Production of hydrocarbon products from aromatic renewable feedstocks

Abstract

A process and process equipment for producing a hydrocarbon product comprising a low content of HPNA from a hydrocarbon-containing stream originating from the thermochemical decomposition of solid renewable material.

Description

Technical Field

[0001] The present invention relates to a method for producing hydrocarbon products from a hydrocarbon stream containing feedstock derived from the thermochemical decomposition of a solid material. Background Technology

[0002] The use of solid materials (e.g., lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers) and liquid streams containing dispersed solids (e.g., sewage sludge) as feedstocks for hydrocarbon production has been explored. These solid materials generate hydrocarbon-containing streams upon thermochemical decomposition, which have been identified as containing compounds that can form high molecular weight heavy polynuclear aromatic hydrocarbons (HPNAs) under hydrocracking conditions. This can lead to catalyst deactivation and equipment fouling, particularly in hydrocracking steps with recirculation configurations. Summary of the Invention

[0003] The paper proposes solutions to this unresolved problem through one or more means, including the use of process steps active in hydrodearomatization and separation steps that selectively remove HPNA precursors and HPNA from the process.

[0004] definition

[0005] From a hydrocracking perspective, unconverted oil (UCO) or unconverted products are materials that boil above the desired, stated, or implied final boiling point. For this purpose, unconverted products from hydrocracking process steps are considered to be products with boiling points above the implied limit, regardless of any chemical transformation from feedstock to product.

[0006] For hydrocracking process steps, the term conversion rate should be based on the mass of the "unconverted" product from the hydrocracking process step (i.e., the mass of the product boiling above the defined limit (m)). UCO The corresponding mass of the high-boiling-point feedstock going to the hydrocracking process step (i.e., the mass of the feedstock boiling above the defined limit (m)). HBF The conversion rate is defined as 1-m. UCO / m HBF And this is usually reported as a percentage. Typically, the fractionation downstream of hydrocracking will define the boiling point limit for the "unconverted products".

[0007] When hydrocracking is carried out in a recycle configuration (where "unconverted" products are separated and recycled to the inlet of the hydrocracking reactor), the conversion can be considered from two perspectives: single-pass conversion and total conversion. Single-pass conversion is based on a local analysis of a single reactor, for which m is considered at both the reactor inlet and outlet. UCO and m HBF The overall conversion rate, considered from the perspective of process steps, is m', which is the amount of water entering the overall process step. HBF(Upstream of the recirculation flow) and m' leaving the total process step UCO (Fractions that boil above the implied limit and are withdrawn from the process, excluding recycle fractions). The total conversion is calculated as 1-m' UCO / m' HBF It is usually reported as a percentage value.

[0008] When referring to boiling point, according to the definition of simulated distillation in ASTM D7500, it can be the initial boiling point or a specific percentage boiling point. The average boiling point should be understood as the volume average boiling point conforming to refining techniques (such as the American Petroleum Institute's Technical Data Book). The initial boiling point (IBP), final boiling point (FBP), and the temperature corresponding to the sample recovery should be interpreted according to these ASTM standards. x T 95 and T 97 The boiling point should be understood accordingly as the distillation temperature at which X wt%, 95 wt%, and 97 wt% were recovered, respectively. x To T y The fraction should be understood as the fraction in T x To T y Similarly, for fractions that boil within a temperature range, T x+ The fraction should be understood as the fraction in T x The above boiling fraction.

[0009] According to the terminology system in this field, the term bubble point should be considered as the temperature at which bubbles first form in a hydrocarbon mixture under a given pressure.

[0010] According to the terminology system in this field, the term stripping tower should be considered as a countercurrent multistage separation device that utilizes an external stripping medium, such as steam or gas, supplied from the bottom of the tower to facilitate the separation of the feed stream into lighter, low-molecular-weight products recovered at the top and heavier, high-molecular-weight products recovered at the bottom. Typically, the temperature of the steam will be lower than that of the feed stream to be separated, and therefore the temperatures of the light and heavy streams leaving the stripping tower will be lower than those of the feed stream.

[0011] According to the terminology of this field, a fractionating column should be considered a countercurrent multistage separation unit used to separate at least two, but typically three or more, product fractions based on boiling range and relative volatility. The degree of separation in the column is determined by the combination of the reflux rate and the number of equilibrium stages employed. External heat is typically applied to the feed stream, the bottom of the column, or the intermediate stream within the column to generate the desired reflux. Fractionating columns may also be additionally fed with a steam stream or other stripping medium to support the separation.

[0012] When expressed in wt% or ppmwt When referring to concentration, this should be understood as weight / weight% or weight / parts per million. For solids and liquids, unless otherwise stated, concentration should be considered on a weight-based basis.

[0013] According to the terminology of this field, a gas / liquid separator should be considered as a container that receives a feed stream consisting of a vapor phase and a liquid phase, provides sufficient volumetric residence time for the phases to separate by gravity, and then removes them from the container as two or more product streams. Typically, separation sections comprising several gas / liquid separators can be configured to separate at different pressure and temperature levels, which can provide more efficient separation and / or higher thermal efficiency. Depending on the water content in the feed stream, the gas / liquid separator can be a two-phase separator or a three-phase separator, and when a specific embodiment describes a three-phase separator associated with the generation or addition of water, such separators can be appropriately considered equivalent to two-phase gas / liquid separators if the amount of water present is low (e.g., below 1 wt%).

[0014] In the following text, the elemental concentrations, such as carbon, hydrogen, oxygen, and nitrogen, should be the total mass of such element relative to the total mass of all molecules in the composition.

[0015] In the following text, hydrocarbon feedstock should be used to refer to feedstock rich in molecules containing hydrogen and carbon, but may also contain heteroatoms, i.e., other elements such as oxygen, sulfur and nitrogen.

[0016] In the following text, hydrocarbons should be used to refer to feedstocks rich in hydrogen and carbon, but may also contain heteroatoms, i.e., other elements such as oxygen, sulfur and nitrogen, in an elemental content of less than 1 wt.

[0017] The H:C atomic ratio should be understood as the ratio between these elements in the elemental analysis of the composition.

[0018] Polynuclear aromatic hydrocarbons (PNAs) should be understood in the following text as hydrocarbon compounds having multiple aromatic rings (e.g., two or more).

[0019] Heavy polynuclear aromatic hydrocarbons (HPNAs) should be understood in the following text as compounds having at least seven aromatic rings. PNAs should be understood to include HPNAs.

[0020] When referring to solid materials, this should also be understood to include dispersed solid materials, such as sewage sludge and manure, of which at least 5% by weight is solid.

