Hydrocarbon purification using caustic cleaning solution

Abstract

Embodiments of this disclosure relate to hydrocarbon purification, specifically the purification of waste plastics using a caustic cleaning solution.

Description

[[Technical Field]]

[0001] Embodiments of the present disclosure are directed to hydrocarbon refining, specifically hydrocarbon refining that utilizes a caustic wash solution. [[Background Art]]

[0002] Waste plastics are often landfilled or incinerated, with only a small proportion diverted to recycling. Recycling of waste plastics can be achieved through various processes in which plastic waste is converted into solid, liquid, and / or gaseous fuels.

[0003] The hydrocarbon stream obtained during waste plastic processing can contain a number of impurities. These impurities may poison catalysts and / or damage other unit operations associated with waste plastic processing. As a result, it may be desirable to remove impurities from hydrocarbons before they are utilized in downstream processes. [[Summary of the Invention]]

[0004] The present disclosure includes, but is not limited to, Various embodiments are provided, including a method for hydrocarbon refining utilizing a caustic wash solution, the method comprising: transferring waste plastic to a depolymerization reactor; depolymerizing the waste plastic in the depolymerization reactor to provide a depolymerization reactor output; transferring the depolymerization reactor output to an extraction column having a caustic wash input; washing the depolymerization reactor output in the extraction column to provide an extraction column raffinate; transferring the extraction column raffinate to a hydroprocessing reactor; and hydroprocessing the extraction column raffinate in the hydroprocessing reactor to provide a purified hydrocarbon. [[Brief Description of the Drawings]]

[0005] [Figure 1] FIG. 1 is a schematic diagram of a hydrocarbon refining system utilizing a caustic wash solution according to an embodiment of the present disclosure. [Figure 2] This is a schematic diagram of a system utilizing a caustic cleaning solution according to an embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a hydrocarbon purification system utilizing a caustic cleaning solution according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0006] This disclosure relates to methods and systems for the purification of waste plastics, such as hydrocarbons, and more specifically, to methods and systems for the purification of waste plastics utilizing a caustic cleaning solution. One or more embodiments provide that waste plastics, such as hydrocarbon streams, are obtained during waste plastic processing. One or more embodiments provide that the waste plastics are solid, for example, before entering a depolymerization reactor.

[0007] Impurities in waste plastics, such as hydrocarbon streams made from plastic waste, can be removed using various technologies. One of the technologies conventionally used to remove impurities from hydrocarbons before vapor decomposition is hydrogenation. In hydrogenation, hydrocarbons are catalytically treated at high temperatures in a hydrogen atmosphere to reduce impurities.

[0008] Plastic waste containing useful hydrocarbons that may be obtained by processing plastic waste may also contain several impurities, such as N, S, Cl, Br, F, Si, P, and / or I. In one or more embodiments, these several impurities may also include one or more metals. For example, waste plastics may contain impurities containing heteroatoms, such as chlorinated compounds, such as those found in polyvinyl chloride, sulfonated compounds, such as t-butylmethyl sulfide, dimethyl disulfide, dibenzothiophene, and / or nitrogen compounds, such as quinoline, which can be converted to acids, such as hydrochloric acid and sulfuric acid, and from nitrogen compounds to ammonia. Catalysts used in hydrogenation may be deactivated more quickly in the presence of higher concentrations of impurities. These impurities may form undesirable compounds such as NH3 and / or HCl, as described above, which may lead to corrosion. Furthermore, HCl may react with NH3 to form NH4Cl, which may lead to blockage of downstream lines and / or contamination of heat exchangers. To mitigate these problems, conventional hydrogenation processes have utilized large amounts of water, for example, to reduce HBr and / or NH3 in hydrocarbons.

[0009] Hydrogenation plants are designed to operate at moderate pressure levels and are not designed to withstand large amounts of catalyst impurities, such as catalyst poisons. Therefore, it is desirable to remove catalyst poisons from waste plastics in the treatment plant.

