Method and apparatus for the biosynthesis of methane by means of methanogenic microorganisms

Abstract

The invention relates to a method for the biosynthesis of methane by means of methanogenic microorganisms, wherein a flushing of at least one growth body and / or of a reactor vessel is carried out by means of a cleaning liquid flowing in the opposite direction to the force of gravity, and to an apparatus for the biosynthesis of methane by means of methanogenic microorganisms.

Description

[0001] Method and apparatus for the biosynthesis of methane using methanogenic microorganisms

[0002] The invention relates to a method for the biosynthesis of methane using methanogenic microorganisms, wherein at least one growth body and / or a reactor container is rinsed by a cleaning fluid with a flow opposite to gravity, and to a device for the biosynthesis of methane using methanogenic microorganisms.

[0003] The biosynthesis of methane (also biological methanization) is a process for producing methane from hydrogen and carbon dioxide using methanogenic microorganisms, which usually takes place in a stirred tank reactor, trickling bed reactor or by membrane process.

[0004] DE 102005012 936 A1 describes a method for accelerating the commissioning and improving the biogas production of a biogas plant with immobilized methanogenic microorganisms, wherein the inoculation of packing materials with these methanogens and immobilization of the methanogens on these packing materials takes place before the commissioning of the entire biogas plant.

[0005] DE 10 2008 037 402 A1 describes a process for producing biogas by fermenting biomass in a biogas plant, comprising the following steps: fermentation of biomass in at least two stages, namely a hydrolysis stage and a first methanization stage; separation of the gas mixture produced in the first methanization stage into two gas components, wherein a first gas component consists predominantly of methane and a second gas component consists predominantly of carbon dioxide; introduction of the gas component consisting predominantly of carbon dioxide from the first methanization stage into the reactor of a second methanization stage; introduction of the hydrogen-containing hydrolysis gas obtained in the hydrolysis stage into the reactor of the second methanization stage; and conversion of the gases hydrogen and carbon dioxide to methane in the second methanization stage in the presence of methanogenic microorganisms.

[0006] DE 10 2011 051 836 A1 describes a method and a device for producing biogas in a biogas reactor, wherein the bioreactor contains packing material (biofilm) on the surface of which a biofilm is immobilized, containing methanogenic microorganisms, bacteria and optionally accompanying flora, and the packing material is sprinkled with a liquid, in particular consisting of water and nutrients (sprinkling liquid).

[0007] Kailuweit & Uhlemann | Patent Attorneys, whereby a liquid film forms on the surface of the packing material. The process comprises the flow of a reactant gas mixture of hydrogen and carbon dioxide in cocurrent or countercurrent flow with respect to the flow direction of the trickling liquid through the trickling bed.

[0008] DE 10 2013 209 734 A1 describes a process for the methanization of gases using trickle-bed reactors with staged addition of carbon dioxide, and an apparatus for carrying out the process comprising a reactor filled with growth media containing methanogenic microorganisms immobilized on the surface of the growth media, arranged along the longitudinal axis of the cylindrical section of the reactor. Carbon dioxide is added in stages. Preferably, the reactor is designed as a tube. Cooling is achieved via the trickling liquid, in particular by increasing the volume of the trickling liquid. This leads to an increase in the thickness of the liquid film over the biofilm consisting of methanogens, a significant deterioration of the mass transfer between the biofilm and the reactant and product gases, and thus a reduction in conversion.

[0009] DE 10 2020 109 419 A1 describes biological methanization, in which hydrogen and carbon dioxide are converted to methane with the formation of water, in a tubular reactor, thereby enabling intensive contact between the introduced gas and the microorganisms and thus increasing the efficiency.

[0010] DE 102017 120658 A1 describes a trickle body with a support structure that forms channels which are at least partially filled with a porous packing material and its use in an exhaust air purification system.

[0011] Methanation in a trickling bed typically takes place in a reactor that is wholly or partially filled with a bed of growth media containing a biofilm of immobilized methanogenic microorganisms. This biofilm grows gradually. Excess microbial sludge, as well as solids introduced with the inoculation sludge, can reduce or even completely block the free passage of the bed within the reactor. Therefore, this excess sludge must be removed regularly. This is commonly done by emptying the reactor and externally cleaning the growth media or by completely replacing the growth media with new ones. However, this cleaning process is complex and interrupts methane production for the duration of the cleaning or replacement. Furthermore, it can lead to a reduction in gas quality.

[0012] Kailuweit & Uhlemann | Patent Attorneys CN 1 07002 014 A describes methods and bioreactors for microbial digestion using immobilized biofilms. These methods employ inserts comprising one or more baffles that form at least two open chambers. CN 1 07002 014 A discloses a process of rinsing the fermenter with tap water, the volume of which corresponds to twice the volume of the fermenter (at room temperature).

[0013] WO 2023 / 147905 A1 describes a process for the biotechnological production of methane comprising cleaning the packing material without removing it from the reactor. The cleaning process involves flooding the reactor with a liquid and injecting compressed air below the packing material, thus decompressing it. A disadvantage is that the use of compressed air, i.e., an oxygen-containing gas mixture, can inhibit the anaerobic process of biotechnological methane production due to a toxic effect on the methanogenic microorganisms, resulting in a loss of biomass activity. Furthermore, the use of air (oxidizing agent oxygen) in a fuel-containing reactor (hydrogen and methane) poses a risk of forming an explosive atmosphere. WO 2023 / 147905 A1 discloses an outlet in the lower part of the reactor, preferably below the packing material (page 16, paragraph 7).

[0014] The task is therefore to provide a process or device for the biosynthesis of methane using methanogenic microorganisms, which features simplified purification or purification that reduces idle times in methane production, increases safety and / or increases the efficiency of the reaction.

[0015] According to the invention, the problem is solved by the method and the apparatus according to the independent claims. Advantageous embodiments of the invention are specified in the dependent claims.

