Method and system for producing one or more olefins

Abstract

The present invention relates to a process (100, 200) for producing one or more olefins (103), in which one or more paraffins are reacted in one or more reaction steps (10) to obtain a mixed product (102), the reaction step(s) (10) being carried out using heat of combustion, the mixed product (102) containing one or more olefins, hydrogen, and methane, and an exhaust gas (112) is formed using the mixed product (102) or a portion thereof in one or more separation steps (20, 21), the exhaust gas (112) being substantially free of one or more olefins but containing hydrogen from the mixed product (102) or a portion thereof. and methane, said flue gas (112) or a part thereof is permanently discharged from said process (100), a fuel gas (111) is used to provide the heat of combustion, the molar ratio of hydrogen to methane in said flue gas (112) is at least equal to that in said mixed product (102) and said molar ratio in said fuel gas (111) is lower than that in said flue gas (112), and flue gas (121) containing carbon dioxide is formed during the provision of the heat of combustion, and said flue gas (121) or a part thereof is subjected to carbon dioxide capture (30). Corresponding systems are also the subject of the present invention.

Description

[Technical Field]

[0001] The present invention relates to a process and system for producing one or more olefins. [Background technology]

[0002] Processes and systems for producing olefins (alkenes), particularly from paraffins (alkanes), are known. See, inter alia, the articles "Ethylene" and "Propylene" in Ullmann's Encyclopedia of Industrial Chemistry, published online April 15, 2009, and September 16, 2013.

[0003] The selectivity of processes and systems for producing olefins can be significantly improved, which means, for example, that more than 75 mol% of the carbon in the feedstock ultimately ends up in the desired product, with only a small amount of carbon in by-products such as methane. The corresponding processes are endothermic and non-oxidative, i.e., the energy supply can be via another energy source. Heating can be achieved by using electric current or by burning fuel, each of which is known in various variants. The invention is not limited to any particular variant.

[0004] In addition to direct resistive heating of the catalyst itself or the support on which it is applied, it is also possible to use resistive heating elements for heating with electric current, for example with a washcoat. It is also possible to electrically superheat the process gas and then pass it through the catalyst bed at high temperature (if a catalyst is used). In this case, an adiabatic reaction is carried out. It is also possible to provide several corresponding superheating steps followed by an aligned adiabatic catalyst bed.

[0005] In addition to direct heating, in which a heating medium, such as a heating element, a heating sleeve, or a resistively heated catalyst support, is in material contact with the process gas or with the reaction tube through which the process gas flows, indirect electrical heating can also be used, as reported, for example, in WO 2020 / 002326 and is already known in previous publications.

[0006] Such indirect electrical heating can be accomplished using electrical radiant heating elements suitable for heating at the high temperatures required for the above-described reactions, with such heating elements positioned so as not to be in direct contact with the reaction tubes, with heat transfer occurring primarily or exclusively in the form of radiant heat.

[0007] Heating by combustion can be achieved in a furnace or heat exchanger equipped with a radiant zone, where burners can be used in various numbers, positions, and configurations in the combustion chamber, and can be operated with a wide variety of fuel gases, with or without the addition of other combustible media, and with or without heating of the fuel gas, combustion air, or other oxygen-containing gas mixture. Again, intermittent heating of the catalyst bed by oxidation or the use of a fluidized bed reactor with separate reaction and combustion chambers is possible. Heat recovery is also possible, for example, in a convection bed. This heat recovery can be used, for example, for feed preheating, steam generation, steam heating, air preheating, etc.

[0008] Paraffins or other carbon-containing feedstocks used to produce olefins can also be adapted to produce hydrogen during the reaction. This is true, for example, for paraffinic compounds with 2 to 4 carbon atoms, but also to some extent for long-chain hydrocarbons such as methanol or ethanol.

[0009] The mixed product of such a process is relatively low in methane and relatively high in hydrogen in the so-called C1 minus fraction, typically 80 mole percent hydrogen and 20 mole percent methane. The C1 minus fraction contains, among other things, compounds with one carbon atom, including carbon monoxide and carbon dioxide, the aforementioned methane, and lighter compounds, such as the aforementioned hydrogen.

