Fuel production systems and methods

Abstract

Disclosed herein is a fuel production system comprising a Fischer-Tropsch (FT) reactor system and one or more supply conduits configured to supply a carbon source and H2 to the FT reactor system; the carbon source includes both CO and CO2 having a molar CO2 / CO ratio that is at least 0.10, the supply of CO and H2 to the FT reactor system is a supply of syngas, and the FT reactor system is configured to produce a fuel in response to the received syngas.

Description

[Technical field]

[0001] The present invention relates to the production of hydrocarbons. Embodiments include producing hydrocarbons from a carbon source that includes both carbon dioxide and carbon monoxide. Embodiments include adding hydrogen to the carbon source and producing the hydrocarbons by the Fischer-Tropsch process. [Background technology]

[0002] It is generally assumed that the greenhouse effect and the climate on Earth are closely linked to anthropogenic emissions of CO2. These emissions are formed mainly by the combustion of fossil coal and hydrocarbons, i.e. for heating, generating electricity, as well as by their use in internal combustion engines in vehicles. The desired goal is to reduce the release of CO2 into the atmosphere.

[0003] It is a known technique to reduce the emission of CO2 from the combustion of hydrocarbons by reforming and conversion technologies to prepare a mixture consisting of hydrogen and carbon dioxide. These components can be separated and the carbon dioxide is deposited after compression to the desired pressure, after the hydrogen is used for energy generation, heating or different types of transportation. However, such techniques are not in operation today, at least in any significant volume.

[0004] An alternative technology is to utilise hydrogen and CO to produce fuels, waxes and other hydrocarbons for the current market, particularly diesel for transportation vehicles and waxes for a variety of applications including adhesives.

[0005] There is a general need to improve known techniques for the production of hydrocarbons. Summary of the Invention

[0006] Aspects of the invention are set out in the accompanying independent claims. Optional aspects are set out in the dependent claims. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic block diagram of at least some of the components of a fuel production system according to one embodiment; [Diagram 2] 1 is a table showing different compositions (mol %) of carbon sources; [Diagram 3] FIG. 1 shows mole fractions and CO2 / CO ratios of the feed to the FT reactor in a system according to one embodiment; [Figure 4] FIG. 1 shows mole fractions in dry tail gas in a system according to one embodiment; [Diagram 5] 1 is a schematic block diagram of at least some of the components of a fuel power generation system according to one embodiment; [Figure 6] 1 is a schematic block diagram of at least some of the components of a fuel power generation system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The embodiments relate to techniques for producing fuels from carbon sources, including both carbon monoxide (CO) and carbon dioxide (CO2), and intentionally produced hydrogen. Such carbon sources may be off-gas from the production of iron or ferroalloys. Alternatively, the carbon source may be gas obtained from the gasification of biomass, or gas produced by reforming of natural gas at temperatures lower than standard practice.

[0009] Embodiments provide a fuel production system that produces synthetic hydrocarbons to replace fossil fuels. The synthetic fuels produced can include kerosene (jet fuel), diesel, and gasoline. Synthetic hydrocarbons can be produced from synthesis gas, a mixture of hydrogen (H2) and carbon monoxide (CO).

[0010] It is known to produce the CO component of synthesis gas using the reverse (d) water-gas shift reaction (rWGS / RWGS), where the main carbon feed to the system is CO2. CO2 is converted to CO in an rWGS reactor. The produced CO can then be mixed with hydrogen to produce synthesis gas that can be fed to a Fischer-Tropsch reactor. However, due to a number of difficult technical problems, a suitable rWGS reactor is not yet commercially available.

[0011] Embodiments advantageously produce synthesis gas without first requiring an rWGS reactor to convert the main carbon feed to the system to CO. Systems according to embodiments can use a combination of a Fischer-Tropsch reactor configured to operate with a very high proportion of inert gases (CO2 and N2) and a CO generation system configured to convert the off-gas from the Fischer-Tropsch reactor CO with a conventional POX reactor.

[0012] In embodiments, the percentage of inerts (i.e., gas that does not substantially react) in the Fischer-Tropsch reactor and / or CO generation system is typically 60% and can even be as high as 80%. This allows for the utilization of a very wide range of carbon sources. In particular, the process can receive blast furnace gas from ferromanganese and ferrosilicon production plants.

[0013] A fuel production system according to an embodiment includes a Fischer-Tropsch (FT) reactor. The feed to the FT reactor includes syngas (synthesis gas). For FT reactors with cobalt catalysts, the reactive components are H2 and CO, with the H2 / CO ratio preferably being greater than 1 and less than 2.5. Additionally, inert components may be present in the feed to the FT reactor in addition to the synthesis gas. These may include methane, CO2, nitrogen and moisture. Inert components are generally considered undesirable because they contribute to larger than required process units: especially since most FT schemes have a recycle stream(s) to ensure an overall high conversion of the carbon-containing feed to the desired hydrocarbon products. Thus, recycling results in the accumulation of inert components. Water can be removed by condensing it at the appropriate place in the process, but nitrogen needs to be removed from the system through the purge gas. Thus, in order to have a suitable process, there is an upper limit on the concentration of nitrogen (and other inert gases, such as the noble gases) in the feed gas.

[0014] Regarding the carbon source for producing CO in the syngas, this is most commonly natural gas, essentially methane, or coal, but can also be various biomasses. They are converted to produce syngas in a reformer or gasifier. Apart from being inert in the FT reaction, methane is actually a by-product of the reaction; typically with a carbon selectivity of 5-15%. In addition, a small amount of methane (called methane slip) is obtained that is not converted in the reformer. Therefore, there is a way to remove the methane in the process by having a reformer. This can be a reformer used to convert natural gas, or a dedicated reformer used to reform part of the recycle gas, i.e. a tail gas reformer. The recycle gas from the FT reactor, i.e. the tail gas, further contains other inerts that are not condensed as part of the product, unconverted syngas, and some light hydrocarbons. Part of the tail gas is purged and / or used in a fired heater that heats the feed stream to maximize energy efficiency.