[0016] A first aspect of the invention relates to a process for the biosynthesis of methane using methanogenic microorganisms, comprising the steps of:

[0017] a) Inoculation of a surface of at least one growth body with methanogenic microorganisms in a reactor vessel,

[0018] b) Introducing a process fluid comprising nutrients and water at the top of the reactor vessel, wherein the surface of the at least one

[0019] Kailuweit & Uhlemann I Patent Attorneys Growth body with the methanogenic microorganisms comes into contact with the process fluid,

[0020] c) Introducing a gaseous substrate comprising carbon monoxide or carbon dioxide and hydrogen into the reactor vessel, wherein the surface of the at least one growth body with the methanogenic microorganisms comes into contact with the gaseous substrate,

[0021] d) Discharge of the methane produced from the reactor vessel,

[0022] characterized in that at least one rinsing of the at least one growth body and / or reactor container by a cleaning fluid with a flow opposite to gravity at an empty tube velocity in the range of 5 m / h to 200 m / h takes place before, during and / or after step d).

[0023] In embodiments, the process is carried out in the sequence of process steps a), b), c) and d). In embodiments, the process is carried out in the sequence of process steps b), c) and d) simultaneously and after step a). In embodiments, the rinsing of the at least one growth body and / or reactor vessel by a cleaning fluid with a flow against gravity at an empty tube velocity in the range of 5 m / h to 200 m / h is carried out after step d).

[0024] Advantageously, the methanogenic microorganisms form a biofilm on the at least one growth medium and convert the gaseous substrate, comprising carbon monoxide or carbon dioxide and hydrogen, into methane. Advantageously, microbial growth, or biomass growth, occurs during the process.

[0025] In certain embodiments, the reactor vessel is a trickle-bed reactor. A "trickle-bed reactor" is understood to be a reactor in which a process fluid (liquid phase) trickles over at least one growth medium, in particular a fixed bed, i.e., the fixed bed is brought into contact with the process fluid from above, while a gaseous substrate simultaneously flows through the fixed bed. Advantageously, the gaseous substrate is the main reactant stream. In certain embodiments, the gaseous substrate flows through the fixed bed in either co-current or counter-current flow to the process fluid, preferably co-current flow.

[0026] In embodiments, the at least one growth body is a fixed bed packing or a heat exchanger.

[0027] Kailuweit & Uhlemann I Patent AttorneysIn embodiments, the fixed bed consists of solid bodies or porous particles, in particular spheres, hollow cylinders or particles with heterogeneous surfaces.

[0028] In some embodiments, the fixed bed is made of plastic particles. In other embodiments, the plastic particles are made of polyethylene, polypropylene, or recycled materials. In other embodiments, the fixed bed is made of wood chips.

[0029] In embodiments, the solid bodies or porous particles have a mean diameter in the range of 5 mm to 50 mm, preferably in the range of 17 mm to 40 mm.

[0030] In embodiments, the at least one growth body is a porous fixed-bed packing.

[0031] In embodiments, the at least one growth body is a fixed bed made of hydrophobic plastic with a large volume-specific surface area.

[0032] In some embodiments, the at least one growth body acts as a heat exchanger. Advantageously, the use of a heat exchanger for temperature control and as a growth surface for microorganisms in biotechnological reactors can maintain the stability of the biological system and productivity across the entire cross-section of the reactor. The term "heat exchanger" refers to a device that transfers thermal energy between at least two materially separate systems, in particular from a heat transfer fluid to a fluid stream or from a fluid stream and / or a stationary heat source, for example, heat of reaction, to a heat transfer fluid.

[0033] The term "heat transfer fluid" refers to a medium, in particular a gas or liquid, that transports heat from one location to another in a heating or cooling circuit. A heat transfer fluid ideally has a high specific heat capacity, low viscosity, and constant chemical and physical properties within its operating temperature range.

[0034] In embodiments, the growth body is a heat exchanger comprising at least one compartment which is designed to convey a heat transfer fluid and from which heat is removed from the reactor vessel by means of the at least one heat exchanger via the heat transfer fluid.

[0035] Kailuweit & Uhlemann I Patent AttorneysIn embodiments, the at least one compartment is an elongated hollow body, preferably a tube or a rectangular hollow body, in particular a square hollow body.

[0036] A "rectangular hollow body" or "square hollow body" refers to a hollow body with a rectangular or square cross-section.

[0037] In particularly preferred embodiments, the at least one compartment is a tube.

[0038] A "tube" is understood to be a hollow body with a circular or oval cross-section.

[0039] In embodiments, the at least one tube is designed as a straight tube, a bent tube, a ring, or a flat or spatial spiral.

[0040] In embodiments, the at least one compartment consists of a biologically and / or chemically inert, thermally conductive material, preferably steel.

[0041] Advantageously, the heat transfer fluid is selected based on its boiling point, the desired temperature range (target temperature), its non-toxicity to microorganisms (in case of leaks), its environmental compatibility, and / or that the pressure corresponding to the boiling point is only slightly (a few bar overpressure at most) above the reactor internal pressure to avoid excessively thick walls. In embodiments, the heat transfer fluid is selected from water, ammonia, carbon dioxide, or hydrocarbons, in particular ethane, propane, butane, isobutane, or pentane, preferably from water or hydrocarbons, and especially preferably water or pentane.

[0042] In embodiments, the surface of the at least one growth body comprises a hydrophobic material, preferably polyolefin. Advantageously, the microorganisms grow well on hydrophobic materials.

[0043] In embodiments, the surface of the at least one growth body has a hydrophobic coating, preferably a coating with synthetic resin. Advantageously, the synthetic resin coating is applied as a lacquer in an immersion bath. Advantageously, the hydrophobic coating, in particular the synthetic resin, is non-toxic to microorganisms, especially

[0044] Kailuweit & Uhlemann I Patent Attorneys states that the hydrophobic coating, in particular the synthetic resin, contains no organic solvents and / or color pigments with heavy metals.

