Green ethylene water recycling

Abstract

The present disclosure provides methods and systems for producing olefins, such as ethylene, including feeding a steam-alcohol mixture to a dehydration reactor and dehydrating the alcohol to form a reaction effluent comprising an olefin and water. The method includes quenching and separating the reaction effluent to recover a quenched effluent and a gaseous hydrocarbon comprising the olefin. The quenched effluent is separated to form a volatile organic stream and an aqueous organic effluent. Solids, hydrocarbons, or both can be removed from the quenched effluent, the aqueous organic effluent, or both. The method further includes one or both of feeding a portion of the aqueous organic effluent as the quenching medium or vaporizing a portion of the aqueous organic effluent, including water and hydrocarbon- containing compounds, to form a mixed dilution steam stream and a residual liquid, and diluting a vaporized oxygenate hydrocarbon feedstock with the mixed dilution steam stream to form a steam-oxygenate hydrocarbon mixture.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to methods for forming ethylene, propylene, and other olefins by dehydrating oxygenated hydrocarbons such as ethanol, propanol, butanol, and other oxygenated substances, including those prepared by green methods (from renewable resources). Embodiments of this disclosure further relate to the efficient utilization of water generated during the dehydration process. Background Technology

[0002] The process of producing olefins via alcohol dehydration generates a significant amount of water as a reaction product. Unfortunately, a large number of reaction byproducts are present, and these byproducts are generally considered to render the resulting water unsuitable for reuse due to scaling or other problems associated with them. Summary of the Invention

[0003] In one aspect, the embodiments disclosed herein relate to a method for producing ethylene. The method includes feeding a vapor-ethanol mixture into a dehydration reactor and dehydrating the ethanol in the dehydration reactor to form a reaction effluent containing ethylene and water. The method further includes quenching and separating the reaction effluent with a quenching medium containing water to recover the quenched effluent and the ethylene-containing gaseous stream, and then separating the quenched effluent to form a volatile organic stream and an aqueous organic effluent. During the method, solids, hydrocarbons, or both can be removed from the quenched effluent, the aqueous organic effluent, or both. The method further includes one or both of the following: feeding a portion of the aqueous organic effluent as the quenching medium used in the quenching and separation steps; or vaporizing a portion of the aqueous organic effluent, including water and hydrocarbon compounds, to form a mixed dilution vapor stream and residual liquid, and diluting the vaporized ethanol-containing feedstock with the mixed dilution vapor stream to form a vapor-ethanol mixture.

[0004] In another aspect, the embodiments disclosed herein relate to a method for producing olefins. The method includes feeding a vapor-alcohol mixture into a dehydration reactor and dehydrating the alcohol in the dehydration reactor to form a reaction effluent containing olefins and water. The method further includes quenching and separating the reaction effluent with a quenching medium containing water to recover the quenched effluent and gaseous hydrocarbons containing olefins, and then separating the quenched effluent to form a volatile organic stream and an aqueous organic effluent. During the method, solids, hydrocarbons, or both can be removed from the quenched effluent, the aqueous organic effluent, or both. The method further includes one or both of the following: feeding a portion of the aqueous organic effluent as the quenching medium used in the quenching and separation steps; or vaporizing a portion of the aqueous organic effluent, including water and hydrocarbon compounds, to form a mixed dilution vapor stream and residual liquid, and diluting the vaporized oxygenated hydrocarbon feedstock with the mixed dilution vapor stream to form a vapor-oxygenated hydrocarbon mixture.

[0005] In another aspect, the embodiments disclosed herein relate to a system for producing filtered water from green ethylene process reaction water containing oxygenated hydrocarbons, ethanol, light hydrocarbons, and suspended solids. The system includes a flash or distillation stage to remove light hydrocarbons from the green ethylene reaction water to produce a water-rich stream, and a secondary treatment stage including a filter, membrane, or coalescer to remove at least some suspended solids or fouling or heavy oxygenated matter from at least a portion of the water-rich stream to produce an aqueous product stream. The system further includes an internal supply stage that vaporizes the aqueous product stream and feeds the resulting vaporized aqueous product stream as feed to a dehydration reactor. The resulting aqueous product stream is water-containing steam having a chemical oxygen demand (COD) of 5 to 200 mg / L and a suspended solids content of 5 to 200 mg / L.

[0006] In another aspect, the embodiments disclosed herein relate to a system for producing green ethylene. The system includes a feed preparation unit for processing and vaporizing an ethanol feedstock to produce vaporized ethanol. The system also includes a dehydration unit for receiving a mixture of vaporized ethanol and superheated steam, the dehydration unit containing a catalyst for dehydrating the alcohol to form a reaction effluent comprising ethylene, water, and reaction byproducts. Furthermore, the system includes a product purification unit configured to quench and separate the reaction effluent to form a crude ethylene product stream comprising a first portion of ethylene and reaction byproducts, and an aqueous effluent comprising a remaining portion of water and reaction byproducts. The system also includes an internal supply stream generation unit configured to receive the aqueous effluent and remove a second portion of the reaction byproducts to produce an aqueous product stream comprising water and remaining reaction byproducts, and an internal supply system for vaporizing at least a portion of the aqueous product stream and feeding it as a superheated steam mixture to the dehydration unit.