[0010] Embodiments of this disclosure provide a method for reducing the concentration of impurities in waste plastics, such as hydrocarbons, using a caustic cleaning solution. Advantageously, the embodiments provide that the caustic cleaning solution can replace and / or reduce the water consumption that would otherwise be incurred in hydrocarbon purification. As disclosed herein, the caustic cleaning solution can reduce the concentration of one or more of several components from hydrocarbon streams, such as HCl, HF, HBr, and H2S.

[0011] Figure 1 is a schematic diagram of a hydrocarbon purification system 100 utilizing a caustic cleaning solution according to an embodiment of the present disclosure. As discussed herein, hydrocarbon purification may include depolymerization. The hydrocarbon purification system 100 can be used to purify hydrocarbon materials such as waste plastics. As used herein, “waste plastics” includes raw materials as defined by ISO 18604, polymers recovered from used materials as defined by ISO 14021, and combinations thereof. Waste plastics may include paraffins, oxygenated materials, nitrogenated materials, chlorides, sulfur components, and combinations thereof. Waste plastics may contain large amounts of dienes and olefins, as well as impurities such as N, O, S, and Cl.

[0012] The hydrocarbon purification system 100 may include a depolymerization section 101. The depolymerization section 101 can reduce the size of a polymer, for example, by depolymerizing it. Embodiments provide that the depolymerization section 101 may include one or more known elements, such as a pump, or other known processing elements not shown in Figure 1. The depolymerization section 101 may include a depolymerization reactor. The depolymerization reactor may also be referred to as a hydrogenation depolymerization reactor and / or a catalytic depolymerization reactor. The depolymerization reactor may be a fixed-bed reactor. The depolymerization reactor may include a depolymerization catalyst.

[0013] The depolymerization catalyst may be a supported catalyst containing a group VIII metal selected from the group formed by Ni, Pd, Pt, Co, Rh, Fe, Mo, W, Ti, Cr, V, Zr, and / or Ru, and optionally a group VIB metal selected from the group formed by Mo and / or W, on an amorphous mineral support selected from the group formed by alumina, silica, silica-alumina, magnesia, clay, and combinations thereof. The depolymerization catalyst may also include supported zeolites, such as SiO2, Al2O3, AlPO4, and combinations thereof.

[0014] Depolymerization reactors can operate at temperatures between 50 and 250°C. This includes all individual values ​​and subranges within the 50-250°C range; for example, a depolymerization reactor can operate at temperatures from a lower limit of 50, 60, or 70°C to an upper limit of 250, 240, or 230°C.

[0015] Depolymerization reactors can operate at pressures of 15 to 200 absolute bar (bara). This includes all individual values ​​and subranges within the 15 to 200 bara range; for example, a depolymerization reactor can operate at pressures from a lower limit of 15, 20, or 25 bara to an upper limit of 200, 190, or 180 bara. The combination of pressure and reactor outlet temperature can ensure that a portion of the contents of the depolymerization reactor remain in a liquid state.

[0016] The depolymerization section 101 may have a first input 111. The first input may include waste plastics, for example, unrefined hydrocarbons containing one or more impurities as discussed herein. The first input may include waste plastics in a solid state, for example, pelletized or shredded waste plastics. In other words, embodiments have provided that the first input 111 is not a liquid.

[0017] The first input 111, for example, waste plastics, can have a variety of compositions. The first input 111 can include waste plastics obtained from, for example, bottle caps and closures, milk, water or orange juice containers, detergent bottles, office automation equipment (printers, computers, photocopiers, etc.), white goods (refrigerators, washing machines, etc.), household appliances (televisions, video cassette recorders, stereos, etc.), automobile shredder dust (a mixed material remaining after most of the metal has been separated from shredded automobiles and other metal-rich products "shredded" by metal recyclers), packaging waste, household waste, rotomolded parts (kayaks / coolers), construction waste, and industrial molded and extruded product scrap.

[0018] Examples of waste plastics include polyolefins, such as polyethylene and polypropylene; polyesters, such as poly(ethylene terephthalate); vinyl polymers, such as poly(vinyl chloride); acrylonitrile, butadiene and styrene homopolymers and interpolymers; polyesters, such as poly(ethylene terephthalate) and poly(bisphenol-A carbonate); polyamides, such as nylon 66; polycarbonates, such as poly(bisphenol-A carbonate); acrylics, such as poly(methyl methacrylate); fluorocarbon polymers; polyethers; polysaccharides; silicones, such as poly(dimethylsiloxane); thermoplastic elastomers, such as ethylene-propylene rubber; and combinations thereof.

