Hydrocarbon purification utilizing a caustic wash

Abstract

Embodiments of the present disclosure are directed towards hydrocarbon purification and specifically plastic pyrolysis oil purification utilizing a caustic wash.

Description

HYDROCARBON PURIFICATION UTILIZING A CAUSTIC WASHField of Disclosure

[0001] Embodiments of the present disclosure are directed towards hydrocarbon purification and specifically plastic pyrolysis oil purification utilizing a caustic wash.Background

[0002] Waste plastics have often been diverted to landfills or are incinerated, with a smaller fraction being diverted to recycling. Recycling of waste plastics can occur through a pyrolytic process in which the plastic waste is converted into solid, liquid, and / or gaseous fuels. For example, pyrolysis of waste plastics can produce products like naphtha, ethylene, propylene, and aromatic compounds, among other compounds.

[0003] The pyrolysis process is a thermochemical degradation reaction at high temperatures that decomposes plastic waste. Pyrolysis gasoline can be produced by a non-catalytic steam-cracking process. Both pyrolysis oil and pyrolysis gasoline are highly unsaturated streams, as they are produced at high temperature and low pressure. Pyrolysis oil contains a relatively greater amount of impurities than pyrolysis gasoline. These impurities have the potential to poison catalysts and / or damage the pyrolysis gasoline hydrogenation plant in the case of co-processing pyrolysis oil. As a result, it can be desirable to remove impurities from the hydrocarbon before the hydrocarbon is utilized in downstream processes.Summary

[0004] The present disclosure provides various embodiments, including without limitation:

[0005] A method for hydrocarbon purification utilizing a caustic wash, the method including: transferring non-purified hydrocarbons to a 'first hydrogenation reactor; hydrotreating the non-purified hydrocarbons in the first hydrogenation reactor to provide a first hydrogenation reactor output; transferring the first hydrogenation reactor output to an extraction column having a caustic wash input; washing the first hydrogenation reactor output in the extraction column to provide an extraction column raffinate; transferring the extraction column raffinate to a second hydrogenation reactor; hydrotreating the extraction column raffinate in the second hydrogenation reactor to provide a purified hydrocarbon.Brief Description of Drawings

[0006] Figure 1 is a schematic diagram of a hydrocarbon purification system utilizing a caustic wash according to an embodiment of the present disclosure.

[0007] Figure 2 is a schematic diagram of a pyrolysis system utilizing a caustic wash according to an embodiment of the present disclosure.

[0008] Figure 3 is a schematic diagram of a hydrocarbon purification system utilizing a caustic wash according to an embodiment of the present disclosure.Detailed Description

[0009] The present disclosure is directed toward methods and systems for hydrocarbon purification and specifically plastic pyrolysis oil purification utilizing a caustic wash.

[0010] Impurities in hydrocarbons, e.g., pyrolysis oil made from plastic waste, can be removed using a variety of techniques. One technique that has been previously utilized to remove the impurities from hydrocarbons prior to steam cracking is hydroprocessing. In hydroprocessing, hydrocarbons are catalytically processed under an atmosphere of hydrogen at elevated temperatures to help reduce the impurities.

[0011] Pyrolysis oil derived from a plastic waste and other sources including useful hydrocarbons, can also include a number of impurities, such as N, S, Cl, Br, F, Si, P, and / or I. One or more embodiments provide that the number of impurities can also comprise one or more metals. As an example, waste plastics can include impurities including heteroatoms such as chlorinated compounds, e.g., as found in polyvinyl chloride, sulfonated compounds, e.g., t-butylmethylsulfide, dimethyldisulfide, dibenzothiophene, etc, and / or nitrogen compounds, e.g., quinoline, that can be converted into acids, e.g., hydrochloric acid, sulfuric acid, and ammonia from the nitrogen compounds. Catalysts utilized for hydroprocessing can be deactivated sooner when a higher concentration of impurities is present. These impurities, as mentioned, can form undesirable compounds such as NH3and / or HCI, which may lead to corrosion. Additionally, HCI may react with NH3to form NH4CI, which may lead to plugging downstream lines and / or fouling of heat exchangers. To mitigate these issues, previous hydroprocessing processes have utilized large amounts of water, e.g., to reduce HBr and / or NH3in the hydrocarbons.