[0015] Like methane, CO2 is inert in the FT reaction, but can also constitute a carbon source. When fed to a reformer, this process is called the dry reforming process, a process that requires large amounts of additional energy. CO2 can also be converted to CO via the reverse gas shift reaction; RWGS: CO2+ H2→ CO + H2O The reaction proceeds at high temperatures with the addition of hydrogen, the higher the temperature the greater the conversion. With CO2 as the only or significant part of the feed, hydrogen can be added from another source to ensure the H2 / CO ratio is appropriate. Such hydrogen sources are, for example, steam reforming of natural gas, or electrolysis of water.

[0016] Methods have been developed that use CO2 as a feedstock together with hydrogen from electrolysis. Often, they include a tail gas reformer and a RWGS reactor; at least a RWGS cross section. The inventors have discovered that the FT process can be simplified if a carbon source can be found that contains both CO and CO2 from the beginning. Indeed, a suitable such source is for example the off-gas from a blast furnace, when iron ore is reduced in the furnace by coke. Blast furnaces are also used to make ferroalloys such as ferromanganese and ferrosilicon. Other techniques include the electric arc furnace and the direct carbothermal reaction.

[0017] 1 is a schematic block diagram of at least some of the components of a fuel production system according to one embodiment. The system components can include a CO production system 1, a scrubbing section 2, a Fischer-Tropsch (FT) reactor 3, and a separation system 4.

[0018] Stream 32 is the input feed conduit. The fluid in stream 32 is the carbon, i.e., carbon source, that is fed to the system according to one embodiment. The liquid in stream 32 can contain both CO2 and CO. Stream 32 bypasses the CO generation system 1 and can be the input to the FT reactor 3. Depending on the purity and water content of the carbon source, stream 32 can alternatively or additionally be input to the wash section 2.

[0019] The carbon source may be of a particular purity and may have been purified by additional means not shown in Figure 1, for example to remove traces of sulfur. The carbon source may also contain an amount of nitrogen, which may be significant, and may be purged through output stream 43.

[0020] The CO production system 1 may be a system including a single reactor or multiple reactors. The CO production system 1 may include a partial oxidation (POX) reactor and / or a reformer.

[0021] Hydrogen may be supplied to the CO2 generation system 1 and the FT reactor 3 through line 12, which is a fluid supply conduit. The amount of hydrogen supplied to the CO2 generation system 1 may be less than the amount of hydrogen supplied directly to the FT reactor 3. The hydrogen in line 12 may be supplied from any source, such as, for example, that produced by electrolysis of water. The process units 1, 2, 3, and 4 may be operated at high pressures, typically in the range of 10 to 60 bar, preferably 25 to 40 bar. Thus, both the hydrogen and carbon source feed streams in the respective conduits lines 12 and stream 32 may be pressurized to the operating pressure before entering the system. The process units 1, 2, 3, and 4 may be operated at the same pressure or at different pressures.

[0022] Stream 11 is a fluid conduit that may include a supply of oxygen to the system. The CO2 generation system 1 may be fed by oxygen through stream 11, hydrogen through stream 12, and a recycle stream 45 of a portion of the tail gas (described in more detail below). The system may include an output conduit for the CO2 generation system 1. The output conduit may include a fluid stream 13. The fluid stream 13 may include reformed gas produced in the CO2 generation system 1. The liquid stream 13 may include a significant amount of synthesis gas (i.e., CO and hydrogen) in addition to steam, unconverted CO2, residual methane, and nitrogen that may be contained in the carbon-rich feed stream 32. The CO2 generation system 1 may only rely on carbon from the tail gas to produce CO. The amount of carbon fed to the CO2 generation system 1 may be substantially less than the amount of carbon in the carbon source, i.e., in stream 32.

[0023] Before entering the Fischer-Tropsch reactor 3, the synthesis gas in fluid stream 13 can be cooled by a cooler (not shown in FIG. 1) and fed to the washing section 2 for washing and / or conditioning. In particular, in the washing section 2, water can be knocked out of the fluid stream 13 and leave the system in an output conduit carrying the fluid stream 21. The synthesis gas can also be washed to remove impurities, in particular because the CO-based FT catalyst can be very sensitive to certain impurities. The washing section 2 has a main output conduit configured to feed at least the synthesis gas to the fluid stream 31. The synthesis gas for the FT synthesis in the FT reactor 3 enters the FT reactor 3 through the fluid stream 31. The fluid stream 31 can also contain the recycled unconverted gas in the fluid stream 44 and the hydrogen fed by the fluid stream 12.

[0024] The recycle gas in fluid stream 44 is a portion of the tail gas, which may include unconverted synthesis gas as well as a portion of the product light gas, which contains primarily methane, but also CO2, light hydrocarbons, oxygenates, and variable amounts of nitrogen.

[0025] The FT reactor has an output conduit that supports a fluid stream 33. The fluid stream 33 includes the FT product produced in the FT reactor 3. The fluid stream 33 may also include unconverted synthesis gas. The fluid stream 33 may include two substreams, a gas stream and a liquid stream. Although only one FT reactor 3 is shown in FIG. 1, embodiments may use a single FT reactor 3 or a FT reactor system having multiple FT reactors 3 arranged in parallel and / or series with each other. For example, there may be a series arrangement of FT reactors 3 with hydrogen fed and / or a water removal step between adjacent FT reactors 3.

[0026] Fluid stream 33 flows into separation system 4. Separation system 4 shown in Figure 1 is simplified for clarity. Embodiments include implementing any of a number of known techniques for FT product separation, processing, and upgrading of fluid stream 33.

[0027] Separation system 4 may include separate systems for separately processing the gaseous and liquid components of fluid stream 33. Separation system 4 may include one or more output conduits for supporting liquid stream 42. Liquid stream 42 may include liquid fuel that is the primary intended product of the fuel production system. Liquid stream 42 may be output from the system and may optionally undergo stabilization and light and / or deep upgrading, such as hydrotreating. Liquid stream 42 is output from the system for storage and transportation.

[0028] The gaseous components of fluid stream 33 may be cooled in a three-phase separator. The lower part contains water produced by the FT reaction, which may be output from the system in a conduit carrying fluid stream 41. Liquid hydrocarbons lighter than the primary liquid output from the FT reactor 3 may also be obtained and may be stored and treated separately from the primary liquid from the FT reactor 3 in stream 42.