[0045] In embodiments, at least one surface-enhancing element is arranged on the surface of the at least one growth body. In embodiments, the at least one surface-enhancing element is selected from the group comprising helical, porous, rib-shaped, lattice-like, or spherical structures, in particular ribs, fins, pins, and bumps. Advantageously, the surface-enhancing element increases the surface area and / or provides a larger growth area for microorganisms. Furthermore, the surface-enhancing element, in particular ribs, fins, pins, and / or bumps, advantageously increases the conversion rate of a biotechnological reaction comprising a gas-liquid phase transition, in particular methanation.

[0046] In some embodiments, step a) is performed only once. In other embodiments, step a) is repeated after rinsing with cleaning fluid.

[0047] In embodiments, the inoculation of a surface with methanogenic microorganisms in step a) involves the immobilization of the methanogenic microorganisms, preferably by the simultaneous application of accompanying organisms that form adhesive proteins. Advantageously, the accompanying organisms that form adhesive proteins adhere to hydrophobic surfaces.

[0048] The term "adhesion protein" (also adhesion proteins, adhesion molecules) refers to mixtures of proteins and polysaccharides with lipids, phospholipids, glycoproteins, glycolipids, nucleic acids, especially extracellular DNA and / or lipopolysaccharides, which adhere to surfaces by adhesion as "extracellular polymeric substances (EPS)".

[0049] In embodiments, the inoculation of a surface with methanogenic microorganisms in step a) is carried out by means of an inoculum, preferably an inoculum comprising methanogenic microorganisms and accompanying organisms which form adhesive proteins, particularly preferably sewage sludge and / or manure.

[0050] Kailuweit & Uhlemann I Patent AttorneysIn embodiments, the inoculation of a surface with methanogenic microorganisms takes place in step a) by contacting the surface of the at least one growth body with the inoculum.

[0051] Advantageously, inoculating a surface with methanogenic microorganisms in step a) forms a biofilm with a layered structure ranging in thickness from 0.05 pm to 0.1 pm. This biofilm exhibits a layering of various microorganisms involved in metabolism, which leads to exceptional stability of the degradation process and the entire reaction process within the reactor vessel.

[0052] In some embodiments, step b) occurs after step a). In others, step b) occurs simultaneously with step c). In still others, step b) occurs simultaneously with step c) and step d). In still others, steps b) and c) begin before step d), and in continuous operation, steps b), c), and d) occur simultaneously.

[0053] In embodiments, the introduction of the process fluid in step b), the introduction of a gaseous substrate in step c) and / or the discharge of the formed methane in step d) is carried out continuously.

[0054] In embodiments, the process fluid is an aqueous solution or water. In embodiments, the process fluid comprises nutrients, in particular macroelements selected from ammonium (NH4), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), phosphorus (P), sodium (Na), and sulfur (S) salts, and microelements (also trace elements) selected from manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), zinc (Zn), cobalt (Co), and copper (Cu) salts.

[0055] The term "nutrients" refers to inorganic substances necessary for maintaining the living conditions for microorganisms. In certain embodiments, the nutrients are selected from salts of the elements nitrogen (N), Ca, Fe, K, Mg, P, Na, S, Mn, Mo, Ni, Se, Zn, Co, and Cu.

[0056] Advantageously, the liquid in the reactor (process liquid) forms a liquid film (free-flowing liquid) that flows or trickles downwards over the at least one growth medium, in particular the fixed bed. This liquid film supplies the biofilm of methanogenic microorganisms with water and nutrients.

[0057] Kailuweit & Uhlemann | Patent Attorneys. In embodiments, step b) is carried out continuously. The term "continuous" refers to a steady process or process step that continues over a long period of time. Advantageously, the continuous introduction of the process fluid keeps the biofilm of microorganisms on the at least one growth medium and / or in the reactor vessel moist.

[0058] In embodiments, step b) is carried out quasi-continuously. The term "quasi-continuous" refers to a continuous process or process step that runs over a longer period of time and is interrupted at regular intervals, i.e., it runs almost continuously.

[0059] In some embodiments, the process fluid is introduced in step b) in a uniform distribution across the (horizontal) cross-section of the reactor vessel. In other embodiments, the uniform introduction of the process fluid in step b) is achieved by at least one distribution device at the upper end of the reactor vessel.

[0060] In embodiments, step b) involves a continuous recirculation of a process fluid comprising nutrients and water into the reactor vessel, whereby the surface of the at least one growth body with the methanogenic microorganisms comes into contact with the process fluid.

[0061] The term "recirculation" refers to the process fluid being passed through the reactor vessel, whereby the process fluid is drained at the lower end of the reactor vessel and reintroduced at the upper end of the reactor vessel.

[0062] In some embodiments, step c) is performed after step a). In others, step c) is performed continuously.

[0063] According to the invention, the gaseous substrate comprises carbon monoxide (CO) and hydrogen (H2) or carbon dioxide (CO2) and hydrogen (H2).

[0064] In embodiments, the gaseous substrate comprising carbon monoxide or carbon dioxide and hydrogen further comprises hydrocarbons and / or hydrocarbon compounds, which optionally contain heteroatoms such as oxygen, nitrogen, sulfur or halogens.

[0065] Kailuweit & Uhlemann I Patent Attorneys. In embodiments, the gaseous substrate comprises biogas and / or raw biogas as the carrier of the carbon dioxide.

[0066] In some embodiments, step c) is carried out by introducing a gaseous substrate, wherein the gases carbon monoxide or carbon dioxide and hydrogen are not present in a stoichiometric ratio. Due to the different solubilities of carbon dioxide and hydrogen in the liquid phase, the proportion of dissolved carbon dioxide is greater than that of dissolved hydrogen.