[0021] When referring to the concentration of aromatic compounds or other molecular groups, the concentrations should be expressed as the concentrations of all such molecules, not just functional groups.

[0022] The severity of reaction conditions should be understood as the extent to which a given reaction occurs. For example, the severity of hydrodesulfurization should be understood as an increase resulting from changes in one or more physical or chemical conditions that lead to an increase in the extent of hydrodesulfurization.

[0023] When a process step is described as "including" a certain step, this should be understood as including the step as a sub-step.

[0024] The term “includes” should be understood as including in whole or in part, and should not be understood as excluding other steps or materials.

[0025] Technical issues

[0026] Solid renewable feedstocks containing aromatic structures (e.g., lignocellulosic biomass including wood products, forestry waste, and agricultural residues) can be converted into liquid feedstocks through thermochemical decomposition. Liquid feedstocks may contain polycyclic aromatic structures derived from the solid feedstock structure. Similar products can also be observed with certain synthetic aromatic polymers. Typically, hydrocarbon-containing feedstocks derived from the thermochemical decomposition of solid renewable materials contain 50-85 wt% C and 3-50 wt% O, with an atomic ratio between H and C of less than 1.8 or 1.6.

[0027] In one aspect, thermal decomposition is hydrothermal liquefaction. Hydrothermal liquefaction refers to the thermochemical conversion of biomass into liquid fuel by treating it in a hot, pressurized water environment for a sufficient time to break down the solid biopolymer structure into primarily liquid components. Typical hydrothermal treatment conditions are temperatures of 250–425 °C and operating pressures of 40–350 bar. Compared to pyrolysis (e.g., rapid pyrolysis), this technology offers the advantages of operating at lower temperatures, higher energy efficiency, and lower tar yield. Equivalent solvent decomposition methods exist, in which solvents other than water are used.

[0028] In one aspect, pyrolysis also includes passing the solid renewable feedstock through a solid renewable feedstock preparation section, which includes, for example, drying for water removal and / or pulverization for particle size reduction, particularly for processes other than hydrothermal liquefaction using water actively. Any moisture / humidity vaporized in the solid renewable feedstock during, for example, the pyrolysis section will condense in the pyrolysis oil stream and thus be carried away in the process, which may be undesirable. Furthermore, the heat used for water vaporization removes the heat that would otherwise be necessary for pyrolysis. By removing water and providing a smaller particle size in the solid renewable feedstock, the thermal efficiency of the pyrolysis section is increased.

[0029] The products of pyrolysis (referred to as pyrolysis oil) typically require further processing to remove heteroatoms. The physical properties of the pyrolysis oil (e.g., boiling and freezing points) may be satisfactory, making impurity removal the sole requirement. This can be achieved through hydrotreating—adding hydrogen without intending to break carbon-carbon bonds, for example, to remove heteroatoms (e.g., sulfur, oxygen, nitrogen, metals, and halogens) and to saturate olefins. This hydrotreating can advantageously be carried out in the presence of compatible feedstocks (e.g., liquid hydrocarbon streams from fossil or biological sources).

[0030] Catalytically active materials in hydrotreating typically include an active metal (a sulfide base metal, such as nickel, cobalt, tungsten, and / or molybdenum, but if the hydrocarbon does not contain sulfur and nitrogen compounds, it may also include elemental noble metals, such as platinum and / or palladium, and other platinum group metals) and a refractory support (e.g., alumina, silica, or titanium dioxide, or combinations thereof). Hydrotreating conditions typically include temperatures in the range of 250–460 °C, pressures in the range of 3–30 MPa, and a catalytic activity of 0.1–5 hr. -1 Liquid hourly space velocity (LHSV) within the range of 300-10000 Nm 3 / m 3 The GOR (gas-to-oil ratio) is optionally accompanied by intercooling via quenching of the feed or product with cold hydrogen. However, for reactive compounds (e.g., olefins), hydrotreating may occur at temperatures as low as 100°C to 200°C or 250°C, and it may be necessary to perform hydrotreating under such very mild conditions to reduce reactivity in order to control the reaction (e.g., polymerization or thermal overheating). The severity of hydrotreating is generally increased by increasing the temperature, hydrogen availability (partial pressure and relative flow rate), and the metal content and dispersion on the catalyst.

[0031] When the heteroatom products of hydrotreatment are fluids (e.g., hydrocarbons and products containing heteroatoms (e.g., water, ammonia, hydrochloric acid, and hydrogen sulfide)), these products will exit the reactor and be separated downstream. When the heteroatom products are solids (e.g., released metals, silicon, and phosphorus), they typically precipitate onto the catalytically active material; therefore, the catalytically active material is preferably designed to absorb such solid heteroatom compounds, for example, through high porosity, high specific surface area, and high pore size.

[0032] Typically, the molecular structure of pyrolysis oils is modified through hydrocracking. In hydrocracking, carbon-carbon bonds break with the addition of hydrogen, resulting in a reduction in molecular size or the opening of rings.

[0033] Materials exhibiting catalytic activity in hydrocracking typically include active metals (e.g., elemental noble metals such as platinum and / or palladium) or sulfided base metals such as nickel, cobalt, tungsten, and / or molybdenum), acidic supports (typically molecular sieves exhibiting high cracking activity and possessing topologies such as MFI, BEA, and FAU, or amorphous silica-alumina or combinations thereof), and refractory supports (e.g., alumina, silica, or titanium dioxide, or combinations thereof). Materials exhibiting catalytic activity in isomerization are similar, but acidic supports possess different structures, supporting only specific molecular reconstructions, or exhibiting lower acidity, for example, due to the silicon:aluminum ratio, thus making the reaction more specific. Hydrocracking conditions using sulfided catalysts typically include temperatures ranging from 300–460 °C, pressures ranging from 3 MPa to 15 MPa, 20 MPa, or 30 MPa, and 0.5–8 hr. -1 Liquid hourly space velocity (LHSV) within the range of 300-5000 Nm 3 / m 3 The GOR (Gross Orbit) is optionally accompanied by intercooling via quenching of the feed or product with cold hydrogen. Hydrocracking conditions using elemental noble metal catalysts typically include lower temperatures in the range of 230–315 °C, but are otherwise similar. The severity of hydrocracking and isomerization is generally increased by increasing temperature, decreasing space velocity, hydrogen availability (partial pressure and relative flow rate), metal content and dispersion, and the acidity of the molecular sieve and acid support on the catalyst. As is known to those skilled in the art, the severity of hydrocracking can be varied to optimize the process with respect to product composition and boiling point in response to demands from product mix or feedstock characteristics. The selection of catalyst activity can be used to support the required severity flexibility.

