RU2851016C1 - Method and installation for production of hydrocarbons with reduced co2 emissions and improved hydrogen integration - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: invention relates to a method for producing a hydrocarbon product. The method comprises the following steps: i) passing the feedstock obtained from a renewable source through a hydroprocessing stage to obtain a main stream subjected to hydrotreating; ii) directing the main stream subjected to hydrotreating to a separation stage to obtain: an aqueous stream, a hydrogen-enriched stream as a first recirculated gas stream, a waste gas stream containing hydrocarbons, and the specified hydrocarbon product boiling at a temperature above 50 °C; iii) directing the first recirculated gas stream to the hydroprocessing stage; iv) directing the waste gas stream as a second recirculated gas stream to the hydrogen production unit to produce a hydrogen stream as a feed hydrogen stream; v) directing the feed hydrogen stream to the hydroprocessing stage. Moreover, before carrying out stage iv), the specified waste gas stream is directed to the separation stage to remove H₂S, resulting in the specified second recycled gas stream. The invention also relates to a device.

EFFECT: invention minimises natural gas consumption in the hydrogen production unit, as well as the size of the steam reforming unit.

20 cl, 2 dwg, 1 tbl, 4 ex

Description

TECHNICAL FIELD OF THE PRESENT INVENTION

The present invention relates to a hydrotreating method and a plant for producing a hydrocarbon product boiling in the boiling range of transport fuels, in particular in any boiling range of diesel fuel, the boiling range of jet fuel and the boiling range of naphtha, by hydrotreating a feedstock originating from renewable sources, and which is combined, i.e. integrated with a hydrogen production unit, to generate at least part of the hydrogen required for said hydrotreating, thereby sharply reducing the consumption of hydrocarbons, in particular natural gas, used as feedstock and fuel in the hydrogen production unit, and also minimizing carbon dioxide emissions and plant costs.

PREREQUISITES FOR THE CREATION OF THE INVENTION

There is growing interest in producing diesel fuel, jet fuel, and naphtha from renewable feedstocks. These renewable feedstocks often contain high levels of oxygen compounds and unsaturated hydrocarbons. During hydrotreating of renewable feedstocks, oxygen is primarily removed as _H2O , yielding paraffinic fuels composed of paraffins with the same number of carbon atoms as the triglyceride backbone. This is called the hydrodeoxygenation (HDO) pathway. Oxygen can also be removed via the dicarboxylic pathway, which produces _CO2 instead of _H2O .

HDO pathway: C ₁₇ H ₃₄ COOH + 3.5 H ₂ ↔ C ₁₈ H ₃₈ + 2 H ₂ O

Dicarboxylic pathway: C ₁₇ H ₃₄ COOH + 0.5 H ₂ ↔ C ₁₇ H ₃₆ + CO ₂

In addition, there are some side effects

Water gas shift reaction: CO ₂ + H ₂ ↔ CO + H ₂ O

Methanation: CO + 3H ₂ ↔ CH ₄ + H ₂ O

Some renewable feedstocks also contain nitrogen. Hydrogen is also required to remove the nitrogen.

In general, hydrotreating renewable feedstocks (feedstocks rich in oxygenates, such as vegetable oils) requires large amounts of hydrogen gas. Producing such large quantities of hydrogen requires a very high demand for hydrocarbon feedstocks, i.e., natural gas, as feedstock and fuel. This also increases _CO2 emissions.

U.S. Patent 7,626,063 describes a method for converting vegetable oils and fats into hydrocarbon compounds boiling in the diesel fuel range, requiring a minimal amount of external hydrogen. Propane generated during the catalytic hydrotreating of vegetable oils and fats is used to generate at least 50% of the hydrogen required for catalytic refining. The hydrogen production step involves the use of a steam methane reforming unit and, if necessary, water gas shift.

U.S. Patent No. 10,011,785 describes an integrated process for producing hydrocarbons from renewable feedstocks that can reduce overall hydrogen consumption. In this process, a low-boiling component stream (containing hydrocarbons with 1-5 carbon atoms) generated during catalytic hydroprocessing of the feedstock is passed through an amine absorber to remove _CO2 and _H2S , and the resulting stream is separated into first and second recycle streams. The first recycle stream is sent to a catalytic hydroprocessing unit, and the second recycle stream is sent to a hydrogen production unit.

U.S. Patent No. 8,324,438 discloses a method for producing at least one mixed fuel from a paraffin-rich component and a cyclic compound-rich component, each of which is derived from a renewable feedstock. The method includes steam reforming to produce hydrogen using a separated overhead stream from a hot separator containing hydrogen and from which _CO2 and _H2S have been removed in a scrubber. A portion of the lighter materials from downstream fractionation is optionally sent to steam reforming.

Similarly, Canadian patent CA 2718509A1 describes a method for producing aviation fuel from renewable feedstocks, in which a _CO2- and _H2S -depleted overhead stream from a hot separator is combined with a hydrogen stream from a reforming zone. A portion of the lighter materials from downstream fractionation is sent to steam reforming, if necessary.

US Patent Application US 2012/151828 A1 describes a method involving the hydroprocessing of fats, oils, and waxes to produce low-carbon distillate fuels. The overhead stream from the separator is sent to a product recovery section, resulting in a _CO2 -rich fraction. A portion of the lighter materials (similar to liquefied petroleum gas (LPG)) from the downstream fractionation is optionally sent to a hydrogen production unit, thereby producing hydrogen for use in the process, optionally in conjunction with an external source of make-up hydrogen.

BRIEF DESCRIPTION OF THE INVENTION

It has been found that in addition to reducing overall hydrogen consumption, it is now also possible to integrate the renewable feedstock hydrotreating unit with the hydrogen production unit and minimize the energy consumption for the entire process/plant, primarily by minimizing the natural gas consumption to produce the hydrogen required for hydrotreating the renewable feedstock, thereby dramatically reducing the carbon dioxide emissions from the plant.

Accordingly, a first aspect of the invention provides a method for producing a hydrocarbon product, said method comprising the steps of:

i) directing the feedstock obtained from a renewable source through a hydrotreating step to produce a hydrotreated main stream;

Ii) directing the main hydrotreated stream to a separation stage to obtain:

water flow;

a hydrogen-rich stream as the first recycle gas stream;

a stream of exhaust gas containing hydrocarbons;

and the specified hydrocarbon product boiling at a temperature above 50°C;

iii) directing the first recycle gas stream to the hydroprocessing stage;

iv) directing the second recycle gas stream to a hydrogen production unit to produce a hydrogen stream as a make-up hydrogen stream;

v) directing the make-up hydrogen flow to the hydroprocessing stage;

wherein, prior to step iv), said off-gas stream is sent to a separation step, wherein the separation step is preferably at least one of an amine absorption step, an alkaline scrubber and a sulphur absorber for removing _H2S and thereby producing said second recycle gas stream.

It should be understood that for the purposes of this application, the hydrogen-enriched stream is also referred to as the first recycle gas stream. The hydrocarbon-containing off-gas stream is also referred to simply as the off-gas stream.

Thus, the obtained second recycle gas stream entering the hydrogen production unit contains light hydrocarbons, such as hydrocarbons having 1-4 carbon atoms, _H2 , _NH3 , CO and _CO2 , but does not contain _H2S or contains only an insignificant amount of _H2S . The off-gas stream and the second recycle stream obtained from it contain hydrogen not consumed in the hydrotreating unit(s) in the hydroprocessing stage in the form of soluble hydrogen in the hydrocarbon phase, and it is expedient to use it as part of the feedstock in the hydrogen production unit, which is described below.

