Recycling of by-products to provide green hydrogen stream for methanol to jet fuel processes

Abstract

In a methanol-to-jet fuel combination unit, hydrogen is needed in a plurality of different processes including oligomerization. The hydrogen is produced by steam methane reforming and autothermal reforming. Higher efficiency is provided by increasing the amount of hydrogen available by passing off-gas streams from columns, including demethanizers, depropanes, and flash stripping columns, to a reforming reactor.

Description

[0001] This field relates to the conversion of olefins into distillates. This field can particularly involve the use of byproducts to produce hydrogen. Background Technology

[0002] Molecular sieves, such as microporous crystalline zeolites and non-zeolite catalysts, particularly aluminosilicate silica (SAPO), are known to promote the conversion of oxygen-containing compounds such as methanol into light olefins. The efficient methanol-to-olefins (MTO) process can convert oxygen-containing compounds into light olefins, which are typically considered for use in plastics production. The light olefins produced by the MTO process are highly concentrated with ethylene and propylene.

[0003] The ethanol dehydration process involves the dehydration of ethanol molecules to produce ethylene and water. The process of converting ethanol to ethylene is inherently endothermic, and the heat from this endothermic process is typically provided to the adiabatic reactor by a flame heater.

[0004] Ethylene can oligomerize into olefins, such as C4, C6, and C8 olefins. Propylene can oligomerize into olefins, such as C6, C9, and C12 olefins. Olefin oligomerization is the process of oligomerizing smaller olefins into larger olefins. More specifically, it can convert olefins (including oligomeric olefins) into distillates (including products from the jet fuel and diesel range). Oligomeric distillates can be saturated for use as transportation fuels.

[0005] Jet fuel is one of the few petroleum fuels that cannot be easily replaced by electric motor systems because it requires high energy output to fuel aircraft, which electric motors cannot provide. Jet fuel has a final boiling point specification of less than 300°C according to ASTM D86. In some regions, there are currently significant incentives for green jet fuel.

[0006] The oligomerization unit requires hydrogen to meet the requirements of sustainable jet fuel. An improved method is provided to recycle hydrogen-rich exhaust gas streams to supplement hydrogen produced during reforming.

[0007] definition

[0008] The term "connectivity" refers to the operative permission for fluid flow between enumerated components, which can be characterized as "fluid connectivity".

[0009] The term "downstream connectivity" means that in downstream connectivity, at least a portion of the fluid flowing toward the body can be operatively flowed from the object with which it is fluidly connected.

[0010] The term "upstream connectivity" means that at least a portion of the fluid flowing out of the main body can be operatively directed to an object in fluid communication with it.

[0011] The term "direct connection" means that fluid flow from an upstream component enters a downstream component without passing through any other intermediary container.

[0012] The term "indirect connection" refers to fluid flow from an upstream component entering a downstream component after passing through an intermediary container.

[0013] The term "bypass" means that an object is disconnected from the downstream entity at least within the scope of the bypass.

[0014] As used herein, the terms “major” or “most” mean greater than 50%, appropriately greater than 75%, and preferably greater than 90%.

[0015] The term "tower" refers to one or more distillation columns used to separate one or more components with different volatility. Unless otherwise specified, each column includes a condenser at the top of the column for condensing a portion of the overhead feed and returning it to the top of the column, and a reboiler at the bottom of the column for vaporizing a portion of the bottom feed and returning it to the bottom of the column. The feed to the column can be preheated. The top pressure is the pressure of the vapor at the top of the column at the vapor outlet. The bottom temperature is the liquid temperature at the bottom outlet. Top and bottom lines refer to the net lines from any downstream reflux or reboiler to the column. Stripping columns may omit the reboiler at the bottom of the column and instead provide the heating requirement and power for separating from a fluidized inert medium such as steam. Stripping columns typically feed from the top tray and remove the main product from the bottom.

[0016] As used herein, the term "separator" means a vessel having an inlet and at least one top vapor outlet and a bottom liquid outlet, and may also have an outlet for an aqueous feed stream from a boot. A flash tank is a type of separator that can be connected downstream of a separator capable of operating at higher pressures. As used herein, the term "boiling point temperature" means the atmospheric equivalent boiling point (AEBP) calculated from the observed boiling temperature and distillation pressure, as provided in Appendix A7 of ASTM D1160, entitled "Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures".

