Method and apparatus for extracting a product from a heat treatment process

Abstract

The present invention relates to a method for treating vent gases from the thermal treatment of plant biomass.The present invention also relates to an apparatus for carrying out a method for treating vent gases from the thermal treatment of plant biomass. [Selected Figure] Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating vent gas vapors from the thermal treatment of plant biomass. The present invention also relates to an arrangement for carrying out this method. [Background technology]

[0002] Heat treatment of plant biomass causes permanent changes in the biomass' physical and chemical properties. Materials are released and removed from the biomass, such as covalently bonded water, which is removed as steam. Heat treatment also forms and releases small oxygen-containing organic molecules from the biomass, such as methanol and acetic acid, and releases natural chemical compounds and substances from the treated biomass. Heat-treated biomass, such as wood, resists changes in humidity and temperature, making it suitable for a variety of purposes.

[0003] Material released from the biomass during thermal treatment is partially in gaseous (gas or aerosol) form, typically removed as vent gas for processing, and part of the released material is in liquid form, flows down the bottom of the thermal treatment chamber, and typically exits the chamber for processing.

[0004] Heat treatment involves the exhaustion of sufficient oxygen by a shielding gas to prevent combustion or partial oxidation of the treated material by oxygen. The shielding gas may be steam, i.e., gaseous water. When the solid material to be treated is introduced into the process, as well as water in the form of heat and steam or liquid water for cooling, the water for cooling quickly evaporates to form steam at the temperatures used in the heat treatment process.

[0005] The thermal treatment forms an exhaust stream of vent gas streams containing materials released from the biomass. One drawback associated with conventional arrangements is that the materials released from the biomass and contained in the vent gas streams are processed to prevent the valuable components contained therein from being used. A further drawback is that some of the components of the disposed material may have adverse environmental effects. Summary of the Invention

[0006] It is an object of the present invention to provide a method for handling vent gas vapors from the thermal treatment of plant biomass, and an arrangement for carrying out said method, which overcomes the above-mentioned drawbacks.

[0007] The object of the invention is achieved by a method and an arrangement which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are set out in the dependent claims.

[0008] The present invention is based on the realization that by using a series of condensers, each operated at a different temperature with the temperature in the condenser being lower than in the previous condenser, the material contained in the vent gas stream is selectively separated into smaller amounts.

[0009] In one embodiment, a method for treating vent gas steam from the thermal treatment of plant biomass includes: heat treating the plant biomass in a heat treatment chamber; directing vent gas streams from the heat treatment to a series of interconnected condensers and providing a flow of the vent gas streams through the series of condensers; collecting at least a portion of the components of the vent gas vapor in each condenser; each condenser being set to a temperature lower than the temperature in the previous condenser in the series; The first condenser in the series is set to a temperature lower than the temperature in the thermal treatment chamber.

[0010] An advantage of the present invention is that products can be selectively separated from the vent gas stream to provide a variety of refined valuable products that can be used directly or further processed to produce usable products.

[0011] A further advantage of the present invention is that materials released from the biomass are recovered in a controlled manner without being released into the environment. [Brief explanation of the drawings]

[0012] The invention will now be described in more detail by way of preferred embodiments with reference to the accompanying drawings in which:

[0013] [Figure 1] 1 shows a schematic diagram of an example of an apparatus for the thermal treatment of plant biomass. [Figure 2] A schematic diagram of an example of a condensation system including a series of condensers for handling vent gas vapor is shown. The vapor volumes of condensers L1 to L4 are shown at normal temperature and pressure (NTP). DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention is based on a method for treating vent gas steam from the thermal treatment of plant biomass.

[0015] The heat treatment product from the heat treatment chamber is an exhaust stream of vent gas streams, which are gaseous materials (gases, aerosols) that include materials released from the biomass.

