NL2005716C2 - Torrefying device and process for the thermal treatment of organic material. - Google Patents

Description

Torrefying device and process for the thermal treatment of organic material Field of the invention

The invention relates to a torrefying device, especially for torrefying organic 5 material, and to a method for the thermal treatment of organic material, as well as to a material obtained by the method.

Background of the invention

Torrefying biomass or other organic materials is known in the art. Torrefaction is 10 a technique in which biomass is heated in the substantial absence of oxygen. By heating biomass up to about 200 to 300°C, its characteristics change in such as way that the biomass can be easily grinded, compressed and stored. Compression of the material results in an attractive, standardised solid bio fuel with a high energy density.

W02009039603 describes a system and method for removing liquid mist and 15 aerosol entrained in a process carrier gas stream in e.g. a fast pyrolysis process with a settling tank for collection of liquids, the settling tank containing liquid extracted from the gas stream, a liquid separator connected to the tank for further separating liquids from the stream; a downward tilting drain connected to the separator to permit the gas stream and the separated liquid to exit the separator and flow into a riser connected to 20 the settling tank such that it can discharge the collected liquid to the tank and simultaneously provide an exit to the treated gas flow.

W02008010717 describes a method for purifying a combustible gas that is contaminated with contaminants, such as tar and/or dust particles, comprises feeding oil to the contaminated gas. The oil evaporates through contact with the contaminated gas. 25 Said evaporated oil is condensed on a quantity of the contaminants in such a manner that said contaminants grow in size to form particles of increased size in the gas. An electric field between electrodes is applied, by means of which said particles of increased size are electrically charged and removed from the gas. The condensation of the oil takes place at a temperature above the water dew point of the contaminated gas. 30 This water dew point is preferably between 50-100 °C, in particular between 50-80 °C.

W02007078199 describes a process for treating biomass that contains an amount of residual moisture. The material is heated to a torrefying temperature in a low-oxygen atmosphere in the torrefaction reactor, the material being converted into a torrefied 2 material. The material with the contained residual moisture is essentially fully dried in a drying chamber by evaporation of residual moisture. The torrefaction reactor comprises a torrefying chamber, in which the torrefaction of this dried material is essentially carried out. The material is conveyed through the torrefaction reactor in a 5 transport direction. The drying of the material in the drying chamber is carried out by introducing into it a hot drying gas that flows through the drying chamber in co-current with the material. The torrefaction of the material in the torrefying chamber of the torrefaction reactor is carried out by introducing into it a hot torrefying gas that flows through the torrefying chamber of the torrefaction reactor in counter-current with the 10 material.

Summary of the invention

Torgas are gases and vapours released during the torrefaction of organic material, such as biomass, that is thermal treatment in the substantial absence of oxygen, 15 between typically 200 °C and 350 °C. The phrase “in the substantial absence of oxygen” especially indicates that the amount of oxygen is below explosion values. As will be clear to a person skilled in the art, this may depend upon temperature and pressure. Especially, the amount of oxygen in the gas phase is kept below 5 vol. %, such as below 2 vol.%, like less than 0.5 vol. %. Hence, the invention provides a 20 process for the thermal treatment (such as also further described below), wherein the amount of oxygen in the gas phase in the reaction chamber is (maintained) below 5 vol. %, such as below 2 vol.%. Likewise, the invention also provides a process for the thermal treatment wherein the amount of oxygen in the gas phase in the gas transport structure (such as also further described below) is (maintained) below 5 vol. %, such as 25 below 2 vol.%. The thermal treatment, here torrefaction, is especially performed at a temperature in the range of 200-320 °C, such as 220-300 °C. Hence, the invention provides a process for the thermal treatment (such as also further described below), wherein the organic material is thermally treated (torrefied) in a torrefying chamber at a temperature in the range of 200-320 °C, such as 220-300 °C. When employing counter-30 current flow in the torrefaction section, such as for instance suggested in W02007078199, the exothermicity of the torrefaction reaction can be controlled and good temperature control at acceptable gas flow rates can be achieved.

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High temperature torrefaction condensate (HTC) refers to those condensables in the torgas that condense above the boiling point of water, e.g. 100°C at atmospheric conditions. When the high-temperature torrefaction condensate is not removed, fouling may occur in the torrefaction reactor and/or in the gas transport structure connected to 5 the reactor.

Hence, it is an aspect of the invention to provide an alternative torrefying device and an alternative thermal treatment process, which preferably further at least partly obviate one or more of above-described drawbacks.

It is especially an aspect of the invention to reduce or prevent fouling caused by 10 the “high-temperature torrefaction condensate” (HTC) and ((subsequently) dust) to reduce or avoid the formation of water-HTC mixtures. It may further be an aspect to provide valuable HTC.

The inventors have found that HTC starts to condense at temperatures within a few degrees below the torrefaction temperature The HTC is unstable at high 15 temperatures, e.g. at atmospheric conditions typically between 100 and 250°C, and degrades from a low viscosity liquid to a carbonaceous solid. The speed of the degradation is slow at lower temperatures, taking days to weeks.

The process of the invention may be performed at atmospheric pressure, but also at elevated pressures. Hence, the invention also provides a process for the thermal 20 treatment (such as also further described below), wherein the organic material is torrefied in a torrefying chamber, wherein the pressure in the torrefying chamber is (maintained) at a pressure in the range of 0.5-20 bar, especially 0.5-5 bar, and more especially at near atmospheric pressure (for instance between -0.5 and +0.5 bar). Likewise, the invention also provides a process for the thermal treatment wherein the 25 pressure in the gas transport structure (such as also further described below) is (maintained) at a pressure in the range of 0.5-20 bar, especially 0.5-5 bar, and more especially at near atmospheric pressure.

An embodiment of the invention is that this torgas (from the torrefying chamber) is cooled indirectly, for instance by a cooling medium (typically a thermal oil) down to 30 a temperature above, and typically close to, the boiling point of water, for instance in a heat exchanger that may especially be designed in such a way (e.g., sufficiently vertical) that it allows a rapid draining of the HTC in a receiver, such as a vessel, which itself may be below the condensation temperature of water, with connecting pipework 4 preferably kept at temperatures high enough to allow the HTC to flow well (typically above 30 °C) and low enough to avoid rapid HTC degradation. It is preferred that gas cooling and condensate removal are combined with reheating the torgas to evaporate remaining condensate (aerosols) if these are not removed entirely. Optionally, the gas 5 cooling and condensate removal may be combined with a device to actively remove / separate condensate aerosols from the gas stream (aerosol separator), such as an electrostatic precipitation (ESP) filter, a demister, or other aerosol removers (known in the art).

