Autothermal cracking of hydrocarbons

Abstract

The invention relates to a process for producing olefins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons in an autothermal reactor, said process comprising: pre-heating an oxygen containing stream and a hydrogen and / or methane containing stream outside the autothermal reactor; feeding the pre-heated oxygen containing stream and the pre-heated hydrogen and / or methane containing stream into a burner of the autothermal reactor; generating steam in a combustion zone of the autothermal reactor; pre- heating a feed stream containing hydrocarbons outside the autothermal reactor; feeding the pre-heated feed stream containing hydrocarbons into the autothermal reactor; mixing the steam generated in the combustion zone with the pre- heated feed stream containing hydrocarbons in a mixing and cracking zone of the autothermal reactor, by feeding the steam and the pre-heated feed stream containing hydrocarbons into the mixing and cracking zone from substantially opposite directions, and pyrolytically cracking the hydrocarbons to provide an effluent containing olefins wherein the olefins comprise ethylene and acetylene; subjecting at least a part of the effluent containing olefins to hydrogenation of acetylene in the gas phase in the presence of a heterogeneous catalyst at a temperature of at least 200 °C, thereby obtaining an ethylene-enriched stream and heat.

Description

[0001] AUTOTHERMAL CRACKING OF HYDROCARBONS

[0002] Field of the invention

[0003] The present invention relates to a process for producing olefins from a feed stream containing hydrocarbons, by pyrolytic cracking of the hydrocarbons in an autothermal reactor .

[0004] Background of the invention

[0005] Pyrolytic cracking of hydrocarbons in a cracker furnace is a petrochemical process that is widely used to produce olefins (such as ethylene, propylene, butylenes and butadiene) and optionally aromatics (such as benzene, toluene and xylene) . Where such pyrolytic cracking is performed in the presence of dilution steam, this is referred to as "steam cracking". The feed stream to such a pyrolytic cracking process may include one or more of ethane, propane, butane, liquefied petroleum gas (LPG) , naphtha and hydrowax. In such a pyrolytic cracking process, the hydrocarbons containing stream is converted under the influence of heat, and substantially in the absence of oxygen, into an olefins containing effluent.

[0006] Although pyrolytic steam cracking in cracker furnaces is the industry standard for producing olefins, it has several disadvantages. The process produces large amounts of carbon dioxide. The heat that is needed to effect the pyrolytic cracking of the hydrocarbon stream is provided by the combustion of fuel gas, typically comprising hydrogen and methane, in a burner of the cracker furnace, i.e. the heat for the pyrolytic cracking is provided externally. Combustion of a fuel gas comprising hydrogen and methane results in the production of a flue gas comprising water and carbon dioxide. Generally, carbon dioxide from such flue gas may have to be emitted into the Earth' s atmosphere and / or may have to be captured in another form thereby preventing such emission. A distinction can be made between Carbon Capture and Storage (CCS) and Carbon Capture and Use (CCU) which both involve carbon dioxide capture which is cumbersome, requiring additional equipment, and therefore relatively expensive. In addition, CCS further increases the general costs of chemicals manufacturing because of the required energy expenditure for compression and distribution to carbon dioxide storage.

[0007] In addition, the flue gas also comprises nitrogen oxide (NOx) , which is a further undesirable by-product of the steam cracking reaction. N0xcan be removed from the flue gas, for example by using a DeNOx system, but this necessitates an additional step in the process and increases the overall cost of the olefins manufacture.

[0008] Furthermore, notable amounts of coke are formed on the inside of the tubes / coils (carrying the hydrocarbon feed and where the pyrolytic cracking reaction takes place) suspended in the furnace, due to the provision of heat from outside of the furnace, which necessitates regular furnace shutdowns to remove the coke build-up from the tubes / coils. The tubes / coils are typically decoked using a mixture of steam and air. To help reduce the formation of coke, sometimes sulphur is added to the hydrocarbon feed stream. However, this then means that further treatment is required to remove H2S from the off-gas process stream.

[0009] Moreover, aside from yielding the desired olefin products, depending on the hydrocarbon feed stream and reactor conditions used, the process can also yield (aside from coke) substantial amounts of other less desirable products such as methane, higher hydrocarbons, and heavy aromatics . Furthermore, the conventional method of steam cracking hydrocarbons in a cracker furnace is extremely energy intensive and is associated with high operating expenses and high capital expenditure. The process requires a huge consumption of fuel and maintenance of large, expensive and complex cracking furnaces to supply the heat. For example, the tubes / coils used in the furnaces are very expensive and have a limited lifetime.

[0010] Therefore, generally, it is desired to provide a process for the pyrolytic cracking of hydrocarbons that substantially reduces or avoids the production of carbon dioxide. It is also desired to provide a process for the pyrolytic cracking of hydrocarbons that substantially reduces or avoids the formation of NOx. It is further desired to provide a process for the pyrolytic cracking of hydrocarbons that substantially reduces or avoids the formation of coke and thus requires less reactor maintenance.

[0011] WO2023126103 discloses a process that meets these requirements as outlined above. WO2023126103 relates to a process for producing olefins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons in an autothermal reactor, said process comprising: pre-heating an oxygen containing stream and a hydrogen and / or methane containing stream outside the autothermal reactor; feeding the pre-heated oxygen containing stream and the pre-heated hydrogen and / or methane containing stream into a burner of the autothermal reactor; generating steam in a combustion zone of the autothermal reactor; pre-heating a feed stream containing hydrocarbons outside the autothermal reactor; feeding the pre-heated feed stream containing hydrocarbons into the autothermal reactor; mixing the steam generated in the combustion zone with the pre-heated feed stream containing hydrocarbons in a mixing and cracking zone of the autothermal reactor, by feeding the steam and the pre-heated feed stream containing hydrocarbons into the mixing and cracking zone from substantially opposite directions, and pyrolytically cracking the hydrocarbons to provide an effluent containing olefins.

[0012] Olefins as contained in the effluent coming from the process as disclosed in above-mentioned WO2023126103 comprise ethylene and acetylene. Of these olefins, ethylene is the desired product. A problem of the process of WO2023126103 is that the overall yield of ethylene is relatively low and that of acetylene is relatively high.

[0013] It is an object of the present invention to overcome or minimize one or more of the above problems.

[0014] It is a further object of the present invention to provide an alternative process for producing olefins using autothermal cracking with higher overall ethylene yield (based on the feed stream) .

[0015] Further, it is an objective of the present invention to provide a process for the pyrolytic cracking of hydrocarbons to olefins, which process is efficient and affordable, and in particular has relatively low operating expenses, relatively low capital expenditure and relatively low energy demand.

