KR-102964497-B1 - Methanation using a turbocharger

KR102964497B1KR 102964497 B1KR102964497 B1KR 102964497B1KR-102964497-B1

Abstract

The present invention relates to an improved methanation process, wherein energy released during the methanation process is used to drive a turbocharger to drive and/or maintain the process. The present invention also relates to a system for producing methane-enriched gas and electricity from hydrogen and carbon-containing starter materials, comprising at least one methanation reactor and at least one turbocharger.

Inventors

헤르만, 스테판
피셔, 펠릭스
스플리트호프, 하트무트

Assignees

테크니쉐 우니베르지테트 뮌헨

Dates

Publication Date: 20260512
Application Date: 20210928
Priority Date: 20201013

Claims (20)

A method for producing methane-enriched gas from a hydrogen and carbon-containing starting material in a system comprising at least one single-stage or multi-stage methanation process, a) each of at least one methanation reactor (1) for a single-stage or multi-stage methanation method, comprising an inlet for introducing a feed gas containing hydrogen and carbon-containing starting materials or methane-enriched gas from a previous methanation stage and an outlet for a methane-enriched product gas; A continuous gas line having an inlet (6) for introducing hydrogen and carbon-containing starter materials, and an outlet (7) for removing methane-enriched gas from the system; At least one turbocharger (2) comprising a turbine (4) mechanically connected by a compressor (3) and a common shaft (5) (wherein the methanation reactor(s) and at least one turbocharger are connected via a continuous gas line); The above at least one compressor is connected to a continuous gas line and is positioned upstream, between, or downstream of the methanation reactor in a section of the continuous gas line that defines the path from the introduction of the starting material to the removal of the methane-enriched gas; b) a step of introducing hydrogen and carbon-containing starter materials into the inlet of a continuous gas line; c) a step of generating methane-enriched gas in the above methanation reactor(s); and d) A method comprising the step of increasing the system pressure in a continuous gas line through at least one compressor using the energy released during the above methanation method.
A method according to claim 1, further comprising an additional step between step b) and step c) of directly injecting water or steam into at least one methanation reactor or directly injecting it upstream of a continuous gas line at an inlet for introducing a supply gas into at least one methanation reactor.
A method according to claim 1, further comprising an additional step between step b) and step c) of directly injecting water or steam into at least one methanation reactor or directly injecting it upstream of a continuous gas line of a turbocharger turbine.
A method according to claim 1, wherein a thermal power plant having a working medium performed in the above-mentioned a) stage thermal power plant line is provided, said thermal power plant is coupled to at least one methanation reactor or gas stream derived through at least one heat exchanger (8), said thermal power plant generates power, and optionally the thermal power plant is a steam turbine (16) having steam (15) in a line of a steam turbine cycle.
A method according to claim 1 or 4, wherein the turbine of at least one turbocharger is connected to a continuous gas line or, if present, to one of the thermal power plant lines.
A method according to claim 1 or 2, further comprising step e) of removing methane-enriched gas from the system at the outlet of the continuous gas line.
A method according to claim 1 or 2, characterized in that the carbon-containing starting material is CO2 .
A method according to claim 1 or 2, characterized in that the carbon-containing starting material is CO.
A method according to claim 1 or 2, characterized in that the hydrogen and carbon-containing starting material is provided at atmospheric pressure.
A method according to claim 1 or 2, characterized in that the pressure at the outlet of the continuous gas line is higher than the pressure at the inlet of the continuous gas line.
A method according to claim 1 or 2, characterized by additionally including a step of preheating a methanation reactor prior to step b) of claim 1.
A method according to claim 1 or 2, characterized by further including a step of providing external energy to a compressor to facilitate the initial compression of a hydrogen and carbon-containing starter material prior to the methanation method.
A method according to claim 1 or 2, wherein the one or more compressors increase the pressure within the continuous gas line at a position located between the inlet of the continuous gas line and the inlet of the first methanation reactor.
A method according to claim 1 or 2, wherein the one or more compressors increase the pressure within the continuous gas line at a position located between the outlet of the methanation reactor and the outlet of the continuous gas line.
A method according to claim 1 or 2, characterized in that the turbine is located upstream of one or more compressors.
A method according to claim 1 or 2, wherein a plurality of turbochargers are used, and two, three or more turbochargers are used; and intermediate cooling or intermediate heating of a continuous gas line is performed through a heat exchanger (8).
A method according to claim 1 or 2, characterized in that at least one single-stage methanation method is adiabatic or at least one stage of a multi-stage methanation method is adiabatic.
A method according to claim 2 or 3, wherein at least one single-stage methanation method is isothermal or at least one multi-stage methanation method is isothermal, and in the isothermal method, the temperature in the methanation reactor is controlled by a thermal power plant.
A method according to claim 1 or 4, wherein the turbine reduces the pressure of the gas coming out of the methanation reactor; and wherein the turbine, if present, reduces the pressure of the working medium performed in the thermal power plant line used to control the temperature of the methanation reactor.
In claim 4, the heat exchanger (8) is a heat exchanger, and the heat exchanger transfers heat from the gas exiting the turbine to the hydrogen and carbon-containing starter material, and then transfers heat before the hydrogen and carbon-containing starter material enters the methanation reactor.