[0012] Pretreating pyrolysis oil with an aqueous solution of sodium hydroxide can be effective at high temperatures such as 250 °C, however the presence of conjugated dienes in the untreated oil can lead to fouling at this temperature, especially in the presence of water. Pyrolysis gasoline hydrogenation plants are designed to run at moderate pressure levels and are not designed to tolerate high amounts of catalystimpurities, e.g., poisons. Therefore, removal of poisons is desirable to co-process pyrolysis oil in pyrolysis gasoline plants.

[0013] Embodiments of the present disclosure provide that a caustic wash is utilized to reduce an impurity concentration in hydrocarbons. Embodiments provide that, advantageously, the fouling formation of conjugated dienes in the caustic wash scrubber can be mitigated. Embodiments provide that, advantageously, the caustic wash can replace and / or reduce water consumption from hydrocarbon purification. The caustic wash, as disclosed herein, can reduce one or more concentrations of a number of components from a hydrocarbon stream, such as, HCI, HF, HBr, and H2S, for instance.

[0014] Figure 1 is a schematic diagram of a hydrocarbon purification system 100 utilizing a caustic wash according to an embodiment of the present disclosure. The hydrocarbon purification system 100 can be utilized to purify a hydrocarbon material, such as pyrolysis gasoline. As used herein, “pyrolysis oil” refers to material obtained from pyrolyzed waste plastics. As used herein, “pyrolysis gasoline” refers to a C5-C12 material obtained from a steam cracking process. Pyrolysis gasoline may include aromatics, olefins, dienes, cyclic dienes, cyclic diolefins, paraffins, oxygenates, nitrogenates, chlorides, sulfur components, and combinations thereof. Pyrolysis oil and pyrolysis gasoline may each respectively include large amounts of dienes and olefins, as well as impurities, such as N, O, S, and Cl, for example.

[0015] The hydrocarbon purification system 100 can include a first hydrogenation section 101. Embodiments provide that the first hydrogenation section 101 may include one or more known elements, e.g., a pump, or other known processing elements, not shown in Figure 1. The first hydrogenation section 101 can include a first hydrogenation reactor. The first hydrogenation reactor can be a fixed bed reactor. The first hydrogenation reactor can include a first hydrogenation catalyst.

[0016] The first hydrogenation catalyst can be supported catalyst comprising a group VIII metal chosen from the group formed by Ni, Pd, Pt, Co, Rh and / or Ru, optionally a group VIB metal chosen from the group Mo and / or W, on an amorphous mineral support chosen from the group formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof.

[0017] The first hydrogenation reactor can operate at a temperature from 50 to 250 °C. All individual values and subranges from 50 to 250 °C are included; for example, the first hydrogenation reactor can operate at a temperature from a lower limit of 50, 60, or 70 to an upper limit of 250, 240, or 230 °C.

[0018] The first hydrogenation reactor can operate at a pressure from 15 to 200 bar absolute (bara). All individual values and subranges from 15 to 200 bara are included; for example, the first hydrogenation reactor can operate at a pressure from a lower limit of 15, 20, or 25 to an upper limit of 200, 190, or 180 bara. The combination of pressure and reactor outlet temperature can provide that the majority, e.g., greater than 60 mass % or more, of water remains in the liquid phase in the downstream extraction column.

[0019] The first hydrogenation section 101 can have a first input 111. The first input can comprise non-purified hydrocarbons, e.g., hydrocarbons including one more impurities as discussed herein. The first input can comprise a pyrolysis gasoline made from an upstream pyrolysis process not shown in Figure 1. In other words, the nonpurified hydrocarbons can be pyrolysis gasoline. The first input can comprise nonpurified hydrocarbons in a liquid state. The non-purified hydrocarbons can be a pyrolyzed plastics oil stream mixed with pyrolysis gasoline.

