Method for recovering hydrogen during hydroprocessing of feedstock containing oxygenated compounds

Abstract

The present invention relates to a process and a process plant for partial hydroprocessing of a feedstock comprising oxygenates, the process comprising the steps of: introducing the feedstock, an amount of supplemental hydrogen and a recycle gas into a catalytic hydroprocessing process under conditions that convert 30-95% of the oxygenates to hydrocarbons, to provide a partially hydroprocessed product stream; adding an amount of recycled wash water (comprising at least 0.1 wt% of oxygenates) to at least an amount of the hydroprocessed product stream, optionally mixed with an additional amount of wash water to provide a mixed hydroprocessed product stream; cooling and separating the mixed hydroprocessed product stream into a gas phase product fraction, a liquid aqueous fraction, and a liquid product fraction; a first amount of the liquid aqueous fraction is discharged as a waste stream (by a discharge or purification process) and at least a second amount of the liquid aqueous fraction is directed as the amount of recycled wash water. The method has the advantages that the washing water is at least partially saturated by the oxygen-containing compound, so that the discharge of the oxygen-containing compound in the washing water can be reduced to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the field of upgrading liquids originating from the thermal decomposition of solid feedstocks.

[0002] Technical issues

[0003] Oxygenates derived from the thermal decomposition of biomass or solid feedstocks such as mixed municipal waste, mixed or sorted plastic waste and forestry waste provide a liquid product (referred to as pyrolysis oil or crude pyrolysis oil for simplicity) that can be upgraded to high-quality hydrocarbons and used as transportation fuels or petrochemical feedstocks. The oxygenate content of the product may also be higher than is normally required for hydrocarbon transportation fuels, perhaps for subsequent hydroprocessing at a different location, or for the intention to use such an oxygenate-rich product.

[0004] When the final product is rich in oxygenates, the processing conditions and intermediate products will be different from other hydroprocessing methods (in which the intermediates and final products are quantitatively converted to hydrocarbons). This also means that the intermediate methods used to purify the intermediate products will be different, especially the presence of oxygenates in the product will cause more product to dissolve in the wash water, which may lead to yield losses.

[0005] We have determined that this yield loss can be reduced by recycling all or part of the wash water, allowing the wash to be carried out with a stream which no longer has the capacity to extract oxygenates because it is already saturated with oxygenates.

[0006] definition

[0007] It will be understood that the unit "MPag" means megapascal gauge pressure, ie, pressure above ambient pressure.

[0008] It should be understood that the unit Nm 3 It represents the "standard" cubic meter, that is, the volume occupied by a gas at 0°C and 1 atmosphere of pressure.

[0009] As used herein, the term "hydrogen / liquid oil ratio" or "H2:oil ratio" refers to the volume ratio of the hydrogen gas stream to the liquid oil stream and is expressed in Nm 3 / m 3 denoted as, where the gas phase is reported under standard conditions (0°C and 1 atm) and the liquid phase is reported under standard conditions (25°C and 1 atm), which is consistent with the practice in the art.

[0010] When concentration is expressed in wt %, it is to be understood as weight / weight percentage.

[0011] When referring to the concentration of oxygenates or other groups of molecules, it is understood to be the concentration of all molecules in the group, not the concentration of functional groups.

[0012] As used herein, for convenience, the terms "thermal decomposition" and "thermochemical decomposition" should be used broadly to refer to any decomposition process in which a solid material is partially decomposed under high temperature (typically 250°C to 800°C, or even 1000°C) and substoichiometric amounts of O2 (including without added oxygen). The product is typically a mixed stream of liquid and gas, as well as a certain amount of solid char. The term should be interpreted as including pyrolysis and hydrothermal liquefaction processes with or without a catalyst. For convenience, the product of such a thermal decomposition process may be referred to as pyrolysis oil, but it should be understood to cover any thermal decomposition process.

[0013] In the following, the term "hydrocarbonaceous feedstock" is used to denote a feedstock rich in molecules of hydrogen and carbon, but which may also contain heteroatoms, ie other elements such as oxygen, sulfur and nitrogen.

[0014] As used herein, the term "stage" refers to a physical stage comprising one unit or a combination of multiple units for performing one or more steps and / or sub-steps.

[0015] The terms "raw material of plastic or polymer origin" or "waste plastic or polymer" are understood to mean mixed or sorted waste comprising at least 50 wt%, 80 wt% or 90 wt% of plastics and other synthetic polymers.

[0016] Raw materials of biological origin can be defined by their origin, but can also be identified by their 14 The C content is defined as 0.5 ppt (parts per trillion) or more of the total carbon content.

