Method and plant for the production of methane-containing synthetic natural gas streams
The method and plant address catalyst overheating and external energy needs by using a heat transfer device to regenerate the absorption medium, enabling efficient methane production with high-purity CO2 byproduct and cost reduction.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KANADEVIA INOVA AG
- Filing Date
- 2024-03-27
- Publication Date
- 2026-04-14
AI Technical Summary
Existing methanation reactors face challenges in maintaining constant reaction conditions and preventing catalyst damage due to excess exothermic reaction energy, while also requiring external energy for absorption medium regeneration and efficient production of methane-containing synthesis gas.
A method and plant that utilize a heat transfer device with water as a medium to transfer heat from the methanation reactor to a separation unit, regenerating the absorption medium and stabilizing the reaction, using the exothermic heat to prevent catalyst damage and reduce production costs.
The method and plant efficiently produce methane-containing synthesis gas with high-purity CO2 byproduct, avoiding catalyst damage and reducing production costs through internal heat utilization and simplified process design.
Smart Images
Figure 2026511584000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method and a plant for the production of methane-containing synthesis gas according to the preambles of claims 1 and 7.
Background Art
[0002] The methanation reaction is a catalytic reaction of hydrogen (H2) with carbon monoxide (CO) and / or carbon dioxide (CO2), and produces a methane-containing gas. This methane-containing gas, also called synthesis gas, can be used as an alternative gas to natural gas. In regions where natural gas is scarce, other energy sources such as coal or petroleum coke can be partially oxidized in a gasification process to produce a gas containing hydrogen and CO. Such a gas containing hydrogen and CO is also called feed gas. Thereafter, synthesis gas ("syngas") can be produced in a methanation process using the feed gas.
[0003] The methanation process includes the following reactions in the presence of a suitable methanation catalyst. (I) CO + 3H2→ CH4+ H2O (-206 kJ / mol) (II) CO2+ 4H2→ CH4+ 2H2O (-164 kJ / mol)
[0004] The water formed between reactions (I) and (II) can then react in-situ with CO in the water-gas shift reaction (III), depending on the catalyst, temperature and concentration present. (III) CO + H2O → CO2+ H2(-41 kJ / mol)
[0005] All three reactions (I), (II) and (III) are exothermic.
[0006] Various systems for performing the above methanation process have been proposed conventionally.
[0007] International Publication No. 2020 / 069974 discloses a fixed-bed apparatus in the form of an insert for a reactor for catalytic methane production of a mixed gas containing hydrogen and carbon dioxide.
[0008] The UK Patent Application Publication No. 2018818 discloses a process for preparing methane-rich gas in at least one adiabatically operating methane reactor by transforming a combination of a preheated synthesis gas stream and a recirculated stream from a methane reactor. The combined preheated synthesis gas stream and recirculated stream pass through a layer of shift catalyst immediately before passing through the methane catalyst.
[0009] U.S. Patent Application Publication No. 2010 / 0162626 discloses an adiabatic reactor, a process and system for producing methane-rich gas in such an adiabatic reactor. The adiabatic reactor comprises a first inlet and a first outlet defining a first flow path between the first inlet and the first outlet, and a second inlet and a second outlet defining a second flow path between the second inlet and the second outlet. The first and second flow paths are oriented in opposite directions to each other, are thermally connected via a partition, and each contains a catalyst. The described process uses the adiabatic reactor to produce a methane-enriched gas from a feed gas containing CO and hydrogen. The described system comprises two or more adiabatic reactors connected to each other.
[0010] One problem in the field of methanation reactors is that, in order to maintain constant reaction conditions, the methanation reactor must remove excess exothermic reaction energy (heat) to prevent overheating, which can damage the catalyst inside the reactor. [Overview of the Initiative] [Problems that the invention aims to solve]
[0011] The problem that this invention aims to solve is to provide a method and plant for producing methane-containing synthesis gas and high-purity CO2 as a by-product in an energy-efficient and economical manner. [Means for solving the problem]
[0012] This problem is solved by the method for producing methane-containing synthesis gas described in claim 1 and the plant for producing methane-containing synthesis gas described in claim 7.