[0010] Corresponding equivalents apply, for example, to so-called gas crackers, ie cracking furnaces designed for gaseous feedstocks in steam cracking processes and propane dehydrogenation.

[0011] Essentially, the above-described processes produce highly selective olefins and so-called C1 minus "energy streams" (named after their typical use in combustion, i.e., energy utilization) with low carbon dioxide intensity. In the case of propane dehydrogenation, this stream may also contain small amounts of hydrocarbons with, for example, two carbon atoms. In the following, this stream will be referred to as exhaust gas. The exhaust gas usually contains the total amount or a substantial amount, in particular more than 90% or more than 95%, of all components of the corresponding type obtained from the mixed product of the corresponding process.

[0012] The term "carbon dioxide intensity" correlates to the amount of carbon dioxide produced by the combustion of a gas or mixture of gases or other fuels. For example, a methane stream containing no hydrogen (e.g., natural gas, assuming a simple 100% methane content) has a carbon dioxide intensity of about 0.2 tonnes of carbon dioxide per megawatt-hour based on its lower heating value. On the other hand, a flue gas of the type described above containing, for example, 80 mole % hydrogen and 20 mole % methane has a carbon dioxide intensity of only about 0.09 tonnes of carbon dioxide per megawatt-hour based on its lower heating value.

[0013] Typically, the corresponding exhaust gas is intended for direct incomplete combustion in an olefin production process or system. Simply put, assuming the same energy consumption (gigajoules per ton of valuable product) in this type of process or system, the carbon dioxide intensity of a process using incomplete combustion with a hydrogen-rich exhaust gas is only 45% of that of a process using incomplete combustion with methane. This can be a crucial advantage. As mentioned above, processes that are highly selective for producing olefins typically produce less carbon dioxide, e.g., 0.4 tonnes of carbon dioxide per ton of valuable product, or even less.

[0014] However, if the aim is to decarbonise direct emissions ("Scope 1" emissions) as much as possible (e.g. by 95%), the corresponding process can be difficult. The present invention therefore aims to provide an advantageous solution for such cases. Summary of the Invention

[0015] As a remedy to this situation, the present invention proposes a process and a system for obtaining one or more olefins having the features of the independent claims. Embodiments are the subject of the dependent claims and the following description.

[0016] As already noted above, the specific direct ("Scope 1") carbon dioxide emissions of the olefin production processes described above are already extremely low. However, completely reducing these emissions is particularly difficult.

[0017] Full electrification of all energy supply units, including the reactors used, may not yet be commercially viable or may be too costly. Incomplete combustion with a very hydrogen-rich combustion medium (approximately 99-100 mol% hydrogen) is in principle suitable for reducing such emissions. The first option for this is hydrogen obtained from the aforementioned flue gas, from which the methane content must be recovered. However, the hydrogen obtained from the flue gas is usually not sufficient to meet the energy demand, even with a highly optimized process energy. In a typical gas cracker, for example, hydrogen only accounts for about 50% of the energy supply.

[0018] Therefore, it is first appropriate to try to optimize the energy use in the process, especially with the partial support of electrification. Finally, an additional supply of hydrogen is required. In particular, so-called "green" hydrogen, obtained by electrolysis of water powered by renewable electric current, is conceivable. However, this option is very costly and energy-intensive. On the other hand, "blue" hydrogen, for example from methane reforming with separation of carbon dioxide from flue gas (carbon capture), can also be used. However, this variant also involves significant heat losses in the methane used and is costly.

[0019] Instead of prior reduction of the carbon dioxide content in the flue gas, emissions can also be reduced by separating carbon dioxide from the flue gas of combustion processes or units used in the olefin production process (crackers, furnaces, boilers, catalyst regenerators, etc.). However, in the corresponding flue gas, the pressure / partial pressure of carbon dioxide is very low, which is further reduced by the high proportion of hydrogen combustion.

[0020] The present invention solves these problems at least in part by deliberately not burning hydrogen-rich exhaust gases, but instead burning fuels rich in methane or hydrocarbons, and releasing the exhaust gases or hydrogen therefrom, particularly towards the system boundary. At first glance, this solution seems counter to common sense, since it would initially seem desirable to avoid all carbon dioxide formation, which is exactly what the present invention proposes.