[0016] It has surprisingly been found that vent gas streams can be processed to produce solid or liquid products (at room temperature) by dividing the vent gas streams in a condenser. The vent gas streams are directed from the thermal treatment chamber to a condensation apparatus that includes a series of multiple condensers, preferably three or more condensers, set at different temperatures. In the series, the temperature of one condenser is higher than the temperature of the next. In this way, specific products are collected from the vent gas streams at specific treatment times and condensation temperatures.

[0017] In one embodiment, a method for treating vent gas vapors comprises the steps of: heat treating the plant biomass in a heat treatment chamber; directing the vent gas stream from the heat treatment chamber to a series of interconnected condensers and supplying the vent gas stream through the entire series; collecting at least a portion of the components of the vent gas vapor in each condenser; Each of the condensers is set to a lower temperature than the temperature in the previous condenser in the series.

[0018] In one embodiment, the series of condensers includes three or more condensers. In another embodiment, the series of condensers includes three to six condensers. In another embodiment, the series of condensers includes four condensers. In another embodiment, the series of condensers includes five condensers. In another embodiment, the series of condensers includes six condensers.

[0019] When biomass is heat treated between approximately 160°C and below the point at which carbonization begins, defined as the onset of exothermal degradation of cellulose, the biomass undergoes permanent changes in its composition and structural qualities. The temperature at which a material begins to decompose exothermically varies depending on the material in question, and generally ranges between 260°C and 300°C for different types of plant biomass.

[0020] In one embodiment, the heat treatment of the plant biomass is carried out at a temperature of from 160°C to 300°C.

[0021] In another embodiment, the plant biomass is wood.

[0022] Prior to heat treatment, the biomass may be dried at temperatures up to 150° C. as part of the process to achieve a fixed moisture content. In one embodiment, the biomass may be dried at temperatures from 100° C. to 150° C.

[0023] The vent gas stream may also include steam used in the process as a shielding gas if steam is used as a shielding gas to prevent combustion or partial oxidation of the treated biomass by oxygen. The steam may be introduced for heat treatment, may be derived from a separation system or device that provides heat to water to create steam, or may be created in situ in the heat treatment chamber by adding liquid water to vaporize the steam.

[0024] In one embodiment, steam is used as a shielding gas during heat treatment.

[0025] The thermal treatment process induces physical and chemical changes in the treated biomass, including, but not limited to, the release of covalently bound water and the formation of small oxygen-containing organic molecules such as acetic acid and methanol. The effects of thermal treatment also include the removal of transformed and formed materials released from the treated biomass. In addition, some materials naturally occurring in unmodified form or as products of the thermal treatment process are removed from the treated biomass through the principle of steam distillation. The principle of steam distillation is the effect of the boiling and condensation temperatures of a mixture of two or more immiscible phases when forming the majority of one of the immiscible phases in a complex, continuous series of mixtures released from the biomass during thermal treatment. Steam distillation requires that steam, or gaseous water, be maintained at a temperature greater than 100°C during thermal treatment.

[0026] In a heat treatment process, a long temperature program lasting several tens of hours causes a series of physical and chemical changes that result in the release of successive materials into the gas phase at different times. For compounds with high boiling points, the release may occur at temperatures well below the boiling point of the compound.

[0027] Compounds contained in materials released from biomass into the gas phase and carried in the vent gas stream may thus be separated over a specific process time frame, and the compounds may then be collected as classified, essentially purified products produced by successive condensations in a condensation system comprising a series of condensers operated at specific temperatures.

[0028] It has surprisingly been discovered that in a series of condensations in which compounds released in the same or overlapping time frames based on their respective boiling points are collected in a series of condensers, if the temperature in a previous condenser is higher than in the next condenser, the compounds condensed in the previous condenser will not be carried in sufficient quantities to the next condenser.

[0029] In the process of the present invention, successive condensations produce products with no or trace amounts of impurities, allowing for the use or production of the product without the need for additional procedures such as drainage or distillation. Each condensate in the successive condensations consists of one, two, or many immiscible phases that are optionally separated by decantation.

