WO2013038063A1

WO2013038063A1 - Method and apparatus for producing raw material for biofuel production

Info

Publication number: WO2013038063A1
Application number: PCT/FI2012/050885
Authority: WO
Inventors: Pekka Jokela; Jaakko Nousiainen; Teemu Lindberg
Original assignee: Upm-Kymmene Corporation
Priority date: 2011-09-16
Filing date: 2012-09-13
Publication date: 2013-03-21
Also published as: FI20116284A

Abstract

A method for producing a torrefaction gas product (425) from torrefaction gases, wherein the torrefaction gas product (425) is suitable as raw material for biofuel production. The method comprises receiving torrefaction gases, the torrefaction gases being produced by processing biomass in a torrefaction process and condensing the torrefaction gases to a torrefaction gas condensate, the torrefaction gas condensate comprising the torrefaction gas product (425). An embodiment comprises cooling the torrefaction gases to a condensing temperature, wherein the condensing temperature is between 10 ° C and 40 ° C. In addition, raw material for biofuel production, the raw material having been produced by the method. Furthermore, use of condenser (410) for condensing the torrefaction gases to a torrefaction gas condensate. Still further, an apparatus for producing the torrefaction gas product (425) from torrefaction gases. The apparatus comprises a condenser (410) arranged to condense the torrefaction gases. In an embodiment, the condenser (410) arranged to cool the torrefaction gases to a condensing temperature, wherein the condensing temperature is between 10 ° C and 40 ° C.

Description

Method and apparatus for producing raw material for biofuel production

Field of the Invention The invention relates to producing biofuels from torrefaction gases. Torrefaction gases are received or obtained from a torrefaction process, in which biomass is torrefied. The invention relates to a method for producing raw material for biofuel production from torrefaction gases. The invention relates to a method for producing biofuels from said raw material. The invention relates the raw material. The invention further relates to an apparatus for producing raw material for biofuel production from torrefaction gases. The invention further relates to an apparatus for producing biofuel from said raw material. Background of the Invention

Biomass is commonly used to produce energy. The term biomass refers to materials of biological origin. Biomass may originate from plants, such as wood (stem wood, bark, branch, stump), hay, or straw, or processed material originating from plants such as construction waste, e.g. boards or planks. The biomass is commonly stored before using in energy production. While stored, the biomass may get wet, and wet biomass is known to degrade. The energy content of the biomass decreases during degradation. Furthermore, the energy content of wet biomass, in relation to the mass of the biomass, is less that the energy content of dry biomass. Moreover, the moisture of the biomass increases transportation costs.

To increase the energy content of biomass and to increase the moisture resistance of biomass, the biomass may be torrefied in a torrefaction process. Torrefaction of biomass can be described as a thermal treatment in an inert atmosphere, at a process temperature typically ranging between 200-300 °C. The biomass is held in the process temperature for a treatment time ranging e.g. between 30 minutes and 5 hours. During torrefaction, the properties of biomass are changed, and the quality of torrefied biomass becomes much better for combustion and gasification applications. A torrefaction process is schematically shown in Fig. 1 . In Fig. 1 , biomass is fed to a torrefaction reactor. In the torrefaction reactor, the biomass is heated to the process temperature. The biomass is kept in the torrefaction reactor for the process time. The products of the torrefaction process are torrefied biomass an torrefaction gas. Torrefied biomass may be utilized e.g. in gasification and/or combustion processes. Torrefaction gas comprises steam (as the biomass dries in the process), and volatile hydrocarbons. The torrefaction gas is burned in a burner to obtain heat. Typically the mass of the torrefied biomass is about 70% - 80% of the mass of the same, untorrefied biomass, while the energy content of the torrefied biomass is about 90% of the energy content of the same, untorrefied biomass.

One problem in the process is that the product variety of the torrefaction process, as described, cannot be optimized to produce other products than the torrefied biomass and the heat produced by burning the torrefaction gas.

The quality and properties of the torrefied biomass can be controlled to some extent with the process parameters, namely the process temperature and process time. This also affects the content and amount of the torrefaction gases and therefore affects the amount of heat obtainable by the process.

However, even if the amount of heat is to some extent controllable, the process still produces only heat and torrefied biomass.

Generally biomass can also be used to produce liquid or gaseous biofuel, such as biogasoline components or biodiesel. E.g. the torrefied biomass can be used to produce biofuel e.g. using gasification. The production of biofuel from biomass has received much interest due to the limited crude oil resources. Biofuels may also be used as compounds for fuels. E.g. gasoline may comprise biofuel and crude oil fuel.

Summary of the Invention

The new process uses torrefaction gases in the production of liquid biofuel. In the process, torrefaction gases are used to produce raw material for biofuel production. The raw material for biofuel production is therefore referred to as a torrefaction gas product. At least part of the torrefaction gas product may be hydrotreated to obtain a biofuel mixture comprising said biofuel. Alternatively or in addition, at least a part of torrefaction gas product may be sold and/or transported to another plant for the post processing. In an embodiment, the biofuel mixture is fractionated to obtain biofuel compounds. In an embodiment, torrefaction gas product is produced by condensing torrefaction gases and by separating water from condensed torrefaction gases before hydrotreating. Raw material for biofuel production can be obtained by the process. An apparatus for producing torrefaction gas product, wherein the torrefaction gas product is suitable as raw material for biofuel production, comprises a condenser arranged to condense torrefaction gases to a condensate. The apparatus for producing torrefaction gas product may further comprise means for separating water from the condensate. An apparatus for producing biofuel from torrefaction gases comprises means for producing the torrefaction gas product from the torrefaction gases and a hydrotreatment unit comprising a hydrotreating reactor arranged to treat the torrefaction gas product with hydrogen and at least one supported catalyst. In an embodiment, the apparatus comprises a fractionating unit to fractionate a biofuel mixture and means for conveying the biofuel mixture from the hydrotreatment unit to the fractionating unit. In an embodiment, the apparatus comprises a condenser to condense torrefaction gases, and a separator to separate water from the torrefaction gas condensate to obtain the torrefaction gas product.

A system for producing torrefaction gas product, wherein the torrefaction gas product is suitable as raw material for biofuel production, comprises a torrefaction reactor arranged to torrefy biomass, thereby producing the torrefaction gases, and a condenser arranged to condense said torrefaction gases. A system for producing liquid biofuel from biomass by torrefaction comprises an apparatus for producing biofuel from torrefaction gases and a torrefaction reactor arranged to torrefy biomass thereby producing the torrefaction gases. Description of the Drawings

Figure 1 describes a known torrefaction process, Figure 2a shows a process for producing biofuel from biomass,

Figure 2b shows a process for producing biofuel from torrefaction gases, Figures 3a-3c

show processes for producing torrefaction gases from biomass,

Figure 4 shows a process for producing a torrefaction gas product from torrefaction gases, Figures 5a - 5f

show processes for hydrotreating torrefaction gas product to produce biofuel mixture, and

Figure 6 shows a process and equipment for fractionating a biofuel mixture to biofuel fractions.

