System and process for producing syngas for low carbon methanol production

Abstract

An autothermal reformer (ATR) system and process for producing a methanol synthesis feed form a hydrocarbon feed. The ATR system generally includes: a hydrocarbon feed preheating section; a carbon dioxide recovery unit for capturing carbon dioxide in a flue and producing a carbon dioxide-rich stream; an autothermal reformer unit for producing a syngas product; an electrolysis unit powered by renewable energy 5 or electricity for producing a hydrogen product; and a mixing unit for combining the carbon dioxide-rich stream, the syngas product and the hydrogen product to produce the methanol synthesis feed. The methanol synthesis feed may be supplied to a methanol synthesis section to produce a low carbon methanol product.

Description

SYSTEM AND PROCESS FOR PRODUCING SYNGAS FORLOW CARBON METHANOL PRODUCTIONTECHNICAL FIELD

[0001] The present disclosure relates to autothermal reforming systems and processes for producing syngas from a hydrocarbon feed. The autothermal reforming systems incorporate carbon capture and electrolysis powered by renewable energy or electricity to produce a syngas product for use in low carbon methanol production, such as in a refinery setting.BACKGROUND

[0002] Commercial methanol plants manufacture methanol in several steps which generally include a syngas preparation (reforming) step, a methanol synthesis step and a methanol purification step. Since these steps are conducted in separate process sections, the technology for each section can be selected and optimized independently. The usual criteria for the selection of the technology are capital cost and plant efficiency. The preparation of syngas typically accounts for a majority of the total investment, and almost all energy is consumed in this process section. Therefore, the technology used in producing syngas is of major importance.

[0003] There are two basic types of reforming technologies currently used: steam methane reforming (SMR) and autothermal reforming (ATR). SMR is the most common reforming technology and uses air-fired combustion to generate the heat needed to preheat the hydrocarbon feed and to drive the reforming reaction in the steam methane reformer. During a conventional SMR process the following two reactions take place:CH4 + 2 H2 — ►CO2 + 4 H2CH4 + H2O — ►CO + 3 H2.A water-gas shift reaction can be subsequently performed using steam to convert carbon monoxide to carbon dioxide and generate additional hydrogen. This is typically followed by a pressure swing adsorption step to purify the hydrogen.

[0004] In ATR, the following two exothermic reactions take place:CH4 + O2— ► CO2+ 2 H2CH4+ A CE — ► CO + 2 H2.ATR can achieve relatively high carbon capture compared to conventional steam / hydrocarbon reforming since a majority of the carbon dioxide produced in the oxygen-fired reformer can be recovered from the high- pressure syngas stream using conventional acid gas removal operations. However, air-fired combustion is required in a conventional ATR process to preheat the hydrocarbon feed which, like in SMR, generates a flue gas containing carbon dioxide. In addition, the syngas produced in the ATR process has a module (M=(H2-CC>2) / (CO+CO2)) of 1.8 which is less than the desired module of 2 for methanol synthesis. As a result, a fraction of the syngas is purged to a pressure swing adsorption unit to produce a hydrogen-richstream which is recombined with the syngas and a carbon dioxide-containing offgas stream which is recycled back to the fired preheater with the carbon dioxide eventually ending up in the flue gas. In regions where there is no availability of sequestration capacity, the flue gas (and carbon dioxide) is emitted to the atmosphere.

[0005] In recent years increasing attention has been paid to the impact of carbon dioxide emissions from industrial reforming processes. Accordingly, there is a need within the industry for an efficient and cost- effective decarbonized ATR system and process for producing syngas for low carbon methanol production.SUMMARY

[0006] The present disclosure relates to an autothermal reforming (ATR) system and process for producing syngas from a hydrocarbon feed that uses hydrogen produced in an electrolysis unit powered by renewable energy or electricity and carbon capture to reduce the overall carbon footprint of the ATR system and process. The current disclosure is based on a realization that a pressure swing adsorption unit is not necessary for obtaining the desired module; hydrogen required for addition to the syngas produced by an autothermal reformer unit that would conventionally be provided by the pressure swing adsorption unit can instead be provided by an electrolysis unit powered by renewable energy or electricity. In addition, carbon dioxide in the flue gas that is conventionally emitted from the fired heater can be captured and added back to the syngas product prior to methanol synthesis.

[0007] According to an embodiment, the present disclosure relates to an ATR system for the production of a methanol synthesis feed from a hydrocarbon feed. The ATR system includes: a hydrocarbon feed preheating section arranged to receive the hydrocarbon feed and apply thermal energy to the hydrocarbon feed to produce a preheated hydrocarbon feed and a flue gas; a carbon dioxide recovery unit operable to receive the flue gas and separate carbon dioxide from the flue gas to produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; an autothermal reformer unit arranged to receive the preheated hydrocarbon feed and oxygen and produce a syngas product; an electrolysis unit powered by renewable energy or electricity and operable to receive water and produce an oxygen product and a hydrogen product; and a mixing unit operable to receive and mix the syngas product, the carbon dioxiderich stream and the hydrogen product and produce a methanol synthesis feed. In some embodiments, the electrolysis unit is arranged to supply the oxygen product to the autothermal reformer unit.