[0017] As used herein, the term "true boiling point" (TBP) refers to a test method conforming to ASTM D-2892 for determining the boiling point of a substance. ASTM D-2892 is used to produce standardized masses of liquefied gases, distillate fractions, and residues for which analytical data is available, and to determine the yield of these fractions by both mass and volume. The relationship between distillation temperature and mass% is obtained using fifteen theoretical plates in a column with a reflux ratio of 5:1 based on this mass and volume. picture .

[0018] As used herein, the terms “T5,” “T90,” or “T95” refer to the temperatures at which 5%, 90%, or 95% of a sample by mass (as the case may be) boil using ASTM D-86 or TBP, respectively.

[0019] As used in this article, the term “initial boiling point” (IBP) refers to the temperature at which a sample begins to boil using ASTM D-7169, ASTM D-86, or TBP (as applicable).

[0020] As used in this article, the term “endpoint” (EP) refers to the temperature at which a sample is brought to a complete boil using ASTM D-7169, ASTM D-86, or TBP (as applicable).

[0021] As used herein, the term "diesel" means hydrocarbons that boil in the following ranges: IBP between about 125°C (257°F) and about 175°C (347°F), or T5 between about 150°C (302°F) and about 200°C (392°F), and "diesel fractionation point," including T95 between about 343°C (650°F) and about 399°C (750°F) using the TBP distillation method, or T90 between 280°C (536°F) and about 340°C (644°F) using ASTM D-86. The term "green diesel" means diesel containing hydrocarbons not derived from fossil fuels.

[0022] As used herein, the term "jet fuel" refers to a hydrocarbon that boils in the T10 range between about 190°C (374°F) and about 215°C (419°F) and whose endpoint is between about 290°C (554°F) and about 310°C (590°F). The term "green jet fuel" refers to a jet fuel that contains hydrocarbons not derived from fossil fuels.

[0023] As used herein, the terms “major” or “most” mean greater than 50%, appropriately greater than 75%, and preferably greater than 90%.

[0024] As used herein, the term “rich component stream” means a rich component stream exiting a container that has a higher component concentration than the feed into the container, and preferably higher than all other streams exiting the container.

[0025] As used herein, the term "lean component stream" or "lean stream" means a lean stream exiting a container that has a lower component concentration than the feed into the container, and preferably lower than all other streams exiting the container.

[0026] As used herein, the term “rich in” means greater than 50%, appropriately greater than 75%, and preferably greater than 90%.

[0027] As used herein, the term "separator" refers to a vessel having an inlet and at least one top vapor outlet and a bottom liquid outlet, and may also have an outlet for an aqueous feed stream from a boot. A flash tank is a type of separator that can be connected downstream to a separator capable of operating at higher pressures. Detailed Implementation

[0028] A method for converting methanol into jet fuel is provided. The method can begin at least partially with methanol derived from a biological source, and other methanol can be derived from a petroleum source. The methanol is fed to a methanol-to-olefins reactor to produce a light olefins stream primarily containing ethylene and propylene but with some impurities, including higher molecular weight olefins, alkanes, carbon dioxide, and hydrogen. The light olefins stream is treated in a light olefins recovery process, in which dried liquid and vaporized olefin products are fractionated and fed to an oligomerization process, and then to a hydrogenation stage to produce jet fuel, as well as renewable diesel and naphtha streams. It has been found that, in addition to exhaust gas streams and other waste streams, the diesel and naphtha streams can also be fed to a steam reformer or an autothermal reformer to produce hydrogen that can be used in this method.

[0029] The disclosed methods and apparatus relate to the production of liquid fuels from carbon dioxide and hydrogen. The method includes reacting a mixture of carbon dioxide and hydrogen to produce methanol, carbon monoxide, and water. Methanol is contacted with an MTO catalyst to produce an olefin stream. The olefin stream is oligomerized using an oligomerization catalyst to produce an oligomeric olefin stream containing jet fuel, diesel fuel, and alkanes. The oligomeric olefin stream is separated into (1) a liquid fuel stream and (2) an alkane stream. A syngas stream containing carbon oxides and hydrogen is produced by: (1) reforming the alkane stream with steam in a steam reformer, an autothermal reformer, or a dry reformer; or (2) partially oxidizing the alkane stream.

[0030] The conversion of methanol to liquid fuel streams such as sustainable aviation fuel (SAF) is highly selective, but the light and heavy byproducts of the reaction must be disposed of. One way to improve the overall selectivity of CO2 for liquid fuel streams (e.g., jet fuel composites) (and reduce carbon intensity) is through CO2-to-syngas routes, such as reforming (steam reforming, autothermal reforming, or dry reforming) or partial oxidation, allowing the heavier hydrocarbons to be recycled. The resulting syngas can then be recycled back to the methanol synthesis unit, thereby increasing the jet fuel yield of CO2-to-jet fuel facilities.