[0067] In some embodiments, step c) is carried out by adding hydrogen and a substoichiometric amount of carbon dioxide such that the gases dissolved in the process fluid (also called free-flowing fluid) are in a stoichiometric ratio. The gas concentrations corresponding to the stoichiometric ratio in the fluid can be calculated using the respective sorption isotherms of the two gases, hydrogen and carbon dioxide, whereby, for simplicity, only the carbon dioxide is considered. Advantageously, the lower concentration of dissolved carbon dioxide prevents over-acidification and thus achieves increased process stability.

[0068] In embodiments, the gaseous substrate in step c) is guided in parallel flow, counterflow, crossflow or other flow variants relative to the process liquid in step b).

[0069] In some embodiments, the gaseous substrate is introduced at the upper end of the reactor vessel. In other embodiments, the gaseous substrate is guided past the growth body, in particular through the fixed bed packing.

[0070] In some embodiments, step c) is carried out by a staged introduction of gaseous substrate, in particular carbon dioxide. "Staged introduction" or "addition" refers to the introduction at the individual trays of the reactor vessel. In some embodiments, the gaseous substrate is controlled by a regulating device at each of the individual trays of a reactor vessel. Advantageously, a high methane concentration in the product gas, preferably > 99% (v / v), is achieved by a staged addition of the gaseous substrate.

[0071] In some embodiments, step d) is performed after step a). In other embodiments, step d) is performed continuously.

[0072] Kailuweit & Uhlemann | Patent Attorneys. In some embodiments, the methane produced is discharged from the bottom of the reactor vessel (direct current). In other embodiments, the methane produced is discharged from the top of the reactor vessel (countercurrent).

[0073] In some embodiments, the gaseous substrate is discharged from the bottom of the reactor vessel. In other embodiments, the discharged gaseous substrate is fed back into the reactor vessel from the top.

[0074] In some embodiments, water formed during the biosynthesis of methane is also drained away.

[0075] In some embodiments, a nutrient solution comprising nutrients and water is introduced into the reactor vessel, whereby the surface of the at least one growth body containing the methanogenic microorganisms comes into contact with the nutrient solution. In some embodiments, the introduction of the nutrient solution is quasi-continuous or discontinuous. Advantageously, the process fluid is analyzed, and nutrient solution is introduced once a certain minimum nutrient concentration is reached in the process fluid. In some embodiments, the introduction of the nutrient solution occurs once every two days up to five times per day, preferably once per day.

[0076] In embodiments, the nutrient solution further comprises methanogenic microorganisms.

[0077] In embodiments, the method, in particular steps a), b), c) and / or d), is carried out at a temperature in the range of 20°C to 90°C, preferably in the range of 35°C to 75°C.

[0078] In some embodiments, the process is carried out at increased system pressure. This advantageously compensates for the low partial pressure or low solubility of hydrogen in the liquid. According to Henry's law, the concentration of hydrogen in the liquid then increases, so that a larger amount of hydrogen per unit volume of liquid is available for biochemical methane production. Within certain limits, the specific conversion is proportional to the partial pressure of hydrogen in the liquid.

[0079] In embodiments, the reactor vessel is operated at an overpressure in the range of 0.02 bar to 100 bar (relative to atmospheric pressure), preferably in the range of 0.02 bar to 50 bar (relative to atmospheric pressure).

[0080] Kailuweit & Uhlemann I Patent AttorneysIn embodiments, the reactor vessel is operated at an overpressure in the range of 0.02 bar to 10 bar (with respect to atmospheric pressure).

[0081] According to the invention, the rinsing of the at least one growth body and / or reactor container is carried out by a cleaning fluid with a flow in the opposite direction to gravity at an empty tube velocity in the range of 5 m / h to 200 m / h, preferably in the range of 10 m / h to 70 m / h, particularly preferably at about 50 m / h.

[0082] The phrase "opposing gravity" refers to a flow direction that is directed "upwards", i.e., starting from the Earth's surface at an angle in the range of 120° to 240°, preferably in the range of 135° to 225°, and particularly preferably about 180°.

[0083] Advantageously, the flow directed against gravity at the at least one growth body enables an abrasive flow as well as direct collisions between the fluidized growth bodies. Furthermore, the particles of sludge and deposits are advantageously suspended from the reactor vessel and / or from the at least one growth body and carried away with the cleaning fluid. Advantageously, methane biosynthesis can continue due to the microorganisms present in the suspension of the sludge with the cleaning fluid, thus maintaining product gas quality and productivity, and therefore preventing any disruptions to normal operation.

[0084] In some embodiments, the rinsing is carried out continuously or discontinuously.

[0085] Pursuantly, the purging of at least part of the reactor vessel or the entire reactor vessel is carried out by adjusting the empty pipe velocity.

[0086] The term "empty tube velocity" refers to the quotient of volume flow rate (velocity of a gas or liquid flow) and the free cross-sectional area of ​​the reactor vessel.

[0087] In embodiments, the rinsing for at least a part of the reactor vessel or for the entire reactor vessel is carried out by means of at least one further inlet for cleaning fluid, wherein the at least one further inlet is arranged on at least one side surface of the reactor vessel, preferably in the area of ​​the at least one growth body.

[0088] Kailuweit & Uhlemann | Patent Attorneys. In some embodiments, the cleaning fluid is water or an aqueous solution. In others, the cleaning fluid is a process fluid, in particular a diluted process fluid. In still others, the cleaning fluid and the process fluid are the same.

[0089] In embodiments, the rinsing of the at least one growth body and / or reactor vessel takes place after a pressure loss of at least 10%, in particular after a pressure loss of 20%, with respect to the initial pressure inside the reactor vessel.

[0090] In embodiments, the rinsing of the at least one growth body and / or reactor container takes place approximately 1 to 24 times per year, preferably once per month.

[0091] In embodiments, the rinsing of the at least one growth body and / or reactor vessel is carried out by means of a cleaning fluid with a flow in the opposite direction to gravity using a bistable hydraulic overflow valve or by means of a pump.