[0008] In another embodiment, the present disclosure relates to a process for producing a methanol synthesis feed from a hydrocarbon feed using the ATR system described above. The process includes: supplying the hydrocarbon feed to the hydrocarbon feed preheating section to produce a preheated hydrocarbon feed and flue gas; supplying the flue gas to a carbon dioxide recovery unit to separate carbon dioxide from the flue gas and produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; supplying the preheated hydrocarbon feed and oxygen to an autothermal reformer unit to produce a syngas product; supplying the syngas product, the carbon dioxide rich stream and ahydrogen product produced by an electrolysis unit powered by renewable energy or electricity to a mixing unit to produce the methanol synthesis feed.

[0009] In still another embodiment, the present disclosure relates to a methanol synthesis plant. The methanol synthesis plant includes a hydrocarbon feed preheating section arranged to receive a hydrocarbon feed and apply thermal energy to the hydrocarbon feed to produce a preheated hydrocarbon feed and a flue gas; a carbon dioxide recovery unit arranged to receive the flue gas and separate carbon dioxide from the flue gas to produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; an autothermal reformer unit arranged to receive the preheated hydrocarbon feed and oxygen and produce a syngas product; an electrolysis unit powered by renewable energy or electricity arranged to receive water and produce an oxygen product and a hydrogen product; a mixing unit arranged to receive and mix the syngas product, the carbon dioxide-rich stream and the hydrogen product to produce a methanol synthesis feed stream; and a methanol synthesis section comprising one or more methanol synthesis reactors arranged to receive the methanol synthesis feed stream and produce a methanol product stream comprising low carbon methanol.

[0010] In yet another embodiment, the present disclosure relates to a process for producing low carbon methanol. The process generally includes supplying the methanol synthesis feed produced according to the process described above to a methanol synthesis section comprising one or more methanol synthesis reactors and converting the methanol synthesis feed to a methanol product stream comprising low carbon methanol.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0012] FIG. 1 schematically illustrates an exemplary autothermal reforming system according to embodiments of this disclosure.

[0013] FIG. 2 schematically illustrates an exemplary methanol synthesis plant according to embodiments of this disclosure.DETAILED DESCRIPTION

[0014] It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed compositions, methods, and / or products may be implemented using any number of techniques, whether currently known or not yet in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated hereinbelow, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0015] While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs.

[0016] As utilized herein, “renewable energy” includes energy derived from a sustainable energy source that is replaced rapidly by a natural, ongoing process, and nuclear energy. Accordingly, the term renewable energy refers to energy derived from a non-fossil fuel-based energy source (e.g., energy not produced via the combustion of a fossil fuel such as coal or natural gas). In comparison, “non-renewable energy” is energy derived from a fossil fuel-based energy source (e.g., energy produced via the combustion of a fossil fuel). Fossil fuels are natural fuels, such as coal or gas, formed in the geological past from the remains of living organisms. Accordingly, as utilized herein, renewable energy includes, without limitation, wind, solar power, water flow / movement, or biomass, that is not depleted when used, as opposed to non-renewable energy from a source, such as fossil fuels, that is depleted when used. Renewable energy thus excludes fossil fuel-based energy and includes biofuels.

[0017] As utilized herein, “non-carbon based energy” is energy from a non-carbon based energy source (e.g., energy not produced via the combustion of a carbon-based fuel such as a hydrocarbon).

[0018] As utilized herein, the term “flue gas” refers to the products of combustion, including but not limited to, carbon, carbon dioxide, carbon monoxide, water, hydrogen, nitrogen, sulfur dioxide, chlorine, NO, and / or NO2.

[0019] As utilized herein, electricity may include one or more of “renewable electricity” which refers to electricity produced from a renewable energy source (e.g., wind, solar, geothermal, hydroelectric, nuclear, tide, wave, ocean thermal gradient power, pressure-retarded osmosis, or a combination thereof), “non-carbon based electricity” which refers to electricity produced from a non-carbon based energy source (e.g., hydrogen) and “carbon-based electricity” which refers to electricity produced from a carbon-based energy source (e.g., combustion of hydrocarbons, coal, or hydrogen derived from hydrocarbons).

[0020] As utilized herein, “externally’ combusting” a fuel refers to combusting a fuel outside of a reactor, e.g., in a fired preheater. Combustion as a part of the primary reaction (e.g., combustion which takes place with reforming in ATR) would not be considered externally combusting.

[0021] The term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.

[0022] The term “offgas” refers to a stream that contains a higher concentration of a carbon oxide (i.e., CO2 and / or CO) than is present in ambient air.

[0023] The term “carbon dioxide-rich product” refers to a product stream containing at least 90 vol. % of dioxide or 95 vol. % or more carbon dioxide, for instance 98 vol. % or more carbon dioxide, or 99.5 vol. % or more carbon dioxide.