[0021] The solution proposed herein is therefore the opposite of prior art solutions that produce hydrogen-rich fuel gas streams.

[0022] For example, WO 2023 / 049570 proposes producing a hydrogen-rich fuel gas stream by reforming a hydrocarbon-containing feedstock and subjecting the resulting process gas to water-gas shift and carbon dioxide separation. According to the embodiments described in this document, the remaining hydrogen-rich stream can be advantageously combusted to provide thermal energy. EP 3,249,027 proposes a process for producing olefins by steam cracking using one or more tubular reactors. The tubular reactor, or at least one of the tubular reactors, is heated using both combustion heat generated by burning at least one fuel and electrical heat generated by electrical energy. However, there is no proposal to discharge the hydrogen-rich stream from the process rather than combusting it. The process typically involves the reaction of a paraffinic feedstock, which typically contains primarily or exclusively hydrocarbons having 2 to 4 carbon atoms. For example, ethane, propane, or liquefied petroleum gas (LPG) can be used. To obtain olefins, particularly ethylene and propylene, a product mixture containing these olefins is formed. The product gas also contains at least methane and hydrogen, with the molar ratio of hydrogen to methane being greater than 0.4, particularly greater than 1, and even greater than 2 or 4. The energy demand of the process is met, at least in part, by incomplete combustion of the hydrocarbons or hydrogen, or a mixture thereof.

[0023] Within the scope of the present invention, a product fraction is then discharged from the process and / or released at the system boundary. This product fraction essentially comprises compounds with one carbon atom and / or lighter compounds. This product fraction can be an exhaust gas or a fraction formed from the exhaust gas. The molar ratio of hydrogen to methane in this exhaust gas is equal to or greater than the molar ratio of hydrogen to methane in the product mixture. An energy stream, i.e., fuel gas, is supplied to the process externally, i.e., from outside the system boundary, and serves to compensate for the incomplete combustion. The molar ratio of hydrogen to methane in this energy stream is lower than that in the exhaust gas and / or in the fraction formed from the exhaust gas. During the incomplete combustion, a flue gas is formed, at least a portion of which is supplied to a carbon recovery process.

[0024] The term "substantially," as used herein, particularly in the context of a claimed composition, material stream, etc., should be understood to mean that additional components may be present in addition to the essential components, but that the essential characteristics of the claimed composition are not significantly altered by these additional components. For example, a product fraction containing "compounds having substantially one carbon atom and / or lighter compounds" contains so little hydrocarbons, particularly olefins, having two or more carbon atoms that the loss of valuable products when the hydrocarbons are released at the system boundary is minimal. Specifically, this loss may be less than 1%, less than 0.1%, or less than 0.01% of such higher hydrocarbons. This percentage may be expressed as a mole fraction, a mass fraction, or a volume fraction.

[0025] Generally, the present invention proposes a process for producing one or more olefins, wherein one or more paraffins are reacted to obtain a mixed product in one or more reaction steps, the reaction step(s) being carried out using heat of combustion, the mixed product containing one or more olefins, hydrogen, and methane, an exhaust gas is formed using the mixed product or a portion thereof in one or more separation steps, the exhaust gas being substantially free of the one or more olefins but containing hydrogen and methane from the mixed product or a portion thereof, the exhaust gas or a portion thereof being permanently discharged from the process, a fuel gas is used to provide the heat of combustion, the molar ratio of hydrogen to methane in the exhaust gas is at least equal to that in the mixed product and that in the fuel gas is lower than that in the exhaust gas, a flue gas containing carbon dioxide is formed during the provision of heat of combustion, and the flue gas or a portion thereof is subjected to carbon dioxide recovery.

[0026] The advantage of the process proposed here is, in particular, that the separation of carbon dioxide from flue gas is simplified due to the high partial pressure. Achieving complete decarbonization using variants including electrification and pure hydrogen combustion options is challenging as discussed above and currently appears insurmountable or impractical. Therefore, within the scope of the present invention, the removal of carbon dioxide from flue gas is optimized. The present invention provides surprising synergistic effects.

