen may be used as one strain or in combination of two or more strains. The strain of the methanogen used in the present invention is not a specific strain, and any methanogen can be used. Thus, the present invention is not limited to a specific strain of the microorganism capable of converting carbon dioxide and / or carbon monoxide to methane. However, examples of methanogens suitable for the present invention are Methanobacterium, Methanobrevibacter, Methanothermobacter, Methanococcus, Methanosarcina, Methanopyrus, or mixtures thereof.

[0045] Examples of specific strains suitable for use are Methanobacterium thermoautotrophicum, Methanobacterium omelianskii, Methanobacterium formicicum, Methanococcus vanieri, Methanococcus barkeri, and Methanococcus thermoisotrophicus.

[0046] In the present invention, the microorganisms used to convert carbon monoxide and / or carbon dioxide and hydrogen to methane and water occur naturally in the effluent after processing in an anaerobic digester. This effluent can then be used to inoculate the process in the reactor. Once the process is started, the microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen to methane will grow and there will be no need to supply additional anaerobic digester effluent unless the reactor is not in operation for an extended period of time.

[0047] The effluent from the anaerobic digester can be derived from the digestion of any organic matter, e.g. from farm animals, food processing plants, breweries, palm oil mills, starch factories, ethanol plants, paper mills, municipal wastewater treatment plants, fertilizer from household waste sorting, etc. The composition of the effluent from the anaerobic digester depends on the organic matter / substrate that is degassed in the biogas reactor.

[0048] Additionally, the microorganisms require nutrients such as nitrogen (N), phosphorus (P) and potassium (K). In addition to methane and heat, the process also produces water. Excess water is drained from the reactor, but liquid is typically added to the reactor to provide nutrients to the process.

[0049] In one embodiment of the invention, the liquid is selected from the group of water and anaerobic digester effluent. When water is used as the liquid source in step d) of the method of the invention, fertilizer is fed to the water or fed directly to the reactor. The fertilizer may be an NPK fertilizer. When aerobic digester effluent is used as the liquid source, some or all of the nutrients are usually present in the effluent, reducing or eliminating the consumption of the NPK fertilizer.

[0050] It is also important to maintain the pH in the range of 6 to 8, which is the optimum pH value for microorganisms. Therefore, an appropriate base is added to the reactor to maintain the pH level. Alternatively, adding treated water from an anaerobic digester also serves to adjust the pH. In the present invention, the type of base to be added is not limited, and any base can be used.

[0051] It is important to provide the moisture and nutrients the microorganisms need to grow and to provide a liquid above the packaging material to cool the microorganisms.

[0052] The liquid can be fed to the reactor in step d) continuously or periodically.

[0053] When the liquid is supplied periodically in step d), the liquid can be periodically sprayed or the liquid can be periodically poured onto the packaging material and then drained.

[0054] However, in a preferred embodiment, in step d) the supply of the liquid to the reactor is carried out by continuous sparging. The continuous sparging of the liquid is preferably carried out at a flow rate of the liquid between 0.5 and 2.5 m per reactor cross-sectional area. 3 / m 2The liquid is sprayed over a range of 0.5 m 3 / m 2 The amount must not be less than 0.5 m 3 / m 2 If the flow rate is less than 0.5 m, the temperature in the reactor will rise and become higher than the optimum temperature for the microorganisms to grow. The liquid acts as a cooling medium. Furthermore, 3 / m 2 Less than this amount will result in biosludge forming and building up on the packaging material, resulting in reduced efficiency.

[0055] The flow rate is 2.5 m per reactor cross-sectional area. 3 / m 2 The flow rate should not exceed 2.5 m3, because too high a flow rate can cause stress to the microorganisms growing on the surface of the packaging material (biofilm). 3 / m 2 If the flow rate exceeds this amount, the biofilm (including microorganisms) will be washed away from the packaging material, and carbon dioxide and / or carbon monoxide will not be converted to methane. In order to efficiently convert carbon dioxide and / or carbon monoxide and hydrogen into methane, the flow rate should be 1.0 to 2.0 m 3 / m 2 Preferably, the flow rate is in the range of 1.2 to 1.8 m 3 / m 2 Most preferably, the flow rate is in the range of about 1.5 m 3 / m 2 It is.