[0013] A method for producing a methane-containing synthesis gas stream is provided according to the present invention. The method comprises the following steps: In the first step a), a feed gas is provided containing CO and / or CO2 as a carbon source and H2 as a first hydrogen source. In the second step b), the temperature of the feed gas from the first step is adjusted to a temperature T1 of 150°C to 300°C. In the third step c), the feed gas from the second step is reacted in a methanation reactor to produce heat and a raw synthesis gas containing methane, CO2, and generally water. The methanation reactor contains a catalyst containing a compound selected from the group consisting of Ni, Co, Fe, Pd, Pt, Ru, Rh, and combinations thereof. In the fourth step d), the raw synthesis gas is transferred to a separation unit containing an absorption medium. Here, the separation unit is an amine scrubber, and the absorption medium is an amine solution. In the fifth step e), the raw synthesis gas is separated into a methane-enriched synthesis gas stream and a CO2-saturated absorption medium. Finally, in the sixth step f), the heat generated in the methane reactor is used to increase the temperature of the CO2 saturated absorption medium, thereby regenerating the CO2 saturated absorption medium and producing a regenerated absorption medium with reduced CO2 content and an exhaust gas flow containing CO2.
[0014] One important feature of the present invention is that the heat generated in the methanation reactor is transferred to a separation unit with the help of a heat transfer device comprising a heat exchanger and water as a heat transfer medium. Utilizing the heat of the exothermic methanation reaction to regenerate the absorption medium offers the advantages of stabilizing the methanation reaction, avoiding catalyst damage due to overheating, enabling efficient production of crude synthesis gas (which is lost at excessively high temperatures), and reducing production costs because external energy is not required to regenerate the absorption medium.
[0015] Another advantage lies in the use of the heat transfer device of the present invention for heat transfer from the methanation reactor to the separation unit. The use of the heat transfer device of the present invention allows these two components to be positioned apart from each other, in contrast to the process in which the absorption medium is transported through the methanation reactor for regeneration.
[0016] As described above, the heat transfer medium in the method of the present invention is water. However, it is obvious to those skilled in the art that the heat generated in the methane reactor can convert the water in the heat transfer medium into steam. Therefore, the use of steam as the heat transfer medium is also included. However, it is important that the heat transfer medium is not in direct contact with the reaction. One advantage of using water as the heat transfer medium is that a natural convection system of water / steam can be used, thereby eliminating the need for a pump to transfer the water / steam from the methane reactor to the separation unit.
[0017] Crude synthesis gas typically contains at least 30% by volume of methane and up to 70% by volume of CO2. Since CO2 is the main component of crude synthesis gas, exhaust gas streams containing high-purity CO can be used for various applications such as dry ice production and beverage carbonation.
[0018] In a preferred embodiment of the present invention, water is used as a secondary hydrogen source. Preferably, the water in the feed gas turns into steam after the temperature rises in step b). This supply of steam has three main advantages.
[0019] Firstly, it can be used to remove carbon deposits on the catalyst by a steam reforming reaction according to the following reaction (IV). (IV) H2O + C → CO + H2
[0020] This process regenerates the catalyst, making it possible to obtain sufficient catalytic activity over a long period without maintenance work.
[0021] Secondly, the supply of water vapor significantly reduces the hydrogen concentration and increases the CO2 concentration in the crude synthesis gas because CO is converted to CO2 according to the water-gas shift reaction (III) described above. This is beneficial because post-treatment of crude synthesis gas with a high hydrogen concentration is far more difficult than that of crude synthesis gas with a high CO2 concentration. In particular, hydrogen has a boiling point of -252.9°C, making separation by liquefaction impossible, which complicates the separation of hydrogen from crude synthesis gas. Furthermore, hydrogen is a reactive substance that makes regeneration difficult. Currently, rational separation of hydrogen from crude synthesis gas relies on the aid of membrane or pressure swing absorption, which increases the cost of separation. Therefore, the production of crude synthesis gas with a minimum amount of hydrogen is one clear advantage of the method of the present invention.
[0022] A third advantage is that steam can be used as an internal cooling system within the methanation reactor because it has a high capacity to buffer the heat (thermal energy) generated by the exothermic methanation reaction. This is important because excessively high temperature peaks can damage the catalyst.
[0023] Preferably, the heat transfer apparatus comprises a first loop connecting the methanation reactor and the heat exchanger, and a second loop connecting the separation unit and the heat exchanger. The purity requirement for the heat transfer medium water in contact with the methanation reactor is very high in order to avoid corrosion of the reactor and the heat transfer apparatus (e.g., pipes). Highly purified water is expensive, and partitioning into two cycles reduces the amount of water in direct contact with the reactor, and therefore reduces the amount of highly purified water, which reduces the overall manufacturing cost.