[0007] Other aspects and advantages will become apparent from the following description and the appended claims. Attached Figure Description

[0008] Figure 1 A block flow diagram of a system for producing olefins according to one or more embodiments disclosed herein is illustrated.

[0009] Figure 2 A simplified process flow diagram of a system for producing olefins according to one or more embodiments disclosed herein is shown.

[0010] Figure 3 A simplified process flow diagram of a portion of a system for producing olefins according to one or more embodiments of this document is shown. Detailed Implementation

[0011] The embodiments herein generally relate to methods and systems for producing olefins from alcohols. More specifically, the embodiments herein relate to methods and systems for producing “green” olefins from renewable resources. For embodiments requiring “green” certification, all steps according to the embodiments herein can be proven on bio-based feedstocks or bio-based intermediates and do not include any fossil-based feedstocks or intermediates.

[0012] Typically, the process configuration according to the embodiments herein includes four main unit operations. The first unit is the feed preparation unit. Feed preparation may include various operations, including desalination, dilution, heating, and other steps to prepare the feedstock for use.

[0013] The second unit is the dehydration unit (alcohol dehydration unit or oxygen-containing dehydration unit) for the production of olefins. The dehydration unit can be used to dehydrate, for example, alcohol feedstocks such as bioethanol or biobutanol to form olefins such as ethylene or butene. Other alcohols and bioethanol feedstocks, as well as other oxygen-containing hydrocarbons that can be dehydrated to form olefins, can also be used.

[0014] The third unit is the product purification unit. The product purification unit includes various unit operations to separate and recover the target olefin from the dehydration reaction effluent. The product purification unit may include various unit operations, including quenching systems, acid gas capture, byproduct separation, solids removal, and other steps for recovering and treating the reaction effluent to recover the desired olefin product stream.

[0015] The fourth unit is the internal supply stream purification unit. The dehydration process generates a significant amount of water and various byproducts. The method described herein utilizes the product water, which may be contaminated by byproducts, as an internal aqueous supply stream for various unit operations within one, two, or all of the feed preparation unit, dehydration unit, and product purification unit. The internal supply stream purification unit may include various unit operations to process the aqueous stream recovered from the product purification unit, thereby providing an aqueous or organic stream suitable for internal use in the alcohol-to-olefin process described herein.

[0016] Raw materials that can be used in the embodiments herein may include various alcohols, such as C2-C7 alcohols, including one or more of primary alcohols (such as ethanol), secondary alcohols (such as 2-butanol), and isools (such as isopropanol). In some embodiments, the alcohol feed may include two or more C2-C7 alcohols, fed alone or as a mixture. In other embodiments, the alcohol feed may include ethanol or a mixture of ethanol with one or more other alcohols. Primary alcohols that can be used in the embodiments herein may include ethanol, propanol, butanol, pentanol, hexanol, and heptanol. Secondary alcohols that can be used in the embodiments disclosed herein may include 2-butanol, 2-pentanol, 3-pentanol, 2-hexanol, and 3-hexanol, as well as other alcohols wherein the OH group is at the 2-, 3-, or 4-position. Isools that can be used in the embodiments may include isopropanol, isobutanol, isopentanol, isohexanol, and isoheptanol.

[0017] In various embodiments, the alcohols that can be used in the embodiments disclosed herein may include bioethanols, such as bio-derived ethanol, bio-derived propanol or isopropanol or bio-derived butanol. In some embodiments, bioethanols may be produced via fermentation. In other embodiments, bioethanols may be produced via a method involving the gasification of biomass into syngas followed by a modified Fischer-Tropsch synthesis. Bioethanols are feedstocks that can be derived from renewable resources such as corn, corn stalks, corn cobs, lignocellulose, sugarcane, sugar beets, and wheat.

[0018] To facilitate downstream separation, the feed alcohol can produce the target olefin with a boiling point lower than that of water.

[0019] The production of olefins according to the embodiments disclosed herein can be accomplished via the dehydration of alcohols. Catalysts that can be used in the embodiments disclosed herein include those active in the dehydration of alcohols to form olefins and water. Catalysts that can be used in the embodiments herein may include, for example, resin catalysts, such as sulfuric acid resins or hydrochloric acid resin catalysts. Other catalysts that can be used include various grades of alumina, silica, aluminum silicate, or other acidic catalysts with dehydration activity. By-product reactions may include the formation of light hydrocarbons (i.e., C1-C6 alkanes, including methane, ethane, propane, butane, etc.), methanol, aldehydes such as propionaldehyde or acetaldehyde, acetates such as ethyl acetate, and heavier alcohols (e.g., ethanol). Sec-butanol), 2-pentanone or other ketones such as acetone, diethyl ether or other dialkyl ethers, higher molecular weight oligomers and ethers, aromatics and coke, which often cause catalyst scaling.

[0020] Alcohol feedstocks can be provided as aqueous or anhydrous feedstocks. Anhydrous, as used herein, refers to a stream containing less than 0.5 wt% water. Other alcohol feedstocks that can be used in the embodiments disclosed herein may contain impurities such as water. For example, alcohols may contain a certain amount of water. Typically, water is removed from alcohols. However, since water is a byproduct of alcohol dehydration reactions, the alcohol feedstocks used in the embodiments disclosed herein may contain water as an impurity. Excessive water in the feedstock may lower reactor conversion equilibrium and may lead to increased reboiler load, but water as a feed impurity is acceptable in the systems described herein.