Detailed Description of the Invention

Figure 2a shows schematically a process for producing biofuels from biomass using torrefaction. In contrast to prior art, the biofuel is produced from torrefaction gases. The biomass is torrefied to produce torrefied biomass and torrefaction gases. The torrefaction gases are condensed to a condensate comprising water and hydrocarbons. The hydrocarbons are referred to as torrefaction gas product, and can be used as a raw material for biofuel production. The torrefaction gas product may be treated with hydrogen, i.e. hydrotreated, in a hydrotreatment unit 200 to obtain a biofuel mixture comprising at least one type of biofuel. The biofuel mixture is fractionated to biofuels. As will become apparent, the hydrotreatment unit comprises means for hydrodeoxygenating the torrefaction gas product, and may comprise means for performing also other process steps. Figure 2b shows schematically a process for producing biofuels from torrefaction gases. Torrefaction gases are obtained from a torrefaction process. Torrefaction gases are preprocessed, hydrotreated, and postprocessed to obtain at least one type of biofuel, typically at least two types of biofuels. In the preprocessing phase, torrefaction gases are condensed to a torrefaction gas condensate comprising water and hydrocarbons. After condensing, the water is separated from the hydrocarbons to obtain a torrefaction gas product. Hydrotreating comprises reacting the torrefaction gas product with hydrogen in an elevated temperature and pressure. At least one catalyst is utilized in the hydrotreating process. Postprocessing may comprise fractionating the hydrotreated torrefaction gases to different renewable biofuel compounds. Fractionating may comprise distilling. As described, a torrefaction gas product is produced from torrefaction gases. Furthermore, as described, the torrefaction gas product can be used as a raw material for biofuel production. Therefore, the preprocessing of Fig. 2b can be considered an independent process. As an independent process, the product of the preprocessing is the torrefaction gas product. Thus, the preprocessing is a method for producing a torrefaction gas product from torrefaction gases, wherein the torrefaction gas product is suitable as raw material for biofuel production.

In the context of the present invention, "biofuel" means a renewable biofuel containing hydrocarbons produced by catalytic hydrotreating of a hydrocarbon composition obtained from a biological feedstock. Renewable biofuel refers to a liquid fuel, i.e. to a fuel that is liquid at least in room temperature. Renewable biofuel comprises at least one of biogasoline and biodiesel. Biogasoline refers to hydrocarbons distilling at temperatures ranging from 40°C to 210°C, and produced by catalytic hydrotreating of a biological feedstock. Biodiesel refers to hydrocarbons distilling at temperatures ranging from 150°C to 380°C, and produced by catalytic hydrotreating of a biological feedstock. In the present specification and claims "Biodiesel" does not mean a diesel product produced by transesterification of triglycerides in the conventional sense, i.e. biodiesel components produced by the method of the present invention do not contain fatty acid methyl/ethyl esters. It is possible to use the renewable biofuels obtained with the process as a blending components, i.e. blend the renewable biofuels with fuel components obtained from conventional nonrenewable sources. For instance, biogasoline derived from torrefaction gases may be blended with fossil based gasoline, i.e. gasoline derived from mineral oil. The torrefaction gases are obtained from a biological feedstock in a torrefaction process.

To further describe the invention, different parts of the process are discussed in more detail in what follows. The different embodiments of different parts of the process may be combined to obtain an embodiment of the invention.

Referring to Figs. 3a-3c, torrefaction gases are obtained from a torrefaction process, where biomass is torrefied. The biomass may optionally be dried before torrefaction, as shown in Fig. 3a, where a dryer 310 is shown. A dryer 310 may also be included to the embodiments shown in Figs. 3b and 3c. Moreover, the dryer may be omitted from the embodiment of Fig. 3a. A dryer is preferably used, as the dryer reduces the amount of steam comprised in the torrefaction gases.

Fig. 3a describes a torrefaction process and system. In Fig. 3a, biomass in fed to a dryer 310, where the biomass is heated to a drying temperature. The drying temperature may be e.g. between 60 °C and 120 °C. A target for the drying process is to achieve dried biomass with the moisture content of less than about 10 %. Thus, the temperature in the dryer in an embodiment is approximately 100 °C. From the dryer 310, dried biomass and dryer gases are obtained. Depending on the drying temperature, dryer gases may comprise organic compounds. In this case, the dryer gases may be utilized in later process steps, e.g. by mixing the dryer gases with torrefaction gas or by feeding the dryer gas to the condensing unit arranged to condense torrefaction gases, the condensing unit comprising the condenser 410 (Fig. 4). This is illustrated in Fig. 3a by the dash lines from the dryer 310. Preferably the drying temperature is relatively low, as discussed above, to avoid the evaporation of hydrocarbons in the drying process. In this case, the dryer gas consist essentially of air and steam, and the dryer gas may be discharged to air, and not utilized in the process. Furthermore, in subsequent process steps a low steam content of the torrefaction gases is beneficial, and therefore moisture is preferably discharged from the process already before torrefaction. The biomass in the dryer 310 is heated using a first heat source 320. The first heat source 320 heats a first heat exchange medium and supplies the dryer with a heated first heat exchange medium. In the dryer 310, the biomass may be heated by contacting it with the first heat exchange medium. Alternatively the biomass may be heated by heating the dryer 310, e.g. from outside the dryer. In addition or alternatively, the biomass may be heated by guiding the first heat exchange medium through the biomass, e.g. in heat exchange tubes running through a bed of biomass.

The first heat exchange medium may be gaseous. The first heat exchange medium may be led through dryer 310. E.g. the dryer 310 may be a fluidized bed dryer, in which case biomass forms a bed in the dryer 310, and the first heat exchange medium is conveyed through the bed. Alternatively, the dryer may be a rotary drum dryer. In Fig. 3a, the first heat exchange medium is recycled to the first heat source 320. The first heat source may be e.g.

- a boiler arranged to burn biomass,

- the torrefaction gases, or

- the torrefied biomass.

The first heat exchange medium may be heated using a heat exchanger. The system comprises means for conveying the first heat exchange medium from the first heat source 320 to the dryer 310. If torrefaction gases are used as the first heat source, the torrefaction gases are cooled. If torrefied biomass is used as the first heat source, the torrefied biomass is cooled.

Referring to Fig. 3a, the embodiment comprises a torrefaction reactor 300. The dried biomass is conveyed from the dryer 310 to the torrefaction reactor 300. In the torrefaction reactor 300, the biomass is heated to a process temperature. The process temperature may range between 200 °C and 300 °C. The biomass is held in the torrefaction reactor for a treatment time. The treatment time may range between 10 and 20 minutes. The heating rate of the biomass in the torrefaction process is typically relatively low, e.g. less than 50 °C per minute. The amount and quality of the torrefaction gases may depend on the process temperature and process time. To increase the yield of the torrefaction gases, the process temperature may be increased up to 350 °C. To increase the yield of the torrefaction gases, the process time may be increased up to 1 hour or more. The atmosphere in the torrefaction reactor and torrefaction process is inert to prohibit burning of the biomass. Inert atmosphere refers to a gas essentially not reacting with biomass in the process. Inert atmosphere may comprise a majority of nitrogen. The inert atmosphere may comprise only a small amount of oxygen, e.g. the oxygen content may be less than 6 vol-%. Examples of an inert atmosphere include:

- nitrogen (N₂)

- air, from which at least part of oxygen is removed to decrease the oxygen content below 6 vol-%, and

- flue gases from a combustion process, whereby the combustion process has reduced the oxygen content of air when producing the flue gases, and increased the content of other substances such as carbon dioxide, carbon monoxide and steam comprised in the flue gases. When using flue gases as heating medium in torrefaction, the remaining oxygen content in flue gases may be 3-5 vol-%.

