Removal of impurities in processes for the production of hydrocarbon products

Abstract

1. A method for producing a hydrocarbon product, comprising: i) a process for producing a hydrocarbon product; i) passing a feedstock derived from renewable and / or fossil resources through a hydroprocessing step to produce a main hydrotreated stream; said hydroprocessing step comprising: passing said feedstock through one or more catalytic hydrotreating units under a supply of hydrogen to produce a first hydrotreated stream; passing said first hydrotreated stream through a first separation step comprising the use of a separation unit to remove, inter alia, the impurities H2S, CO, CO2 and HO; taking an overhead stream from said first separation step and separating an overhead hydrocarbon liquid stream therefrom and passing it as a reflux stream to said first separation unit; taking a bottoms stream from said first separation step and passing at least a portion of said bottoms stream through a dewaxing step comprising the use of one or more catalytic hydrotreating units under a supply of hydrogen to produce said main hydrotreated stream; and ii) passing the main hydrotreated stream through a second separation step to produce said hydrocarbon products.

Description

[Technical Field]

[0001] The present invention relates to a method for producing hydrocarbons, in particular hydrocarbons boiling above 30°C, such as jet fuel, from a feedstock derived from renewable and / or fossil resources, preferably wherein the fossil resources represent a minor portion thereof, at most 30% by weight or less of the feedstock, for example at most 10% by weight. The method comprises passing the feedstock through a hydroprocessing step involving the use of one or more catalytic hydrotreating units, and a dewaxing step, whereby prior to the dewaxing step, a separation step significantly reduces the content of impurities, such as HS, HO, CO and CO (which may be harmful to the catalyst used in the dewaxing step). [Background technology]

[0002] There is growing interest in producing jet fuel or jet fuel and diesel from renewable feedstocks or by co-processing with conventional fossil fuel feedstocks. Specifically, when processing renewable feedstocks, oxygen in the feedstock is removed primarily as HO in hydroprocessing, resulting in a paraffinic fuel consisting of paraffins with the same number of carbon atoms as in the triglyceride backbone. This is called the hydrodeoxygenation (HDO) pathway. Oxygen can also be removed by the decarboxylation pathway, which produces CO instead of HO:

[0003] [ka] Some renewable resources also contain nitrogen, the removal of which also requires hydrogen, i.e., hydrodenitrogenation (HDN).

[0004] When producing hydrocarbon products, particularly jet fuel or jet and diesel oil, the feedstock is passed through a hydroprocessing step in a hydroprocessing section. This step typically involves HDO to obtain a hydrotreated stream, which is then passed through a first separation step, which usually involves the use of a separation unit, such as a high-pressure stripper (HP stripper), from which an overhead stream is removed. This overhead stream is partially condensed, and the resulting hydrocarbon liquid fraction is sent directly to a downstream dewaxing step in a hydroprocessing step or dewaxing section included in the hydroprocessing section, where hydroisomerization and, optionally, hydrocracking side reactions occur. After the dewaxing step, the hydrotreated stream is usually passed through another separation step to produce hydrocarbon products.

[0005] The dewaxing step uses precious metal catalysts, which are easily contaminated and thereby impaired by impurities, particularly H2S, carried over into the hydrocarbon liquid. Other impurities, such as H2O, NH3, CO, and CO2, may also be present. When operating with feedstock derived from fossil fuel sources, a high content of sulfur is present, and therefore hydroprocessing in the form of hydrodesulfurization (HDS) or hydrodenitrogenation (HDN) is usually performed. When operating with feedstock derived from renewable resources, the sulfur content is very low, and therefore hydroprocessing involves rather HDO and optionally also HDN treatment. As a result, the hydrotreated stream contains not only H2S but also H2O, NH3, CO, and CO2 as impurities, which need to be removed prior to the downstream dewaxing step.