[0020] The first hydrogenation section 101 can have a second input 116. The second input can comprise hydrogen. The hydrogen from the second input can react, in the presence of the hydrogenation catalyst, with one or more impurities of the nonpurified hydrocarbons from the first input.

[0021] The hydrogen in the first hydrogenation reactor can have a partial pressure, in the vapor phase, from 10 to 140 bar. All individual values and subranges from 10 to 140 bar are included; for example, the hydrogen can have a partial pressure from a lower limit of 10, 12, or 14 to an upper limit of 140, 135, or 130 bar.

[0022] The hydrocarbon purification system 100 can include an extraction section 105. The extraction section 105 can include an extraction column. Embodiments provide that the extraction section 105 may include one or more known elements, e.g., a pump, or other known processing elements, not shown in Figure 1. Hydrotreated contents from the first hydrogenation section 101 can be input to the extraction section 105 by output 112. In other words, a first hydrogenation reactor output can be transferred to the extraction column. As used herein, two components are in “fluid communication” with one another when fluid is transferred from a first of the components to a second of the components.

[0023] The hydrocarbon purification system 100, e.g., the extraction column, can include a caustic wash input 110 to extraction section 105. As used herein, “caustic wash” refers to a liquid phase composition having a pH from 8 to 12. All individual valuesand subranges from 8 to 12 are included; for example, the caustic wash can have a pH from a lower limit of 8, 8.5, or 9 to an upper limit of 12, 11 , or 10. The pH of the caustic wash can be determined by a known method, e.g., ASTM D1067. The caustic wash can be utilized for extraction, e.g., washing the first hydrogenation reactor output in the extraction column.

[0024] One or more embodiments provide that the caustic wash is a solution. One or more embodiments provide that the caustic wash is an aqueous solution. One or more embodiments provide that the caustic wash can be prepared with a base, e.g., an alkali. One or more embodiments provide that the caustic wash can be prepared with sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), or combinations thereof. One or more embodiments provide that the caustic wash is prepared with NaOH. The caustic wash input 110 can partially extract hydrocarbons bonded to heteroatoms, e.g., chlorine and / or silicon, as well as produced inorganics such as H2S, HCI, HF and HBr.

[0025] The caustic wash input 110 can be from 20 to 150 weight percent (wt %), of a total weight of hydrotreated contents from the first hydrogenation section that are input to the extraction section, e.g., the first hydrogenation reactor output (hydrotreated contents from the first hydrogenation reactor) that is transferred to the extraction column. All individual values and subranges from 20 to 150 are included; for example, the caustic wash can be from a lower limit of 20, 25, or 30 wt% to an upper limit of 150, 130, or 110 wt% of the total weight of hydrotreated contents from the first hydrogenation section that are input to the extraction section.

[0026] One or more embodiments provide that internal recycle streams may be utilized to control the caustic wash flow rate into the extraction column.

[0027] The extraction column can operate at a temperature from 100 to 250 °C. All individual values and subranges from 100 to 250 °C are included; for example, the extraction column can operate at a temperature from a lower limit of 100, 110, or 120 to an upper limit of 250, 240, or 230 °C.

[0028] The extraction column can operate at a pressure from 15 to 200 bara. All individual values and subranges from 15 to 200 bara are included; for example, the extraction column can operate at a pressure from a lower limit of 15, 20, or 25 to an upper limit of 200, 195, or 190 bara.

[0029] The hydrocarbon purification system 100 can include a first extraction section output 119. Recovered material from the extraction column of exaction section105 can be sent via the first extraction section output 119 to the first hydrogenation section 101 and / or a heat transfer section 103.

[0030] The hydrocarbon purification system 100 can include the first split line113. A portion of recovered material, e.g., liquid, from the first extraction section output 119 can be sent to the hydrogenation section 101 via the first split line 113. Different portions of recovered material from the first extraction section output 119 can be sent to the hydrogenation section 101 for various applications. One or more embodiments provide that from 5 weight percent (wt%) to 75 wt% of recovered material from the first extraction section output 119 can be sent to the first hydrogenation section based upon a total wt% of recovered material in the first extraction section output 119. All individual values and subranges from 5 to 75 wt% are included; for example, from a lower limit of 5, 10, or 20 wt% to an upper limit of 75, 65, or 50 wt% of recovered material from the first extraction section output 119 can be sent to the first hydrogenation section based upon the total wt% of recovered material in the first extraction section output 119.