Alternatively, the torrefaction reactor can filled with biomass, whereby the oxygen content in the reactor remains small. If air is not circulated in the torrefaction reactor, the atmosphere in the reactor becomes inert as soon as most of the oxygen has reacted with the biomass.

Typically the yield of torrefaction gases depends on the process. For example, in a process temperature of 300 °C and process time 10 minutes, the torrefaction gas yield may be on the order of 30 mass-% of the feedstock, i.e. untorrefied biomass.

The torrefaction process is not pressure sensitive. The process pressure in the torrefaction reactor is often at atmospheric pressure. However, there are only economic reasons why the process is not pressurized. In principle the pressure range could be e.g. from atmospheric to 20 bar. The biomass in the torrefaction reactor 300 is heated using a second heat source 330. The second heat source 330 heats a second heat exchange medium and supplies the torrefaction reactor with the heated second heat exchange medium. In the torrefaction reactor 300, the biomass may be heated by contacting it with the second heat exchange medium. Alternatively the biomass may be heated by heating the torrefaction reactor 300, e.g. from outside the reactor.

The second heat exchange medium may be a liquid. In an embodiment, the second heat exchange medium consist of oil, and the second heat exchange medium heats the torrefaction reactor. The torrefaction reactor 300 may be a rotary drum with a small angle of inclination. In this case the second heat exchange medium is recycled back to the heat source. The second heat source may be e.g. a boiler arranged to burn biomass. The heat exchange medium may be heated using a heat exchanger. The system comprises means for conveying the heat exchange medium from the heat exchanger to the torrefaction reactor 300.

The second heat exchange medium may also comprise water. Depending on the operating pressures, the second heat transfer medium may comprise at least one of superheated steam, steam, and water. The cooled second heat transfer medium is recycled back to the second heat source 330.

The second heat source may comprise boiler arranged to burn biomass and the second heat transfer medium may be the flue gases from the boiler. In this case, the biomass is burned in the boiler using air, whereby the air is heated and some of the oxygen is consumed in the process. The flue gases of the process may be used as the second heat exchange medium. In this case the second heat exchange medium is not necessarily recycled back to the boiler. The hot flue gases may be e.g. contacted with the biomass in the torrefaction reactor to heat the biomass. As a result, the torrefaction gases may comprise the flue gases. The torrefaction reactor may be a fluidized bed, and flue gases may be used to fluidize the biomass. Still further, the second heat source may comprise a fluidized bed boiler arranged to burn biomass in fluidized boiler comprising a fluidized bed of inert, solid, and granular material. The second heat transfer medium may comprise the hot granular material. In this case, hot granular material is conveyed to the torrefaction reactor. The hot granular material may be used to heat the torrefaction reactor or the hot granular material may be contacted with the biomass, e.g. by mixing the granular material and the biomass in the torrefaction reactor. As the granular material heats the biomass, the granular material cools. If needed, the granular material may be separated from the biomass. The cooled granular material is conveyed back to the fluidized bed boiler. In an embodiment, the torrefaction reactor comprises a fluidized bed, and suitable gases, for example inert gases may be used to fluidize the mixture of biomass and hot granular material.

The first and the second heat sources 320, 330 may be the same heat source, e.g. the same boiler.

In the embodiment shown in Fig. 3b, the biomass in the torrefaction reactor 300 is heated by recycling part of the torrefaction gases. Torrefaction gases are recycled in the process, and part of torrefaction gases is recycled back to the torrefaction reactor. Torrefaction gases that are recycled to the process are heated using a heat exchange medium similar to the second heat exchange medium described in Fig. 3a. The torrefaction reactor 300 may be a fluidized bed, and torrefaction gases may be used to fluidize the biomass. Part of the torrefaction gases are led to the condensing, to be used for the production of renewable biofuel.

In the embodiment shown in Fig. 3c, the biomass in the torrefaction reactor is heated with a heat exchange medium, e.g. oil. Torrefaction gases are recycled in the process, and part of torrefaction gases is recycled back to the to torrefaction reactor. The torrefaction reactor may be a fluidized bed, and torrefaction gases may be used to fluidize the biomass. Part of the torrefaction gases are led to the condensing, to be used for the production of biofuel.

The torrefaction gases are in gaseous form when leaving the torrefaction reactor 300. At this point the temperature of the torrefaction gases may be essentially the same as the process temperature, i.e. between 200 °C and 300 °C, or between 200 °C and 350 °C. Torrefaction gases comprise light hydrocarbons. Torrefaction gases may comprise terpenes (C₅H₈)_n. In particular, torrefaction gases may comprise at least one of monoterpenes (where n=2), diterpenes (n=4), and sesquiterpenes (where n=3). As an example, turpentine is a mixture of terpenes, and thus torrefaction gases may comprise turpentine. In addition, torrefaction gases may comprise light fatty acids of e.g. 12 or 14 carbon atoms. Torrefaction gases may comprise also aromatis, e.g. furfural. In addition, torrefaction gases may comprise other light hydrocarbons such as phenol and hydroxyl acetone. Torrefaction gases may comprise also very light hydrocarbons of 1 - 3 carbon atoms, such as acetic acid, lactic acid, formic acid, and methanol. These hydrocarbons may be used to produce biofuel. Therefore, torrefaction gases may be used to produce biofuel. In addition to hydrocarbons, torrefaction gases comprise steam (i.e. gaseous water).

In comparison to pyrolysis oil obtained from a pyrolysis process, wherein the pyrolysis temperature is between 450 °C and 500 °C, the pyrolysis oil comprises substances of much higher molecular weight, e.g. suspended solids and pyrolitic lignin (e.g. 22-36 %); hydroxyacetaldehyde (e.g. 8-12 %); and levoglucosan (e.g. 3-8 %). In contrast, torrefaction gases are free of lignin and lignin fragments; or essentially free of lignin and lignin fragments. Moreover, torrefaction gases are free of hydroxyacetaldehyde or essentially free of hydroxyacetaldehyde. As discussed, torrefaction gas may consists of steam and light hydrocarbons. The torrefaction gas may also comprise some impurities, whereby the torrefaction gas may consists essentially of steam and light hydrocarbons.

Even if Figs. 3a-3c describe the torrefaction process for producing torrefaction gases, the invention is not limited to a process where torrefaction gases are actually produced. In an embodiment, torrefaction gases are otherwise provided for a hydrotreating process. Preprocessing may be seen as part of the hydrotreating process. Torrefaction gases may be produced e.g. in a process separated from the hydrotreating process. The process producing the torrefaction gases may be considered a torrefaction gas provider, while the hydrotreating process receives the torrefaction gases. Further, the hydrotreating process uses torrefaction gases as an input material, which input material is to be hydrotreated with the process. In an embodiment, torrefaction process and hyrotreating processes are integrated, whereby the hyrotreating process receives at least part of the torrefaction gases produced in a torrefaction process.