[0006] EP2362892A1 (WO2010 / 053468A1) discloses the hydroprocessing of fuel feedstocks derived from biocomponent materials and the hydroprocessing of blends of biocomponent and mineral oil fuel feedstocks. More specifically, this cited document discloses a method for producing diesel fuel from a biocomponent feedstock, comprising hydrotreating the feedstock and subsequent catalytic dewaxing. The hydrotreated feedstock may be cascaded directly to the dewaxing step, or the hydrotreated feedstock may undergo intermediate separation in a separation unit, such as a fractionation column. There is no explicit or implicit disclosure of the use of reflux in the separation unit: the use of a fractionation column does not necessarily mean that it has reflux, and that is clearly not the purpose of this cited document. A reboiling column including a feed to the first stage and no recycle could easily be considered a fractionation column.

[0007] US2002 / 112990A1 (Patent Document 2) discloses a method for hydroprocessing fossil fuels in two or more hydroprocessing stages, in which the liquid and vapor products from the first stage are sent to a separation zone (S) where the liquid phase fraction is separated from the vapor phase fraction containing vaporized heavy hydrocarbon components. The vapor phase fraction is passed to a sorption zone (ST) in the presence of a sorbent (STA) where at least a portion of the heavy hydrocarbon components are removed. Both the liquid phase fraction and the sorbed heavy hydrocarbon components are sent to at least one additional hydroprocessing stage. Optionally, there is partial condensation and reflux in the sorption zone (ST) to remove high-boiling hydrocarbon components (heavy tail) from the vapor fraction. There is no stripping or reflux in the separation zone (S), therefore the impurities H2S, H2O, NH3, CO and CO2 in the bottom stream will go directly to the second hydroprocessing stage.

[0008] US2005 / 167334A1 (Patent Document 3) discloses hydrotreating fossil fuels, where the hydrotreating is hydrodesulfurization, hydrodenitrogenation, hydrodemetallization (to remove one or more metals such as vanadium, nickel, iron, sodium, titanium, silicon, copper, etc.), and hydrodearomatization. The hydroprocessing comprises at least two reaction steps, including reflux, with intermediate stripping of the effluent from the first step, each step being carried out with a hydrogen recycle loop limited to that step, thereby removing some of the H2S formed. The hydrotreating in the first reaction step does not contain HDO, and therefore the effluent does not contain additional impurities in the form of CO, CO2, in addition to HO. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] EP2362892A1(WO2010 / 053468A1) [Patent Document 2] US2002 / 112990A1 [Patent Document 3] US2005 / 167334A1 Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to significantly reduce the content of impurities H2S, H2O, NH3, CO and CO2 that may come into contact with the noble metal catalyst used in the dewaxing step. [Means for solving the problem]

[0011] This and other objects are solved by the present invention.

[0012] Accordingly, the present invention provides a method for producing a hydrocarbon product, comprising the steps of: i) a process for producing a hydrocarbon product; i) passing a feedstock derived from renewable and / or fossil resources through a hydroprocessing step to produce a main hydrotreated stream; said hydroprocessing step comprising: - passing said feedstock through one or more catalytic hydrotreating units under a supply of hydrogen to produce a first hydrotreated stream, e.g., a stream containing C1 to C30+ hydrocarbons, wherein said hydrotreated stream, i.e., the first hydrotreated stream, comprises the impurities H2S, NH3, CO, CO2, and HO; - passing the first hydrotreated stream through a first separation step involving the use of a separation unit to remove impurities; - removing an overhead stream from said first separation step, e.g., from said separation unit, separating an overhead hydrocarbon liquid stream therefrom and passing at least a portion thereof as a reflux stream to said first separation unit; - removing a bottom stream from said first separation step, e.g. from said separation unit; - passing at least a portion of said bottoms stream through a dewaxing step comprising the use of one or more catalytic hydrotreating units under a supply of hydrogen to produce said main hydrotreated stream; ii) passing the main hydrotreated stream through a second separation step to produce said hydrocarbon products; Including, the one or more catalytic hydrotreating units for producing said first hydrotreated stream comprise hydrodeoxygenation (HDO) and optionally also hydrodenitrogenation (HDN); The one or more catalytic hydrotreating units in the dewaxing step to produce the main hydrotreated stream include hydrodewaxing (HDW) in the presence of a noble metal catalyst, and optionally also hydrocracking (HCR); and the entire overhead hydrocarbon liquid stream (i.e., at least a portion of said overhead hydrocarbon liquid stream is the entire overhead hydrocarbon liquid stream) is passed as a reflux stream to the separation unit; The method is provided.