[0027] The present invention involves permanently venting the exhaust gas or a portion thereof from the process. The term "permanently venting from the process" means that the exhaust gas or the vented portion thereof, in particular having the same hydrogen content as the exhaust gas, is not combusted in the process and generates heat, or only a small portion thereof, for example less than 10%, less than 5%, or less than 1%, is combusted. Instead, a low-hydrogen or (substantially) hydrogen-free fuel gas is combusted. The exhaust gas or a corresponding portion permanently vented from the process is released at the system boundary, in particular of the system used in the process, and does not return to the process itself or the corresponding system. In this way, the corresponding hydrogen does not "dilute" the flue gas and therefore may not make carbon dioxide separation more difficult.

[0028] For example, in embodiments of the present invention, it is possible to remove fuel gas or a portion thereof from the gas supply line (pipeline) and return tail gas or a portion thereof that has been permanently vented from the process back to the gas supply line. In this way, the process proposed in accordance with embodiments of the present invention can capture more carbon dioxide than would be possible with a process that relies entirely on internal utilization of the hydrogen-rich tail gas. Thus, a system according to one embodiment of the present invention lends itself to additional carbon dioxide removal. At the same time, in a corresponding embodiment of the present invention, an output stream with a lower carbon dioxide intensity is available that can be provided for use elsewhere. Removal from the same pipeline or, in addition to being returned to the same pipeline, removal may also occur from a source different from the return sink.

[0029] In the illustrated example, a gas pipeline can be partially decarbonized using equipment such as a steam cracker. A carbon dioxide intensity feedstock, e.g., methane-rich natural gas, with 0.2 tonnes of carbon dioxide per megawatt-hour based on its lower heating value, is partially replaced with a carbon dioxide intensity flue gas, e.g., 0.09 tonnes of carbon dioxide per megawatt-hour based on its lower heating value. In olefin production, capturing the carbon dioxide provides an advantage here, since it is not actually released into the atmosphere (e.g., through a certification process).

[0030] In an embodiment of the invention, the tail gas or a portion thereof may be subjected to one or more tail gas separation steps to obtain a first tail gas fraction that is enriched in hydrogen and depleted in methane relative to the tail gas, and a second tail gas fraction that is depleted in hydrogen and depleted in methane relative to the tail gas, thereby providing, inter alia, a pure hydrogen product in the form of the first tail gas fraction.

[0031] By properly designing the methane and hydrogen to be separated (at least partially), it is possible to create an export stream with even lower carbon dioxide intensity, down to zero (hydrogen). Thus, for example, if more than 60%, especially more than 95%, of the carbon dioxide is captured from the flue gas, the direct carbon dioxide emissions of the exported hydrogen will be very low ("blue" hydrogen).

[0032] In both cases, the first flue gas fraction or a part of it can be permanently discharged from the process, but it is also possible to use it separately from the fuel gas to obtain additional combustion heat. Because pure hydrogen combusts well, no carbon dioxide separation is performed in the resulting exhaust gas. However, the second flue gas fraction or a part of it can be used for "normal" combustion due to its corresponding methane content, with downstream carbon dioxide recovery.

[0033] In embodiments of the present invention, the one or more flue gas separation steps may include one or more membrane separation steps and / or one or more adsorption separation steps. These steps may be performed directly in the separation section or in a separate unit that processes the flue gas. The separation may include compression and cryogenic separation, as well as (vacuum) pressure swing adsorption, membrane processing, or a combination of these processes, which are generally known to those skilled in the art.

[0034] As previously mentioned, in embodiments of the present invention, greater than 60% or even greater than 95% of the carbon dioxide contained in the flue gas or portion thereof that is subjected to carbon dioxide capture can be captured during carbon dioxide capture, resulting in the advantages discussed above.

[0035] In embodiments of the present invention, the carbon dioxide can be recovered using one or more absorption liquids, as is known in principle. For example, amine washes and caustic washes can be used alone or in any combination. Alternatively, simple compression and condensation can be performed (as in the case of an oxyfuel furnace, as described below).