The chamber(s) hosting or receiving the cooled torgas stream including 10 condensate (for instance in the form of a liquid film on the wall, of droplets and fine liquid and/or solid aerosols) may especially be designed such that the liquid can easily drain down and that droplets are not readily carried along by the gas stream.

A torgas recycle is advantageous in that it may readily yield a combustible gas. And removal of the HTC above the boiling point of water may avoid the condensation 15 of water, and the energy efficiency or waste water removal problems this entails.

Hence, in a first aspect, the invention provides a torrefying device comprising: a. a torrefying chamber configured to torrefy organic material, the torrefying chamber further comprising a torrefying chamber gas inlet for a gas and a torrefying chamber gas outlet for removal of torrefying chamber gas (also indicated herein as 20 “torgas”) from the torrefying chamber; b. a gas transport structure, connecting the torrefying chamber gas outlet with the torrefying chamber gas inlet, wherein the gas transport structure further comprises downstream from the torrefying chamber gas outlet and upstream of the torrefying chamber gas inlet a cooling chamber, comprising a cooling chamber opening for 25 removal of condensed liquid material, and downstream from the cooling chamber and upstream of the torrefying chamber gas inlet a heating chamber; c. a gas transport device configured to remove torrefying chamber gas via the torrefying chamber gas outlet from the torrefying chamber and configured to transport torrefying chamber gas through the gas transport structure back to the torrefying 30 chamber via the torrefying chamber gas inlet.

The torrefying device may consist of (though not limited to) several items, such as a drying chamber and a torrefying chamber, such as for instance described in W02007078199, which is herein incorporated by reference.

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In this invention, the torrefying device at least comprises a torrefying chamber. For instance, the device may comprise a torrefying reactor comprising such torrefying chamber. In an embodiment, the torrefying device may also comprise a plurality of torrefying chambers.

5 The term "organic material" may for instance refer to biomass, or organic material containing waste, (agricultural) residues, etc.

In the untreated state, many of such organic materials may be relatively wet. The material generally contains free (unbound) and (loosely) bound water. The bound or loosely bound water is absorbed by the natural raw material itself. For example, 10 biomass of plant origin, such as prunings and mown grass, contains a considerable amount of moisture by nature.

Furthermore, biomass can be very wet as a result of washing it or subjecting it to an alternative water treatment in order to reduce the salt content of the biomass. The organic material may for instance have a moisture content of 5-15%, i.e. an amount of 15 residual moisture is contained in the material.

The organic material with the residual moisture is introduced into the torrefaction reactor (i.e. in the reaction chamber of the reactor). Torrefaction is a thermo chemical treatment method for material. In this method the material is heated in a low-oxygen (with sub stoichiometric quantities of oxygen) or oxygen-free gaseous atmosphere, 20 usually though not necessarily under atmospheric pressure to a temperature of 200-350 °C, preferably 200-350 °C, even more preferably 200-300 °C. The lack of oxygen prevents the material from burning (see also above). Instead the material is torrefied, which leads to loss of mass because of the elimination of gases. This loss of mass generally amounts to about 10-50%, typically 30%, while the energy value is only 25 reduced by 5-20%, typically 10%. The fuel produced by torrefaction therefore has a higher calorific value.

Hence, herein torrefying the organic material may especially include heating the organic material, in the absence of an external oxygen feed, to a temperature selected from the range of 200-350°C, preferably 200-320 °C, especially 200-300 °C. In 30 general, the torrefying chamber (and drying chamber) is (are) flushed with a gas substantially free of oxygen, such as CO2, N2, steam and/or recirculated process gases. As indicated above, the torrefying chamber, but also the gas transport structure may be 6 kept at a pressure in the range of - 0.5 to + 20 bar, especially - 0.5 to +5 bar, and in general at near atmospheric pressure.

Torrefaction also causes changes to the chemical structure of the material. The material loses its mechanical strength and elasticity, so it is much easier to grind.

5 Furthermore, torrefied material is hydrophobic, and it therefore stays dry and is insensitive to atmospheric humidity. The risk of rotting and overheating is very small when the material which has been produced by torrefaction is stored.

The temperature of the material is raised in the torrefaction reactor. Before torrefaction of the material can take place, the residual moisture, however, evaporates 10 from the material. The material may be virtually completely dried, for instance in a drying chamber of the torrefaction reactor by evaporating the residual moisture. The actual torrefaction of the material may only take place after the residual moisture has been evaporated. Torrefaction may begin as soon as the temperature of the material exceeds about 200 °C. The torrefying temperature is, however, generally higher, being 15 about 250 °C. The temperature is especially selected to be above the dewpoint of at least water in the gas phase. The temperature in the torrefying chamber may vary locally. Preferably, the temperature in the entire torrefying chamber is maintained at at least 200 °C. Hence, the gas inlet temperature is at least 200 °C, preferably at least 230 °C, depending on the structure of the biomass and the exothermicity of the torrefaction 20 reactions.

The torrefying chamber allows transport of the organic material through the torrefying chamber (in a “first direction” or “transport direction”). The organic material may be transported under influence of gravity and/or may be transported by using a feed device, such as a screw. The torrefying chamber will thus have an entrance part, 25 where the (dried) organic material enters the reactor and an exit part, where the (torrefied) organic material leaves the reactor.

Herein the torrefying chamber at least may comprise (additionally), an inlet for a gas, and an outlet for a gas (i.e. the torgas from the torrefying chamber). The former is herein indicated as torrefying chamber gas inlet, through which gas can enter the 30 torrefying chamber, and the latter is herein indicated as torrefying chamber gas outlet, through which gas may escape from the torrefying chamber. The inlet and outlet are, in an embodiment, connected with the gas transport structure, which may comprise one or 7 more conduits for transporting gas (At the end of this section, embodiments are described wherein the inlet and outlet are not connected via the gas transport structure).

As indicated above, the gas transport structure comprises a cooling chamber and a heating chamber, wherein the cooling chamber is downstream from the torrefying 5 chamber gas outlet, the heating chamber is downstream from the cooling chamber and upstream of the torrefying chamber gas inlet. In this way, recycling may be performed of the gas in the torrefying chamber. The cooling chamber is configured to cool torrefying chamber gas that has been removed from the torrefying chamber via the torrefying chamber gas outlet and has been transported through the gas transport 10 structure to the cooling chamber. The heating chamber is configured to heat the gas that has been cooled in the cooling chamber and that has been transported via a gas transport device (such as a pump, a blower, a fan, a compressor, etc.) to the heating chamber (through the gas transport structure). Especially, the heating chamber is configured to heat the gas to a temperature substantially equal to the chosen torrefying 15 chamber gas inlet temperature. In an embodiment, the gas transport structure may comprise a further heater, for instance arranged downstream of the heating chamber (but upstream of the torrefying chamber gas inlet. In embodiments wherein in addition to the heating chamber, a further heater (which may be a second heating chamber) is applied, the heating chamber and further heater are configured to heat the gas to a 20 temperature substantially equal to the chosen torrefying chamber gas inlet temperature. Hence, gas retrieved from the torrefying chamber is transported through the gas transport structure, and thereby flows through the cooling chamber and heating chamber, respectively, back to the torrefying chamber. The cooling chamber and the heating chamber may be separate chambers with different outlets, but may in an 25 embodiment also be two zones of a single device with different as well as equal outlets. In an embodiment, thermal energy released by the cooling chamber is used to heat the heating chamber.