[0013] It will be appreciated that the impurities may be H2S, NH3, CO, CO2 and H2O, or a combination thereof. For example, the impurities may be CO and CO2.

[0014] The first hydrotreated stream from the catalytic hydrotreating unit usually contains such impurities, which can be harmful to the catalyst used in the subsequent dewaxing step. When operating in the so-called sweet mode, as in the present invention, the catalyst used in the catalytic hydrotreating unit of the dewaxing step (hydrodewaxing unit, HDW) is a noble metal catalyst that is sensitive to impurities, thereby making it necessary to use a first separation step, such as the use of a separation unit in the form of a high-pressure separator or column, to reduce the content of impurities.

[0015] In accordance with the present invention, instead of sending an overhead hydrocarbon liquid stream (e.g., from a separation unit) as part of the feed to the dewaxing step, this overhead hydrocarbon liquid stream is used as reflux to the separation unit. It has been found that impurities, particularly HO and HS, in the feed to the dewaxing step can be significantly reduced (e.g., by an order of magnitude), as shown in the examples below, thereby avoiding deterioration of the precious metal catalyst used therein.

[0016] The present invention is particularly useful when producing jet fuel, or jet fuel and diesel. When producing only diesel, the overhead stream from the separation unit in the first separation step, e.g., the HP stripper, usually completely bypasses the catalytic hydrotreating unit in the dewaxing step, so there is no need to protect it. In the end, it becomes a small portion of the total diesel product stream, so if it does not pass through the catalytic hydrotreating unit in the dewaxing step, it would be acceptable because this would not affect the overall diesel properties.

[0017] However, the overhead stream from the separation unit in the first separation step contains several jet-boiling range components. Therefore, when producing jet fuel, these components must undergo a dewaxing step to isomerize them. Otherwise, there is a risk of not reaching the jet fuel product specifications, particularly the jet fuel freezing point specifications. Therefore, according to the present invention, the overhead stream of the separation unit, e.g., the HP stripper overhead stream, is removed, partially condensed, for example, in an air cooler, and sent to a further (low-temperature) separator to remove a condensed hydrocarbon liquid stream, i.e., an overhead hydrocarbon liquid stream. While this stream would normally be sent directly as feed to the dewaxing step, the present invention instead uses it as reflux to the column, which surprisingly results in better overall impurity removal and, as a result, better protection of the catalytic hydrotreating unit(s) used in the dewaxing step.

[0018] In step ii), the main hydrotreated stream obtained from the dewaxing step is passed to a second separation step, which suitably involves the use of a separator, e.g., a cold separator, and a stripping section comprising a product stripper and a fractionator, e.g., a distillation column, thereby producing hydrocarbon products, in particular jet fuel, diesel and naphtha.

[0019] In one embodiment, step ii) comprises passing the main hydrotreated stream through a separator, preferably a low-temperature separator, to produce an aqueous stream (sour water stream), a hydrogen-rich stream, and a hydrocarbon stream (which is further separated into the hydrocarbon products in a subsequent stripping section); the hydrogen-rich stream is fed as a single recycle loop in the process by feeding it to one or more catalytic hydrotreating units to produce the first hydrotreated stream.

[0020] A single (common) recycle loop for hydrogen recycling is thereby provided, so that hydrogen-rich gas from the low-temperature separator can be fed, for example, to an HDO step prior to the first separation step, as well as optionally to a dewaxing step after the first separation step. Instead of separate recycle compressors and additional piping for independent supply of hydrogen to the HDO or dewaxing steps, a single hydrogen recycle compressor is required.

[0021] In one embodiment, the method further comprises feeding the hydrogen-rich stream to a dewaxing step comprising the use of one or more catalytic hydrotreating units to produce the main hydrotreated stream.

