Method for controlled production of biooil

Abstract

The present relates to a method for controlled production of biooil by thermal liquefaction of a lignocellulosic biomass, the method comprising the steps of - Providing the lignocellulosic biomass - Mixing the lignocellulosic biomass with an oil solvent, preferably a biooil, to obtain a primary slurry - Reacting the primary slurry in a first reaction stage at t1, res1 obtaining a first reaction product - Reacting at least part of the first reaction product in a second stage t2, res2 obtaining a second reaction product and - Adding an alcohol reactant to the primary slurry before and / or during the first stage and / or to the first reaction product before and / or during the second stage.

Description

[0001] Method for controlled production of biooil

[0002] Field of the invention

[0003] The present invention relates to production of biooils from biomass preferably a lignocellulosic biomass in a process based on recirculated product biooil as liquefaction solvent.

[0004] Background

[0005] Solvent liquefaction is a thermochemical method widely known in the art for producing biocrude oil from lignocellulosic biomass. While the composition and stability of bio-oils varies widely between different feedstocks and methods of production, these can typically be directly used as a crude liquid fuel or, with some additional treatment, co-processed along with petroleum-crude to refined commercial transport fuels.

[0006] The term "hydrothermal liquefaction" (HTL) is applied to solvent liquefaction processes in which the solvent is water. These processes are typically applied to feedstocks which comprise a substantial water content. For comparatively dry biomass feedstocks, however, recirculated product oil or some fraction thereof can itself be advantageously used as solvent. Further addition of ethanol and / or methanol in these processes produces synergistic effects whereby the inherent advantages of using recirculated product oil as solvent are amplified and an overall reduction is obtained in undesirable product oil acidity. (WO2021 / 209555).

[0007] The produced biooil is complex and the reactions taking place during the thermal liquefaction are many and competing depending on parameters such as solvent, biomass, temperature, residence time, added reactants, catalysts etc. The process steps and conditions may lead to sub optimal yields and undesired components such as char, gas and heavy components as well as components which may increase acidity of the process if not properly optimized. Objects of the invention

[0008] It is an object of the present invention to provide a controlled method for producing biooil from biomass such as lignocellulosic biomass to provide an optimized biooil product.

[0009] Summary of the invention

[0010] This and other advantages are provided by a method for controlled production of biooil by thermal liquefaction of a biomass, such as lignocellulosic biomass, the method comprising the steps of

[0011] Providing the biomass

[0012] Mixing the biomass with an oil or oilbased solvent, preferably a biooil, to obtain a primary slurry

[0013] Reacting the primary slurry in a first reaction stage at temperature Tl, residence time resl obtaining a first reaction product

[0014] Reacting at least part of the first reaction product in a second stage at temperature T2, residence time res2 obtaining a second reaction product and

[0015] Adding an alcohol reactant to the primary slurry before and / or during the first stage and / or to the first reaction product before and / or during the second stage.

[0016] By carrying out the thermal liquefaction process in two or more reaction stages it is possible to control and optimize the reactions taking place during the liquefaction process. This may especially be the case if the process conditions comprising temperature (T) and residence time (Res) are not the same in at least two of the reaction stages.

[0017] It may be preferred if the alcohol reactant is a short chained primary alcohol, preferably ethanol and / or methanol.

[0018] In some embodiments the reaction in the first reaction stage takes place at a temperature Tl of 120 - 300C, such as 120 - 220C, such as 160 - 290C. In some embodiments Tl may even be as low as down to 80C such as down to 90, 100 or 120C. Especially the applicant has realized that the glass transition temperature of the lignin in the lignocellulosic biomass may play a critical role in enabling optimized solubility under the right conditions.

[0019] At the relatively low temperatures in the first reaction stage various reactions may take place including Esterification, transesterification, some depolymerization by cleavage of ether linkages in the presence of alcohol. At the low temperatures the lignocellulosic biomass may also be at least partially separated and lignin dissolved into the solvent oil.