[0030] In the method of the present invention, conditions are applied according to the qualities, such as the origin, composition, and texture, of the plant biomass in question. For example, the temperature at which the material begins to exothermically carbonize varies with the plant biomass in question and is generally between 260°C and 300°C for different types of plant biomass. The temperature selected for the heat treatment affects the composition of the material released from the biomass, i.e., the selection and amount of substances and compounds in the released material. Also, characteristics such as the plant species, the part of the plant treated, particle size, and moisture content of the biomass, as well as the type and amount of compounds released from the biomass, influence the selection of process conditions through variations in the release time frame and temperature.

[0031] The method of the present invention includes control of the heat treatment equipment and condensation equipment, including, but not limited to, the heating rate during the heat treatment process, the rate of steam introduced into the process, and the temperature of the condenser, all of which process parameters are controlled at predetermined times or processing windows.

[0032] The pressure in the thermal treatment chamber is limited by preventing condensation due to pressure drop at the chamber outlet. In condenser systems, the pressure is typically several tens of millibars above ambient. There is also likely to be a contribution to the back pressure of the condenser system.

[0033] The flow rate (kg / h) during the process varies depending on the size of the treatment chamber, the process parameters, and the stage of the process. The flow rate also depends on the velocity of the shielding gas vapor introduced into the heat treatment chamber. When the first condenser in the series is reached, set at a temperature below 100°C, the flow rate is reduced by more than 90%. The reduced flow rate acts as an exhaust if backflow is prevented or a vacuum pump is placed after the first condenser in the series set at a temperature below 100°C.

[0034] In one embodiment, the first condenser in the series is set to a temperature above 100°C and the next condenser is set to a temperature below 100°C.

[0035] In another embodiment, the first condenser in the series is set to a temperature of at least 100°C, and the next condenser is set to a temperature below 100°C.

[0036] In another embodiment, the series of condensers includes at least two condensers set at a temperature above 100°C and at least one condenser set at a temperature below 100°C.

[0037] In another embodiment, the series of condensers includes at least two condensers set to a temperature of at least 100°C and at least one condenser set to a temperature below 100°C.

[0038] During the heat treatment process, three main types of condensates, or phases, are formed. Phase 1, the so-called wood vinegar phase, is a liquid phase containing many other compounds in varying concentrations. Phase 1 is a substance such as wood vinegar (EC 232-450-0, CAS 8030-97-5). Phase 2, the terpene phase, is a water-immiscible, yellowish liquid phase containing alpha-pinene and other isoprene polymers. Phase 3, the tar phase, is a dark-colored phase that is water-immiscible and often insoluble in the wood vinegar or terpene phases. All phases 1 through 3 are formed during the entire heat treatment, but their compositions and relative proportions vary.

[0039] The first condenser, set at a temperature above 100° C., condenses phases 1 and 3. The next condenser, set at a temperature below 100° C., condenses phases 1 and 2.

[0040] In another embodiment, the series of condensers includes a condenser set at a temperature greater than 130°C, a condenser set at a temperature greater than 100°C to 120°C, and a condenser set at a temperature less than 100°C.

[0041] In yet another embodiment, the series of condensers includes a condenser set at a temperature of 120°C to 160°C, preferably 120°C to 140°C, more preferably 130°C, a condenser set at a temperature of greater than 100°C to 120°C, preferably 105°C to 115°C, more preferably 105°C, a condenser set at a temperature of 80°C to less than 100°C, preferably 80°C to 95°C, more preferably 90°C, and a condenser set at a temperature of 20°C to 60°C, preferably 20°C to 40°C, more preferably 30°C.

[0042] In yet another embodiment, the series of condensers includes a condenser set at a temperature of 120°C to 140°C, a condenser set at a temperature of 105°C to 115°C, a condenser set at a temperature lower than 80°C to 100°C, and a condenser set at a temperature of 20°C to 60°C.

[0043] In yet another embodiment, the series of condensers includes a condenser set at a temperature of 130°C, a condenser set at a temperature of 105°C, a condenser set at a temperature of 90°C, and a condenser set at a temperature of 30°C.