[0022] In another embodiment, the hydrogen-rich stream is not supplied to the dewaxing step. Instead, make-up hydrogen gas (e.g., from an external source) is supplied to the dewaxing step. After passing through the dewaxing step, the make-up hydrogen gas is preferably mixed with the hydrogen-rich stream (recycle gas) and then returned to the HDO step as a single recycle gas loop. In other words, according to this embodiment, the method further comprises: not supplying the hydrogen-rich stream to the dewaxing step; supplying make-up hydrogen gas (e.g., from an external source) to the dewaxing step; and, after passing through the dewaxing step, mixing it with the hydrogen-rich stream, thus producing a mixed hydrogen stream, which then serves as the single recycle loop. Using only make-up hydrogen gas is advantageous because, contrary to the hydrogen-rich stream, make-up hydrogen gas is essentially pure H and therefore does not contain contaminants.

[0023] In one embodiment, the method further comprises: separating an impurity-containing overhead gas stream from the overhead stream from the first separation step and passing the overhead gas stream through the separator in step ii), preferably after mixing it with the main hydrotreated stream, and preferably by subsequently cooling it, for example in an air cooler.

[0024] This allows impurities such as H2S and NH3 to be carried over and removed with the sour water stream removed from the separator, e.g., the low temperature separator, while simultaneously providing the single (common) recycle loop for recycling of hydrogen. In this way, further integration, simplicity and flexibility of the process is achieved.

[0025] In one embodiment, the hydrocarbon products boil above 30° C. and include one or more of the following: jet fuel, diesel, naphtha, and optionally also lube base stock. In a particular embodiment, the hydrocarbon is jet fuel, or jet fuel and diesel.

[0026] According to the present invention, the entire overhead hydrocarbon liquid stream of the first separation step (eg, from the separation unit) is passed to the separation unit as a reflux stream.

[0027] Thus, complete reflux is provided, i.e., the entire overhead hydrocarbon liquid stream is used. As used herein, the term "complete" means 95 wt. % or more, preferably 100 wt. % of the overhead hydrocarbon liquid stream. Thereby, there is complete reflux of the overhead hydrocarbon liquid stream, and the only feed to the dewaxing step comes from the bottom of the first separation step (e.g., from the separation unit), thus further increasing the removal of impurities, for example, by up to an order of magnitude or more for some impurities, more particularly HO and HS.

[0028] It will be appreciated that when there is complete reflux, the bottoms stream from the first separation step, and in particular the bottoms stream from the separation unit, is the stream that goes to the dewaxing step.

[0029] If there is no complete reflux but there is partial reflux, a purified first hydrotreated stream is optionally formed by combining the bottoms stream from the first separation step, particularly the bottoms stream from the separation unit, with the non-refluxed portion of the overhead liquid stream. The purified first hydrotreated stream is then passed to a dewaxing step. At least a portion of the bottoms stream from the first separation step, particularly the bottoms stream from the separation unit, and a portion of the non-refluxed overhead liquid stream may be passed to the dewaxing step individually, i.e., without combining these streams.

[0030] In one embodiment of the invention, the hydrocarbon products boil above 30°C and comprise one or more of the following: jet fuel, diesel, naphtha, and optionally also lubricating oil base stock. Suitably, the hydrocarbon products are jet fuel, or jet fuel and diesel.

[0031] In one embodiment of the present invention, in the first separation step, the separation unit is a high-pressure stripper (HP stripper), also called a HP stripping column.

[0032] HP strippers are well known in the art. They provide optimal removal of impurities. The stripping medium for an HP stripper can be make-up hydrogen gas, i.e., hydrogen-rich make-up gas, separator off-gas, e.g., hot separator off-gas, or nitrogen. The HP stripper may operate, for example, in a pressure range of 40 to 70 barg and a temperature range of 150 to 250°C.

[0033] In one embodiment, the first separation step further comprises using a high temperature separator upstream of the separation unit.

[0034] The liquid from the high temperature separator is sent to a downstream separation unit, such as an HP stripper, thereby increasing the flexibility and purification of the stripping step in the process.