[0019] In one or more embodiments, the waste plastic is 0.900 to 0.990 g / cm³. 3 It can have a density of 0.900~0.9990 g / cm³. 3 All individual values ​​and subranges are disclosed and incorporated herein, for example, waste plastics are 0.900, 0.905, or 0.910 g / cm³. 3 From the lower limit, 0.990, 0.980, or 0.970 g / cm³ 3 It may have a density up to the upper limit. The density can be measured according to ASTM D792.

[0020] In one or more embodiments, waste plastics may have a melt index (I2) of 0.30 dg / min to 6.00 dg / min. All individual values ​​and subranges of 0.30 dg / min to 6.00 dg / min are disclosed and incorporated herein, for example, waste plastics may have a melt index (I2) from a lower limit of 0.30, 0.80, 1.00, 1.25, 1.50, or 1.80 dg / min to an upper limit of 6.00, 5.00, 4.00, 3.50, 3.00, or 2.80 dg / min. I2 can be measured according to ASTM D1238 (190°C, 2.16 kg).

[0021] The depolymerization section 101 may have a second input 116. The second input may comprise hydrogen. Hydrogen from the second input may react with one or more impurities in the unpurified hydrocarbon from the first input 111 in the presence of a depolymerization catalyst.

[0022] Hydrogen in the depolymerization reactor may have a partial pressure of 10 to 140 bar in the gas phase. All individual values and subranges from 10 to 140 bar are included; for example, hydrogen may have a partial pressure from a lower limit of 10, 12, or 14 bar to an upper limit of 140, 135, or 130 bar.

[0023] The hydrocarbon purification system 100 may include an extraction section 105. The extraction section 105 may include an extraction column. Embodiments provide that the extraction section 105 may include one or more known elements, such as a pump, or other known processing elements not shown in Figure 1. Depolymerization contents from the depolymerization section 101 may be input to the extraction section 105 via a depolymerization output 112. In other words, the output of the depolymerization reactor may be transferred to the extraction column. As used herein, when fluid is transferred from a first component to a second component, the two components are in "fluid communication" with each other.

[0024] The hydrocarbon purification system 100, for example the extraction column, may include a caustic wash liquid input 110 to the extraction section 105. As used herein, "caustic wash liquid" refers to a liquid phase composition having a pH of 8 to 14. All individual values and subranges from 8 to 14 are included; for example, the caustic wash liquid may have a pH from a lower limit of 8, 8.5, or 9 to an upper limit of 14, 13, 12, 11, or 10. The pH of the caustic wash liquid can be measured by known methods, for example, ASTM D1067. The caustic wash liquid may be used for extraction, for example, for washing the depolymerization reactor output in the extraction column.

[0025] One or more embodiments provide that the caustic cleaning solution is a solution. One or more embodiments provide that the caustic cleaning solution is an aqueous solution. One or more embodiments provide that the caustic cleaning solution can be prepared using a base, for example, an alkali. One or more embodiments provide that the caustic cleaning solution can be prepared using sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), or a combination thereof. One or more embodiments provide that the caustic cleaning solution is prepared with NaOH. The caustic cleaning solution input 110 can partially extract heteroatoms, for example, hydrocarbons bonded to chlorine and / or silicon, as well as generated inorganic substances such as H2S, HCl, HF, and HBr.

[0026] The caustic washing input 110 can be 20 to 150 wt% of the total weight of the depolymerized contents from the depolymerization section that are input to the extraction section, for example, the depolymerization reactor output (depolymerized contents from the depolymerization reactor) that are transferred to the extraction column. All individual values ​​and subranges of 20 to 150 are included, for example, the caustic washing can range from a lower limit of 20, 25, or 30 wt% of the total weight of the depolymerized contents from the depolymerization section that are input to the extraction section to an upper limit of 150, 130, or 110 wt%.

[0027] In one or more embodiments, it is provided that the flow rate of the caustic washing solution to the extraction column can be controlled by utilizing an internal recycle flow.