[0016] These and other objectives will become apparent from the disclosure provided herein.

[0017] Summary of the invention

[0018] Surprisingly, it was found that one or more of the above or other objectives can be achieved by subjecting at least a part of an effluent containing olefins, comprising ethylene and acetylene, as obtained in a process for producing olefins using autothermal cracking, to hydrogenation of acetylene in the gas phase in the presence of a heterogeneous catalyst at a temperature of at least 200 °C, thereby obtaining an ethylene-enriched stream and heat. Accordingly, the present invention relate s to a proces s for producing olef ins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons in an autothermal reactor , said proces s compris ing : pre-heating an oxygen containing stream and a hydrogen and / or methane containing stream outside the autothermal reactor ; feeding the pre-heated oxygen containing stream and the pre-heated hydrogen and / or methane containing stream into a burner of the autothermal reactor ; generating steam in a combustion zone of the autothermal reactor ; pre-heating a feed stream containing hydrocarbons outside the autothermal reactor ; feeding the pre-heated feed stream containing hydrocarbons into the autothermal reactor ; mixing the steam generated in the combustion zone with the pre-heated feed stream containing hydrocarbons in a mixing and cracking zone of the autothermal reactor , by feeding the steam and the pre-heated feed stream containing hydrocarbons into the mixing and cracking zone from substantially opposite directions , and pyrolytically cracking the hydrocarbons to provide an effluent containing olefins wherein the olefins comprise ethylene and acetylene ; subj ecting at least a part of the effluent containing olefins to hydrogenation of acetylene in the gas phase in the pre sence of a heterogeneous catalyst at a temperature of at lea st 200 ° C, thereby obtaining an ethylene-enriched stream and heat .

[0019] It has surpri singly been found according to the pre sent invention that an increased overall yield of ethylene can be obtained . The effluent provided by pyrolytically cracking the hydrocarbons in the process of the present invention, also contains hydrogen in addition to the olefins comprising ethylene and acetylene.

[0020] A further advantage of the process according to the present invention is that, as the hydrogenation of acetylene takes place at a relatively high temperature (of at least 200 °C) , no separation of the hydrogen- and acetylene-containing effluent is required before it is subjected to hydrogenation.

[0021] Brief description of the drawings

[0022] Figure 1 shows a schematic representation of an autothermal reactor for use in an embodiment of the process of the present invention.

[0023] Figure 2 shows a schematic representation of an alternative configuration of an autothermal reactor for use in an embodiment of the process of the present invention.

[0024] Figure 3 shows a schematic representation of another alternative configuration of an autothermal reactor for use in an embodiment of the process of the present invention.

[0025] Detailed description of the invention

[0026] The process of the present invention comprises multiple steps. In addition, said process may comprise one or more intermediate steps between consecutive steps. Further, said process may comprise one or more additional steps preceding the first step and / or following the last step. For example, in a case where said process comprises steps a) , b) and c) , said process may comprise one or more intermediate steps between steps a) and b) and between steps b) and c) . Further, said process may comprise one or more additional steps preceding step a) and / or following step c) .

[0027] Within the present specification, a phrase like "step y) comprises subjecting at least part of the stream resulting from step x) to" means ''step y) comprises subjecting part or all of the stream resulting from step x) to" or, similarly, ''step y) comprises partially or completely subjecting the stream resulting from step x) to". For example, the stream resulting from step x) may be split into one or more parts wherein at least one of these parts may be subjected to step y) . Further, for example, the stream resulting from step x) may be subjected to an intermediate step between steps x) and y) resulting in a further stream at least part of which may be subjected to step y) .

[0028] While the process of the present invention and the stream(s) or composition ( s ) used or produced in said process are described in terms of "comprising", "containing" or "including" one or more various described steps and components, respectively, they can also "consist essentially of" or "consist of" said one or more various described steps and components, respectively.

[0029] In the context of the present invention, in a case where a stream or composition comprises two or more components, these components are to be selected in an overall amount not to exceed 100%.

[0030] Further, where upper and lower limits are quoted for a property then a range of values defined by a combination of any of the upper limits with any of the lower limits is also implied .

[0031] In the present invention, the step of feeding the preheated oxygen containing stream and the pre-heated hydrogen and / or methane containing stream into the burner of the autothermal reactor may further comprise feeding a pre-heated temperature moderator into the burner of the autothermal reactor .

[0032] The pre-heated temperature moderator may comprise steam and / or carbon dioxide. The oxygen containing stream may be pre-heated to a temperature in the range of from about 200 °C to about 300 °C.

[0033] The hydrogen and / or methane containing stream may be preheated to a temperature in the range of from about 350 °C to about 650 °C.

[0034] The temperature moderator may be pre-heated to a temperature in the range of from about 350 °C to about 650 °C.

[0035] The temperature of the steam generated in the combustion zone may be in the range of from about 1400 °C to about 1900 °C, suitably about 1400 °C to about 1800 °C.

[0036] The steam generated in the combustion zone may flow into the mixing and cracking zone at a velocity in the range of from about 100 m / s to about 400 m / s .

[0037] The feed stream containing hydrocarbons may flow into the mixing and cracking zone at a velocity in the range of from about 50 m / s to about 300 m / s .

[0038] The feed stream containing hydrocarbons may be pre-heated outside the autothermal reactor to a temperature in the range of from about 200 °C to about 650 °C. Alternatively, the feed stream containing hydrocarbons pre-heated outside the reactor may be further heated inside the reactor to a temperature in the range of from about 200 °C to about 650 °C through indirect heat exchange.

[0039] The feed stream containing hydrocarbons may be further heated inside the reactor through indirect heat exchange between the effluent containing olefins and the feed stream containing hydrocarbons in an effluent zone of the reactor.

[0040] The feed stream containing hydrocarbons may comprise any one or more of ethane, propane, butane, liquefied petroleum gas (LPG) , naphtha, hydrowax, gas oil, bio-naphtha, biodiesel, plastics pyrolysis oil and renewable feedstocks. Methane may be added to the afore-mentioned feed stream containing hydrocarbons. The hydrocarbons from the feed stream containing hydrocarbons contain carbon and hydrogen atoms and may or may not additionally contain one or more heteroatoms. Said one or more heteroatoms may be oxygen, nitrogen, sulfur and / or a halogen, such as chlorine, suitably oxygen, nitrogen and / or a halogen.