[0017] When referring to hydrogen gas and hydrogen concentration, unless otherwise specified, it is generally understood to refer to elemental hydrogen in a molecular state and not hydrogen in other molecular parts.

[0018] When referring to oxygen content, unless otherwise specified, it is generally understood to refer to atomic oxygen as part of other molecules rather than molecular oxygen.

[0019] Technical solutions to the problem

[0020] The conversion of pyrolysis oil into stable products containing appropriate amounts of oxygenates can be carried out in a cost-effective manner by partial hydrotreatment, thereby reducing the consumption of hydrogen.

[0021] The conversion of oxygenates to transportation fuels by partial hydroprocessing will provide a product that is partially soluble in water. In order to minimize yield losses, it is recommended to use a wash water containing oxygenates, such as recycled wash water, even if it contains other impurities. Thus, additional oxygenate product will not be carried away by the wash water.

[0022] According to the present disclosure, hydrocarbon feedstock can be provided by a thermochemical decomposition process equipment section, which can be one of a variety of variants, including rotary kiln, fluidized bed, conveyor bed or circulating fluidized bed, as is well known in the art. The decomposition process converts the pyrolysis feedstock into solids (char), high boiling liquids (tar) and fractions that are gaseous at high temperatures. The gaseous fractions include fractions that are condensable at standard temperature (pyrolysis oil or condensate, C 5+ Compounds) and non-condensable fractions (pyrolysis gases, including pyrolysis tail gas). For example, a thermochemical decomposition process equipment section (pyrolysis section) may include a pyrolysis unit (pyrolysis reactor), a cyclone separator and / or a filter to remove particulate solids such as char, and a cooling unit to generate a pyrolysis tail gas stream and the pyrolysis oil stream, i.e., condensed pyrolysis oil. The pyrolysis gas stream contains light hydrocarbons (e.g., C1-C4 hydrocarbons), and typically also contains H2O, CO, and CO2. Typically, the term "pyrolysis oil" includes condensates and tars, while the pyrolysis oil stream from biomass pyrolysis may also be referred to as bio-oil or bio-crude oil. Pyrolysis oil is a liquid substance rich in a variety of molecular mixtures, typically consisting of more than two hundred different compounds, primarily including oxygenated compounds such as acids, sugars, alcohols, phenols, guaiacol, eugenol, aldehydes, ketones, furans, and other mixed oxygenated compounds, which originate from the depolymerization of solids treated during the pyrolysis process. Thermochemical decomposition of non-biomass waste containing suitable components (such as plastic fractions or rubber, including scrap tires) generally only provides products with low oxygen content unless O2 is added to the decomposition process, and generally provides a hydrocarbonaceous feedstock that reflects the structure of the solid pyrolysis feedstock.

[0023] For the purposes of the present invention, the pyrolysis stage may be a fast pyrolysis, also known in the art as flash pyrolysis. Fast pyrolysis refers to the thermochemical decomposition of solid raw materials under conditions generally without O2, in a temperature range of 350-650°C (e.g., about 500°C), with a reaction time of 10 seconds or less (e.g., 5 seconds or less, such as about 2 seconds). Fast pyrolysis may be performed, for example, by autothermal operation, for example in a fluidized bed reactor. The latter, also known as autothermal pyrolysis, is characterized in that air (optionally mixed with an inert gas or a recycled gas) is used as a fluidizing gas. Thus, partial oxidation of the pyrolysis compounds produced in the pyrolysis reactor (autothermal reactor) provides energy for pyrolysis while improving heat transfer. In so-called catalytic fast pyrolysis, a catalyst may be used. Acidic catalysts (usually comprising zeolites and free of active metals) may be used to upgrade pyrolysis steam and may be operated in an in-situ mode (the catalyst is located in the pyrolysis reactor) and an ex-situ mode (the catalyst is placed in a separate reactor). The advantage of using a catalyst is that it helps stabilize the pyrolysis oil, making it easier to hydroprocess. In addition, the selectivity to the desired pyrolysis oil compounds can be improved.

[0024] In some cases, hydrogen is added to the catalytic pyrolysis, which is called reactive catalytic fast pyrolysis. If the catalytic pyrolysis is carried out at a higher hydrogen pressure, such as above 0.5 MPa, it is usually called catalytic hydropyrolysis. The catalyst used for upgrading in the presence of hydrogen usually contains one or more metals with hydrogenation activity, such as metals of Group 6 or Groups 8, 9, and 10.