Thus, the hydroprocessing and separation step for producing renewable hydrocarbon products is integrated with the hydrogen production unit into a common process or plant by utilizing at least two recycled streams, separately withdrawn from the separation step. This results in a significant reduction in energy consumption, particularly natural gas used as feedstock and fuel in the process, as will become apparent from the description and examples provided below. For example, according to the invention, a significant reduction in natural gas consumption in the range of 40-90% or more in the hydrogen production unit is achieved, while simultaneously enabling a smaller hydrogen production unit.

In one embodiment, the entire off-gas stream is sent to the separation stage. Consequently, the method and plant fully utilize this off-gas stream, thereby integrating it.

In one embodiment, the entire second recycle gas stream is sent to the hydrogen production unit. This results in lower consumption of, for example, natural gas, used as feedstock and fuel in the hydrogen production unit, compared to the case where only a portion of the second recycle stream is sent to the hydrogen production unit.

In one embodiment, said hydrogen-rich stream comprises 50% by volume of H ₂ or more, light hydrocarbons such as hydrocarbons having 1-4 carbon atoms, and optionally H ₂ S and NH ₃ , CO and CO ₂ .

According to the invention, said hydrogen-rich stream, i.e. the first recycle gas stream, is not subjected to a separation step for removing _H2S and/or _CO2 , and also, if necessary, for removing _NH3 and/or CO, before being sent to the hydrotreatment step, in particular before being sent to the first catalytic hydrotreating unit present therein. The first catalytic hydrotreating unit is suitable for hydrodeoxygenation, as will become apparent from the further description.

The first recycle gas stream is significantly larger, i.e. has a significantly higher flow rate, than the off-gas stream, so that according to the present invention, the need for providing a separation step such as an amine scrubber in the first recycle stream to remove _H2S and/or _CO2 is eliminated, often to remove _H2S and _CO2 , without any losses in the process, for example by using a nickel-molybdenum catalyst for hydrodeoxygenation, as in the applicant's co-pending patent application EP 20162755.1. Furthermore, renewable feedstocks such as vegetable oil, animal fat, etc. often have insufficient sulfur content compared to conventional fossil feedstocks. As a result, with traditional fossil feedstocks, an external sulfur-containing agent, such as dimethyl disulfide (DMDS) or another sulfur-containing agent, was typically added to ensure the minimum required amount of _H2S in the hydrogen-rich hydrodeoxygenation gas, thereby preserving the hydrotreating catalyst, such as hydrodeoxygenation, in a sulfided form. Therefore, the use of a high-pressure amine absorber allows for the removal of _H2S from the recycle gas before sending it back to hydroprocessing. This results in an increased amount of added external sulfur-containing agent and additional costs.

According to the invention, a separation stage, such as an amine scrubber, is provided in a much smaller off-gas stream and is designed to remove _H2S , thereby simplifying the process and reducing capital and operating costs, as well as reducing energy consumption by using a smaller separation stage in a smaller stream, i.e., the off-gas stream. More specifically, less amine, i.e., unloaded amine, is present; this condition thus leads to a smaller amine regeneration unit and less steam required for amine regeneration. Furthermore, the amine scrubber in the off-gas stream is a correspondingly low-pressure amine absorption system, which provides significantly lower capital and operating costs compared to high-pressure amine absorption systems typically used to clean the first recycle gas before sending it to hydrodeoxygenation.

Furthermore, although it is also possible to remove _CO2 from the off-gas stream, it is preferable not to remove _CO2 to avoid emitting _CO2 into the atmosphere, since the hydrogen production unit, i.e., the pre-reforming unit within it, can operate with a second recycle, which also contains _CO2 . This achieves a smaller carbon footprint. If necessary, an amine that is more selective for _H2S removal can be selected, with _CO2 removal being a by-product. Removing _H2S from the off-gas stream minimizes the need for sulfur adsorbent in the hydrogen production unit, particularly in the purification unit within it.

In one embodiment, said off-gas stream comprises light hydrocarbons in the form of hydrocarbons having 1-4 carbon atoms, _H2 , CO, _CO2 and also optionally _H2S .

In one embodiment, said hydrocarbon product boiling at a temperature above 50°C is a hydrocarbon product boiling in at least one of the following ranges: the diesel boiling range, the jet fuel boiling range, and the naphtha boiling range.

In one embodiment, the method further comprises: vi) separating said hydrogen-rich stream into said first recycle gas stream and a third recycle gas stream and directing said third recycle gas stream to said hydrogen production unit. This results in further integration. The third recycle gas stream is withdrawn as a purge stream, which, by directing it to the hydrogen production unit, allows for increasing the purity of the hydrogen circuit.

In one embodiment, in step i), the hydroprocessing step comprises:

i-1) directing the feedstock through a first catalytic hydrotreating unit with the addition of hydrogen to produce a first hydrotreated stream, preferably comprising hydrocarbons having 1-30 carbon atoms;

I-2) directing the first hydrotreated stream to a dewaxing section comprising a second catalytic hydrotreating unit with the addition of hydrogen to obtain said main hydrotreated stream.

In one embodiment, said first hydrotreated stream comprises hydrocarbons having 1-30 carbon atoms.

If necessary, the method includes the use of one or more additional catalytic hydrotreating units with the addition of hydrogen, such as a third catalytic hydrotreating unit or a cracking section. For example, it should be understood that when a hydrocarbon product boiling in the jet fuel range is desired, a hydrocracking unit is suitably employed, for example, before directing the resulting first hydrotreated stream to the dewaxing section.

In a particular embodiment, between steps i-1) and i-2), the method further comprises directing the first hydrotreated stream to a separator, such as a high or low pressure separator, for removing _H2S , _NH3 and _H2O , thereby obtaining said first hydrotreated stream and, if necessary, also obtaining a vapor stream and a recycle oil stream.

The first hydrotreated stream from the first catalytic hydrotreating unit typically contains impurities, particularly _H2S , _NH3 , CO, and _CO2 , which can be detrimental to the catalyst used in the subsequent dewaxing section. When the process operates in the so-called sulfur mode, the dewaxing section catalyst is a base metal catalyst that is tolerant of impurities, eliminating the need for a separator. When operating in the so-called sweet mode, the dewaxing section catalyst is a noble metal catalyst that is sensitive to impurities, requiring the use of a separator.

In one embodiment, in step ii) the separating step comprises:

ii-1) directing the hydrotreated main stream to a separator, preferably a cold separator, to obtain said aqueous stream, said hydrogen-rich stream, and a heavy hydrocarbon stream;

ii-2) directing the heavy hydrocarbon stream to a fractionation section, such as a stripping section, to obtain said off-gas stream and said hydrocarbon product, such as a hydrocarbon product boiling in at least one of the diesel boiling range, the jet fuel boiling range, and the naphtha boiling range.

In one embodiment, said heavy hydrocarbon stream comprises hydrocarbons having 5-30 carbon atoms, _H2 , CO and _CO2 .

In one embodiment, in step (v), the make-up hydrogen stream is directed to at least one of:

the said first catalytic hydrotreating unit;

said separator between stages i-1) and i-2), such as a high-pressure stripping column;

second catalytic hydrotreating unit;

and, if necessary, also an additional catalytic hydrotreating unit, such as a third catalytic hydrotreating unit.

In one embodiment, the first recycle stream is directed to a first catalytic hydrotreating unit.