[0021] In some embodiments, the alcohol feed may include up to 40 wt% water; in other embodiments, up to 30 wt% water; in other embodiments, up to 20 wt% water; in other embodiments, up to 10 wt% water; in other embodiments, up to 5 wt% water; and in yet another embodiment, up to 2 wt% water. In other embodiments, the alcohol feed may be substantially pure alcohol or a mixture of alcohols. In other embodiments, the alcohol feed that can be used in the embodiments disclosed herein may contain 0.1 to 100 wt.% alcohol and 0 to 99.9 wt.% water. In other embodiments, the alcohol feed may contain 10 to 100 wt.% alcohol; in other embodiments, 25 to 100 wt.% alcohol; and in yet another embodiment, 50 to 95 wt.% alcohol. The amount of water that may be used in the catalytic reaction zone may depend on (1) the reaction equilibrium constant and (2) the strength / activity of the acid catalyst used for conversion. For example, activity can be maintained at higher water concentrations when shifting from a resin-type catalyst to a stronger sulfuric or hydrochloric acid concentration. When acidic resin catalysts move to larger amounts of water at high temperatures, they are more susceptible to loss of catalyst activity.

[0022] The aforementioned alcohol feedstock is fed into a feed preparation unit. The feed preparation unit may include one or more unit operations, including desalting, dilution, heating, distillation, reactor, and other steps to remove impurities and appropriately prepare a feedstock for use. For example, diluted alcohol feedstock or feedstock containing a large amount of water may be treated to remove a portion of the water or another impurity, such as by distillation or membrane separation, thereby providing an alcohol feedstock suitable for downstream processing.

[0023] The alcohol feedstock can be provided as an aqueous mixture. In other embodiments, the alcohol can be provided as an anhydrous feedstock or with a low (less than 10 wt%) water content. The provided alcohol may contain residual salts or material separating agents (such as benzene or other agents, wherein azeotropic distillation is used to purify the provided alcohol (ethanol) feedstock), as well as denaturants or other impurities. In such embodiments, the alcohol feedstock can be treated in a feed preparation unit to remove salts, separating agents, and / or denaturants before evaporation and feeding the alcohol into the reactor described herein. Desalination can minimize scaling of heat exchangers, heating coils, or reactor / catalyst, and desalination can be performed, for example, by passing the alcohol feedstock through a treatment system to remove salts (anions and cations) contained in the feedstock. Treatment systems that can be used herein may include anion exchange beds, cation exchange beds, mixed-bed ion exchange, alumina-based or iron-based adsorbent beds, lime softening, filtration, reverse osmosis, and other treatment techniques to remove salts contained in the feedstock. In some embodiments, the feedstock can be passed continuously through anion exchange beds and cation exchange beds in any order. In other embodiments, the feedstock can be diluted with an internally generated dilution water stream prior to desalination, such as by continuously passing the diluted feedstock through anion exchange beds and cation exchange beds in any order. If desired, material separating agents such as benzene can also be removed, for example via adsorption. However, dehydration catalysts are generally resistant to material separating agents and can be addressed via downstream treatment of the dehydration reactor. Similarly, dehydration catalysts can be resistant to hydrocarbon or alcohol denaturants and can be addressed via downstream treatment of the dehydration reactor.

[0024] The prepared alcohol feed can then be heated to feed the vaporized alcohol into the second unit. The vaporization of the alcohol feed can be carried out in the convection section of, for example, a furnace, boiler, heat exchanger, or electric heater. Indirect or direct heat exchange can be used.

[0025] In some embodiments, after the alcohol feedstock is vaporized, the alcohol feedstock may be combined with a superheated steam stream to provide a superheated alcohol-steam stream for feeding into the endothermic dehydration reactor. In some embodiments, the superheated steam is a mixed dilution steam stream, as further described below, derived from water vapor containing various dehydration reaction byproducts, wherein water streams are recovered in the product purification unit and the internal supply stream purification unit.

[0026] The amount of dilution steam used can depend on the alcohol feedstock and reactor configuration. Generally, the molar ratio of steam to alcohol in the dehydration reactor feed is between 0.5:1 and 1.5:1, such as between 0.7:1 and 1.3:1. In other embodiments, the mass ratio of steam to alcohol in the dehydration reactor feed is between 2.0:1 and 3.0:1, such as between about 2.4:1 and 2.8:1. By mass, the dehydration reaction can produce a reaction effluent with approximately twice the amount of water compared to the feed. The amount of dilution steam used can depend on the alcohol feedstock, dehydration catalyst, dehydration reaction conditions, steam temperature, and other factors. Generally, the superheated dilution steam should provide sufficient energy to the system to maintain catalytic activity in the endothermic dehydration reactor.

[0027] The dewatering reactors that can be used in the embodiments disclosed herein may include conventional fixed-bed reactors, bubbling-bed reactors, moving-bed reactors, and other types of dewatering reactors known in the art. The reactors that can be used in the embodiments disclosed herein may be used as stand-alone reactors or in combination with one or more reactors of the same or different types. Multi-reactor systems that can be used in the embodiments disclosed herein may include a series of reactors of the same type or reactors in parallel, or reactors of different types in series. Those skilled in the art will recognize that other types of reactors can also be used.