[0024] The term “low carbon methanol” refers to methanol having a lower carbon footprint as compared to methanol produced conventionally.

[0025] With reference to Figure 1, an ATR system 1 may be considered to include one or more of the following sections or units for converting a hydrocarbon feed (e.g., natural gas) 5 into a methanol synthesis feed 8: a hydrocarbon feed preheating section 10, a carbon dioxide recovery unit 20, an autothermal reformer unit 30, an electrolysis unit 40, and a mixing unit 50. In further embodiments, the ATR system may also include an air separation unit 60. It will be appreciated by those of skill in the art that this is a very simple schematic diagram and that an actual system may include additional sections and units of a standard type capable of heating, chilling, compressing, condensing, pumping, various types of separation and / or fractionation, as well as monitoring of pressures, temperatures, flows, and the like.

[0026] The hydrocarbon feed preheating section 10 can be arranged to receive the hydrocarbon feed 5 and apply thermal energy to the hydrocarbon feed to produce a preheated hydrocarbon feed 15 and flue gas 17. The hydrocarbon feed preheating section 10 may optionally be arranged to also remove undesirable components (e.g., sulfur) from the hydrocarbon feed 5 and / or adjust the pressure of the hydrocarbon feed during conversion of the hydrocarbon feed 5 to a preheated hydrocarbon feed 15. The carbon dioxide recovery unit 20 can be arranged to receive the flue gas 17 and separate carbon dioxide from the flue gas to produce a carbon dioxide-rich product 25 and an offgas 27 containing a substantially reduced amount of carbon dioxide. The autothermal reformer unit 30 can be arranged to receive the preheated hydrocarbon feed 15 and oxygen 21 and carry out syngas generation by the autothermal reforming of the preheated hydrocarbon feed 15 to produce a syngas product 35. The electrolysis unit 40 is powered by renewable energy or electricity and can be arranged to receive water and produce a hydrogen product 45 and an oxygen product 47. In some embodiments, the electrolysis unit 30 is arranged to supply the oxygen product to the autothermal reformer unit 30. A mixing unit 50 can be arranged to receive and mix the syngas product 35, the carbon dioxide-rich product 25 and the hydrogen product 45 to produce the methanol synthesis feed 8. In further embodiments, an air separation unit 60 can be arranged to receive air and produce an oxygen stream 65. In some embodiments, oxygen 21 supplied to the autothermal reformer unit 30 may include the oxygen product 47, the oxygen stream 65 or a mixture thereof.

[0027] As mentioned above, hydrogen input into the syngas product 35 that is conventionally provided via a pressure swing adsorption unit is completely replaced by the hydrogen product 45 produced by anelectrolysis unit 40 that is powered by renewable energy or electricity. In addition, carbon dioxide in the flue gas 17 emitted from the fired preheater is captured and added to the syngas product 35 before its synthesis to methanol. In this way, carbon dioxide may be recycled through the system essentially to extinction except for the offgas. Thus, a benefit derived via the disclosed ATR system and process may be a reduction in the greenhouse gas (GHG) emissions from the system and process. In some embodiments the ATR system and process allow for substantially complete (for e.g., up to 80%) carbon capture.

[0028] As noted above with reference to the embodiment of Figure 1, in embodiments, the ATR system 1 of this disclosure comprises a hydrocarbon feed preheating section 10. Hydrocarbons (e.g., natural gas) are introduced into the ATR system 1 via hydrocarbon feed 5. The hydrocarbon feed 5 is preheated by thermal energy from combustion of fuel in a fired preheater in the hydrocarbon feed preheating section 10 to produce a preheated hydrocarbon feed 15. The hydrocarbon feed preheating section 10 may be configured to provide sufficient thermal energy to the hydrocarbon feed 5 via combustion to convert the hydrocarbon feed 5 to the preheated hydrocarbon feed 15 which may have a temperature of at least 350°C or at least 400°C, or at least 450°C, or at least 500°C, or at least 550°C, or greater than 600°C, or greater than 650°C.

[0029] The hydrocarbon feed preheating section 10 may also be configured to adjust the pressure of the hydrocarbon feed to a desired operating pressure for the downstream autothermal reformer unit 30. Thus, the hydrocarbon feed preheating section 10 may include an apparatus for feed gas pressure adjustment, operable to adjust the pressure of the hydrocarbon feed 5 introduced thereto. One or more compressors may be utilized to increase the pressure of the hydrocarbon feed 5. In other embodiments, if the delivery pressure of the hydrocarbon feed 5 is higher than that required for the process, the pressure is lowered through a powergenerating turbine such that the energy of the excess pressure is recovered, e.g., as electrical energy. For example, an expander may be utilized to convert feed line pressure (e.g., from 500 psig to less than about 50 psig).

[0030] In embodiments where the hydrocarbon feed includes contaminants, it may be desirable to remove contaminants such as sulfur to reduce deactivation of the catalyst(s) used in subsequent steps. Sulfur removal can utilize catalytic hydrogenation to convert sulfur compounds in the hydrocarbon feed 5 to gaseous hydrogen sulfide. The gaseous hydrogen sulfide can then be adsorbed and removed by passing it through beds of, for example, zinc oxide, where it is converted to solid zinc sulfide.