The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of material, wherein relative to a first position 30 within a flow of material, a second position in the flow of material closer to a source of the material is “upstream”, and a third position within the flow of material further away from the source of material is “downstream”.

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During the recycle, the gas is treated. Condensables are condensed from the gas in the cooling chamber. The gas thus obtained from the cooling chamber is then heated again in the heating chamber (and by one or more optional downstream heaters) to reach a temperature suitable for introduction into the torrefying chamber.

5 Herein, cooling may comprise cooling to a cooling temperature selected from the range of higher than the dew point of water and lower than the torrefying temperature in the torrefying chamber. In general, the cooling temperature will be above the condensation temperature of water, and preferably below about 200 °C. For instance, the cooling temperature may be selected from the range of 110-180 °C, such as about 10 120-140 °C; this may especially apply at atmospheric conditions. At pressurised conditions, the selected temperature may be higher.

Herein, heating comprises heating to a temperature above the cooling temperature. Preferably, heating (in the heating chamber, and by one or more optional downstream heaters) includes heating to a temperature of at least 200 °C, especially at 15 least 230 °C. The subsequent heating may allow aerosols that may not have been removed as liquid from the cooling chamber (and the heating chamber), to be evaporated and kept at a high enough temperature that they will not deposit somewhere downstream in the gas transport structure. In this way, the torrefying chamber gas is reduced in condensables during transport through the gas transport structure (i.e. 20 especially in the cooling chamber), and the gas reduced in condensables is reintroduced into the torrefying chamber.

In a specific embodiment, the cooling chamber comprises a heat exchanger configured to facilitate cooling of the torrefying chamber gas. For instance, the heat exchanger may be cooled with thermal oil.

25 In a specific embodiment, the heat exchanger may further be configured to facilitate transport of liquid material to the cooling chamber opening. For instance, the heat exchanger may comprise substantially vertically cooling elements. Alternatively or in addition, the cooling chamber is configured to facilitate transport of liquid material to the cooling chamber opening. For instance, the cooling chamber may have smooth 30 walls, and the walls may be arranged to facilitate transport to the cooling chamber opening. For instance, at least part of the cooling chamber may have the shape of a funnel, with preferably the cooling chamber opening at the bottom of the funnel.

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Also the heating chamber may comprise a heating chamber opening for removal of liquid material. Condensables in the heating chamber may in this way be removed. Further, the heating chamber may comprise a heat exchanger configured to facilitate heating of the torrefying chamber gas. For instance, to facilitate that condensed 5 material may escape via the heating chamber opening and not leave the heating chamber with the flow (further into the gas transport structure), the heat exchanger may comprise substantially vertically heating elements. Further, the heating chamber may be configured to facilitate transport of liquid material to the heating chamber opening. For instance, the heating chamber may have smooth walls, and the walls may be 10 arranged to facilitate transport to the heating chamber opening. For instance, at least part of the heating chamber may have the shape of a funnel, with preferably the heating chamber opening at the bottom of the funnel.

The torrefying device may further comprise a receiver, arranged to receive liquid from the cooling chamber and optionally arranged to receive liquid from the heating 15 chamber. The receiver may act as a gas liquid separating device separating liquid droplets and/or aerosols from the gas stream. The receiver may be an integral part of the torrefying device or may be a removable receiver. The receiver may further be connected (with pipework/conduits) with a storage vessel. Alternatively, the receiver may be connected (with pipework/conduits) with a furnace for incineration of the liquid 20 material that is received from the cooling chamber (and from the heating chamber).

The torrefying device may further comprise a temperature regulator, configured to control the temperature of the receiver. In this way, this may allow maintaining the receiver at a temperature of at least 30 °C and below a temperature at which the HTC might be unstable. For instance, this may imply in an embodiment maintaining the 25 receiver at a temperature of at least 30 °C and below 100 °C.

As will be clear to a person skilled in the art, the entire gas transport may be heated to the (locally) desired temperature. For instance, up to the cooling chamber (i.e. upstream of the cooling chamber), the gas transport structure may be kept at a temperature of over 200 °C, such as about 230 °C. Likewise, the gas transport 30 downstream of the heating chamber may be kept a temperature of over 200 °C, such as about 230 °C (preferably at about the same temperature as the chosen torrefying chamber gas inlet temperature).

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If desired, part of the gas in the gas transport structure may be removed and may for instance be fed to a combustion unit. Thermal energy of this combustion unit may again be used for heating the torrefying chamber, the optional drying chamber, for heating the heating chamber, etc.

5 In a specific embodiment, the torrefying device is configured to allow transport of organic material in a first direction (transport direction) and the torrefying chamber gas inlet and the torrefying chamber gas outlet are arranged to facilitate a counter-current flow of the torrefying chamber gas. The gas transport device (such as a pump, a blower, a fan, a compressor, etc.) facilitates the counter-current flow of the gas in the 10 torrefying chamber. An advantage of the counter-current flow may be a good control of the torrefying temperature. As indicated above, the organic material flow may for instance be obtained under influence of gravity and/or under influence of a feed device. Hence, in a further embodiment, the torrefying device may comprise a feed device configured to transport the organic material through a torrefying reactor comprising the 15 torrefying chamber. The feed device may also be applied to transport the organic material through a drying chamber (see also below). In an embodiment, the organic material can move from the top downwards within torrefying chamber under the influence of gravity. However, it may in an embodiment also be possible for the organic material to flow through the torrefaction reactor from below upwards. For this 20 purpose the feed device, as indicated above, may be provided, for example, such as a screw member or a piston which can move up and down within the torrefying chamber. Further, the torrefying chamber may comprise internals for facilitating transport. For instance, the torrefying chamber may comprise trays.

In a specific embodiment, the feed device may comprise two pistons and a 25 supporting valve. The first piston can move through an inlet to push in organic material for the second piston, which can move up and down within the torrefying chamber. The supporting valve can move between a supporting position and a free position. When the piston has reached the end of its stroke, the supporting valve moves over to the supporting position to support the organic material within the torrefying chamber. The 30 second piston can then move downwards, after which the first piston can again load a quantity of organic material on it. However, the feed device can also be designed as a conveyer screw. The design of the feed device may depend on the orientation of the 11 torrefying chamber, which can be essentially vertical, horizontal or inclined at an angle between the two.