[0028] The reaction conditions in the dehydration reactor can depend on the alcohol being processed, the catalyst used, and other factors. For example, the reaction temperature can range from 50°C to 500°C, and the pressure can range from 0.01 to 20 MPa (gauge pressure). In some embodiments, the dehydration reactor temperature can range from a lower limit of 100°C, 125°C, 150°C, 175°C, 200°C, 225°C, 250°C, 275°C, 300°C, 325°C, or 350°C to an upper limit of 250°C, 275°C, 300°C, 325°C, 350°C, 375°C, 400°C, 425°C, 450°C, 475°C, or 500°C, wherein any lower limit can be combined with any upper limit. In some embodiments, the dehydration reaction pressure may be within the range of a lower limit of 0.1, 0.2, 0.3, 0.5, 1.0, 1.5 or 2.0 MPa (gauge pressure) to an upper limit of 1.0, 1.5, 2.0, 2.5, 3.0, 4.0 or 5.0 MPa (gauge pressure), wherein any lower limit may be combined with any upper limit.

[0029] After conversion in the dehydration unit, the resulting dehydration reactor effluent can be fed to the product purification unit. In some embodiments, the resulting dehydration reactor effluent may be initially cooled, such as in a feed / effluent exchanger, before being fed to the product purification unit.

[0030] Product purification units that may be used in the embodiments herein may include quenching towers or washing towers. A quenching tower contacts a quenching medium and cools the gaseous reaction effluent. Quenching can be carried out under conditions suitable for condensing and capturing water, oxygenated hydrocarbons (unreacted ethanol, oxygenated reaction byproducts), and any heavier hydrocarbons (oligomers, etc.) through the quenching medium, thereby producing a crude olefin stream and an aqueous effluent.

[0031] The product purification unit may also include one or more distillation columns, extractive distillation columns, or stripping columns to separate the olefin product from other components contained in the crude olefin stream. For example, the crude olefin stream may be compressed and fed to a first distillation column to separate heavier (higher boiling point) components from the crude olefin stream and recover them as bottom distillate. The resulting olefin-containing overhead distillate may be fed to a second distillation column or stripping column to remove lighter (lower boiling point) components contained in the crude olefin stream from the purified olefins recovered as bottom distillate and recover them as overhead distillate. Dryers, compressors, and compressor separators, as well as other components, may be used to remove and / or recover any water carried in the crude olefin stream.

[0032] The quenching medium that can be used in the embodiments herein includes water or an aqueous mixture. In some embodiments, the quenching medium may include an alkaline or amine component to absorb acidic gases contained in the reaction effluent. In other embodiments, the product purification unit may include a water scrubber (water quenching) unit followed by an alkaline scrubbing tower. In some embodiments, the water used as the quenching medium or in the alkaline scrubbing tower may be an aqueous stream derived from an internal supply stream purification unit.

[0033] The aqueous stream recovered from the product separation unit can be fed into an internal supply stream purification unit. The internal supply stream purification unit receives the aqueous effluent from a quench tower or water scrubber, as well as any other water that may be generated during olefin product recovery. The aqueous stream may include water and various reaction byproducts, as described above, including various oxygenated hydrocarbons, unreacted alcohols, sodium hydroxide, sodium carbonate, and possible polymers or oligomers formed from olefins or as byproducts of reactions with alkali agents, such as oligomers of aldehydes (e.g., acetaldehyde) or ketones (e.g., acetone) catalyzed by caustic agents.

[0034] To process the received aqueous stream, the internal supply stream purification unit may include various solids and hydrocarbon removal units, including filtration, biofilters, oxidation processes, photolysis, distillation or stripping columns, membrane separation units, membrane bioreactors, adsorption beds, coalescers, reverse osmosis units, or other various separation devices or combinations thereof, to recover an aqueous stream of sufficient purity for use in upstream units. The internal supply stream purification unit may generate, for example, a volatile organic stream containing volatile organic compounds present in the aqueous stream, a mixed water / organic feed stream, and a mixed water / organic discharge stream, wherein the mixed water / organic stream contains non-volatile organic compounds present in the aqueous stream. In some embodiments, the volatile organic stream may be used as a fuel gas feed stream, which may be combusted to generate heat or electricity for one or more of the various unit operations (boilers / steam generators, heaters / heating coils (radiation or convection), etc.) of the method for producing olefins described herein.

[0035] In some embodiments, the internal supply purification unit includes a solids / hydrocarbon removal unit and an effluent treatment tower. The solids / hydrocarbon removal unit may include a coalescer, a settling tank, a filter, or other unit operations or combinations of unit operations adapted to facilitate the separation of at least a portion of solids and at least a portion of hydrocarbons from the water. The solids / hydrocarbon removal unit may be located upstream of, downstream of, or both upstream and downstream of the effluent treatment tower.

[0036] Effluent treatment columns, which can be distillation or stripping columns, can be used to separate volatile organic compounds from water and heavier organic compounds contained in aqueous streams. The volatile organic compounds can be recovered from the effluent treatment column as overhead distillate and can be used as fuel gas feedstock for furnaces, heaters, or energy conversion units within a system or plant.