[0031] As noted above with reference to the embodiment of Figure 1, the ATR system 1 also includes a carbon dioxide recovery unit 20. The carbon dioxide recovery unit 20 is configured to receive the flue gas 17 and separate carbon dioxide from the flue gas 17 to produce the carbon dioxide-rich product 25 and offgas 27. The carbon dioxide recovery unit 20 used may in principle be any apparatus and process suitable for the separation and concentration of carbon dioxide from a carbon dioxide-containing gas stream that also includes inert gases, for instance nitrogen and argon, and possibly water as further components. Corresponding apparatuses and processes are known to those skilled in the art. A general overview of possible apparatusesand processes can be found, for example, in Ullmann's Encyclopedia of Industrial Chemistry, “Carbon Dioxide” chapter, Section 13.3 “CCS-related Separation Technologies”, 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. Particular examples include gas scrubbing apparatuses and processes in which the carbon dioxide is physically or chemically absorbed in a gas scrubbing solvent and subsequently desorbed again, and membrane apparatuses and processes in which the carbon dioxide is separated off by means of a carbon dioxide-sensitive membrane.

[0032] In the case of physical absorption, the carbon dioxide is absorbed in an absorber under elevated pressure in a solvent, for instance methanol, N-methylpyrrolidone or polyethylene glycol dimethyl ether, and subsequently desorbed again under expansion in a desorber. The carbon dioxide-depleted solvent is typically recycled back to the absorber.

[0033] In some embodiments, preference is given to chemical absorption in a solvent that chemically binds carbon dioxide. Chemical absorption generally does not require the higher pressures used in physical adsorption. Chemically active solvents that may be used are basic solvents. In chemical absorption, carbon dioxide is absorbed in an absorber in a basic solvent and a carbon dioxide-rich product is released from the carbon dioxide-laden solvent in a desorber. The carbon dioxide-depleted basic solvent is typically recycled back to the absorber.

[0034] The basic solvents are typically aqueous solutions of basic inorganic or organic substances. Basic inorganic substances include, for instance, salts of hydrogen carbonate, and basic organic substances include organic amines. Typically, the water content of the aqueous solutions is 20% to 80% by weight, or about 40% to 60% by weight, or about 45% to 55% by weight.

[0035] In embodiments, the basic solvent is an aqueous solution of an organic amine. The amines may be linear or cyclic, unbranched or branched compounds. Examples include, but are not limited to, monethanolamine, diethanolamine, triethanolamine, diethylethanolamine (DEEA), methyldiethanolamine (MDEA), 3-dimethylamino-I-propanol (DIMAP), dimethylethanolamine (DMEA), methyldiisopropanolamine (MDIPA), l-amino-2-methylpropan-2-ol, diethylenetriamine, bis(3- methylaminopropyl)methylamine, dimethyldipropylenetriamine, dipropylenetriamine, N,N',N"- trimethylbis(hexamethylene)triamine, bis(3-dimethylaminopropyl)amine, piperazine, N- hydroxyethylpiperazine, N-aminoethylpiperazine, 2-methylpiperazine, 2,5 -dimethylpiperazine, triethylenediamine, 1 -hydroxyethylpiperidine, 2-hydroxyethylpiperidine, bis(hydroxyethyl)piperazine, N,N'- dimethylpiperazine, 2,5 -dimethylpiperazine, 2,4,6-trimethyl-[ 1 ,3,5]triazinane, 1 -methyl-2-pyrrolidineethanol, 2-amino-2-methyl-I -propanol, triethylenediamine, N-methyldiethanolamine and tertbutylaminoethoxy ethanol .

[0036] Typically, in chemical absorption, the flue gas is contacted with the basic solvent in an absorber at a temperature of about I0°-I00°C. Absorbers used may be any apparatus suitable for absorptionof carbon dioxide from a flue gas stream. Typically, absorption is accomplished using absorption columns. For better heat and mass transfer, these may include structured packings or trays. On contact with the basic solvent, the carbon dioxide is chemically bound therein. The components not absorbed in the basic solvent are conducted out of the absorption column as offgas. The carbon dioxide-laden solvent is drawn off at the bottom of the absorber, fed to the absorber and stripped with steam therein in order to release the carbon dioxide again. Advantageously, the desorber is operated at a temperature of about 40°-110°C higher than the absorber. Typically, desorption is accomplished using desorption columns. For better heat and mass transfer, these also advantageously include structured packings or trays. Water is first advantageously condensed out of the desorption stream obtained at the top of the desorber. The water condensed out can then, for example, be recycled back into the carbon dioxide recovery process. The solvent that has been depleted of carbon dioxide and water is then recycled to the absorber.