The reactor may in an embodiment also be a moving bed reactor. In such embodiment, the organic material should preferably comprise solid particles that are 5 passed through the torrefying chamber in the form of a packed moving bed. In this case the torrefying device is operated on the principle of moving-bed technology.

In a further aspect, the invention provides a process for the thermal treatment of organic material, the process comprising: a. torrefying the organic material in a torrefying chamber of a torrefying 10 device; b. removing torrefying chamber gas from the torrefying chamber, subjecting the removed torrefying chamber gas to a treatment, and after treatment reintroducing the treated torrefying chamber gas into the torrefying chamber, wherein the treatment comprises a cooling and a subsequent heating; 15 c. maintaining a, preferably counter-current, flow of the torrefying chamber gas, relative to a flow of the organic material through the torrefying chamber.

As indicated above, the process may further comprise receiving liquid material from the cooling chamber and optionally from the heating chamber in a receiver.

Especially, the torrefying device as described herein may be applied to execute 20 the process.

According to yet a further aspect, the invention provides a condensate, mainly originating from the lignin fraction in the biomass. This high temperature condensate may have a calorific value significantly higher than the original feedstock, typically between 30 and 35 MJ/kg, and an elemental composition similar to the elemental 25 composition of lignins. It has a high solubility in ethanol or glycerol and less high solubility in water or hydrocarbon liquids such as diesel. Evaporation of the condensate is only possible without substantial carbonaceous remainder, if it is in the form of aerosols below about 1 micron in diameter. The condensate is not stable, especially so at elevated temperatures. For atmospheric conditions, at 100 °C mass loss of around 15 30 % may occur over a week. At temperatures exceeding 200 °C the condensate may rapidly degrade leaving a carbonaceous residue behind, unless the condensate liquid is in the form of aerosols.

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When quantities above a few gram are heated to a temperature that causes rapid degradation, gases that are released cannot readily escape the degrading liquid and blow it up into a foam resulting in a very low density char, that is a density below 50 g/1 and sometimes below 20 g/1. The PAH (polyaromatic hydrocarbons) content of the 5 condensate is typically below 1 ppm and therefore significantly lower than for lignin fragment rich condensate products from slow or fast pyrolysis known in the art. The viscosity of condensate that has not been significantly degraded approaches that of water at a temperature of 100 °C and is comparable to honey in the temperature range 0 to 40 °C.

10 A considerable amount of steam may be generated in the torrefaction reactor when residual moisture is evaporated in the torrefaction reactor. This can lead to a relatively fast-moving gas stream flowing in the reactor, which increases the pressure drop over the reactor. Furthermore, the energy needed for evaporating the residual moisture may be much greater than the energy required for torrefaction. In particular, in 15 a torrefaction reactor based on direct contact between the gas and the material, a relatively large amount of hot gas may have to be introduced into the torrefaction reactor at a high inlet temperature, which may further increase the amount of gas that has to pass through the torrefaction reactor. This may hamper the implementation of the method of treatment.

20 Hence, in a specific embodiment, the torrefaction reactor may comprise a drying chamber and a torrefying chamber, the organic material with the residual moisture contained in it being essentially fully dried in the drying chamber by evaporation of the residual moisture, and the torrefaction of the dried material being essentially carried out in the torrefying chamber, and the material being conveyed through the torrefaction 25 reactor in a transport direction, and the drying of the material in the drying chamber being carried out by introducing into it a hot drying gas that flows through the drying chamber in co-current with the material, and the torrefaction of the material in the torrefying chamber of the torrefaction reactor being carried out by introducing into it a hot torrefying gas that flows through the torrefying chamber of the torrefaction reactor 30 in counter-current to the material.

According to an embodiment of the invention, the material is dried in the drying chamber, after which the material is torrefied in the torrefying chamber. The drying chamber and the torrefying chamber form in an embodiment two separate spaces here.

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In an embodiment, the evaporation of residual moisture from the material and the torrefaction of the material therefore may form two separate stages, each of which can be optimized.

The organic material may almost be fully dried in the drying chamber, which may 5 require a relatively large amount of energy. The evaporation of residual moisture from the material may be efficient, because in an embodiment the material and the hot gas move in co-current with each other. The drying chamber is designed specifically for the drying of the material.

When a hot gas is introduced, which is e.g. in direct contact with the material, the 10 temperature of the material in the torrefaction reactor may rise to a torrefying temperature. Since this hot gas may in an embodiment flow in counter-current to the organic material, the temperature of the hot gas "follows" the temperature of the material. The temperature of the material and the temperature of the hot gas both increase in the transport direction of the material. The inlet temperature of the hot gas 15 then is close to, and often slightly below, the temperature of the material due to the counter-current flow arrangement and the exothermicity of the torrefaction reaction. By controlling flow and inlet temperature of the hot gas, there is only a very small risk of "hot spots" developing in the dry material, or of uncontrolled torrefaction or pyrolysis taking place. Initially, only a relatively small amount of energy needs to be introduced 20 into the torrefying chamber, which allows for an improved dosing and/or fine tuning of the energy input. As a result, the torrefying temperature in the torrefying chamber can be set and controlled accurately.

A further advantage of the invention may be that the required temperatures of the hot gases introduced - drying gas and torrefying gas - are relatively low. This facilitates 25 the production of these hot gases. For example, the temperature of the hot gas introduced into the torrefying chamber is in the range of 200-400 °C, being e.g. about 300 °C, or being about at least 230 °C. Controlled torrefaction can be carried out in the torrefying chamber at such a temperature. In addition the temperature of the hot gas introduced into the drying chamber can be in the range of 150-600 °C though 30 depending on pressure levels, being e.g. about 350 °C. This temperature is particularly suitable for the almost complete drying of the material, such as to a moisture content of < 3%. These temperatures are sufficiently low for the production using e.g. thermal oil.

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When the drying chamber and the torrefying chamber are accommodated in the torrefaction reactor, the drying chamber and the torrefying chamber form two reaction spaces of the torrefaction reactor. The drying of the material by evaporation of the residual moisture may essentially be carried out in the first reaction space, i.e. the 5 drying chamber, and the torrefaction of the material may essentially be carried out in the second reaction space, i.e. the torrefying chamber. The organic material may in fact almost completely dried here by evaporation of the residual moisture in the torrefaction reactor, but the process in the torrefaction reactor is separated according to the invention into two stages, each of which can be optimized.

