Abstract: A method for removing carbon dioxide from methane-containing crude gases, especially biogas, by pressure scrubbing, using a physical solvent, includes circulating the contaminated scrubbing solution after regeneration. A plant suitable for carrying out the method considerably reduces the methane loss which arises through methane slippage and improves the overall energy balance of the method. Laden scrubbing solution obtained from the pressure scrubbing is treated at least in one flash stage before the first stripping stage. In addition, a nitrogen, oxygen, carbon dioxide and methane-containing gas mixture drawn off from the flash stage is cleaned in a scrubbing stage by purified scrubbing solution drawn off from the second stripping stage and supplied in countercurrent, forming a high-purity methane gas.

Abstract: In a method for adsorptively drying purified biogas and regenerating laden absorbents, foreign matter is not allowed to enter the purified biogas, the content of methane in the gas remains virtually unchanged and the effort involved in regenerating the laden adsorbent is reduced. Drying and regeneration are effected in a closed biogas cycle, wherein separate layers based on silica gel and molecular sieves are used as the adsorbent. The biogas to be dried first flows through the silica gel layer. The adsorbent is regenerated with exclusively heated, dried biomethane having a temperature of up to 150° C. which, after contact with adsorbent, is recirculated to the outflow of purified biogas. After regeneration, the bed is cooled by biomethane, which is subsequently recirculated to the outflow of purified biogas. Methane-containing water accumulating during drying and regeneration is recirculated to the biogas generation and/or purification.

Abstract: A method for treating crude gas, in particular biogas, containing methane and carbon dioxide, in order to produce methane, and a plant suitable for carrying out the method. The method includes (a) washing the crude gas with an amine-containing washing solution, thereby forming a pure gas stream of methane and water, from which water is separated by subsequent cooling and condensation; (b) compressing and heating the washing solution containing CO2 and sulfur compounds and expanding the washing solution in a first expansion stage, during a secondary reaction time of 280 to 1200 seconds and at a constant reaction temperature; (c) cooling the purified washing solution and expanding it in a second expansion stage to normal pressure, whereupon any residual amounts of soluble CO2 and sulfur compounds are separated and the completely purified washing solution is cooled to normal temperature and returned to the washing stage.

Abstract: A method for regenerating an amine-containing scrubbing solution which is obtained during gas purification and in which CO2 and sulfur compounds are chemically bonded, as well as a system that is suitable for carrying out the method. The contaminated scrubbing solution is heated, compressed, and expanded in several stages such that CO2 and sulfur compounds are separated. The expanded scrubbing solution is subdivided into two partial streams, and one partial stream is recirculated into the process.

Abstract: In a method for adsorptively drying purified biogas and regenerating laden absorbents, foreign matter is not allowed to enter the purified biogas, the content of methane in the gas remains virtually unchanged and the effort involved in regenerating the laden adsorbent is reduced. Drying and regeneration are effected in a closed biogas cycle, wherein separate layers based on silica gel and molecular sieves are used as the adsorbent. The biogas to be dried first flows through the silica gel layer. The adsorbent is regenerated with exclusively heated, dried biomethane having a temperature of up to 150° C. which, after contact with adsorbent, is recirculated to the outflow of purified biogas. After regeneration, the bed is cooled by biomethane, which is subsequently recirculated to the outflow of purified biogas. Methane-containing water accumulating during drying and regeneration is recirculated to the biogas generation and/or purification.

Abstract: A method for separating methane and carbon dioxide from biogas and a device are intended for purifying biogas, wherein carbon dioxide is separated off from the biogas. The method is distinguished by an energetically favorable mode of operation. The biogas is passed under atmospheric pressure and standard temperature into an absorption column. While the biogas ascends through a packed bed, which has a surface area of 600 to 1200 m2/m3, and at a space velocity of 5 to 40 Nm3/m3h, carbon dioxide present in the biogas is bound in a wash liquid by chemosorption. The purified methane gas is taken off at the top of the absorption column at a defined flow velocity. Carbon dioxide bound in the wash liquid is removed by desorption at a relatively high pressure of 2 to 30 bar and a temperature of at least 120° C. Biogas may be separated into methane and CO2.