[0031] The hydrocarbon purification system 100 can include a second split line114. A portion of recovered material from the first extraction section output 119 can be sent to a heat transfer section 103 via the second split line 114. Different portions of recovered material from the first extraction section output 119 can be sent to the heat transfer section 103 for various applications. One or more embodiments provide that from 25 wt% to 95 wt% of recovered material from the first extraction section output 119 can be sent to the heat transfer section 103 based upon a total wt% of recovered material in the from the first extraction section output 119. All individual values and subranges from 25 to 95 wt% are included; for example, from a lower limit of 25, 35, or 50 wt% to an upper limit of 95, 90, or 80 wt% of recovered material from the first extraction section output 119 can be sent to the heat transfer section 103 based upon the total wt% of recovered material from the first extraction section output.

[0032] The hydrocarbon purification system 100 can include a second extraction section output 102. Recovered material from the extraction column of exaction section 105 can be sent via the second extraction section output 102 to the heat transfer section 103. The second extraction section output 102 may be utilized in place of and / or in conjunction with a second split line 114. In other words, the total wt% of recovered material transferred from the extraction section 105 to the heat transfer section 103 can be transferred via the second split line 114, the second extraction section output 102, or a combination thereof.

[0033] The hydrocarbon purification system 100 can include a third extraction section output 120. The third extraction section output 120 can be a hydrocarbon-rich output 120. For example, a separator, e.g., as shown in Figure 2, 104 can be utilized to separate hydrocarbons and water from an extraction column output to provide the hydrocarbon-rich output 120. The third extraction section output 120 can be removed from the hydrocarbon purification system 100.

[0034] The heat transfer section 103 can include a heat exchanger.Embodiments provide that the heat transfer section 103 may include one or more known elements, e.g., a pump, or other known processing elements, not shown in Figure 1. The heat exchanger can operate at, e.g., materials sent to the heat exchanger can brought to a desired temperature, a temperature from 250 to 350 °C. All individual values and subranges from 250 to 350 °C are included; for example, the heat exchanger can operate at an inlet temperature from a lower limit of 30, 35, or 40 to an upper limit of 100, 90, or 80 °C.

[0035] The heat exchanger can operate at a pressure from 15 to 200 bara. All individual values and subranges from 15 to 200 bara are included; for example, the heat exchanger can operate at a pressure from a lower limit of 15, 20, or 30 to an upper limit of 200, 190, or 180 bara.

[0036] The heat transfer section 103 can include a hydrogen input 107. The hydrogen from input 107 can have a partial pressure from 15 to 200 bara. All individual values and subranges from 15 to 200 bara are included; for example, the hydrogen from input 107 can have a partial pressure from a lower limit of 15, 20, or 25 to an upper limit of 200, 190, or 180 bara, wherein the hydrogen from input 107 has a pressure greater than the heat exchanger of heat transfer section 103.

[0037] The heat transfer section 103 can include an output 106. The contents of heat transfer section 103 can be transferred to a second hydrogenation section 104 via the output 106.

[0038] As mentioned, the hydrocarbon purification system 100 can include a second hydrogenation section 104. Embodiments provide that the second hydrogenation section 104 may include one or more known elements, e.g., a pump, or other known processing elements, not shown in Figure 1. The second hydrogenation section 104 can include a second hydrogenation reactor. The second hydrogenation reactor can be a fixed bed reactor. The second hydrogenation reactor can include a second hydrogenation catalyst.

[0039] The second hydrogenation catalyst can be supported catalyst comprising a group VIII metal chosen from the group formed by Ni, Pd, Pt, Co, Rh and / or Ru, optionally a group VIB metal chosen from the group Mo and / or W, on an amorphous mineral support chosen from the group formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof.