It should be understood that the addition of hydrogen in step i), in particular in step i-1), i-2) and, if necessary, also in the intermediate step, i.e., directing the first hydrotreated stream to the separator for removing _H2S and _NH3 , occurs mainly from said makeup hydrogen stream and said first recycled stream. The present invention provides a high level of integration, so that there is no need to resort to the use of external makeup hydrogen, i.e., makeup hydrogen supplied from outside the method and the installation according to the present invention.

In one embodiment, the hydrogen production unit comprises feeding: said second stream of recycled gas and a hydrocarbon feedstock, such as natural gas, optionally together with one or more of said hydrocarbon products, such as naphtha and other light products, for example, "renewable naphtha" obtained in the process. The natural gas and, optionally, said naphtha, as well as the second recycled stream, are preferably fed separately to the hydrogen production unit. It is also envisaged that the naphtha and other light products recycled in this manner are used as the main portion or even the entire hydrocarbon feedstock. By including a portion of the hydrocarbon product, in particular renewable naphtha, as part of the hydrocarbon feedstock for the hydrogen production unit, an even greater reduction in energy consumption is achieved.

Hydrocarbon feedstock for the hydrogen production unit may also include LPG, biogas, methane, or combinations thereof.

It should also be understood that the said hydrocarbon products, i.e. the products produced in accordance with the method according to the invention, are so-called green products or renewable products, thus the diesel product is a renewable diesel fuel, the jet fuel is a renewable jet fuel, and the naphtha is a renewable naphtha.

In one embodiment, the hydrogen production unit includes subjecting a hydrocarbon feedstock to: purification in a purification unit, wherein said purification unit is preferably a sulfur-chlorine-metal absorption unit or a catalytic unit; optionally pre-reforming in a pre-reforming unit; catalytic steam reforming of methane in a steam reforming unit; water gas conversion in a water gas conversion unit; optionally removing carbon dioxide in a _CO2 separator unit; and purifying hydrogen in a hydrogen purification unit.

In a specific embodiment, said second recycle gas stream is sent to a purification unit. This is an efficient way to utilize available hydrogen in the process, as the sulfur-chlorine-metal absorption unit or catalytic unit typically requires the addition of hydrogen.

In one embodiment, the hydrogen-rich stream, or the first recycle stream, or the third recycle stream contains hydrogen in a concentration of 50% by volume or higher, preferably 70% by volume of hydrogen or higher, and any of said streams is directed through a hydrogen purification unit: before separating said hydrogen-rich stream into the first recycle stream or the third recycle stream, or before directing the first recycle stream to the hydroprocessing stage, or before directing said third recycle stream to the hydrogen production unit. Preferably, only the third recycle stream is directed to the hydrogen purification unit.

This allows the size of the steam reforming unit to be reduced, thereby minimizing the overall capital cost of the hydrogen production unit.

The hydrogen purification unit can be a unit with an _H2 membrane or a pressure swing adsorption (PSA) unit.

Although the above-mentioned hydrogen purification unit may be a specially adapted (separate) unit, in a particular embodiment, the hydrogen purification unit is a hydrogen purification unit of a hydrogen production unit, and said third recycled stream is directed through this hydrogen purification unit. This further facilitates the integration and increases the energy efficiency of the entire plant/process, i.e., the section comprising the hydroprocessing and separation stages, and the hydrogen production unit. In addition, it is more expedient to use an existing hydrogen purification unit of a hydrogen production unit, since it is generally expected that the requirement of this unit provides a hydrogen stream with an _H2 content of at least 99% by volume, whereas according to the present invention, a less stringent requirement for the purity of hydrogen is imposed, since this hydrogen is used in the hydroprocessing stage, in particular the first, second catalytic hydrotreating, as well as any additional catalytic hydrotreating, for example the third catalytic hydrotreating.

In another specific embodiment, the hydrogen purification unit is a pressure swing adsorption (PSA) unit, wherein said PSA unit produces an off-gas stream, i.e., PSA off-gas, which is used as fuel in the steam reforming unit of the hydrogen production unit, and/or in the fired heaters in any of the catalytic hydrotreating units of the hydroprocessing stage, the separation units of the separation stage, and/or for steam production. This allows for a further reduction in hydrocarbon consumption, thereby improving energy consumption, i.e., increasing energy efficiency, since the PSA off-gas, which would otherwise have to be flared, is advantageously used in the process.

In one embodiment, the steam reforming unit is: a convection reformer, preferably comprising one or more bayonet reforming tubes, such as an HTCR reformer, i.e., a Topsoe bayonet reformer, in which the heat for reforming is transferred by convection together with radiation; a tubular reformer, i.e., a conventional steam methane reformer (SMR), in which the heat for reforming is transferred mainly by radiation in a radiant furnace; an autothermal reformer (ATR), in which partial oxidation of hydrocarbon feedstock with oxygen and steam occurs, followed by catalytic reforming; an electrically heated steam methane reformer (e-SMR), in which electrical resistance is used to generate heat for catalytic reforming; or combinations thereof. In particular, e-SMR can use electricity from environmentally friendly sources, such as wind, hydropower and solar power, further minimizing carbon emissions.

For further information on these reforming units, details are provided in this application by direct reference to the applicant's patents and/or literature. For example, for tubular and autothermal reforming, an overview is provided in "Tubular reforming and autothermal reforming of natural gas - an overview of available processes" by Ib Dybkjær, Fuel Processing Technology 42 (1995) 85-107; and in European patent EP 0 535 505 for a description of HTCR. For a description of ATR and/or SMR for large-scale hydrogen production, see, for example, the article "Large-scale Hydrogen Production" by Jens R. Rostrup-Nielsen and Thomas Rostrup-Nielsen: https://www.topsoe.com/sites/default/files/topsoe_large_scale_hydrogen_produc.pdf.

A description of e-SMR, which is a newer technology, can be found in particular in international application WO 2019/228797 A1.

In one embodiment, the catalyst in the steam reforming unit is a reforming catalyst, such as a _nickel -based catalyst. In one embodiment _, the catalyst in the water gas shift reaction is any catalyst active in water gas shift reactions. The two catalysts may be the same _or different. Examples of reforming catalysts _are Ni/ _MgAl2O4 , Ni/ _{Al2O3 ,} Ni/ _CaAl2O4 , Ru/ _MgAl2O4 , _Rh / _MgAl2O4 , Ir/ _MgAl2O4 , _Mo2C , _Wo2C , _CeO2 , Ni/ _ZrO2 , _Ni / _MgAl2O3 , Ni/ _{CaAl2O3 ,} Ru/ _{MgAl2O3 .} , or Rh/MgAl ₂ O ₃ , a noble metal supported on Al ₂ O ₃ , but other catalysts suitable for reforming are also possible. The catalytically active material may be Ni, Ru, Rh, Ir, or a combination thereof, and the ceramic coating may be Al ₂ O ₃ , ZrO ₂ , MgAl ₂ O ₃ , CaAl ₂ O ₃ or a combination thereof, potentially mixed with oxides of Y, Ti, La, or Ce. The maximum reactor temperature may be between 850-1300°C. The feed gas pressure may be between 15-180 bar, preferably around 25 bar. The steam reforming catalyst is also referred to as a steam methane reforming catalyst or a methane reforming catalyst.