[0034] As mentioned above, hydrotreating catalysts can contain noble metals or sulfide base metals. Noble metals (one or both of platinum and palladium—and possibly other platinum group metals—IUPAC Groups 8, 9, and 10, Periods 5 and 6) are active in elemental form and in low concentrations (e.g., 0.05 wt% to 2 wt%). Noble metals are sensitive to the presence of sulfur and nitrogen, in particular, which can significantly reduce activity; therefore, concentrations must be below 50 ppm. wt It operates in the presence of sulfur and nitrogen, which is known as the sweet mode. In contrast, the base metals (typically molybdenum and tungsten, which can be promoted by the presence of nickel and cobalt) are active in their sulfide forms, requiring much higher concentrations (2-20 wt% molybdenum and / or tungsten combined with nickel and / or cobalt in an atomic ratio of 0.2-1.0), and are therefore very robust in the presence of such heteroatoms (known as acid gases), practically requiring concentrations exceeding 50-200 ppm. wtOperating in the presence of sulfur is known as sour mode. Furthermore, the acidity of the support for hydrocracking and isomerization catalysts can be reduced by ammonia, a product of the hydrotreatment of nitrogen-containing hydrocarbons. At moderate levels, such as 50 ppb to 50 ppm, ammonia can be used to control selectivity for middle distillates. At higher levels, the presence of ammonia may be undesirable as it deactivates cracking and isomerization activity.

[0035] While the oxygen-rich structure of renewable materials is not expected to lead to significant amounts of HPNA precursors, it has now been found that the structure of renewable pyrolysis oils may possess properties that lead to the formation of problematic amounts of stable polynuclear aromatic compounds (PNAs). Such compounds are known in the hydrocracking of fossil crude oil, particularly from the process of hydrocracking VGO in a recycling configuration. Quantitative analysis of HPNAs is subject to uncertainty, but problematic amounts of HPNAs typically range from 100 wtppm to 1000 wtppm and above.

[0036] The formation of heavy polynuclear aromatic (HPNA) compounds from polycyclic aromatic hydrocarbons (PNAs) is a known problem in hydrocracking processes. These compounds form as byproducts in undesirable side reactions and are characterized by their stability and resistance to conversion to lighter products. HPNA compounds are polycyclic aromatic compounds with seven or more rings, such as benzene (C). 24 H 12 Benzene halobenzene C 28 H 14 , dibenzo[a]benzene C 32 H 16 and egg benzene C 32 H 14 .

[0037] Problems arise when HPNA compounds exceed their low solubility limits. This can lead to solidification on the surfaces of delivery lines, valves, and heat exchangers, causing operational difficulties. Furthermore, HPNA compounds can deactivate catalysts by inducing irreversible coking at active reaction sites.

[0038] The accumulation of HPNA compounds in the recirculated stream can lead to catalyst deactivation and potential fouling of the equipment, negatively impacting the efficiency and productivity of the hydrocracking process. The conventional solution to this problem is to remove a portion of the recirculated oil stream to remove HPNA compounds, but this has its drawbacks, as it limits the total achievable conversion level in the hydrocracker and requires more unconverted oil removal than anticipated.

[0039] To some extent, PNA and HPNA can be converted to aromatics via hydrodearomatization at moderate temperatures in the presence of hydrogen. This shifts the equilibrium between aromatic and non-aromatic ring structures towards the non-aromatic group. The non-aromatic compound can then be directed to hydrocracking, where ring-opening occurs without forming HPNA. The equilibrium between the aromatic compound and its non-aromatic equivalent favors the non-aromatic equivalent at low temperatures and high pressures. Given the non-reactivity of PNA and HPNA, high equilibrium driving forces are required, such as pressures above 100 bar and temperatures below 350 °C.

[0040] Materials with catalytic activity in hydrodearomatization operate at moderate temperatures and are therefore typically selected to have higher hydrogenation activity than materials with catalytic activity in hydrotreating to compensate for the reduction in activity due to lower temperatures.

[0041] This effect is preferably achieved through a material with catalytic activity in hydrodearomatization, comprising a high content of an active metal, such as a noble metal from at least 0.1 wt%, at least 0.5 wt%, or at least 1 wt% to 3 wt% of Pt or Pd, or a molybdenum or tungsten from at least 1 wt%, at least 5 wt%, or at least 15 wt% to a maximum of 20 wt%, a maximum of 30 wt%, or a maximum of 50 wt% of nickel, promoted by nickel in an amount ranging from 0.1:1 Ni:Mo+W to 2:1 Ni:Mo+W (where the ratio refers to the molar ratio between the amount of Ni and the total amount of Mo and W), supported on a refractory oxide support such as alumina, silica, titanium dioxide, silica-alumina, or molecular sieves. The hydrodearomatization catalyst may also contain only reduced Ni as the active metal on the refractory support, or may be a supportless monolithic catalyst containing at least 50% sulfided Mo and / or W. The degree of hydrodearomatization is increased by increasing the pressure (typically in the range of 10-30 MPa, especially the hydrogen pressure, which is usually above 80% of the total pressure) and by increasing the amount and dispersion of metals on the catalyst. As mentioned earlier, decreasing the temperature will shift the equilibrium towards non-aromatic compounds, but will also reduce the activity of the catalyst.

[0042] In conventional recycle hydrocracking processes, heavy feedstock is combined with hydrogen-rich gas and reacted over a catalyst to produce lower molecular weight products. The liquid products are separated (e.g., by fractionation), and the heavy fraction is recycled to increase conversion to the desired products. To avoid excessive HPNA buildup, a side stream of the heavy fraction is removed from the process, but it is desirable to minimize the amount of non-HPNA in this removed stream to minimize yield loss.

[0043] Because standard analytical methods in this field have been optimized for fossil feedstocks, the concentration and speciation of aromatic compounds in renewable feedstocks become more complex. The presence of high oxygen content, particularly in renewable feedstocks, renders indirect methods inaccurate, leading to the selection of alternative analytical methods. One such example is the use of the H:C atomic ratio as an indicator of aromatic compound content in feedstocks. In fossil VGO (vacuum gas oil), atomic H:C values ​​are typically above 1.6 but below 1.8, indicating increased aromatic content, including higher-order aromatic compounds such as polynuclear aromatics, especially those with four or more rings. In biogenic aromatic pyrolysis oils, also after hydrotreating, this ratio may be even lower, for example, below 1.6, 1.55, or 1.5.

[0044] The activity of hydrotreating catalysts is partly related to their composition, but in addition, catalysts can be temporarily passivated or even permanently deactivated due to the presence of other compounds. One example is that the presence of basic organic nitrogen compounds can passivate catalysts; therefore, to ensure high activity of hydrodearomatic catalysts, deep hydrotreating may be necessary to remove such organic nitrogen compounds.