[0037] Both of the absorber and desorber can typically be operated at about 0.1-0.3 MPa; the exact pressures are generally guided by the downstream process steps and can be determined easily by the person skilled in the art. Alternatively, the absorption can also be operated at higher pressures.

[0038] Since the desorption is typically affected at higher temperature than the absorption, the carbon dioxide-laden solvent withdrawn from the absorber should be heated, and the carbon dioxide- and water-depleted solvent withdrawn from the desorber should be cooled for reuse thereof in the absorber. It is therefore particularly advantageous for the energy efficiency of the carbon dioxide recovery to use what is called a crossflow heat exchanger, in which the warmer solvent from the desorber heats up the colder solvent from the absorber. The use of further solvent heat exchangers can further increase the energy efficiency of the process. The exact setting of the temperature of the carbon dioxide-depleted solvent for use thereof in the absorber can then be affected, for example, by means of an air or water cooler.

[0039] Other options for recovering carbon dioxide from the flue gas 17 can include a membrane separation system that contains membranes selective to carbon dioxide over hydrogen, carbon monoxide, and methane. The preferred form is a composite membrane. Modem composite membranes typically comprise a highly permeable, but relatively non-selective, support membrane that provides mechanical strength, coated with a thin selective layer of another material that is primarily responsible for the separation properties. Typically, but not necessarily, such a composite membrane is made by solution-casting the support membrane, then solution-coating the selective layer. Preparation techniques for making composite membranes of this type are well-known. The membranes may be manufactured as flat sheets or as fibers and housed in any convenient module form, including spiral-wound modules, plate-and-frame modules, and potted hollow fiber modules.

[0040] In another embodiment, the carbon dioxide may be separated / recovered from the flue gas 17 by condensation against a cold refrigerant. In a variant, the flue gas 17 may be compressed sufficiently to enable carbon dioxide condensation against cooling water and thus avoiding the need for refrigeration. Recovery ofcarbon dioxide from a gas stream by condensation is known in the art and will therefore be understood by the skilled man. For example, its known to use a distillation column in series with a carbon dioxide specific membrane for carbon dioxide recovery, whereby a part of the carbon dioxide exiting the column overheads is recovered using the membrane and, after being compressed, is recycled to the column feed stream.

[0041] The system used to recover the carbon dioxide-rich product by condensation generally includes a refrigeration unit, which provides the refrigerant against which the carbon dioxide can be condensed. The apparatus may also comprise one or more of the following: a chiller to remove most of the water vapor present; a water collection and removal facility; driers to dry the gas; and one or more heat exchangers.

[0042] The liquid carbon dioxide would usually be produced at pressures of typically 20-40 bar, but this pressure could be readily increased to higher pressures if needed by pumping alone, without the need for expensive additional compression facilities. Lower pressures could be used, but as the pressure is decreased so does the carbon dioxide condensing temperature; the refrigeration energy requirement and cost thus increase and ultimately become prohibitive. In the event that the carbon dioxide is required in gaseous form, once the liquid carbon dioxide has been condensed from the gas stream, the liquid carbon dioxide is subsequently vaporized.

[0043] The carbon dioxide recovery unit 20 selectively removes the carbon dioxide from the flue gas 17 and recovers it in the form of a carbon dioxide-rich product 25 for further use in the production of the methanol synthesis feed 8. The offgas 27 includes the components of the flue gas 17 that have not been separated off, especially inert gases, for instance nitrogen or argon, but also oxygen and water that has not been separated off. By means of the offgas 27, gases are thus selectively discharged from the ATR system and process and hence unwanted accumulation is counteracted.

[0044] As noted above with reference to the embodiment of Figure 1, the ATR system 1 also includes an autothermal reformer unit 30. The autothermal reformer unit 30 is configured to receive the preheated hydrocarbon feed 15 and oxygen 21 and convert it to a syngas product 25. In embodiments, the preheated hydrocarbon feed 15 and oxygen 21 react in an oxidation section of the autothermal reformer unit 30 and the reaction product then passes through a bed of reforming catalysts. The reaction can occur over a broad temperature range between about 350°-850°C and at a pressure of from about 25-50 bar. The reaction is endothermic, and the heat of reaction is provided by the combustion of oxygen 21 with the preheated hydrocarbon feed 15. The temperature of the syngas product 25 at the exit of the autothermal reformer unit 30 may be between about 900°-l 100°C or between about 950°-l 100°C or between about 1000°-1075°C. The syngas product may include carbon monoxide, hydrogen, carbon dioxide, steam, residual methane and various other components, for example, nitrogen and argon.

[0045] In embodiments, the ATR system 1 is without (i.e., absent) a steam methane reformer upstream of the autothermal reformer unit 30. Therefore, there is no primary reforming unit and no primary reforming step.

[0046] As noted above, the ATR system 1 of this disclosure further includes an electrolysis unit 40 arranged to receive water (or steam) and produce a hydrogen product 45 and an oxygen product 47. The electrolysis unit 40 may include one or more electrolysis units, for example based on solid oxide electrolysis or electrolysis by alkaline cells or polymer cells. In embodiments, the electrolysis unit 40 is powered renewable energy or electricity so as not to emit carbon dioxide, or which is neutral in carbon dioxide emissions. Accordingly, the carbon dioxide emissions from the system per pound of syngas product is reduced as compared to conventional ATR systems.