10 However, it is also possible according to the invention to house the drying chamber in a residual-moisture dryer, and to house the torrefying chamber in the torrefaction reactor. In this case, the residual-moisture dryer forms a separate device, which is housed separately from the torrefaction reactor. The residual-moisture dryer can be so designed as to ensure the efficient evaporation of the residual moisture from 15 the material. The residual-moisture dryer is connected with the torrefaction reactor for the transfer of the almost fully dried material from the residual-moisture dryer into the torrefying chamber.

It is possible according to the invention for the drying gas, after it has moved in co-current with the material and has thus been cooled to leave the drying chamber and 20 to be introduced into a first heat exchanger, which heats up this drying gas, after which the drying gas heated up by the first heat exchanger is introduced into the drying chamber, and the torrefying gas after it has moved in counter-current to the material and has thus been cooled down leaving the torrefying chamber and being introduced into the cooler/heater system to remove the HTC and a second heat exchanger 25 (especially the heat exchanger in the heating chamber), which heats up this torrefying gas, after which the torrefying gas that has been heated up by the second heat exchanger is introduced into the torrefying chamber. In this case, the drying gas circulates in a first circuit, while the torrefying gas circulates in a second circuit (here indicated also as “gas transport structure”). By using two circuits, each with its own 30 heat exchanger, it is possible to ensure an efficient energy recovery from the drying gas and the torrefying gas.

In particular, the provision of the material by the process according to an embodiment of the invention comprises introducing a relatively wet raw material into a 15 dryer, and heating the material in the dryer to evaporate moisture from the material until the amount of residual moisture stays in it, the material that has been dried in the dryer being introduced into the drying chamber. The relatively wet material has a moisture content of e.g. more than 15%. The relatively wet material can then be 5 thermally dried in a dryer, such as a rotating-drum dryer before being introduced into the drying chamber of the torrefaction reactor or the residual-moisture dryer. As the material is warmed in the dryer, the temperature rises sufficiently to evaporate moisture from the material. The material is not fully dried in the dryer, i.e. an amount of residual moisture is left in the material. The residual moisture is mainly formed by bound water 10 in the material. In practice, energy is introduced into the dryer until the moisture content of the material is about 10-15%. The biomass is then 85-90% dry. Reducing the moisture content in the dryer further might reduce the yield of the whole treatment method. For example, the dryer is not suitable for drying the material further in an economically efficient manner.

15 Incidentally, material with moisture content higher than 15% can of course also be fed into the torrefaction reactor without preliminary drying or pre-drying in a separate dryer. For example, straw generally has a moisture content of about 20%. This straw can be directly fed into the torrefaction reactor according to the invention without preliminary drying. The drying of that straw then takes place completely in the drying 20 chamber of the torrefaction reactor according to the invention. Conversely, it may sometimes be desirable first to pre-dry in the dryer material that only contains a relatively small amount of moisture, such as 5% or less.

The material according to an embodiment of the invention should preferably contain solid particles that are passed through the torrefaction reactor in the form of a 25 packed moving bed. In this case the torrefaction reactor is operated on the principle of moving-bed technology.

The invention also provides in an embodiment a specific device for treating material, comprising a torrefaction reactor, to which material can be fed which contains an amount of residual moisture, which torrefaction reactor is provided with an inlet for 30 introducing this material into the torrefaction reactor, heating means for heating the material in the torrefaction reactor to a torrefying temperature, air-treating means for creating a low-oxygen environment (with substoichiometric quantities of oxygen) in 16 the torrefaction reactor wherein the material can be converted into torrefied material during operation, and an outlet for removing torrefied material.

According to an embodiment of the invention, the torrefaction reactor comprises a drying chamber and a torrefying chamber, which drying chamber is adapted for the 5 essentially complete drying of the material by evaporating the residual moisture and which torrefying chamber is adapted for torrefying the material, and wherein the torrefying chamber is located downstream of the drying chamber when viewed in the direction of flow of the material, and wherein the drying chamber has at least one inlet orifice for drying gas and at least one outlet orifice for the said drying gas and any gas 10 and/or vapour formed during evaporation of residual moisture, which inlet orifice for drying gas is located at the end of the drying chamber that faces the inlet and the outlet orifice is located at the opposite end of the drying chamber, and wherein the torrefying chamber has at least one inlet orifice for torrefying gas and at least one outlet orifice for said torrefying gas and torrefaction gas formed in the torrefaction process, which inlet 15 orifice for torrefying gas is located at the end of the torrefying chamber that faces the outlet and the outlet orifice is located at the opposite end of the torrefying chamber.

The drying gas and the torrefying gas are both hot gases. The hot drying gas is intended for evaporating residual moisture in the drying chamber, while the hot torrefying gas is intended for heating the almost completely dry material in the 20 torrefying chamber to the required torrefying temperature. Combustible torrefaction gases are formed during the torrefaction process in the torrefying chamber and can be removed through the outlet orifice. The drying gas and the torrefying gas can be treated both as separate streams with different water dewpoints as well as a mixed stream with a generally higher water dewpoint and lower HTC dewpoint than the torrefying gas 25 itself.

During operation, the material is conveyed through the torrefaction reactor in a transport direction. The material is dried in the drying chamber by the introduction of a hot drying gas into it through one or more inlet orifices in the drying chamber. The hot drying gas flows through the drying chamber in co-current with the material. The 30 torrefaction of the material in the torrefying chamber of the torrefaction reactor is carried out by introducing into it a hot torrefying gas through one or more inlet orifices in the torrefying chamber. The hot torrefying gas flows through the torrefying chamber of the torrefaction reactor in counter-current to the material. The drying gas and the 17 torrefying gas flow towards each other from opposite ends of the torrefaction reactor. These gases meet each other at the outlet orifices located between the drying gas inlet orifices and the torrefying gas inlet orifices. This ensures a gas separation between the drying chamber and the torrefying chamber. The drying chamber and torrefying 5 chamber are located at opposite ends of the gas separation - the gas separation delimits the drying chamber and torrefying chamber with respect to each other. Unlike in the prior art, where the material can be almost fully dried by evaporation of the residual moisture in the torrefaction reactor, the process in the device according to the invention can be split into two stages which can be set in an optimum manner.

10 When the drying chamber and the torrefying chamber are housed in the torrefaction reactor, the drying chamber and the torrefying chamber may form two separate spaces in the same torrefaction reactor. In an alternative embodiment the drying chamber is located e.g. in a residual-moisture dryer, and the torrefying chamber is located in the torrefaction reactor. In this case, the residual-moisture dryer forms a 15 separate entity, which is housed separately with respect to the torrefaction reactor. It is possible according to the invention to provide a dryer to which a relatively wet material can be supplied, which dryer has heating means to warm this material in order to evaporate some or most of the moisture from the material and the material dried in the dryer being able to be fed into the drying chamber of the torrefaction reactor. This 20 makes the device according to the invention suitable for handling relatively wet material, for example material with a moisture content of about 15%, 25% or more. The relatively wet material can be thermally pre-dried in the dryer before it is fed into the torrefying chamber.