[0056] In step d), the liquid fed to the reactor above the packaging material may in one embodiment be liquid recycled from a sump at the bottom of the reactor. If liquid in such a sump is recycled and fed to the top of the reactor, the sump may be cooled before feeding. Such cooling may be achieved using any known device suitable for such cooling.

[0057] The carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas are passed through the packaging material in which microorganisms are growing, and as the gas is passed through the packaging material, the microorganisms convert the carbon monoxide and / or carbon dioxide and hydrogen into methane and water.

[0058] The gas is applied, for example, to the top of the reactor above the packaging material, with co-current gas flow through the packaging material, and the gases from which carbon monoxide and / or carbon dioxide and hydrogen have been converted to methane are discharged through an outlet at the bottom of the reactor.

[0059] The gas is also applied to the lower part of the reactor, below the packaging material, with countercurrent gas flow through the packaging material, where the carbon monoxide and / or carbon dioxide and the gases from the conversion of hydrogen to methane are discharged through an outlet at the top of the reactor.

[0060] Whether the gas flow is co-current or counter-current depends on the design of the reactor.

[0061] Excess water produced in the reactor can be discharged through an outlet located at the bottom of the reactor, preferably below the packaging material.

[0062] The method according to the invention may also include a cooling system to dissipate the heat generated in the reactor during the conversion of carbon monoxide and / or carbon dioxide to methane, for example by using the liquid fed to the reactor to cool the reactor.

[0063] In one embodiment of the present invention, the temperature in the reactor needs to be in the range of 40°C to 65°C. The temperature in the reactor is maintained at the temperature by cooling the reactor. Any suitable cooling system can be used for the cooling, and the present invention is not particularly limited to the use of the cooling system. Usually, the reactor is cooled using a liquid supplied to the reactor. For example, when the reactor is cooled by recirculating wastewater from the bottom of the reactor to the reactor, the wastewater is passed through a cooling means before being supplied to the reactor. The cooling means usually refers to a heat exchanger. The temperature in the reactor needs to be kept in the range of 40°C to 65°C because the microorganisms grow in this temperature range. Preferably, the temperature in the reactor is 45°C to 60°C, which is the optimal temperature condition for the growth of the microorganisms.

[0064] The method according to the present invention may also include a heating system for supplying heat to the reactor. When carrying out the method, the treated water from an anaerobic digester is supplied to the reactor. The treated water contains microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane and water. However, in order to optimize the growth of the microorganisms, it is necessary to supply heat to the reactor to raise its temperature to 40°C to 65°C. Any suitable heating system may be used, and the present invention is not particularly limited in terms of the use of the heating system. For example, the heating may be performed using a heat exchanger. When carrying out the method, heat is generated due to the exothermic process, so cooling is required instead of heating.

[0065] In tropical climates, insulation of the reactor is not necessary, but in warm or cold climates the reactor may be insulated.

[0066] In a preferred embodiment of the method according to the invention, the cooling and heating system is a combined cooling and heating system.

[0067] The method according to the invention also includes stabilizing the pH of the liquid to maintain the pH between 6.0 and 8.0. The optimum pH for the growth of the microorganisms is in the range of 6.0 to 8.0. Any pH adjuster can be used for pH stabilization. However, in one embodiment of the invention, a decant and degassed treated liquid from an anaerobic digester is provided to stabilize the pH.

[0068] In the process, the pressure in the reactor is kept at a positive pressure of less than 200 mbar to prevent a vacuum from forming in the reactor. Thus, in one embodiment of the process according to the invention, the pressure in the reactor is less than or equal to 200 mbar.