[0031] Excess oxygen from the hydrolyzer can be introduced into the partial oxidation reactor to convert the byproducts into syngas, which can then be used as a ready-made feedstock for the methanol synthesis unit.

[0032] The methane and hydrogen produced by this method can be mixed with CO2 and reacted without the use of steam. This requires a non-precious metal-based catalyst developed by Linde and BASF. The resulting syngas can be used to produce methanol. It is also possible to process small amounts of other light hydrocarbons in this manner. The advantage of this route is that it produces syngas without requiring hydrogen from an electrolyzer, the most energy-intensive part of the CO2-to-jet fuel complex.

[0033] Liquid byproducts from the MTJ complex are mixed with oxygen from the hydrolysis unit and reacted over a catalyst to convert hydrocarbons into CO. CO2 can be co-fed to increase the overall CO yield. The process is exothermic once a sufficiently high temperature is reached.

[0034] There are two alternative solutions to this method:

[0035] (1) Steam reforming with CO2 and steam at high temperatures will produce a synthesis gas mixture that can be directly fed into methanol synthesis. This is an endothermic process and therefore requires a large amount of external heat.

[0036] (2) Autothermal reforming combines partial oxidation and steam reforming. Oxygen, steam, and CO2 from the hydrolysis unit react over a catalyst to produce a suitable syngas mixture for conversion to methanol. Methane and hydrogen (and possibly ethane) from the MTJ exhaust stream are mixed with CO2 to form a syngas mixture of H2 and CO. This is an endothermic process, but can act as a radiator from other exothermic processes.

[0037] A third alternative is dry reforming. Methane and carbon dioxide react over a catalyst in an endothermic process to form a syngas mixture of H2 and CO.

[0038] The stream exiting the propane stripper in the oligomerization process is fed to a reactor, where it is converted into syngas via steam reforming, partial oxidation, autothermal reforming, or dry reforming. The syngas is then fed to the methanol synthesis unit. If partial oxidation or autothermal reforming is chosen to produce syngas, air or oxygen must also be supplied, and additional steam can be extracted from the reactor for use elsewhere in the facility. If steam reforming is chosen to produce syngas from ethane / propane, a steam feed (which can be entirely supplied by the methanol-to-jet fuel process) and an energy input (which can be partially supplied by steam from the methanol-to-jet fuel process) will also be required.

[0039] Liquid fuels can be produced from carbon dioxide and hydrogen through the following steps:

[0040] (a) React a mixture of carbon dioxide and hydrogen to produce methanol, carbon monoxide and water;

[0041] (b) Contact the methanol with an MTO catalyst to generate an olefin feed stream;

[0042] (c) Oligopolymerizing the olefin stream with an oligomerization catalyst to produce an oligomeric olefin stream comprising jet fuel, diesel fuel and alkanes;

[0043] (d) Separating the oligoolefin stream into (1) a liquid fuel stream and (2) an alkane stream; and

[0044] (e) A synthesis gas stream containing carbon oxides and hydrogen is generated by the following:

[0045] (1) The alkane stream is reformed with steam in a steam reforming reactor, an autothermal reforming reactor, or a dry reforming reactor; or

[0046] (2) The alkane stream is partially oxidized.

[0047] The method for producing liquid fuels from carbon dioxide and hydrogen may also include the following steps:

[0048] (a) Reacting a mixture of carbon dioxide and hydrogen to produce a crude methanol stream containing methanol, water and other contaminants, the other contaminants including one or more of hydrogen, CO, CO2, methane, ethanol and other oxygenated hydrocarbons.

[0049] (b) The crude methanol stream is purified by distillation to remove light contaminants into a first waste gas stream; heavy contaminants and water are removed into a second heavy waste stream; and a refined methanol stream is produced.

[0050] (c) Contact the refined methanol stream with an MTO catalyst to produce a crude olefin stream containing ethylene, propylene, butene and other contaminants, including one or more of hydrogen, CO, CO2, methane, dimethyl ether, ethanol and other oxygenated hydrocarbons.

[0051] (d) The crude olefin stream is purified by distillation to remove the light fraction to the third waste gas stream; then water absorption is performed to remove heavy oxygenated hydrocarbons and water extraction is performed to remove dimethyl ether to the DME (dimethyl ether) recycling stream; and one or more refined olefin streams are produced.

[0052] (e) Using one or more reaction vessels, the refined olefin stream is reacted with one or more oligomeric catalysts to produce a crude oligomeric olefin stream comprising oligoolefins with a carbon length between 4 and 24 carbons; and contaminants comprising one or more of hydrogen, methane, and alkanes lighter than pentane.