[0024] In a preferred embodiment of the present invention, the reactor does not contain more than one catalyst. In other words, the reactor contains only one kind of catalyst, which avoids the need for different treatments or maintenance of multiple catalysts, and thus further reduces the production cost of synthesis gas.
[0025] In a preferred embodiment of the present invention, the catalyst in the methanation reactor contains Ni and / or Ru. The use of a catalyst containing Ni and / or Ru has the advantage of enabling a particularly high CO / CO2 conversion rate to methane, which makes it possible to reduce the size of the reactor and the plant itself as a whole.
[0026] Preferably, the feed gas
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[0027] In the context of the present invention, the term over-stoichiometric molar ratio means that carbon is in excess with respect to hydrogen
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[0028] To better understand this, it will be described based on two specific examples.
[0029] Reaction (I): (I) CO + 3H2 → CH4 + H2O In the case of, the molar ratio of the stoichiometric concentrations of CO and H2 is calculated using the molar concentrations of the educts as
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[0030] Reaction (II): (II) CO2 + 4H2 → CH4 + 2H2O In this case, the stoichiometric concentrations of CO2 and H2 are determined using the molar concentrations of the educt.
number
[0031] A common problem in the art is that, in order to ensure that the methanation reaction is efficient, a feed gas having a stoichiometric concentration of hydrogen relative to CO and / or CO2 must be provided. However, the “raw material” feed gas usually contains a stoichiometrically excess concentration of hydrogen relative to CO and / or CO2 (i.e., more carbon than is required for the methanation reaction). As a result, it is generally necessary to reduce the carbon concentration in the feed gas, for example with the help of a separation unit, before supplying the feed gas to the methanation reactor. The method of the present invention makes it possible to produce methane-containing synthesis gas using a stoichiometrically excess feed gas, thus eliminating the need for prior carbon reduction in the feed gas, which reduces the cost of synthesis gas production. Furthermore, the number of available sources of feed gas for methanation is greatly increased, including gases that are easily produced by biomass or coal gasification, by electrolysis, by co-electrolysis, or by-products of steel blast furnaces. The method of the present invention also makes it possible to use feed gases that are generally considered to be of low value due to their low calorific value. This means that the method of the present invention enables the use of gas that is not preferably used for any other purpose and is therefore inexpensive.
[0032] In a preferred embodiment of the present invention, the feed gas from step a) and the crude synthesis gas from step c) are transferred to a heat exchanger, where heat from the crude synthesis gas is transferred to the feed gas. In other words, heat is extracted from the crude synthesis gas and used to heat the feed gas. Preferably, the temperature of the crude synthesis gas decreases to less than 150°C in the heat exchanger. On the other hand, it is preferable that the temperature of the feed gas increases to at least 150°C, more preferably at least 200°C, in the heat exchanger.
[0033] Another aspect of the present invention is the provision of a synthesis gas production plant. The synthesis gas production plant comprises a feed gas source that provides a feed gas containing CO and / or CO2 as a carbon source and H2 as a first hydrogen source. The synthesis gas production plant further comprises a methanation reactor that produces crude synthesis gas containing methane and CO2 and heat as a byproduct from the feed gas. The methanation reactor comprises a catalyst comprising a compound selected from the group consisting of Ni, Co, Fe, Pd, Pt, Ru, Rh and combinations thereof. The synthesis gas production plant also comprises a feed gas supply line connecting the feed gas source and the methanation reactor, a separation unit comprising an absorption medium that separates the crude synthesis gas into a methane-enriched synthesis gas stream and a CO2-enriched exhaust gas stream, and a crude synthesis gas line connecting the methanation reactor and the separation unit. The separation unit is an amine scrubber, and the absorption medium is an amine solution. According to the present invention, the synthesis gas production plant further comprises a heat transfer apparatus comprising a heat exchanger and water as a heat transfer medium. The heat transfer device uses the heat generated in the reactor to regenerate the absorption medium.
[0034] Similar to the advantages of the method of the present invention, the plant of the present invention enables stabilization of the methanation reaction, avoids catalyst damage due to overheating, enables efficient production of crude synthesis gas, and reduces production costs because external energy is not required to regenerate the absorption medium. Another advantage similar to the method of the present invention is that the methanation reactor and the separation unit can be spaced apart from each other by the presence of a heat transfer device. Furthermore, the above-mentioned advantage of using water as the heat transfer medium in the method of the present invention applies to the plant of the present invention. In particular, a natural convection system of water / steam can be used, thereby avoiding the use of pumps to transfer water / steam from the methanation reactor to the separation unit.