[0029] The remaining gas output from the separation system 4 is referred to as tail gas and is supported in the output conduit of the separation system 4. The tail gas may include unconverted synthesis gas, produced light hydrocarbons, and CO2. The embodiments may increase carbon utilization efficiency by converting at least a portion of the CO2 and gaseous hydrocarbons in the tail gas to CO for use in the FT reactor 3. This conversion is carried out in the CO generation system 1. The embodiments may also provide high CO conversion in the FT-reactor loop in the system. The embodiments may also purge nitrogen and other inert components from the system.

[0030] Thus, the tail gas can be split into three portions in separate fluid streams: a purge gas 43 stream, a syngas recycle 44 that is fed back to the FT reactor 3 in an internal recycle loop, and an external recycle 45 that is fed back to the CO production system 1.

[0031] Each aspect of the above-described system according to the embodiment will now be described in more detail.

[0032] As mentioned above, hydrogen is supplied to the system via fluid stream 12. Hydrogen may be produced by a number of known methods. One such method is electrolysis of water. Hydrogen has gained traction in the transportation sector as a fuel for fuel cells, and fueling stations for transportation vehicles have been deployed in several parts of the world, particularly in the United States, Europe, and Japan. In fact, all of these fueling stations are based on hydrogen, which is made by splitting water electrolytically and compressing the hydrogen, typically to 700 bar. Liquid hydrogen is being considered for heavier transportation such as ships and trains. Power for the electrolysis can be obtained from renewable energy sources such as wind, hydro, and photovoltaic solar cells. Other techniques such as plasma cracking, direct catalytic water cracking, and high temperature water cracking are being explored. Good hydrogen can also be obtained from the reforming of natural gas and subsequent storage of the CO2 in a reservoir.

[0033] There are several types of electrolysis available, the most common being alkaline electrolysis. Other methods include polymer electrolyte membrane electrolysis, carbonate electrolysis, and solid oxide electrolysis. An alkaline electrolysis cell has two electrodes separated by a diaphragm and operating in an alkaline solution of potassium hydroxide or sodium hydroxide. The diaphragm facilitates the transport of hydroxide ions from one electrode to the other and serves to separate the generated hydrogen and oxygen gases. The embodiments do not depend on a particular method for producing hydrogen, and the embodiments include hydrogen in the fluid stream 12 sourced from any type of hydrogen source. However, hydrogen production methods having a low carbon footprint are preferred.

[0034] Carbon dioxide is available in large quantities, specifically, currently present in the Earth's atmosphere at about 410 ppm, which is steadily increasing. Sorbents have been installed to capture CO2 from the atmosphere for use in small greenhouses. Another source of CO2 is from biomass; this can be through combustion or fermentation, or through photochemical or chemical processes. Such CO2 is not considered to contribute to the greenhouse effect or global warming. CO2 is also readily available from several industrial processes, typically from combustion heaters or combustion turbines, but also as a major by-product of ammonia synthesis, hydrogen production, and cement production, among others. Large amounts of CO2 are generated from municipal solid waste piles and from distributed heat sources. However, the main sources of man-made CO2 are the use of gas, oil, and coal in power generation and the transportation sector. The embodiments do not depend on the specific CO2 source, and the CO2 in the liquid stream 32 can come from any CO2 source. However, a CO2 source with a low overall carbon footprint is preferred.

[0035] The conversion of CO2 and hydrogen to liquid hydrocarbons according to embodiments can be based on a three-step process including: 1) producing synthesis gas (syngas) essentially comprising hydrogen and CO; 2) synthesis gas conversion by Fischer-Tropsch (FT) synthesis; 3) upgrading of the raw FT products (wax and naphtha / distillates) to end products such as naphtha, kerosene, diesel or other products, e.g. lubricant oil basestocks. Wax is also a valuable product in itself. Upgrading typically uses hydrogen in hydrogenation, hydrocracking and / or isomerization processes. Such upgrading stabilizes the product; converts olefins to alkanes and removes generated oxygenates; adjusts chain length to the desired region; isomerizes alkanes to improve the low temperature properties of the product. Upgrading may be performed in whole or in part at the production site or the product may be transported to a dedicated refinery.

[0036] FT synthesis can be classified into high temperature FT (HTFT) process operating at 330-370 °C and low temperature FT (LTFT) process operating at 210-260 °C. The former gives products mainly in the naphtha range, which contain linear and branched olefins with high aromatics and oxygen content. The HTFT process can be carried out based on a precipitated iron catalyst with stability and selectivity promoters. Preferably, the system according to the embodiment is of the LTFT type. In this process, a typically cobalt-based catalyst converts the synthesis gas to mainly linear long-chain paraffins and some lighter olefins, a mixture (methane, petroleum gas, naphtha, kerosene and wax). The liquid and solid products can be upgraded to clean-burning diesel fuel by hydrotreating and cracking. Another preferred product is jet fuel, which is composed mostly of naphtha and kerosene upgraded to specifications. Typical grades are Jet A, Jet A-1, and Jet B. The fuel produced is substantially free of sulfur, aromatics, and nitrogen compounds and is excellent as a blend stock for conventional diesel. Supported cobalt catalysts may be the preferred catalyst for FT synthesis. The most important properties of cobalt FT catalysts are activity, selectivity, usually to C5 and heavier products, and resistance to deactivation. Known catalysts are typically based on titania, silica or alumina supports, with various metals and metal oxides shown to be useful as promoters. FT synthesis can be carried out in several types of chemical reactors, the most common being fixed-bed tubular and slurry bubble column types. Other useful reactors include microchannel reactors; flow moving bed reactors; and reactors packed with internals such as monoliths, sponges, or cassettes for syngas flow direction and improved thermal transfer. By varying the catalyst and process conditions, the products can be directed towards alternative product slates, for example product slates containing higher amounts of olefins and / or oxygenates and constituting a portion of the desired product slate.