The device according to the invention can therefore comprise two dryers and a 25 torrefying chamber. The first drier forms a preliminary dryer that is used to reduce the moisture content to e.g. about 5-15%. The second dryer is formed by the drying chamber in the torrefaction reactor or by the residual-moisture dryer as described above.

In one embodiment of the invention, the torrefaction reactor is bounded by a 30 peripheral wall, the drying chamber and the torrefying chamber extending as a continuation of each other within the peripheral wall. When viewed in the direction of flow of the material, the drying chamber is located between the inlet for material and 18 the torrefying chamber, and the torrefying chamber is located between the drying chamber and the outlet for torrefied material.

In one embodiment of the invention, the torrefaction reactor is mounted in the upright position, a number of inlet orifices being provided in the peripheral wall, one 5 above the other, for drying gas. This torrefaction reactor can be e.g. vertical or it can be erected at an angle. Since these orifices are distributed around the periphery of the peripheral wall, the gas can penetrate to the material which is located centrally within the peripheral wall. The material is given sufficient opportunity for drying over its entire cross section within the peripheral wall.

10 The material can move from the top downwards within the peripheral wall under the influence of gravity. However, it is also possible for the material to flow through the torrefaction reactor from below upwards (or in an embodiment horizontally). For this purpose a feed device is provided, for example, such as a screw member or a piston which can move up and down within the peripheral wall. The feed device can be 15 located outside the hot peripheral wall of the torrefaction reactor. The thermal load of the feed device is thereby reduced.

In one embodiment of the invention, the outlet is connected to a cooling chamber and the torrefied material can be introduced from the torrefying chamber into the cooling chamber. For example, the feed device pushes the material within the 20 peripheral wall of the torrefaction reactor upwards until the material reaches an overflow part. The torrefied material overbalances along the edge of the overflow part and drops beyond it into the cooling chamber. The cooling chamber is generally provided with inlet orifices for cooling gas. The cooling gas cools the torrefied material.

25 The liquid material obtained after cooling is of interest and may be used for several purposes. Also the remaining gas may be of interest. As indicated above, it may be reused, and introduced (after heating) to the torrefying chamber, whereas the produced torgas is taken out of the loop and combusted in a combustor However, in an alternative embodiment, the remaining gas is used per se, and not reintroduced in the 30 torrefying chamber. For instance, the gas obtained may be fed to an after burner, or may be used in other applications, e.g. (co)firing in boilers or prime movers. Hence, in a further aspect, the invention provides a torrefying device comprising: 19 a. a torrefying chamber configured to torrefy organic material, the torrefying chamber further comprising a torrefying chamber gas inlet for a gas and a torrefying chamber gas outlet for removal of torrefying chamber gas from the torrefying chamber; b. a gas transport structure, wherein the gas transport structure further 5 comprises downstream from the torrefying chamber gas outlet a cooling chamber, comprising a cooling chamber opening for removal of condensed liquid material, and downstream from the cooling chamber optionally a heating chamber; c. optionally a gas transport device configured to remove torrefying chamber gas via the torrefying chamber gas outlet from the torrefying chamber and configured 10 to transport torrefying chamber gas through the gas transport structure (at least through the cooling chamber and optionally also through the heating chamber).

The remaining gas after the cooling chamber may used. If the heating chamber is available, the remaining gas after the heating chamber may be used. Optionally, remaining gas after the optional gas transport device may be used. The presence of the 15 optional heating chamber and optional gas transport device may depend upon the desired application and upon the pressure within the torrefying chamber.

The cooling and heating may be as defined above for the embodiments including the gas transport structure with gas loop back into the torrefying chamber.

Within this aspect, the torrefying device may further comprise an additional gas 20 source, configured to provide torrefying gas into the torrefying chamber.

In a further aspect, the invention also provides a process for the thermal treatment of organic material comprising: a. torrefying the organic material in a torrefying chamber of a torrefying device; 25 b. removing torrefying chamber gas from the torrefying chamber, subjecting the removed torrefying chamber gas to a treatment, and after treatment removing the remaining gas for further use, wherein the treatment comprises a cooling and optionally a subsequent heating.

The term “substantially” herein, will be understood by the person skilled in the 30 art in that it may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 20 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of’.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for 5 describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices herein are amongst others described during operation. As will be 10 clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In 15 the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may 20 be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Brief description of the drawings 25 Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figure 1 schematically depicts an embodiment of the device;

Figure 2 schematically depicts specific embodiment of the cooling chamber and 30 the heating chamber;

Figure 3 schematically depicts a specific embodiment of the device in cross section; and 21

Figure 4 schematically depicts another embodiment of the device of the invention.

Description of preferred embodiments 5 Figure 1 schematically depicts an embodiment of the torrefying device, indicated with reference 1. The torrefying device 1 comprises a torrefying reactor 10. The torrefying reactor 10 at least comprises a torrefying chamber 55. Upstream of the torrefying chamber 55, within the torrefying reactor and/or upstream of the torrefying reactor 10, optionally a drying chamber 54 may be provided (see also below). The feed 10 direction of the organic material, indicated with reference 301, is indicated with reference 302.

The torrefying device 1 further comprises a gas recycle loop or gas transport structure 330, which can be used to remove gas from the torrefying chamber 55, treat the gas, and if desired reintroduce the treated gas into the torrefying chamber 55. To 15 this end, the torrefying chamber (also) comprises a torrefying chamber gas outlet, indicated with reference 322, and a torrefying chamber gas inlet 321. The gas flow in the gas transport structure 330 and with the torrefying chamber 55 is indicated with reference 312. As can be seen, in this embodiment, the organic material flow 302 and the gas flow 321 are counter-current. The wall of the torrefying chamber 55 is indicated 20 with reference 50. As indicated herein, counter-current may be beneficial, but the invention also relates to embodiments with co-current flows 302,321. Preferably, the temperature of the gas at inlet 321 is at least 200 °C, more especially at least 320 °C.

The gas transport structure 330 comprises a cooling chamber 340 and downstream thereof a heating chamber 350. Due to the cooling, liquid may be formed 25 such as indicated above, which may be received from the cooling chamber (and optionally also (partly) from the heating chamber 350. The liquid may form in the chamber(s) and be collected in a receiver 360. Further, the torrefying device 1 comprises a gas transport device 370, configured to provide the gas flow 312 as indicated herein.

30 In an embodiment, the gas transport structure 330 may comprise one or more additional heaters 358, arranged downstream of the heating chamber 350, and upstream of the torrefying gas inlet 321. One or more additional heaters 358 may be arranged 22 upstream or downstream or heaters may be arranged upstream and downstream of the gas transport device 370.