[0035] As is well known in the art, high temperature separators are two or three phase vertical or horizontal separators, most commonly two phase, with a gas stream from the top and a liquid stream from the bottom, and operated at temperatures above 100°C, whereby water is removed as vapor in the gas stream. High temperature separators can be operated at high, medium or low pressures, for example in the range of 1 to 70 barg.

[0036] It will be understood that the term "hot separator" refers to when water is removed as a vapor, and the term "cold separator" refers to when water is removed as a liquid.

[0037] According to the present invention, at least a portion of said bottoms stream is passed to a dewaxing step. In one embodiment, in step i), a recycled oil stream is separated from said bottoms stream, e.g., the bottoms stream of the first separation step (from the high-pressure stripper), and passed upstream to one or more catalytic hydrotreating units, i.e., catalytic hydrotreating units to produce said first hydrotreated stream.

[0038] Recycled oil is used as a diluent to reduce the exothermicity of hydrotreating, especially due to the use of renewable feedstocks. Renewable feedstocks are more reactive than typical hydrocarbon feedstocks based on fossil fuels. Renewable feedstocks contain sulfur and, especially, more oxygen, and these reactions, which form HO and HS, respectively, are more exothermic. This allows for greater integration, flexibility, efficiency, and especially safety in the process.

[0039] In one embodiment, the one or more catalytic hydroprocessing units to produce the first hydrotreated stream are hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN).

[0040] As used herein, HDO also includes decarboxylation.

[0041] Catalytically active materials in hydroprocessing typically comprise an active metal (either a sulfide base metal such as nickel, cobalt, tungsten and / or molybdenum, but occasionally also an elemental noble metal such as platinum and / or palladium) and a refractory support (e.g., alumina, silica or titania, or a combination thereof).

[0042] Hydroprocessing conditions include temperatures in the interval 250-400°C, pressures in the interval 30-150 bar, and liquid hourly space velocities (LHSV) in the interval 0.1-2, optionally with intermediate cooling by quenching with cold hydrogen, feedstock, or product.

[0043] In one embodiment, the dewaxing step comprises using hydrodewaxing (HDW) in the presence of a noble metal catalyst, and optionally also using hydrocracking (HCR).

[0044] In the dewaxing step, the wax content is reduced by isomerization and optionally also cracking under isomerization conditions in the presence of hydrogen. Thus, as used herein, the term hydrodewaxing (HDW) is used interchangeably with the term hydroisomerization (HDI).

[0045] Catalytically active materials in hydrodewaxing typically include an active metal (either an elemental noble metal such as platinum and / or palladium), an acidic support (typically exhibiting high shape selectivity and capable of producing MOR, FER, MRE (more specifically MRE) *), molecular sieves having topologies such as MWW, AEL, TON, and MTT), and refractory supports (e.g., alumina, silica, or titania, or combinations thereof).

[0046] Isomerization (HDI) conditions include temperatures in the interval 250-400°C, pressures in the interval 20-100 bar, and liquid hourly space velocities (LHSV) in the interval 0.5-8, optionally with intermediate cooling by quenching with cold hydrogen, feedstock, or product.

[0047] The catalytically active material in hydrocracking is of similar nature to the catalytically active material in isomerization, which typically includes an active metal (either an elemental noble metal such as platinum and / or palladium, or a sulfide base metal such as nickel, cobalt, tungsten, and / or molybdenum), an acidic support (typically a molecular sieve with a topology such as MFI, BEA, or FAU, which exhibits high cracking activity), and a refractory support (e.g., alumina, silica, or titania, or a combination thereof). The difference from the catalytically active material in isomerization is typically the nature of the acidic support, which may be of a different structure (even amorphous silica-alumina) or have a different acidity (e.g., due to the silica:alumina ratio). It will be understood that in the context of the present invention, the nature of the metal may differ, for example, the metal for HDW may include a noble metal catalyst such as platinum, while the metal for hydrocracking may include a base metal such as nickel and / or molybdenum.