[0047] In embodiments, the electrolysis unit 40 is operated such that some or all of the hydrogen produced in the unit is added to the syngas product 35 and the module of the resulting methanol synthesis feed is between 1.9-2.2 or between 2-2.1. As is well known to one skilled in the art, the module can additionally be adjusted to a desired value by the addition of the carbon dioxide-rich product 25. Moreover, some or all of the oxygen product 47 produced is added to the autothermal reformer unit 30 thereby reducing the size (or need) of the air separation unit 60.

[0048] As noted above, the ATR system 1 of this disclosure further includes a mixing unit 50 arranged to receive the syngas product 35, carbon dioxide-rich product 25 and hydrogen product 45 and combine and mix the syngas product 35, carbon dioxide-rich product 25 and hydrogen product 45 to produce a methanol synthesis feed 8. In some embodiments, the mixing unit 50 may be a mixing drum, an inline mixer or mixing point.

[0049] As noted above, the ATR system 1 of this disclosure may optionally include an air separation unit 60 arranged to receive an air stream and produce an oxygen stream 65. In some embodiments, the air separation unit 60 is operated such that some or all of the oxygen produced in the unit is added to the oxygen 21 fed to the autothermal reformer unit 30. In embodiments, the air separation unit 60 is powered by renewable energy or electricity so as not to emit carbon dioxide, or which is neutral in carbon dioxide emissions.

[0050] In further embodiments, the ATR system 1 of this disclosure may optionally include a shift conversion or ‘shifting’ section (not shown) arranged to receive the syngas product 35 from the autothermal unit 30 and convert it to a shifted syngas product. The shift conversion section can include a high temperature shift reactor, a low temperature shift reactor, a first shift reactor, a final shift reactor, or any combination thereof. The shift conversion section can include cooling upstream and / or downstream of the high temperature shift reactor, the low temperature shift reactor, or both, where the heat removed can be transferred either directly or indirectly to another process stream of the system.

[0051] After the syngas generation is complete in the autothermal reformer unit 30, the syngas product 35 may be subjected to water gas shifting in the shift conversion section to produce the shifted syngas product via a water gas shift reaction. The shifting can be affected via any suitable methods known in the art. For example, shifting can comprise high temperature shift, low temperature shift, or both. In an embodiment, the syngas product 35 can be partially cooled at a first cooling step or unit(s) to produce a cooled reformer product which is then introduced into a high temperature shift reactor(s) where additional hydrogen is formed by shifting water and carbon monoxide to produce carbon dioxide and additional hydrogen via the water gas shift reaction to provide a high temperature shifted stream. The high temperature shift may be performed at a temperature of between about 300°-450°C and at a pressure of between about 25-50 bar.

[0052] Shift conversion section can further include cooling of the high temperature shifted stream in a second cooling step or unit(s) whereby the stream is cooled to provide cooled, high temperature shifted stream. Further completion of the shift reaction can be conducted by introducing cooled, high temperature shifted stream into a low temperature shift reactor. In embodiments, the low temperature shift can be performed at a temperature of between about 200°-300°C and / or a pressure of between about 25-50 bar to provide a low temperature shifted product stream.

[0053] A third cooling step can be employed to reduce the temperature of the low temperature shifted product stream to provide a cooled, shifted syngas product. In embodiments, the shifted syngas product may have a temperature suitable for feeding to the hydrogen purification unit 40, such as a temperature between ambient temperature and 100°C.

[0054] In another embodiment the present disclosure is directed to a methanol synthesis plant. With reference to Figure 2, the methanol synthesis plant 200 includes an ATR system 1 as described above and a methanol synthesis section 210. In further embodiments, the methanol synthesis plant may include a methanol purification section 220. It will be appreciated by those of skill in the art that this is a very simple schematic diagram and that an actual system may include additional sections and units of a standard type capable of heating, chilling, compressing, condensing, pumping, various types of separation and / or fractionation, as well as monitoring of pressures, temperatures, flows, and the like.

[0055] In embodiments, as described above the ATR system 1 is arranged to receive a hydrocarbon feed 5 and convert it to a methanol synthesis feed 8.

[0056] The methanol synthesis plant 200 further includes a methanol synthesis section 210 arranged to receive the methanol synthesis feed 8 and convert it to a methanol product stream 215 including low carbon methanol in one or more methanol synthesis reactors or catalyst beds for carrying out the methanol synthesis.