[0069] Therefore, the method according to the present invention can efficiently and biologically convert carbon monoxide and / or carbon dioxide, obtained, for example, by electrolysis of water, and hydrogen, into methane. The method according to the present invention has the advantage that it can be carried out at room temperature (40 to 65°C) without applying pressure (less than 200 mbar). However, the method can also be carried out under a pressure in the range of, for example, 2 to 10 bar. Therefore, the pressure is not particularly limited in the method according to the present invention. In the catalytic process, a temperature of 250 to 900°C and a pressure of 10 to 30 bar are adopted. Furthermore, when using, for example, biogas as a gas, hydrogen sulfide is removed from a gas containing carbon monoxide and / or carbon dioxide before use, but since the method according to the present invention is not affected by the hydrogen sulfide, it is possible to use a "raw" biogas containing 3000 to 5000 ppm of hydrogen sulfide. However, since hydrogen sulfide is not necessary in the method according to the present invention, hydrogen sulfide may be optionally removed from the gas containing carbon monoxide and / or carbon dioxide before carrying out the method according to the present invention.

[0070] The method according to the invention allows to increase the methane content in gases such as biogas, flue gas, syngas, etc. For example, in the case of biogas, the methane content in said gas is increased from the usual 50-60% to more than 95%. Thus, the utilization rate of the biogas obtained from the anaerobic digester is significantly increased.

[0071] The liquid in the reactor may be discharged from the reactor, and in one embodiment the liquid discharged from the reactor is recycled to the reactor and provided above the packaging material in step d) or during the washing in step g).

[0072] In a preferred embodiment, the method according to the invention is anaerobic, i.e. the method is carried out under anaerobic conditions. Microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen to methane grow well under anaerobic conditions.

[0073] Apparatus according to the present invention : Reference will now be made to Figure 1, in particular the reference numerals given therein, which show a schematic diagram of an apparatus according to the present invention for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas to methane.

[0074] In a second aspect, the present invention relates to a device for converting carbon monoxide and / or carbon dioxide and hydrogen in a gas into methane, comprising: i) a reactor (1) comprising a packaging material (2), the packaging material being selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS) and acrylonitrile butadiene styrene (ABS), and having microorganisms growing on the surface of the packaging material capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane, the packaging material (2) being removable from the reactor (1); ii) an inlet (3) for feeding a gas containing carbon monoxide and / or carbon dioxide into the reactor (1); iii) an inlet (4) for supplying a hydrogen-containing gas to the reactor (1); iv) an inlet (5) for supplying liquid to the reactor (1); v) means (5A) for circulating liquid from a lower portion of the reactor (1) to an upper portion of the reactor (1) above the packaging material; vi) an outlet (6) for discharging carbon monoxide and / or carbon dioxide and the gas resulting from the conversion of hydrogen to methane; vii) an outlet (7) for discharging liquid from the reactor (1); and viii) an inlet (9) for blowing pressurized air into the reactor (1), the inlet (9) being located below the packaging material (2); Equipped with.

[0075] As shown in Figure 1, the apparatus comprises the reactor (1) containing the packaging material (2). The packaging material is selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene (ABS). Furthermore, the apparatus is configured to contain microorganisms growing on the surface of the packaging material, the microorganisms being capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane. The reactor may be made of a material that is resistant to the various components contained in the reactor, for example made of fiber reinforced plastic, stainless steel, or coated carbon steel.

[0076] In one embodiment of the device of the invention, the packaging material (2) can be removed from the reactor (1). Once the packaging material is removed from the reactor, it can be lifted by filling the tank with liquid and blowing pressurized air into the reactor through an inlet. This allows the accumulated biosludge to be removed from the reactor, thus preventing clogging or compaction of the packaging material. If the packaging material becomes clogged or compacted, the flow rate of gas or liquid through the packaging material will be reduced.

[0077] The inlet (9) for blowing in the pressurized air is preferably provided with two or more inlets for blowing in the pressurized air.