[0041] In the present invention, the feed stream containing hydrocarbons may comprise waste plastics pyrolysis oil, preferably untreated waste plastics pyrolysis oil, more preferably untreated waste plastics pyrolysis oil containing heteroatom-containing contaminants. Waste plastics can be converted via cracking of the plastics, for example by pyrolysis, to a product stream containing hydrocarbons having a wide boiling range, commonly referred to as waste plastics pyrolysis oil. Such pyrolysis oil can in turn be further converted via steam cracking to high-value chemicals, including ethylene and propylene, which are monomers that can be used in making new plastics. Waste plastic that may be pyrolyzed to produce a feedstock pyrolysis oil for use in the present process may comprise heteroatom-containing plastics, such as polyvinyl chloride (PVC) , polyethylene terephthalate (PET) and polyurethane (PU) . Mixed waste plastic may be pyrolyzed that, in addition to heteroatom-free plastics, such as polyethylene (PE) and polypropylene (PP) , contains a relatively high amount of such heteroatom-containing plastics .

[0042] Further, in the present invention, the feed stream containing hydrocarbons may comprise a renewable feedstock, which is preferably a renewable feedstock containing oxygen and / or unsaturated bonds. Further, the renewable feedstock may be a treated renewable feedstock or an untreated renewable feedstock, preferably an untreated renewable feedstock, more preferably an untreated renewable feedstock containing oxygen and / or unsaturated bonds. Said treated renewable feedstock may have undergone a pre-treatment comprising hydrogenation.

[0043] As used herein, the term "renewable feedstock" means a feedstock from a renewable source. A renewable source may be animal, vegetable, microbial and / or bio-derived materials, including animal, vegetable, microbial and / or bio-derived waste materials. The renewable materials may be suitable for the production of fuels, fuel components and / or chemical feedstocks .

[0044] A preferred class of renewable materials which may be used as renewable feedstock in the process of the present invention are bio-renewable fats and oils comprising triglycerides, diglycerides, monoglycerides, free fatty acids, and / or fatty acid esters derived from bio-renewable fats and oils. Examples of fatty acid esters include, but are not limited to, fatty acid methyl esters and fatty acid ethyl esters. The bio-renewable fats and oils include both edible and non-edible fats and oils. Examples of bio-renewable fats and oils include, without limitation, algal oil, brown grease, canola oil, carinata oil, castor oil, coconut oil, colza oil, corn oil, cottonseed oil, fish oil, hempseed oil, jatropha oil, lard, linseed oil, milk fats, mustard oil, olive oil, palm oil, peanut oil, rapeseed oil, sewage sludge, soy oils, soybean oil, sunflower oil, pongamia oil, tall oil, tallow, used cooking oil, yellow grease, white grease, and combinations thereof.

[0045] Another preferred class of renewable materials which may be used as renewable feedstock in the process of the present invention are liquids derived from biomass liquefaction processes. Examples of such liquefaction processes include, but are not limited to, (hydro) pyrolysis, hydrothermal liquefaction, and combinations thereof. Renewable materials derived from biomass liquefaction processes may be used alone or in combination with bio-renewable fats and oils.

[0046] The renewable materials which may be used as renewable feedstock in the process of the present invention may contain impurities. Examples of such impurities include, but are not limited to, solids, iron, chloride, phosphorus, alkali metals, alkaline-earth metals, polyethylene, and unsaponif iable compounds. If required, these impurities can be removed from the renewable feedstock before being introduced to the process of the present invention. Methods to remove these impurities are known to the person skilled in the art.

[0047] The ethylene-enriched stream obtained by acetylene hydrogenation in the present invention may undergo further downstream processing and / or separation in a steam cracker unit .

[0048] The process of the present invention is advantageous in that a reduced amount of carbon dioxide or no or very little carbon dioxide is produced during the process. This is due to the heat for the cracking reaction being produced inside the reactor using feed streams that generate no or little carbon dioxide, for example when hydrogen and oxygen are fed to the burner of the reactor. Where oxygen and methane are fed to the burner, or oxygen and hydrogen and methane are fed to the burner, then some carbon dioxide may be produced, but the amount of carbon dioxide produced will still be lower than that produced using conventional pyrolytic cracking of hydrocarbons in a cracker furnace, which uses the external combustion of hydrogen and methane as the heat source.

[0049] The process of the present invention is also beneficial in that it avoids or substantially reduces the production of NOx. Where methane is fed to the burner (in combination with oxygen or in combination with oxygen and hydrogen ) , then some NOx may be produced, but the amount of NOx produced will still be lower than that produced using conventional pyrolytic cracking of hydrocarbons in a cracker furnace . The reduction or elimination of NOx production helps to reduce the cost of the olefins manufacture and minimize the release of this pollutant into the atmosphere .

[0050] A s ignif icant further benefit of the proces s of the invention i s that no or little coke is formed during cracking . S ince the formation of coke is substantially or altogether avoided , the reactor can run for much longer periods of time without interruption , and if any coke is formed, it can be eas ily and quickly removed from the reactor . In addition, since no or little coke is formed during the proces s of the present invention , there is no need to add sulphur to the hydrocarbon feed stream and thus there i s also no need for any treatment to remove H2S during the proces s .

[0051] The rapid and efficient mixing of the steam and the feed stream compri sing hydrocarbons in the mixing and cracking zone of the reactor enables high cracking temperatures and fast cracking time s that in turn leads to increased selectivities and high yields for the des ired olefins , particularly when compared to those obtained using conventional cracking of hydrocarbons in a cracker furnace .

[0052] In addition to the above , an important advantage of the pre sent proce s s is that an increased overall yield of ethylene can be obtained, due to the step in the present proces s wherein at least a part of the ef fluent containing olefins is subj ected to hydrogenation of acetylene in the gas pha se in the presence of a heterogeneous catalyst at a temperature of at lea st 200 ° C , thereby obtaining an ethylene-enriched stream and heat . Preferably, a part of the feed stream containing hydrocarbons, before pre-heating thereof, is combined with the effluent containing hydrogen, ethylene and acetylene. As a result, the latter effluent is quenched. This helps in further increasing the olefin yield and improves the heat recovery. Preferably, at most 50 wt . % of the feed stream containing hydrocarbons is combined with said effluent.

[0053] As the person skilled in the art is familiar with (selective) hydrogenation of acetylene, this is not discussed here in detail. A general description of hydrogenation of acetylene is discussed in for example US20130204056A1.

[0054] According to the present invention, the hydrogenation of acetylene is performed at temperatures of at least 200 °C, preferably at a temperature of from 250 to 500 °C. By using relatively high temperatures (of at least 200 °C) the hydrogenation of acetylene occurs whilst the acetylene is in the gas phase.

[0055] Generally, the hydrogenation of acetylene is performed at pressures in the range of from 1.0-10.0 bara, preferably 1.0- 5.0 bara .