[0025] The pyrolysis stage may be a fast pyrolysis, which is carried out without the use of a catalyst and hydrogen, i.e. the fast pyrolysis stage is not catalytic fast pyrolysis, hydropyrolysis or catalytic hydropyrolysis. This makes the process simpler and less costly.

[0026] In one embodiment, thermal decomposition is hydrothermal liquefaction. Hydrothermal liquefaction refers to a thermochemical conversion process in which solid raw materials (such as plastic waste, biomass, municipal solid waste or sewage sludge) are treated in a high temperature and high pressure water environment for a sufficiently long time to decompose the solid biopolymer structure into mainly liquid components. Typical hydrothermal processing conditions are temperatures in the range of 200-500°C, especially 300-450°C, and operating pressures in the range of 4-40MPag, especially 25-35MPag. Compared with pyrolysis (such as fast pyrolysis), this technology has the advantages of lower operating temperature, higher energy efficiency and lower yield of high boiling point products.

[0027] In one embodiment, the pyrolysis further comprises passing the solid feedstock through a solid feedstock preparation section, for example, including drying to remove moisture and / or comminution to reduce particle size. Any moisture / humidity in the solid feedstock, after evaporation in, for example, the pyrolysis section, will condense in the pyrolysis oil stream and thus be carried into the process, which may be undesirable. In addition, the heat used for evaporation of the water consumes the heat that would otherwise be used for pyrolysis. By removing moisture and providing a solid feedstock of smaller particle size, the thermal efficiency of the pyrolysis section is improved.

[0028] Finally, other related thermochemical decomposition methods include moderate or slow pyrolysis, where conditions involve lower temperatures and generally longer residence times - these methods may also be referred to as carbonization or calcination. The main advantage of these thermochemical decomposition methods is lower investment, but they may also have specific advantages for specific feedstocks or specific product requirements (e.g. the desire to obtain biochar as a by-product).

[0029] When large amounts of solid products are generated, such as in processes for producing biochar or when it is desirable to recover unconverted carbon black particles from thermochemical conversion of end-of-life tires, it may be beneficial to filter the liquid products as part of the thermochemical conversion process, which also helps minimize deactivation of downstream catalysts.

[0030] Liquid feedstocks obtained by thermochemical decomposition are not of sufficient quality to be used as, for example, transportation fuels. They may have problems such as high boiling points, poor stability, and contain undesirable heteroatoms, and therefore need to be upgraded to feedstocks with practical and economic value by hydroprocessing.

[0031] Therefore, we propose a method for hydrotreating a liquid oil stream by reacting the liquid oil stream with hydrogen in the presence of a hydrotreating catalyst that is resistant to sulfur poisoning. The catalyst can be a sulfided catalyst comprising one or more of nickel, cobalt, molybdenum and tungsten, typically operating at an inlet temperature of 130-200°C; or it can be a metallic catalyst comprising one or more of nickel, palladium and platinum, typically operating at an inlet temperature of 80-130°C. In most cases, the pressure can be 0.5-2MPa, but can also be as high as 15MPa, and the liquid hourly space velocity (LHSV) is 0.1-5h-1, which can form a stable liquid oil stream.

[0032] In one embodiment, the hydroprocessing catalyst is in a sulfided form, such as NiMoS or CoMoS. The catalyst may be presulfided by exposure to a sulfur-containing stream, or may be sulfided in situ, i.e., during operation or immediately prior to operation, such as by sulfur present in pyrolysis oil, such that the sulfided catalyst remains sulfided and therefore active due to the presence of sulfur.

[0033] Materials that are catalytically active in the initial hydroprocessing, especially in the hydroprocessing of conjugated double bonds, typically comprise an active metal (sulfided base metals such as nickel, cobalt, tungsten and / or molybdenum, but may also include elemental metals such as nickel and precious metals such as platinum and / or palladium) and a refractory support such as alumina, silica or titania, or a combination thereof. Initial hydroprocessing conditions may involve moderate temperatures of 120-200°C, moderate pressures of 0.5-5 MPa, and liquid hourly space velocities (LHSV) of 0.1-5. Under certain conditions, higher pressures of up to 15 MPa may be required.

[0034] Final hydrotreating (e.g., hydrogenation) conditions typically involve elevated temperatures in the range of 250-400°C, elevated pressures in the range of 3-15 MPa, and liquid hourly space velocities (LHSV) in the range of 0.1-4, optionally with intermediate cooling by quenching with cold hydrogen, feed, or product. Typically, lower severity can be achieved by reducing temperature, increasing space velocity, limiting catalyst activity, or reducing hydrogen availability, thereby limiting the extent of conversion of oxygenates to hydrocarbons, which will reduce hydrogen consumption. One skilled in the art will know how to select conditions suitable for the desired severity in this multidimensional space by routine experimentation.