[0028] The extraction column can operate at temperatures of 150–300°C. This includes all individual values ​​and subranges within the 150–300°C range; for example, the extraction column can operate at temperatures from a lower limit of 150, 160, or 170°C to an upper limit of 300, 280, or 260°C.

[0029] The extraction column can operate at pressures of 15–200 bara. This includes all individual values ​​and subranges within the 15–200 bara range; for example, the extraction column can operate at pressures from a lower limit of 15, 20, or 25 bara to an upper limit of 200, 195, or 190 bara.

[0030] The hydrocarbon purification system 100 may include a first extraction section output 119. The recovered material from the extraction column of the extraction section 105 can be sent to the depolymerization section 101 and / or heat transfer section 103 via the first extraction section output 119.

[0031] The hydrocarbon purification system 100 may include a first splitting line 113. A portion of the recovered material from the output 119 of the first extraction section, for example, a portion of the liquid, can be sent to the depolymerization section 101 via the first splitting line 113. Different portions of the recovered material from the output 119 of the first extraction section can be sent to the depolymerization section 101 for various applications. One or more embodiments provide that, based on the total weight % of the recovered material in the output 119 of the first extraction section, 5 to 75 weight percent of the recovered material from the output 119 of the first extraction section can be sent to the depolymerization section. All individual values ​​and partial ranges of 5 to 75 weight percent are included, for example, based on the total weight % of the recovered material in the output 119 of the first extraction section, portions from a lower limit of 5, 10, or 20 weight percent of the recovered material from the output 119 of the first extraction section to an upper limit of 75, 65, or 50 weight percent of the recovered material from the output 119 of the first extraction section can be sent to the depolymerization section.

[0032] The hydrocarbon purification system 100 may include a second splitting line 114. A portion of the recovered material from the first extraction section output 119 can be sent to the heat transfer section 103 via the second splitting line 114. Different portions of the 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, based on the total weight percentage of the recovered material in the first extraction section output 119, 25% to 95% by weight of the recovered material from the first extraction section output 119 can be sent to the transfer section 103. All individual values ​​and sub-ranges of 25 to 95% by weight are included, for example, based on the total weight percentage of the recovered material from the first extraction section output, portions from a lower limit of 25, 35, or 50% by weight of the recovered material from the first extraction section output 119 to an upper limit of 95, 90, or 80% by weight of the recovered material from the first extraction section output can be sent to the heat transfer section 103.

[0033] The hydrocarbon purification system 100 may include a second extraction section output 102. The recovered material from the extraction column of the extraction section 105 can be transferred to the heat transfer section 103 via the second extraction section output 102. The second extraction section output 102 may be used instead of and / or in conjunction with the second splitting line 114. In other words, the total weight % of the recovered material transferred from the extraction section 105 to the heat transfer section 103 can be transferred via the second splitting line 114, the second extraction section output 102, or a combination thereof.

[0034] The hydrocarbon purification system 100 may include a third extraction section output 120. The third extraction section output 120 may be a hydrocarbon-rich output 120. For example, a separator such as the one shown in Figure 2 can be used to separate hydrocarbons and water from the extraction column output to provide a hydrocarbon-rich output 120. The third extraction section output 120 can be removed from the hydrocarbon purification system 100.

[0035] The heat transfer section 103 may include a heat exchanger. Embodiments provide that the heat transfer section 103 may include one or more known elements, such as a pump or other known processing elements not shown in Figure 1. The heat exchanger can operate at temperatures between 250 and 350°C, for example, to bring the material being fed into the heat exchanger to a desired temperature. All individual values ​​and subranges of 250 to 350°C are included, and for example, the heat exchanger can operate at temperatures from a lower limit of 30, 35, or 40°C to an upper limit of 100, 90, or 80°C.

[0036] Heat exchangers can operate at pressures of 15 to 200 bara. This includes all individual values ​​and subranges within the 15 to 200 bara range; for example, a heat exchanger can operate at pressures from a lower limit of 15, 20, or 30 bara to an upper limit of 200, 190, or 180 bara.