[0092] In embodiments, the rinsing of the at least one growth body and / or reactor vessel is carried out by means of a bistable hydraulic valve, which opens the drain of a higher-level tank containing the cleaning fluid depending on the fill level and lets this fluid in at the lower end of the reactor.

[0093] In some embodiments, the purging is carried out in combination with a variation of the flow conditions of the cleaning fluid, the use of ultrasound, and / or by introducing gas, in particular oxygen-free gas, at the lower end of the reactor, preferably at the bottom of the reactor vessel, and / or at the side surfaces of the reactor vessel. In other embodiments, the purging is carried out in combination with the introduction of gas (cleaning gas) at the lower end of the reactor vessel, preferably at the bottom of the reactor vessel, after the reactor vessel is at least nearly flooded, in particular after a trickle bed in the reactor vessel is largely flooded, i.e., the spaces normally filled with gaseous substrate are largely filled with cleaning fluid.

[0094] Kailuweit & Uhlemann | Patent Attorneys The term "normal operation" refers to process steps b), c), and d). In embodiments, during normal operation, the process fluid is inleted from the top and the process fluid is outleted from the bottom of the reactor vessel (by gravity).

[0095] The term "flushing operation" refers to the rinsing of the at least one growth body and / or reactor vessel. Purposefully, rinsing is carried out against gravity during flushing operation. In some embodiments, the cleaning fluid enters from below and the process fluid exits from above during flushing operation.

[0096] In some embodiments, the flow conditions are varied by pulsating flushing, i.e., repeatedly switching the flushing on and off.

[0097] In some embodiments, the rinsing is carried out in combination with the use of ultrasound in the range of 20 kHz to 500 kHz, preferably in the range of 20 kHz to 40 kHz. Advantageously, the use of ultrasound achieves the detachment of the sludge from the surface of the at least one growth body and / or the reactor vessel by cavitation.

[0098] In some embodiments, the flushing is carried out in combination with the use of ultrasound with an energy input per volume in the range of up to 5 kW / m³. 3 .

[0099] In some embodiments, the cleaning gas is at least an oxygen-free gas or gas mixture. In other embodiments, the cleaning gas is methane or a mixture comprising methane, carbon dioxide, and / or hydrogen. In further embodiments, the cleaning gas is an inert gas, in particular nitrogen.

[0100] In some embodiments, the cleaning gas is a gaseous substrate, in particular carbon dioxide and hydrogen or biogas and hydrogen. Advantageously, when gaseous substrate is introduced at the lower end of the reactor vessel during purging, the biosynthesis of methane is not interrupted and deteriorations in the quality of the product gas are avoided.

[0101] In some embodiments, purging is carried out in combination with the introduction of gas (cleaning gas) at the lower end of the reactor vessel, preferably at the bottom of the reactor vessel, and / or at the side surfaces of the reactor vessel. In other embodiments, the cleaning gas is introduced over a broad area at the lower end of the reactor vessel, preferably approximately in the middle of the bottom of the reactor vessel.

[0102] Kailuweit & Uhlemann | Patent Attorneys. In embodiments, gas a is introduced under overpressure. Advantageously, the pressure for introducing the gas is set based on the reactor's internal pressure, particularly due to the size of the reactor vessel and the process conditions. Advantageously, introducing gas at the lower end of the reactor vessel increases the turbulence at the growth medium, especially in the fixed bed.

[0103] In some embodiments, gas is introduced at the bottom of the reactor vessel, resulting in continuous bubbling. In other embodiments, oxygen-free gas is introduced at the bottom of the reactor vessel at a flow rate of approximately 3 m³. 3 / (m 2 h) up to 30 m 3 / (m 2 h).

[0104] In some embodiments, the purging of the at least one growth body and / or reactor vessel with cleaning fluid and cleaning gas is carried out through at least one inlet on the side surfaces of the reactor vessel. In other embodiments, the purging of the at least one growth body and / or reactor vessel with cleaning fluid and cleaning gas is carried out by the injection principle; that is, the generated hydrodynamic negative pressure allows both the cleaning gas to be supplied during purging and the gas to be drawn off from the gas dome, in particular product gas and / or unreacted reactant gas, to be drawn in and swirled as cleaning gas. Advantageously, this recirculation leads to improved gas quality, with the additional energy input from the injector also resulting in a better cleaning effect due to the improved swirling during purging.

[0105] In embodiments, after rinsing the at least one growth body with a cleaning fluid, the cleaning fluid is separated from the reactor container.

[0106] In embodiments, after rinsing the at least one growth body with a cleaning fluid, the cleaning fluid is separated at the upper end of the reactor vessel.

[0107] In some embodiments, the separated cleaning fluid is aerated. Advantageously, aeration significantly improves the settling behavior of the sludge.

[0108] In some embodiments, a solid-liquid separation of the cleaning liquid takes place after its initial separation. Advantageously, the separation of the solids from the cleaning liquid enables its recirculation. The separated solids from the cleaning liquid of a biogas plant can advantageously be used as...

[0109] Kailuweit & Uhlemann I Patent Attorneys Substrate or inoculation material are added to utilize their content of nutrients and degradable organic matter.

[0110] In some embodiments, the solid-liquid separation of the cleaning fluid is achieved through sedimentation, filtration, hydrocyclone separation and / or centrifugation.

[0111] In preferred embodiments, the solid-liquid separation of the cleaning fluid is carried out by decantation and filtration.

[0112] Another aspect of the invention relates to a device for the biosynthesis of methane using methanogenic microorganisms, comprising a reactor vessel:

[0113] i. at least one growth body,

[0114] ii. at least one inlet for a process fluid at the upper end of the reactor vessel,

[0115] iii. at least one inlet for a gaseous substrate,

[0116] iv. at least one outlet for venting the methane produced from the reactor vessel,

[0117] v. at least one inlet for a cleaning fluid at the lower end of the reactor vessel, and

[0118] vi. at least one outlet for the cleaning fluid.

[0119] The term "top end" refers to the top of the reactor vessel.

