CN-121986083-A - Methanation device, methanation method, hydrocarbon direct decomposition device, and hydrocarbon direct decomposition method

CN121986083ACN 121986083 ACN121986083 ACN 121986083ACN-121986083-A

Abstract

A methanation device for removing saturated hydrocarbons from a raw gas containing methane and saturated hydrocarbons by converting saturated hydrocarbons having two or more carbon atoms into methane by reacting them with hydrogen, the methanation device comprising at least two catalyst layers each comprising a catalyst for methanation and provided at a distance from each other in the flow direction of a mixed gas containing the raw gas and a hydrogen-containing gas, a hydrogen supply line for supplying a hydrogen-containing gas to the upstream side of the catalyst layer on the most upstream side in the flow direction of the mixed gas, a raw gas supply line for supplying a raw gas to each of the two catalyst layers on the upstream side of the catalyst layer on the most upstream side in the flow direction of the mixed gas and the adjacent catalyst layers in the flow direction of the mixed gas, and a cooler provided between the two catalyst layers adjacent in the flow direction of the mixed gas and cooling the mixed gas flowing out of the catalyst layers on the upstream side in the flow direction of the mixed gas among the adjacent two catalyst layers.

Inventors

YE DAOFAN
Kubota Chongshi
An Hongxian
OMOTO SETSUO

Assignees

三菱重工业株式会社

Dates

Publication Date: 20260505
Application Date: 20241122
Priority Date: 20231227

Claims (12)

1. A methanation device for converting saturated hydrocarbons having two or more carbon atoms into methane by reacting the saturated hydrocarbons with hydrogen, the saturated hydrocarbons being removed from a raw material gas containing methane and the saturated hydrocarbons, the methanation device comprising: at least two catalyst layers each composed of the methanation catalyst and provided at an interval in the flow direction of a mixed gas containing the raw material gas and a hydrogen-containing gas; a hydrogen supply line for supplying the hydrogen-containing gas to an upstream side of the most upstream side catalyst layer in the flow direction of the mixed gas; A raw material gas supply line for supplying the raw material gas to each of two catalyst layers upstream of the most upstream catalyst layer in the flow direction of the mixed gas and adjacent to each other in the flow direction of the mixed gas, and And a cooler provided between two adjacent catalyst layers in the flow direction of the mixed gas, for cooling the mixed gas flowing out from the catalyst layer on the upstream side in the flow direction of the mixed gas among the two adjacent catalyst layers.
2. Methanation apparatus according to claim 1, wherein, The catalyst layers on the downstream side in the flow direction of the mixed gas are more in terms of the amounts of the catalysts constituting the at least two catalyst layers, respectively.
3. Methanation apparatus according to claim 1 or 2, wherein, The catalyst is a supported catalyst in which nickel, iron, cobalt or a noble metal element is supported on alumina.
4. A device for directly decomposing hydrocarbon, which comprises a main body, the hydrocarbon direct decomposition device comprises: Methanation device according to claim 1 or 2; a reactor containing a catalyst for the direct decomposition reaction of hydrocarbons, and And a treated gas supply line for supplying a treated gas, which is a gas flowing out of the methanation device, to the reactor.
5. The apparatus for directly decomposing hydrocarbons according to claim 4, wherein the apparatus comprises: A product gas flow line through which a product gas containing hydrogen generated by direct decomposition of hydrocarbons in the reactor flows after flowing out of the reactor, and A hydrogen recycle line connecting the product gas flow line with the hydrogen supply line.
6. A methanation process for converting a saturated hydrocarbon having two or more carbon atoms into methane by reacting the saturated hydrocarbon with hydrogen, the saturated hydrocarbon being removed from a feed gas comprising methane and the saturated hydrocarbon, the methanation process comprising the steps of: Flowing a hydrogen-containing gas to a catalyst layer on an upstream-most side of at least two catalyst layers, the at least two catalyst layers being composed of the methanation catalyst and being provided at an interval in a flow direction of a mixed gas including the raw material gas and the hydrogen-containing gas; Flowing a part of the raw material gas to a catalyst layer on the most upstream side in the flow direction of the mixed gas; supplying the remaining portion of the raw material gas to two catalyst layers adjacent in the flow direction of the mixed gas; cooling the mixed gas flowing out of the catalyst layer on the upstream side of the adjacent two catalyst layers, and And flowing the cooled mixed gas and the raw material gas supplied between two adjacent catalyst layers in the flow direction of the mixed gas to a catalyst layer on a downstream side of the two adjacent catalyst layers.
7. The methanation process according to claim 6, wherein, The supply amount of the hydrogen-containing gas is adjusted so that the concentration ratio of hydrogen to the saturated hydrocarbon in the mixed gas becomes 1 or more.
8. The methanation process according to claim 6 or 7, wherein, The hydrogen-containing gas comprises hydrogen and components that do not contribute to the methanation.
9. The methanation process according to claim 6 or 7, wherein it comprises the steps of: Detecting a decrease in the activity of the methanation, and When the decrease in activity is detected, the supply amount of the hydrogen-containing gas is increased.
10. The methanation process according to claim 6 or 7, wherein, The raw material gas is natural gas, compressed natural gas, city gas, liquefied petroleum gas or naphtha.
11. A process for the direct decomposition of hydrocarbons, the process comprising the steps of: converting the saturated hydrocarbons in the feed gas to methane by a methanation process according to claim 6 or 7; The gas after converting the saturated hydrocarbon into methane, i.e., the treated gas, is brought into contact with a catalyst for the direct decomposition reaction of hydrocarbons, whereby methane in the treated gas is directly decomposed into hydrogen and carbon.
12. The method for the direct decomposition of hydrocarbons according to claim 11, wherein, At least a part of a product gas containing hydrogen generated by directly decomposing methane in the treated gas into hydrogen and carbon is used as at least a part of the hydrogen-containing gas supplied to a catalyst layer on the most upstream side of at least two catalyst layers provided at a distance in the flow direction of the mixed gas.