[0056] The heterogeneous catalyst is not particularly limited, provided it can withstand the temperature of at least 200°C and is effective in selective hydrogenation of acetylene. More than one heterogeneous catalyst can be used at the same time. Suitable heterogenous catalysts are for example discussed in the above-mentioned US20130204056A1. Generally, the heterogenous catalysts may comprise a metal selected from Groups 8 to 10 of the Periodic Table and may include one or more promotor elements selected from Groups 1, 2, 11-14 of the Periodic Table. Preferably the heterogenous catalyst comprises a metal catalyst selected from the group consisting of Pd, PdAg, Pt, Cu, more preferably PdAg. The ethylene-enriched stream obtained in the hydrogenation step typically comprises 20-50 wt . % ethylene.

[0057] According to an especially preferred embodiment of the method according to the present invention, at least 70 wt.%, preferably at least 80 wt.%, more preferably at least 90 wt.% of the effluent containing hydrogen, ethylene and acetylene is subjected to the acetylene hydrogenation. Preferably, an intermediate separation of said effluent takes place between the outlet of the autothermal reactor and the inlet of the hydrogenation reactor. Such intermediate separation may comprise cooling down the effluent effecting condensation of steam in the effluent thereby separating off water from the effluent, which is also referred to as "quenching". Furthermore, said (quenched) effluent may be subjected to a heat exchange with effluent from the hydrogenation reactor thereby heating the (quenched) effluent before subjecting it to the acetylene hydrogenation.

[0058] Also, it is especially preferred according to the present invention that the hydrogenation of acetylene takes place in a hydrogenation reactor, which may comprise a multi-tubular reactor cooled by molten salt circulating around the tubes of the multi-tubular reactor, preferably in counter-current operation. The reactor may comprise an adiabatic reactor.

[0059] In the above-mentioned embodiment, the molten salt provides for the heat control of the reaction as taking place in the multi-tubular reactor. Preferably, the molten salt is circulating in counter-current mode around the tubes of the multi-tubular reactor (when compared to the fluid flow in the tubes of the reactor) .

[0060] Further, it is preferred that the heat obtained in the step of hydrogenation of acetylene is used to produce steam, preferably having a pressure in the range of from 10 to 80 bara, preferably from 15 to 50 bara. In case a multi-tubular reactor cooled by molten salt is used, then the heat can be removed from the molten salt in e . g . a separate heat exchanger .

[0061] It goes without saying that at least part of the heat as obtained in the acetylene hydrogenation step can be used elsewhere a s well ( instead of producing steam) , for example by integration with a separation section of a steam cracker and / or with a separation section of the autothermal reactor used in the present proce s s .

[0062] According to a particularly preferred embodiment of the proces s according to the present invention , the ethylene- enriched stream obtained in the acetylene hydrogenation step i s separated, thereby obtaining a hydrogen-depleted ethylene- enriched stream and a hydrogen-enriched stream .

[0063] The person skilled in the art will readily understand that the above-mentioned separation is not particularly limited and may involve the use of one or more separators such as membranes , pres sure swing absorbers and electrochemical separators .

[0064] The hydrogen-enriched stream may be used in any other ref inery or chemical operations and is preferably used in the hydrogen and / or methane containing stream a s fed to the autothermal reactor in the present proces s .

[0065] According to a further preferred embodiment of the proces s according to the present invention , a part of the ethylene-enriched stream obtained in the acetylene hydrogenation step is combined with ef fluent from the autothermal reactor and subj ected to said hydrogenation in step .

[0066] In general terms the present invention provides a method for the cracking of hydrocarbons to olefins in an autothermal reactor . For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the accompanying drawings, which are described in more detail below.

[0067] Figure 1 shows a representation of an autothermal reactor 10 for use in a process for producing olefins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons according to an embodiment of the present invention .

[0068] The autothermal reactor 10 comprises a burner 11, a combustion zone 12, a contraction zone 13, a mixing and cracking zone 14, and an effluent zone 16.

[0069] The burner 11 has an inlet section 18 through which an oxygen containing stream 20 and a hydrogen and / or methane containing stream 22 are fed into the burner 11. The inlet section 18 may comprise multiple inlets, one for each of the respective streams to be fed into the burner 11.

[0070] In the present invention, the hydrogen and / or methane containing stream preferably contains hydrogen. Further, said hydrogen containing stream may also contain methane. More preferably, said hydrogen containing stream consists of hydrogen. The amount of methane in the hydrogen and / or methane containing stream may be of from 0 to 15 vol.% or may be at most 10 vol.% or at most 5 vol.% or at most 1 vol.% or at most 0.5 vol.%, based on the total amount of hydrogen and methane. Further, said amount of methane in the hydrogen and / or methane containing stream may be at least 0.5 vol.% or at least 1.5 vol.% or at least 3 vol.%.

[0071] Hydrogen used in the hydrogen and / or methane containing stream 22, whether used alone or in combination with methane, can be any suitable source of hydrogen, including conventional hydrogen (so-called "grey" hydrogen) , hydrogen sustainably produced through renewable power electrolysis (so-called "green" hydrogen) , hydrogen produced from hydrocarbons in a process like steam methane reforming in combination with carbon capture and storage (so-called "blue" hydrogen) , or otherwise produced hydrogen.

[0072] Methane used in the hydrogen and / or methane containing stream 22, whether used alone or in combination with hydrogen, can be any suitable source of methane, including conventional methane as well as methane from renewable sources (so-called "green" methane) .

[0073] The oxygen containing stream 20 and the hydrogen and / or methane containing stream 22 are each pre-heated prior to being fed into the burner 11. Any known means for pre-heating the streams can be used. The oxygen containing stream 20 is typically pre-heated to a temperature in the range of from about 200 °C to about 300 °C. Suitably, the oxygen containing stream 20 can be pre-heated to a temperature of at least 200 °C, suitably at least 220 °C, suitably at least 240 °C. Suitably, the oxygen containing stream 20 can be pre-heated to a temperature of at most 300 °C, suitably at most 280 °C, suitably at most 260 °C. The hydrogen and / or methane containing stream 22 is typically pre-heated to a temperature in the range of from about 350 °C to about 650 °C. Suitably, the hydrogen and / or methane containing stream 22 can be preheated to a temperature of at least 350 °C, suitably at least 400 °C, suitably at least 450 °C. Suitably, the hydrogen and / or methane containing stream 22 can be pre-heated to a temperature of at most 650 °C, suitably at most 600 °C, suitably at most 550 °C. The temperature to which these two streams are pre-heated can be varied accordingly depending on the desired temperature of the steam 23 generated in the combustion zone 12.