[0020] The residence time Resl of the first reaction stage may be 10 - 30 min, such as 15 - 25 min. In some embodiments the residence time resl is above 10 min such as or above 20 min, 30 min, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 150, 180, 100, 220 or 240 min. In some embodiments the residence time resl is up to 20 min such as up to 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 150, 180, 100, 220 or 240 min or higher.

[0021] In some embodiments resl in the range 10 - 180min, such as 30 - 180 min may be advantageous for a T1 of 110 - 220C such as 120 - 220C, such as 100 - 150C with alcohol, oil and biomass present in the first stage.

[0022] A long resl may be particular advantageous if T1 is low. For example Resl may be above 90min at T1 below 150C.

[0023] In some embodiments the second reaction stage takes place at a temperature T2 of 250 - 450C such as 270 - 350C or 300 - 400C. For example, the temperature T2 in stage 2 may be 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440 or 450C.

[0024] If alcohol is added upstream or in the second reaction stage various reactions induced by the higher temperature may occur including depolymerization by cleavage of ether linkages and other bonds, deoxygenation by decarboxylation, deoxygenation by hydrogen donation from alcohol, inhibition of repolymerization

[0025] The residence time Res2 of the second reaction stage may be 1 - 20 min, such as 2- 15, such as 5 - 10 min, such as 2 - 40min. In some embodiments res 2 may be up to or between 20, 30 or 40 min even up to at least 50 min.

[0026] It may be preferred if alcohol is added to the primary slurry before and / or in the first reaction stage in order to help provide a lower viscosity of the primary slurry at lower temperatures. Alcohol may also reduce some of possible undesired reactions which at least to some degree may take place even at temperatures under 300C.

[0027] In some embodiments further alcohol may be added before and / or in the second reaction stage in order to ensure presence of sufficient alcohol in the second reaction stage.

[0028] In various other embodiments at least part of the alcohol is removed from the first reaction product before the second reaction stage in order to limit negative reactions with alcohol induced by higher temperatures. In case of no or limited alcohol in the second reaction stage the reaction temp may e.g. be 350 - 400 at a relatively short residence time such as below 20, or below 15min, such as below 10 min, such as 1 - 8 min, such as 3, 4, 5, 6, 7min.

[0029] The reaction temperature T2 with or without alcohol may also be lower such as 320C in some embodiments in which case the residence time t2 in some embodiments may be longer such as 10 - 40 min such as 20 min or 30 min.

[0030] Reactions in the second reaction stage at a T2 of 350 - 400C with no or limited alcohol may include Depolymerization, mild cracking, deoxygenation by decarboxylation.

[0031] In some embodiments the method comprises a step of reacting at least part of the second reaction product in a third stage T3 200 - 350C such as 250 - 350C, such as 300+- 25C res3 2 - 30 min or 2 - 15 min such as 5 - 10 minutes obtaining a third reaction product.

[0032] It may be advantageous to add alcohol and before and / or in the third reaction stage.

[0033] Especially in case of a second reaction stage with reduced or no alcohol present it may be advantageous to add alcohol before or to the third stage in order to supply alcohol to achieve a number of desired reactions to provide a third product oil with improved TAN and oxygen content. Reactions at moderately high T3 with alcohol may include Depolymerization by cleavage of ether linkages and other oxygen containing bonds, deoxygenation by decarboxylation, deoxygenation by hydrogen donation from alcohol, esterification reactions. In some embodiments it may be advantageous to remove water from the second reaction product before the third reaction stage.

[0034] In various embodiments T1 < T2 and / or T3 < T2 this may e.g. be achieved by a T1 of 195 +- 15C a T2 of 370+-30C and T3 of 300+- 25C. In some embodiments resl > res2 and / or res2 >res3 or res2 <res3. Applicant has shown that a process wherein res 1 is longer than res2 may be beneficial.