[0120] In some embodiments, the upper end of the reactor vessel serves as a lid.

[0121] In embodiments, the reactor vessel is a closed reactor vessel and the upper end of the reactor vessel has at least one handhole and / or at least one manhole and / or at least one flange.

[0122] The term "handhole" refers to an opening approximately the size of a hand.

[0123] The term "manhole" refers to an opening, as defined by DGUV Regulation 113-004 and TRGS 507, with a diameter between 500 mm and 800 mm. Ideally, a manhole should be large enough for an adult to pass through.

[0124] Kailuweit & Uhlemann I Patent Attorneys The term "flange" refers to an element for connecting two components, which in particular protrudes at right angles from the components to be connected.

[0125] The term "lower end" refers to the underside or the side of the reactor vessel facing the ground (earth's surface).

[0126] In some embodiments, the reactor vessel is a rotationally symmetrical body. In other embodiments, the reactor vessel is designed as an upright cylinder. A nearly cylindrical shape is also expediently included.

[0127] In embodiments, the diameter of the reactor is at least 30 cm, preferably in the range of 30 cm to 15 m, particularly preferably in the range of 30 cm to 5 m, especially in the range of 30 cm to 3 m.

[0128] In some embodiments, the reactor vessel has a volume in the range of 2 m³. 3 up to 3,000 m 3 on.

[0129] In some embodiments, the reactor vessel has a round bottom or a flat bottom.

[0130] In some embodiments, the reactor vessel is made of a corrosion-resistant material. Advantageously, the reactor vessel is thermally insulated to minimize heat loss.

[0131] In some embodiments, the reactor vessel consists of glass fiber reinforced plastic or steel, in particular unalloyed steel or stainless steel.

[0132] In some embodiments, the at least one growth body is arranged radially within the reactor vessel. The term "radial" is understood to mean extending in the direction of a radius of the reactor vessel, which is preferably designed as a vertically oriented cylinder.

[0133] In embodiments, the inlet for a process fluid at the upper end of the reactor vessel is a sprinkler device for sprinkling the at least one growth body with a process fluid.

[0134] In embodiments, the inlet for a process fluid is arranged centrally at the upper end of the reactor vessel, i.e. approximately in the middle of the top side of the reactor vessel.

[0135] Kailuweit & Uhlemann | Patent Attorneys. In embodiments, the inlet at the upper end of the reactor vessel comprises at least one distribution device, in particular a nozzle. Advantageously, the distribution device achieves a uniform distribution of the process fluid across the horizontal cross-section of the reactor vessel.

[0136] According to the invention, the device has at least one inlet for a gaseous substrate. In embodiments, the at least one inlet for a gaseous substrate is arranged at the upper end of the reactor vessel.

[0137] In some embodiments, the reactor vessel has at least one bottom. The term "bottom (also called step)" refers to an intermediate bottom in a reactor, which is permeable to gases and liquids but impermeable to the at least one growth medium, in particular the fixed bed packing.

[0138] In embodiments, the reactor vessel has at least two bottoms, thereby dividing the reactor vessel into at least three segments (“shots”).

[0139] In some embodiments, the base has a thickness ranging from 5 cm to 50 cm, preferably about 25 cm. In some embodiments, the base is vertically permeable to gases and liquids. In some embodiments, the base has slots, recesses, or holes.

[0140] In embodiments, the reactor vessel has at least one further inlet for gaseous substrate, wherein the at least one further inlet is arranged on at least one side surface of the reactor vessel, preferably in the area between the at least one bottom and the at least one growth body, in particular above the at least one growth body and below the top of the vessel.

[0141] In embodiments, the reactor vessel has at least one further inlet for gas, in particular cleaning gas, in particular gaseous substrate; wherein the at least one further inlet is arranged at the lower end of the reactor vessel and / or on at least one side surface of the reactor vessel, preferably in the area between the at least one bottom and the at least one growth body, in particular above the at least one growth body and below the top of the vessel.

[0142] In embodiments, the reactor vessel has at least one further inlet for cleaning fluid, wherein the at least one further inlet is located at at least one

[0143] Kailuweit & Uhlemann I Patent Attorneys side surface of the reactor vessel is arranged, preferably in the area of ​​the at least one growth body.

[0144] Advantageously, the inlet and outlet for the cleaning fluid are designed differently. According to the invention, the inlet for the cleaning fluid is arranged at the lower end of the reactor vessel. In embodiments, the outlet for the cleaning fluid is arranged at the lower end of the reactor vessel, at the upper end, and / or on at least one side surface of the reactor vessel. Advantageously, the cleaning fluid, along with the sludge suspended therein, is removed through the at least one outlet for the cleaning fluid. In embodiments, the reactor vessel has at least one outlet for the cleaning fluid at the upper end and / or on at least one side surface. In embodiments, the at least one outlet for the cleaning fluid is a shut-off connection, in particular a manual valve or solenoid valve with a discharge line.

[0145] In some embodiments, the outlet for the cleaning fluid has a sieve. Advantageously, the use of a sieve prevents the discharge of at least one growth body.

[0146] In embodiments, the reactor vessel further comprises at least one temperature control device, which is designed for heating and / or cooling.

[0147] In some embodiments, the reactor vessel further comprises at least one inlet for gas during purging, in particular for cleaning gas, at the lower end of the reactor vessel and / or on at least one side surface of the reactor vessel. In other embodiments, the reactor vessel further comprises at least one outlet for gas during purging, in particular for cleaning gas, product gas formed during purging, and reactant gas not reacted during purging, at the upper end of the reactor vessel. In other embodiments, the gas outlet is a gas dome. The term "gas dome (also gas hood)" refers to an access point to the reactor vessel with at least one seal, in particular a sealing collar, and a cover, which is used for collecting and / or controlled discharge of gas.

[0148] In embodiments, the reactor vessel further comprises at least one sensor selected from the group consisting of hydrogen probe, temperature sensor, pressure sensor, pH sensor, redox sensor and conductivity probe.