[0045] Solution to the problem

[0046] The processing of pyrolysis oil containing HPNA precursors can be carried out in many ways.

[0047] In a simple implementation, hydrodearomatization is sufficient, especially if HPNA formation is minimized. This primarily occurs when the HPNA precursor content in the hydrotreated oil is moderate, such as an H:C ratio above 1.6 and below 1.8. In this case, minimizing the nitrogen content (especially basic organic nitrogen) is beneficial to ensure maximum activity of the equilibrium reaction for the catalytic formation of non-aromatic compounds. Depending on product requirements, this can be combined with a hydrocracking step, where C-C bonds are broken, leading to a ring-opening reaction.

[0048] Hydrocrackers are typically operated under conditions that favor converting materials with boiling points above the desired endpoint by 20% or 40% to 75% or 95% (single pass), achieving higher total conversion (e.g., close to 100%) through the recirculation of the high-boiling fraction. Lower total conversion (e.g., 80%, 90%, or 95%) is also relevant, especially if the high-boiling fraction can be used in a value-creating manner.

[0049] In more demanding cases (which is likely more common), the amount of HPNA precursor is higher, as indicated by an H:C ratio below 1.6 (e.g., 1.5 or even 1.4). This necessitates further ring-opening using a hydrocracking catalyst, but also introduces the additional risk of HPNA formation. Similarly, hydrodearomatization upstream of the hydrocracking catalyst is desirable, as this will make the cyclic compounds more reactive and therefore more readily ring-opened, since they will be more reactive than their corresponding aromatic counterparts.

[0050] While the tandem steps of hydrodearomatization and hydrocracking may help avoid HPNA formation and related problems, additional steps may be needed to prevent such issues. One such additional step involves recycling the highest-boiling compounds for hydrocracking. By recycling these compounds around the hydrocracking reactor, a certain amount of high-boiling compounds will be converted into low-boiling compounds, but the presence of HPNA precursors may lead to the formation of additional HPNA. Therefore, a process can be introduced to efficiently separate the HPNA formed from the recycle stream. This process could include a stripping process at elevated temperatures, which drives high-boiling non-HPNA compounds into the gas phase, while the very high-boiling HPNA remains in the liquid phase and can be removed from the process.

[0051] The amount of non-PNA in the sludge stream can be reduced through a high-temperature stripping step. This stripping step can use any stripping medium, but steam is most commonly used. Since steam typically has a lower temperature than the high-boiling fraction, it will be cooled in the stripping column, which can increase the amount of liquid phase removed. The net removal of unconverted oil can be reduced by heating any stream entering the stripping step (including the stripping medium, the unconverted oil to be stripped, any recirculated stream, or equipment involved in the stripping step). This step vaporizes most of the substrate fraction stream, concentrating the HPNA in the heavier bottom liquid, which is then removed from the hydrocracker as a net sludge stream. This process results in higher overall conversion and increased yields of valuable distillate products in the hydrocracker.

[0052] Such stripping steps can be carried out on a high-boiling stream upstream of a fractionating column, allowing most of the HPNA to be transferred from the fractionating column, or on all or part of the bottom stream directed for recirculation. In both cases, a moderately sized stripping column will be able to remove an HPNA-rich sub-stream from the recirculation, thereby reducing the amount of HPNA in the recirculation. When a heated stripping column is located upstream of a fractionating column, the highest-boiling fraction (e.g., fractions boiling above T95 or T97) will not become part of the recirculation stream, as it is diverted to the scavenging stream.

[0053] Implementation schemes that include separating HPNA from the intermediate stream and possibly separating HPNA together with PNA are also relevant. This can be combined with any of the above-mentioned hydrodearomatization and / or hydrocracking processes, particularly with processes that include hydrocracking stream recycling. The separation of HPNA and PNA is preferably carried out in a heated stripping step. Attached Figure Description

[0054] Figure 1 The process for hydrodearomatization and hydrocracking of the entire hydrotreating stream is described.

[0055] Figure 2 This describes a process that involves hydrodearomatizing the entire hydrotreating stream and hydrocracking only the high-boiling-point stream.

[0056] Figure 3 The process of hydrodearomatization and hydrocracking of recycled high-boiling-point streams is described.

[0057] Figure 4 The process describes the hydrodearomatization and hydrocracking of the recycled high-boiling-point stream, as well as the heating stripping upstream of the fractionation.

[0058] Figure 1

[0059] Figure 1 The process layout for producing hydrocarbon product (140) from a hydrocarbon stream (102) is shown. The hydrocarbon stream (102) originates from the thermochemical decomposition of a solid material (not shown). The solid material may include one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers.

[0060] The hydrocarbon stream (102) is combined with the supplemental hydrogen (116) and the gas recirculation stream (112) and directed to the first-stage reactor HDT for hydrodenitrification and other reactions. This provides the hydrotreated hydrocarbon stream (104) by contacting materials with catalytic activity in the hydrotreatment process under active hydrotreatment conditions to provide a reduced organic-bound nitrogen content. The HDT step can advantageously be carried out in two reactor sections, with intermediate NH3 removal (typically by water washing) to shift the equilibrium towards denitrification.

[0061] This step reduces the potential catalyst passivation of catalytically active materials by ammonia and organic nitrogen in the downstream reactor. In this way, the method integrates multiple steps to efficiently produce hydrocarbon products from hydrocarbon-containing streams derived from various types of solid materials.

[0062] The hydrotreated hydrocarbon stream (104) is washed with water (106) and separated in a high-pressure separator (HPS) to obtain a gas stream (which is split into a gas recirculation stream (112) and an optional gas scavenging stream (114)), a polar liquid stream (115), and a non-polar liquid stream, namely the hydrotreated stream (118). The hydrotreated stream (118) is combined with the hydrogen-rich gas stream (130, 132) and the recirculation stream (120) and directed as a hydrodearomatization feed stream (119) to the hydrodearomatization (HDA) step to provide a hydrodearomatization stream (121) containing non-aromatization compounds that are more reactive than the corresponding aromatic compounds. Since the recirculation stream consists of hydrocarbons that have passed through the hydrodearomatization (HDA), the recirculation stream (120) can also be directed to be combined with the hydrodearomatization stream (121) depending on the degree of hydrodearomatization. The hydrodearomatization stream (121) is directed to a hydrocracking (HC) unit to provide a hydrocracking stream (122), to which wash water (124) is optionally added. The stream is then separated into a polar fraction (126), a gaseous fraction (128), and a non-polar fraction (136). The non-polar fraction (136) is sent to a fractionation (FRAC) unit to provide a vapor fraction (138), a product fraction (140), and a high-boiling fraction (144), as well as optional additional streams. A portion of the high-boiling fraction (144) is directed to a heated stripping column (HST), which also receives the stripping medium stream (146) (e.g., steam), while the remainder of the high-boiling fraction is directed as a recirculation stream (120) and combined with the hydrotreatment stream (118). The vapor outlet (142) of the heated stripper (HST) is directed to the fractionation column, and the liquid outlet (148) is directed to the sludge stream, with an optional portion (150) returned to the heated stripper (HST). This sludge stream will be enriched with very high-boiling fractions, which will contain increased concentrations of polycyclic aromatic hydrocarbons, such as non-aromatic polycyclic aromatic hydrocarbons, as well as any unconverted PNA and HPNA.