[0040] The second hydrogenation reactor can operate at a temperature from 250 to 350 °C. All individual values and subranges from 250 to 350 °C are included; for example, the second hydrogenation reactor can operate at a temperature from a lower limit of 250, 260, or 270 to an upper limit of 350, 340, or 330 °C. One or more embodiments provide that the second hydrogenation reactor operates at a temperature that is greater than a temperature that the first hydrogenation reactor operates at. In other words, the second hydrogenation reactor can have a greater operational temperature than the first hydrogenation reactor.

[0041] The second hydrogenation reactor can operate at a pressure from 15 to 200 bara. All individual values and subranges from 15 to 200 bara are included; for example, the second hydrogenation reactor can operate at a pressure from a lower limit of 15, 20, or 25 to an upper limit of 200, 190, or 180 bara.

[0042] The hydrogen in the second hydrogenation reactor can have a partial pressure, in the vapor phase, from 10 to 140 bar. All individual values and subranges from 10 to 140 bar are included; for example, the hydrogen can have a partial pressure from a lower limit of 10, 15, or 20 to an upper limit of 140, 130, or 120 bar. One or more embodiments provide that the hydrogen in the second hydrogenation reactor can have a partial pressure that is less than the hydrogen partial pressure in the first hydrogenation reactor 101.

[0043] The second hydrogenation section 104 can include an output 108. Hydrotreated contents of second hydrogenation section 104 can be transferred out of the second hydrogenation section 104, e.g., to a downstream process such as a stream cracker, via the output 108.

[0044] Figure 2 is a schematic diagram of an extraction section utilizing a caustic wash according to an embodiment of the present disclosure. Figure 2 provides a more detailed view of extraction section 105, shown in Figure 1.

[0045] As discussed with Figure 1 hydrotreated contents from the first hydrogenation section 101 can be input to the extraction section 105 by output 112. As shown in Figure 2, output 112 can be transferred to a heat transfer unit 250. The heattransfer unit 250 can provide that the contents of the output 112 are at a temperature from 100 to 250 °C to enter extraction column 252. All individual values and subranges from 100 to 250 °C are included; for example, the heat transfer unit 250 can provide that the contents of the output 112 are at a temperature from a lower limit of 100, 120, or 140 to an upper limit of 250, 240, or 230 °C to enter extraction column 252.

[0046] One or more embodiments provide that the heat transfer unit 250 can be optional, e.g., the contents of the output 112 can be at a temperature from 50 to 250 °C from an upstream process not shown in Figure 2.

[0047] The contents of the output 112, which can be heated by heat transfer unit 250, can be transferred to extraction column 252. One or more embodiments provide that the contents of the output 112 can be transferred to a lower section of the extraction column 252. The extraction column 252 can be utilized for a liquid-liquid extraction. The extraction column 252 can include different known configurations for various applications. The extraction may be referred to as a “reactive extraction”, as the caustic wash can react with one or more impurities in the extraction column.

[0048] As shown in Figure 2, the caustic wash input 110 can be transferred to extraction column 252. One or more embodiments provide that the contents of the caustic wash input 110 can be transferred to an upper section of the extraction column 252. A number of processing components can be utilized to transfer heat associated with the caustic wash input 110. The number of processing components can be utilized to provide that the caustic wash input 110 is at a temperature from 100 to 250 °C when entering the extraction column 252. All individual values and subranges from 100 to 250 °C are included; for example, the heater 250 can provide that the caustic wash input 110 is a at temperature from a lower limit of 100, 120, or 140 to an upper limit of 250, 240, or 230 °C when entering the extraction column 252.

[0049] As shown in Figure 2, heat transfer unit 254 can be utilized to transfer heat to the caustic wash input 110. A water-rich extraction column output 256 can be utilized to transfer heat, e.g., within the heat transfer unit 254, to the caustic wash input 110. The water-rich extraction column output 256 can be discharged by gravity, for example, at a bottom portion of the extraction column 252.