[0149] Kailuweit & Uhlemann | Patent Attorneys. In embodiments, the reactor vessel comprises at least one sensor, in particular a temperature sensor or pressure sensor, which is arranged axially in the reactor vessel. In embodiments, the reactor vessel comprises at least two sensors, in particular temperature sensors or pressure sensors, which are arranged axially in the reactor vessel in different planes.

[0150] In embodiments, the reactor vessel comprises at least one sensor, in particular a pH sensor, redox sensor or a conductivity probe, which is arranged in at least one inlet or outlet.

[0151] In embodiments, the reactor vessel further comprises at least one pressure relief valve and / or drain nozzle and / or at least one inspection opening.

[0152] For the realization of the invention, it is also advantageous to combine the aforementioned inventive configurations, embodiments and features of the claims.

[0153] The invention will now be explained in more detail using an exemplary embodiment. This exemplary embodiment will describe the invention without limiting its scope.

[0154] The invention is explained in more detail using drawings.

[0155] Fig. 1 shows a device according to the invention comprising a reactor vessel (1) having four bottoms (2) which support the growth bodies (3), in particular as a fixed bed (trickling bed), on which the microorganisms are immobilized as a biofilm, an inlet for the supply of a cleaning fluid at the lower end of the reactor (4), in particular by means of a bistable hydraulic overflow valve, an inlet for the supply of process fluid (5) at the upper end of the reactor vessel, in particular centrally on the top side of the reactor vessel (1), optionally further inlets on at least one side surface of the reactor vessel for cleaning fluid (6), further inlets on at least one side surface for gaseous substrate (14), an outlet for the cleaning fluid (7), in particular via three lockable outlets, an inlet for a gaseous substrate (8), an outlet for the discharge of formed methane (9),at least one further inlet for a cleaning gas (15) which can be used in combination with the cleaning liquid, in particular a gaseous substrate, an outlet (10) for gas, in particular cleaning gas, and of the,

[0156] Kailuweit & Uhlemann I Patent Attorneys during the purging process unreacted reactant gas, in particular designed as a gas dome, the fill level during the purging process (11), the fill level during normal operation (steps b) to d)) (12) and an outlet for the process liquid (13) at the lower end of the reactor vessel (1).

[0157] For the inventive process for the biosynthesis of methane, the device according to Fig. is used.

[0158] 1 inoculated with methanogenic microorganisms and process fluid and a gaseous substrate (reactant gas mixture) comprising carbon dioxide and hydrogen are introduced.

[0159] The device according to the invention, as shown in Fig. 1, for the biosynthesis of methane using methanogenic microorganisms comprises a reactor vessel (1) in the form of a slender cylinder with a diameter of 1 m, made of a corrosion-resistant material, in particular stainless steel, or having an internal corrosion-resistant surface coating. The reactor is divided into five segments (“trays”) by four trays (2). These trays (2) support the bed of growth media (3), in particular as a fixed bed, on which the microorganisms are immobilized as a biofilm. The highest bioreaction rate takes place in the uppermost level (segment). The trays (2) optionally serve as heat exchangers for the removal of the heat of reaction due to their internal structure, and the trays have a thickness of 25 cm.The bottoms (2) are vertically permeable to the reaction gases and also to liquids, in particular the process fluid and the cleaning fluid. The process fluid is a free-flowing liquid (aqueous nutrient solution) that, during normal operation (steps b) to d)), supplies the biofilm of the methanogenic microorganisms with water and nutrients. The process fluid is supplied through an inlet (5) at the upper end of the reactor vessel during normal operation, in particular centrally or approximately at the midpoint of the upper end / top of the reactor vessel (5), and the outlet for the process fluid is located at the bottom (13). In one embodiment, the inlet (5) at the upper end of the reactor vessel comprises at least one distribution device, in particular a nozzle, for uniformly distributing the process fluid over the horizontal cross-section of the reactor vessel.Another liquid is the cleaning fluid, which is used for flushing (desludge removal). The cleaning fluid is supplied through an inlet at the lower end of the reactor (4) during flushing, in particular through a bistable hydraulic overflow valve. Flushing can be carried out segment by segment for total or partial flushing from the segment of the reactor vessel below, with the cleaning fluid and the suspended sludge being discharged via at least one outlet (7), in particular via three lockable outlets. The cleaning fluid can be combined with a cleaning gas.

[0160] Kailuweit & Uhlemann I Patent Attorneys, wherein the cleaning gas is introduced via inlets at the lower end of the reactor vessel and, if necessary, on the side surfaces (15) and discharged via an outlet at the upper end of the reactor vessel (10). The fill level during the purging process (11) indicates that the entire reactor vessel has been purged. After the cleaning fluid has been removed, the fill level during normal operation (12) is reached.

[0161] To prevent the discharge of the at least one growth body (3), a sieve is provided in front of the outlet for the cleaning fluid (7). During the rinsing process, the trays (2) also serve to fix the at least one growth body (3). This is particularly advantageous during cleaning and prevents the discharge of the at least one growth body (3), especially its entry into the reactor segment above or into the outlet for the cleaning fluid (7).

[0162] The reactor vessel also has an inlet at the upper end for a gaseous substrate (8) and an outlet (10) for gas during purging operation, including cleaning gas and reactant gas not reacted during the purging process, in particular designed as a gas dome.

[0163] At the bottom of the reactor, an outlet for venting generated methane (9) and an outlet for process fluid (13) during normal operation, an inlet for cleaning fluid (4), and optionally an inlet for gas introduction during purging are arranged. For purging, three inlets are optionally arranged on at least one side of the reactor vessel for an intensive, tangentially flowing fine jet (6) of cleaning fluid in the respective segments, which promotes the turbulence of the biofilm during cleaning.