[0063] The recirculated stream (120) contains at least 50 wt%, for example 80 wt% or 90 wt%, of the high-boiling fraction, meaning that only a limited amount is directed to the heated stripping column (HST) and from there to the scavenging stream. This step separates the HPNA-rich stream from the lower-boiling fraction of the bottom stream. The lower-boiling fraction is then directed to a fractionation step or a hydrodearomatization step. The stripping step involves directing heat to the stripping stream to facilitate the separation process.

[0064] Figure 2

[0065] Figure 2Another embodiment of the process layout for producing hydrocarbon product (240) from a hydrocarbon stream (202) is shown. The hydrocarbon stream (202) originates from the thermochemical decomposition of a solid material (not shown). The solid material may include one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers.

[0066] The hydrocarbon stream (202) is combined with supplemental hydrogen (216) and gas recirculation stream (212) and directed to hydrodenitrification and other reactions in the first-stage reactor HDT, thereby providing a hydrotreated hydrocarbon stream (204) by contacting materials that are catalytically active in the hydrotreatment under active hydrotreatment conditions to provide a reduced organic-bound nitrogen content.

[0067] This step reduces the potential catalyst passivation of catalytically active materials by ammonia and organic nitrogen in the downstream reactor. In this way, the method integrates multiple steps to efficiently produce hydrocarbon products from hydrocarbon-containing streams derived from various types of solid materials.

[0068] The hydrotreated hydrocarbon stream (204) is washed with water (206) and separated in a high-pressure separator (HPS) to obtain a gas stream (which is split into a gas recirculation stream (212) and a gas scavenging stream (214)), a polar liquid stream (215), and a non-polar liquid stream, namely the hydrotreated stream (218). The hydrotreated stream (218) is combined with a hydrocracking product stream (221) containing a hydrogen-rich gas phase and directed to a hydrodearomatization (HDA) step to provide a hydrodearomatization combined stream (222) containing non-aromatic compounds that are more reactive than the corresponding aromatic compounds. Water (224) is optionally added to the hydrodearomatization combined stream (222), which is then high-pressure separated (HPS) into a polar fraction (226), a gas fraction (228), and a non-polar fraction (236), which is sent to a fractionation (FRAC) to provide a vapor fraction (238), a product fraction (240), and a high-boiling fraction (244), as well as optional additional streams.

[0069] A certain amount of high-boiling fraction (244) is directed to a heated stripping column (HST), which also receives a stripping medium stream (246) (e.g., steam), while the remainder of the high-boiling fraction is directed as a recirculation stream (220). The steam outlet (242) of the heated stripping column (HST) is directed to a fractionating column, while the liquid outlet (248) is directed to a sludge stream, with an optional portion of the recirculation (250) returning to the heated stripping column (HST). This sludge stream will be enriched with very high-boiling fractions, which will contain increased concentrations of polycyclic aromatic hydrocarbons, such as non-aromatic polycyclic aromatic hydrocarbons, as well as any unconverted PNA and HPNA. The recirculation stream (220) and the hydrogen-rich gas (230, 232) are directed to a hydrocracking (HC) step to provide a hydrocracking product stream (221).

[0070] In this embodiment, the content of aromatic compounds in the recycle stream (220) and the product (240) will be moderate because the entire stream (236) leading to the fractionation column (FRAC) will undergo a hydrodearomatization (HDA) step. Furthermore, a certain amount of HPNA precursors (including PNA and non-aromatic polycyclic structures) will be removed and purged from the liquid outlet (248) of the stripping column. Therefore, although the hydroprocessing stream (218) has a high potential for HPNA formation, the potential for HPNA formation during hydrocracking will be low.

[0071] Figure 3

[0072] Figure 3 Another embodiment of the process layout for producing hydrocarbon product (340) from a hydrocarbon stream (302) is shown. The hydrocarbon stream (302) originates from the thermochemical decomposition of a solid material (not shown). The solid material may include one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers.

[0073] The hydrocarbon stream (302) is combined with the supplemental hydrogen (316) and the gas recirculation stream (312) and directed to the first-stage reactor HDT for hydrodenitrification and other reactions, thereby providing a hydrotreated hydrocarbon stream (304) by contacting the hydrotreated material with a catalytically active material in the hydrotreatment under active hydrotreatment conditions to provide a reduced organic-bound nitrogen content.

[0074] This step reduces the potential catalyst passivation of catalytically active materials by ammonia and organic nitrogen in the downstream reactor. In this way, the method integrates multiple steps to efficiently produce hydrocarbon products from hydrocarbon-containing streams derived from various types of solid materials.

[0075] The hydrotreated hydrocarbon stream (304) is washed by adding water (306) and separated in a high-pressure separator (HPS) to obtain a gas stream (which is divided into a gas recirculation stream (312) and a gas scavenging stream (314)), a polar liquid stream (315) and a non-polar liquid stream, namely the hydrotreated stream (318).

[0076] In this embodiment, the hydrotreating stream (318) is fed to a fractionation (FRAC) to provide a vapor fraction (338), a product fraction (340), and a high-boiling fraction (344), as well as optional additional streams. This will provide a higher concentration of hydrogen peroxide than... Figure 1 and Figure 2 The product fraction has a higher aromatic content (340).

[0077] A certain amount of high-boiling fraction (344) is directed to a heated stripping column (HST), which also receives a stripping medium stream (346) (e.g., steam), while the remainder of the high-boiling fraction is directed as a recirculation stream (320). The steam outlet (342) of the heated stripping column (HST) is directed to a fractionation stream (FRAC), while the liquid outlet (348) is directed to a sludge stream, with an optional portion of the recirculation (350) returning to the heated stripping column (HST). This sludge stream will contain a very high-boiling fraction at an increased concentration, including polycyclic compounds (e.g., PNA and HPNA) and equivalent non-aromatic polycyclic compounds.