[0036] In embodiments of the present invention, the fuel gas or part of it may be burned with an oxygen-rich oxidant gas. The oxidant in such furnaces can therefore be enriched in oxygen or even be (almost) completely oxygen (so-called oxyfuel furnaces). In this case, the flue gas consists almost entirely of hydrogen and carbon dioxide, making carbon recovery from these furnaces particularly easy.

[0037] Where possible, the reaction step(s) may also be carried out using electrically supplied heat, thereby reducing the need to incorporate fossil fuels.

[0038] In embodiments of the present invention, the fuel gas may be a methane-rich gas or a mixed gas. For example, the fuel gas may be fossil methane, such as natural gas, in which case, as noted above, the formed carbon dioxide may be almost completely (e.g., 95%) removed from the flue gas. This reduction in emissions may be attributed to the olefin product and / or the hydrogen-rich send-out stream.

[0039] Biogas may be supplemented. This results in "negative" direct carbon dioxide emissions, as the carbon from the biogas is almost completely removed from the flue gas in the carbon capture process ("bio-CO2" is captured). Negative emissions can be attributed to olefin products and / or hydrogen-rich send-out streams. Feedstocks can be fossil-derived, or from recycled or biological sources. It is essential that the feedstock enhances the hydrogen / methane ratio in the reaction.

[0040] The resulting hydrogen-rich stream can be at low pressure for direct use in incomplete combustion, or at high pressure for feeding this stream into the hydrogen value chain and / or pipelines. Thus, specifications can vary widely, from typical flue gas to 99.9999 mole % hydrogen.

[0041] A system for producing one or more olefins is designed to: convert one or more paraffins to obtain a mixed product in one or more reaction steps; utilize combustion heat to carry out the reaction step(s); form a mixed product containing one or more olefins, hydrogen, and methane; use the mixed product or a portion thereof in one or more separation steps to form an exhaust gas; form an exhaust gas from the product mixture or a portion thereof substantially free of the one or more olefins and containing hydrogen and methane; permanently vent the exhaust gas or a portion thereof from the system; and use a fuel gas to obtain combustion heat, wherein the molar ratio of hydrogen to methane in the exhaust gas is at least equal to that in the mixed product and the molar ratio of hydrogen to methane in the fuel gas is lower than that in the exhaust gas, and a flue gas containing carbon dioxide is formed during the supply of combustion heat, and the flue gas or a portion thereof is subjected to carbon dioxide recovery.

[0042] For further features and advantages of the corresponding system and its embodiments, explicit reference is made to the above description of the proposed process according to the invention and its embodiments, since these features and advantages apply to that process as well.

[0043] The same applies to systems designed to carry out processes according to any embodiment of the present invention.

[0044] Before describing embodiments of the present invention with reference to the accompanying drawings, some further aspects of the present invention and non-inventive embodiments will be briefly described, which can be used in any combination with the embodiments described above and below.

[0045] In an embodiment of the present invention, the separation of methane and hydrogen in a gas cracker also lends itself to applications for methane export for direct pipeline export, hydrogen production, methane pyrolysis, synthesis gas production, production of value products or its use in power systems, among others.

[0046] Separation of methane and hydrogen in a gas cracker is also meaningful if neither hydrogen nor methane is being exported. Separation allows for incomplete combustion of either hydrogen or methane in various processes. This means that only the carbon dioxide resulting from the incomplete combustion of methane needs to be recovered.

[0047] Hydrogen and methane separation can also be performed in combination with the use of appropriately tailored furnace designs, and depending on the implementation, various "hybrid" system designs can be envisioned, such as a hydrogen furnace combining hydrogen combustion with a methane furnace (with optional carbon dioxide capture), a hydrogen furnace combining hydrogen combustion with a methane oxyfuel furnace (with optional carbon dioxide capture), and a hydrogen furnace combining hydrogen combustion with an electric furnace and methane export to the value chain.