A torrefaction process, as described above, may also be an integral part of a method for producing liquid biofuel from biomass. Similarly an apparatus for producing biofuel mixture from torrefaction gases (i.e. the hydrotreatment unit 200) may be an integral part of a system for producing biofuel from biomass by torrefaction. In this case an embodiment of torrefaction, e.g. one of the embodiments described above, is integrated with the hydrotreatment unit 200, and means for conveying torrefaction gases from torrefaction reactor to the hydrotreatment unit 200 are provided. Referring to Fig. 4, in an embodiment water is separated from torrefaction gases. Torrefaction gases are conveyed to a condenser 410, where torrefaction gases are cooled. The torrefaction gases are cooled to a condensing temperature ranging between 10 °C and 40 °C. In the condenser 410, and in the described temperature range, part of the torrefaction gases condense to a liquid and part of it remains in gaseous form. As an example, about 5/6 (as measured in weight) of the torrefaction gases may be condensable, while 1 /6 of the torrefaction gases may be un-condensable. This ratio may depend of the torrefaction process temperature and time. Un-condensable gases comprise mainly carbon dioxide and carbon monoxide. It may comprise also hydrocarbons with the boiling point of less than the condensing temperature, which are hard to use in the production of biofuel. Therefore, in the embodiment shown in the figure, these hydrocarbons are burned.

The condensate, i.e. the condensed torrefaction gases, comprise water and hydrocarbons having boiling point over the condensing temperature. The condensate is conveyed to a separator 420. In the separator 420, water is separated from the condensate, and the remaining liquid is referred to as torrefaction gas product 425. The torrefaction gas product 425 may be further processed to biofuel, while water may be discharged from the process. In the embodiment shown in Figs. 3a-3c and 4, the system further comprises means for conveying torrefaction gases from the torrefaction reactor 300 to the condenser 410 and means for conveying the condensate from the condenser 410 to the separator 420.

The torrefaction gas product 425 may be further processed to biofuel in the hydrotreatment unit 200 that is located in the vicinity of the condenser 410 (or the separator 420, if the separator is used). Alternatively, a hydrotreatment unit 200 may be located further away from the condenser 410. Means for conveying the torrefaction gas product 425 from the condenser or the separator 420 to the hydrotreatment unit 200 may comprise at least one of a pipeline and a movable container. The movable container may be arranged in connection with a vehicle such as a truck, a train, or a ship. The torrefaction gas product 425 may also be sold as such, whereby further processing steps are not needed.

The torrefaction gas product 425 may consist of the torrefaction gas condensate, whereby water is not necessarily separated from the torrefaction gas condensate. When torrefaction gas product 425 consists of the torrefaction gas condensate, only a part (i.e. the hydrocarbons) of the torrefaction gas product may be used to produce the biofuel. However, preferably the torrefaction gas condensate comprises the torrefaction gas product 425 and water, and the torrefaction gas product 425 is obtained by separating the water from the torrefaction gas condensate. If the torrefaction gas product 425 is essentially free from water, essentially all of the torrefaction gas product 425 may be used to produce the biofuel.

Referring to Fig. 4, the embodiment further comprises means for conveying the torrefaction gas product 425 from the separator 420 to the hydrotreatment unit 200. The feed of the torrefaction gas product may be controlled with a pump 450. The hydrotreatment unit 200 comprises a hydrotreating reactor 530. The embdiment comprises, in between the torrefaction reactor and the hydrotreatment unit 200, a condenser 410 and a separator 420. In the condenser, light hydrocarbons are discharged from the process. In the separator, water is separated from the condensate and thus the condensable hydrocarbons (at the condensing temperature discussed above) are conveyed as torrefaction gas product 425 to the hydrotreating reactor 530. Figs. 5a - 5f describe hydrotreating of the torrefaction gas product 425 and the hydrotreatment unit 200. The torrefaction gas product 425 is passed through at least one guard unit 510 prior to hydrotreating. The guard unit(s) 510 may be integrated in a hydrotreating reactor, as will be discussed. Referring to Fig. 2a, the hydrotreatment unit 200 comprises the hydrotreating reactor 530. The hydrotreatment unit may further comprise at least one of:

- at least a second hydrotreating reactor 530b,

- at least one guard unit 510,

- the condenser 410,

- the separator 420,

- the pump 450, and

- a gas separator 550.

Thus, e.g. the condenser 410, the separator 420, and the pump (Fig. 4) may be considered to be comprised in the hydrotreatment unit 200. The condenser 410 and the separator 420 may be integrated in one condensing unit. Thus, the condenser 410 and the separator 420 may be considered to form a condensing unit, the condensing unit being separated from the hydrotreatment unit 200. In Fig. 5a, the torrefaction gas product 425 is passed through at least one of the guard units 510a and 510b. The number of guard units 510 may also be one, three, four, or more. Thus, the number of guard units may be at least one. The guard unit 510 comprises at least one bed of guard bed material comprising beads, grains, or granules of suitable passive or inert material, such as Al₂0₃, SiC, Si0₂, or glass. The bed of the guard unit is referred to as a guard bed. The guard bed may also comprise a minor amounts of an active catalyst material. Suitable catalyst materials include the same catalyst materials that are used in the hydrotreating reactor 530, and will be discussed in more detail below. The guard unit 510a and/or 510b acts to remove harmful substances from the torrefaction gas product 425 feed. The harmful substances may comprise metal residues. The guard unit/units can also be used as traps for elements acting as catalyst poisons in the main hydrotreating reactor.

The apparatus may comprise valves 505. The valves 505 are used to select the guard unit(s) 510 to be used, in a manner obvious to a person skilled in the art. The valves may be used for example to isolate one or more guard units 510 from the system. This enables a continuous operation of the process even if one or some of the guard units are under maintenance. Maintenance of a guard unit may comprise regenerating a guard bed material for further use or changing the guard bed material. In Fig. 5a the guard units are arranged in series. If the system comprises more than one guard unit, the guard units may also be arranged in parallel.

The hydrotreatment unit 200 can be designed without valves 505. Then the guard beds cannot be isolated and all reactors must be maintained at the same time. In the embodiments shown in Figs 5a - 5f , hydrogen is fed to the torrefaction gas product 425, before torrefaction gas product 425 enters the guard unit 510. Hydrogen may be fed to the process also to a hydrotreating reactor 530. Hydrogen is not necessarily fed before the guard unit 510. The temperature of the feed can be controlled with a temperature controlling unit 500.

From the guard unit 510, the torrefaction gas product feed 425, possibly together with hydrogen and/or supplementary sulphur, is conveyed to at least one hydrotreating reactor 530. In the hydrotreating reactor, the torrefaction gas product 425 is reacted with hydrogen using at least one catalyst. The catalyst is comprised in at least one catalyst bed. Before the feed is supplied to the reactor, the catalyst is sulfided using suitable sulphur compound, as informed by the catalyst vendor.

In accordance with the present invention the hydrotreatment in the hydrotreatment unit 200 may be accomplished utilizing a hydrotreating catalyst. The hydrotreatment unit 200 may comprise one or more hydrotreating reactors 530. In the hydrotreating reactor 530 or in the hydrotreating reactors 530 the torrefaction gas product feed from guard units is contacted with at least one hydrotreating catalyst. Examples of suitable hydrotreating catalysts include, but are not limited to, catalyst containing Group VIB and Group VIII metals of the lUPAC Periodic Table.

Preferably the catalyst is selected from catalysts containing Ni, Mo, Co, Pt, Pd and W as monometallic or multiple metal combination catalysts and catalyst mixtures thereof. The catalyst is supported by a suitable support material. The support material is selected from zeolites, activated alumina, silica, silica-alumina, activated carbon, and mixtures thereof.