[0057] In some embodiments, after the reforming is complete, the methanol synthesis feed 8 can be cooled to near ambient temperature to condense water out and provide a largely dry gas for the methanol synthesis. The pressure of the largely dry gas can be increased to a desired methanol synthesis reactionpressure, which can be, for example, from about 1000-3000 psia, via one or more compressors. Thus, in some embodiments, the methanol synthesis section 210 can be operable to cool the methanol synthesis feed 8, condense water out from the feed 8, compress the feed 8, heat the feed 8, form low carbon methanol from the feed 8 in a methanol synthesis reactor, or a combination thereof. Methanol synthesis section 210 can thus further include a cooling apparatus to effect cooling and the condensing of water from the methanol synthesis feed 8; a compression apparatus operable to compress the methanol synthesis feed 8; and a heating apparatus operable to heat the methanol synthesis feed 8 for introduction into the methanol synthesis reactor.

[0058] As noted above, the methanol synthesis section 210 of this disclosure can include one or more methanol synthesis reactors or catalyst beds for carrying out methanol synthesis. The number and placement of methanol synthesis reactors is generally known to those skilled in the art. For example a methanol synthesis reactor may be 1-pass methanol synthesis reactor with a second compressor for recycle of a gas recycle stream 217 to the hydrocarbon feed preheating section 10, a 1-pass methanol synthesis reactor followed by a methanol synthesis reactor with a second compressor for recycle of the gas recycle stream 217 to the hydrocarbon feed preheating section 10, 2 methanol synthesis reactors in series within the recycle loop, or any of a variety of other configurations for methanol synthesis known to those of skill in the art.

[0059] Accordingly, the methanol synthesis section 210 can include a recycle compressor operable to recycle a gas recycle stream 217 containing unconverted syngas from the methanol reactor to the hydrocarbon feed preheating section 10. In embodiments, all or a portion of the recycle gas stream 217 may be introduced into hydrocarbon feed preheating section 10. In other embodiments a portion of the recycle gas stream 217 may be withdrawn via fuel export line 219.

[0060] As noted above, the methanol synthesis plant 200 of this disclosure can further include a methanol purification section 220. The methanol purification section 220 can be operable to receive the methanol product stream 215 and remove a low carbon methanol product 225 from the methanol product stream 215 as well as remove one or more components (e.g., light ends, heavy byproducts, water, or a combination thereof) from the low carbon methanol product 225.

[0061] Accordingly, in embodiments, the methanol purification section 220 can include a methanol separation apparatus, a light ends removal apparatus, a heavy byproducts separation apparatus, a methanol / water separation apparatus, associated heating, cooling, and / or a compressing apparatus, or a combination thereof, as described further below.

[0062] As noted above, the methanol purification section 220 can comprise a cooling apparatus. For example, cooling may be utilized downstream of the methanol synthesis reactor. In such embodiments, the methanol product stream 215 is cooled to near ambient temperature, where the low carbon methanol product and formed water from the reaction condenses.

[0063] As noted above, the methanol purification section 220 can comprise methanol recovery. In embodiments, methanol recovery is affected by a gas / liquid separator operable to separate the water and low carbon methanol condensed from cooling of the methanol product stream 215.

[0064] As noted above, the methanol purification section 230 can comprise separating a low carbon methanol product 225 from the methanol product stream 215. Any suitable separations can be utilized. The temperature in the purification section for separating the low carbon methanol 225 from the methanol product stream 215 is generally about 150°C or lower. In embodiments, separating low carbon methanol from the methanol product stream 215 further comprises removing light ends, heavy byproducts, and / or water to purify the low carbon methanol product 225.

[0065] In embodiments, separating low carbon methanol from the methanol product stream further comprises removing light ends from the low carbon methanol at 140°C. In embodiments, a degassing column is utilized at I40°C to separate low carbon methanol from light gases. Heat may be introduced to affect this light ends removal.

[0066] In embodiments, separating low carbon methanol from the methanol product stream 215 further comprises separating heavy byproducts. Hydrocarbon and higher alcohol byproducts that are formed in the methanol synthesis reaction can be separated by fractionation. These heavy byproducts can be taken out either as a side draw from either the light ends removal apparatus (e.g., a degassing column) utilized at light ends removal or from a methanol / water separation apparatus (e.g., a methanol purification tower) at methanol / water separation, or by a top or bottom product from a separate distillation tower. For example, a methanol stream from light ends removal can be introduced into a heavy byproducts separation apparatus wherein heavy byproducts can be removed from the methanol stream. Heat may be introduced or removed to affect this heavy byproducts removal,

[0067] In embodiments, separating low carbon methanol from the methanol product stream 215 further comprises separating low carbon methanol and water at methanol / water separation. In embodiments, low carbon methanol and water are distilled to purify low carbon methanol, and thus provide a purified low carbon methanol product 225 and water 227. Where sufficiently free from detrimental contaminants or trace chemistry modifiers, such as NaOH, water 227 can be recycled to a shift reactor(s) for shifting and / or for steam generation. Alternatively, water 227 can be cleaned prior to recycle. Methanol / water separation can be affected in a single fractionating tower (e.g., distillation column) or multiple towers (e.g., multiple distillation columns) for heat integration purposes. Heat may be introduced or removed to affect this methanol / water separation in embodiments.EXAMPLE

[0068] A simulation on Aspen was performed to determine the performance of the ATR system of the present disclosure in a 5000 MTPD Methanol synthesis plant. The results are shown below in Table 1.Table 1

[0069] While various embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The embodiments described herein are exemplary only and are not intended to be limiting. Many variations and modifications of the subject matter disclosed herein are possible and are within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, RL and an upper limit, Ru is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=Ri+k*(Ru-RL), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, z.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, ... 50 percent, 51 percent, 52 percent, ... , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc.