Abstract: A method and system produce a synthesis gas from a biogas. The method provides a more economic process control and a higher yield. For this purpose hydrogen sulfide and carbon dioxide of the biogas are nearly completely separated in separate cleaning steps before a catalytic conversion of the biogas, wherein hydrogen sulfide is biologically removed by the admixture of oxygen and/or oxidation agents containing oxygen. The oxygen, or the oxidation agent, is dosed such that an excess of oxygen of at least 1.0 vol.-% is present in the cleaned biogas (methane gas). The biogas is concentrated without any dehumidification, heated, and mixed with superheated steam. Due to the excess of oxygen, thermal energy is additionally created during the reforming process by an exothermal oxidation of oxygen contained in the biogas together with hydrogen in the catalyst bed for the endothermal conversion of methane to the synthesis gas.

Abstract: In a method for purifying biogas, components present in the biogas, such as carbon dioxide, sulfur compounds and ammonia, are separated in a plurality of different process stages. The method is characterized by low energy consumption and an increase in methane concentration of at least 10% while keeping methane losses low. In a first purifying step, carbon dioxide, hydrogen sulfide, ammonia and other organic water-soluble substances in the raw gas are removed at normal pressure or at overpressure of up to 6 bar in a wash column using fresh water, methane gas having a methane concentration of at least 65% is withdrawn at the head of the wash column. Methane and carbon dioxide dissolved in the washing water are sequentially separated from the contaminated washing water discharged from the washing stage in a first stripping column at normal pressure and subsequently in a second stripping column in a vacuum.

Abstract: A method and system produce a synthesis gas from a biogas. The method provides a more economic process control and a higher yield. For this purpose hydrogen sulfide and carbon dioxide of the biogas are nearly completely separated in separate cleaning steps before a catalytic conversion of the biogas, wherein hydrogen sulfide is biologically removed by the admixture of oxygen and/or oxidation agents containing oxygen. The oxygen, or the oxidation agent, is dosed such that an excess of oxygen of at least 1.0 vol.-% is present in the cleaned biogas (methane gas). The biogas is concentrated without any dehumidification, heated, and mixed with superheated steam. Due to the excess of oxygen, thermal energy is additionally created during the reforming process by an exothermal oxidation of oxygen contained in the biogas together with hydrogen in the catalyst bed for the endothermal conversion of methane to the synthesis gas.

Abstract: A method for regenerating an amine-containing scrubbing solution which is obtained during gas purification and in which CO2 and sulfur compounds are chemically bonded, as well as a system that is suitable for carrying out the method. The contaminated scrubbing solution is heated, compressed, and expanded in several stages such that CO2 and sulfur compounds are separated. The expanded scrubbing solution is subdivided into two partial streams, and one partial stream is recirculated into the process.

Abstract: A method for treating crude gas, in particular biogas, containing methane and carbon dioxide, in order to produce methane, and a plant suitable for carrying out the method. The method is characterized by improved profitability, produces high-purity methane of over 99.5% by volume, and at the same time distinctly lowers energy consumption for regenerating the washing solution. The method includes the following steps: (a) subjecting the crude gas under normal pressure or slight negative pressure to a one-stage or multiple-stage washing process with an amine-containing washing solution having an amine concentration of at least 15% at temperatures of up to 100° C., thereby forming a pure gas stream of methane and water, from which water is separated by subsequent cooling and condensation; (b) compressing the washing solution containing CO2 and sulfur compounds obtained after step (a) to a reaction pressure of at least 4 bar, heating the washing solution to a temperature of more than 120° C.

Abstract: A method for separating methane and carbon dioxide from biogas and a device are intended for purifying biogas, wherein carbon dioxide is separated off from the biogas. The method is distinguished by an energetically favorable mode of operation. The biogas is passed under atmospheric pressure and standard temperature into an absorption column. While the biogas ascends through a packed bed, which has a surface area of 600 to 1200 m2/m3, and at a space velocity of 5 to 40 Nm3/m3h, carbon dioxide present in the biogas is bound in a wash liquid by chemosorption. The purified methane gas is taken off at the top of the absorption column at a defined flow velocity. Carbon dioxide bound in the wash liquid is removed by desorption at a relatively high pressure of 2 to 30 bar and a temperature of at least 120° C. Biogas may be separated into methane and CO2.