[0037] The heat transfer section 103 may include a hydrogen input 107. The hydrogen from the input 107 may have a partial pressure of 15 to 200 bara. This includes all individual values ​​and subranges within 15 to 200 bara; for example, the hydrogen from the input 107 may have a partial pressure ranging from a lower limit of 15, 20, or 25 bara to an upper limit of 200, 190, or 180 bara, with the hydrogen from the input 107 having a higher pressure than the heat exchanger in the heat transfer section 103.

[0038] The heat transfer section 103 may include an output 106. The contents of the heat transfer section 103 can be transferred to the hydrogenation section 104 via the output 106.

[0039] The embodiments provide that the hydrogenation section 104 may include one or more known elements, such as a pump, or other known treatment elements not shown in Figure 1. The hydrogenation section 104 may include a hydrogenation reactor. The hydrogenation reactor may be a fixed-bed reactor. The hydrogenation reactor may include a hydrogenation catalyst.

[0040] The hydrogenation catalyst may be a supported catalyst containing a group VIII metal selected from the group formed by Ni, Pd, Pt, Co, Rh and / or Ru, and optionally a group VIB metal selected from the group formed by Mo and / or W, on an amorphous mineral support selected from the group formed by alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof.

[0041] Hydrogenation reactors can operate at temperatures of 250–350°C. This includes all individual values ​​and subranges within 250–350°C; for example, a hydrogenation reactor can operate at temperatures from the lower limit of 250, 260, or 270°C to the upper limit of 350, 340, or 330°C. One or more embodiments provide that a hydrogenation reactor operates at a higher temperature than that at which a depolymerization reactor operates.

[0042] Hydrogenation reactors can operate at pressures of 15–200 bara. This includes all individual values ​​and subranges within the 15–200 bara range; for example, a hydrogenation reactor can operate at pressures from a lower limit of 15, 20, or 25 bara to an upper limit of 200, 190, or 180 bara.

[0043] Hydrogen in a hydrogenation reactor can have a partial pressure of 10 to 140 bar in the gas phase. This includes all individual values ​​and subranges within the 10 to 140 bar range; for example, hydrogen can have a partial pressure from a lower limit of 10, 15, or 20 bar to an upper limit of 140, 130, or 120 bar. One or more embodiments provide that the partial pressure of hydrogen in a hydrogenation reactor may be lower than that of hydrogen in a depolymerization reactor.

[0044] The hydrogenation section 104 may include an output 108. The hydrogenated contents of the hydrogenation section 104, for example, the hydrogenated material, can be transferred from the hydrogenation section 104 to a downstream process, for example, a stream cracker, via the output 108. The output 108 may be a purified hydrocarbon stream. One or more embodiments provide that the purified hydrocarbon stream includes saturated hydrocarbons, for example, paraffins. As an example, the purified hydrocarbon stream may be C2-C 25 It may contain saturated hydrocarbons.

[0045] Figure 2 is a schematic diagram of a system utilizing a caustic cleaning solution according to an embodiment of the present disclosure. Figure 2 provides a more detailed view of the extraction section 105 shown in Figure 1.

[0046] As discussed in Figure 1, the depolymerized contents from the depolymerization 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 heat transfer unit 250 can cause the contents of output 112 to enter the extraction column 252 at a temperature of 150 to 300°C. This includes all individual values ​​and subranges of 150 to 300°C; for example, the heat transfer unit 250 can cause the contents of output 112 to enter the extraction column 252 at a temperature ranging from a lower limit of 150, 160, or 170°C to an upper limit of 300, 280, or 260°C.

[0047] In one or more embodiments, the heat transfer unit 250 may be optional, and for example, the contents of output 112 may be at a temperature of 150 to 400°C from an upstream process not shown in Figure 2.

[0048] The contents of output 112, which can be heated by the heat transfer unit 250, can be transferred to the extraction column 252. One or more embodiments provide that the contents of output 112 can be transferred to the lower section of the extraction column 252. The extraction column 252 can be used for liquid-liquid extraction. The extraction column 252 can include different known configurations for various applications. The extraction is sometimes called "reactive extraction" because the caustic washing solution can react with one or more impurities in the extraction column.