[0074] Other components can be fed into the burner 11 in addition to the oxygen containing stream 20 and the hydrogen and / or methane containing stream 22. For example, a temperature moderator 21, such as steam and / or carbon dioxide, can be fed into the burner 11 to help regulate the temperature of the steam 23 that results from the combustion of oxygen and hydrogen, or oxygen and methane, or all three of oxygen, hydrogen and methane (when a mixture of hydrogen and methane is used in stream 22) in the combustion zone 12. The temperature of this additional temperature moderator 21, e.g. steam and / or carbon dioxide, can be varied accordingly depending on the desired temperature of the steam 23 generated in the combustion zone 12. Typically, the temperature moderator 21 (whether it be steam, carbon dioxide or a mixture of both, or indeed any other suitable temperature moderator) is pre-heated to a temperature in the range of from about 350 °C to about 650 °C before being fed into the burner 11. Suitably, the temperature moderator 21 can be pre-heated to a temperature of at least 350 °C, suitably at least 400 °C, suitably at least 450 °C. Suitably, the temperature moderator 21 can be pre-heated to a temperature of at most 650 °C, suitably at most 600 °C, suitably at most 550 °C. The temperature moderator 21 can be fed to the burner 11 alone or in combination with the oxygen containing stream 20 and / or the hydrogen and / or methane containing stream 22. In the embodiment shown in Figure 1, purely for simplicity purposes, the optional temperature moderator 21 is shown as being fed into the burner 11 separately to the oxygen containing stream 20 and the hydrogen and / or methane containing stream 22.

[0075] The addition of steam and / or carbon dioxide, or other inert gas, to the burner 11 can also help to prevent the oxygen and the hydrogen and / or methane from reacting in close vicinity of the burner inlet section 18. The oxygen and hydrogen, or the oxygen and methane, or the oxygen and hydrogen and methane (depending on the composition of the feed stream 22) combust in the combustion zone 12 leading to a high flame temperature and the formation of steam 23, substantially free of oxygen. Within the present specification, steam "substantially free of oxygen" means that the steam contains of from 0 to 10,000 parts per million of volume (ppmv) of oxygen or may contain oxygen in an amount of at most 5, 000 ppmv or at most 1,000 ppmv or at most 500 ppmv or at most 10 ppmv. In the present invention, such steam substantially free of oxygen may be provided by feeding hydrogen in an amount which is higher than the stoichiometric molar amount needed for the reaction of hydrogen with oxygen, for example 1-5% or 1-3% higher. The temperature of the steam 23 generated in the combustion zone 12 can vary depending on the type of hydrocarbon feedstock to be cracked. Typically, the temperature of the steam 23 generated in the combustion zone 12 is in the range of from about 1400 °C to about 1900 °C, suitably about 1400 °C to about 1800 °C, depending on the type of hydrocarbon feedstock to be cracked. Suitably, the temperature of the steam 23 generated in the combustion zone 12 can be at least 1400 °C, suitably at least 1450 °C, suitably at most 1900 °C, suitably at most 1800 °C, suitably at most 1750 °C. For example, where ethane is used as the hydrocarbon feedstock, the temperature of the steam 23 generated in the combustion zone 12 can suitably be in the range of from about 1650 °C to about 1750 °C.

[0076] This high-temperature steam 23, generated within the autothermal reactor 10, is the heat source that is used to effect the pyrolytic cracking of hydrocarbons in the process of the present invention. The generation of heat in this manner is advantageous over conventional pyrolytic cracking of hydrocarbons in a cracker furnace, using the external combustion of hydrogen and methane as the heat source , because no or very little carbon dioxide is produced when oxygen and hydrogen are fed to the burner 11 (without the pre sence of methane or other hydrocarbon being co-fed) . In case oxygen and methane are fed to the burner 11 , or oxygen and hydrogen and methane are fed to the burner 11 , then some carbon dioxide may be produced, but the amount of carbon dioxide produced will still be lower than that produced using conventional pyrolytic cracking of hydrocarbons in a cracker furnace .

[0077] The high-temperature steam 23 generated in the combustion zone 12 flows into the contraction zone 13 , which a s shown in Figure 1 is located below the combustion zone 12 . The contraction zone 13 i s narrower in width than the combustion zone 12 and narrows downwards along its length to ensure that the high-temperature steam 23 flows at a very high velocity downwards towards the mixing and cracking zone 14 of the reactor 10 .

[0078] A wide variety of hydrocarbon feedstocks can be used in the proces s of the present invention . The feed stream containing hydrocarbons 28 contains saturated hydrocarbons and may optionally contain unsaturated hydrocarbons . Further , before the feed stream containing hydrocarbons 28 i s subj ected to the proces s of the present invention , it may be gaseous or may be in liquid form . Suitably, the feed stream 28 may contain C2+ hydrocarbons . Suitably, the feed stream containing hydrocarbons 28 may include any one or more of ethane , propane , butane , liquefied petroleum gas (LPG) , naphtha , hydrowax and gas oil . Bio-derived and synthetic hydrocarbons can also be used, such as bio-naphtha , biodie sel , pla stics pyrolysi s oil and renewable feedstocks .

[0079] It is pos sible for some methane to be added to the hydrocarbon feed stream 28 . In this instance , the methane can be considered as a secondary hydrocarbon feedstock, with the above-mentioned hydrocarbons (e.g. C2+ hydrocarbons; or the ethane, propane, butane, liquefied petroleum gas (LPG) , naphtha, hydrowax, gas oil, bio-naphtha, bio-diesel, plastics pyrolysis oil and renewable feedstocks) being the primary hydrocarbon feedstock. The methane can be added simultaneously with the primary hydrocarbon feedstock (e.g. it can be mixed in with the primary hydrocarbon feedstock) , or it can be introduced into the reactor prior to introduction of the primary hydrocarbon feedstock. Typically, the optional additional methane constitutes a relatively small proportion of the total hydrocarbon feed stream 28.