[0053] (f) The crude oligoolefin stream is fractionated by distillation to remove hydrogen and light alkanes into (1) the fourth waste gas stream, (2) the light oligoolefin recycling stream and (3) the refined oligoolefin stream containing olefins with carbon lengths between 12 and 24 carbons.

[0054] (g) The refined oligoolefin stream is reacted with hydrogen in the presence of a hydrogenation catalyst to saturate the olefins into alkanes to produce a crude jet fuel stream.

[0055] (h) The crude jet fuel stream is fractionated by distillation to remove excess hydrogen and light hydrocarbons into (1) the fifth exhaust stream, (2) the sixth exhaust stream containing naphtha, (3) the seventh exhaust stream containing diesel and (4) the liquid fuel containing jet fuel.

[0056] (i) A recycled syngas feed stream containing carbon oxides and hydrogen is generated by:

[0057] (1) In a steam reforming process, an autothermal reforming process, or a dry reforming process, one or more waste gas streams in the waste gas stream are reformed with steam; or

[0058] (2) Partially oxidizing one or more of the waste gas streams; and

[0059] (j) The recycled synthesis gas stream is fed together into the methanol synthesis process of step A.

[0060] One or more of the waste gas streams may also be reacted with oxygen in a partial oxidation reactor to produce a second recycle syngas stream containing CO and hydrogen.

[0061] The reaction in step (i) can also be carried out by reacting one or more waste gas streams with oxygen and steam in an autothermal reactor to produce a third recycle synthesis gas stream containing CO and hydrogen.

[0062] The reaction in step (i) can also be carried out by reacting the sixth waste gas stream with steam in a steam reforming process; by reacting the seventh waste gas stream with steam in a steam reforming process; or by partial oxidation, and the resulting recycled syngas stream is thermally integrated with the fractionation process in step (j) to provide some or all of the energy required for distillation.

[0063] Hydrogen for steps (a) and / or (g) may be generated by a water electrolysis unit and / or oxygen for autothermal reforming may be generated by a water electrolysis unit.

[0064] In the case where the reaction in step (i) is carried out by partial oxidation, the oxygen used for partial oxidation can be generated by a water electrolysis unit.

[0065] When the reaction in step (i) is carried out using steam in a steam reforming process, one or more exhaust gas streams fed into the steam reforming reactor may contain between 10% and 50% by weight of propane. The reaction in step (i) may also be carried out using a dry reforming process.

[0066] The water electrolysis unit (electrolyzer) produces hydrogen and oxygen from water.

[0067] In this disclosure, methanol is supplied to a process that can be carried out at different locations. The resulting methanol is then contacted with an MTO catalyst to produce an olefin feed stream.

[0068] picture The block flow shown picture The most relevant part of process scheme 200 provides hydrogen to the process as needed. Waste gas stream 202 is fed from several different towers, including oligomerization and LORP units, to pre-reforming section 205, where stream 210 is fed to steam methane reforming unit 215, and stream 204 is fed to both pre-reforming section 205 and steam methane reforming unit 215. A portion 220 of the waste gas can be used to fuel steam methane reforming unit 225 via line 225, and enters pressure swing adsorption unit 250 via line 270 for separation to provide hydrogen 260. Furthermore, hydrogen-rich waste gas stream 250 is added to the effluent 245 of water-gas shift unit 235.

[0069] The exhaust gas from Tower 202 comes from picture The net overhead vapor streams of several process units (not shown) include a demethanizer, a depropanizer, a flash stripper, and a jet fractionator. Depropanizer exhaust gas is the preferred feed, and flash stripper or demethanizer exhaust gas is the preferred feed to the pressure swing adsorption (PSA) unit. Pre-reforming removes components heavier than methane from the feed gas and decomposes them into methane. This prevents over-coking in the steam methane reforming (SMR) reactor. SMR uses a catalyst at very high temperatures to convert methane and water into syngas (a mixture of carbon monoxide and hydrogen). This is a highly endothermic reaction, therefore requiring an external fuel stream to provide the heat of reaction.

[0070] The water-gas shift reaction (PSA) takes place at a much lower temperature. This shift involves reacting CO with additional water to produce CO2 and additional hydrogen. This is a mildly exothermic reaction. In the pressure swing adsorption (PSA) process, the product from the PSA reactor is processed, which contains a mixture of hydrogen, CO2, CO, and unconverted methane. The PSA product gas is high-purity hydrogen, and the tail gas contains CO2, CO, and unconverted methane, which is used as fuel for the SMR reactor.