[0037] The LTFT process involves the polymerization of carbon monoxide with water. 2nH2+ nCO → -(CH2) n - + nH2O The overall reaction produces linear alkanes. (2n+1)H2+ nCO → C n H (2n+2) + nH2O ΔH ~154KJ / mol(α=0.95) where n is the length of the carbon skeleton. The most important side reaction is the formation of α-alkenes, which is 2nH2+ nCO → C n H 2n + nH2O An alternative route to methane is: 3H2+ CO → CH4+ H2O ΔH=-88KJ / mol.

[0038] Schematically, the feed molecules CO and H2 can be activated on the surface of the FT metal, followed by hydrogenation of carbon and oxygen, successively adding -CH2- monomer units and termini, resulting in chain growth. Alkanes can be formed by hydrogenation of the growing chain, while β-hydrogen abstraction reactions lead to α-alkenes. Surface -CH x Further hydrogenation of ethylene glycol gives methane. For each carbon unit in the product, one water molecule is formed. It should be understood that the above is only a schematic description of the FT mechanism, and several mechanistic pathways have been proposed in the literature. For example, it is possible for the primary product to be an olefin, and for alkanes to be produced by secondary hydrogenation.

[0039] A wide range of chain lengths can be produced by FT synthesis, as determined by the values ​​of the chain termination probability relative to the chain growth probability. In general, the product slate follows an Anderson-Schultz-Flory (SFA) distribution, as described by the following equation: W n / n=(1-α) 2 α n-1 W n is the mass fraction of chains of a particular chain length n, and α is the mass fraction of chains of a particular chain length n, and α=rp / (r p +r t ) we define the chain growth rate according to

[0040] where r p and r t are the propagation and termination reaction rates, respectively. To minimize the production of light gases, it may be preferable to have as high an α as possible, as defined by the actual catalyst and process conditions used.

[0041] The H2 / CO utilization ratio in the LTFT synthesis is 2.05-2.2 depending on α and to some extent on the selectivity to other products besides alkanes. Another important feature of the FT reaction is its highly exothermic nature as mentioned above. The actual enthalpy of the reaction varies with the polymerization probability, olefin to paraffin ratio, deviation from ASF distribution, methane selectivity, and by-product formation. Handling the heat greatly influences the reactor and process design. For fixed bed and slurry reactors, it is convenient to remove heat and control the reaction temperature by boiling water. Analysis of the FT reaction can yield a favorable range of process conditions for the LTFT synthesis, including one or more of the following: Operating temperature 210 °C to 260 °C. At the high end, there may be undesirable production of light gases, including methane. In addition, accelerated deactivation should be considered. On the other hand, the reaction rate is fast and the steam generated by the reaction heat can be obtained at favorable pressures. Too low a temperature may be prohibited by low reaction rate; Increased reaction pressure. Process intensification dictates a reaction pressure of at least 10 bar, most XTL processes operate in the range of 25-30 bar, but even higher pressures may be used. High pressure favors high conversion and the formation of long-chain hydrocarbons; The effective H2 / CO ratio in the feed to the FT reactor is close to or slightly lower than 2. Since this is lower than the consumption rate, the H2 / CO ratio decreases further along the reaction path that favors the synthesis of long hydrocarbon chains.

[0042] The embodiment includes the use of synthesis gas for the Fischer-Tropsch reaction. The synthesis gas can be washed and pre-treated in an appropriate manner so that the gas fed to the FT reactor 3 contains substantially CO and hydrogen. Such washing can include sulfur removal, for example in a ZnO absorbent. Activated carbon and / or zeolites can be used to remove ammonia and other trace impurities such as metal carbonyls. Synthesis gas can be produced by mixing hydrogen with CO2 and shifting the CO2 to CO in a CO production system 1 including an rWGS reactor. By recycling unconverted synthesis gas and possibly using a pre-reformer, the feed to the CO production system can include hydrogen, CO, CO2, water steam and some methane. There is an equilibrium relationship between these components given by the following stoichiometric equation: CO + H2O = CO2 + H2.

[0043] This reaction is called the water-gas shift reaction, and by operating the shift reactor at certain conditions, the equilibrium can be forced to the left, thereby resulting in a reverse water gas shift (RWGS). A gas mixture can be obtained that is rich in carbon monoxide and has a reduced concentration of carbon dioxide. The shift of the reaction towards CO is favored by high temperature and high partial pressure of hydrogen. Excess hydrogen in the process may be required in either case, since hydrogen is an important component in the final synthesis gas. By using a suitable catalyst, the reaction rate can be improved. However, it is understood that at high temperatures above 800°C, preferably above 1000°C, no catalyst is required. The shift process is nearly pressure independent and the same pressures as the other process units can be used. In a traditional "high temperature" shift reactor, the typical outlet temperature is 420°C. It should be noted that "high temperature" here refers to a different temperature range than the FT reactor, and much higher temperatures can be applied for the reverse water gas shift reaction. Catalysts for traditional "high temperature" shift reactors can be based on chromium and / or iron.

[0044] From the water gas shift equation above, it can be seen that water in the feed is not beneficial to the RWGS reaction according to Le Chatelier's principle. However, if RWGS is carried out above 500-600 °C, some steam and / or CO2 is expected to be required to suppress coking in the feed lines. Methane may also be present in the feed to the RWGS reactor, for example, less than 10 mol %. Methane is inert to the FT reaction. Some methane may be produced by the FT reaction. If this methane is not removed by a purge stream, it may accumulate in the system for recycle. The purge stream removes carbon from the system, thereby potentially reducing the overall product yield. Note that some purging may be required, for example, if residual nitrogen and other inert gases are removed. A preferred option is to convert the methane within the RWGS reactor itself. One option is for this reactor to be a combination of RWGS and a steam methane reformer (SMR). SMR typically uses a catalyst based on nickel as the active metal on a high temperature support material such as a spinel compound or alumina. The SMR catalyst may also act synergistically to increase the reaction rate and ensure equilibrium in the RWGS reactions. The following chemical reactions are carried out by the steam reforming of methane, in addition to the shift reaction: CH4 + H2O = CO + 3H2 Thus, more synthesis gas can be produced, ready to be converted to products. The heat of reaction for steam reforming is strongly endothermic, in addition to the endothermic nature of the RWGS reaction. However, the amount of methane can be limited. In either case, a significant temperature drop can occur if no additional heat is provided. It may be necessary to heat the gas stream to the RWGS. The additional heat may be provided by suitable means, for example electrical resistance or induction heating. Internal or external combustion is also a possibility. In the latter case, oxygen produced by electrolysis of water can be used.