In an embodiment, a catalyst for hydrodeoxygenating (HDO) of the torrefaction gas product 425 is used in the hydrotreating reactor 530. In another embodiment, in addition to a HDO catalyst, also a hydrodewaxing (HDW) catalyst is used. In another embodiment, in addition to a HDO catalyst, also a hydroisomerization (HI) catalyst is used. The catalyst may be arranged in the reactor as a combination or a mixture of different catalysts or a combination of several thin layers or beds of different catalysts. As torrefaction gases are essentially free from hydrocarbons of high molar weight, in some embodiments, a catalyst or catalysts for only hydrodeoxygenating (HDO) is/are used in the hydrotreating reactor(s).

A catalyst for hydrodeoxygenating (HDO) is intended for removal of oxygen but is also capable of removing other heteroatoms such as sulphur and nitrogen from organic compounds. Hydrotreatment may also result to decarboxylation and/or decarbonylation of carbonyl containing organic compounds as well as hydrogenation of carbon-carbon double bonds of unsaturated organic compounds and ring opening of cyclic and polycyclic organic compounds. Effective HDO catalysts include those consisting of a mixture of CoO and MoO₃; and those consisting of a mixture NiO and MoO₃. The former is referred to as CoMo and the latter as NiMo.

The HDO catalyst is a supported catalyst, the catalyst being supported by support material. The support material is selected from the group comprising Al₂0₃, SiC, activated carbon, zeolite, zeolite-AI₂0₃, Al₂0₃-Si0₂, and their combinations. NiMo with an Al₂0₃ support is particularly effective.

A catalyst for hydrodewaxing (HDW) is capable of catalyzing the same reactions as HDO catalysts. In addition, HDW catalysts can effect isomerisation (e.g. conversion of n-hydrocarbons to iso-hydrocarbons) and cracking, which decreases the hydrocarbon chain length (e.g. conversion of cymene to toluene). Effective HDW catalysts comprise those containing NiW. The HDW catalyst is a supported catalyst and the support material is selected from the group comprising Al₂0₃, SiC, activated carbon, zeolite, zeolite-AI₂0₃, Al₂0₃-Si0₂, and their combinations. An Al₂0₃ support is preferred. A catalyst for hydroisomerization (HI) is capable of catalysing isomerization reactions in a hydrotreatment unit. Suitable HI catalysts contain molecular sieve and/or a metal from Group VIII and/or a support. The HI catalyst is a supported catalyst and the support material is selected from the group comprising SAPO-1 1 , SAPO-41 , ZSM-22, ZSM-23, ferrite, Al₂0₃, Si0₂, and their combinations. Preferably, the HI catalyst contains SAPO-1 1 or SAPO- 41 or ZSM-22 or ZSM-23 or ferrite and Pt, Pd, or Ni and AI₂O₃ or SiO₂. Typical HI catalysts are, for example, Pt/SAPO-1 1 /AI₂O₃, Pt/ZSM-22/AI₂O₃, Pt/ZSM-23/AI₂O₃, and Pt/SAPO-1 1 /SiO₂. The hydrotreatment unit 200 comprises at least one hydrotreating reactor 530. The hydrotreating rector 530 comprises at least a first catalyst bed 534. At least one of the catalyst beds comprises at least one type of a HDO catalyst. For example, the first catalyst bed 534 may comprise a HDO catalyst, wherein the first refers to the catalyst bed closest to the inlet of the reactor. In addition, the hydrotreating reactor 530 may comprise a second catalyst bed. The second catalyst bed may comprise a suitable HDW catalyst or a suitable HI catalyst. Still further, the hydrotreating reactor 530 may comprise more than two catalyst beds. In addition, the system may comprise a second hydrotreating reactor 530b. The second hydrotreating reactor comprises a second catalyst bed. The second catalyst bed may comprise a suitable HDW catalyst or a suitable HI catalyst. In the embodiment shown in Fig. 5a, the hydrotreating reactor 530 comprises only one catalyst bed 534. In an embodiment the catalyst bed 534 comprises only a catalyst selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo.

In another embodiment, where the hydrotreating reactor 530 comprises only one catalyst bed 534, the catalyst bed comprises a first catalyst and a second catalyst. The first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and the second catalyst is selected from the group of hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW. The ratios of the HDO and HDW catalysts change so that the proportion of the HDW catalyst grows towards the outlet of the reactor, the outlet being the bottom part of the hydrotreating reactor 530 in Fig. 5a. Thus, the bottommost part of the catalyst bed 534 of the reactor 530 may comprise HDW catalyst as the sole catalyst. The topmost part of the catalyst bed 534 of the reactor 530 may comprise HDO catalyst as the sole catalyst. As the catalyst bed 534 comprises two catalysts, and the ratios of the HDO and HDW catalysts change so that the proportion of the HDW catalyst grows towards the outlet of the reactor, in this embodiment the catalyst bed comprises a mixture or combination of the two catalysts.

In a still further preferred embodiment comprising one hydroprocessing reactor, the catalyst in the rector is a combination or a mixture or a combination of several thin layers or beds of HDO and HDW catalysts. It may be necessary to supply supplementary sulphur to the hydrotreating step to maintain the catalytic activity of the hydrotreating catalyst, depending on nature of the feedstock. If desired, supplementary sulphur may be supplied to the hydrotreating step. Said sulphur can be hydrogen sulphide (H₂S) and/or any sulphur containing compound that produces hydrogen sulphide in the process. Examples of suitably sulphur containing compounds include, but are not limited to, organic sulphur compounds, such as dimethyl disulphide. In the embodiment of Fig. 5a, before the feed in introduced to the guard unit 510, dimetyl sulphide is added to the feed using a sulfide pump 520. Referring to Fig. 5b, in an embodiment the hydrotreating reactor 530 comprises several catalyst beds 534a, 534b, and 534c containing catalysts. The catalyst beds are packed on top of each other. Each catalyst bed comprises at least one of a first catalyst and a second catalyst, where the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and the second catalyst is selected from the group of hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW. The catalyst beds 543 are separated by layers of suitable inert material 532. The proportion of the catalysts in the catalysts beds 534 vary from top to bottom of the reactor in such a way that the proportion of the HDW catalyst grows towards the bottom of the reactor. The top of the reactor refers to the inlet end of the reactor and the bottom of the reactor refers to the outlet end of the reactor. Thus, the proportion of the HDW catalyst in the bed 534a is smaller than proportion of the HDW catalyst in the bed 534b or 534c.

In an embodiment, a minor amount (1 - 6%) of HDW catalyst is mixed with the HDO catalyst loaded in the topmost bed 534a of the reactor. In another embodiment, the bottommost bed 534c comprises minor amount (1 - 6%) of HDO catalyst.

In a still further preferred embodiment comprising one hydroprocessing reactor, the catalyst in the rector is a combination or a mixture or a combination of several thin layers or beds of HDO and HDW catalysts.

In another embodiment, the the hydrotreating reactor 530 comprises several catalyst beds 534a, 534b, and 534c containing only hydrodeoxygenating catalyst. As explained above, the catalyst beds are packed on top of each other. Each catalyst bed comprises at least one of a first catalyst, and the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, comprising supported CoMo and NiMo catalysts. The catalyst layers may be diluted with a suitable passive or inert material, such as Al₂0₃, SiC, Si0₂ or glass. The amount of diluting material may be arranged to change gradually so that proportion of the catalysts in the catalysts beds 534 vary from top to bottom of the reactor in such a way that the proportion of the HDO catalyst grows towards the bottom of the reactor.

The number of catalyst beds 534 in the hydrotreating reactor 530 may be e.g. one, two, three, or more than three.