[0080] The feed stream containing hydrocarbons 28 is pre-heated prior to being fed into the reactor 10. Any known means for pre-heating the feed stream can be used. The temperature to which the feed stream comprising hydrocarbons 28 is preheated depends partly on the type of hydrocarbon feedstock being used. It also depends on whether or not any further heating of the feed stream containing hydrocarbons 28 takes place inside the reactor 10 prior to contacting of the feed stream containing hydrocarbons 28 with the high-temperature steam 23 (also referred to herein as the "steam stream") in the mixing and cracking zone 14 (which is discussed in further detail below) . Ultimately, what is important is the temperature of the feed stream containing hydrocarbons 28 immediately before or as it contacts the steam stream 23 in the mixing and cracking zone 14. Typically, the temperature of the feed stream containing hydrocarbons 28 just before it contacts the steam 23 in the mixing and cracking zone 14 is in the range of from about 200 °C to about 650 °C, depending on the type of hydrocarbon feedstock being used. Suitably, the temperature of the feed stream containing hydrocarbons 28 just before it contacts the steam 23 in the mixing and cracking zone 14 can be at least 200 °C, suitably at least 250 °C, suitably at most 650 °C, suitably at most 600 °C. For example, where ethane is used as the hydrocarbon feedstock, the temperature of the feed stream containing ethane can suitably be in the range of from about 550 °C to about 650 °C. This may mean that the feed stream containing hydrocarbons 28 is pre-heated to the desired temperature (i.e. the temperature immediately before or just as it contacts the steam 23 in the mixing and cracking zone 14) , e.g. to a temperature in any of the afore-mentioned ranges, depending on the hydrocarbon feedstock being used, prior to being fed into the reactor 10, if no significant further heating of the feed stream containing hydrocarbons 28 takes place inside the reactor 10 prior to contacting of the feed stream containing hydrocarbons 28 with the steam stream 23 in the mixing and cracking zone 14. If, as discussed in further detail below and as per the embodiment of the invention shown in Figure 1, for example, further heating of the feed stream containing hydrocarbons 28 does take place inside the reactor 10 prior to contacting of the feed stream containing hydrocarbons 28 with the steam stream 23 in the mixing and cracking zone 14, then the feed stream containing hydrocarbons 28 can be pre-heated to a lower temperature than the desired temperature (i.e. the temperature immediately before or just as it contacts the steam 23 in the mixing and cracking zone 14) prior to being fed into the reactor 10, since it will be heated up further in the reactor 10 prior to mixing with the steam stream 23. The extent to which the feed stream containing hydrocarbons 28 is further heated inside in the reactor will depend on various factors, including the mechanism by which the feed stream containing hydrocarbons 28 is further heated (e.g. by indirect heat exchange) , the length of time for which it is exposed to additional heat and the type of hydrocarbon feedstock being used. For example, the additional heating inside the reactor may typically increase the temperature of the pre-heated feed stream containing hydrocarbons by between about 10 °C and about 200 °C. So, the feed stream containing hydrocarbons can typically be pre-heated outside the reactor to a temperature between about 10 °C and about 200 °C lower than the desired temperature of about 200 °C to about 650 °C when the feed stream containing hydrocarbons enters the mixing and cracking zone 14. In either scenario (i.e. whether there is any significant further heating of the hydrocarbon feedstock 28 in the reactor 10 or not) , the temperature of the pre-heated feed stream containing hydrocarbons 28 is lower than the temperature of the steam 23 generated in the combustion zone 12, both when it is fed into the reactor 10 and immediately before or as it contacts the steam 23 in the mixing and cracking zone 14.

[0081] The feed stream containing hydrocarbons 28 can be fed into the reactor 10 through inlet 30. In the reactor configuration shown in Figure 1, inlet 30, for simplicity reasons, is shown as a side-arm, whereas in practice alternative configurations of inlet and other means of introducing the hydrocarbon containing feed stream 28 into the reactor 10 are possible and included within the scope of the present invention. Also, in practice there may be more than one inlet or side-arm present to introduce the hydrocarbons 28 into the reactor 10. In Figure 1, the inlet 30 is depicted as being located beneath and to the side of the reactor 10. Figures 2 and 3 show alternative configurations of reactor 10, where the inlet 30 is shown as a single side-arm protruding from a side wall of the reactor 10. The location of the inlet can be any suitable location that allows the hydrocarbon containing feed stream 28 to be introduced into the reactor in a suitable manner so as to realise the advantage s of the present invention . In the reactor configuration shown in Figure 1 , the feed stream containing hydrocarbons 28 , once introduced through inlet 30 , typically by high speed inj ection , flows upwards towards the mixing and cracking zone 14 through a narrow inner tube or lance 32 . The narrow width of the lance 32 ensure s the feed stream containing hydrocarbons 28 flows at high velocity, typically at a velocity in the range of f rom about 50 m / s to 300 m / s , towards the mixing and cracking zone 14 of the reactor 10 . In the reactor configuration shown in Figure 1 , the lance 32 extends from beneath the reactor , upwards through the effluent zone 16 , and terminate s at the mixing and cracking zone 14 .

[0082] In the mixing and cracking zone 14 , the steam stream 23 f rom the contraction zone 13 is contacted with the feed stream containing hydrocarbons 28 from the lance 32 and the two streams mix . Both streams are flowing at high velocity and thus mixing occurs rapidly, although preferably the steam stream 23 i s moving at a higher velocity than the feed stream containing hydrocarbons 28 . Typically, the steam stream 23 is f lowing at a velocity in the range of from about 100 m / s to about 400 m / s , suitably in the range f rom about 150 to about 300 m / s . Suitably, the steam stream 23 is f lowing at a velocity in the range of from about 50 m / s to about 150 m / s higher than that of the feed stream containing hydrocarbons 28 .

[0083] In the reactor configuration shown in Figure 1 , the use of the lance 32 ensures that the feed stream containing hydrocarbons 28 flows upwards towards the mixing and cracking zone 14 , such that the steam stream 23 and the feed stream containing hydrocarbons 28 are f lowing towards the mixing and cracking zone 14 in substantially opposite directions , i . e . they are flowing counter-currently, and that they collide and contact each other substantially head-on in the mixing and cracking zone 14. This substantially opposite or countercurrent high-velocity flow of the two streams, i.e. the steam stream 23 and the feed stream containing hydrocarbons 28, has been found to lead to extremely fast and efficient mixing of the two streams. For example, the opposite flow of the two high-velocity streams has been found to lead to much faster and more efficient mixing of the two streams compared to when the feed stream containing hydrocarbons 28 enters the mixing and cracking zone 14 and is contacted with the steam stream 23 perpendicular to the flow of the steam stream 23, e.g. in a configuration where the inlet for the entry of the feed stream containing hydrocarbons into the reactor leads directly into the mixing and cracking zone without the use of an upwardly extending narrow tube or lance (see Example 2) .