Description

Methanation using a turbocharger The present invention relates to an improved methanation process, wherein energy released during the methanation process is used to drive a turbocharger to drive and/or maintain the process. The present invention also relates to a system for producing methane-enriched gas and optionally electricity from hydrogen and carbon-containing starters, comprising at least one methanation reactor and at least one turbocharger. Methanation is the conversion of carbon monoxide (CO) and/or carbon dioxide ( CO₂ ) into methane ( CH₄ ) through hydrogenation. This process was discovered in the early 20th century. Exemplary reactions describing the methanation of carbon monoxide and carbon dioxide, respectively, are as follows: CO + 3H₂ → CH₄ + H₂O 4H₂ + CO₂ → CH₄ + 2H₂O The above methanation reaction is classified as an exothermic reaction. Examples of possible starting materials include CO₂ from biogas plants and H₂ from high-temperature electrolysis plants. An example of a methanation process of the prior art is the Topsøe Recycle Energy-efficient Methanation Process (TREMP ™ ) by Haldor Topsøe. The TREMP ™ process can operate at high temperatures of up to 973°C due to the MCR-2X methanation catalyst used in the process. This catalyst can recover reaction heat in the form of high-pressure superheated steam and ensures energy savings through a low recycling rate. CO₂ methanation takes place in adiabatic fixed-bed reactors. The exothermic reaction causes a high temperature rise. The methane-enriched gas, a reaction product generated in this process, is partially recycled to control the temperature rise in the methanation reactor. Interest in alternative natural gas has increased over the past decade. Efforts regarding this technology have been restarted, and knowledge gained over the years has been used to improve proven technologies and catalysts. A demonstration plant (Westfield Coal Gasification Plant) has been constructed in Scotland and is producing 2.46 million Nm³ /h of SNG from coal. The methanation unit used in this plant consists of a fixed-bed reactor with a gas recycling function. Further development by the UK Gas Corporation was the HICOM process, which directly produces methane-rich gas from purified gasifier production gas by reacting it with steam through a catalyst; the temperature rise is controlled by high-temperature gas recycling and split stream operation. In Germany, Linde developed an indirect heat exchange type isothermal fixed-bed reactor. The reactor itself can generate steam from the heat of the exothermic methanation reaction. A portion of the steam is added to the synthesis gas mixture to minimize the risk of carbon deposition before being fed to the isothermal and adiabatic methanation reactor. All processes described above utilize fixed-bed reactors that recycle the cooled product gas or add steam. This is necessary to efficiently dissipate the high reaction enthalpy (about 20% of the feed gas calorific value) and, if necessary, to use it profitably, particularly for steam generation and superheated steam generation. On the other hand, in small-scale systems, single-stage, nearly isothermal reactor arrays combined with thermal power plants are often used. The heat generated from the methanation process is used to heat the working medium in the thermal power plant. Typically, the working medium is water, and a boiling water reactor setup is used to control the reaction temperature of the methanation reactor. Alternative working media include thermal oil and molten salt. The water is heated to generate steam. The steam is then expanded, mostly in a steam turbine, to produce electricity. The power-to-gas process, which stores energy by synthesizing gas using surplus electricity, is the most promising technology for seasonal energy storage. The primary storage media are hydrogen and methane. Methane has the advantage of being able to utilize existing infrastructure (gas pipelines, natural gas tanks) compared to hydrogen. Interest in this technology is high, with as many as 128 research and demonstration plants for the power-to-gas process operating in Europe as of 2018. To provide an economically viable and technically feasible methanation process, the produced methane must meet several requirements. The methane produced in the methanation process must have high purity, as methane of low purity must not be supplied to the natural gas network. Furthermore, the methane must be pressurized before being supplied to the natural gas network. Therefore, a satisfactory methanation process must produce high-purity pressurized methane. However, possible sources of starting materials for the methanation process are biogas plants supplying CO2 and high-temperature electrolysis plants supplying H2 . These plants generally supply products at low pressure. Therefore, some conventional methanation plants operate at low pressure and produce methane of low purity. This methane must