[0044] In another embodiment, when the heat treatment temperature is higher than 180°C, materials contained in the vent gas stream are removed, where sufficient amounts of various substances and compounds are released from the plant biomass.

[0045] When the heat treatment temperature is between 180 and 200°C, the first condenser set at a temperature above 100°C condenses the tar phase, which contains substances such as water-insoluble high-purity tall oil (EC 232-304-6, CAS 8002-26-4), which is part of phase 3, and contains limited amounts of various fatty and resin acids. At heating temperatures above 200°C, the minor fraction, such as tall oil, also contains plant sterol compounds.

[0046] The next condenser in the series, set at a temperature above 100°C, produces a material such as wood vinegar (EC 232-450-0, CAS 8030-97-5). The next condenser in the series, with the first condenser set at a temperature below 100°C, produces wood vinegar and a terpene phase, turpentine, along with small amounts of water-methanol mixtures, methyl acetate, and similar low-boiling, water-immiscible esters and ethers.

[0047] The present invention is also based on an arrangement for treating vent gas steam from the thermal treatment of plant biomass. The arrangement includes a thermal treatment chamber for thermally treating plant biomass to produce vent gas steam, a series of condensers, an exhaust tube directing the vent gas steam from the thermal treatment chamber to the first condenser, and pipes connecting the condensers in the series. During the thermal treatment of the plant biomass, the apparatus is configured to set the temperature of each condenser in the series to be lower than the temperature in the previous condenser in the series, and the temperature of the first condenser in the series is set to be lower than the temperature in the thermal treatment chamber. The apparatus may also include a system and conduits for supplying steam to the thermal treatment chamber.

[0048] The exemplary arrangement shown in Figure 1 includes a heat treatment chamber 1 in which biomass is placed for heat treatment, and an exhaust tube 2 for removing water from the heat treatment chamber. Optionally, the arrangement includes a system and a conduit 3 for supplying steam to the heat treatment chamber. The arrangement also includes a pipe 4 for hot oil and a hot oil boiler 5 for supplying heat to the heat treatment chamber, a blowing unit 6 for circulating gas in the heat treatment chamber, and an exhaust tube 7 for venting gas steam.

[0049] The exemplary arrangement further includes a condensation device including a series of condensers connected to each other by pipes to remove at least a portion of the materials contained in the vent gas stream. The exemplary condensation device shown in FIG. 2 includes a series (in series) of four condensers L1, L2, L3, and L4. The first condenser in the series, L1, is connected to the exhaust tube 7 of the heat treatment chamber and directs the vent gas stream through the series of condensers. All condensers in the series are connected to each other by pipes. Condenser L1 has a higher temperature than condenser L2, which has a higher temperature than condenser L3, which has a higher temperature than condenser L4. In this manner, each condenser collects substantially different compounds and substances from the vent gas stream due to the gradual decrease in temperature as the vent gas stream passes through the series of condensers.

[0050] In one embodiment, the series of condensers includes three or more condensers. In another embodiment, the series of condensers includes three to six condensers. In another embodiment, the series of condensers includes four condensers. In another embodiment, the series of condensers includes five condensers. In another embodiment, the series of condensers includes six condensers.

[0051] In another embodiment, the major materials contained in the vent gas stream are removed in a condenser.

[0052] When using the arrangement according to Figure 1, plant biomass 8 is placed in the heat treatment chamber 1 for heat treatment.

[0053] The condensers are operated at a higher temperature than the next condenser in the series. In the exemplary arrangement shown in Figure 2, condenser L1 removes larger compounds, such as large organic compounds and other high-boiling organic compounds, that condense before acetic acid as a tar phase. Condenser L1 is designed to allow 750 kg / h of steam (500 kg / h of which is directed to thermal treatment) to flow through without much back pressure. Condenser L2 condenses organic compounds with a boiling point higher than water as a pyroligneous acid phase and as a terpene phase, leaving water in the gas phase. Condenser L2 is designed to allow 700 kg / h of steam (500 kg / h of which is directed to thermal treatment) to flow through without much back pressure. Condenser L3 condenses water as a diluted pyroligneous acid phase, a terpene phase, and other compounds in low concentrations, leaving 800 kg / h. 3 150m from the / h level 3 / h. Condenser L4 condenses the terpene phase and liquid phase compounds such as volatile organic compounds, terpenes, methanol, methyl acetate (some of which are immiscible with water), and water depending on the dew point. Condenser L4 condenses the vent gas vapor at the dew point level and the flow is reduced to 100 m 3 / h The condensate collected from the condenser may optionally be filtered, distilled, or otherwise purified to remove desired materials or compounds.