[0071] If the CO and unconverted methane from the PSA are insufficient to provide the necessary heat of reaction in the SMR, additional fuel gas can be supplied from the exhaust gas from the tower. If the exhaust gas is hydrogen-rich, it is directed to the PSA for hydrogen recovery. If the exhaust gas is not hydrogen-rich, it will be fed directly into the SMR reactor as fuel.

[0072] Specific implementation plan

[0073] While the following description is presented in conjunction with specific embodiments, it should be understood that the description is intended to be illustrative and not to limit the scope of the foregoing description and the appended claims.

[0074] A first embodiment of the present invention is a method for providing hydrogen in a process for producing jet fuel from methanol, the method comprising feeding a waste gas stream to a reforming section to generate a gas stream, conveying a hydrogen-rich waste gas stream to be combined with the gas stream to provide a hydrogen-enhanced gas stream, and purifying the hydrogen-enhanced gas stream to generate a hydrogen stream. An embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the waste gas stream is first fed to a pre-reforming reactor within the reforming section and then to a water-gas shift reactor. An embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein after passing through the water-gas shift reactor, the gas stream is fed to a pressure swing adsorption unit to generate a hydrogen stream. An embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the waste gas stream is discharged from at least one tower selected from a demethanizer, a depropanizer, a flash stripper, or a jet fractionator, or combinations thereof. One embodiment of the invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the pressure swing adsorption unit treats a mixture of hydrogen, carbon dioxide, carbon monoxide, and unconverted methane. One embodiment of the invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the pressure swing adsorption unit produces a tail gas stream comprising carbon dioxide, carbon monoxide, and unconverted methane. One embodiment of the invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein a portion of the tail gas stream is supplied to supplement the fuel supply of a steam methane reforming reactor. One embodiment of the invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the tail gas stream is fed to the steam reforming reactor as fuel gas. One embodiment of the invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the tail gas stream contains at least 10 mol% hydrogen. One embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the waste gas stream contains at least 20 mol% hydrogen. Another embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the hydrogen stream contains at least 95 mol% hydrogen. Yet another embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in this paragraph, wherein the hydrogen stream contains at least 98 mol% hydrogen.One embodiment of the present invention is one, any, or all of the embodiments described above in this paragraph up to the first embodiment in paragraph 1, and further includes a control unit for measuring the hydrogen concentration in the waste gas stream, then sending the waste gas stream containing a hydrogen concentration below a predetermined value as fuel gas to the reforming section, and sending the waste gas stream to the pressure swing adsorption unit when the hydrogen concentration is above the predetermined level.

Claims

1. A method for providing hydrogen in a process for producing jet fuel from methanol, the method comprising: The hydrocarbon-rich waste gas stream is sent to a reforming reactor or a partial oxidation reactor to generate a gas stream; A hydrogen-rich waste gas stream is conveyed to be combined with the gas stream to provide a hydrogen-enhanced gas stream; as well as The hydrogen-enhanced gas stream is purified to produce a hydrogen stream.

2. The method according to claim 1, wherein the waste gas stream is first fed to a pre-reforming reactor and then to a water-gas shift reactor.

3. The method according to claim 2, wherein after passing through the water-gas shift reactor, the gas stream is sent to a pressure swing adsorption unit to purify the hydrogen-enhanced gas stream.

4. The method according to claim 1, wherein the hydrocarbon-rich waste gas stream originates from at least one tower selected from a dealkane tower and a jet fractionation tower or a combination thereof.

5. The method of claim 1, wherein the hydrogen-rich waste gas stream originates from at least one tower selected from a demethanizer and a stripping tower or a combination thereof.

6. The method of claim 3, wherein the pressure swing adsorption unit processes a mixture of hydrogen, carbon dioxide, carbon monoxide, and unconverted methane to generate the hydrogen feed stream.

7. The method of claim 3, wherein the pressure swing adsorption unit generates a tail gas stream comprising carbon dioxide, carbon monoxide and unconverted methane.

8. The method of claim 1, wherein a portion of the hydrocarbon-rich waste gas stream is conveyed to supplement the fuel supply to the reforming reactor or the partial oxidation reactor.

9. The method according to claim 7, wherein the tail gas stream is fed as fuel gas to a steam reforming reactor or a partial oxidation reactor.

10. The method of claim 1, wherein the hydrocarbon-rich gas stream is fed to a water-gas shift reactor after the reforming reactor or the partial oxidation reactor.

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