[0035] Typically, the process is moderately exothermic so an exotherm of 5-20°C typically occurs, but depending on the extent of hydrogenation and hydrodeoxygenation it can be highly exothermic with exotherms of up to 100°C.

[0036] In addition to the removal of heteroatoms by hydrotreating, additional steps may be required to obtain a product of suitable quality. These steps may include isomerization, hydrocracking and hydrodearomatization, among others, depending on the feedstock characteristics and product requirements.

[0037] Materials having catalytic activity in isomerization generally comprise an active metal (elemental noble metals such as platinum and / or palladium, or sulfided base metals such as nickel, cobalt, tungsten and / or molybdenum), an acidic support (generally a molecular sieve with high shape selectivity, with topologies such as MOR, FER, MRE, MWW, AEL, TON and MTT) and a refractory support (such as alumina, silica or titania, or a combination thereof).

[0038] The isomerization conditions involve a temperature in the range of 250-400°C, a pressure in the range of 2-10 MPa and a liquid hourly space velocity (LHSV) in the range of 0.5-8.

[0039] The materials catalytically active in hydrocracking are of similar nature to those catalytically active in isomerization, and generally comprise active metals (elemental noble metals, such as platinum and / or palladium, or sulfided base metals, such as nickel, cobalt, tungsten and / or molybdenum), an acidic support (generally a molecular sieve with high cracking activity, with topologies such as MFI, BEA and FAU) and a refractory support (such as alumina, silica or titania, or a combination thereof). The difference compared to the materials catalytically active in isomerization generally lies in the nature of the acidic support, which may have a different structure (even amorphous silica-alumina can be used for hydrocracking) or have a different acidity, for example due to a different ratio of silica to alumina.

[0040] Hydrocracking conditions may involve temperatures in the range of 250-400°C, pressures in the range of 3-20 MPa and liquid hourly space velocities (LHSV) in the range of 0.5-8, optionally with the simultaneous use of intermediate cooling by quenching with cold hydrogen, feed or product.

[0041] Other types of hydroprocessing are also contemplated, such as hydrodearomatization (HDA). Materials catalytically active in hydrodearomatization typically comprise an active metal (typically an elemental noble metal such as platinum and / or palladium, but may also be a sulfided base metal such as nickel, cobalt, tungsten and / or molybdenum) and a refractory support such as amorphous silica-alumina, alumina, silica or titania, or a combination thereof.

[0042] The hydrodearomatization conditions involve a temperature in the range of 200-350°C, a pressure in the range of 2-10 MPa, and a liquid hourly space velocity (LHSV) in the range of 0.5-8.

[0043] There are significant costs involved in providing hydrogen for hydroprocessing and reducing hydrogen demand can be a driver for cost reduction. In hydroprocessing, a certain amount of hydrogen is consumed per unit volume of oil, which is called the H2:oil consumption ratio. Depending on the nature of the crude product, for full hydroprocessing, the H2:oil consumption ratio may be 50Nm 3 / m 3 Up to 1000Nm 3 / m 3 However, to minimize the risk of coke deposition on the catalyst due to hydrogen starvation, it is common to operate with a safety factor of 2, 4 or even 8, e.g. an H2:oil consumption ratio of 200 Nm 3 / m 3 When operating, up to 1000Nm may be used 3 / m 3 H2: Oil.

[0044] Typically, hydroprocessing, especially when processing oxygenate feedstocks, is carried out with an excess of hydrogen to increase the reaction rate and minimize the risk of coke deposition on the catalyst. Excess hydrogen is often recycled to reduce hydrogen consumption and associated costs. However, since the reaction rate and process equilibrium depend on the partial pressure of hydrogen, the presence of other compounds in the recycle gas, such as methane and carbon dioxide, can reduce the effectiveness of hydrogen or require an increase in the total pressure, which can result in higher equipment costs. For example, if the H2:oil consumption ratio is 200 Nm 3 / m 3 , and the purity of the hydrogen-rich gas in the process is only 80 vol%, then with a safety factor of 2, the gas: oil ratio will reach 500 Nm 3 / m 3 .