[0037] In some embodiments, in addition to the volatile organic compound overhead distillate, an alcohol-containing side stream can be withdrawn from the effluent treatment column. This alcohol-containing side stream can be combined with the alcohol feedstock upstream, inside, or downstream of the feed preparation unit. If desired, the alcohol-containing side stream can be processed to provide an alcohol-rich stream or a purified alcohol stream to be combined with the alcohol feedstock.

[0038] In one embodiment, the internal supply stream purification unit includes a solids / hydrocarbon removal unit, followed by an effluent treatment tower. The aqueous stream recovered as bottom distillate from the effluent treatment tower can be divided into an exhaust stream and an aqueous supply stream.

[0039] In other embodiments, the internal supply stream purification unit includes an effluent treatment tower followed by a solids / hydrocarbon removal unit. The aqueous stream recovered as bottom distillate from the effluent treatment tower can be divided into an exhaust stream and an aqueous supply stream, wherein the aqueous supply stream is further processed in the solids / hydrocarbon removal unit.

[0040] In another embodiment, the internal supply stream purification unit includes solids / hydrocarbon removal units located both upstream and downstream of the effluent treatment tower. Aqueous effluent from the upstream solids / hydrocarbon removal unit can be fed into the effluent treatment tower. Subsequently, the aqueous stream recovered as bottom distillate from the effluent treatment tower can be divided into a discharge stream and an aqueous supply stream, wherein the aqueous supply stream is further processed in the downstream solids / hydrocarbon removal unit.

[0041] As described above, the resulting aqueous product stream generated within the internal purification unit can be used as an internal supply stream for various unit operations within one, two, or all of the feed preparation unit, dehydration unit, and product purification unit. In some embodiments, a portion of the aqueous product stream can be used as a diluent to dilute the alcohol feedstock upstream of the feed preparation unit. In some embodiments, a portion of the aqueous product stream can be fed to a steam generation unit for vaporization, or vaporization and superheating, and used as a mixed (steam plus organic matter) dilution steam stream combined with the vaporized alcohol feedstock upstream of the dehydration unit. In some embodiments, a portion of the aqueous product stream can be used as a quenching medium or as an aqueous feed component for an alkaline washing unit. Therefore, the volume of the recovered aqueous product stream, compared to the aqueous discharge stream, can depend on the total anticipated demand for the aqueous product stream used for the various applications described above.

[0042] The vaporization of the aqueous product stream can be carried out, for example, in a boiler, heat exchanger, electric heater, or heating coils installed in the convection or radiation section of a furnace. The superheating of the resulting mixed steam stream can be carried out in a similar unit.

[0043] In some embodiments, since the aqueous product stream may contain entrained solids or other contaminants, the mixed dilution vapor stream can be generated in two heating stages, including an initial heating stage to generate a wet (partially vaporized) vapor stream. The wet vapor stream can then be sprayed or otherwise treated to separate water droplets from the vapor, which may contain entrained solids. The resulting vaporized mixture can then be superheated at its dew point to form a superheated mixed dilution vapor stream. The effluent may include water, solids, and some organic matter, and can then be cooled and combined with the effluent for further processing and treatment before disposing of excess water. In some embodiments, the hot effluent can be used as a heat exchange medium, such as a feed / effluent exchanger, to preheat, for example, the aqueous product stream before vaporization, the aqueous effluent from a quench tower upstream of the effluent treatment tower, or both.

[0044] As described above, the bottom distillate recovered from the effluent treatment tower comprises water, solids, and hydrocarbons. In some embodiments, the bottom distillate recovered from the effluent treatment tower may have a suspended solids content in the range of, for example, about 500 to about 5000 mg / L and a chemical oxygen demand (COD) in the range of about 500 to about 5000 mg / L. Separating solids and hydrocarbons from the bottom distillate in a solids / hydrocarbon removal unit can produce an aqueous product stream having a suspended solids content in the range of about 5 to about 200 mg / L and a COD in the range of about 5 to about 200 mg / L. Using a solids / hydrocarbon removal unit upstream of the effluent treatment tower or both upstream and downstream of the effluent treatment tower can provide different results (higher solids and COD are expected only when removing upstream, and lower solids and COD are expected when removing both upstream and downstream).

[0045] The treated water with an acceptable COD produced by the embodiments described herein can be used for a variety of purposes, both inside and outside a system for producing olefins. For example, the treated water can be used as one or more of the following: cooling water makeup stream, process water makeup stream, utility steam makeup stream, farm irrigation water stream, wastewater discharge stream, or drinking water stream.

[0046] In addition to collecting and using process-generated water (water from alcohol dehydration) as an influent source, embodiments of this document further consider using utility effluent as an influent source. For example, one or more heat exchangers in a system for producing olefins such as ethylene may require steam heaters, such as distillation column reboilers or feed preheaters, feed heaters, or feed superheaters. Condensate streams recovered from these various unit operations can be collected and used as water supply streams, such as cooling water makeup streams, process water makeup streams, utility water makeup streams, wash water streams, or as dilution water streams. In some embodiments, the condensate can be mixed and volatilized with a superheated alcohol stream (superheated ethanol stream) to form a vapor-alcohol mixture (vapor-ethanol mixture).