[0049] As shown in Figure 2, the caustic cleaning solution input 110 can be transferred to the extraction column 252. One or more embodiments provide that the contents of the caustic cleaning solution input 110 can be transferred to the upper section of the extraction column 252. Several processing components can be used to transfer the heat associated with the caustic cleaning solution input 110. Some processing components can be used to provide that the temperature of the caustic cleaning solution input 110 is between 150 and 300°C when it enters the extraction column 252. This includes all individual values ​​and subranges of 150 to 300°C, for example, a heater 250 can provide that the temperature of the caustic cleaning solution input 110 is between a lower limit of 150, 160, or 170°C and an upper limit of 300, 280, or 260°C when it enters the extraction column 252.

[0050] As shown in Figure 2, heat can be transferred to the caustic cleaning solution input 110 using the heat transfer unit 254. The water-rich extraction column output 256 can be used, for example, within the heat transfer unit 254 to transfer heat to the caustic cleaning solution input 110. The water-rich extraction column output 256 can be discharged, for example, from the bottom of the extraction column 252 by gravity.

[0051] As shown in Figure 2, after leaving the heat transfer unit 254, the water-rich extraction column output 256 can be transferred to the heat transfer unit 258. The water-rich extraction column output 256 leaving the heat transfer unit 254 can be at a temperature of 30 to 85°C. This includes all individual values ​​and subranges within the 30 to 85°C range; for example, the water-rich extraction column output leaving the heat transfer unit can be at a temperature from a lower limit of 30, 35, or 40°C to an upper limit of 85, 75, or 65°C.

[0052] The heat transfer unit 258 can provide that the water-rich extraction column output 256 can be at a temperature of 15 to 65°C. This includes all individual values ​​and subranges within the 15 to 65°C range. For example, the heat transfer unit 258 can provide that the water-rich extraction column output is at a temperature ranging from a lower limit of 15, 20, or 25°C to an upper limit of 65, 55, or 45°C.

[0053] The water-rich extraction column output 256 can be sent from the heat transfer unit 258 to the separator 260. The separator 260 can be used to separate hydrocarbons and water from the water-rich extraction column output 256. The separator 260 can include different known configurations for various applications.

[0054] 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 the extraction section 105.

[0055] The water-rich separator output 262 can be transferred to the pump 264. As shown in Figure 2, the caustic washing input 110 may include a first portion of the water-rich separator output 262, while a second portion of the water-rich separator output 262 can be removed from the extraction section 105 by output 266, for example, to avoid excessive accumulation of undesirable components. One or more embodiments provide that the pump 264 can be used to recirculate the water-rich separator output 262, which may help reduce the intake of supplemental caustic solution. One or more embodiments provide that the recirculation of the first portion of the water-rich separator output 262 may allow the mass ratio of recycled water to hydrocarbons to be maintained at approximately 1:1.

[0056] As shown in Figure 2, the extraction section 105 may include an extraction column roughenate 268. The extraction column roughenate 268 may be hydrogen-rich. The extraction column roughenate 268 can be produced by washing the depolymerization reactor output in the extraction column. As will be discussed further herein, the extraction column roughenate 268 may be transferred to a hydrogenation reactor to provide a purified hydrocarbon stream by hydrogenation treatment.

[0057] Extraction column roughenate 268 may contain hydrocarbons. Extraction column roughenate 268 may contain 60% to 100% by weight of hydrocarbons, based on the total weight of hydrocarbons and water in the extraction column roughenate 268. This includes all individual values ​​and subranges of 60% to 100% by weight, for example, the extraction column roughenate may contain hydrocarbons from a lower limit of 60, 65, or 70% by weight to an upper limit of 100, 95, or 90% by weight, based on the total weight of hydrocarbons and water in the extraction column roughenate. Water in extraction column roughenate 268 may be harmful to one or more downstream catalysts.

[0058] The extraction column roughenate 268 can have temperatures of 100 to 185°C. This includes all individual values ​​and subranges of 150 to 300°C, for example, the extraction column roughenate 268 can have temperatures from a lower limit of 150, 160, or 170°C to an upper limit of 300, 280, or 260°C.