[0045] The product stream of hydroprocessing will be a gas / liquid two-phase stream. The liquid phase will be a product with a quality suitable for final products or downstream processing, which may contain a large amount of high-boiling hydrocarbons and oxygenates, while the hot gas phase will contain unreacted hydrogen and gaseous products. The gaseous products are mainly released heteroatoms, including oxygen (in the form of H2O or CO and CO2), nitrogen (in the form of NH3), sulfur (in the form of H2S) and halides such as chlorides (in the form of HCl or NH4Cl). In addition, light hydrocarbons and oxygenates may also be present in the hot gas phase, especially in the case of incomplete hydrogenation. Due to the presence of excess hydrogen and its associated costs, it is desirable to recycle the hydrogen.

[0046] Typically, the liquid phase will be separated from the gas phase in a hot, high-pressure separator (operated at near process conditions, e.g., 11 MPa and 240°C). If all catalysts are sulfided and the process is operated in the presence of sulfur, this separation can be performed downstream of the full hydroprocessing process, but typically only the initial hydrotreating step uses sulfided catalyst, in which case the first step of the separation will be performed downstream of the hydrodeoxygenation and upstream of the precious metal isomerization or hydrocracking catalyst. If the additional (or all) catalysts are sulfided, the separation is typically performed after all sulfided catalysts.

[0047] The gas phase will contain excess H2, small molecular heteroatom compounds (such as H2O, CO, CO2, NH3, H2S and HCl) and C1-C5 hydrocarbons and oxygen-containing compounds. In order to separate the excess H2 from the rest of the gas phase, the gas phase can be cooled to, for example, 50°C and separated in a high-pressure cold separator.

[0048] If the hot gas phase contains water and light hydrocarbons, condensation in the cold separator will produce three phases: a gas phase, a liquid non-polar phase rich in hydrocarbons, and a liquid polar phase rich in water. Most non-polar gases (such as CO2, CO and alkanes) have high solubility in the liquid non-polar phase, while salts (such as NH4Cl) have high solubility in the polar phase, so these compounds can be discharged from the high-pressure cold separator with the liquid condensate, while H2 will mainly remain in the gas phase due to its low solubility.

[0049] Salts (such as ammonium chloride) are not desirable in the product and may solidify on the equipment. In order to remove such impurities, a certain amount of washing water is usually added after the hot separator, because salts have a high solubility in liquid water and are easily separated from the gas stream by lowering the temperature. Thus, salts can be removed from the liquid product. However, when the product is only subjected to partial hydrotreatment, it contains a certain amount of oxygenates, which are partially soluble in water. This means that the step of product purification by adding washing water will not only remove salts, but also a certain amount of oxygenates, which could be valuable products.

[0050] The actual process of adding the scrubbing water involves mixing liquid water with the hot stream, preferably under conditions (pressure, temperature, relative amount of water) that result in only a partial evaporation of the water, since a certain amount of liquid water is very beneficial to the scrubbing process, especially when the product is in the liquid phase. The mixed stream is then cooled to form a liquid product phase, a liquid water phase, and a gas phase. Hydrocarbons are non-polar and have very low solubility in water, so only ppm wt Concentrated hydrocarbons will enter the water phase. On the other hand, oxygenated compounds are more polar and have a certain solubility in water, depending on the characteristics of the oxygenated compounds. Therefore, a certain amount of oxygenated compounds (which should be products) will be carried away with the wash water.

[0051] In order to minimize the amount of product carried over with the wash water, we recommend using wash water that is at least partially saturated with oxygenates. This can be achieved in a cost-effective manner by recycling the wash water, but in this case it is desirable to recycle the wash water containing dissolved oxygenates, as opposed to the common practice of purifying the wash water prior to recycling. In this way, additional oxygenates are not carried over, and a higher overall process yield can be achieved.

[0052] A certain amount of the liquid water phase must be discharged to ensure that salts do not accumulate in the wash water. This can be done by discharge to the general wastewater treatment system or by purifying the water in a closed loop system, e.g. by concentrating it by evaporation and recycling the purified water. When determining the discharge amount, the water produced during the hydrodeoxygenation process must also be taken into account. Typically, this water will be a significant contributor to the wash water consumption in the process.

[0053] However, if the product is only partially hydrotreated, the amount of condensed non-polar hydrocarbons is low. This is especially true if the feedstock is a high-boiling substance, since in this case most of the liquid product at ambient conditions has already been discharged in the high-pressure and high-temperature separator. In addition, if the amount of condensed non-polar hydrocarbons, which is dominated by a large amount of weakly polar compounds (such as light oxygenates), is moderate, the solubility of non-polar gases in a small amount of liquid is low. Therefore, the amount of CO2 and CO discharged from the cold gas phase is low, resulting in a lower purity of the recycled gas.