[0047] In some embodiments, the condensate or treated water may be used as a dilution stream mixed with the alcohol feedstock upstream of the desalination bed. In other embodiments, the condensate or treated water may be used as a process water makeup stream, fed as one or more of a quench water makeup stream or a wash water makeup stream.

[0048] Any excess water generated and not used as an intake water supply or other supplementary flow may be discharged from the system as a wastewater discharge flow.

[0049] Now for reference Figure 1The diagram illustrates a simplified flow chart of a process according to an embodiment of this document. An alcohol feed stream 10, such as a bioethanol feed, is fed into a feed preparation unit 12. If necessary, the alcohol feed stream is diluted with an aqueous stream 14. Although not shown, the feed preparation unit 12 may include various operations, including filtration, desalination, and vaporization of the alcohol feedstock.

[0050] The resulting alcohol feedstock 15 is then mixed with superheated steam 16 to form a mixed alcohol-steam feed stream 18 fed into the dehydration unit 20. In the dehydration unit 20, the alcohol is contacted with a dehydration catalyst and dehydrated to form water and olefins, as well as other reaction byproducts, some of which may be lighter than the olefins (lower boiling points), some of which may be heavier than the olefins (higher boiling points), and many of which are soluble in water. The resulting reaction effluent 22 is recovered from the dehydration unit, and the effluent is cooled and separated in the product purification unit 24. An aqueous stream 26 can be provided as a quenching medium; the quenching process produces a crude olefin stream 28 and an aqueous effluent stream 30. The crude olefin stream can then be further purified to recover the desired olefins.

[0051] The aqueous effluent 30 is then divided into a discharge stream 34 and an internal water supply stream 36. The internal water supply stream is fed into the internal supply stream purification unit 32. The internal supply stream purification unit 32 separates at least a portion of the solids and at least a portion of the organic compounds from the water, producing one or more aqueous product streams for use in the method. As shown, the first (liquid) aqueous product stream 38 can be used to supply the dilution stream 14 to the feed preparation unit 12 and the quenching medium 26 to the product purification unit 24. The second aqueous product stream 40 can be fed into the steam generation unit 42 to generate superheated steam 16, which serves as a heat source and diluent for the dehydration unit 20; the mixed alcohol-steam feed stream 18 can be further superheated in or before the dehydration unit 20. Excess aqueous effluent supplied to the internal supply stream purification unit 32 can be recovered as a second discharge stream 34a. The steam generation process can also produce emissions, which are recovered as effluent stream 34b, and can be combined with effluent streams 34 and 34a and fed together as effluent 44 to a downstream water treatment unit (not shown). Although three internal water-containing supply streams (14, 26, 40) are illustrated, embodiments herein may use only one or two of these internal streams; for example, dilution of alcohol feedstock 10 may not be necessary.

[0052] Now for reference Figure 2A simplified process flow diagram of a system for producing olefins according to embodiments herein is illustrated. Those skilled in the art will understand that pumps, valves, heat exchangers, reboilers, overhead condensers, and other components used in this method are not shown in the simplified process flow diagram. A vaporized alcohol feedstock 50 and a superheated steam stream 52 are fed to a dehydration reactor 54, where the alcohol is converted to olefins and water; if desired or necessary, the alcohol, steam, or a mixture thereof may be further superheated prior to introduction into the dehydration reactor 54. The gaseous dehydration reaction effluent 56 is then fed to a quenching unit 58, where it is contacted with and quenched by a quenching medium 60 to separate a significant amount of water (dilution steam and product water) from the olefins. The crude olefin stream is recovered from the quenching unit 58 as overhead distillate 62, and the aqueous effluent 64 is recovered from the quenching unit 58 as bottom distillate. The crude olefin stream 62 (not shown) may then be further processed to recover the purified olefin product.

[0053] The aqueous effluent 64 is then fed to the effluent treatment tower 70 to separate volatile hydrocarbons from the water. Optionally, the aqueous effluent 64 is fed to the solids / hydrocarbon removal unit 66 to remove any solids and a portion of the hydrocarbons from the aqueous effluent before feeding the resulting partially clarified aqueous effluent 68 to the effluent treatment tower 70.

[0054] In effluent treatment column 70, aqueous effluents (64, 68) are separated to remove volatile hydrocarbons from the water, primarily byproducts of the dehydration reaction. The volatile hydrocarbons are recovered as overhead distillate 72, and the remaining aqueous fraction (including heavier hydrocarbons and possibly some solids) is recovered as bottom distillate 74. Optionally, an alcohol-rich side stream 76 can also be recovered from effluent treatment column 70 and can be reused as feed in dehydration reactor 54.

[0055] The bottom distillate stream 74 is then separated into an exhaust stream 78 and an internal water supply stream 80. At least a portion of any remaining solids and hydrocarbons can be removed from the internal water supply stream 80, resulting in a water-containing supply stream 84. The water-containing supply stream 84 is then fed to a dilution steam tank 86, converting at least a portion of the water-containing supply stream into steam 88, and recovering the remaining unvaporized water-containing supply stream as an exhaust stream 90. The steam 88 can then be superheated in a furnace 92 to produce superheated steam 52, which is supplied to the dehydration reactor 54.