[0078] The remainder of the high-boiling fraction (320), along with hydrogen-rich gases (330, 332), is directed to a hydrodearomatization (HDA) step to provide a hydrodearomatization stream (321) containing non-aromatic compounds that are more reactive than the corresponding aromatic compounds. The hydrodearomatization stream (321) comprises a hydrogen-rich gas phase directed to hydrocracking (HC) to provide a hydrocracking stream (322), to which water (324) is optionally added, and then separated into a polar fraction (326), a gaseous fraction (328), and a non-polar fraction, which is combined with the hydrotreatment stream (318) as a fractionation feed stream (336) and sent to fractionation (FRAC) along with the hydrotreatment stream (318).

[0079] In this embodiment, the aromatic content in the recycle stream (320) will be high because only the recycle heavy stream has undergone the hydrodearomatization (HDA) step. Therefore, although a certain amount of HPNA precursors (including PNA and non-aromatic polycyclic structures) will be removed from the stripper in the liquid outlet (348), the potential for HPNA formation in hydrocracking may exist in the hydroprocessing stream (318), and the conditions of hydrocracking must be taken into account.

[0080] Figure 4

[0081] Figure 4 Another embodiment of the process layout for producing hydrocarbon product (440) from a hydrocarbon stream (402) is shown. The hydrocarbon stream (402) originates from the thermochemical decomposition of a solid material (not shown). The solid material may include one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers, and may be sewage sludge or industrial waste dispersion.

[0082] The hydrocarbon stream (402) is combined with supplemental hydrogen (416) and gas recirculation stream (412) and directed to hydrodenitrification and other reactions in one or more first-stage reactors (HDTs) to provide a hydrotreated hydrocarbon stream (404) by contacting materials that are catalytically active in the hydrotreatment under active hydrotreatment conditions to provide a reduced organic-bound nitrogen content.

[0083] This step reduces the potential catalyst passivation of the catalytically active material by ammonia and organic nitrogen in the downstream reactor. In this way, the method integrates multiple steps to efficiently produce hydrocarbon products from hydrocarbon-containing streams derived from various types of solid materials. The hydrotreated hydrocarbon stream (404) is washed with water (406) and separated in a high-pressure separator (HPS) to obtain a gas stream (which is split into a gas recirculation stream (412) and a gas scavenging stream (414)), a polar liquid stream (415), and a non-polar liquid stream, i.e., the hydrotreated stream (418).

[0084] In this embodiment, both the hydrotreated stream (418) and the purified hydrodearomatics stream (442) are fed to a fractionation (FRAC) to provide a vapor fraction (438), a product fraction (440), a high-boiling fraction (444), and optional additional streams. This will provide the aromatic product fraction (440).

[0085] Optionally, a high-boiling-point scavenging stream (452) is removed from the high-boiling-point fraction (444), and the remainder of the high-boiling-point fraction (420), along with makeup hydrogen (432) and recycled hydrogen-rich gas (430), is directed to a hydrodearomatization (HDA) step to provide a hydrodearomatization stream (421) containing non-aromatic compounds that are more reactive than the corresponding aromatic compounds. The hydrodearomatization stream (421) is directed to a hydrocracking (HC) unit to provide a hydrocracking stream (422), to which water (424) is optionally added, and then directed to a separator (HPS) to separate the stream into a polar fraction (426), a gaseous fraction (428), and a non-polar fraction (436), which is sent to a product stripping column (STRIP) that also receives stripping medium (437). The vapor fraction (439) from the product stripper (STRIP) is rich in light gases and is typically purged, but may contain combustible gases and is directed for separation or purification for use at other points in the process. The liquid fraction (441) from the product stripper is directed to a heated stripper (HST), which also receives a stripping medium stream (446) (e.g., steam). The vapor outlet (442) of the heated stripper (HST) is directed to the product stripper (STRIP) or fractionating column (FRAC), and the liquid outlet (448) is directed to a purge stream, optionally with a portion recycled (not shown) back to the heated stripper (HST). This purge stream will be rich in very high-boiling fractions, which will contain increased concentrations of polycyclic aromatic hydrocarbons (e.g., PNA and HPNA) as well as non-aromatic polycyclic aromatic hydrocarbons.

[0086] In this embodiment, the aromatic content in the recirculated stream (420) will be high because only the recirculated heavy stream has undergone the hydrodearomatization (HDA) step, but all HPNA and HPNA precursors will be removed in the liquid outlet (448), which makes this embodiment advantageous if the HPNA potential is high.

[0087] The accompanying figures illustrate the key principles of the disclosed process, but specific implementations may vary. This includes the specific configuration of hydrogen addition, process heating, and separation, as well as other elements known to those skilled in the art. Furthermore, individual process elements such as pumps, compressors, and heat exchangers may be required and implemented by those skilled in the art. Additionally, the figures show single output products (140, 240, 340, and 440), which are typically fractionated into two or more of naphtha, aviation fuel, and diesel fuel. If such product streams contain aromatic compounds exceeding limits, they can also be separated into fractions directed to hydrodearomatication via recycling or downstream fractionation.

[0088] Finally, for Figure 1 and Figure 2 The implementation scheme (in which the entire hydrotreating stream (118, 218) is directed to hydrodearomatization (HDA)) and Figure 3 and Figure 4 The proposed implementation (where the entire hydrotreating stream (318, 418) is directed to a fractionation column (FRAC)) also has alternative configurations where the stream can be split (either into streams of the same composition or in a hot gas-liquid separator), with one portion directed to the FRAC and the other to hydrodearomatization (HDA). This results in higher aromatic product concentrations but a smaller HDA reactor, thus leading to lower capital and operating costs. This splitting can even be configured for dynamic operation to accommodate changes in requirements due to feedstock or product mixing.

[0089] Since HPNA may not pose a problem in large-bore engines (such as marine engines), the process can also be designed to combine a certain amount of high-boiling-point fractions (144, 244, 344, 444) with the scavenging stream (148, 248, 348, 448) for use as marine fuel, or alternatively, to configure a heated stripping tower to direct higher fractions to the scavenging stream.