[0084] The steam stream 23 and the feed stream containing hydrocarbons 28 can be directly opposite streams moving towards one another and fed into the mixing and cracking zone 14 to contact and mix with one another, or they can be substantially opposite streams, i.e. the streams can be slightly off-set and do not have to be fed into the mixing and cracking zone 14 from precisely opposite directions. Thus, within the present specification, "substantially opposite directions" for the steam and the pre-heated feed stream containing hydrocarbons when feeding into the mixing and cracking zone, covers both (i) directly or precisely opposite directions, that is to say 100% opposite directions (directions with a difference of 180°) , and (ii) directions which deviate from said 100% opposite directions to some extent. In the present invention, the deviation from said 100% opposite directions may be of from 0 to 20° or may be at most 15 ° or at most 10 ° or at most 5 ° or at most 3 ° or at most 1 ° .

[0085] The rapid mixing due to the opposing or counter-current f low of the two high-velocity streams has the benefit of avoiding back-mixing of the feed stream containing hydrocarbons 28 in the steam 23 in the mixing and cracking zone 14 . Such back-mixing can mean that the hydrocarbon cracks for too long at high temperatures , causing a build-up of coke and other undesired reactions .

[0086] Optionally, steam can be added to the feed stream containing hydrocarbons 28 to help avoid coke formation in the lance 32 and / or to help increase the hydrocarbon to olefin conversion after mixing .

[0087] Optionally, there can be a device present in the reactor 10 that cause s the steam 23 to swirl in the contraction zone 13 to as sist with rapid and efficient mixing of the two opposing streams . Also , optionally, there can be a noz zle or multiple outlets ( see Figure 3 ) present at the tip of the lance ( at the mixing and cracking zone 14 ) to change the local inj ection velocity of the hydrocarbon feed stream 28 as it enters the mixing and cracking zone 14 .

[0088] Mixing of the high-temperature steam stream 23 (which is typically at a temperature in the range of from about 1400 ° C to about 1900 ° C , suitably about 1400 ° C to about 1800 ° C , when it reaches the mixing and cracking zone 14 ) with the cooler feed stream containing hydrocarbons 28 cause s the feed steam containing hydrocarbons 28 to heat up . Thus , the high- temperature steam 23 is the heat source that is used to effect the pyrolytic cracking of the hydrocarbons in the proces s of the pre sent invention .

[0089] The cracking temperatures , resulting f rom the rapid mixing of the high-temperature steam 23 and the cooler feed stream containing hydrocarbons 28 , in the proces s of the present invention for producing olefins from a feed stream containing hydrocarbons are much higher than the cracking temperatures used in conventional steam cracking in a cracker furnace. Typically, the cracking temperatures are up to a few hundred degrees higher (for example, about 200 °C to about 400 °C higher) than conventional steam cracking in a cracker furnace, which typically takes place at around 800-850 °C. Thus, in the present invention, the cracking temperature in the mixing and cracking zone may be of from 1,000 to 1,250 °C. In the present invention, the pyrolytic cracking in the mixing and cracking zone of the autothermal reactor is preferably carried out without using a catalyst.

[0090] The temperature of the steam 23 output from the combustion zone 12 and the temperature of the feed stream containing hydrocarbons 28 when it reaches the mixing and cracking zone 14 are optimised and selected so as to achieve the desired cracking temperatures for the chosen hydrocarbon feedstock .

[0091] The cracking times in the process of the present invention for producing olefins from a feed stream containing hydrocarbons are much shorter than the cracking times typically observed in conventional steam cracking in a cracker furnace. Typically, the cracking times using the process of the present invention are in the range of from about 1 millisecond (ms) to about 20 milliseconds (ms) , depending on the hydrocarbon feedstock to be cracked, so about two orders of magnitude lower than the cracking times typically observed in conventional steam cracking in a cracker furnace.

[0092] The high cracking temperatures and the short cracking times achieved using the process of the present invention surprisingly provide better yields and selectivities for the desired olefins compared to conventional steam cracking of hydrocarbons in a cracker furnace . Furthermore , no or very little coke i s produced at such high cracking temperatures and short cracking times .

[0093] The mixing of the feed stream containing hydrocarbons 28 and the steam stream 23 in the mixing and cracking zone 14 is so rapid and thorough that mixing and cracking largely occur s imultaneously . As such , a maj ority of the hydrocarbons crack whilst in the mixing and cracking zone 14 , although some cracking may also take place in the ef fluent zone 16 ( so- called "after-cracking" ) .

[0094] In the reactor configuration shown in Figure 1 , the eff luent 34 containing olefins , i . e . the ef fluent stream containing the cracked products , flows downwards through the eff luent zone 16 of the reactor 10 around the out side of the lance 32 .

[0095] Thi s exemplif ied counter-current flow arrangement not only provides for the feed stream containing hydrocarbons 28 and the steam stream 23 to collide and meet a s substantially opposing streams and mix head-on in the mixing and cracking zone 14 , but it al so allows for indirect heat-exchange to take place between the cooler feed stream containing hydrocarbons 28 flowing upwards through the lance 32 and the resultant eff luent 34 flowing downwards around the outside of the lance 32 in the effluent zone 16 . The resultant effluent 34 flowing downwards around the outside of the lance 32 is at a higher temperature than the feed stream containing hydrocarbons 28 inside the lance 32 and cools as it flows downwards towards the base of the reactor 10 . Any remaining hydrocarbons being cracked in the effluent zone 16 will also be at a higher temperature than the feed stream containing hydrocarbons 28 inside the lance 32 . The temperature at which the cracked effluent 34 containing the de sired olef in products leaves the effluent zone 16 depends somewhat on the hydrocarbon feedstock used . Typically, the ef fluent 34 leaves the effluent zone 16 at a temperature of around 800 ° C . As dis cus sed earlier , when such a hydrocarbon inj ection arrangement a s shown in Figure 1 is present in the reactor 10 , the feed stream containing hydrocarbons 28 advantageous ly only needs to be pre-heated outside the reactor 10 to a temperature that i s lower than the des ired target temperature of the feed stream containing hydrocarbons 28 as it reaches the mixing and cracking zone 14 , because heat trans fer will take place along the length of the lance 32 f rom the warmer eff luent 34 containing the desired olefin product s flowing downwards out side the lance 32 to the cooler feed stream containing hydrocarbons 28 flowing upwards inside the lance 32 . Lower pre-heating temperatures for the feed stock containing hydrocarbons 28 reduces the ri s k of unde sired cracking in a pre-heater and al so reduces the cost of heating the feed stream containing hydrocarbons 28 outside the reactor 10 prior to introducing it into the reactor 10 . The feed stream containing hydrocarbons 28 flowing upwards through the lance 32 also helps to rapidly cool the effluent 34 in the eff luent zone 16 .