[0056] Figure 3The illustration shows a possible process configuration for generating superheated steam according to embodiments of this document, where similar numbers denote similar components. A water-containing supply stream 84 can be converted into superheated steam in two heating stages. The water-containing supply stream 84 can be fed into a steam tank 86. In the initial heating stage, the water-containing effluent 84a is removed from the steam tank 86 and pumped via a thermosiphon or fed through a heating coil 94 within a furnace 92 to generate a wet (partially vaporized) steam stream 88a. The wet steam stream 88a can then be injected into an internal chamber within the steam tank 86 to separate water droplets from the steam, which may contain entrained solids. The resulting steam 88 can then be fed into a second heating coil 96 within the furnace 92 to generate a superheated dilution steam stream 52. Emissions, possibly including water, solids, and some organic matter, can then be recovered from the steam tank 86 as an exhaust stream 90. Also as Figure 3 As shown, water or steam can be added to the steam tank 86 via the flow line 98 for startup or replenishment.

[0057] As described above, by removing solids and hydrocarbons from the quenched reaction effluent, the embodiments described herein allow for reduced water usage by using water generated during the dehydration reaction to internally supply steam, dilution water, and / or quench water. Improved filtered vaporized water contaminated with alcohols and other oxygenates further becomes an ideal co-feed for diluting anhydrous alcohol feed and can also improve ion exchange feed pretreatment. Additionally, water contaminated with alcohols and other oxygenates can be used for steam generation, with or without hydrocarbon removal.

[0058] Unless otherwise defined, all technical and scientific terms used shall have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, devices, methods, processes and compositions pertain.

[0059] Unless the context clearly indicates otherwise, the singular forms “a”, “an”, and “the” contain plural indicators.

[0060] As used herein and in the appended claims, the words “comprising,” “having,” and “including,” and all their grammatical variations, are each intended to have an open, non-limiting meaning and do not exclude additional elements or steps.

[0061] "Optional" means that the event or situation described below may or may not occur. The description includes both scenarios in which the event or situation occurs and scenarios in which the event or situation does not occur.

[0062] When the terms “approximately” or “about” are used, the term may indicate a value that varies by up to ±10%, up to 5%, up to 2%, up to 1%, up to 0.5%, up to 0.1%, or up to 0.01%.

[0063] A range can be expressed as from about one particular value to about another particular value, including endpoints. When expressing such a range, it should be understood that another embodiment is from one particular value to another particular value, as well as all particular values ​​within the range and combinations thereof.

[0064] While this disclosure includes a limited number of embodiments, those skilled in the art who benefit from it will understand that other embodiments can be devised without departing from the scope of this disclosure. Therefore, the scope should be limited only by the appended claims.

Claims

1. A method for producing ethylene, comprising: The vapor-ethanol mixture is fed into the dehydration reactor; Ethanol is dehydrated in the dehydration reactor to form a reaction effluent containing ethylene and water; The reaction effluent is quenched and separated using a quenching medium containing water to recover the quenched effluent and the gaseous stream containing the ethylene. The quenched effluent is separated to form a volatile organic effluent and an aqueous organic effluent; Removal of solids, hydrocarbons, or both from the quenched effluent, the aqueous organic effluent, or both; and One or both of the following: A portion of the aqueous organic effluent is fed as the quenching medium used in the quenching and separation steps; and A portion of the aqueous organic effluent, including water and hydrocarbon compounds, is vaporized to form a mixed dilution vapor stream and residual liquid, and the vaporized ethanol-containing feedstock is diluted with the mixed dilution vapor stream to form the vapor-ethanol mixture.

2. The method of claim 1, wherein the ethanol is bioethanol, and wherein the method is certified as a green ethylene method.

3. The method according to claim 1 or claim 2, further comprising feeding the residual liquid and the remainder of the aqueous organic effluent into a water treatment unit to produce treated water.

4. The method of claim 3, further comprising using the treated water as one or more of a cooling water makeup stream, a process water makeup stream, a utility steam makeup stream, a farm irrigation water stream, a wastewater discharge stream, or a drinking water stream.

5. The method according to claim 3, further comprising using the treated water as a process water replenishment stream, wherein the process water replenishment stream is one or more of a quench water replenishment stream, a wash water replenishment stream, or a desalination bed dilution water stream being fed.

6. The method according to any one of claims 1 to 5, wherein separating the quenched effluent comprises distilling the quenched effluent to recover a volatile organic stream containing hydrocarbons, including oxygenated hydrocarbons, and recovering a side stream containing unreacted ethanol.

7. The method according to any one of claims 1 to 6, further comprising superheating the mixed dilution vapor stream before mixing it with the vaporized ethanol feedstock.

8. The method according to any one of claims 1 to 7, further comprising contacting the reaction effluent with an alkaline agent or an amine agent to separate acidic gas from the reaction effluent.

9. The method according to any one of claims 1 to 8, further comprising recovering condensate streams from one or more heat exchangers used in the method for producing ethylene, and feeding the condensate streams as one or more of a cooling water makeup stream, a process water makeup stream, a utility steam makeup stream, or as a dilution water stream.