[0035] Especially, embodiments wherein res 1 is longer than res 2 and T 1 is lower than T2 may be advantageous for several reasons including better oil yields as well as it allows for a flexible process and plant design without requirements for e.g. high flow speed through the first stage. A longer resl compared to res2 may allow for a treatment of the biomass+ oil / oilbased solvent+alcohol under milder conditions with e.g. lower temperature in the first stage than in the second stage.

[0036] In some embodiments the alcohol reactant is added to the primary slurry before and / or during the first reaction stage, The first reaction product is fed to and reacted in the second reaction stage, at T2 of 250 - 450C and Res 2 is 1 - 20 min and T1 < T2 and resl > res2, and optionally at least part of the second reaction product is recycled as oil solvent to be mixed with the biomass to form the primary slurry. In some embodiments no alcohol is added between the first and second stage in order to achieve a produced biooil with improved properties such as higher oil yield and / or lower molecular weight.

[0037] In various embodiments the total pressure in the first and / or second reaction stage is 2 — 200 bar, such as 5 - 150 such as 20 - llObar. Such as or up to 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 bar. As a result of having oil and not water or alcohol as solvent during liquefaction it is possible to operate the process with low pressure compared to other known liquefaction techniques based on e.g. aqueous solvents which often are operated well above 200 bar. The use of an oil or an oilbased solvent will also in many embodiments result in a process which is less pressure sensitive allowing the method to be carried out across a wider range of pressures. The total pressure is

[0038] In some embodiments the pressure (i.e. total pressure) in the first reaction stage may be 1 - 5 bar such a 1 - 3 bar. A low pressure in the first stage may be particular advantageous in case of long first residence time Resl e.g. a resl of 30 - 150 min or even in case of a resl above 150min which for example may be advantageous if the first reaction stage is used as a store and / or mixing vessel. The total amount of alcohol added may be 5- 200 wt% such as 10 - 150 wt% such as 15 - 110%, such as 20, 40, 50, 60, 70, 80, 90, 100, 110 wt% of the dry weight (total weight less water content) of the primary slurry. In some embodiments the total amount of alcohol added may be 5 - 110wt%. Such as 5 - 100 wt%.

[0039] As alcohol isn't a traditional solvent (as used in solvent liquefaction) in the current liquefaction process but rather a reactant in at least the second stage if present, the alcohol concentration can be relatively low and / or have a limited partial pressure. The role of alcohol in the first reaction stage depends on parameters such as temperature in general when the alcohol is a liquid it may be present at least partly as solvent.

[0040] The ratio of alcohol: oil+biomass before or in the first reaction stage may for example be between 0:100 - 95:5 (wt%), such as or in between any of 5:95 or 10:90 or 15:85 or 20:80 or 30:70 or 40:60 or 50:50 or 60:40 : 80:20. In embodiments with a large excess of alcohol in the first stage such as e.g. 70:30 or higher it may be particular beneficial to remove at least part of the alcohol before the second reaction stage.

[0041] The ratio of alcohokoil+biomass before or in the second reaction stage may for example be between 0:100 - 50:50 (wt%), such as 5:95 or 10:90 or 15:85 or 20:80 or 30:70 or 40:60. In some embodiments the alcohol: oil+biomass ratio may be lower in the second reaction stage than in the first.

[0042] The ratio of alcohol: oil+biomass before or in the third reaction stage may for example be between 2:98 - 50:50 (wt%), such as 5:95 or 10:90 or 15:85 or 20:80 or 30:70 or 40:60 (wt%).

[0043] At least part of the first, second and / or third reaction product may be sent to further processing such as upgrade, stabilization, filtration, separation etc. In some embodiments the second reaction stage is the last reaction stage in other embodiments the third stage is the last reaction stage.