In one embodiment, before directing the make-up hydrogen stream to the hydroprocessing stage, the make-up hydrogen stream passes through a compressor section comprising a make-up compressor and, optionally, a recirculation compressor. The make-up compressor also produces a recirculated hydrogen stream, which is added to the hydrogen production unit, preferably directly to the second recirculated stream entering the hydrogen production unit, and/or to the purification unit of the hydrogen production unit. This provides even better integration, since there is no need for a separate or dedicated compressor for hydrogen recirculation in the hydrogen production unit, for example, for sulfur hydrogenation in the purification unit.

In a particular embodiment, before directing the first recycle stream to the hydroprocessing stage, the first recycle stream passes through said recycle compressor, i.e., a recycle compressor contained in the compressor section.

In one embodiment, the feedstock is obtained from raw materials of renewable origin, such as plants, algae, animals, fish, vegetable oil processing products, municipal waste, plastic-rich waste, industrial organic waste such as tall oil or black liquor, or a feedstock obtained from one or more oxygen-containing compounds taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols, wherein said oxygen-containing compounds originate from one or more biological sources, a gasification process, a pyrolysis process, a Fischer-Tropsch synthesis or a methanol-based synthesis. The oxygen-containing compounds may also originate from other synthesis processes. Some of these feedstocks may contain aromatic hydrocarbons, in particular products of pyrolysis processes or waste such as frying oil. Any combinations of the above-mentioned feedstocks are also contemplated.

In another embodiment, step i) may also include the addition of a feedstock derived from a fossil fuel source, such as diesel, kerosene, naphtha, and vacuum gas oil (VGO), or a processed hydrocarbon product. This additional feedstock acts as a hydrocarbon diluent, thereby absorbing the heat of exothermic reactions in the catalytic hydrotreating unit(s) in the hydroprocessing step.

In one embodiment, the first catalytic hydrotreating unit is hydrodeoxygenation (HDO), i.e. HDO is carried out in the HDO unit, the second catalytic hydrotreating unit is hydrodewaxing (HDW), and the additional catalytic hydrotreating unit, such as the third catalytic hydrotreating unit, is hydrocracking (HCR).

The material is catalytically active in hydrotreating and comprises an active metal (sulfided base metals such as nickel, cobalt, tungsten and/or molybdenum, but possibly also elemental noble metals such as platinum and/or palladium) and a refractory support (such as alumina, silica or titanium dioxide, or combinations thereof).

Hydrotreating conditions include temperatures in the range of 250-400°C, pressures in the range of 30-150 bar and liquid hourly space velocities (LHSV) in the range of 0.1-2, optionally with intermediate cooling by flash cooling with cold hydrogen, feedstock or product.

The material catalytically active in hydrodewaxing typically includes an active metal (either elemental noble metals such as platinum and/or palladium, or sulfided base metals such as nickel, cobalt, tungsten, and/or molybdenum), an acidic support (usually molecular sieves exhibiting high shape selectivity and having a topology such as MOR, FER, MRE, MWW, AEL, TON, and MTT), and a refractory support (such as alumina, silica, or titanium dioxide, or combinations thereof).

Isomerization conditions include temperature in the range of 250-400°C, pressure in the range of 20-100 bar and liquid hourly space velocity (LHSV) in the range of 0.5-8.

A material catalytically active in hydrocracking is similar in nature to a material catalytically active in isomerization and typically comprises an active metal (either elemental noble metals such as platinum and/or palladium, or sulfided base metals such as nickel, cobalt, tungsten, and/or molybdenum), an acidic support (usually molecular sieves exhibiting high shape selectivity and having a topology such as MOR, FER, MRE, MWW, MFI, BEA, and FAU), and a refractory support (such as alumina, silica, or titania, or combinations thereof). The difference with a material catalytically active in isomerization typically lies in the nature of the acidic support, which may have a different structure (even amorphous aluminosilicate) or have a different acidity, for example, due to the silica:alumina ratio.

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

Other types of hydrotreating, such as hydrodearomatization (HDA), are also envisaged. The material catalytically active in hydrodearomatization typically comprises an active metal (usually elemental noble metals such as platinum and/or palladium, but possibly also sulfided base metals such as nickel, cobalt, tungsten, and/or molybdenum) and a refractory support (e.g., amorphous aluminosilicate, alumina, silicon dioxide, or titanium dioxide, or combinations thereof).

Hydrodearomatization conditions include temperature in the range of 200-350°C, pressure in the range of 20-100 bar and liquid hourly space velocity (LHSV) in the range of 0.5-8.

In a second aspect, the invention also encompasses the processing of feedstock obtained from a fossil fuel source.

Accordingly, a method for producing a hydrocarbon product is also provided, said method comprising the steps of:

i) directing a feedstock obtained from a fossil fuel source through a hydrotreating step to produce a hydrotreated main stream;

ii) directing the main hydrotreated stream to a separation stage to obtain:

if water flow is required,

hydrogen-rich stream as the first recycle gas stream,

a stream of exhaust gas containing hydrocarbons,

and the specified hydrocarbon product boiling at a temperature above 50°C;

iii) directing the first recycle gas stream to the hydroprocessing stage;

iv) directing the off-gas stream as a second recycle gas stream to a hydrogen production unit to produce a hydrogen stream as a make-up hydrogen stream;

v) directing the make-up hydrogen flow to the hydroprocessing stage;

wherein, prior to step iv), said off-gas stream is sent to a separation step, wherein the separation step is preferably at least one of an amine absorption step, an alkaline scrubber and a sulphur absorber for removing _H2S and thereby producing said second recycle gas stream.

In one embodiment of the second aspect of the invention, the feedstock originating from a fossil fuel source is diesel fuel, kerosene, naphtha, and vacuum gas oil (VGO).

In another embodiment of the second aspect of the invention, step i) may also comprise adding a feedstock originating from a renewable source as specified in accordance with the first aspect of the invention.

In a third aspect, the invention is an installation, i.e. a process installation for the production of a hydrocarbon product, comprising:

- a hydroprocessing section designed to receive feedstock obtained from a renewable source and a compressed stream enriched with hydrogen to produce a main stream subjected to hydrotreatment;

- a separation section designed to receive said main stream subjected to hydrotreatment to obtain an aqueous stream, a hydrogen-enriched stream as a first recycle gas stream, a hydrocarbon-containing off-gas stream as a second recycle stream, and said hydrocarbon product boiling at a temperature above 50°C;

- a separation section, which preferably comprises at least one of an amine absorption stage, an alkaline scrubber and a sulphur absorber, designed to receive said off-gas stream for removing _H2S and thus producing said second recycle gas stream;

- a hydrogen production unit (HPU) designed to receive said second stream of recycled gas and hydrocarbon feedstock to produce a make-up hydrogen stream;

- a compressor section designed to receive said first recycled gas stream and at least a portion of the makeup hydrogen stream obtained in said HPU to generate said compressed hydrogen-enriched feed stream and a recycled makeup hydrogen stream;

- a pipeline for directing said first flow of recirculated gas to said compressor section;

- a pipeline for directing the specified flow of make-up hydrogen from the HPU to the specified compressor section;

- if necessary, a pipeline for recirculating the said recirculated make-up hydrogen flow into the HPU.

- if necessary, means for separating said hydrogen-enriched stream into said first recirculated gas stream and a third recirculated gas stream and a pipeline for directing said third recirculated gas stream to said HPU.

Any of the above-mentioned embodiments of the first aspect of the invention may be used together with the second and third aspects of the present invention. It should be understood that any of the corresponding advantages of the above-mentioned embodiments of the first aspect of the invention may also be used together with the second and third aspects of the present invention.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 shows a flow chart of the entire method/installation, i.e., an integrated method/installation according to a specific embodiment of the invention.