[0048] Biogas can be captured even without carbon dioxide capture, thus allowing energy export with low carbon dioxide intensity (but without a negative carbon dioxide balance). Embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0049] [Figure 1] 1 illustrates a system according to an embodiment of the present invention. [Figure 2] 1 illustrates a system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0050] The embodiments described below are presented solely to facilitate the reader's understanding of the claimed features and the features described above. These features are merely representative examples and are not intended to be a comprehensive and / or limiting description of the features of the present invention. It is understood that the advantages, embodiments, examples, functions, features, structures, and / or other aspects described above and below should not be construed as limiting the scope of the present invention as defined by the claims or equivalents of the claims. It is also understood that other embodiments may be utilized and changes may be made without departing from the scope of the claimed invention.

[0051] Various embodiments of the invention may comprise, have, consist of, or consist essentially of other useful combinations of the described elements, components, features, parts, steps, means, etc., even if not specifically described herein. Furthermore, the present disclosure may cover other inventions that are not currently claimed but may be claimed in the future, particularly if they fall within the scope of the independent claims.

[0052] Descriptions of apparatus, devices, arrangements, systems, etc. according to embodiments of the invention may also apply to methods, processes, procedures, etc. according to embodiments of the invention, and vice versa. Identical elements, process steps, etc. that have the same effect, that correspond to each other in function, that are structurally identical, or that have equivalent structure may be indicated by the same reference symbols.

[0053] FIG. 1 illustrates a process, generally designated 100, in accordance with one embodiment of the present invention.

[0054] The process shown in Figure 1 comprises one or more reaction stages 10 to which a reaction feed 101 is supplied, which, depending on the design of the reaction stage(s) 10, comprises, among other things, one or more paraffins. The reaction feed 101 is reacted to obtain a mixed product 102, where one or more of the processes detailed above can be used.

[0055] The reaction step(s) 10 are carried out using the heat of combustion obtained from the combustion of a methane-containing fuel gas 111, which in the example of process 100 shown in Figure 1 can be taken from a pipeline 110. During combustion, flue gas 121 is formed which is sent to the carbon dioxide removal step 30. The separated carbon dioxide is designated 122 and the carbon dioxide-depleted flue gas is designated 123.

[0056] The mixed product 102 containing one or more olefins, hydrogen, and methane is then subjected to one or more separation steps 20 to form one or more product fractions 103 substantially containing one or more olefins, and a tail gas fraction 112 substantially free of the one or more olefins but containing at least a portion of the hydrogen and methane from the mixed product.

[0057] As a feature of this embodiment of the present invention, the molar ratio of hydrogen to methane in the exhaust gas fraction 112 is at least equal to or greater than the molar ratio of hydrogen to methane in the mixed product 102, and the molar ratio of hydrogen to methane in the fuel gas 111 is lower than the molar ratio in the exhaust gas fraction 112.

[0058] The exhaust gas 112 is permanently vented from the process 100. More specifically, the fuel gas 111 is removed from the gas supply line 110 and the exhaust gas 112 is returned to the gas supply line 110.

[0059] FIG. 2 illustrates a process, generally designated 200, in accordance with one embodiment of the present invention.

[0060] 2, flue gas 112 is subjected to flue gas separation step 21 to obtain a first flue gas fraction 113 that is enriched in hydrogen and enriched in methane relative to flue gas 112, and a second flue gas fraction 114 that is enriched in hydrogen and enriched in methane relative to flue gas 112. First flue gas fraction 113, or a portion thereof, may be permanently discharged from process 200 or may be used for other purposes as described above. Uses of second flue gas fraction 114 have also been described.

[0061] For the production of pure hydrogen as a "low carbon" energy carrier, a highly simplified example is given below comparing an "intentional" variant to produce blue hydrogen using, for example, autothermal reforming (ATR) and carbon dioxide capture from syngas (Table 1) with a variant according to an embodiment of the invention using a cracker and carbon dioxide capture (Table 2).

[0062] Table 1 TIFF2025529556000002.tif72170

[0063] Table 2 TIFF2025529556000003.tif132170

[0064] The "intentional" variant in Table 1 to produce blue hydrogen requires approximately 133 MW of methane (75% efficiency), or in the best case 125 MW (80% efficiency) to produce 100 MW of hydrogen. A corresponding amount of carbon dioxide must be removed by carbon dioxide capture. The small amount of additional energy available in the form of delivery steam is not considered here.