[0044] In some embodiments at least part of the first, second and / or third reaction product is recycled to upstream the first, second and / or third stage. In some embodiments at least part of the first, second and / or third reaction product is recycled as oil solvent to be mixed with the biomass to form the primary slurry. In some embodiments all of the first reaction product is fed to the second stage this is for example the case when no part of the first reaction product is sent to further processing or is recirculated. This may e.g. be beneficial in order to obtain a reaction product bio-oil with reduced acidity and improved stability prior to recirculation or further processing.

[0045] Applicant has shown that quite surprisingly even when no components such as e.g. water, alcohol and / or oil fractions is removed from the first reaction product before being fed to the second reaction stage after the first reaction stage is carried out (i.e. when all of the first reaction product is fed to the second stage), the method still results in a clearly improved second reaction product. For example when alcohol is present in the first reaction stage (i.e. added before and / or in the first reaction stage) and all of the first reaction product including alcohol and produced gasses, liquids and solids is fed to the second reaction stage an improved product and process is achieved compared to known processes in which oil, biomass and alcohol is reacted in a single step process or compared to processes requiring separation of e.g. water, alcohol, solids and / or fractions of produced oil before a liquefaction stage. This improvement is surprisingly observed over a wide range of Tl, Res 1, T2 and Res2.

[0046] Notably the process where alcohol is present in the first reaction stage and all of the first reaction product is fed to and reacted in the second reaction stage results in e.g. higher oil yield and / or an improved mass distribution of the components in the produced oil for Tl up to at least 250C such as at least 220C and down to 120C or lower such as down to HOC or even 80C and a T2 down to 300C or even lower and up to at least 330C such as 340C or 350C.

[0047] In some embodiments all of the second reaction product is fed to the third stage this is for example the case when no part of the second reaction product is sent to further processing or is recirculated before second reaction product is fed to a third stage. This may be beneficial in order to obtain a reaction product bio-oil with reduced acidity and improved stability prior to recirculation or further processing.

[0048] In other embodiments the oil solvent comprises at least partly the at least part of the first, second and / or third reaction product recycled to upstream the first, second and / or third stage. The present method may advantageously be used if the biomass is straw, woodchip etc. Including biomass such as wood, chips, sawdust, paper, forest residue, biogas digestate or lumber production wastes, straw feedstocks such as wheat, barley, oat, rye, canola, rape, rice and corn straw (including stover), energy grasses, biorefinery or other biomassprocessing residuals. The biomass may be plant waste from agriculture such as straw waste, corn stalks, and other residual products after food productions. The Biomass may for example also be wood waste from forestry and the timber industry such as residual biomass after wood production or production of wood-based products such as wood chip or wood pellets. Other examples of usable biomass include various residual products from paper production such as pulp or different type of lignin. Preferably the biomass is rich in lignin or is even comprised of relatively pure lignin such as up to 99,5% lignin such as up to 95% with trace amounts of cellulose, hemicellulose, water, minerals and / or ash etc .

[0049] The biomass may be of a single kind or may comprise more than one type of biomass.

[0050] The water content in the biomass may be 0 - 50%, such as 0,5 - 40%. Often it is beneficial if the biomass is relatively dry which means a water content below 15% such as 0 - 14%. Such as 2 - 10%. Such as or up to 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 wt%. When a biomass with a water content above 0% is used it is e.g. due to cost considerations as the cost in energy to dry the biomass may outweigh the negatives of having some water in the biomass.

[0051] During the liquefaction reaction water may be formed from reactions as well as it may be released from the biomass. However, at reaction conditions there is preferably no separate water phase in particular preferably no liquid water phase in reaction stages in particular in the second reaction stage where the temperature is higher.