[0090] Description of the implementation plan

[0091] A broad aspect of this disclosure relates to a method for producing hydrocarbon products from a hydrocarbon-containing stream derived from the thermochemical decomposition of a solid renewable material, the method comprising the following steps: (a) The hydrocarbon-containing stream is directed to the hydrotreating step to provide a hydrotreating stream. (b) At least 80 wt% of the T90 to T95 fraction of the hydrotreating stream is directed to the hydrodearomatization step to provide a hydrodearomatization stream. (c) Directing a hydrocracking feed stream containing at least a certain amount of hydrodearomatics stream to a hydrocracking step to provide a hydrocracking stream. (d) Fractionating a fractionated feed stream comprising one or both of a hydrodearomatization stream and a hydrocracking stream to provide the hydrocarbon products and at least 80 wt% of a high-boiling fraction comprising the T90 to T95 fractions of the fractionated feed stream, characterized in that step d includes a sub-step of removing a stream having an average boiling point higher than that of the high-boiling stream and directing 1% to 50% as a stream rich in heavy polynuclear aromatics, wherein the stream rich in heavy polynuclear aromatics has a higher mass concentration of heavy polynuclear aromatics than that of the high-boiling stream.

[0092] The relevant benefits are that processing feedstocks with a tendency to form HPNAs through hydrotreatment, hydrodearomatization, and hydrocracking reduces the risk of downstream catalyst passivation and increases fraction reactivity by removing heteroatoms; it reduces the tendency to form HPNAs by hydrodearomatizing at least the heavy fraction; and it provides the possibility of recycling most of the heaviest stream for further reaction by hydrocracking and ring-opening at least a portion of the hydrodearomatized stream and fractionating one of the reaction streams, while the highest boiling point fraction can be removed to the purge stream. The hydrocracking feed stream may include the entire hydrodearomatized stream, a portion of the hydrodearomatized stream with substantially the same composition, or a stream fractionated from the hydrodearomatized stream. Streams rich in heavy polynuclear aromatics can be removed from the purge stream, and higher heavy polynuclear aromatic mass concentrations than those of the high-boiling point stream can be achieved by using selective adsorbents, separation by specific stripping configurations, or liquid extraction. The purge stream should be understood as the stream removed and not directed to any step ad in an untreated manner. The cleanup stream can be burned, undergo a chemical reaction, or collected as chemical waste.

[0093] A second aspect of this disclosure relates to a stripping step that receives stripping column feed and stripping medium feed, directs stripping column vapor to the fractionation column, and directs a portion of the stripped liquid to a purging stream. The mass flow rate of the stripping liquid directed to the stripping stream is 1% to 50% of the mass flow rate of the stripping tower feed, and the stripping tower feed includes at least 50 wt% of the hydrocracking stream or the high-boiling fraction stream.

[0094] The relevant benefit of this is that this stripping step effectively separates and directs the high-boiling fraction rich in polynuclear aromatics (PNAs) to the scavenging stream, thereby minimizing the formation of heavy polynuclear aromatics (HPNAs) as a side reaction during hydrocracking, while allowing additional ring-opening and conversion to low-boiling compounds.

[0095] The third aspect of this disclosure relates to a method according to the second aspect, wherein a fractionation feed stream is directed to a stripping tower, stripping tower vapor is directed to the fractionation tower, and stripping liquid is directed as a stream rich in heavy polynuclear aromatics.

[0096] The relevant benefit is that the stripping step is an efficient method for selectively separating heavy polynuclear aromatic hydrocarbons (HPNAs) from other high-boiling-point streams, especially if a large amount of HPNAs are present.

[0097] The fourth aspect of this disclosure relates to a method according to the second aspect, wherein a fractionation feed stream is directed to a fractionation column and a bottom stream from the fractionation column is directed to a stripping step, a stream rich in heavy polynuclear aromatics is separated from a lower boiling point fraction of the bottom stream, and wherein the lower boiling point stream is directed to a fractionation step or a hydrodearomatics step.

[0098] The relevant benefit is that the stripping step is an effective way to avoid HPNA recycling.

[0099] A fifth aspect of this disclosure relates to a method according to the third or fourth aspect, wherein the stripping step includes directing heat into the stream flowing to the stripping step.

[0100] The relevant benefit of this is that the heating stripping process allows stripping to occur at or above the bubble point of the high-boiling fraction, thereby promoting the effective separation of HPNA from other high-boiling fractions.

[0101] The sixth aspect of this disclosure relates to a method according to any of the foregoing aspects, wherein the nitrogen content of the hydrogenation treatment stream is less than 200 ppmwt, 100 ppmwt, or 50 ppmwt, and optionally more than 100 ppbwt, 1 ppmwt, or 10 ppmwt of organically bound nitrogen.

[0102] The relevant benefit of this is that it minimizes catalyst passivation, which could otherwise limit the hydrodearomatization and hydrocracking of hydrocarbon streams. The same step can also convert oxygen-containing and sulfur-containing compounds, or such conversions can be carried out in a separate hydrotreating step. Typically, the hydrodenitrogenation product stream is separated into liquid and gas phases, with only the liquid phase being transferred to further process steps. A nitrogen content of 200 ppmwt, 100 ppmwt, or below 50 ppmwt reduces the tendency for passivation in downstream hydrodearomatization and hydrocracking catalysts, while the optional incomplete removal of nitrogen allows residual nitrogen to be removed through reactions on downstream catalysts.

[0103] The seventh aspect of this disclosure relates to a method according to any of the preceding aspects, wherein step c includes directing a stream from a fractionating column containing at least the high-boiling fraction to the hydrocracking step, and wherein the fractionating column has received the hydrodearomatics stream.

[0104] The relevant benefit of this is that the stream with a moderate aromatic content can be recycled to hydrocracking, which allows for milder hydrocracking conditions, thereby reducing yield loss while avoiding the extensive formation of HPNA.

[0105] The eighth aspect of this disclosure relates to a method according to any of the foregoing aspects, wherein step c includes directing a stream from a fractionating column containing at least the high-boiling fraction to the hydrodearomatics step and directing the hydrodearomatics stream to the hydrocracking step.

[0106] The related benefit is that it allows streams with high aromatic content to be recycled to hydrocracking while avoiding the widespread formation of HPNA.

[0107] The ninth aspect of this disclosure relates to a method according to any of the preceding aspects, wherein step d includes directing a hydrocracking stream and a hydroprocessing stream to the fractionation step, and wherein the hydrodearomatic step receives a stream comprising at least the high-boiling fraction.

[0108] The associated benefit is a reduction in the amount directed to hydrodearomatization and hydrocracking, which reduces the required catalyst volume and yield losses due to the hydrocracking of low-boiling hydrocarbons. In this case, the hydrocarbon products can contain an increased content of aromatic compounds.

[0109] The tenth aspect of this disclosure relates to a method according to any of the foregoing aspects, wherein at least a certain amount of T95+ fraction from the fractionation section, as well as hydrocracking stream and hydrotreatment stream, are directed to the fractionation step.