Fig. 2 shows a flow chart of the entire method/installation according to another specific embodiment of the invention.

Detailed description

Fig. 1 shows a process flow diagram of the entire method/installation 10, where a renewable feedstock 12, such as soybean oil, rapeseed oil or waste edible oil, is fed to a hydroprocessing stage 110. This stage or section includes a feed section and a reactor section including HDO, HDW units and, if necessary, also HCR (hydrocracking) units, to produce a main hydrotreated stream 14, which is then fed to a separation stage 120, which produces: an aqueous stream (water) 16; a hydrogen-rich stream 18, preferably containing 50% by volume of H ₂ or more, light hydrocarbons, H ₂ S, CO and CO ₂ ; an off-gas stream 20 containing hydrocarbons, such as a light hydrocarbon stream also containing _NH3 , CO, _CO2 and _H2S and, if necessary, also hydrogen not consumed in the hydrotreating unit(s) in the form of dissolved hydrogen in the hydrocarbon phase; and hydrocarbon products in the form of renewable diesel fuel 22, renewable jet fuel 24 and renewable naphtha 26. The hydrogen-rich stream 18 is separated to form a first recycle stream 28, and the off-gas stream 20 is passed to the H ₂ S removal stage 130 to form a treated off-gas stream in the form of a second recycle stream 32, which is then used as feedstock for the hydrogen production unit 140 together with the produced renewable product, for example, renewable naphtha 26. The third recycle gas stream 30 is formed by separating the hydrogen-rich stream 18. The first recycle stream 28, sent to the hydroprocessing stage 110, does not include the use of a separation section for removing H ₂ S and/or carbon oxides (CO, CO ₂ ).

The hydrogen production unit 140 includes a first section 142 that includes a purification unit, such as a sulfur-chlorine-metal absorption unit or a catalytic unit, one or more pre-reforming units, a steam reforming unit, preferably a convection reforming unit (HTCR), and water gas conversion unit(s), as is well known in the hydrogen production art; none of these units are shown here. A hydrogen purification unit, such as a PSA unit 144, is provided for further enrichment of the gas and for producing a make-up hydrogen stream 36. This PSA unit is also used to purify the third recycle gas stream 30. The off-gas 38 from the PSA unit (PSA off-gas) is used as fuel in the hydrogen production unit and, in particular, as fuel for the HTCR unit, in particular the burner of the HTCR unit, as well as in the hydroprocessing stage 110. The hydrocarbon feedstock in the form of a natural gas stream 34 is used as make-up gas for steam reforming in the hydrogen production unit 140, 142.

The first recycle gas stream 28 enters the compressor section 150, which includes a recycle compressor and a makeup gas compressor, not shown. The first recycle gas stream 28 and the makeup hydrogen stream 36 are then compressed, respectively, by the recycle compressor and the makeup compressor and are used to add hydrogen in the form of stream 40 to the hydroprocessing stage 110. From the makeup compressor, the hydrogen stream 42 is recycled to the hydrogen production unit 140, 142.

In Fig. 2, another specific embodiment of the invention is shown, showing specific details of various sections, in particular, the hydroprocessing stage 110 and the separation stage 120 of Fig. 1. Renewable feedstock 12 enters the feed section 112 of the hydroprocessing stage 110, where it is mixed with a hydrogen stream 40' from a recycle compressor 152, as well as recycle oil 44 from a high-pressure separator 116, such as a high-pressure (HP) stripper, located downstream. The resulting renewable feedstock 12' is fed to a first catalytic hydrotreating unit, in this case an HDO unit 114, from which a first hydrotreated stream 12" is withdrawn. This stream is then sent to the aforementioned high-pressure separator 116 to form a vapor stream 46, a recycle oil stream 44, and a liquid stream 12"'. The latter enters the dewaxing stage 118, which includes a second catalytic hydrotreating unit, in this case the HDW unit 118, to produce the main hydrotreated stream 14. A third catalytic hydrotreating unit in the form of a hydrocracking unit (HCR unit) may also be provided, for example downstream of the HDO or HDW units, to produce the main hydrotreated stream 14. Such a hydrocracking unit may also be provided upstream of the HDO unit, processing the recycled heavy product stream in a so-called reverse sequence process scheme. The PSA off-gas stream 38 from the hydrogen production unit 140 can be expediently used as fuel in the dewaxing stage 118.

The main hydrotreated stream 14 may then be mixed with a wash water stream 16'' which is separated from the aqueous stream 16 obtained in the downstream separation step 120. The separation step 120 includes the use of a separator 122, preferably a cold separator, and a subsequent stripping section 124. The vapor 46 formed in the preceding high-pressure separator 116 is used to operate the separator 122. From the separator 122, a hydrogen-rich stream 18 is withdrawn as a first stream of hydrogen-rich recycle gas, as well as the aforementioned aqueous stream 16, which is then separated into a sour water stream 16' and a wash water stream 16''. From the separator 122, a heavy hydrocarbon stream 14' is obtained, preferably containing hydrocarbons having 5-30 carbon atoms, _H2 , _H2S , CO and _CO2 , which is then fed to the stripping section 124 to obtain an off-gas stream 20 containing hydrocarbons, as well as renewable diesel fuel 22 and renewable naphtha 26 as hydrocarbon products.

The hydrogen production unit 140 includes, as shown in Fig. 1, a hydrogen purification unit, preferably a PSA unit (not shown), in which an off-gas stream 38 is generated containing _CH4 , _H2 , CO and _CO2 , and which is used as fuel in the method, and not only in the hydrogen production unit itself, i.e. for the steam reforming unit, in particular the HTCR unit, but also in the hydroprocessing stage, in particular, as shown here, in the dewaxing section 118 of this stage. Accordingly, there is no need to subject the excess PSA off-gas not used in the hydrogen production unit to burnout or to flaring.

The make-up hydrogen stream 36 is sent to the make-up compressor 154 of the compressor section 150. The compressed hydrogen stream 42 is recycled to the hydrogen production unit 140, as well as to the hydroprocessing stage, in particular for the operation of the high-pressure separator 116, the HDW unit of the dewaxing section 118 and, if necessary, also the HDO unit 114, as the compressed hydrogen stream 40. The first recycle gas stream 28, preferably containing 50% by weight or more of hydrogen, is sent to the recirculation compressor 152 of the compressor section 150, thereby obtaining another compressed hydrogen stream 40', which is used in the hydroprocessing stage, in particular for the operation of the HDO unit 114.

The third recycle gas stream 30, also preferably containing 50% by weight or more of hydrogen, as well as hydrocarbons, is purified in a hydrogen purification unit, which may be located separately from the hydrogen production unit. However, Figs. 1 and 2 show a preferred embodiment in which a hydrogen purification unit, preferably a PSA unit, already part of the hydrogen production unit, is also used to enrich the third recycle gas stream 30 with hydrogen, thereby further improving the integration of the entire method/plant.

The off-gas stream 20 is processed in the _H2S removal unit 130, preferably in a low-pressure amine absorber, to form a processed off-gas stream as a second recycle gas stream 32, which is used, for example, as a feedstock together with the renewable naphtha 26 and the recycled hydrogen 42 in the hydrogen production unit 140.