[0045] The RWGS-SMR reactor described above is very different from conventional SMR reactors. In conventional SMR reactors, methane is converted at high temperature and moderate pressure in a tubular reactor. A world-scale steam reformer consists of many reactor tubes, for example 200-250 tubes, typically with a length of 12-13 meters, an inner diameter of about 10 cm, and an outer diameter of about 12 cm. This requires a space of 30-50 m in length, 10-12 m in width, and 15-20 m in height for a unit. Conventional steam reformers are operated in the pressure range of 15-30 bar. The outlet temperature of the gas from a conventional steam reformer is in the temperature region of 950 °C. The energy used to carry out the endothermic reaction is supplied by external firing / heating (top, side, bottom, or terrace firing). The ratio between steam and carbon is for example 2.5-3.5, and the ratio between hydrogen and carbon monoxide in the product stream is for example 2.7-3.0.

[0046] Alternatively, natural gas reforming can be carried out in an autothermal reformer (ATR). In an ATR, methane is fed to a combustion chamber (burner) along with oxygen, enriched air or air. The energy required to operate the endothermic steam reforming reaction is provided by the exothermic reaction between methane and / or hydrogen and oxygen according to the following equation: CH4+(1 / 2)O2→ CO + 2H2.

[0047] Temperatures in the combustion chamber can reach over 1500 °C, or even over 2000 °C. After the combustion chamber, the reaction is driven to equilibrium on a catalyst bed before the synthesis gas leaves the reactor at about 1000-1050 °C. The size of such units is, for example, 10-15 meters high and 5-6 meters in diameter. Typical ratios of steam:carbon are 0.6-1.4. Steam is often partially mixed with oxygen, at least when pure oxygen is used. Pure oxygen is very reactive, and mixing with steam makes it easier to handle.

[0048] Catalysts used in ATRs most often contain nickel on a high temperature stable support material. In some cases, palladium is used, for example, in the upper part of the catalyst bed. High temperature inert materials are often used in the upper part of the catalyst bed to protect the catalyst from exposure to hot gases from the burner, and in the lower part to fix the support for the catalyst. The inert material is composed of high temperature stable materials that may include one or more of alumina, magnesia, magnesium oxide, silica, zirconia, and titania. Specifically, the inert material may be alpha-alumina, a spinel compound, or cordierite. The latter, 2MgO2Al2O35Si2, is often used as a support material for exhaust catalysts in the form of a monolith. Other suitable shapes of inert materials or catalyst supports are the formation of spheres, extrudates, tubes, and wagon wheels. The tubes are sometimes called Raschig rings.

[0049] A further option for reforming natural gas is the partial oxidation reactor (POX), which is also an autothermal reformer, except that the unit does not contain a catalyst bed. Traditionally, the exit gas is rapidly cooled using a waste heat boiler (WHB) that generates steam. Rapid cooling and the use of tubes containing boiling water are important to inhibit material corrosion due to metal dusting. POX usually operates at high temperatures, above 1200 °C. This has the advantage that methane and other hydrocarbons are instantly partially combusted to synthesis gas, avoiding any potential coking. The disadvantage is reduced energy efficiency. Developments are being made to design lower temperature POX technologies, for example below 800 °C.

[0050] From the above discussion of RWGS, SMR, ATR, and POX, it can be seen that there are many options for producing synthesis gas from natural gas and for converting tail gas in the recycle stream. The CO production system 1 may be a combined RWGS-POX reactor or may be two separate sections. Hydrogen may be added directly to the RWGS-POX reactor and / or to the RWGS section.

[0051] Optional pre-treatment of the recycle gas to the RWGS reactor can include pre-reforming, where higher hydrocarbons such as ethane are converted to methane and CO2 by means of steam. Pre-reforming can be carried out at pressures within the interval of 5-200 bar, preferably 10-30 bar. Pre-reforming can be carried out at temperatures between 300 and 700°C. The reaction in the pre-reformer is for example: C3H8+ 2H2O → CO2+ 2CH4+ H2 and CH3OH + H2O → CO2+ 3H2.

[0052] Both propane and methanol, as examples of hydrocarbons and oxygenates, can be converted to gaseous molecules already present in the feed stream to the process, in addition to methane. The main advantage of having a pre-reformer can be that molecules prone to coking are removed from the system. It is also possible to purposefully remove and recycle additional light components from the liquid hydrocarbon product to the pre-reformer by flashing at a desired temperature.

[0053] Certain embodiments of the RWGS reactor have been described above. However, there are possible drawbacks when this reactor, or the RWGS-SMR combined reactor, or the RWGS-POX reactor, contains a catalyst, such as a nickel-containing catalyst. This is because nickel is prone to coking under certain process conditions and in certain feed compositions. Surprisingly, the use of a pre-reformer is not necessary and an alternative method has been found to inhibit coking. Although the reactor used is called a synthesis gas reactor, the predominant reaction is still the RWGS reaction. Reactions that are inhibited include: CO2 → CO + C Boudouard reaction C n H n+2 → C n + nH2 caulking CH4 → C + 2H2 Methane decomposition CO + H2 → C + H2O CO reduction.

[0054] The last reaction is the reformation of the Boudouard reaction combined with the RWGS reaction. The CO reduction is suppressed by having steam in the feed to the reactor. Such steam can be added to any of the feeds, i.e. for the recycle gas, oxygen or CO2, as long as it does not exceed the critical value for the reaction to proceed. In particular, it is advantageous to add steam to the recycle gas containing CO. One possibility is to use the steam generated by cooling the FT reactor. Another possibility is to add oxygen and possibly hydrogen so that sufficient steam is generated. If a pre-reformer is used, water steam is added before this treatment unit, as mentioned above.

[0055] However, embodiments use a carbon source that contains both CO and CO, and it has been found that such a carbon source can eliminate the need for a dedicated RWGS reactor, or portion of a reactor, particularly the RWGS reactor that processes the carbon-containing gas stream 32, which is the primary carbon input to the fuel production system.