[0078] Preferably, there are two or more inlets (9) for supplying pressurized air, each of which is provided at a distance from the other. Such a configuration of the inlets for pressurized air allows the pressurized air to be supplied to the reactor over the entire cross section of the reactor, so that the packaging material can be lifted and washed efficiently. The inlets are preferably arranged at least 10 m2 of the cross section of the reactor. 2 Preferably, the reactor is arranged at a distance from each other so that there is one per 7 m of cross-sectional area of ​​the reactor. 2 For example, the reactor has a cross-sectional area of ​​5 m 2 and more preferably, the reactor is arranged at positions spaced apart from each other so that there is one per 3 m of cross-sectional area of ​​the reactor. 2 and most preferably at least one per 2 m of cross-sectional area of ​​the reactor. 2 They are placed far enough apart that there is one per 100.

[0079] The device comprises an inlet (3) for feeding a gas comprising carbon monoxide and / or carbon dioxide to the reactor (1) and an inlet (4) for feeding a gas comprising hydrogen to the reactor (1). In FIG. 1, the inlets (3) and (4) for feeding gas are arranged at the top of the reactor (1), above the packaging material (2). In this embodiment of the invention, the gas passes through the packaging material, the gas flow is cocurrent, i.e. in the same direction as the flow of the liquid, and the outlet (6) for discharging the carbon monoxide and / or carbon dioxide and the gas resulting from the conversion of hydrogen to methane is arranged at the bottom of the reactor (1). However, the inlets (3) and (4) for feeding gas may also be arranged at the bottom of the reactor (1), below the packaging material (2). In such an embodiment of the invention, the gas passes through the packaging material (2) and the gas flow is countercurrent, i.e. in the opposite direction to the flow of the liquid. When the gas flows in countercurrent, the outlet (6) is located at the top of the reactor (1), above the packaging material (2).

[0080] In Figure 1, the carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas are mixed before being fed to the reactor, however, in alternative embodiments of the invention, the carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas may be fed separately to the reactor.

[0081] The gas inlet may be provided with a blower (not shown) for directing the gas to the reactor (1). When the pressure of the gas is higher than the pressure inside the reactor, the blower may be replaced with a control valve (not shown) for controlling the flow rate of the gas to the reactor. When it is necessary to be able to control the amount of the gas containing carbon monoxide and carbon dioxide and the gas containing hydrogen when directing the gas to the reactor, it may be more preferable to use the blower in combination with the control valve. Furthermore, the above-disclosed means may be applied for adjusting the flow rate.

[0082] As indicated herein, the present invention also includes microorganisms growing on the surface of the packaging material (2) in the reactor (1). The microorganisms are any microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane and water. The microorganisms are preferably methanogenic microorganisms as disclosed above and may for example be any of the aforementioned microorganisms mentioned in the method of the present invention.

[0083] The apparatus further comprises an inlet (5) for feeding liquid to the reactor. The inlet (5) may be one or more inlets. The inlet (5) for feeding liquid is preferably located at the bottom of the reactor (1). The apparatus further comprises means (5A) for circulating liquid from the bottom of the reactor (1) to the top of the reactor (1) above the packaging material (2), the flow of the liquid being led through the packaging material. This provides the moisture necessary for the growth of the microorganisms. In the embodiment of the invention shown in FIG. 1, the inlet (5) is located at the bottom of the reactor (1), where it is mixed with the liquid already led through the packaging material, the mixed liquid being recirculated by the recirculation means (5A) and fed into the reactor at the top of the reactor (1) above the packaging material (2). The reactor is therefore equipped with the circulation means (5A) for circulating liquid from the bottom of the reactor (1) to the top of the reactor (1). The recycled liquid is typically passed through a cooling means, such as a heat exchanger, to cool the liquid before it is fed to the reactor. Thus, in one embodiment the apparatus also comprises a means for cooling the liquid fed to the reactor.

[0084] In another embodiment (not shown), the liquid inlet (5) can be located at a valve connected to the top of the reactor (1).

[0085] In a further embodiment of the present invention, the reactor (1) comprises a sparging means (8) for sparging the liquid into the reactor. The sparging means is preferably connected to a means (5A) for recirculating the liquid. Furthermore, the sparging means (8) may be provided with a control means for controlling the flow rate of the liquid sparged into the reactor. The flow rate of the liquid supplied to the reactor is preferably 0.5 to 2.5 m per cross-sectional area of ​​the reactor. 3 / m 2 More preferably, the range is 1.0 to 2.0 m. 3 / m 2 is the amount.