[0035] In a preferred embodiment of the present invention, the feed gas contains H2O as a second hydrogen source. The advantages of the feed gas containing water described above in relation to the method of the present invention are applied mutatis mutandis to the plant of the present invention.
[0036] Preferably, the heat transfer apparatus comprises a first loop connecting the methane reactor and the heat exchanger, and a second loop connecting the separation unit and the heat exchanger. The advantages of using two loops in terms of the purity requirements of the heat transfer medium water, the risk of corrosion of the reactor and heat transfer apparatus, and the cost of producing purified water have been described above and are applied mutatis mutandis to the plant of the present invention.
[0037] In a preferred embodiment of the present invention, the synthesis gas production plant further includes a heat exchanger for transferring heat from crude synthesis gas to feed gas. This heat exchanger has the advantage of being able to use heat from the crude synthesis gas to preheat the feed gas before supplying it to the methane reactor. This reduces manufacturing costs because external energy is not required to raise the temperature of the feed gas and to lower the temperature of the crude synthesis gas.
[0038] Preferably, the reactor does not contain more than one catalyst. The advantages of a reactor containing only one catalyst as described above in relation to the method of the present invention apply mutatis mutandis to the plant of the present invention.
[0039] Preferably, the catalyst compound in the methanation reactor contains Ni and / or Ru. As mentioned above, the use of a catalyst containing Ni and / or Ru has the advantage of particularly high CO / CO2 conversion to methane, which allows for a reduction in reactor size and therefore a reduction in the overall plant size.
[0040] In a preferred embodiment of the present invention, a feed gas is supplied to a methane reactor in the plant of the present invention.
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[0041] The present invention will be described below with reference to the attached drawings for illustrative purposes. [Brief explanation of the drawing]
[0042] [Figure 1] Figure 1 shows a method and plant for producing synthesis gas according to a preferred embodiment of the present invention. [Modes for carrying out the invention]
[0043] Figure 1 shows a plant 100 from which feed gas 101 is supplied from a feed gas source (not shown). The feed gas 101 contains CO and CO2 as carbon sources 103, H2 as a first hydrogen source 105, and H2O as a second hydrogen source 107. In the illustrated embodiment, the feed gas 101 is supplied at room temperature and then transferred to a heat exchanger 109, which raises the temperature of the feed gas 101 to a temperature of 150°C to 300°C. The thus heated feed gas 110 is then transferred from the heat exchanger 109 to a methanation reactor 111 containing a catalyst 113. In the methanation reactor 111, the heated feed gas 110 is converted into a crude synthesis gas 115 containing methane (CH4), CO2, and water. The crude synthesis gas 115 leaves the methanation reactor 111 at a temperature of 250°C or lower and is transferred to the heat exchanger 109. In the heat exchanger 109, the temperature of the crude synthesis gas 115 is reduced, and the extracted heat is transferred to the feed gas 101. The cooled crude synthesis gas 117, having a temperature of approximately 150°C, is then transferred from the heat exchanger 109 to the separation unit 119. The separation unit 119 includes an amine scrubber 121 and a reboiler 123. The amine scrubber 121 uses an amine solution 122 to separate the cooled crude synthesis gas 117 into methane-enriched synthesis gas vapor 125 and a CO2-enriched exhaust gas flow 127. During this process, the amine solution absorbs CO2 from the crude synthesis gas 117 and is transferred to the reboiler 123 as a CO2-saturated amine solution 129. In the reboiler 123, the CO2-saturated amine solution 129 is regenerated into a CO2-reduced amine solution 131, which is then returned to the amine scrubber 121. This regeneration process utilizes the heat provided by the methanation reactor 111. Specifically, the exothermic methanation reaction in the methanation reactor 111 generates heat. This heat is used in the heat transfer device 133 to raise the temperature of the water used as the heat transfer medium. The heat transfer device 133 comprises a first loop 135 connecting the heat exchanger 137 to the methanation reactor 111 and a second loop 139 connecting the heat exchanger 137 to the reboiler 123.In the first loop 135, water 141 is transferred from the heat exchanger 137 to the methane reactor 111, where the water 141 evaporates due to the heat provided by the exothermic methane reaction, resulting in a flow of steam 143. This steam 143 is then transferred to the heat exchanger 137 to raise the temperature of the water 145 in the second loop 139. As a result of the heat transfer occurring from the steam 143 in the first loop 135 to the water 145 in the second loop 139, the steam 143 condenses back into water 141, while the water 145 in the second loop 139 evaporates to become a flow of steam 147. The steam 147 is transferred to the reboiler 123 to regenerate the CO2-saturated amine solution 129. Specifically, in the reboiler 123, the heat from the steam 147 is extracted to raise the temperature of the CO2-saturated amine solution 129, resulting in a CO2-reduced amine solution 131 and a CO2-enriched exhaust gas flow 127. The CO2-enriched exhaust gas flow 127 is then used further for other purposes, such as carbonation of beverages, while the CO2-reduced amine solution 131 is returned from the reboiler 123 to the amine scrubber 121.