[0048] Hydrocracking conditions include temperatures in the interval 250-400°C, pressures in the interval 30-150 bar, and liquid hourly space velocities (LHSV) in the interval 0.5-8, optionally with intermediate cooling by quenching with cold hydrogen, feedstock, or product.

[0049] In one embodiment, the renewable resource derived feedstock is obtained from renewable resource raw materials, for example from plants, algae, animals, fish, vegetable oil refineries, household waste, plastic-rich waste, industrial organic waste such as tall oil or black liquor, or is a feedstock derived from one or more oxygenates selected from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols, wherein said oxygenates are derived from one or more of a biological source, a gasification process, a pyrolysis process, a Fischer-Tropsch synthesis or a methanol-based synthesis.

[0050] In one embodiment, the feedstock derived from a fossil fuel source is diesel, kerosene, naphtha, and vacuum gas oil (VGO).

[0051] Optionally, recycling of the hydrocarbon products produced in the process, such as the recycle oil stream in step i), is provided as part of the feedstock.

[0052] The present invention provides for the use of feedstock derived from renewable resources, or from fossil fuel sources, or a combination thereof, i.e., co-processing. In one embodiment, the feedstock is derived from renewable resources and from fossil resources, where the fossil resources represent a minor portion thereof, at most 30% by weight or less of the feedstock, for example at most 10% by weight.

[0053] 100% renewable feedstocks, i.e., feedstocks derived from renewable resources without co-feeding of feedstock from, for example, fossil fuel sources, or where the latter represents only a minor portion as described above, contain significantly less sulfur than pure fossil fuel feedstocks and require hydroprocessing, including HDO, to remove oxygen from the renewable feedstock, thus resulting in not only HS but also significantly higher concentrations of other impurities HO, NH, CO, and CO. [Brief explanation of the drawings]

[0054] [Figure 1] Figure 1 shows a schematic process and plant layout for producing naphtha, jet, and diesel from feedstocks according to the prior art, including an expanded view of the separation unit used in the first separation step. [Figure 2] Figure 2 shows a schematic process and plant layout for producing naphtha, jet, and diesel from a feedstock according to one embodiment of the present invention, including an expanded view of the separation unit used in the first separation step.

[0055] Referring specifically to Figure 1, a block flow diagram of an overall process / plant 10 is shown. A feedstock 12, e.g., derived from a renewable resource, is supplied to a hydroprocessing step or section 110. This step or section includes an optional feed step or section 112 and a reactor section including a catalytic hydrotreating unit 114, such as HDO, a dewaxing step or section 118, and a first separation step 116 (here illustrated by the use of separation unit 116 in the form of an HP stripper). From the hydroprocessing step 110, and particularly from the dewaxing step 118, a main hydrotreated stream 14 is produced, which is then passed to a second separation step 120, which produces an aqueous (water) stream 16; an off-gas stream 20 containing hydrocarbons, e.g., a light hydrocarbon stream, and also containing NH3, CO, CO2, and HS; and hydrocarbon products in the form of diesel 22, jet fuel 24, and naphtha 26.

[0056] After optionally passing the feedstock 12 through an optional feeding step 112, the feedstock 12′ passes through a catalytic hydrotreating unit 114, such as HDO, from which a first hydrotreated stream 12″ is removed. This stream then passes through an HP stripper 116, producing a vapor stream 46, i.e., an overhead gas stream containing most of the impurities, a bottoms stream 44 (from which a recycle oil stream 44′ and a stream 44″ are separated, and which is combined with the overhead liquid stream from the HP stripper 116 to form the purified first hydrotreated stream 12′″). The latter enters a dewaxing step 118, which involves the use of a catalytic hydrotreating unit, i.e., HDW unit 118, to produce the main hydrotreated stream 14. An additional catalytic hydrotreating unit in the form of a hydrocracking unit (HCR unit) may also be provided downstream or upstream of the HDO or HDW unit, for example to produce first hydrotreated stream 12'' or main hydrotreated stream 14, respectively.