In the embodiments shown in Figs. 5c and 5d, the hydrotreating reactor 530 comprises only two catalyst beds. The first catalyst bed 534a (the first referring to the catalyst bed closest to the inlet of the reactor) comprises a first catalyst, wherein the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo. The hydrotreating reactor 530 comprises also a second catalyst bed 534b.

In the embodiment shown in Fig. 5c, the second catalyst bed (534b) comprises a second catalyst. The second catalyst is selected from the group of hydrodeoxygenating (HDO) and hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW.

In the embodiment shown in Fig. 5d, the second catalyst bed comprises a second catalyst. The second catalyst is selected from the group of hydroisomerization (HI) catalysts, the group of hydroisomerization (HI) catalysts comprising a Group VIII metal, such as Pt. However, both HDO and HDW catalyst may require the use of supplementary sulphur, while the HI catalyst cannot withstand sulphur. Referring to Fig. 5d, means for removing gases 550 from the gases exiting the hydrotreating reactor 530 are provided to the system. If a HI catalyst is used, the means for removing gases comprise also means for removing sulphur 550b from the gases. Sulphur is removed after the first catalyst bed, before the second catalyst bed comprising HI catalyst. The catalysts in separate layers can be formed of catalyst granules of different size and form. Further, the amounts of active catalyst and active metals in the active catalyst may vary. In the process of hydrotreating, the torrefaction gas product 425 is contacted with hydrogen gas under catalytic conditions in the hydrotreating reactor 530. In the hydrotreating reactor 530, the HDO catalyst provides hydrotreatment of the torrefaction gas product 425 feed. The temperature in the hydrotreating reactor 530 is between about 250 °C and about 450 °C, preferably between 350 °C and 410 °C. The pressure in the hydrotreating reactor 530 depends on the catalyst used. In case the catalyst comprises a HDW catalyst, a pressure ranging between 80 bar and 1 10 bar is used. The temperature in the hydrotreating reactor 530 may be controlled with at least one of: a heat exchanger 515, the amount of recycled gas 540, and the temperature of the added hydrogen.

In the hydrotreating reactor, some of the hydrogen may remain unreacted. In the embodiments shown in Figs. 5a-5f, the unreacted hydrogen is separated from the hydrocarbons in a gas separator 550. Hydrogen may be recycled to the process. Hydrogen may be recycled to the hydrotreating reactor 530, or hydrogen may be recycled to the process before the guard unit(s) 510, as depicted in Fig. 5a. The gas separator separates hydrogen from the hydrocarbons, thereby producing a biofuel mixture 560. The biofuel mixture 560 comprises a fraction of biofuel such as a fraction of biogasoline or biodiesel. The biofuel mixture 560 can be fractionated to different biofuel fractions, as will be discussed later. In addition, also other gaseous compounds 570 are produced, as will be discussed later. It is possible to add all the needed hydrogen before the guard unit(s) 510, and thus not add hydrogen later to the process.

Figs. 5e and 5f describe other embodiments of the hydrotreatment unit 200. In the figures, only the last guard unit 510b is shown; the earlier guard unit(s), the temperature controlling unit 500 and the supplementary sulphur pump 520 may be present, as discussed together with Figs. 5a-5d. The hydrotreatment unit 200 comprises two hydrotreating reactors 530a and 530b. The hydrotreating reactors are arranged in series. Thus, the flow from the guard unit 510b enters the first hydrotreating reactor 530a. Further, the flow from the first hydrotreating reactor 530a enters the second hydrotreating reactor 530b. The first hydrotreating reactor 530a comprises a first catalyst bed 534a. The second hydrotreating reactor 530b comprises a second catalyst bed 534b. In these embodiments, each hydrotreating reactor 530 comprises only one active catalyst bed 534a or 534b. The catalyst bed 534 comprises only one catalyst. The catalyst of the catalyst bed may be selected individually for each hydrotreating reactor. In an embodiment, a first catalyst is used in the first hydrotreating reactor 530a and a second catalyst is used in the second hydrotreating reactor 530b. The first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo.

In the embodiment shown in Fig. 5e, the second catalyst is selected from the group of hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW. In the embodiment, there is no need for sulphur removal in between the hydrotreating reactors 530a and 530b. Sulphur is removed from the product flow by means for gas separation 550 after the second hydrotreating rector 530b.

In the embodiment shown in Fig. 5f, the second catalyst is selected from the group of hydroisomerization (HI) catalysts, the group of hydroisomerization (HI) catalysts comprising a Group VIII metal, such as Pt. In the embodiment, sulphur is removed from the hydrodeoxygenated flow by means for gas separation 550b after the first catalyst bed 543a. The means for gas separation 550b after the first catalyst bed 543a may comprise also means for separating hydrogen. The hydrogen may be recycled to the process, as depicted in the figure. In Figs. 5e and 5f, hydrogen is supplied to both the hydrotreating reactors 530a and 530b. In another embodiment, hydrogen is supplied only to the first hydrotreating reactor 530a. Still further, hydrogen may be supplied to the terrefaction gas condensate feed, as depicted in Figs. 5e and 5f with a dash- dot line (c.f. also Fig. 5a). Even if not explicitly shown in Figs. 5e and 5f, the temperature in any one of the hydrotreating reactor(s) 530a and 530b may be controlled with at least one of: a second heat exchanger 515, the amount of recycled gas 540 (c.f. Fig. 5a), and the temperature of the added hydrogen. In an embodiment, the guard unit or a guard bed is integrated into a hydrotreating reactor. In this embodiment, the hydrotreating reactor 530, 530a or 530b comprise a guard bed 510 in the receiving end of the hydrotreating reactor, as first material layer. The receiving end refers to the part of the hydrotreating reactor that receives the torrefaction gas product 425 feed. Thus after the guard bed, in the direction of the flow, the hydrotreating reactor 530 comprises catalyst beds 534 and layers of inert material 532.

The amount of hydrogen gas needed in the hydrotreating step is determined by the amount and the nature of the torrefaction product. A suitable amount of hydrogen can be determined by a person having ordinary skills in the art. A suitable amount of hydrogen can be proportional to the amount torrefaction gas product 425, as will be discussed below. Referring to Figs. 5a - 5f, in addition to torrefaction gas product feed 425, hydrogen is conveyed to the hydrotreating reactor 530. The torrefaction gas product is pumped to the hydrotreating reactor 530 at a desired speed with a pump 450 (Fig. 4). A suitable feed rate of the torrefaction gas product 425 feed is proportional to the amount of the catalyst in the hydrotreating reactor. A weight hourly spatial velocity, WHSV, can be calculated according to the following equation:

WHSv[h^~l ] = ^{Vfeed[g ,h]} wherein Vf_eed[g/h] means a pumping velocity of the torrefaction gas product 425, and mcataiyst[g] means the total mass of the catalyst(s) in the hydrotreating reactor(s). In an embodiment, the WHSV of the torrefaction gas product is in the range from 0.1 h^"1 to 5 h^"1, and is preferably in the range of 0.3 h^"1 - 1 .5 h^"1. This enables the calculation of a suitable torrefaction gas product 425 feed rate, as measured in g/h by V_feed[g/h]=WHSV[h^~1]xmcataiyst[g]- Knowing the density, the torrefaction gas product 425 feed rate in l/h can be calculated. Using the information on the suitable torrefaction gas product 425 feed rate V_feed[g/h], the torrefaction gas product flow can be controlled. The torrefaction gas product flow can be controlled e.g. with the pump 450 (Fig. 4).