Further, in an embodiment, the gas transport structure may comprise one or more additional devices 359 to remove aerosol particles. Those devices 359 are in general 5 arranged downstream of the cooling chamber 340 and upstream of the gas transport device 370. Characteristic locations have been indicated in the schematic drawing. The additional device(s) 359 to remove aerosol particles may for instance comprise electrostatic precipitation filter(s).

Figure 2 schematically depicts specific embodiment of the cooling chamber 340 10 and the heating chamber 350, respectively. Smooth funnel like walls 342,352, respectively, facilitate removal of liquids from the chambers 340,350, respectively. The chambers 340,350 have chamber openings 341,352, respectively, arranged at a lowest point of the respective chambers 340,350. In this way, liquid may be removed under influence of gravity. Liquid, i.e. condensed material, 401 may be collected in the 15 receiver 360. The receiver 360 may be kept at such a temperature, for instance by a temperature regulator 380, that the condensed material 401 stays viscous enough for transport, and does not (partly) degrade into solid material. Heat exchangers 345,355 may be used to cool and heat, respectively. Cooling elements 346 and heating elements 356 may be arranged substantially vertical. Also in this way, material that condenses 20 into liquid, may easily drop and reach the chamber outlets 341,351, respectively.

Further, the gas transport structure 330 may have an opening to remove gas and to feed the gas to for instance a combustion unit. Alternatively or additionally, the torrefying chamber 55 may comprise such opening.

A specific embodiment of the reactor is schematically depicted in figure 3. The 25 torrefaction reactor 10 comprises at least two reactor spaces. The first reactor space provides the drying chamber, while the second reactor space forms the torrefying chamber.

The torrefaction reactor 10 is in an embodiment essentially in the vertical position when it is in operation. The torrefaction reactor 10 comprises a peripheral wall 50, a 30 bottom section 51 and a top section 52. The inlet 11 for introducing biomass into the torrefaction reactor 10 is located at one side of the bottom section 51. The bottom section 51 comprises a feed device 53 for conveying the biomass upwards within the 23 peripheral wall 50. The feed device 53 is shown schematically in Fig. 3. The peripheral wall 50 in the torrefaction reactor is filled with biomass during operation.

The feed device 53 can have various designs. For example, the feed device comprises two pistons and a supporting valve. The first piston can move through the 5 inlet 11 to push in biomass for the second piston, which can move up and down within the peripheral wall. The supporting valve can move between a supporting position and a free position. When the piston has reached the end of its stroke, the supporting valve moves over to the supporting position to support the biomass within the peripheral wall. The second piston can then move downwards, after which the first piston can 10 again load a quantity of biomass on it. However, the feed device can also be designed as a conveyer screw. The design of the feed device 53 depends on the orientation of the torrefaction reaction, which can be essentially vertical, horizontal or inclined at an angle between the two.

Within the peripheral wall 50, the torrefaction reactor 10 is divided into a first 15 reaction space or drying chamber 54 for the evaporation of residual moisture from the biomass, and a second reaction space or torrefying chamber 55 for torrefaction of the biomass. In this exemplary embodiment, there is no physical separation between the drying chamber 54 and the torrefying chamber 55 and the reaction spaces 54 and 55 are continuous. The transition between the reaction spaces 54 and 55 is indicated by the 20 dashed line C. In this exemplary embodiment, the drying chamber 54 and the torrefying chamber 55 are therefore not enclosed chambers but form a continuous drying space 54 and torrefying space 55.

The drying chamber 54 is therefore located between the biomass inlet 11 and the torrefying chamber 55. The drying chamber 54 has a number of inlet orifices 12a for 25 the introduction of a hot drying gas. The drying gas introduced has a temperature of e.g. 100-400 °C. The drying gas and the biomass move in co-current with each other in the drying chamber 54.

Since a number of inlet orifices 12a are placed one over the other the drying gas can penetrate to the biomass at the location of the core within the peripheral wall. The 30 drying gas that is introduced through the top inlet orifice 12a forms a stream of hot gas along the inside of the peripheral wall 50. Owing to this flow, the drying gas that has been introduced through the inlet orifice 12a below the first one is forced to move away from the peripheral wall 50 and is directed radically inward. This is indicated 24 schematically by the arrows D. This ensures that not only the biomass by the peripheral wall but also the biomass in the middle is able to dry fully.

Steam is generated during the drying of the biomass in the drying chamber 54. Part of this steam and the drying gas cooled by evaporation leaves the torrefaction 5 reactor 10 through outlet orifices 15, located sideways in the peripheral wall 50. The steam produced is preferably largely passed into the torrefying chamber 55 of the torrefaction reactor 10, because the steam generally contains a considerable amount of organic compounds.

When the biomass surpasses the level indicated by the dashed line C, the biomass 10 is almost fully dry, i.e. the residual moisture has almost completely evaporated from the biomass. The moisture content of the biomass is then preferably < 3%. The temperature of the biomass has risen to about 200 °C at the same time. Therefore, what happens above the level shown by the dashed line C is torrefaction. The biomass is then located in the torrefying chamber 55 for torrefying the biomass.

15 The torrefying chamber 55 has inlet orifices 12b for torrefying gas, which are located in the top section 52 of the torrefaction reactor 10. The torrefying gas is the hot gas introduced into the torrefying chamber to torrefy the biomass. The torrefying gas flows from the inlet orifices 12b downwards through the biomass. The torrefying gas moves in counter-current to the biomass. In the second reaction space 55, the biomass 20 is torrefied as it moves upward. As the biomass is heated to the maximum torrefying temperature Tt0rr, combustible torrefaction gases are formed in the second reaction space 55. The amount of combustible torrefaction gas increases by maintaining this temperature for some time. The torrefying gas introduced and the torrefaction gases formed leave the second reaction space 55 through outlet orifices 14. The inlet orifices 25 12b and the outlet orifices 14 may be used as torrefying chamber gas inlet 321 and torrefying chamber gas outlet 322, respectively.

The gas mixture leaving the torrefaction reactor 10 through the outlet orifices 14 will therefore contain relatively little steam according to the invention. Furthermore, the discharged combustible torrefaction gas will be hardly diluted with steam from the 30 drying chamber 54, if at all.

The torrefaction reactor 10 may have an overflow part 58. As the torrefied biomass is pushed over the edge of the overflow part 58, it overbalances along the overflow part 58 and falls into the cooling unit 40. The cooling unit has an inlet orifice 25 41 for the introduction of cooling gas. The temperature of the torrefied biomass decreases to room temperature in the cooling chamber 40. The cooled biomass leaves the cooling unit 40 through the outlet 42.