[0065] The integrated variant according to the embodiment of the present invention and Table 2 also generates additional energy consumption due to carbon dioxide capture, but it is relatively small, about 120 MW of methane per 100 MW of hydrogen. This process does not yet take into account the fact that carbon dioxide separation from the exhaust gas is greatly simplified (due to its high partial pressure). It also does not take into account the energy required to separate methane and hydrogen, which can be fully electrified and is also required for the variant shown in Table 1.

[0066] In summary, it can be concluded that the variant according to the invention requires at least 10% less thermal energy and 10% less carbon dioxide for the same amount of hydrogen produced, and does not require an "intentional" process (a system for producing blue hydrogen). This advantage is offset by the need for flue gas cleaning in the steam cracker and separation of methane and hydrogen (which, as mentioned above, is also necessary for other systems), but this investment pays off both for the decarbonization of olefins and for the "low carbon" energy stream. As an additional advantage, the variant according to the invention eliminates the problem of the formation of nitrogen oxides during combustion.

Claims

1. A process (100, 200) for producing one or more olefins (103), comprising reacting one or more paraffins to obtain a mixed product (102) in one or more reaction steps (10), said reaction step(s) (10) being carried out using heat of combustion, said mixed product (102) containing one or more olefins, hydrogen, and methane, and an exhaust gas (112) formed using said mixed product (102) or a portion thereof in one or more separation steps (20, 21), said exhaust gas (112) being substantially free of one or more olefins, but said mixed product (103) being free of methane. 2) or a portion thereof, wherein the flue gas (112) or a portion thereof is permanently discharged from the process (100), and a fuel gas (111) is used to provide combustion heat, the molar ratio of hydrogen to methane in the flue gas (112) being at least equal to that in the mixed product (102) and the molar ratio in the fuel gas (111) being lower than that in the flue gas (112), and a flue gas (121) containing carbon dioxide is formed during the provision of combustion heat, and the flue gas (121) or a portion thereof is subjected to carbon dioxide capture (30).

2. 2. The process (100) of claim 1, wherein the fuel gas (111), or a portion thereof, is removed from the gas supply line (110) and the tail gas (112), or a portion thereof, permanently discharged from the process is returned to the gas supply line (110).

3. 2. The process (200) of claim 1, wherein the flue gas (112) or a portion thereof is subjected to one or more flue gas separation steps (21) to obtain a first flue gas fraction (113) enriched in hydrogen and depleted in methane relative to the flue gas (112) and a second flue gas fraction (114) enriched in hydrogen and depleted in methane relative to the flue gas (112).

4. The process (200) of claim 3, wherein the first tail gas fraction (113) or a portion thereof is permanently discharged from the process (200).

5. The process (200) of claim 3, wherein the first exhaust gas fraction (113), or a portion thereof, is used separately from the fuel gas (111) to provide additional combustion heat.

6. The process (200) of any one of claims 3 to 5, wherein the fuel gas (111) comprises a second tail gas fraction (114) or a portion thereof.

7. The process (200) according to any one of claims 3 to 6, wherein the one or more exhaust gas separation steps (20, 21) comprise one or more membrane separation steps and / or one or more adsorptive separation steps.

8. 8. The process (100, 200) of any one of claims 1 to 7, wherein during the carbon dioxide recovery (30), more than 60% of the carbon dioxide contained in the flue gas (121) or portion thereof subjected to the carbon dioxide recovery (30) is recovered.

9. The process (100, 200) of any one of claims 1 to 8, wherein the carbon dioxide capture (30) is carried out using one or more absorption liquids.

10. The process (100, 200) according to any one of claims 1 to 9, wherein the fuel gas (111) or a part thereof is combusted with an oxygen-rich oxidant gas.

11. The process (100, 200) according to any one of claims 1 to 10, further comprising carrying out the reaction step(s) (10) using electrically supplied heat.

12. The process (100, 200) of any one of claims 1 to 11, wherein the fuel gas is a methane-rich gas or gas mixture.

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