[0086] The apparatus also includes an outlet (6) for discharging the gas in which carbon monoxide and / or carbon dioxide and hydrogen are converted into methane. This gas is also called methane gas or biomethane gas. The gas containing carbon monoxide and / or carbon dioxide and hydrogen is converted into methane in the reactor, and the resulting biomethane gas is discharged from the reactor through the outlet (6).

[0087] Furthermore, the device preferably comprises an outlet (7) for discharging liquid from the reactor (1). When carbon monoxide and hydrogen and / or carbon dioxide and hydrogen are converted to methane, water is formed. Therefore, the water content in the reactor may increase, in which case some corresponding liquid will have to be discharged.

[0088] When the apparatus for converting carbon monoxide and / or carbon dioxide and hydrogen in the gas to methane is started, for example, a treated liquid from an anaerobic digester containing methanogenic microorganisms is supplied and the microorganisms are introduced into the reactor. The temperature in the reactor is increased by heating so that the optimum temperature for the growth of the microorganisms, i.e., the temperature in the reactor is in the range of 40 to 70°C. If the apparatus is prepared to convert carbon monoxide and / or carbon dioxide and hydrogen in the gas to methane, heating is no longer necessary since heat is generated after conversion. Instead, the reactor needs to be cooled in order to keep the temperature of the reactor in the range of 40°C to 70°C.

[0089] In one embodiment of the invention, the reactor (1) is equipped with a cooling system to dissipate the heat generated in the reactor during the conversion of carbon monoxide and / or carbon dioxide and hydrogen to methane.

[0090] In another embodiment of the invention, the reactor (1) is equipped with a heating system that provides heat to the reactor during start-up of the apparatus. The cooling and heating system may be a combined cooling and heating system.

[0091] The cooling and / or heating system is adapted to maintain the temperature within the reactor in the range of 40° C. to 70° C., which is optimal for microbial growth.

[0092] It should be noted that embodiments and features described in the context of one aspect of the invention also apply to other aspects of the invention, for example embodiments described in relation to the method of the invention also apply to the apparatus of the invention.

[0093] The invention is further illustrated in the following non-limiting examples. EXAMPLES

[0094] Example 1: Examples of compressing 1) polyurethane foam, 2) polyethylene, and 3) polypropylene as packaging materials are shown.

[0095] Each packaging material sample, 46 cm high, was placed in a pipe with an inner diameter of 100 mm. The temperature was 30°C. A load of 1.9 kg was applied to each pipe, resulting in a surface weight of 240 kg / m 2 A simulation was carried out to simulate the weight of liquid and biofilm on the packaging material used in the method and apparatus of the present invention. 2 A load of 0.05 was considered to be representative of a moderate load. After applying the load to each pipe, the height of the packaging was measured again to see how much the packaging had been compressed.

[0096] Table 1 below shows the height of various packaging materials before and after weight loading. [Table 1]

[0097] As mentioned above, when polyurethane is used as the packaging material, despite this typical moderate load, the packaging material is compressed by about 28%. Therefore, polyurethane foam is not suitable as a packaging material in the method and device according to the present invention. In contrast, polyethylene or polypropylene have a compression strength of 240 kg / m 2 It will not compress even if a load of

[0098] Example 2: 1) Polyethylene and 2) Polypropylene were used as packaging materials, and the difference in the degree to which they were compressed was investigated in examples where higher loads were applied.

[0099] Each packaging material sample was placed in a pipe with an internal diameter of 100 mm. The temperature was 32° C. A load of 48 kg was applied to each pipe, estimating that the maximum load expected to be exerted on the bottom of a 10 m high packaging material used in the present invention is 6000 kg / m2 per surface. 2 The reason for applying such a high load is that it is assumed that when wet biosludge accumulates on the surface of the packaging material, a load equivalent to the accumulation of the biosludge is applied to the packaging material.