Claims
1. A method for producing a methane-containing synthesis gas stream, including the following steps: a) As a carbon source (103), CO and / or CO ２ And as the first hydrogen source (105), H ２ A step of providing a feed gas (101) containing the following; b) The temperature of the feed gas (101) in step a) is set to a temperature T of 150°C to 300°C. １ The process of adjusting to; c) The feed gas (110) from step b) is reacted in a methane reactor (111) to produce heat, methane, and CO ２ A step of producing a crude synthesis gas (115) containing the following, wherein the methanation reactor (111) contains a catalyst (113) comprising a compound selected from the group consisting of Ni, Co, Fe, Pd, Pt, Ru, Rh and combinations thereof; d) A step of transferring the crude synthesis gas (115) to a separation unit 119 containing an absorption medium, wherein the separation unit is an amine scrubber 121 and the absorption medium is an amine solution (122); e) The crude synthesis gas (115) is separated in the separation unit (119) into a methane-enriched synthesis gas stream (125) and CO ２ A step of separating it from a saturated absorption medium (129); f) By using the heat generated in the methanation reactor, raise the temperature of the CO ２ enriched absorption medium (129) to regenerate the CO ２ saturated absorption medium (129), and generate an exhaust gas stream (127) containing the absorption medium (131) with reduced CO ２ and CO ２ ; Here, the heat from the methanation reactor (111) is transferred to the separation unit (119) with the help of a heat transfer device (133) which includes a heat exchanger (137) and water as a heat transfer medium (141, 143, 145, 147).
2. The feed gas (101) is used as a second hydrogen source (107) ２ The method according to claim 1, comprising O.
3. The method according to claim 1 or 2, wherein the heat transfer device (133) comprises a first loop (135) connecting the methane reactor (111) to the heat exchanger (137) and a second loop (139) connecting the separation unit (119) to the heat exchanger (137).
4. The method according to any one of claims 1 to 3, wherein the methanation reactor (111) does not contain more than one type of catalyst (113).
5. The method according to claim 1 or 4, wherein the compound of the catalyst (113) is Ni and / or Ru.
6. A synthesis gas production plant (100) equipped with the following: As a carbon source (103), CO and / or CO ２ And as the first hydrogen source (105), H ２ A feed gas source that provides a feed gas (101) containing the following; From the feed gas (101), heat, methane, and CO ２ A methanation reactor (111) for producing crude synthesis gas (115) containing the following, the methanation reactor (111) comprising a catalyst (113) containing a compound selected from the group consisting of Ni, Co, Fe, Pd, Pt, Ru, Rh and combinations thereof; A feed gas supply line connecting the feed gas source to the methane reactor (111); It contains an absorption medium and converts crude synthesis gas into a methane-enriched synthesis gas stream and CO2 ２ A separation unit (119) separates the enriched exhaust gas flow, wherein the separation unit is an amine scrubber (121) and the absorption medium is an amine solution (122); A crude synthesis gas line connecting the methane reactor (111) to the separation unit (119); A heat exchanger (137) and a heat transfer device (133) containing water as a heat transfer medium (141, 143, 145, 147) for transferring the heat generated in the methane reactor (111) to the separation unit (119) to regenerate the absorption medium (129).
7. The synthesis gas production plant according to claim 6, wherein the heat transfer device (133) comprises a first loop (135) connecting the methane reactor (111) to the heat exchanger (137) and a second loop (139) connecting the separation unit (119) to the heat exchanger (137).
8. The synthesis gas production plant according to claim 6 or 7, further comprising a heat exchanger (109) for transferring heat from crude synthesis gas (115) to feed gas (101), Includes.
9. The synthesis gas production plant according to any one of claims 6 to 8, wherein the methane reactor (111) does not contain more than one type of catalyst (113).
10. The synthesis gas production plant according to any one of claims 6 to 9, wherein the compound of the catalyst (113) is Ni and / or Ru.
Citation Information
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