[0050] As shown in Figure 2, after exiting the heat transfer unit 254, the waterrich extraction column output 256 can be transferred to heat transfer unit 258. The waterrich extraction column output 256 exiting the heat transfer unit 254 can be at a temperature from 30 to 85 °C. All individual values and subranges from 30 to 85 °C areincluded; for example, the water-rich extraction column output exiting the heat transfer unit can be at a temperature from a lower limit of 30, 35, or 40 to an upper limit of 85, 75, or 65 °C.

[0051] The heat transfer unit 258 can provide that the water-rich extraction column output 256 can be at a temperature from 15 to 65 °C. All individual values and subranges from 15 to 65 °C are included; for example, the heat transfer unit 258 can provide that the water-rich extraction column output is at a temperature from a lower limit of 15, 20, or 25 to an upper limit of 65, 55, or 45 °C.

[0052] From the heat transfer unit 258, the water-rich extraction column output 256 can be sent to a separator 260. The separator 260 can be utilized to separate hydrocarbons and water from the water-rich extraction column output 256. The separator 260 can include different known configurations for various applications.

[0053] The separator 260 can provide a hydrocarbon-rich separator output 120 and a water-rich separator output 262. The hydrocarbon-rich separator output 120 can be removed from extraction section 105.

[0054] The water-rich separator output 262 can be transferred to pump 264. As shown in Figure 2, the caustic wash input 110 can comprise a first portion of the waterrich separator output 262, while second portion of the water-rich separator output 262 can be removed, e.g., to avoid over accumulation of undesirable components, from the extraction section 105 by output 266. One or more embodiments provide that pump 264 can be utilized to help diminish the intake of make-up caustic solution via recirculation of the water-rich separator output 262. One or more embodiments provide that the recirculation of the first portion of the water-rich separator output 262 can provide that a recycled water to hydrocarbon mass ratio can be maintained at approximately 1 :1.

[0055] As shown in Figure 2, the extraction section 105 can include an extraction column raffinate 268. The extraction column raffinate 268 can be hydrogen rich. The extraction column raffinate 268 can be produced by washing the first hydrogenation reactor output in the extraction column. As discussed further herein, the extraction column raffinate 268 can be transferred to a second hydrogenation reactor for hydrotreating to provide a purified hydrocarbon stream.

[0056] The extraction column raffinate 268 can comprise hydrocarbons. The extraction column raffinate 268 can be from 60 wt% to 100 wt% hydrocarbons based upon a total weight of hydrocarbons and water in the extraction column raffinate 268. All individual values and subranges from 60 wt% to 100 wt% are included; for example,the extraction column raffinate can be from a lower limit of 60, 65, or 70 wt% to an upper limit of 100, 95, or 90 wt% hydrocarbons based upon a total weight of hydrocarbons and water in the extraction column raffinate. Water, in the extraction column raffinate 268, may be harmful to one or more downstream catalysts.

[0057] The extraction column raffinate 268 can have a temperature from 100 to 250 °C. All individual values and subranges from 100 to 250 °C are included; for example, the extraction column raffinate 268 can have a temperature from a lower limit of 100, 120, or 140 to an upper limit of 250, 240, or 230 °C.

[0058] The extraction column raffinate 268 can be transferred to heat transfer unit 270. One or more embodiments provide that extraction column raffinate 268 entering the heat transfer unit 270 has a temperature greater than the caustic wash input 110 entering the heat transfer unit 270. In other words, heat can be transferred from the extraction column raffinate 268 to the caustic wash input 110.

[0059] From the heat transfer unit 270, the extraction column raffinate 268 can be transferred heat transfer unit 272. Heat transfer unit 272 can be utilized to precisely control a temperature of the extraction column raffinate 268 entering a three-phase separator 274. The extraction column raffinate 268 entering a three-phase separator 274 can have different temperatures for various applications.

[0060] The three-phase separator 274 can have a temperature from 25 to 60 °C. All individual values and subranges from 25 to 60 °C are included; for example, the three-phase separator can have a temperature from a lower limit of 25, 30, or 35 to an upper limit of 60, 55, or 50 °C. The three-phase separator 274 can have a pressure that maintains 60 wt% or more of water in the three-phase separator in a liquid state.