[0052] Preferably no water is actively added to the process as water may have undesired effects. This means that any water in the reaction stages in some embodiments preferably is from biomass which may not be 100% dry and / or it may be water which is formed in the liquefaction process in the reaction stages and thus will be part of the solvent oil or product oil and preferably will not form a liquid water phase or be in a supercritical stage at reaction conditions. The ratio between oil and biomass in the primary slurry before the first reaction stage is preferably approximately 35wt% oil: 65wt% biomass (dry mass i.e. total weight less water content) - 85wt% oil: 15wt% biomass (dry mass), such as 40wt%:60wt%, such as 50wt%:50wt%, such as 60wt%:40wt%. In principle the biomass loading can also be very low such as 2 or 5wt% however this will result in a low efficiency of the process. An advantage of the present process is that high biomass loadings may be processed as solvent i.e. oil will be produced during the reaction stages resulting in that the ratio between oil and biomass may increase throughout the process.

[0053] Furthermore, the method may be advantageous if the alcohol has a lower boiling point than the oil remainder of the slurry for ease of downstream separation and generally cost of the alcohol.

[0054] The present application also relates to a plant for carrying out the process described herein.

[0055] In some embodiments the first and / or second stages are carried out in a reaction volume such as a reactor having a volume of e.g. 1 - 100m3.

[0056] In some embodiments the first stage is at least partly carried out in a storage or accumulation area, slurry preparation area and / or mixing area from where the first reaction product or a part of the first reaction product, is provided to the second reaction stage.

[0057] The plant further comprises means for heating the primary slurry and / or means for heating the at least part of the first reaction product before the second reaction stage. Alternatively, or in combination the plant comprises means for heating the first and / or second reaction stage.

[0058] The plant further comprises means for pressurizing and regulating pressure, such as valves,

[0059] Example 1

[0060] In a series of examples it has been shown that a thermal liquefaction process wherein biomass is converted to biooil in a two stage process is advantageous over a single stage liquefaction process. Beech wood powder (<150 pm) was used as the reference biomass throughout this experimental campaign. The biomass contained 4.9 wt.% moisture and 0.7 wt.% ash. Elemental analysis indicated carbon and hydrogen contents of 46.9%, 5.6%, respectively. Nitrogen was not detected in this biomass, while oxygen content was separately measured to be 47.5%. The model oil liquefaction solvent used for this work was a Kiln Fired Wood Tar from Linoliel23 (CAS: 8011-48-1). Pure ethanol was used as liquefaction co-solvent (>99.5, CAS: 64-17-5). 2-Methyltetrahydrofuran (2-MeTHF, >99%, CAS: 96-47-9) was used as a solvent to recover liquefaction products, by solvent assisted filtration after the second stage.

[0061] A 600 mL HT 4545 Parr stirred batch reactor was used for the liquefaction experiments. Approximately 160 g of feed was charged to the reactor. The biomass used in all the experiments is beech wood powder. The feed composition was kept the same for all the experiment being: 27.5 wt. % of biomass, 65.0 wt. % of wood tar, and 7.5 wt. % of absolute ethanol. After loading the feed slurry to the reactor, it was flushed three times with nitrogen to create an inert overhead volume. Heating was applied through a 2000 W electric band heater. A constant stirring of approximately 280-290 RPM was applied during heat-up, reaction duration and cooling. No biomass, oil, solid, gases or alcohol etc is removed or added between the first and second reaction stage as the reactor is kept closed.

[0062] The solid yield is determined based on the measured mass of solids from the solvent assisted filtration and the mass of biomass on a dry and ash-free basis. It is assumed that the ash in the fed biomass is entirely concentrated in the solid product.

[0063] The yield of the bio oil (Oil) product is estimated through Equation 2, where m(Tot oil) is the mass of total filtered oil recovered after reaction and m(S0) is the mass of start oil in the feed slurry. The recovered oil is assumed to be dry-ash free.

[0064] From this it is seen that all the experiments 1 - 5 with two stages have a higher oil yield than the single stage reference experiment. For all of the experiments 1 - 5 oi 13 yield is higher than the reference indicating that temperatures above and below the temperatures used will still provide beneficial results i.e. temperatures T1 below 120C and above 200C is indicated as relevant such as 120 - 200C + / - at least 15%. Similar for the residence time where Resl above and below 20 - 120min is expected to be relevant such as residence times of + / - 15% of 20 - 120 is expected to be relevant. In particular results indicates that even though residence times in the first stage i.e. Resl of 20 - 120min are beneficial residence times significantly above 120 mins is based on experiments expected to also provide an improvement with respect to the reference sample based on the results.