The hydrogen feed rate is proportional to the amount of torrefaction gas product 425 feed rate. The volumetric ratio of hydrogen to torrefaction gas product 425 varies between 600 Nl/I and 4000 Nl/I, and is preferably in the range of 1300 Nl/I - 2200 Nl/I. As hydrogen, H₂, is gaseous, its volume is measured in normal litres (Nl). Normal litre is a unit of mass for gases equal to the mass of 1 litre at NTP conditions. Hydrogen may be added before the guard units and to the feed entering at least one hydrotreating reactor. The volume of hydrogen in the above measure refers to the total volume added to different reactors/units.

The gas separator 550 or 550b is arranged to separate hydrogen from the flow to the gas separator. In an embodiment, the gas separator is also arranged to separate, from the flow, at least one of: sulfur compounds, i.e. hydrogen sulfide, steam, and light hydrocarbons. These compounds are in gaseous form. The gases are commonly referred to by the reference number 570. The gases 570 are discharged from the process. The light hydrocarbons of the gas 570 may be eg. burned in a boiler. The gas separator may comprise a stabilator arranged to remove hydrogen sulfide from the feed. The removed hydrogen sulfide is comprised in the gases 570.

The last gas separator 550 may be arranged to perform at least one flash step on the flow entering the gas separator 550. The term "last" here refers to the direction of the flow, cf. Figs. 5d and 5f. The last gas separator 550 is after another gas separator 550b. More than one flash step is appropriate when the components of the feed have a broad range of masses. Each flash step comprises heating the flow. A first flash step may be employed to remove sour gases, hydrogen and light hydrocarbons from the flow, and a second (lower pressure) flash step can then be employed to separate the hydrocarbons from the sour gases and hydrogen. A stripping or stabilisation step can also be employed for removing sour gases. This may be performed after a flash step.

The biofuel mixture 560 obtained from the gas separator 550 comprises fuel grade hydrocarbons having a boiling point at most 380 °C.

Referring to Fig. 6, the biofuel mixture 560 is postprocessed to produce at least one type of biofuel, e.g. a biodiesel fraction 625 or a biogasoline fraction 635. The biofuel mixture 560 is conveyed to a fractionating unit 610 to fractionate the biofuel mixture 560. Thus the system comprises means for conveying biofuel mixture 560 from the hydrotreating reactor 530, 530a, 530b to the fractionating unit 610. In an embodiment, the fractionating unit 610 comprises a distiller arranged to separate different biofuel fractions from the biofuel mixture 560 by distillation. In an embodiment, the fractionating unit 610 comprises separation column arranged to separate different biofuel fractions from the biofuel mixture 560.

In the fractionating unit 610, various fuel grade hydrocarbon fractions are separated from the biofuel mixture 560. One of the fractions recovered is a middle distillate, i.e. hydrocarbon fraction having a boiling point typical in diesel range, i.e. from 150 °C to 380 °C, meeting the specification of EN 590 diesel. This means that max 65 % of the hydrocarbons are recovered at 250 °C, min 85 % recovered at 350 °C, 95 % recovered at max 360 °C according to EN ISO 3405 method. This fraction is referred to as the biodiesel fraction 625. The biodiesel fraction 625 is conveyed to a diesel storage tank 620.

Also hydrocarbon fractions distilling at temperatures ranging from 40 °C to 210 °C are obtained. These fractions are useful as high quality gasoline fuel, or as blending components for gasoline fuel. This fraction is referred to as the biogasoline fraction 635. The biogasoline fraction 635 is conveyed to a gasoline storage tank 630.

Also hydrocarbon fractions distilling at temperature of about 370 °C are obtained. These fractions are useful as naphta, or as blending components for naphta. Naphta is low grade gasoline having similar distillation properties than gasoline. The fraction distilling after 370 °C can be recirculated back to the process if HDW catalyst is used. If only HDO catalyst is used this heavy fraction must be separated if less than 95% of the diesel is distillated in the temperature of 360 °C. The separated heavy fraction can be used for example as heating oil.

This fraction is referred to as the naphta fraction 645. The naphta fraction 645 is conveyed to a naphta storage tank 640.

Said hydrocarbon fractions 625 and 635 can also be used as blending components in standard fuels.

Also hydrocarbon fractions 655 distilling at temperature below 40 °C may be obtained. Also these hydrocarbons may be burned or otherwise utilized.

The presented method, apparatus, system, and use enable the production of biofuel from torrefaction gas. Thus, the product variety of the torrefaction process increases, as the torrefaction gases are not necessarily burned. In contrast, the torrefaction gases can be used to produce biofuel. This enables more efficient use of the biomass feedstock, as excessive heat is not necessarily produced by burning the torrefaction gases.

As discussed, the apparatus for producing raw material for biofuel production, wherein the raw material is referred to as the torrefaction gas product, comprises a condenser arranged to condense torrefaction gases to a condensate. The apparatus for may further comprise means for separating water from the condensate. An apparatus for producing biofuel from torrefaction gases comprises means for producing the torrefaction gas product from the torrefaction gases, a hydrotreating unit, and a postprocessing unit, wherein the postprocessing unit is arranged to produce the biofuel. The apparatus may further comprise a torrefaction reactor arranged to torrefy biomass thereby producing the torrefaction gases.

As discussed, in the method, torrefaction gases are used to produce raw material for biofuel production, the raw material being referred to as the torrefaction gas product. Furthermore, at least part of the torrefaction gas product may be used to produce said biofuel. Alternatively or in addition, at least a part of torrefaction gas product may be sold and/or transported to another plant for the post processing.

Claims

Claims:

1 . A method for producing a torrefaction gas product (425) from torrefaction gases, wherein the torrefaction gas product (425) is suitable as raw material for biofuel production, the method comprising

- receiving torrefaction gases, the torrefaction gases being produced by processing biomass in a torrefaction process, and

- cooling the torrefaction gases to a condensing temperature to condense the torrefaction gases to a torrefaction gas condensate, wherein

- the condensing temperature is between 10 °C and 40 °C, whereby the torrefaction gas condensate comprises the torrefaction gas product (425).

2. The method of claim 1 , characterized in that the method comprises

- separating water from the torrefaction gas condensate to obtain the torrefaction gas product (425).

3. A method for producing a torrefaction gas product (425) from biomass, wherein the torrefaction gas product (425) is suitable as raw material for biofuel production, wherein the method comprises

- processing the biomass in a torrefaction process, the torrefaction process comprising treating the biomass in a temperature between 200 and 350 °C; to produce torrefaction gases, and

- performing the steps of the claim 1 or the claim 2.

4. A method for producing biofuel from torrefaction gases or biomass, characterized in that the method comprises

- receiving the torrefaction gas product (425) having been produced by the method of any of the claims 1 to 3, and

- hydrotreating at least part of the torrefaction gas product (425) in a hydrotreatment unit (200) comprising at least one hydrotreating reactor (530), with hydrogen, and using at least one catalyst;

to produce a biofuel mixture (560) comprising said biofuel.

5. The method of claim 4, characterized in that the method comprises - using at least a first catalyst, - the first catalyst being selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and

- the first catalyst being supported by a support material selected from the group comprising Al₂0₃, SiC, activated carbon, zeolite, zeolite-AI₂0₃, AI₂O₃-

Si0₂, and their combinations.