[0061] The three-phase separator 274 can be utilized to separate the extraction column raffinate 268 into a hydrogen stream 276, an aqueous stream 278, and a hydrocarbon stream 280. The aqueous stream 278 can include spent caustic.

[0062] Desirably, the hydrocarbon stream 280 may provide reduced poisoning to catalysts, as compared to hydrocarbon streams prepared by other processes. As such, the hydrocarbon stream 280 can be advantageously utilized for further downstream processing that utilizes.

[0063] Figure 3 is a schematic diagram of a hydrocarbon purification system 300 utilizing a caustic wash according to an embodiment of the present disclosure. Figure 3 provides a more detailed view of hydrocarbon purification system 100, shown in Figure 1.

[0064] As discussed with Figure 1 , the first input 111 comprising non-purified hydrocarbons can be utilized. The first input can comprise a pyrolysis gasoline made from an upstream pyrolysis process (not shown).

[0065] The first input 111 can be transferred to heat transfer unit 330. Heat transfer unit 330 can provide that the first input 111 is at a temperature from 50 to 250 °C. All individual values and subranges from 50 to 250 °C are included; for example, the heat transfer unit 330 can provide that the first input 111 is at a temperature from a lower limit of 50, 55, or 60 to an upper limit of 250, 240, or 230 °C.

[0066] From the heat transfer unit 330, the first input 111 can be transferred to a first hydrogenation reactor 332, e.g., non-purified hydrocarbons can be transferred to a first hydrogenation reactor 332. In other words, the first hydrogenation reactor 332 can be fluid communication with an upstream process that provides a pyrolyzed plastics oil stream to the first hydrogenation reactor 332. The first hydrogenation reactor 332 can be as discussed with Figure 1 , e.g., part of the first hydrogenation section 101.Embodiments provide that within the first hydrogenation reactor 332 conjugated dienes, styrene, and / or a portion of alkenes (linear and / or cyclic) of the first input 111 are hydrogenated. This hydrogenation is an exothermic process, e.g., the non-purified hydrocarbons in the first hydrogenation reactor can be hydrotreated to provide a first hydrogenation reactor output.

[0067] From the first hydrogenation reactor 332, output can be transferred to the extraction section 105, as discussed herein. Embodiments of the present disclosure provide that the caustic wash, as previously mentioned, is utilized to reduce an impurity concentration in hydrocarbons, such as the output from the first hydrogenation reactor 332. The caustic wash, as disclosed herein, can reduce one or more concentrations of a number of components from a hydrocarbon stream, such as, HCI, HF, HBr, and H2S, for instance.

[0068] As shown in Figure 2, a number of streams, including hydrogen stream 276, aqueous stream 278, and hydrocarbon stream 280, can be output from the extraction section 105.

[0069] As shown in Figure 3, the aqueous stream 278 can be removed from the hydrocarbon purification system 300. The hydrogen stream 276 can be recirculated in the hydrocarbon purification system 300. The hydrocarbon stream 280, which comprises hydrocarbons that have been purified utilizing the caustic wash of the extraction section 105, can be used for further downstream hydroprocessing that utilizes catalysts, whichare deactivated sooner when a relatively higher concentration of impurities is present. Because the hydrocarbon stream 280 comprises hydrocarbons that have been purified, i.e. hydrocarbon stream 280 comprises a relatively lower concentration of impurities as compared to hydrocarbon streams provided by other processes, advantageously, downstream hydroprocessing catalysts remain active longer than hydroprocessing catalysts that are exposed to hydrocarbon streams having relatively higher concentrations of impurities.

[0070] As shown in Figure 3, the hydrocarbon stream 280 can be transferred, via pump 342, to a number of heat transfer units, e.g., heat transfer unit 334, heat transfer unit 336, heat transfer unit 338 enroute to a second hydrogenation reactor 340 of the second hydrogenation section 104 discussed with Figure 1. While three heat transfer units 334, 336, 338 are shown the enroute to the second hydrogenation reactor 340, embodiments are not so limited. For instance, various embodiments provide there may be fewer than three or more than three heat transfer units enroute to the second hydrogenation reactor 340.