[0065] It should be noted that for Exp 3 and 4 it is expected that the oil yield is underestimated as not all liquid reaction product was fully recovered. However even with this uncertainty the data also shows that T1 of 120C and 150C is better than 200C with respect to solid yield. That T1 of 150 may have advantages for solid and oil yield over higher T1 for both short and long Res 1 is supported by results from Exp 6. Exp 6 experienced issues with temperature control resulting in temperature overshoot and faulty temperature ramps. As a result T1 was significantly higher than the planned 200C and the alcohol, biomass, oil mix was subject to a T1 of approximately 250C. Furthermore, the time it took to reach T2 after the first reaction was significantly higher than for Exp 1 - 5. At these higher values for T1 and res 2 the solid yield was higher and oil yield was lower than for Tl of 120C and 150C.

[0066] However, on other parameters Exp 6 is still advantageous over the reference (single stage reaction). For example, the mass distribution of the components in the produced oil from Exp 6 is improved i.e. shifted towards lower molecular mass when the method comprises a first and second reaction step with alcohol even when the results are less advantageous when it comes to solids and oil yield as seen in fig 5 comparing the reference experiment with exp 6.

[0067] TAN of the biooils produced in Exp 1 - 5 is within the range of 35 - 50 mg KOH / g which is similar to TAN of biooil produced by single step solvothermal liquefaction of biomass in oil solvent with alcohol reactant.

[0068] Comparison of mass distribution of produced oil was also used to see the effect of differences in T2. It was observed that a T2 of both 300C and 330C (with a Tl=150, Res l=120min, Res2=20min) provides a significant improvement over the single stage reference experiment (Tl=150, Res l=120min, Res2=20min). However, a T2 of 330C results in a slightly lower mass distribution compared to T2=300C showing that a two-stage process as in this series of experiments is providing an improved product for T2 temperatures down to 300C or lower and up to at least 330C but a T2 of at least 330C may provide better results than 300C.

[0069] Experiment 2

[0070] It has been shown that treatment of biooil from a thermal liquefaction of biomass using an oil solvent with alcohol reactant reduces the TAN of the biooil while at least maintaining the stability and other advantageous parameter of the biooil.

[0071] It can be concluded that treating a biooil produced by thermal liquefaction of biomass in oil with added alcohol can reduce the TAN of the biooil. It is interesting that this is still the case even when the biooil is produced in a process wherein alcohol is used as a reactant with oil as the main solvent. Results have shown that both ethanol and methanol provide a significant reduction in TAN of the biooils. Similar experiments by applicant show that 2- propanol also provides a reduction of TAN of the biooils however the reduction isn't as significant as observed for both methanol and ethanol confirming that short chained preferably primary alcohols are advantageously used.

[0072] This means that a third stage wherein the biooil produced in the first and second stage is treated in alcohol may be advantageous in order to lower TAN of the produced biooil in the second product stream obtained from the second stage if desired.