Examples

Example 1 :

To produce renewable diesel fuel, the process flow diagram shown in Fig. 2 was used, but without the use of separator 116, for example, the so-called HydroFlex™ high-sulfur mode. For hydrogen production, an HTCR unit was used in conjunction with a PSA unit for hydrogen purification, as well as pre-reforming and water gas shift. 100 kg/hour of renewable feedstock was used.

In the HydroFlexTM high-sulfur mode, acid gases ( _H2S and _NH3 ) are not removed during the hydroprocessing stage of the process. The renewable feedstock, along with hydrogen, is processed in the HDO unit and then in the dewaxing unit (DW unit) to produce, for example, renewable diesel fuel and renewable jet fuel. The following run shows the start of the cycle with fresh catalyst and the end of the cycle with a catalyst close to its commercial life.

Soybean oil is used as the renewable feedstock. Thus, the feed rate to the hydroprocessing reactor (HDO as the hydrotreating unit) is 100 kg/h. The make-up hydrogen gas flow rate from the hydrogen production unit is 3.1 kg/h (SOR, cycle start) and 3.8 kg/h (EOR, cycle end). The exit gas velocity (purge gas velocity from the separation stage), i.e. the first light hydrocarbon stream (the first recycle gas stream 18 in the figure), is 0.0 kg/h (SOR), 1.4 kg/h (EOR), and the exit gas velocity, i.e. the second light hydrocarbon stream (stream 20), is 7.2 kg/h (SOR), 8.0 kg/h (EOR). The natural gas (NG) requirement (stream 34) for the hydrogen production unit is 3.87 kg/h (SOR), 3.38 kg/h (EOR).

The percentage reduction in natural gas consumption compared to a non-integrated unit providing the same hydrogen demand for hydrotreating is 63% (SOR) and 73% (EOR). This represents a savings of approximately 6-7% in the steam reforming (HTCR) unit compared to the 100% natural gas case, i.e., using a non-integrated hydrogen production unit based on 100% natural gas.

Example 2 :

To produce renewable diesel fuel, the process flow diagram shown in Fig. 2 was used, with acid gas removal during the hydroprocessing stage, such as the so-called HydroFlex™ low-sulfur mode. Hydrogen production utilized an HTCR unit combined with a PSA unit for hydrogen purification, as well as pre-reforming and water gas shift. A renewable feedstock rate of 100 kg/hour was used.

In the HydroFlex™ low-sulfur mode, acid gases ( _H2S and _NH3 ) are removed in the hydroprocessing stage 110 of the process, for example, in the separator 116 of this stage. The renewable feedstock, together with hydrogen, is processed in the HDO unit, followed by the removal of _H2S and _NH3 and then processed in the dewaxing unit (HDW unit) to subsequently produce, for example, renewable diesel fuel.

Rapeseed oil is used as the renewable feedstock. The feed rate to the hydroprocessing reactor is 100 kg/h. The make-up hydrogen gas flow rate from the hydrogen production unit is 4.79 kg/h (SOR) and 4.84 kg/h (EOR). The outlet gas (purge gas) flow rate from the separation stage, i.e., the first stream of light hydrocarbons, is 2.5 kg/h (SOR), 2.9 kg/h (EOR), and the off-gas flow rate, i.e., the second stream of light hydrocarbons, is 5.0 kg/h (SOR), 5.8 kg/h (EOR). Thus, the NG requirement is 8.37 kg/h (SOR) and 7.34 kg/h (EOR).

The percentage reduction in NG consumption compared to a non-integrated unit providing the same hydrogen demand for hydrotreating is 45% (SOR) and 52% (EOR). This also results in a reduction in the size of the steam reforming (HTCR) unit by approximately 11% compared to the 100% NG unit.

Example 3 :

As in Example 2, a HydroFlex™ low-sulfur unit was used, but this time for the production of renewable jet fuel. Hydrogen production utilized an HTCR unit, along with a PSA unit for hydrogen purification, as well as pre-reforming and water-gas shift.

Edible oil is used as a renewable feedstock. The feed rate to the hydroprocessing reactor is 100 kg/h. The make-up hydrogen gas flow rate from the hydrogen production unit is 4.79 kg/h (SOR) and 4.84 kg/h (EOR). The outlet gas (purge gas) velocity is 0.0 kg/h (SOR), 1.37 kg/h (EOR), and the off-gas velocity is 11.58 kg/h (SOR), 12.72 kg/h (EOR). Thus, the NG requirement is 2.6 kg/h (SOR), 0.20 kg/h (EOR).

The percentage reduction in NG consumption compared to a non-integrated unit providing the same hydrotreating hydrogen requirement is 84% (SOR), 98% (EOR), with approximately 10% HTCR size savings compared to the 100% NG case.

Thus, these examples demonstrate significant reductions in NG consumption in the range of 40-90% or more, while still providing a smaller hydrogen production unit size.

_CO2 emissions are also reduced dramatically. For example, by reducing natural gas consumption by approximately 70% _{, CO2} emissions ( ^Nm3 /1000 ^Nm3H2 ) are also reduced by approximately 70%, as are operating costs (cost reduction of approximately 70%). Furthermore, capital costs are reduced by approximately 10%.

Example 4 :

This example demonstrates some of the benefits of _H2S removal using amine scrubbing in the off-gas stream only. The calculation is based on a feed rate of 100 kg/hour, as in the previous examples. The percentage savings in steam are the same as the percentage savings in regenerated amines, since they are proportional. The table below shows the results.

Amine consumption, kg/h Example High pressure absorber for all recycled gas to hydroprocessing
(as used in the prior art) Used exhaust gas cleaning
HydroFlex™
(according to the invention) Saving steam during amine regeneration by using amine only for exhaust gas cleaning. Saving regenerated amine HydroFlex™ High Sulfur Unit 92.4 26.9 71% 71% HydroFlex™ Low Sulfur Unit 86.5 27.7 68% 68% HydroFlex™ High Sulfur Jet Fuel Unit 209.9 31.5 85% 85%

The invention is further described by the following points (implementation variants).

1. A method for producing a hydrocarbon product, said method comprising the following stages:

i) directing the feedstock obtained from a renewable source through a hydrotreating step to produce a hydrotreated main stream;

ii) directing the main hydrotreated stream to a separation stage to obtain:

water flow,

hydrogen-rich stream as the first recycle gas stream,

a stream of exhaust gas containing hydrocarbons,

and the specified hydrocarbon product boiling at a temperature above 50°C;

iii) directing the first recycle gas stream to the hydroprocessing stage;

iv) directing the off-gas stream as a second recycle gas stream to a hydrogen production unit to produce a hydrogen stream as a make-up hydrogen stream;

v) directing the make-up hydrogen flow to the hydroprocessing stage;

wherein, prior to step iv), said off-gas stream is sent to a separation step, wherein the separation step is preferably at least one of an amine absorption step, an alkaline scrubber and a sulphur absorber for removing _H2S and thereby producing said second recycle gas stream.

2. The method according to paragraph 1, wherein the entire flow of exhaust gas is directed to the separation stage.

3. The method according to any one of paragraphs 1, 2, wherein the entire second flow of recirculated gas is sent to the hydrogen production unit.

4. The method according to any one of claims 1 to 3, wherein the method further comprises: vi) separating said hydrogen-rich stream into said first recycle gas stream and a third recycle gas stream and directing said third recycle gas stream to said hydrogen production unit.