Description

Methanation device, methanation method, hydrocarbon direct decomposition device, and hydrocarbon direct decomposition method Technical Field The present disclosure relates to a methanation apparatus, a methanation method, a direct hydrocarbon decomposition apparatus, and a direct hydrocarbon decomposition method. The present application claims priority based on japanese patent application No. 2023-220345 filed by the japanese patent office on 12/27 of 2023, the contents of which are incorporated herein by reference. Background At present, the production of various energy sources is largely dependent on fossil fuels such as petroleum, coal, and natural gas, but from the viewpoint of protecting the global environment, an increase in the amount of carbon dioxide released by the combustion of fossil fuels is regarded as a problem. In paris agreement agreed in 2015, in order to cope with the climate change problem, it is required to reduce the amount of carbon dioxide emissions, but in a thermal power plant or the like, it is an important problem to reduce the amount of carbon dioxide emissions generated by the combustion of fossil fuel. While processes for separating and recovering carbon dioxide discharged have been actively studied, a technology for producing energy without discharging carbon dioxide by using alternative fuels to fossil fuels has been studied. Therefore, as an alternative fuel to fossil fuels, hydrogen as a clean fuel that does not emit carbon dioxide by combustion is attracting attention. Hydrogen can be produced, for example, by steam reforming methane contained in natural gas. However, in this production method, carbon monoxide is produced as a by-product, and carbon monoxide is finally oxidized and discharged as carbon dioxide. On the other hand, as a method for producing hydrogen from water without using fossil fuel, a water electrolysis method, a photocatalytic method, or the like has been studied, but these methods require a large amount of energy and are economically problematic. In this regard, a method of directly decomposing hydrocarbons to produce hydrogen and carbon has been developed. The direct decomposition of hydrocarbons is characterized in that a hydrogen fuel is obtained without discharging carbon dioxide, and carbon as a by-product is solid, and therefore, the carbon itself can be easily immobilized and can be effectively used for a wide range of applications such as electrode materials, tire materials, building materials, and the like. Heretofore, a method has been developed in which a hydrocarbon is directly decomposed into hydrogen and carbon by bringing a supported catalyst into contact with a hydrocarbon gas, but carbon, which is a product of the direct decomposition reaction of the hydrocarbon, adheres to the catalyst, thereby causing a problem that the catalyst activity is reduced in a short period of time. In contrast, the applicant of the present disclosure has developed a method of directly decomposing hydrocarbons into carbon and hydrogen using a catalyst that is an unsupported catalyst that is an aggregate of a plurality of particles made of iron, as described in patent document 1. According to this method, it was examined that even if carbon, which is a product of a direct decomposition reaction of hydrocarbon, adheres to a catalyst, the activity is maintained by showing a new active site, and thus the activity of the reaction can be maintained for a long period of time. When natural gas is used as a raw material gas for the direct decomposition reaction of hydrocarbons, for example, saturated hydrocarbons having two or more carbon atoms (hereinafter referred to as "saturated hydrocarbons c2+") such as ethane, propane, butane, and the like are contained in the natural gas in addition to methane, and saturated hydrocarbons c2+ are more reactive than methane, so that at the temperature at which the direct decomposition reaction of methane occurs, side reactions such as thermal decomposition of saturated hydrocarbons c2+ and polymerization may occur, for example, clogging of piping may occur. In the case where a feed gas containing saturated hydrocarbons c2+ is used as a feed for the direct decomposition reaction of hydrocarbons, in order to suppress such risk, it is necessary to remove saturated hydrocarbons c2+ from the feed gas. When ethane, propane, and butane are used as examples of the saturated hydrocarbons c2+, the saturated hydrocarbons c2+ may be converted into methane by reacting the saturated hydrocarbons c2+ with hydrogen as shown in the following equations (1) to (3), and removed from the raw material gas. In general, the synthesis of methane from hydrogen and carbon dioxide is often referred to as methanation, but in the present disclosure, the reaction in which saturated hydrocarbon c2+ is converted into methane by the reaction of saturated hydrocarbon c2+ with hydrogen as shown in equations (1) to (3) is defined as "methanation". C2H6+H2→2CH4(1)