The biomass and the drying gas move in the drying chamber 54 in co-current 5 with each other. As a result, the residual moisture can be eliminated from the biomass quickly and efficiently. In the torrefying chamber 55, the biomass and the torrefying gas introduced move in counter-current to each other. This makes it possible to control the maximum torrefying temperature accurately.

Figure 4 schematically depicts another embodiment of the torrefying device 10 of 10 the invention.

In a variant, which may also apply to the above described embodiments, the drying chamber 54 is separate from the torrefying chamber 55. Optionally, they may be arranged in one single reactor, see also above. Further, there is a gas loop 541 depicted, which provides drying gas circulation in the drying chamber. This gas loop 541 may be 15 configured to provide a co-current or counter current drying gas gas flow direction within the drying chamber 54. The gas loop may comprise a second gas transport device 542 (such as a pump, a blower, a fan, a compressor, etc.). Further, the gas loop 541 may comprise a heater 543. Optionally, the gas loop may further comprise a drain (not depicted, to remove water from the gas loop 541). The gas loop 541 especially 20 transports steam. Alternatively, such drain may not be present, and surplus steam may be removed via the torrefying chamber 54 (especially via outlet 322).

Further, this schematically depicted embodiment includes an alternative arrangement of the gas transport structure 330. Here, gas 321 is extracted from the torrefying chamber 55 and gas 311 is introduced in the torrefying chamber, at those 25 sides of the torrefying chamber 55 where the organic material is introduced in the torrefying chamber and torrefied material is extracted from the torrefying chamber 55. In this way, no openings in the wall 50, especially in the part of the wall 50 along which organic material is transported, may be necessary. Again, the gas transport structure 330 may be arranged to facilitate co-current or counter-current (as depicted 30 here) gas flow within the torrefying chamber 55.

Here, by way of example, the gas transport structure 330 comprises an additional heater 358, downstream of the gas transport device 370. In a variant, part of the gas of within the gas transport structure 330, especially downstream of the heating chamber 26 350, may be removed from the gas transport structure 330 and may for instance be fed to another device 390, such as an after burner. Heat thereof may again be used to heat parts of the device 10 of the invention. The gas 311 introduced again in the torrefying reactor 55 preferably has a temperature of at least 200 °C, especially at least 220 °C.

5 Figures 1 and 4 show gas loops. As indicated above, in further embodiments, the torrefying device 1 does not have such gas loop, and gas after cooling in the cooling chamber 340, or optionally after the optional heater or optionally after the optional gas transport device, the remaining gas may be fed to another device, such as an after burner. Heat thereof may be used to heat the torrefying chamber 55 and/or the optional 10 drying chamber 54 and/or gas fed into the torrefying reactor 55.

As indicated above, parts of the device may be operated at pressurized conditions, such as by way of example up to 5 bar. This may require additional elements, which are for the sake of understanding not depicted in the present drawings.

Claims (19)

A torfaction device comprising: a. A torrefaction chamber (55) configured to torreficate a stream of organic material, the torrefaction chamber further comprising a torrefaction chamber gas inlet (321) for supplying a gas and a torrefaction chamber gas outlet ( 322) for removing torrefaction chamber gas from the torrefaction chamber; b. a gas transport structure (330) connecting the torrefaction chamber gas outlet (322) to the torrefaction chamber gas inlet (321), the gas transport structure further downstream of the torrefaction chamber gas exit and upstream of the torrefaction chamber gas inlet a cooling chamber (340 with a cooling chamber opening (341) therein for discharging of condensed liquid material, and downstream of the cooling chamber and upstream of the torrefaction chamber gas entrance comprises a heating chamber (350) c a gas propulsion apparatus (370) configured to return torrefaction chamber gas from the torrefaction chamber gas outlet (321) through the gas transport structure (330) to transport to the torrefaction chamber gas inlet, d) a feeder (53) configured to transport organic material through the torrefaction chamber, the feeder, the gas inlet and the gas outlet being configured such that the gas in the torrefaction chamber is countercurrent to the torrif icing organic material. The torfaction device of claim 1, wherein the cooling chamber (340) comprises a heat exchanger (345) configured to facilitate cooling of the torrefaction chamber gas. 3. Torrefaction device according to claim 2, wherein the heat exchanger (345) is further configured to facilitate transport of liquid material to the cooling chamber opening (341). The Torrefaction apparatus of claim 3, comprising substantially vertical cooling elements (346) that promote a smooth flow of condensed liquid material into the cooling chamber (340). The Torrefaction device according to any of the preceding claims, wherein the cooling chamber (340) is configured to facilitate transport of liquid material to the cooling chamber opening (341). 6. Torrefaction device as claimed in any of the foregoing claims, wherein the heating chamber (30) comprises a heating chamber opening (351) for discharging liquid material. Torrefaction device according to any of the preceding claims, wherein the heating chamber (350) comprises a heat exchanger (355) configured to facilitate heating of the torrefaction chamber gas. The Torrefaction apparatus according to claim 7, comprising substantially vertical heating elements (356) that promote a smooth flow of condensed liquid material into the heating chamber (350). 20 The Torrefaction device of any one of the preceding claims, wherein the heating chamber (350) is configured to facilitate transport of fluid material to a heating chamber opening (351). The Torrefaction device according to any of the preceding claims, further comprising a receiver (360) adapted to collect liquid from the cooling chamber (340) and optionally from the heating chamber (350). 11. Torrefaction device according to claim 10, further comprising a temperature controller (380) configured to control the temperature of the receiver. A method for the thermal treatment of organic material comprising: a. Torrifying, in the absence of an external oxygen source and at a temperature of 200-350 ° C, an organic material in a torrefaction chamber of a torrefaction apparatus; 5 b. removing torrefaction chamber gas from the torrefaction chamber, subjecting the removed torrefaction chamber gas to a treatment, and after treatment reintroducing the treated torrefaction chamber gas into the torrefaction chamber, the treatment comprising cooling in a cooling chamber and subsequent heating; C. collecting liquid material formed in the cooling chamber in a receiver; d. maintaining a counterflow of the torrefaction chamber gas with respect to a flow of the organic material through the torrefaction chamber. The method of claim 12, wherein the cooling comprises cooling to a cooling temperature selected from the range greater than the dew point of water and smaller than the maximum torrefaction temperature in the torrefaction chamber. 14. A method according to claim 13, wherein cooling is carried out to a cooling temperature of 110-180 ° C. The method of any one of claims 12-14, further comprising receiving fluid material from the heating chamber in the receiver. The method of claim 15, further comprising storing the receiver at a temperature of at least 30 ° C and below the condensation temperature of water. The method of any one of claims 12-16, wherein the torrefaction device 30 of any one of claims 1-13 is used. The method of any one of claims 12-17, wherein the torrefication takes place at a temperature of 220-320 ° C. A condensate obtainable after treatment with the method according to any of claims 12-18.