5. The method according to any one of paragraphs 1-4, wherein in step i) the hydroprocessing step comprises:

i-1) directing the feedstock through a first catalytic hydrotreating unit while adding hydrogen to produce a first hydrotreated stream;

i-2) directing the first hydrotreated stream to a dewaxing section comprising a second catalytic hydrotreating unit with the addition of hydrogen to obtain said main hydrotreated stream.

6. The method according to any one of claims 1-5, wherein between steps i-1) and i-2) the method further comprises directing the first hydrotreated stream to a separator, such as a high or low pressure separator, for removing _H2S , _NH3 and _H2O , thereby obtaining said first hydrotreated stream and, if necessary, also obtaining a vapor stream and a recycle oil stream.

7. The method according to any one of claims 1 to 6, wherein in step ii) the separation step comprises:

ii-1) directing the hydrotreated main stream to a separator, preferably a cold separator, to obtain said aqueous stream, said hydrogen-rich stream, and a heavy hydrocarbon stream;

ii-2) directing the flow of heavy hydrocarbons to a fractionation section to obtain said exhaust gas flow and said hydrocarbon product.

8. The method according to any one of paragraphs 1-7, wherein in step v) the make-up hydrogen flow is directed to at least one of:

the said first catalytic hydrotreating unit;

said separator between stages i-1) and i-2), such as a high-pressure stripping column;

second catalytic hydrotreating unit;

and, if necessary, also an additional catalytic hydrotreating unit, such as a third catalytic hydrotreating unit.

9. The method according to any one of claims 1-8, wherein the first recycle gas stream is directed to the first catalytic hydrotreating unit.

10. The method of claim 8, wherein the first recycle gas stream is not subjected to a separation step to remove H ₂ S and/or CO ₂ , and optionally to remove NH ₃ and/or CO, before being sent to the first catalytic hydrotreating unit.

11. The method according to any one of claims 1 to 10, wherein the hydrogen production unit comprises feeding as feedstock: said second recycle gas stream and a hydrocarbon feedstock such as natural gas, optionally together with one or more of said hydrocarbon products, preferably naphtha.

12. The method according to any one of claims 1 to 11, wherein the hydrogen production unit comprises subjecting the hydrocarbon feedstock to: purification in a purification unit, wherein said purification unit is preferably a sulfur-chlorine-metal absorption unit or a catalytic unit; optionally pre-reforming in a pre-reforming unit; catalytic steam reforming of methane in a steam reforming unit; water gas conversion in a water gas conversion unit; optionally removing carbon dioxide in a _CO2 separator unit; and purifying hydrogen in a hydrogen purification unit.

13. The method according to claim 12, wherein said second stream of recirculated gas is fed to a cleaning unit.

14. The method according to any one of claims 1 to 13, wherein the hydrogen-rich stream or the first recycle stream or the third recycle stream contains hydrogen in a concentration of 50% by volume or higher, and wherein any of said streams is directed through a hydrogen purification unit: before separating said hydrogen-rich stream into the first recycle stream or the third recycle stream, or before directing the first recycle stream to the hydroprocessing stage, or before directing said third recycle stream to the hydrogen production unit.

15. The method according to claim 13, wherein the hydrogen purification unit is a hydrogen purification unit of a hydrogen production unit, and said third recirculated stream is directed through this hydrogen purification unit.

16. The method of claim 15, wherein the hydrogen purification unit is a pressure swing adsorption (PSA) unit, wherein said PSA unit produces an off-gas stream that is used as fuel in a steam reforming unit of a hydrogen production unit, and/or in flame heaters in any of the catalytic hydrotreating units of the hydroprocessing stage, separation units of the separation stage and/or for steam production.

17. The method according to any one of paragraphs 12-16, wherein the steam reforming unit is: a convection reformer, a tubular reformer, an autothermal reformer (ATR), an electrically heated steam methane reformer (e-SMR), or a combination thereof.

18. The method according to any one of claims 1 to 17, wherein before directing the make-up hydrogen stream to the hydroprocessing stage, the make-up hydrogen stream passes through a compressor section comprising a make-up compressor and, if necessary, also a recirculation compressor, wherein the make-up compressor also produces a recirculated stream of hydrogen, which is added to the hydrogen production unit, preferably directly to the second recirculated stream entering the hydrogen production unit, and/or to the purification unit of the hydrogen production unit.

19. The method of claim 18, wherein before directing the first recirculated stream to the hydroprocessing stage, the first recirculated stream is directed through said recirculation compressor.

20. The method according to any one of claims 1 to 19, wherein the feedstock is obtained from raw materials of renewable origin, such as plants, algae, animals, fish, vegetable oil processing products, municipal waste, plastic-rich waste, industrial organic waste such as tall oil or black liquor, or a feedstock obtained from one or more oxygen-containing compounds taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols, wherein said oxygen-containing compounds originate from one or more biological sources, a gasification process, a pyrolysis process, a Fischer-Tropsch synthesis or a methanol-based synthesis.

21. The method according to any one of claims 1 to 20, wherein step i) also comprises adding a feedstock originating from a fossil fuel source such as diesel fuel, kerosene, naphtha and vacuum gas oil (VGO) and/or from the recycling of a hydrocarbon product

22. The method according to any one of claims 1 to 21, wherein the first catalytic hydrotreating is hydrodeoxygenation (HDO), the second catalytic hydrotreating is hydrodewaxing (HDW), and the further catalytic hydrotreating, such as the third catalytic hydrotreating, is hydrocracking (HCR).

23. A method for producing a hydrocarbon product, said method comprising the following stages:

i) directing a feedstock obtained from a fossil fuel source through a hydrotreating step to produce a hydrotreated main stream;

ii) directing the main hydrotreated stream to a separation stage to obtain:

if water flow is required,

hydrogen-rich stream as the first recycle gas stream,

a stream of exhaust gas containing hydrocarbons,

and the specified hydrocarbon product boiling at a temperature above 50°C;

iii) directing the first recycle gas stream to the hydroprocessing stage;

iv) directing the off-gas stream as a second recycle gas stream to a hydrogen production unit to produce a hydrogen stream as a make-up hydrogen stream;

v) directing the make-up hydrogen flow to the hydroprocessing stage;

wherein, prior to step iv), said off-gas stream is sent to a separation step, wherein the separation step is preferably at least one of an amine absorption step, an alkaline scrubber and a sulphur absorber for removing _H2S and thereby producing said second recycle gas stream.

24. A unit for obtaining a hydrocarbon product, including:

- a hydroprocessing section designed to receive feedstock obtained from a renewable source and a compressed stream enriched with hydrogen to produce a main stream subjected to hydrotreatment;

- a separation section designed to receive said main stream subjected to hydrotreatment to obtain an aqueous stream, a hydrogen-enriched stream as a first recycle gas stream, a hydrocarbon-containing off-gas stream as a second recycle stream, and said hydrocarbon product boiling at a temperature above 50°C;

- a separation section, which preferably comprises at least one of an amine absorption stage, an alkaline scrubber and a sulphur absorber, designed to receive said off-gas stream for removing _H2S and thus producing said second recycle gas stream;

- a hydrogen production unit (HPU) designed to receive said second stream of recycled gas and hydrocarbon feedstock to produce a make-up hydrogen stream;

- a compressor section designed to receive said first recycled gas stream and at least a portion of the makeup hydrogen stream obtained in said HPU to generate said compressed hydrogen-enriched feed stream and a recycled makeup hydrogen stream;

- a pipeline for directing said first flow of recirculated gas to said compressor section;

- a pipeline for directing the specified flow of make-up hydrogen from the HPU to the specified compressor section;

- if necessary, a pipeline for recirculating the said recirculated make-up hydrogen flow into the HPU.