10. The method of claim 9, further comprising mixing the condensate stream with the superheated ethanol stream.

11. A method for producing olefins, comprising: The steam-alcohol mixture is fed into the dehydration reactor; The alcohol is dehydrated in the dehydration reactor to form a reaction effluent containing olefins and water; The reaction effluent is quenched and separated using a quenching medium containing water to recover the quenched effluent and the gaseous hydrocarbons containing the olefin. The quenched effluent is separated to form a volatile organic effluent and an aqueous organic effluent; Removal of solids, hydrocarbons, or both from the quenched effluent, the aqueous organic effluent, or both; and One or both of the following: A portion of the aqueous organic effluent is fed as the quenching medium used in the quenching and separation steps; A portion of the aqueous organic effluent, including water and hydrocarbon compounds, is vaporized to form a mixed dilution vapor stream and residual liquid, and the vaporized oxygenated hydrocarbon feedstock is diluted with the mixed dilution vapor stream to form a steam-oxygenated hydrocarbon mixture.

12. The method of claim 11, wherein the alcohol comprises an alcohol selected from the group consisting of or a mixture of two or more alcohols: ethanol, propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, 3-pentanol, isopentanol, 1-hexanol, 2-hexanol, 3-hexanol, isohexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, and isoheptanol.

13. The method of claim 11, wherein the alcohol comprises ethanol or a mixture of ethanol and one or more alcohols selected from the group consisting of: propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, 3-pentanol, isopentanol, 1-hexanol, 2-hexanol, 3-hexanol, isohexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, and isoheptanol.

14. The method according to any one of claims 11 to 13, wherein the reaction effluent comprises the olefin, water, and one or more reaction byproducts selected from the group consisting of: C1-C8 alkanes, ketones, aldehydes, ethers, methanol, alcohols, acetates, oligomers of the olefin, and aromatics.

15. The method according to any one of claims 11 to 14, wherein the quenched effluent comprises water, light hydrocarbons, unreacted alcohols, dissolved oxygenated hydrocarbon byproducts, and suspended solids.

16. The method according to any one of claims 11 to 15, wherein the gaseous hydrocarbon comprises the olefin and at least a portion of the hydrocarbon-containing byproducts generated in the dehydration reactor.

17. The method of claim 16, further comprising separating the olefin from the hydrocarbon-containing byproduct in the gaseous hydrocarbon to recover a purified olefin product stream.

18. The method according to any one of claims 11 to 17, wherein the volatile organic stream comprises one or more of light hydrocarbons and oxygenated hydrocarbons.

19. The method according to any one of claims 11 to 18, wherein the aqueous organic effluent comprises water, dissolved hydrocarbons, and suspended solids.

20. The method according to any one of claims 11 to 19, further comprising feeding the residual liquid and the remainder of the aqueous organic effluent into a water treatment unit.

21. The method according to any one of claims 11 to 20, further comprising superheating the mixed dilution vapor stream prior to mixing with the vaporized oxygenated hydrocarbon feedstock.

22. The method according to any one of claims 11 to 21, further comprising contacting the reaction effluent with an alkaline agent or an amine agent to adsorb acidic gases from the reaction effluent.

23. The method according to any one of claims 11 to 22, wherein the aqueous organic effluent has a suspended solids content in the range of about 500 to about 5000 mg / L and a chemical oxygen demand (COD) in the range of about 500 to about 5000 mg / L, and wherein, Following the step of removing solids and hydrocarbons from the aqueous organic effluent, the resulting aqueous product stream has a suspended solids content in the range of about 5 to about 200 mg / L and a COD in the range of about 5 to about 200 mg / L.

24. A system for producing filtered water from green ethylene process reaction water containing oxygenated hydrocarbons, ethanol, light hydrocarbons, and suspended solids, the system comprising: A flash evaporation or distillation stage is used to remove light hydrocarbons from the green ethylene reaction water to produce a water-rich stream. The secondary treatment stage includes filters, membranes, or coalescers to remove at least some suspended solids or dirt or heavy oxygenated matter from at least a portion of the rich water flow to produce an aqueous product flow. During the internal supply stage, the aqueous product stream is vaporized and the resulting vaporized aqueous product stream is fed to the dehydration reactor. The aqueous product stream is water vapor with a chemical oxygen demand (COD) of 5 to 200 mg / L and a suspended solids content of 5 to 200 mg / L.

25. A system for producing green ethylene, the system comprising: The feed preparation unit is used to process and vaporize ethanol feedstock to produce vaporized ethanol. A dehydration unit for receiving the vaporized ethanol and superheated vapor mixture, and containing a catalyst for dehydrating the alcohol to form a reaction effluent comprising ethylene, water and reaction byproducts; The product purification unit is configured to quench and separate the reaction effluent to form a crude ethylene product stream containing ethylene and a first portion of the reaction byproducts, and an aqueous effluent stream containing water and the remaining portion of the reaction byproducts. An internal supply stream generating unit is configured to receive the aqueous effluent and remove a second portion of the reaction byproducts to generate an aqueous product stream containing water and the remaining reaction byproducts. An internal supply system is used to vaporize at least a portion of the aqueous product stream and feed it as the superheated steam mixture to the dehydration unit.

26. The system of claim 25, wherein the internal supply system further comprises a feed line for feeding at least a portion of the aqueous product stream to the product purification unit.

27. The system of claim 25 or claim 26, wherein the internal supply system further comprises a feed line for feeding at least a portion of the aqueous product stream to the feed preparation unit.

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