[0054] In another embodiment, the arrangement of the present invention is configured to perform the method of the present invention.

[0055] example Example 1. Simplified system with sampling method Heat treatments were performed on sawn lumber samples of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). The samples had two different ferent physical dimensions: thick and thin. The heat treatments for each of the four types of samples were performed identically. Thus, a total of eight heat treatments were performed.

[0056] The heat treatment was carried out using steam as a shielding gas and in accordance with the Thermo-D class product process, which involves an initial rapid temperature increase to approximately 100°C, then a slower increase to 130°C to remove much of the moisture from the wood, a heat treatment step in which the temperature is initially increased slowly to 200°C, followed by a hold above 200°C, and a cooling step in which the temperature is reduced with a water spray.

[0057] Sampling was carried out in a condenser system consisting of two condensers connected in series, the first condenser L1 at 110°C and the second condenser L2 at 30°C. Each of the eight processes was sampled i) during the temperature increase from 180°C to 200°C, and ii) while the temperature was held above 200°C until the end of the holding phase, before the start of the cooling phase. Samples were collected from both condensers L1 and L2 during each phase i) and ii).

[0058] Sample collection was performed from the exhaust tube of the vent gas vapor. A small portion of the vent gas vapor was directed through a branch pipe to the condenser via the expansion tank, and the exhaust gas from the condenser L was further directed to the outside air. The majority of the vent gas vapor was sucked into the transport blower. In the first three collections, the branch pipe was directed as far outside as possible, facing downwards, and the expansion tank and condenser were attached to the outer wall of the heat treatment chamber above the outside, with the bottom of the expansion tank uninsulated. In the remaining five collections, the branch pipe, expansion tank, and condenser were located on the inside of the outer wall of the heat treatment chamber, between the chamber and the outer wall. In this case, the entire expansion tank was also insulated, and the entire arrangement was thereby protected from the cooling effects of weather and wind.

[0059] In addition to the samples collected from condensers L1 (110°C) and L2 (30°C), a compilation sample was collected from the bottom of the expansion tank, where a sufficient amount of water was collected. The surface temperature of the exhaust tube before the shut-off valve, approximately 20 cm from the main tube insulation, varied between 110°C and 170°C, depending on the process phase and the branch pipe flow. However, the temperature of the vent gas vapor entering condenser L1 was generally between 90°C and 98°C. This means that compounds with boiling points higher than this temperature were mainly collected in the compilation sample.

[0060] Sample collection consisted of samples i) and ii) from both condensers L1 and L2, as well as an edited sample from the expansion tank. Thus, a total of five samples were obtained from each of the eight heat treatments, each generally containing at least two phases. The total sample volume from all experiments was thus 80, consisting of samples of 10 different phases from each of the eight different heat treatments.

[0061] Using the sampling system described above, three distinct phases were separated from the samples: an oily terpene phase (2) containing terpenes and lighter than water; a water-containing wood vinegar phase (1) with significant concentrations of other compounds; and a black, variable-flow, complex-composition tar phase (3). Phases 1–3 were present in the edited samples and in samples collected from condenser L1, while phases 1 and 2 were present in samples collected from condenser L2.

[0062] Collection times were generally shorter for thin wood than for thick wood, and longer for spruce than for pine.