[0057] The second separation step 120 involves the use of a separator 122, preferably a low-temperature separator, and a stripping section 124 including a product stripper and fractionator, e.g., a distillation column (not shown). The overhead gas stream 46 produced in the previous HP stripper 116 may be used, e.g., mixed, with the main hydrotreated stream 14 for the operation of the separator 122. A hydrogen-rich stream 18 is removed from the separator 122 and may be used as a hydrogen gas recycle, e.g., by mixing with streams 12' and 44' entering the catalytic hydrotreating unit 114. The separator 122 also produces the aforementioned water stream 16. Impurities are therefore carried over into the water stream 16 (sour water stream). The separator 122 produces a hydrocarbon stream 14', which is then fed to the stripping section 124 to produce a hydrocarbon-containing off-gas stream 20 and the hydrocarbon products diesel 22, jet fuel 24, and naphtha 26. Make-up hydrogen gas 40 , for example from an external battery limit, is fed to the HP stripper 116 and optionally also to the catalytic units 114 , 118 of the hydroprocessing step 110 .

[0058] An expanded schematic diagram of the HP stripper 116 is also provided in Figure 1. Stream 12" is fed, for example, to the first stage of the HP stripper 116. As shown in the figure, an HP stripper overhead stream is removed and partially condensed, for example, in an air cooler 116', and sent to separator 116" to remove a condensed hydrocarbon liquid stream, i.e., overhead hydrocarbon liquid stream 28, as well as sour water stream 30 and vapor stream 46. Overhead hydrocarbon liquid stream 28 is sent as feed to dewaxing step 118, optionally after being combined with bottoms stream 44" removed from the HP stripper 116. Makeup hydrogen gas 40 is used in stripping, and a recycle oil stream 44' is separated from the bottoms stream 44 of the HP stripper 116 and passed upstream to one or more catalytic hydrotreating units 114.

[0059] Referring now to FIG. 2, which illustrates an embodiment in accordance with the present invention, the block flow diagram of the overall process / plant 10 is identical to that of FIG. 1, except that stream 44″ separated from bottoms stream 44 from HP stripper 116 is the only hydrocarbon feed to dewaxing step 118.

[0060] An expanded schematic of the HP stripper 116 now shows the use of the overhead liquid stream 28 as reflux to the HP stripper instead. As shown here, the entire overhead hydrocarbon liquid stream 28 is passed as reflux, which surprisingly results in a significant improvement in overall impurity removal, resulting in better protection of the catalytic hydrotreating unit(s) in the dewaxing step 118.

[0061] From separator 122, preferably a low temperature separator, a hydrogen-rich stream 18 is removed which can be used as hydrogen gas recycle and which preferably serves as the single recycle loop in the process, i.e., hydrogen-rich stream 18 is fed to one or more catalytic hydrotreating units 114 to produce first hydrotreated stream 12. [Example]

[0062] example Prior art: According to FIG. 1, the levels of impurities in the liquid phase prior to heating to the dewaxing step or dewaxing section 18 are as follows: H2O: 1589wppb, NH3: 14wppb, H2S: 1528wppb, CO+CO2: 3798wppb.

[0063] The present invention: According to Figure 2, the entire overhead hydrocarbon liquid stream 28 is passed as reflux to the HP stripper 116, i.e., as complete reflux. The same operating conditions (pressure, temperature, stripping gas flow) in the HP stripper are used as for Figure 1. The impurity levels in the liquid phase before heating to the dewaxing step or dewaxing section 18 are now as follows: H2O: 136wppb, NH3: 9wppb, H2S: 124wppb, CO+CO2: 1197wppb.

[0064] Thereby, a surprisingly large reduction in the levels of impurities, in particular H2S, H2O and / or CO+CO2, is achieved. Approximately an order of magnitude reduction is obtained for H2S and H2O.