- if necessary, means for separating said hydrogen-enriched stream into said first recirculated gas stream and a third recirculated gas stream and a pipeline for directing said third recirculated gas stream to said HPU.

Claims (46)

1. A method for producing a hydrocarbon product, said method comprising the following stages: i) directing the feedstock obtained from a renewable source through a hydrotreating step to produce a hydrotreated main stream; ii) directing the main hydrotreated stream to a separation stage to obtain: an aqueous stream, a hydrogen-enriched stream as a first recycle gas stream, a hydrocarbon-containing off-gas stream, and said hydrocarbon product boiling at a temperature above 50°C; iii) directing the first recycle gas stream to the hydroprocessing stage; iv) directing the off-gas stream as a second recycle gas stream to a hydrogen production unit to produce a hydrogen stream as a make-up hydrogen stream; v) directing the make-up hydrogen flow to the hydroprocessing stage; wherein, prior to step iv), said off-gas stream is sent to a separation step for removing _H2S and thereby producing said second recycled gas stream. 2. The method of claim 1, wherein the separation step is at least one of an amine absorption step, an alkaline scrubber, and a sulfur absorber. 3. The method of claim 1, wherein the method further comprises: vi) separating said hydrogen-rich stream into said first recycle gas stream and a third recycle gas stream, and directing said third recycle gas stream to said hydrogen production unit. 4. The method according to claim 1, wherein in step i) the hydroprocessing step comprises: i-1) directing the feedstock through a first catalytic hydrotreating unit while adding hydrogen to produce a first hydrotreated stream; i-2) directing the first hydrotreated stream to a dewaxing section comprising a second catalytic hydrotreating unit with the addition of hydrogen to obtain said main hydrotreated stream. 5. The method of claim 4, wherein between steps i-1) and i-2) the method further comprises directing the first hydrotreated stream to a separator, such as a high or low pressure separator, for removing _H2S , _NH3 and _H2O , thereby producing said first hydrotreated stream and, if necessary, also producing a vapor stream and a recycle oil stream. 6. The method according to claim 1, wherein in step ii) the separation step comprises: ii-1) directing the hydrotreated main stream to a separator, preferably a cold separator, to obtain said aqueous stream, said hydrogen-rich stream, and a heavy hydrocarbon stream; ii-2) directing the heavy hydrocarbon stream to a fractionation section to obtain said off-gas stream and said hydrocarbon product. 7. The method according to claim 1, wherein in step v) the make-up hydrogen flow is directed to at least one of: the said first catalytic hydrotreating unit; said separator between stages i-1) and i-2), such as a high-pressure stripping column; second catalytic hydrotreating unit; and, if necessary, also an additional catalytic hydrotreating unit, such as a third catalytic hydrotreating unit. 8. The method according to claim 1, wherein the hydrogen production unit includes feeding: said second recycle gas stream and a hydrocarbon feedstock such as natural gas, optionally together with one or more of said hydrocarbon products, preferably naphtha. 9. The method according to claim 1, wherein the hydrogen production unit comprises subjecting the hydrocarbon feedstock to: purification in a purification unit, wherein said purification unit is preferably a sulfur-chlorine-metal absorption unit or a catalytic unit; optionally pre-reforming in a pre-reforming unit; catalytic steam reforming of methane in a steam reforming unit; water gas conversion in a water gas conversion unit; optionally removing carbon dioxide in a _CO2 separator unit; and purifying hydrogen in a hydrogen purification unit. 10. The method according to claim 1, wherein said second stream of recirculated gas is fed to a cleaning unit. 11. The method of claim 3, wherein the hydrogen-rich stream or the first recycle stream or the third recycle stream contains hydrogen at a concentration of 50% by volume or higher, and wherein any of said streams is directed through a hydrogen purification unit: before separating said hydrogen-rich stream into the first recycle stream or the third recycle stream, or before directing the first recycle stream to the hydroprocessing stage, or before directing said third recycle stream to the hydrogen production unit. 12. The method according to claim 9, wherein the hydrogen purification unit is a hydrogen purification unit of a hydrogen production unit, and said third recirculated stream is directed through this hydrogen purification unit. 13. The method of claim 9, wherein the hydrogen purification unit is a pressure swing adsorption unit (PSA unit), wherein said PSA unit produces an off-gas stream that is used as fuel in the steam reforming unit of the hydrogen production unit, and/or in flame heaters in any of the catalytic hydrotreating units of the hydroprocessing stage, the separation units of the separation stage and/or for steam production. 14. The method according to claim 9, wherein the steam reforming unit is: a convection reformer, a tubular reformer, an autothermal reformer (ATR), an electrically heated steam methane reformer (e-SMR) or a combination thereof. 15. The method according to claim 1, wherein before directing the make-up hydrogen stream to the hydroprocessing stage, the make-up hydrogen stream passes through a compressor section containing a make-up compressor, optionally also a recirculation compressor, wherein the make-up compressor also produces a recirculated stream of hydrogen, which is added to the hydrogen production unit, preferably directly to the second recirculated stream entering the hydrogen production unit, and/or to the purification unit of the hydrogen production unit. 16. The method of claim 1, wherein the feedstock is obtained from raw materials of renewable origin, such as plants, algae, animals, fish, vegetable oil processing products, municipal waste, plastic-rich waste, industrial organic waste such as tall oil or black liquor, or a feedstock obtained from one or more oxygen-containing compounds taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols, wherein said oxygen-containing compounds originate from one or more biological sources, a gasification process, a pyrolysis process, a Fischer-Tropsch synthesis or a methanol-based synthesis. 17. The method according to one of claims 1 to 16, wherein step i) also comprises adding a feedstock originating from a fossil fuel source such as diesel fuel, kerosene, naphtha and vacuum gas oil (VGO) and/or from the recycling of a hydrocarbon product. 18. A unit for obtaining a hydrocarbon product, including: - a hydroprocessing section designed to receive feedstock obtained from a renewable source and a compressed stream enriched in hydrogen to produce a main stream subjected to hydrotreatment; - a separation section designed to receive said main stream subjected to hydrotreatment to obtain an aqueous stream, a hydrogen-enriched stream as a first recycle gas stream, a hydrocarbon-containing off-gas stream as a second recycle stream, and said hydrocarbon product boiling at a temperature above 50°C; - a separation section designed to receive said waste gas stream for removing _H2S and thus obtaining said second recycle gas stream; - a hydrogen production unit (HPU) designed to receive said second stream of recycled gas and hydrocarbon feedstock to produce a make-up hydrogen stream; - a compressor section designed to receive said first recycled gas stream and at least a portion of the makeup hydrogen stream obtained in said HPU to generate said compressed hydrogen-enriched feed stream and a recycled makeup hydrogen stream; - a pipeline for directing said first flow of recirculated gas to said compressor section; - a pipeline for directing the specified flow of make-up hydrogen from the HPU to the specified compressor section. 19. The plant of claim 18, wherein the separation section is at least one of an amine absorption stage, an alkaline scrubber, and a sulfur absorber. 20. The installation according to paragraph 18 or 19, additionally including: - a pipeline for recirculating said recirculated make-up hydrogen stream to the HPU; and/or - means for separating said hydrogen-enriched stream into said first recirculated gas stream and a third recirculated gas stream and a pipeline for directing said third recirculated gas stream to said HPU.