[0063] The collection was successful, with sample material collected from the vent gas vapors of the heat-treated wood manufacturing process. The largest volume fraction was the wood vinegar phase, an aqueous fraction containing various water-insoluble compounds at concentrations of many percent of the total volume. The aqueous fraction has commercial value, either on its own or as a more refined product. The terpene phase, an oily fraction from pine used as such, is also important. The tar fraction contains commercially usable compounds, and the tar itself is a useful product.

[0064] The collected samples contained 91 to 97% water by volume, or water-soluble compounds such as acetic acid, formic acid, methanol, and furfural. The oily fraction, or terpene phase, accounted for less than 1% of the vent gas vapor from the spruce sample and approximately 5% of the vent gas vapor from the pine sample. Terpenes accounted for approximately 10% of the condensate from condenser L2. The tar phase accounted for an average of 2 to 4% of the total collected aqueous phase volume. Acetic acid accounted for an average of 3.3% of the total aqueous phase volume and approximately 3.1% of the total volume of the collected liquid material. Furfural accounted for an average of 0.7% of the total aqueous phase volume and approximately 0.6% of the total material. The terpene phase accounted for approximately 4% of the total volume of the collected liquid material.

[0065] In addition to water, compounds obtained from the aqueous phase are primarily compounds such as acetic acid, methanol, and furfural. The terpene phase may be used as both a chemical agent or an energy source. When the wood temperature exceeds 170°C during the process, the terpene phase accounts for 10% by volume of the liquid volume that condenses below 100°C. Other compounds may also be extracted and used, as their number may be in the hundreds or thousands.

[0066] Example 2. Complex collection system with sampling methods Heat treatment was performed on sawn lumber samples of Scots pine (Pinus sylvestris). The samples were of thick physical dimensions, and the heat treatment was performed twice on the same sample using different sampling systems. Heat treatment was performed as in Example 1.

[0067] The first process was collected from 110°C to the end of the holding phase and during the cooling phase to 112°C. Sample collection vessels were changed at the critical temperature of 170°C, the end of the holding phase, and the end of the cooling phase. Sample collection vessels were also changed during the process whenever full capacity was reached.

[0068] The second process was collected from 170°C to the end of the holding phase, i.e., before the cooling phase began. The sample collection vessel was changed during the process whenever it reached full capacity.

[0069] Sampling was performed in a condenser system consisting of six condensers (L1-L6) connected in series. The first condenser (L1) was at 140°C, the second condenser (L2) at 120°C, the third condenser (L3) at 105°C, the fourth condenser (L4) at 90°C, the fifth condenser (L5) at 60°C, and the sixth condenser (L6) at 10°C. Samples were collected separately from each condenser, and each sample from each condenser contained two phases. The total volume of samples collected during the first process was approximately 38 liters, and during the second process approximately 25 liters.

[0070] Sample collection was performed from the vent gas vapor exhaust tube, where a small amount of vent gas vapor was directed through a heated branch pipe and an expansion tank to the condenser, and the exhaust gas from the condenser was further directed to the outside air. During sampling from the first process, the transport blower was closed, and the gas vapor was discharged to the outside air. During sampling from the second process, the majority of the vent gas vapor was drawn into the transport blower. Between the first and second treatment processes, a pressure difference of several tens of pascals occurred between the outlets of the main pipe and the branch pipe. This pressure difference was due to the use of the transport blower in the second treatment process. The pressure difference was the main cause of the difference in the total sample volume collected from the two processes.

[0071] The temperature of the external surface of the vent gas steam exhaust tube under the insulation in front of the shut-off valve varies between 110 and 170°C depending on the process stage. The temperature of the vent gas steam stabilizes at about 120 to 150°C in the branch pipe before entering the condenser.

[0072] At heat treatment temperatures between 180 and 200°C, the condensate from condenser L1 was a highly pure tallow oil-like material (as determined by light color and IR spectra). At heat treatment temperatures above 200°C, there were small amounts of plant sterol-like compounds contained in the tallow oil.

[0073] The volume of liquid collected from each of condensers L1, L2, and L3 was approximately 5% to 10% by weight of the total volume of collected liquid. Samples from condensers L2 and L3 contained a small portion of oily terpines and a water-containing wood vinegar phase. Samples from condensers L1 through L3 contained a small amount of water due to the cold spots of the condensers.