[0070] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an embodiment of the present disclosure. Thus, the claims are a further description and are an addition to the embodiments of the present disclosure. The discussion of a reference is not an admission that it is prior art to the present disclosure, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

Claims

CLAIMSWhat is claimed is:

1. An ATR system for the production of a methanol synthesis feed from a hydrocarbon feed, the ATR system comprising: a hydrocarbon feed preheating section arranged to receive the hydrocarbon feed and apply thermal energy to the hydrocarbon feed to produce a preheated hydrocarbon feed and a flue gas; a carbon dioxide recovery unit arranged to receive the flue gas and separate carbon dioxide from the flue gas to produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; an autothermal reformer unit arranged to receive the preheated hydrocarbon feed and oxygen and produce a syngas product; an electrolysis unit powered by renewable energy or electricity and arranged to receive water and produce an oxygen product and a hydrogen product; and a mixing unit operable to receive the syngas product, the carbon dioxide-rich stream and the hydrogen product and combine and mix the syngas product, the carbon dioxide-rich stream and the hydrogen product to produce the methanol synthesis feed.

2. The ATR system of claim 1, further comprising an air separation unit powered by renewable energy or electricity and arranged to receive an air stream and produce an oxygen stream.

3. The ATR system of claim 2, wherein the oxygen fed to the autothermal reformer comprises the oxygen product, the oxygen stream or a mixture thereof.

4. The ATR system of claim 1, wherein the hydrocarbon feed preheating section is further operable to adjust the pressure of the hydrocarbon feed.

5. The ATR system of claim 1, wherein the hydrocarbon feed preheating section is further operable to remove one or more contaminants from the hydrocarbon feed.

6. The ATR system of claim 1, wherein the ATR system is absent a steam methane reformer upstream of the autothermal reformer unit.

7. The ATR system of claim 1, wherein the carbon dioxide recovery unit comprises a gas scrubbing apparatus.

8. A process for producing a methanol synthesis feed from a hydrocarbon feed comprising: supplying the hydrocarbon feed to a hydrocarbon feed preheating section to produce a preheated hydrocarbon feed and a flue gas; supplying the flue gas to a carbon dioxide recovery unit to separate carbon dioxide from the flue gas and produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; supplying the preheated hydrocarbon feed and oxygen to an autothermal reformer unit to produce a syngas product; and supplying the syngas product, the carbon dioxide-rich stream and a hydrogen product produced by an electrolysis unit powered by renewable energy or electricity to a mixing unit to combine and mix the syngas product, the carbon dioxide rich stream and the hydrogen product and produce the methanol synthesis feed.

9. The process of claim 8, wherein the electrolysis unit further produces an oxygen product and wherein the oxygen supplied to the autothermal reformer unit comprises the oxygen product.

10. The process of claim 9, wherein the process further comprises supplying air to an air separation unit to produce an oxygen stream and wherein the oxygen supplied to the autothermal reformer unit further comprises the oxygen stream.

11. The process of claim 8, wherein the air separation unit is powered by renewable energy or electricity.

12. A methanol synthesis plant comprising: the ATR system of claim 1 and a methanol synthesis section arranged to receive the methanol synthesis feed and convert it to a methanol product stream comprising low carbon methanol.

13. The methanol synthesis plant of claim 12, wherein the methanol synthesis section comprises one or more methanol synthesis reactors or catalyst beds for carrying out methanol synthesis of the methanol synthesis feed and optionally a cooling apparatus, a heating apparatus, a compressing apparatus or any combination thereof.

14. The methanol synthesis plant of claim 12, further comprising a methanol purification section arranged to receive the methanol product stream and produce a purified low carbon methanol product.

15. A process for producing a low carbon methanol product from a hydrocarbon feed comprising:supplying the hydrocarbon feed to a hydrocarbon feed preheating section to produce a preheated hydrocarbon feed and a flue gas; supplying the flue gas to a carbon dioxide recovery unit to separate carbon dioxide from the flue gas and produce a carbon dioxide-rich product and an offgas containing a substantially reduced amount of carbon dioxide; supplying the preheated hydrocarbon feed and oxygen to an autothermal reformer unit to convert it to a syngas product; and supplying the syngas product, the carbon dioxide rich stream and a hydrogen product produced by an electrolysis unit powered by renewable energy or electricity to a mixing unit to combine and mix the syngas product, the carbon dioxide rich stream and the hydrogen product and produce a methanol synthesis feed; and supplying the methanol synthesis feed to a methanol synthesis section to convert the methanol synthesis feed to a methanol product stream comprising the low carbon methanol product.

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