6. The method of claim 5, characterized in that method comprises using a second catalyst,

(a)

- the second catalyst being selected from the group of hydrodewaxing (HDW) and hydrodeoxygenating (HDO) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW and the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and

- the second catalyst being supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃- SiO₂, and their combinations,

or

(b)

- the second catalyst being selected from the group comprising Group VIII metals, such as Pd or Pt, and

- the second catalyst being supported by a support material selected from the group comprising SAPO-1 1 , SAPO-41 , ZSM-22, ZSM-23, ferrite, AI₂O₃, SiO₂, and their combinations.

7. The method of claim 5, characterized in that the method comprises using a mixture or a combination of the first catalyst and a second catalyst.

8. The method of any of the claims 4 to 7, characterized in that the method comprises

- hydrotreating the torrefaction gas product (425) such that the volumetric ratio of hydrogen to torrefaction gas product (425) ranges between 600 Nl/I and 4000 Nl/I.

9. The method of claim 8, characterized in that the method comprises

- determining a total mass of catalysts in the active reactor(s), rricataiystig], - determining a suitable torrefaction gas product (425) feed rate, Vf_eed[g/h], by the equation Vfeed[g/h]=WHSV[h^'1]xmcat_aiyst[g], and

- controlling a torrefaction gas product flow using the determined suitable torrefaction gas product (425) feed rate, wherein

- the WHSV (weight hourly spatial velocity) varies is in the range from 0.1 h^"1 to 5 h^"1.

10. The method of any of the claims 4 to 9, characterized in that the method comprises

- fractionating the biofuel mixture (560) to at least one biofuel compound.

1 1 . Use of a condenser (410), comprising

- using the condenser (410) for condensing torrefaction gases to a torrefaction gas condensate, by cooling the torrefaction gases to a condensing temperature, the condensing temperature being between 10 °C and 40 °C, the torrefaction gas condensate comprising a torrefaction gas product (425), wherein

- the torrefaction gases have been produced by processing biomass in a torrefaction process.

12. Use of claim 1 1 , comprising

- using the condenser (410) in connection with a separator (420), wherein

- the separator is arranged to separate water from the torrefaction gas condensate to obtain the torrefaction gas product (425).

13. Use of claim 1 1 or 12, comprising

- using the torrefaction gas product (425) as an input material in a hydrotreating process, wherein

- the hydrotreating process comprises treating the input material with hydrogen in a hydrotreatment unit (200) comprising at least one hydrotreating reactor (530), and using at least one supported catalyst;

to produce a biofuel mixture (560) comprising said biofuel.

14. An apparatus for producing a torrefaction gas product (425) from torrefaction gases, wherein the torrefaction gas product (425) is suitable as raw material for biofuel production, the apparatus comprising - means for receiving the torrefaction gases, and

- a condenser (410) arranged to cool the torrefaction gases to a condensing temperature, wherein

- the condensing temperature is between 10 °C and 40 °C, thereby condensing the torrefaction gases to a torrefaction gas condensate, wherein the torrefaction gas condensate comprises the torrefaction gas product (425).

15. The apparatus of claim 14, characterized in that the apparatus comprises

- a separator (420) arranged to separate water from the torrefaction gas condensate to obtain the torrefaction gas product (425).

16. The apparatus of claims 14 or 15, characterized in that the apparatus comprises

- a torrefaction reactor (300) arranged to thermally treat biomass or dried biomass in a temperature ranging between 200 and 350 °C, to produce torrefied biomass and the torrefaction gases.

17. The apparatus of any of the claims 14 to 16, the apparatus comprising - a hydrotreatment unit (200) comprising a hydrotreating reactor (530) arranged to treat the torrefaction gas product (425) with hydrogen and with at least one catalyst; to produce a biofuel mixture (560), and

- means for conveying the torrefaction gas product (425) to the hydrotreatment unit (200).

18. The apparatus of claim 17, characterized in that the hydrotreating reactor (530) comprises only one catalyst bed (534), and

(a)

- the catalyst bed comprises a catalyst, the catalyst being selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and

- the catalyst is supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃-SiO₂, and their combinations

or

(b) - the catalyst bed comprises a first catalyst and a second catalyst,

- the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo,

- the second catalyst is selected from the group of hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW,

- the first catalyst is supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃-SiO₂, and their combinations, and

- the second catalyst is supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃- SiO₂, and their combinations.

19. The apparatus of claim 17, characterized in that the hydrotreating reactor (530) comprises

- a first catalyst bed (534a) and a second catalyst bed (534b),

- the first catalyst bed (534a) comprises a first catalyst, wherein the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo,

- the first catalyst is supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃-SiO₂, and their combinations,

- the second catalyst bed (534b) comprises a second catalyst or a combination or a mixture of the second catalyst and another catalyst, and

(a) the second catalyst is selected from the group of hydrodewaxing (HDW) and hydrodeoxygenating (HDO) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW, and the group of hydrodeoxygenating (HDO) catalysts comprising CoMo and NiMo, and

the second catalyst is supported by a support material selected from the group comprising AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃- SiO₂, and their combinations,

or

(b) the second catalyst is selected from the group of hydroisomerization (HI) catalysts, the group of hydroisomerization (HI) catalysts comprising Group

VIII metals, such as Pd or Pt, and the catalyst is supported by a support material selected from the group comprising SAPO-1 1 , SAPO-41 , ZSM-22, ZSM-23, ferrite, Al₂0₃, Si0₂, and their combinations.

20. The apparatus of claim 17, characterized in that the hydrotreating reactor (530) comprises:

- at least two catalyst beds (534a, 534b),

- each catalyst bed comprises at least one of a first catalyst and a second catalyst,

- the first catalyst is selected from the group of hydrodeoxygenating (HDO) catalysts, the group of hydrodeoxygenating (HDO) catalysts comprising

CoMo and NiMo,

21 . The apparatus of claim 17, characterized in that the hydrotreatment unit (200) comprises

- a first hydrotreating reactor (530a) comprising a first catalyst bed (534a) comprising a first catalyst, wherein

- the first catalyst is supported by a support material selected from the group comprising of AI₂O₃, SiC, activated carbon, zeolite, zeolite-AI₂O₃, AI₂O₃-SiO₂, and their combinations_, and the hydrotreatment unit (200) further comprises

- a second hydrotreating reactor (530b) comprising a second catalyst bed (534b) comprising a second catalyst, and

(a) the second catalyst is selected from the group of hydrodewaxing (HDW) catalysts, the group of hydrodewaxing (HDW) catalysts comprising NiW, and the second catalyst is supported by a support material selected from the group comprising Al₂0₃, SiC, activated carbon, zeolite, zeolite-AI₂0₃, Al₂0₃-

Si0₂, and their combinations

or

(b) the second catalyst is selected from the group of hydroisomerization (HI) catalysts, the group of hydroisomerization (HI) catalysts comprising Group VIII metals, such as Pt, and the second catalyst is supported by a support material selected from the group comprising SAPO-1 1 , SAPO-41 , ZSM-22, ZSM-23, ferrite, Al₂0₃, Si0₂, and their combinations.

22. The apparatus of any of the claims 17 to 21 , characterized in that the apparatus comprises

- a fractionating unit (610) arranged to fractionate at least part of the biofuel mixture (560) to a fraction of the biofuel, and

- means for conveying the biofuel mixture (560) from the first or the second hydrotreating reactor (530, 530b) to the fractionating unit (610).

23. Raw material for biofuel production, characterized in that the raw material has been produced by the process of any of the claims 1 to 3.