[0074] The majority of the total condensed volume was collected in condensers L4 and L5. The volume of liquid collected from L4 accounted for approximately 50% of the total volume collected. The largest fraction of the condensate in L4 and L5, respectively, was an aqueous wood vinegar phase containing decomposed acids, alcohols, furfural, and other small oxygen-containing compounds. A substantial second phase of terpenes was also present. At temperatures above 180°C, when the steam / water introduced into the heat treatment peaked, the capacity of L4 was exceeded, and a portion of the aqueous phase was condensed in L5.

[0075] Condenser L6 has only a trace amount of condensate, in some cases none.

[0076] Based on the results of Examples 1 and 2, it can be concluded that two condensation systems would not achieve sufficient separation, while six condensation systems would have some excess and unnecessary capacity. The process parameters, the quality of the plant biomass being processed, and the type of product desired will affect the number of condensers required to achieve the desired results. The number of condensers may exceed six.

[0077] Ready-made solutions that may be applied to further treat the aqueous condensate of the present invention are commercially available for separating small amounts of oxygen-containing molecules from aqueous materials.

[0078] The purified water may be reused according to circular economy principles by distilling it into steam for use in processes, using purification from compounds with a higher boiling point than water and / or filtration, e.g., reverse osmosis, so that the more concentrated solution contains usable substances or compounds.

[0079] It is obvious to a person skilled in the art that with the advancement of technology, the concept of the present invention can be implemented in many ways. The present invention and its embodiments are not limited to the examples described above, but can vary within the scope of the claims.

Claims

1. 1. A method for treating vent gas steam from the thermal treatment of plant biomass, the method comprising: heat-treating the plant biomass in a heat treatment chamber at a temperature between 160°C and below the carbonization temperature, defined as the temperature before the onset of exothermic decomposition of cellulose, at a pressure of several tens of millibars above atmospheric pressure; directing the vent gas stream from the heat treatment through a series of interconnected condensers to form a flow of the vent gas stream through the entire series of condensers; collecting at least a portion of the vent gas vapor composition in each condenser; The series of condensers is such that each successive condenser is set to a temperature lower than the temperature of the previous condenser in the series; the series of condensers includes three or more condensers, including a condenser set at a temperature greater than 130°C, a condenser set at a temperature between 100°C and 120°C, and a condenser set at a temperature less than 100°C; a first condenser in the series of condensers is set at a temperature lower than the temperature in the heat treatment chamber; A method in which plant biomass is not carbonized during the heat treatment.

2. The method according to claim 1, wherein steam is used as a shielding gas during heat treatment.

3. 3. The method of claim 1 or 2, wherein the plant biomass is wood.

4. The method according to any one of claims 1 to 3, wherein the plant biomass is dried before the heat treatment.

5. 1. An apparatus for treating vent gas steam from the thermal treatment of plant biomass, comprising: The apparatus includes a heat treatment chamber for heat treating plant biomass to produce a vent gas vapor, a series of condensers, an exhaust tube directing the vent gas vapor from the heat treatment chamber to a first condenser, and pipes connecting the condensers to each other in the series of condensers; During the thermal treatment of plant biomass, the temperature in each successive condenser in the series is set lower than the temperature in the previous condenser in the series; the temperature of the first condenser in the series of condensers is set lower than the temperature in the heat treatment chamber; the series of condensers includes three or more condensers, including a condenser set at a temperature greater than 130°C, a condenser set at a temperature between 100°C and 120°C, and a condenser set at a temperature less than 100°C; An apparatus designed for non-carbonizing thermal treatment of plant biomass at temperatures from 160°C to below the carbonization temperature, defined as before the onset of exothermic decomposition of cellulose, at pressures several tens of millibars above atmospheric.

6. 6. The apparatus of claim 5, further comprising a system and conduits for supplying steam to the thermal treatment chamber.

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