[0096] A longer lance 32 will provide for increa sed indirect heat transfer between the cooler feed stock containing hydrocarbons 28 flowing upwards in the lance 32 and the eff luent 34 f lowing downwards around the lance 32 . Although in practice there may be a limit on the maximum des irable length of the lance depending on engineering and construction considerations , such as vibration of the lance . Supports can be used to stabili se the lance to reduce / prevent vibration of the lance .

[0097] The reactor configuration shown in Figure 2 has a somewhat shorter lance than that shown in Figure 1 , and the reactor configuration shown in Figure 3 has a much shorter lance than that shown in Figure 1. In the configuration shown in Figure 3, there will be much less heat transfer than in the configuration shown in Figure 1 as the lance does not extend the full length of the effluent zone 16.

[0098] As discussed earlier, the indirect heat-exchange flow arrangement shown in Figures 1 to 3 is not essential to the process of the present invention, but it is a beneficial feature that arises due to the f eeding / in j ection of hydrocarbons 28 through the lance 32 to create opposing streams (i.e. the steam stream 23 and the feed stream containing hydrocarbons 28) in the mixing and cracking zone 14.

[0099] Optionally, there may be a separate heat exchanger 35 present in the reactor. Typically, such a separate heat exchanger would be present in the effluent zone 16 of the reactor 10. The heat exchanger 35 may be used to pre-heat the feed stream containing hydrocarbons 28 outside the autothermal reactor. Such a heat exchanger also may be used to pre-heat the oxygen containing stream 20 and / or the hydrogen and / or methane containing stream 22 before they enter the burner 11.

[0100] From the effluent zone 16, an effluent 34 is obtained that comprises olefins which include ethylene and acetylene and which may include one or more of propylene, butylenes and butadiene, and hydrogen, water and carbon dioxide, and that may comprise aromatics (as produced in the cracking process) which may include one or more of benzene, toluene and xylene. The specific products obtained depend on the composition of the hydrocarbon feed stream, the hydrocarbon-to-steam ratio, the cracking temperature and the cracking time.

[0101] The invention is further illustrated by the following Example .

[0102] Example Hydrogenation of acetylene was carried out in a quartz reactor with an internal diameter of 5 mm and a wall thickness of 5 mm. A gas mixture containing ethylene, acetylene and hydrogen was pre-heated to 240 °C and fed into the reactor loaded with heterogeneous catalyst at a pressure of 2 bara. The gas mixture contained the following components in the following concentrations:

[0103] Acetylene 10.2%

[0104] Ethylene 6.0%

[0105] Hydrogen 51.3%

[0106] Methane 18.7%

[0107] Nitrogen 13.7%

[0108] The catalyst, which contained Pd and Ag deposited on an alumina support, was placed inside the reactor as a shallow catalyst bed with a height of 3 mm and a diameter of 5 mm. The flow rate of the gas mixture was 9 L / hr, resulting in a gas hourly space velocity of 142,000 L / L / h.

[0109] During the experiment which had a runtime of 7 hours, the conversion of acetylene was constant and was 100%. Furthermore, the selectivity to ethylene was advantageously high, around 93%. The selectivity to ethane was only about 3%. Thus, this Example shows that acetylene is selectively hydrogenated into additional ethylene, and that the presence of ethylene in the feed stream does not lead to formation of a significant amount of ethane.

Claims

C L A I M S1 . A proces s for producing olefins from a feed stream containing hydrocarbons by pyrolytic cracking of the hydrocarbons in an autothermal reactor , said proces s comprising : pre-heating an oxygen containing stream and a hydrogen and / or methane containing stream outside the autothermal reactor ; feeding the pre-heated oxygen containing stream and the pre-heated hydrogen and / or methane containing stream into a burner of the autothermal reactor ; generating steam in a combustion zone of the autothermal reactor ; pre-heating a feed stream containing hydrocarbons outside the autothermal reactor ; feeding the pre-heated feed stream containing hydrocarbons into the autothermal reactor ; mixing the steam generated in the combustion zone with the pre-heated feed stream containing hydrocarbons in a mixing and cracking zone of the autothermal reactor , by feeding the steam and the pre-heated feed stream containing hydrocarbons into the mixing and cracking zone from substantially opposite directions , and pyrolytically cracking the hydrocarbons to provide an effluent containing olefins wherein the olefins comprise ethylene and acetylene ; subj ecting at least a part of the effluent containing olefins to hydrogenation of acetylene in the gas phase in the pre sence of a heterogeneous catalyst at a temperature of at lea st 200 ° C, thereby obtaining an ethylene-enriched stream and heat .

2. The process according to claim 1, wherein the heat obtained in the hydrogenation of acetylene is used to produce steam, preferably having a pressure in the range of from 10 to 80 bara, preferably from 15 to 50 bara.

3. The process according to claim 1 or 2, wherein the pre-heated temperature moderator comprises steam and / or carbon dioxide.

4. The process according to any one of claims 1 to 3, wherein the oxygen containing stream and the temperature moderator containing stream are pre-heated electrically.

5. The process according to any one of claims 1 to 4, wherein the hydrogen and / or methane containing stream is preheated to a temperature in the range of from about 350 °C to about 650 °C.

6. The process according to any one of claims 1 to 5, wherein the temperature of the steam generated in the combustion zone is in the range of from about 1400 °C to about 1900 °C.

7. The process according to any one of claims 1 to 6, wherein the steam generated in the combustion zone flows into the mixing and cracking zone at a velocity in the range of from about 100 m / s to about 400 m / s .

8. The process according to any one of claims 1 to 7, wherein the feed stream containing hydrocarbons flows into the mixing and cracking zone at a velocity in the range of from about 50 m / s to about 300 m / s .

9. The process according to any one of claims 1 to 8, wherein the feed stream containing hydrocarbons is pre-heated outside the autothermal reactor to a temperature in the range of from about 200 °C to about 65 any one of claims 1 to 80 °C.

10. The process according to any one of claims 1 to 9, wherein the feed stream containing hydrocarbons pre-heated outside the reactor is further heated inside the reactor to a temperature in the range of from about 200 °C to about 650 °C through indirect heat exchange.

11. The process according to claim 10, wherein the feed stream containing hydrocarbons is further heated inside the reactor through indirect heat exchange between the effluent containing olefins and the feed stream containing hydrocarbons in an effluent zone of the reactor.

12. The process according to any one of claims 1 to 11, wherein the feed stream containing hydrocarbons comprises any one or more of ethane, propane, butane, liquefied petroleum gas (LPG) , naphtha, hydrowax, gas oil, bio-naphtha, biodiesel, plastics pyrolysis oil and renewable feedstocks.

13. The process according to claim 12, further comprising adding methane to the feed stream containing hydrocarbons.

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