[0059] The extraction column roughenate 268 can be transferred to the heat transfer unit 270. One or more embodiments provide that the extraction column roughenate 268 entering the heat transfer unit 270 has a higher temperature than the caustic cleaning solution input 110 entering the heat transfer unit 270. In other words, heat can be transferred from the extraction column roughenate 268 to the caustic cleaning solution input 110.

[0060] The extraction column roughenate 268 can be transferred from the heat transfer unit 270 to the heat transfer unit 272. The heat transfer unit 272 can be used to precisely control the temperature of the extraction column roughenate 268 entering the three-phase separator 274. The extraction column roughenate 268 entering the three-phase separator 274 can have different temperatures for various applications.

[0061] The three-phase separator 274 can have a temperature range of 25 to 100°C. This includes all individual values ​​and subranges within the 25 to 100°C range; for example, the three-phase separator can have a temperature range from a lower limit of 25, 30, or 35°C to an upper limit of 100, 90, or 80°C. The three-phase separator 274 can have a pressure that maintains at least 60% by weight of the water in the three-phase separator in a liquid state.

[0062] The three-phase separator 274 can be used 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 may contain spent caustic alkali.

[0063] Preferably, the hydrocarbon stream 280 can provide reduced poisoning of the catalyst compared to hydrocarbon streams prepared by other processes. Therefore, the hydrocarbon stream 280 can be advantageously utilized for further downstream processing.

[0064] Figure 3 is a schematic diagram of a hydrocarbon purification system 300 utilizing a caustic cleaning solution according to an embodiment of the present disclosure. Figure 3 provides a more detailed view of the hydrocarbon purification system 100 shown in Figure 1.

[0065] As discussed in Figure 1, a first input 111 containing waste plastics, for example, unrefined hydrocarbons, can be used. The first input may include waste plastics that are in solid phase.

[0066] The first input 111 can be transferred to the heat transfer unit 330. The heat transfer unit 330 can provide the first input 111 to be at a temperature of 150 to 400°C. This includes all individual values ​​and subranges of 150 to 400°C. For example, the heat transfer unit 330 can provide the first input 111 to be at a temperature from a lower limit of 150, 160, or 170°C to an upper limit of 400, 380, or 360°C.

[0067] From the heat transfer unit 330, the first input 111 can be transferred to the depolymerization reactor 332, for example, unrefined hydrocarbons can be transferred to the depolymerization reactor 332. In other words, the depolymerization reactor 332 can be in fluid communication with an upstream process that provides the waste plastic flow to the depolymerization reactor 332, for example, a conveyor. The depolymerization reactor 332 may be part of the depolymerization section 101, as discussed in Figure 1. Embodiments provide that within the depolymerization reactor 332, the waste plastic of the first input 111 is depolymerized, for example, the waste plastic is broken down into relatively small polymer segments.

[0068] As discussed herein, the output from the depolymerization reactor 332 can be transferred to the extraction section 105. Embodiments of the present disclosure provide, as described above, the use of a caustic cleaning solution to reduce the concentration of impurities in hydrocarbons, such as the output from the depolymerization reactor 332. As disclosed herein, the caustic cleaning solution can reduce the concentration of one or more of several components from the hydrocarbon stream, such as HCl, HF, HBr, and H2S.

[0069] As shown in Figure 2, several flows, including a hydrogen flow 276, an aqueous flow 278, and a hydrocarbon flow 280, can be output from the extraction section 105.

[0070] As shown in Figure 3, the aqueous stream 278 can be removed from the hydrocarbon purification system 300. The hydrogen stream 276 can be recycled within the hydrocarbon purification system 300. The hydrocarbon stream 280, containing the hydrocarbons purified using the caustic washing solution of the extraction section 105, can be used for further downstream hydrogenation treatments utilizing a catalyst, which is deactivated more quickly in the presence of relatively high concentrations of impurities. Because the hydrocarbon stream 280 contains purified hydrocarbons, i.e., because the hydrocarbon stream 280 has a relatively low concentration of impurities compared to hydrocarbon streams provided by other processes, the downstream hydrogenation catalyst remains active longer than a hydrogenation catalyst exposed to a hydrocarbon stream with relatively high concentrations of impurities. One or more embodiments provide that the purified hydrocarbon stream 280 contains saturated hydrocarbons, such as paraffins. A variety of saturated hydrocarbons can be obtained for different applications.