[0056] FIG. 2 includes a table showing the composition (mol %) of the carbon source according to the comparative examples and embodiments described below.

[0057] Comparative Example 1 Comparative Example 1 represents a range of carbon sources based on natural gas reforming. Clearly, the CO2 / CO ratios shown in Figure 2 are outside the scope of the technology of the embodiment. Furthermore, the nitrogen content is relatively low.

[0058] Comparative Example 2 Comparative Example 2 represents a pure or near-pure carbon source consisting essentially of CO2. This could be CO2 extracted from the atmosphere, hydrocarbons completely combusted with the water formed, or gases from gasification where CO2 has been separated. Clearly, such high CO2 concentrations are not compatible with the technology of the embodiments.

[0059] Examples 1 to 6 Examples 1-6 are all according to embodiments of the present invention and have the carbon source composition as shown in the table shown in FIG. 2. These examples 1-6 correspond to cases 1-6, respectively, where the carbon source comes from electrochemical carbothermal reduction to produce ferromanganese. All data are based on simulations of the process shown in FIG. 1, assuming the following conditions: FT reactor temperature = 210°C; pressure = 30 bar; H2 / CO feed ratio = 2.0-2.2; CO conversion = 90%; methane selectivity 8.84 mol%. 75% of the produced hydrogen is sent directly to the FT reactor 3, the rest to the CO generation system 1. FIG. 3 shows the mole fractions and CO2 / CO ratios in the feed to the FT reactor 3. The feed to the Fischer-Tropsch reactor 3 is shown to contain at least 9 mol% nitrogen, a total of 15 mol% inerts (CO2+N2), and a CO2 / CO ratio less than 0.5 but greater than 0.2.

[0060] It should be noted that the RWGS-POX reactor is used as the CO production system 1 to essentially remove all methane and gaseous hydrocarbons from the recycled tail gas and partially convert CO2 to CO. The temperatures outside the POX cross section, i.e., the first cross section, of the reactor are 1341°C, 1466°C, and 1391°C for cases 1, 5, and 6, respectively. The temperatures outside the RWGS cross section, i.e., the second cross section, of the reactor are 1118°C, 1127°C, and 1165°C for cases 1, 5, and 6, respectively. Figure 4 shows the mole fractions in the dry tail gas, excluding ethane and higher hydrocarbons, which are less than 1 mol%. This figure shows that the recycled gas, i.e., part of the tail gas, has a CO2 / CO ratio substantially higher than 1.0 and even higher than 2, and therefore, as implemented in the CO production system 1, some CO2 must be converted to CO. The total amount of inerts in the FT reaction is at least 65 mol% (N2+CH4+CO2), with nitrogen alone being at least 35 mol%.

[0061] Example 7 A schematic block diagram of example embodiment 7 is shown in Figure 5, in which fluid streams 11, 12, 13, 21, 31, 32, 33, 41, 42, 43, 44 and 45, and process units 1, 2, 3 and 4 are all shown as previously described with reference to Figure 1. Example 7 differs from the previously described embodiments by further including a conduit for supporting fluid stream 14.

[0062] Fluid stream 14 may add other organic sources to the CO2 generating system 1. Such other organic sources may be biomass or pretreated biomass. Biomass may be any type of waste, e.g., forestry waste or crop residues; or biomass grown for a purpose. Pretreated biomass includes torrefaction, pyrolysis, as well as gasification and fermentation. Other organic sources are, at least in part, municipal waste; and fossil coal, oil and / or gas. These other organic sources may also be pretreated in some way, such as off-gas from industrial plants, refineries, etc. An added product in fluid stream 14 may be CO2 from any source. In this embodiment, a carbon source for generating fuel is included in both streams 32 and 14.

[0063] Figure 6 is another schematic block diagram of at least some of the components of a fuel production system according to one embodiment. In Figure 6, fluid streams 11, 12, 13, 14, 31, 32, 33, 41, 42, 43 and 44 are all as previously described with reference to Figures 1 and 5. In Figure 6, process units 1, 3 and 4 are all as previously described with reference to Figures 1 and 5. The embodiment of Figure 6 may further include a scrubbing section 2, as previously described with reference to Figures 1 and 5, although this is not shown in Figure 6.

[0064] Example 8 Figure 6 illustrates some of the additional devices and systems for generating electricity from the feed that is the input to the fuel power generation system described above, according to embodiments. Figure 6 also illustrates some of the additional devices and systems for supporting the output flow of fluid from the fuel power generation system described above, according to embodiments.

[0065] System component 605 may be an Fe / Mn / Si reduction furnace. Input 614 to system component 605 may be electrical power. Input 615 to system component 605 may be biocarbon. Gas stream 616 may be the primary carbon source for the furnace gas and fuel production system. System component 606 may be configured to cool, compress, and / or buffer the furnace gas in gas stream 616.

[0066] System component 609 may be another carbon source such as biogas or CO2.

[0067] System input 610 may be electrical power, which may be rectified in system component 601 and then input to system component 603. System input 611 may be water. System component 602 may be a water purification system. Fluid stream 612 may be a substantially pure water stream input to system component 603. System component 603 may be a system configured to perform alkaline electrolysis of water received in stream 612. Fluid stream 12 may be hydrogen produced by electrolysis performed in system component 603. Fluid stream 11 may be oxygen produced by electrolysis performed in system component 603. Fluid stream 613 may be a substantially pure water stream input to cooling of FT reactor 3.

[0068] Fluid stream 617 may be a vapor stream exiting the cooling system of the FT reactor 3 .

[0069] Fluid stream 618 may be a water stream exiting the CO2 production system 1 and / or scrubbing section 2 (not shown in FIG. 6). System component 604 may be configured to scrub water received via inputs 618 and 41. Fluid stream 619 may be a clean water stream exiting the fuel production system.

[0070] Fluid stream 42a may be a flow of medium Fischer-Tropsch liquid (MFTL) and the primary output of the fuel production system. System components 607 may be configured to store, meter, and / or process the flow of medium Fischer-Tropsch liquid.