[0110] The relevant benefit of this is that separation sections, including one or more of stripping columns, separators, and fractionating columns, can separate a first useful product fraction that requires almost no hydrogen consumption from other fractions that require more hydrogen consumption. The first useful product fraction can be a high-boiling-point fraction that can be used as marine fuel, while the other fractions can be aviation fuel or diesel fuel subject to more stringent regulatory and trade standards.

[0111] The eleventh aspect of this disclosure relates to a method according to any of the foregoing aspects, further comprising guiding a solid material comprising one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers to a thermochemical decomposition process to provide the hydrocarbon-containing stream.

[0112] The relevant benefit is that, due to the dominance of polycyclic aromatic structures in the solid materials, such solid materials have the potential to produce hydrocarbon streams with high polycyclic aromatic hydrocarbon content.

[0113] A further aspect includes process equipment for performing the method according to any one of the preceding claims.

[0114] Example

[0115] The feed stream from the thermochemical decomposition of wastewater sludge was analyzed, and its treatment was simulated through a combination of pilot-scale experiments and calculations. The feed contained 83 wt% C, 9 wt% H, 8 wt% O, and 681 ppmwt N, as well as trace impurities not considered here.

[0116] according to Figure 1 and Figure 3 The flow composition is shown in Tables 1 and 2, where all reported values ​​pertain only to the C5+ fraction, i.e., the fraction that is liquid under ambient conditions.

[0117] Table 1 shows the following... Figure 1 The process shown demonstrates performance where all hydrotreatment streams are directed to hydrodearomatization and further to hydrocracking. The liquid phase of the hydrotreatment stream contains 5 ppmwt N and can therefore be considered pure hydrocarbons. The process also includes recycling of heavy products for multi-pass hydrocracking. It can be seen that the hydrotreatment stream (of the C5+ fraction) has a suitable H:C ratio of 1.59 before being combined with the recycled high-boiling fraction. The process produces a distillate product yield of 73 t / h with an aromatic content of 10 wt%.

[0118] Table 2 shows the following... Figure 3 The performance of the process shown, wherein the hydrogenation process stream (its liquid phase and...) Figure 1 (Similar) The stream is directed to fractionation, and only the high-boiling fraction is directed to hydrodearomatization and further to hydrocracking. The stream directed to hydrodearomatization has a very low H:C ratio of 1.48, but still allows for hydrodearomatization and hydrocracking, and the risk of HPNA buildup is minimal due to scavenging in stream 348. The process produces a yield of 80 t / h with an aromatic content of 48 wt%, which may be acceptable for some transport fuels. Due to the smaller processed stream, the required hydrodearomatization and hydrocracking catalyst volumes are significantly smaller than those of the stream. Figure 1 The volume.

[0119] This process can be further adjusted based on the requirements for the product and the properties of the raw materials. If the raw materials contain a high amount of high-boiling-point products, the recycling rate can be increased, and if based on... Figure 3 If the aromatic compound content in the product is too high, a portion of the hydrogenation process stream (318) can be combined with the recycling stream to obtain a process that includes both process elements.

[0120] Table 1

[0121] Table 2

Claims

1. A method for producing hydrocarbon products from a hydrocarbon-containing stream derived from the thermochemical decomposition of a solid renewable material, the method comprising the following steps: a. Directing the hydrocarbon-containing stream to the hydrotreating step to provide a hydrotreating stream. b. At least 80 wt% of the T90 to T95 fraction of the hydrotreating stream is directed to the hydrodearomatization step to provide a hydrodearomatization stream. c. Directing the hydrocracking feed stream, which contains at least a certain amount of hydrodearomatics stream, to the hydrocracking step to provide a hydrocracking stream. d. Fractionating the fractionated feed stream comprising one or both of a hydrodearomatization stream and a hydrocracking stream to provide the hydrocarbon products and at least 80 wt% of a high-boiling fraction comprising the T90 to T95 fraction of the fractionated feed stream. The characteristic feature is that step d includes a sub-step of taking out a stream having an average boiling point higher than that of the high-boiling-point stream and directing 1% to 50% of it as a stream rich in heavy polynuclear aromatics, wherein the stream rich in heavy polynuclear aromatics has a higher mass concentration of heavy polynuclear aromatics than the high-boiling-point stream.

2. The method of claim 1, further comprising a stripping step, the stripping step receiving stripping tower feed and stripping medium feed, directing stripping tower vapor to the fractionation tower, and directing a certain amount of stripped liquid to a purge stream, wherein the mass flow rate of the amount of stripped liquid directed to the purge stream is 1% to 50% of the mass flow rate of the stripping tower feed, and wherein the stripping tower feed comprises at least 50 wt% of the hydrocracking stream or the high-boiling fraction stream.

3. The method of claim 2, wherein the fractionation feed stream is directed to the stripping tower, the stripping tower steam is directed to the fractionation tower, and the stripping liquid is directed as a stream rich in heavy polynuclear aromatics.

4. The method of claim 2, wherein the fractionation feed stream is directed to a fractionation column and the bottom stream from the fractionation column is directed to a stripping step, the stream rich in heavy polynuclear aromatics is separated from the lower boiling point fraction of the bottom stream, and wherein the lower boiling point stream is directed to a fractionation step or a hydrodearomatics step.

5. The method according to claim 3 or 4, wherein the stripping step includes directing heat to the stream in the stripping step.

6. The method according to any of the preceding claims, wherein the nitrogen content of the hydrogenation treatment stream is less than 200 ppmwt, 100 ppmwt, or 50 ppmwt, and optionally more than 100 ppbwt, 1 ppmwt, or 10 ppmwt of organically bound nitrogen.

7. The method according to any of the preceding claims, wherein step c comprises directing a stream from a fractionating column containing at least the high-boiling fraction to the hydrocracking step, and wherein the fractionating column has received the hydrodearomatics stream.

8. The method according to any of the preceding claims, wherein step c comprises directing a stream from a fractionating column containing at least the high-boiling fraction to the hydrodearomatization step and directing the hydrodearomatization stream to the hydrocracking step.

9. The method according to any of the preceding claims, wherein step d includes directing the hydrocracking stream and the hydrotreatment stream to the fractionation step, and wherein the hydrodearomatization step receives a stream comprising at least the high-boiling fraction.

10. The method according to any of the preceding claims and in combination with claim 6, wherein at least a certain amount of the T95+ fraction from the fractionation section, as well as the hydrocracking stream and the hydrotreatment stream, are directed to the fractionation step.

11. The method according to any of the preceding claims, further comprising guiding a solid material comprising one or more compounds selected from lignin, cellulose, hemicellulose, lipids, proteins, and synthetic polymers to a thermochemical decomposition process to provide the hydrocarbon-containing stream.

12. A process apparatus for performing the method according to any of the preceding claims.

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