[0054] In hydroprocessing plants, a common method for gas stream purification is to use an amine scrubber, in which CO2 and H2S are reversibly captured in an aqueous amine solution. However, if the gas to be purified also contains water-soluble compounds such as methanol, ethanol and formic acid, these compounds are also captured by the amine scrubber, but the process is irreversible.

[0055] Gas purification using an amine scrubber involves very low pressure drops, so the scrubber can be connected in series with the recycle gas compressor, whose task is to pressurize the high-pressure gas to match the process pressure, compensating for the reactor pressure drop of perhaps 1 MPa.

[0056] BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A process layout with recirculation of unpurified wash water is shown.

[0058] Figure 2 Shown is a process layout with added fresh wash water

[0059] Figure 1

[0060] exist Figure 1 In the process, a feedstock (2) comprising oxygenates is pressurized by a feed pump (FP) and, after heating in a heat exchanger (HX) through a reactor effluent (10), is mixed with make-up hydrogen (4) pressurized in a make-up gas compressor (MUGC) and recycle gas (6) pressurized in a recycle gas compressor (COMP). The feed stream (8) is directed to a hydrodeoxygenation reactor (HDO) comprising one or more catalysts that provide the desired hydrodeoxygenation conversion of the reactor feed stream (8) by controlling conditions including composition, temperature, pressure and space velocity. Conditions may be selected to support only a limited degree of reaction, for example by limiting temperature, residence time or hydrogen availability. The reactor effluent (10) is cooled and the cooled reactor effluent (12) is fed to a hot high pressure separator (HHPS) to provide a first product stream (14) and a vapor stream (16). The vapor stream (16) is mixed with the wash water stream (18), and the mixed stream (20) is cooled in the cooler (C) and then fed to the three-phase separator (TPS) as a cold mixed stream (22), from which condensed acidic water (28), light products (24) and light gases (32) are separated, and the light gases (32) are fed to the recirculation compressor (COMP). A certain amount of the condensed acidic water (28) is pressurized by the recirculation pump (RP) and directed as wash water, while another certain amount (30) may be discharged from the system. The first product stream (14) and the light products (24) may be discharged as a mixed product stream (26).

[0061] In other embodiments, additional water may be added to the recycle wash water, and the method may include further steps including purification of the recycled light gas (32) and other hydroprocessing other than hydrodeoxygenation (HDO), such as olefin hydrogenation, hydrodearomatization, isomerization. These process steps may be in series with the hydrodeoxygenation step, or located in Figure 1 Upstream or downstream of the method shown.

[0062] In a further embodiment, the product stream (26) can be fed to a fractionation process to provide products for specific applications based on boiling point, such as naphtha for gasoline, naphtha for steam cracking, aviation fuel, road diesel or marine fuel. The product stream (26) or its fractions can also be fed to further hydroprocessing steps, including isomerization, hydrocracking and hydrodearomatization.

[0063] In further embodiments, the hydrogen-rich gas phase (32) may also be purified to increase the effective hydrogen pressure in the process.

[0064] Figure 2

[0065] exist Figure 2A comparative process is shown in . Here, a feedstock (2) comprising oxygenates is pressurized by a feed pump (FP) and, after heating in a heat exchanger (HX) through a reactor effluent (10), is mixed with make-up hydrogen (4) pressurized in a make-up gas compressor (MUGC) and recycle gas (6) pressurized in a recycle gas compressor (COMP). The feed stream (8) is fed to a hydrodeoxygenation reactor (HDO) which contains one or more catalysts which provide the desired hydrodeoxygenation conversion of the reactor feed stream (8) by controlling conditions including composition, temperature, pressure and space velocity. Conditions may be selected to support only a limited degree of reaction, for example by limiting temperature, residence time or hydrogen availability. The reactor effluent (10) is cooled and the cooled reactor effluent (12) is fed to a hot high pressure separator (HHPS) to provide a first product stream (14) and a vapor stream (16). The steam stream (16) is mixed with the fresh wash water stream (18), and the mixed stream (20) is cooled in a cooler (COOL) and then sent to a three-phase separator (TPS) as a cold mixed stream (22), from which condensed acidic water (30), light products (24) and light gases (32) are separated, and the light gases (32) are sent to a recycle compressor (COMP). In this process, all condensed acidic water (28) is discharged to the water treatment system of the equipment. The first product stream (14) and the light products (24) can be discharged as a mixed product stream (26). DETAILED DESCRIPTION