[0071] Fluid stream 42b may be a stream of heavy Fischer-Tropsch liquids (HFTL) and the primary output of the fuel production system. System components 608 may be configured to store, meter, and / or process the stream of heavy Fischer-Tropsch liquids.

[0072] The CO generation system 1, which may include a POX (partial oxidation) reactor, may be a syngas generation system. The CO generation system 1 may include a POX burner, a POX reactor, a syngas cooler and heat recovery, and a syngas cleaning system.

[0073] The purge gas in stream 43 can be combusted in a fired heater. The fired heater can be part of a syngas production system in the CO production system 1. The fired heater can provide heat to the CO production system 1.

[0074] Systems according to embodiments can use renewable electricity in the production of liquid hydrocarbons, MFTL and HFTL, which can directly replace fuels based on fossil oil and gas. These new fuels are called electric fuels or e-fuels and can be, for example, SAF (sustainable aviation fuel).

[0075] The embodiments improve upon the known art by: -Use a carbon source in gaseous form that contains large amounts of both CO and CO2; The received CO2 / CO mixture has been doped with hydrogen and can then be fed directly to the FT reactor 3; -CO2 is sent to a CO generation system 1 together with methane gas and other hydrocarbon gases, as well as some unreacted hydrogen and CO. The CO generation system 1 may be conventional and may be commercially available; - The CO generation system 1 is capable of converting the hydrocarbon gases produced in the FT reactor 3, and most of the CO2 (e.g., via the FT reactor 3) from a carbon source into synthesis gas. This is achieved by the following functions / characteristics: Partial oxidation of hydrocarbon gases using oxygen from water electrolysis o rWGS of CO2 using unreacted hydrogen from the FT reactor 3 and some hydrogen from electrolysis, where the amount of hydrogen added is low enough to keep operating conditions within known operating ranges in industrial scale operation of the CO generation system 1 while meeting the criteria required to achieve rWGS conversion of CO2; Virtually no / negligible soot / coke formation and virtually no issues with metal dusting; Virtually no pre-reforming of the hydrocarbon gases from the FT reactor is required (to avoid soot / coke formation and avoid metal dusting challenges) o Virtually no additional steam injection is required (to avoid soot / coke formation and avoid metal dusting challenges); o Virtually no catalyst is required due to the high temperature gas outlet temperature (>1400°C) from the POX section of the CO generation system 1; High conversion rate of CO2 due to high temperature - Shortening of holding time due to high temperature o The high temperatures are achieved by partial oxidation of the hydrocarbon gas. If the amount of hydrocarbon gas from the FT reactor 3 is too low to reach the high temperatures, additional combustible material can be used. This could be an additional carbon source, such as biogas, shown by input stream 14 in Figures 5 and 6.

[0076] A fuel production system according to embodiments can utilize several different carbon sources within the same plant, for example, but not limited to: - Blast furnace gas from ferromanganese plants - Blast furnace gas from ferrosilicon plants -CO2 obtained from the atmosphere and industrial sources.

[0077] Such gases also typically contain significant and rapidly varying amounts of nitrogen (N2). The ratio between CO2 and CO can also change substantially and rapidly (e.g., within a few minutes). High inert gas content and large and rapid changes in gas composition (CO / CO2 and N2) are challenges for known systems. However, the CO generation system 1 and FT reactor 3 according to the embodiment can operate advantageously despite substantial and rapid changes in CO, CO2 and N2.

[0078] The embodiments include many modifications and variations on the techniques described above.

[0079] In particular, the CO2 generation system 1 may be a reactor 1 as disclosed in WO2021 / 185869A1, the entire contents of which are incorporated herein by reference. The CO2 generation system 1 may be a reactor system comprising multiple reactors. One or more of the reactors may be a reactor 1 as disclosed in WO2021 / 185869A1.

[0080] The CO production system 1 can include either a catalytic or non-catalytic partial oxidation reformer.

[0081] Embodiments include using one or more heat exchangers, compressors, pumps, coolers, heaters, cleaning sections, water removal sections, and / or other components in the fuel production system that can be in addition to the components shown in Figures 1, 5, and 6.

[0082] Embodiments include the following numbered clauses: 1. A process for producing hydrocarbons using the Fischer-Tropsch process, comprising: - Use a carbon source that contains a molar CO2 / CO ratio of at least 0.10 -A carbon source containing a molar CO2 / CO ratio of less than 2.0 - a carbon source containing at least 3 mol% H - Fischer-Tropsch process using supported cobalt catalyst - Fischer-Tropsch tail gas containing a molar CO2 / CO ratio of at least 1.0 - At least 30% of the Fischer-Tropsch tail gas is recycled to the reformer.

[0083] 2. The method according to clause 1, wherein off-gas from the production of iron or ferroalloys is used as the carbon source.

[0084] 3. The method according to clause 2, wherein off-gas from the production of ferromanganese is used as the carbon source.

[0085] 4. The method according to clause 1, wherein gas from reformed natural gas is used as the carbon source.

[0086] 5. The method according to clause 4, wherein the reforming is carried out at a temperature below 800°C, preferably below 700°C, more preferably below 600°C.

[0087] 6. The method according to claim 4, wherein a catalytic partial oxidation is used as the reformer.

[0088] 7. The method of claim 6, wherein the catalyst comprises at least one precious metal.

[0089] 8. The method according to clause 1, wherein gas from the gasification of biomass is used as the carbon source.

[0090] 9. The method according to any of the above clauses, wherein hydrogen is added to the process from the electrolysis of water.

[0091] 10. The method of claim 1, wherein the reformer is a non-catalytic POX (partial oxidation) reactor.

[0092] 11. The method of claim 1, wherein the carbon source contains at least 1.0 mol %, preferably at least 3 mol %, more preferably at least 10 mol % N2.

[0093] 12. The method of claim 11, wherein the feed to the Fischer-Tropsch reactor contains at least 3 mol %, preferably at least 8 mol %, more preferably at least 12 mol % nitrogen.

[0094] 13. The method according to any of the above clauses, wherein at least 80%, preferably more than 85%, more preferably more than 90% of the carbon in the carbon source is converted to liquid hydrocarbons.