Claims

1. 1. A method for producing a hydrocarbon product, comprising: i) passing a feedstock derived from renewable and / or fossil resources through a hydroprocessing step to produce a main hydrotreated stream; wherein said hydroprocessing step comprises: - passing said feedstock through one or more catalytic hydrotreating units under a supply of hydrogen to produce a first hydrotreated stream, wherein said hydrotreated stream is free of impurities H ２ S., N.H. ３ , CO, CO ２ and H ２ Contains O; - passing the first hydrotreated stream through a first separation step involving the use of a separation unit to remove impurities; - removing an overhead stream from said first separation step, separating an overhead hydrocarbon liquid stream therefrom and passing at least a portion thereof as a reflux stream to said first separation unit; - removing a bottom stream from said first separation step; - passing at least a portion of said bottoms stream to a dewaxing step comprising the use of one or more catalytic hydrotreating units under a supply of hydrogen to produce said main hydrotreated stream; ii) passing the main hydrotreated stream to a second separation step to produce said hydrocarbon products; Including, the one or more catalytic hydroprocessing units for producing said first hydrotreated stream comprise hydrodeoxygenation (HDO) and optionally also hydrodenitrogenation (HDN); The one or more catalytic hydroprocessing units in the dewaxing step to produce the main hydrotreated stream include hydrodewaxing (HDW) in the presence of a noble metal catalyst, and optionally also hydrocracking (HCR); and passing the entire overhead hydrocarbon liquid stream as a reflux stream to said separation unit. The method.

2. 2. The method of claim 1, wherein step ii) comprises passing the main hydrotreated stream through a separator, preferably a low-temperature separator, to produce an aqueous stream (sour water stream), a hydrogen-rich stream, and a hydrocarbon stream which is further separated into the hydrocarbon products in a subsequent stripping section; and the hydrogen-rich stream is fed as a single recycle loop in the method by feeding it to the one or more catalytic hydrotreating units to produce the first hydrotreated stream.

3. Plus: not feeding a hydrogen-rich stream to the dewaxing step; feeding make-up hydrogen gas, e.g., make-up hydrogen gas from an external source, to the dewaxing step, which mixes with the hydrogen-rich stream after it has passed through the dewaxing step, thus producing a mixed hydrogen stream, which is then fed as said single recycle loop; The method of claim 2 , comprising:

4. Plus: separating an impurity-containing overhead gas stream from said overhead stream from the first separation step and passing said overhead gas stream through said separator in step ii), preferably after mixing it with said main hydrotreated stream, and preferably by subsequent cooling, for example in an air cooler; The method of claim 2 , comprising:

5. 5. The process of any one of claims 1 to 4, wherein the hydrocarbon products boil above 30°C and comprise one or more of jet fuel, diesel, naphtha, and optionally also lubricating oil base stocks.

6. 6. The method according to any one of claims 1 to 5, wherein in the first separation step the separation unit is a high-pressure stripper, preferably in the form of a stripping column using make-up hydrogen gas as the stripping medium and operated in the pressure range of 40 to 70 barg and the temperature range of 150 to 250°C.

7. 7. The method according to any one of claims 1 to 6, wherein the first separation step further comprises using a high temperature separator upstream of said separation unit, suitably in the form of a two- or three-phase, preferably two-phase, vertical or horizontal separator having a gas stream from the top and a liquid stream from the bottom and operating at a temperature above 100°C, whereby water is removed as vapor in said gas stream.

8. The method according to any one of claims 1 to 7, wherein in step i) a recycle oil stream is separated from said bottoms stream and passed upstream to said one or more catalytic hydrotreating units.

9. 9. The method of any one of claims 1 to 8, wherein the renewable resource derived feedstock is obtained from renewable resource raw materials, for example from plants, algae, animals, fish, vegetable oil refining, domestic waste, plastic rich waste, industrial organic waste such as tall oil or black liquor, or is a feedstock derived from one or more oxygenates selected from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols, wherein said oxygenates are derived from one or more of a biological source, a gasification process, a pyrolysis process, a Fischer-Tropsch synthesis or a methanol-based synthesis.

10. The method of any one of claims 1 to 9, wherein the feedstock derived from a fossil fuel source is selected from diesel, kerosene, naphtha and vacuum gas oil (VGO).

11. 11. The method of any one of claims 1 to 10, wherein the feedstock is derived from renewable and fossil resources, wherein the fossil resources represent a minor portion thereof, at most 30% by weight or less of the feedstock, for example at most 10% by weight.

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