[0071] Hydrocarbons, which have been hydroprocessed in the second hydrogenation reactor 340 can be transferred to a flash unit 344, e.g., a flash drum. As shown in Figure 3, hydrocarbons, which have been hydroprocessed in the second hydrogenation reactor 340 enroute to the flash unit 344 may pass through a number of heat transfer units, e.g., heat transfer unit 336 and heat transfer unit 342. While two heat transfer units 336, 342 are shown the enroute to the flash unit 344, embodiments are not so limited. For instance, various embodiments provide there may be fewer than two or more than two heat transfer units enroute to the flash unit 344.

[0072] The flash unit 344 can be utilized to provide a gas-phase stream 346 and a liquid-phase stream 348. The liquid-phase stream 348 may be referred to as an end product of the hydrocarbon purification system 300. The liquid-phase stream 348 may comprise hydrocarbons, e.g., aromatics, olefins, and / or paraffins ranging from C5to C12.

[0073] The gas-phase stream 346 may comprise hydrogen, relatively lighter hydrocarbons (as compared to the liquid-phase stream 348), and / or inorganic byproducts of the hydroprocessing, such as H2S, NH3, and HCI.

[0074] The gas-phase stream 346 may be transferred to a scrubber 350. The scrubber 350 may utilize an aqueous NaOH stream 352 for processing the gas-phase stream 346. Spent NaOH from the scrubber 350 can be recovered via scrubber output 350. Scrubbed gas can be recycled, via compressor 358, to the hydrocarbon purificationsystem 300 by scrubbed gas recycle stream 356. As shown in Figure 3, the scrubbed gas recycle stream 356 can be combined with a hydrogen input stream 360, e.g., prior to the compressor 358.

[0075] A portion of scrubbed gas from scrubber 350 may purged from the hydrocarbon purification system 300 by scrubbed gas purge stream 362. Different amounts of scrubbed gas from scrubber 350 may purged for various applications.

Claims

ClaimsWhat is claimed is:1 . A method for hydrocarbon purification utilizing a caustic wash, the method comprising: transferring non-purified hydrocarbons to a first hydrogenation reactor; hydrotreating the non-purified hydrocarbons in the first hydrogenation reactor to provide a first hydrogenation reactor output; transferring the first hydrogenation reactor output to an extraction column having a caustic wash input; washing the first hydrogenation reactor output with the caustic wash input in the extraction column to provide an extraction column raffinate; transferring the extraction column raffinate to a second hydrogenation reactor; hydrotreating the extraction column raffinate in the second hydrogenation reactor to provide a purified hydrocarbon stream.

2. The method of claim 1 , wherein the non-purified hydrocarbons are a pyrolyzed plastics oil stream mixed with pyrolysis gasoline.

3. The method of claim 1 , wherein the caustic wash is a liquid phase composition having a pH from 8 to 12.

4. The method of claim 1 , wherein the caustic wash is an aqueous solution.

5. The method of claim 1 , wherein the caustic wash comprises sodium hydroxide.

6. The method of claim 1 , wherein the caustic wash is from 20 to 150 weight percent of a total weight of hydrotreated contents from the first hydrogenation reactor that are input to the extraction column.

7. The method of claim 1 , where the extraction column operates at a temperature from 100 to 250 °C and a pressure from 15 to 200 bar absolute.

8. A hydrocarbon purification system comprising:a first hydrogenation reactor; an extraction column in fluid communication with the first hydrogenation reactor, wherein the extraction column includes a caustic wash input; and a second hydrogenation reactor in fluid communication with the extraction column.

9. The system of claim 8, wherein the first hydrogenation reactor is in fluid communication with an upstream process that provides a pyrolyzed plastics oil stream to the first hydrogenation reactor.

10. The system of claim 8, wherein the second hydrogenation reactor hydrotreats an extraction column raffinate to provide a purified hydrocarbon stream.

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