[0095] 14. The method according to any of the preceding clauses, wherein the carbon source contains a molar CO2 / CO ratio of at least 0.15, preferably at least 0.20, more preferably at least 0.25.

[0096] 15. The method according to any of the above clauses, wherein the carbon source contains a molar CO2 / CO ratio of less than 1.5, preferably less than 1.0, more preferably less than 0.5.

[0097] 16. The method according to any of the preceding clauses, wherein the tail gas contains a molar CO2 / CO ratio of at least 1.5, preferably at least 2.0, more preferably at least 2.5.

[0098] 17. The method according to any of the above clauses, wherein the POX reactor is fed, in addition to a portion of the tail gas, by an alternative carbon source, such as biomass or pretreated biomass; off-gas from an industrial plant; municipal waste; or any other hydrocarbon source.

[0099] The flow charts and their descriptions herein should not be understood as prescribing a fixed order of performing the method steps described therein. Rather, the method steps may be performed in any order possible. Although the present invention has been described in connection with certain exemplary embodiments, it should be understood that various changes, substitutions, and alterations apparent to those skilled in the art can be made to the disclosed embodiments without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. 1. A fuel production system comprising: Fischer-Tropsch (FT) reactor systems; Carbon source and H ２ to the FT reactor system; Equipped with The carbon source is at least 0.10 molar CO ２ CO and CO ２ Includes both CO and H to the FT reactor system ２ The supply of is a supply of synthesis gas, The FT reactor system is configured to produce a fuel in response to the received synthesis gas. Fuel generation system.

2. The fuel production system of claim 1 , wherein the carbon source is an output gas from a metal reduction furnace.

3. the fuel production system further comprises a separation system configured to receive output products from the FT reactor and separate them into at least one or more liquid fuels and a tail gas; The tail gas is a mixture of synthesis gas, CO ２ and gaseous hydrocarbons, The fuel production system of claim 1 .

4. The fuel production system further comprises: CO generation system; O2 to the CO2 generating system 2 supply pipes supplying the H for the CO generating system ２ a supply pipe for supplying the a supply line configured to supply at least a portion of the tail gas to the CO production system; an output pipe configured to supply an output product from the CO production system to the FT reactor system; Equipped with the output products from the CO2 production system include synthesis gas produced in dependence on at least the received tail gas; The fuel production system of claim 3 .

5. the fuel production system further comprises a scrubbing section 2 disposed in a fluid flow path between the CO production system and the FT reactor system; the scrubbing section is configured to remove water from the output product from the CO2 production system.

5. The fuel production system of claim 4.

6. 5. The fuel production system of claim 4, further comprising a supply line configured to supply at least a portion of the tail gas to the FT reactor system in a gas recirculation loop that does not pass through the CO production system.

7. The fuel production system of claim 4 , further comprising supplying an additional carbon source to the CO production system.

8. The carbon source is CO ２ 8. The fuel generation system of claim 7, comprising one or more of: biomass, municipal waste, fossil coal, oil, or gas.

9. The fuel production system further comprises: an output tube that outputs a portion of the tail gas as a purge gas; a burner configured to receive and combust at least a portion of the purge gas, thereby generating heat for use in the fuel production system; Equipped with The fuel production system of claim 2 .

10. The fuel production system of claim 4 , wherein the CO production system comprises a partial oxidation (POX) reactor and / or a reformer.

11. At least 0.10 mol CO ２ The carbon source has a molar CO / CO ratio of about 0.15 or greater, preferably 0.20 or greater, and more preferably 0.25 or greater. ２ 10. The fuel production system of claim 1, having a CO / CO ratio.

12. The carbon source, which is the exhaust gas from a metal reduction furnace, has a molar CO content of about 2.0 or less, preferably about 1.5 or less, more preferably 1.0 or less, more preferably about 0.5 or less. ２ 10. The fuel production system of claim 1, having a CO / CO ratio.

13. The fuel production system of claim 4 , wherein at least 30% of the tail gas is supplied to the CO production system.

14. Molar CO that is at least 0.10 ２ the carbon source having a CO / CO ratio is produced by reforming natural gas; The modification is carried out at a temperature of less than 800°C, preferably less than 700°C, more preferably less than 600°C; The fuel production system of claim 1 .

15. 5. The fuel production system of claim 4, wherein the CO production system is configured to operate at temperatures above 1000°C, preferably above 1100°C, more preferably above 1200°C, more preferably above 1400°C.

16. The tail gas contains mol CO ２ 4. The fuel production system of claim 3, wherein the CO / CO ratio is 1.

17. The carbon source provided contains at least 3 mol % H ２ The fuel production system of claim 1 , comprising:

18. The carbon source, which is the exhaust gas from a metal reduction furnace, contains at least 1.0 mol %, preferably at least 3 mol %, and more preferably at least 10 mol % N ２ The fuel production system of claim 1 , comprising:

19. The FT reactor system contains at least 3 mol % N ２ , preferably at least 8 mol % N ２ , more preferably at least 12 mol % N ２ The fuel production system of claim 1 .

20. The tail gas has at least 1.5, preferably at least 2.0, more preferably at least 2.5 mol CO ２ 10. The fuel production system of claim 1, further comprising a CO / CO ratio.

21. 1. A carbon generation and fuel generation system comprising: The fuel production system of claim 1 ; a carbon generator configured to output a carbon source gas and supply the output gas to the fuel generation system; H ２ and O ２ and generating the H ２ and O ２ an electrolysis system configured to supply at least a portion of the A system comprising:

22. 22. The system of claim 21, wherein the carbon generator is a metal reduction furnace, such as an iron production plant, a ferroalloy production ferromanganese production plant, and / or a ferrosilicon production plant.

23. 1. A method for producing a fuel, comprising: generating a carbonaceous gas with a carbon generator; supplying the carbonaceous gas to the fuel power generation system of claim 1; generating electricity from fuel in response to receiving the carbonaceous gas using the fuel generation system; A method having the following.

24. 24. The method of claim 23, wherein the carbon generator is a metal reduction furnace such as an iron production plant, a ferroalloy production ferromanganese production plant, and / or a ferrosilicon production plant.

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