[0066] The first broad aspect of the present invention relates to a method for partially hydroprocessing a feedstock containing oxygen-containing compounds, comprising the following steps: introducing the feedstock, a certain amount of supplemental hydrogen and recycled gas into a catalytic hydrotreating method under conditions where 30-95% of the oxygen-containing compounds are converted into hydrocarbons to provide a partially hydroprocessed product stream; adding a certain amount of recycled wash water (containing at least 0.1 wt% of oxygen-containing compounds) to at least a certain amount of the hydroprocessed product stream (for example, a stream containing at least 50 wt% of the partially hydroprocessed product stream), optionally mixed with an additional amount of wash water, to provide a mixed hydroprocessed product stream; cooling and separating the mixed hydroprocessed product stream into a gas phase product fraction, a liquid aqueous fraction and a liquid product fraction; discharging a first amount of the liquid aqueous fraction as a waste stream; and directing at least a second amount of the liquid aqueous fraction as the recycled wash water amount.

[0067] This is associated with the advantage of minimizing the discharge of oxygenates in the wash water, since the wash water is at least partially saturated with oxygenates.The discharge of the first amount of said liquid aqueous fraction may be performed as a purge or by a purification process.

[0068] A second aspect relates to a method according to the first aspect, wherein the liquid aqueous fraction comprises at least 0.1 wt%, 0.2 wt% or 0.5 wt% of oxygen-containing compounds.

[0069] This has the associated advantage of providing a liquid aqueous fraction which will carry minimal amounts of oxygenates out of the process.

[0070] One aspect relates to a process according to the first aspect, wherein the liquid aqueous fraction comprises less than 20 wt%, 10 wt% or 5 wt% oxygenates, which results in a moderate amount of oxygenates bound in the liquid aqueous fraction.

[0071] A third aspect relates to a method according to the first or second aspect, wherein the liquid aqueous fraction comprises at least 50 ppm wt or 100ppm wt And less than 15wt% or 10wt% of inorganic salts.

[0072] This has the associated advantage that the process is capable of hydroprocessing feedstocks containing inorganic salts and recycling the wash water with salt recovery capability.

[0073] The fourth aspect relates to a method according to the first three aspects, wherein the ratio of the mass of wash water / the combined mass of (the hydroprocessed product stream + wash water) is greater than 1:50, 1:20 or 1:10, and less than 1:1, 1:2 or 1:5.

[0074] This has the associated advantage of balancing process convenience between low water levels relative to the partially hydroprocessed product stream and increased levels of removal of water soluble impurities such as salts.

[0075] A fifth aspect relates to the method according to the first four aspects, wherein a certain amount of the liquid aqueous fraction is directed to discharge.

[0076] This has the associated advantage of continuously removing a certain amount of impurities and product water from the process, while concentrating the purification of the effluent water in the process plant water treatment system.

[0077] A sixth aspect relates to the method according to the fifth aspect, wherein the portion of the liquid aqueous fraction directed for discharge is greater than 5%, 10% or 15%.

[0078] This has the associated advantage that high discharges correspond to processes where the net production of water is higher than the wash water requirement, which is typically the case for pyrolyzed biomass feedstocks having oxygen contents of 5%, 10% or even up to 50%.

[0079] At the same time, the amount directed to discharge must be limited, for example to less than 95% or 90%, in order to provide for the recycle of the remaining amount of the liquid aqueous fraction.

[0080] A seventh aspect relates to a process according to the fifth or sixth aspect, wherein the amount of the liquid aqueous fraction directed to discharge is less than 50%, 25% or 15%, which has the associated advantage that a moderate discharge corresponds to a process where the net production of water is less than the wash water requirement, which is typically the case when the biomass content in the pyrolysis feedstock is low and the oxygen content is less than 5%. The amount of the liquid aqueous fraction directed to discharge may be greater than 2%, 5% or 10% to ensure that salts and other impurities are removed from the process.

[0081] An eighth aspect relates to the method according to the fifth, sixth or seventh aspect, wherein the amount of the liquid aqueous fraction directed for discharge is separated into a brine or precipitate and an amount of purified water by using evaporation, membrane separation or precipitation.

[0082] This has the associated advantage of reducing the amount directed to wastewater.

[0083] A ninth aspect relates to a process apparatus configured to perform the method of any of the above aspects.

[0084] Example

[0085] To illustrate the advantages of the present disclosure, processes using pure make-up wash water and with recirculated wash water were studied.

[0086] The method studied is to partially hydroprocess the liquid feedstock produced by hydrothermal liquefaction of forest waste, with the aim of producing a fuel containing hydrocarbons and oxygenates (HC+Oxyg). The liquid feedstock contains a certain amount of chloride, which needs to be washed to remove the chloride in order to obtain a satisfactory product. The composition of the product stream of the hydroprocessing is shown in stream 12 in Table 1, which is then washed and separated into gas, acidic water and product. In Example 1, according to the present disclosure and Figure 1 Use recycled wash water, or in Example 2 according to Figure 2 For practical reporting purposes, the amounts of nitrogen and chloride are reported as NH3 and HCl, respectively, even though these substances exist in aqueous solution in ionic form, as NH4 + and Cl-.