[0071] As shown in Figure 3, the hydrocarbon flow 280 can be transferred via pump 342 to several heat transfer units, for example, heat transfer unit 334, heat transfer unit 336, and heat transfer unit 338, on its way to the hydrogenation reactor 340 of the hydrogenation section 104 discussed in Figure 1. Although three heat transfer units 334, 336, and 338 are shown on the way to the hydrogenation reactor 340, embodiments are not limited in this way. For example, various embodiments provide that there may be fewer than three or more heat transfer units on the way to the hydrogenation reactor 340.

[0072] Hydrocarbons hydrogenated in the hydrogenation reactor 340 can be transferred to a flash unit 344, for example, a flash drum. As shown in Figure 3, the hydrocarbons hydrogenated in the hydrogenation reactor 340 may pass through several heat transfer units, for example, heat transfer units 336 and 342, on their way to the flash unit 344. Although two heat transfer units 336 and 342 are shown on the way to the flash unit 344, the embodiments are not limited in this way. For example, various embodiments provide that there may be fewer than two or more heat transfer units on the way to the flash unit 344.

[0073] The flash unit 344 can be used to provide a gas phase flow 346 and a liquid phase flow 348. The liquid phase flow 348 may be called the final product of the hydrocarbon purification system 300. The liquid phase flow 348 contains hydrocarbons, e.g., aromatics and / or C5-C5 12 May contain paraffin within this range.

[0074] The gas phase flow 346 may include hydrogen, relatively light hydrocarbons (compared to the liquid phase flow 348), and / or inorganic by-products of the hydrogenation process, such as H2S, NH3, and HCl.

[0075] The gas phase flow 346 can be transferred to a scrubber 350. The scrubber 350 may utilize an aqueous NaOH flow 352 to process the gas phase flow 346. The used NaOH from the scrubber 350 can be recovered via the scrubber output 350. The scrubbed gas can be recycled to the hydrocarbon purification system 300 via a scrubbed gas recycling flow 356 through a compressor 358. As shown in Figure 3, the scrubbed gas recycling flow 356 can be combined with a hydrogen input flow 360, for example, before the compressor 358.

[0076] A portion of the scrubbed gas from scrubber 350 can be purged from the hydrocarbon purification system 300 by a scrubbed gas purge stream 362. Different amounts of the scrubbed gas from scrubber 350 can be purged for various applications.

Claims

1. A method for purifying hydrocarbons using a caustic cleaning solution, Transferring waste plastics to a depolymerization reactor, The waste plastic is depolymerized in the depolymerization reactor to provide the output of the depolymerization reactor, The output of the depolymerization reactor is transferred to an extraction column having a caustic washing solution input, A method comprising washing the depolymerization reactor output with the caustic washing solution input within the extraction column to provide an extraction column raffinate.

2. Transferring the extraction column raffinate to a hydrogenation reactor, The method according to claim 1, further comprising hydrogenating the extraction column raffinate in the hydrogenation reactor to provide a purified hydrocarbon stream.

3. The method according to claim 1, wherein the caustic cleaning solution is a liquid phase composition having a pH of 8 to 14.

4. The method according to claim 1, wherein the caustic cleaning solution is an aqueous solution.

5. The method according to claim 1, wherein the caustic cleaning solution contains sodium hydroxide.

6. The method according to claim 1, wherein the caustic washing solution is 20 to 150 percent by weight of the total weight of the depolymerized contents from the depolymerization reactor that is input to the extraction column.

7. The method according to claim 1, wherein the extraction column operates at a temperature of 100 to 300°C and a pressure of 15 to 200 absolute bars.

8. A depolymerization reactor, An extraction column that is in fluid communication with the depolymerization reactor, wherein the extraction column includes a caustic washing solution input, A hydrocarbon purification system comprising a hydrogenation reactor in fluid communication with the extraction column.

9. The system according to claim 8, wherein the depolymerization reactor is in fluid communication with an upstream process that supplies a waste plastic flow to the depolymerization reactor.

10. The system according to claim 8, wherein the hydrogenation reactor hydrogenates the extracted column raffinate to provide a purified hydrocarbon stream.

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