[0164] Additionally, sensors for temperature, pressure, pH value, or other physical or chemical parameters can be arranged along the length of the reactor. Furthermore, safety devices such as pressure relief valves, drain plugs, and inspection openings can also be installed. The entire reactor is well thermally insulated to minimize heat loss.

[0165] In another embodiment, the rinsing of the growth bodies and the reactor vessel is carried out by means of cleaning fluid and cleaning gas through four inlets on the side surfaces of the reactor vessel; in particular, a tangentially flowing fine jet of cleaning fluid (6) and cleaning gas is combined in the respective segments.

[0166] Kailuweit & Uhlemann | Patent Attorneys. In one embodiment, the purging of the growth media and the reactor vessel with cleaning fluid and cleaning gas is carried out using the injection principle. This means that the generated hydrodynamic negative pressure allows both the cleaning gas supplied during purging and the gas drawn off from the gas dome, in particular product gas and / or unreacted reactant gas, to be drawn in and swirled as cleaning gas. Advantageously, this recirculation leads to a higher conversion rate and improved gas quality, while the additional energy input from the injector also results in a better cleaning effect due to the enhanced swirling during purging.

[0167] Kailuweit & Uhlemann | Patent Attorneys Reference number

[0168] 1 reactor vessel

[0169] 2 floors, optionally as heat exchangers

[0170] 3 At least one growth medium, optionally as a fixed bed 4 Inlet for cleaning fluid

[0171] 5 Inlet for process fluid

[0172] 6 additional inlets for cleaning fluid

[0173] 7 Outlet for cleaning fluid

[0174] 8 Inlet for gaseous substrate

[0175] 9 Outlet for venting formed methane

[0176] 10 Outlet for cleaning gas

[0177] 11 Fill level during flushing

[0178] 12. Fill level during steps b) to d)

[0179] 13 Outlet for process fluid

[0180] 14 additional inlets for gaseous substrate

[0181] 15 Inlet for cleaning gas

[0182] Kailuweit & Uhlemann I patent attorneys

Claims

Patent claims 1. Method for the biosynthesis of methane using methanogenic microorganisms, comprising the steps: a) Inoculating a surface of at least one growth body (3) with methanogenic microorganisms in a reactor vessel (1), b) Introducing a process fluid comprising nutrients and water at the top of the reactor vessel (1), wherein the surface of the at least one growth body (3) containing the methanogenic microorganisms comes into contact with the process fluid, c) Introducing a gaseous substrate comprising carbon monoxide or carbon dioxide and hydrogen into the reactor vessel, wherein the surface of the at least one growth body (3) containing the methanogenic microorganisms comes into contact with the gaseous substrate, d) Discharge of the methane produced from the reactor vessel (1), characterized in that at least one rinsing of the at least one growth body (3) and / or reactor container (1) is carried out by a cleaning fluid with a flow in the opposite direction to gravity with an empty tube velocity in the range of 5 m / h to 200 m / h before, during and / or after step d).

2. The method according to claim 1, characterized in that the at least one growth body (3) is a fixed bed packing or a heat exchanger.

3. The method according to claim 2, characterized in that the fixed bed fill is formed from plastic particles or wood chips.

4. The method according to one of claims 1 to 3, characterized in that the inoculation of a surface with methanogenic microorganisms in step a) is carried out by the simultaneous application of accompanying organisms which form adhesive proteins.

5. The method according to one of claims 1 to 4, characterized in that the introduction of the process fluid in step b), the introduction of a gaseous substrate in step c) and / or the discharge of the formed methane in step d) is carried out continuously. Kailuweit & Uhlemann I Patent Attorneys6. The method according to one of claims 1 to 5, characterized in that the introduction of the process fluid in step b) is carried out as a continuous recirculation of a process fluid.

7. The method according to any one of claims 1 to 6, characterized in that the cleaning fluid is water or an aqueous solution.

8. The method according to one of claims 1 to 7, characterized in that the rinsing of the at least one growth body (3) and / or reactor vessel (1) takes place after a pressure loss of at least 10% with respect to the initial pressure inside the reactor vessel (1).

9. The method according to one of claims 1 to 8, characterized in that the rinsing of the at least one growth body (3) and / or reactor vessel (1) is carried out by a cleaning fluid with a flow in the opposite direction to gravity at an empty tube velocity in the range of 10 m / h to 70 m / h.

10. The method according to any one of claims 1 to 9, characterized in that the rinsing is carried out in combination with a variation of the flow conditions of the cleaning fluid, a use of ultrasound and / or by introducing oxygen-free gas at the lower end of the reactor vessel (1).

11. The method according to one of claims 1 to 10, characterized in that after rinsing the at least one growth body (3) by a cleaning fluid, the cleaning fluid is separated at the upper end of the reactor vessel (1) and the cleaning fluid is solid-liquid separated.

12. Device for the biosynthesis of methane using methanogenic microorganisms comprising a reactor vessel (1): i. at least one growth body (3), ii. at least one inlet for a process fluid (5) at the upper end of the reactor vessel (1), iii. at least one inlet for a gaseous substrate (8), iv. at least one outlet for venting the methane (9) produced from the reactor vessel (1), Kailuweit & Uhlemann I Patent Attorneys at least one inlet for a cleaning fluid (4) at the lower end of the reactor vessel (1), and vi. at least one outlet for the cleaning fluid (7).

13. The device according to claim 12, characterized in that the inlet for a process fluid (5) is arranged at the upper end of the reactor vessel (1) and is designed as a sprinkler device for sprinkling the at least one growth body (3) with a process fluid.

14. The device according to claim 12 or 13, characterized in that the at least one outlet for the cleaning fluid (7) is arranged at the upper end and / or on at least one side surface of the reactor vessel.

15. The device according to one of claims 12 to 14, characterized in that the reactor vessel (1) has at least one further inlet for the cleaning fluid (6), wherein the at least one further inlet (6) is arranged on at least one side surface of the reactor vessel. Kailuweit & Uhlemann I patent attorneys

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