[0087] The performance of Example 1 is shown in Table 1. It can be seen that by recycling the wash water, 896 kg / h of acidic water are still discharged from the process as effluent (stream 30), which contains about 1 kg / h of Cl. The heavy product stream (14) contains 1.9 kg / h of Cl, equivalent to 166 ppm Cl, and the light product stream (24) contains 3 g / h of HCl, equivalent to 2.4 ppm Cl. The effluent water (30) contains 1.1 kg / h (1232 ppm) of Cl and 145 kg / h of dissolved hydrocarbons and oxygenates. Due to the residual Cl, especially in the heavy product stream, it is necessary to send the product to a stripping column.

[0088] The corresponding performances for Example 2 are shown in Table 2. It can be seen that by recycling the wash water, 1312 kg / h of acidic water are discharged from the process as effluent (stream 30), which contains about 1.1 kg / h of Cl. The heavy product stream (14) contains 1.9 kg / h of Cl, equivalent to 166 ppm Cl, and the light product stream (24) contains 1 g / h HCl, equivalent to 1.0 ppm Cl. The effluent water (30) contains 1.1 kg / h (842 ppm) Cl and 160 kg / h of dissolved hydrocarbons and oxygenates. As in Example 1, the heavy product stream requires that the product be fed to a stripper.

[0089] Due to the presence of significant amounts of CO2 in the hydrogen-rich gas stream (32), both process arrangements will typically involve purification of this stream, for example by amine scrubbing.

[0090] From these data, it can be seen that the recycle of unpurified wash water results in reduced removal of water-soluble compounds, including Cl and oxygenate products. Washing with pure or purified wash water reduces the Cl concentration in the light product from 2.4 ppm Cl to 1.0 ppm Cl, but this difference is not significant due to the need for stripping of the heavy product. At the same time, washing with pure wash water discharges an additional 15 kg / h of product as dissolved oxygenates to waste.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

Claims

1. A method for partially hydroprocessing a feedstock containing oxygenates, the method comprising the following steps: a. directing the feedstock, an amount of make-up hydrogen and recycle gas to a catalytic hydrotreating process under conditions that convert 30-95% of the oxygenates to hydrocarbons to provide a partially hydroprocessed product stream; b. adding an amount of recycle wash water to a stream comprising at least 50 wt% of the partially hydroprocessed product stream to provide a mixed hydroprocessed product stream, the recycle wash water comprising at least 0.1 wt% oxygenates, optionally mixing it with an additional amount of wash water; c. cooling and separating the mixed hydroprocessed product stream into a gaseous product fraction, a liquid aqueous fraction and a liquid product fraction; d. discharging a first amount of said liquid aqueous fraction as a waste stream, and e. directing a second amount of said liquid aqueous fraction as said amount of recirculated wash water.

2. The process of claim 1, wherein the liquid aqueous fraction comprises at least 0.1 wt%, 0.2 wt% or 0.5 wt% and less than 20 wt%, 10 wt% or 5 wt% oxygen-containing compounds.

3. The process according to claim 1 or 2, wherein the liquid aqueous fraction contains at least 50 ppm wt or 100ppm wt And less than 15wt% or 10wt% of inorganic salts.

4. The process of claim 1 , 2 or 3, wherein the ratio of the mass of the wash water / the mass of the combination of the hydroprocessed product stream and the wash water is greater than 1 :50, 1 :20 or 1 :10, and less than 1 :1 , 1 :2 or 1 :

5.

5. A method according to claim 1, 2, 3 or 4, wherein a certain amount of the liquid aqueous fraction is directed to discharge.

6. A method according to claim 5, wherein the amount of liquid aqueous fraction directed for discharge is greater than 5%, 10% or 15% and less than 95% or 90% of the liquid aqueous fraction.

7. A method according to claim 5 or 6, wherein the amount of liquid aqueous fraction directed to discharge is greater than 2%, 5% or 10% and less than 50%, 25% or 15%.

8. The method according to claim 5, 6 or 7, wherein a certain amount of the liquid aqueous fraction directed to discharge is separated into a concentrated brine or precipitate, and a certain amount of purified water by using evaporation, membrane separation or precipitation.

9. A process equipment configured to perform the method according to any one of claims 1 to 8.

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