[0100] Table 2 below shows the height of various packaging materials before and after weight loading. [Table 2]

[0101] As mentioned above, the polyethylene packaging material was compressed by 19 mm (corresponding to 4.19%) under a load of 48 kg, whereas the polypropylene packaging material was only compressed by 7 mm (corresponding to 1.54%) under this very high load.

[0102] From the above test results, it can be seen that when both polypropylene and polyethylene were used as the packaging material, the packaging material was compressed. The highest compression rate was observed when polyethylene was used as the packaging material.

[0103] As a result, the packaging material is compressed during the methanation process, and efficient cleaning and decompression according to the present invention is necessary to avoid clogging of the packaging material and reducing the conversion efficiency.

Claims

1. The following steps: a) providing a gas comprising carbon monoxide and / or carbon dioxide; b) providing a gas comprising hydrogen; c) directing the gas containing carbon monoxide and / or carbon dioxide and the gas containing hydrogen into a reactor, the reactor containing a packaging material selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), and acrylonitrile butadiene styrene (ABS), the reactor containing microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen into methane, and the packaging material being removable from the reactor; d) providing a liquid and feeding the liquid into the reactor above the packaging material; e) directing the carbon monoxide and / or carbon dioxide containing gas and the hydrogen containing gas through the packaging material containing the liquid and the microorganisms to convert the carbon monoxide and / or carbon dioxide and hydrogen into methane and water; f) directing the gas in which carbon monoxide and / or carbon dioxide and hydrogen have been converted into methane to an outlet; and g) filling the reactor with liquid and flushing and depressurizing the packaging material by blowing pressurized air into the reactor below the packaging material; A method for converting carbon monoxide and / or carbon dioxide and hydrogen in the gas into methane, comprising:

2. The method of claim 1 , wherein the microorganism is a methanogenic microorganism.

3. 10. The method of claim 1, wherein the liquid is selected from the group consisting of water and anaerobic digester effluent.

4. 10. The method of claim 1, wherein feeding liquid to the reactor is a continuous sparge.

5. The flow rate of the liquid in the continuous spray is 0.5 to 2.5 m per cross-sectional area of ​​the reactor. ３ / m ２ The method of claim 4, wherein the range is

6. 2. The method of claim 1, wherein the gas containing carbon monoxide and / or carbon dioxide is selected from the group consisting of biogas, flue gas, and synthesis gas.

7. 2. The method of claim 1, wherein the gas containing carbon monoxide and / or carbon dioxide is an anaerobic gas.

8. 10. The method of claim 1, wherein the temperature in the reactor ranges from 40°C to 70°C.

9. The method of claim 8 , wherein the method is carried out anaerobically.

10. The following equipment: i) a reactor (1) comprising a packaging material (2) selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS) and acrylonitrile butadiene styrene (ABS), wherein microorganisms capable of converting carbon monoxide and / or carbon dioxide and hydrogen to methane are growing on the surface of the packaging material, and the packaging material (2) can be removed from the reactor (1); ii) an inlet (3) for feeding a gas containing carbon monoxide and / or carbon dioxide into said reactor (1); iii) an inlet (4) for supplying a hydrogen-containing gas to the reactor (1); iv) an inlet (5) for feeding liquid into said reactor (1); v) means (5A) for circulating liquid from the lower part of the reactor (1) to the upper part of the reactor (1) above the packaging material; vi) an outlet (6) for discharging carbon monoxide and / or carbon dioxide and the gas resulting from the conversion of hydrogen into methane; vii) an outlet (7) for discharging liquid from the reactor (1), and viii) an inlet (9) for blowing pressurized air into the reactor (1), the inlet (9) being located below the packaging material (2); An apparatus for converting carbon monoxide and / or carbon dioxide and hydrogen in the gas into methane, comprising:

11. 11. Apparatus according to claim 10, wherein the reactor (1) comprises a dispersing means (8) for dispersing the liquid above the packaging material.

12. The spraying means (8) controls the flow rate of the liquid sprayed into the reactor to 0.5 to 2.5 m per cross-sectional area of ​​the reactor. ３ / m ２ 12. The apparatus of claim 11, comprising control means for controlling the range of

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