[0073] Description of the drawings

[0074] Fig 1 shows schematic overview of elements of the method

[0075] Fig 2 illustrates a first embodiment of the present invention

[0076] Fig 3 illustrates a second embodiment of the present invention

[0077] Fig 4 illustrates a third embodiment of the present invention

[0078] Fig. 5 Mass distribution spectrum Detailed description of the invention

[0079] Fig 1 shows a schematic overview of elements of the method for controlled production of biooil 1. The process is illustrated with three consecutive reaction stages: first reaction stage SI, second reaction stage S2, third reaction stage S3. In a mixing point 2 biomass 3 and oil 4 is mixed to form a primary slurry. The primary slurry is fed to the first reaction stage where it is reacted to form a first reaction product which is fed to the second reaction stage where it is reacted to form a third reaction product which is send downstream 5 for further processing, storage, separation and / or recirculation for example by providing it as the oil in the mixing point. Alcohol can be added to the primary slurry, first reaction product and / or second reaction product indicated by arrows Al, Alb, A2, A2b, A3 , A3b. Al illustrates addition of alcohol before the first reaction step and Alb illustrates the addition of alcohol to the first reaction stage. It is possible to add alcohol both before and in the first reaction step as well as either before Al or in Alb the first reaction step. Similarly, alcohol can be added before and / or after to each of the second and third reaction stage A2, A2b, A3, A3b.

[0080] Alcohol may also be separated from the first, second and / or third reaction products here illustrated with arrow A4 between the first and the second reaction stage.

[0081] Parts of the first, second and / or third reaction products may be separated out and send e.g. for further processing, recirculation etc as indicated by 6.

[0082] Each reaction stage SI, S2, S3 are defined at least by process parameters temperature Tl, T2, T3 and residence time Resl, Res2, Res3.

[0083] Fig. 2 illustrates an embodiment of the present invention wherein biomass 3 and oil is mixed in a mixing point 2 forming a primary slurry. Alcohol in form of ethanol is added Al before the first reaction stage SI. In the first reaction stage SI the primary slurry is reacted at temperature Tl for a residence time Resl forming a first reaction product which leaves reaction stage 1 and is fed to a second reaction stage S2. In reaction stage 2 the first reaction product is reacted at temperature T2 for a residence time Res2 forming a second reaction product which leaves the second reaction stage. As seen no part of the first product oil (reaction product) or alcohol is removed before reaction in stage 2.

[0084] Fig. 3 illustrates an embodiment of the present invention wherein biomass 3 and oil 4 is mixed in a mixing point 2 forming a primary slurry. Alcohol in form of ethanol is added Al before the first reaction stage SI. In the first reaction stage SI the primary slurry is reacted at temperature T1 for a residence time Resl forming a first reaction product which leaves reaction stage 1 and is fed to a second reaction stage S2. Before the first reaction product is fed to the second reaction stage all or substantially all alcohol is removed A4 from the first reaction product. In the second reaction stage S2 the first reaction product is reacted to form a second reaction product. The second reaction product is fed to the third reaction stage S3. Before entering the third reaction stage S3 alcohol is added A3 to the second reaction product. In the third reaction stage S3 the second reaction product and alcohol is reacted to form a third reaction product which leaves the third reaction stage.

[0085] In the current embodiment optionally part of the second reaction product is separated out as indicated by 6. The part separated from of the second reaction product may for example be recirculated and / or send to further processing.

[0086] Fig. 4 illustrates an embodiment of the present invention wherein biomass 3 and oil 4 is mixed in a mixing point 2 forming a primary slurry. In the first reaction stage SI the primary slurry is reacted at temperature T1 for a residence time Resl forming a first reaction product which leaves reaction stage 1 and is fed to a second reaction stage S2. Alcohol in form of ethanol is added A2 before the second reaction stage S2. In reaction stage 2 the first reaction product and alcohol are reacted at temperature T2 for a residence time Res2 forming a second reaction product which leaves the second reaction stage.

Claims

1. CLAIMS1. A method for production of biooil by thermal liquefaction of a lignocellulosic biomass, the method comprising the steps ofProviding the lignocellulosic biomassMixing the lignocellulosic biomass with an oil or oilbased solvent, preferably a biooil, to obtain a primary slurryReacting the primary slurry in a first reaction stage at temperature Tl, residence time resl obtaining a first reaction productReacting at least part of the first reaction product in a second stage at temperature T2, residence time res2 obtaining a second reaction product andAdding an alcohol reactant to the primary slurry before and / or during the first stage and / or to the first reaction product before and / or during the second stage.

2. Method according to claim 1 wherein the alcohol reactant is a short chained primary alcohol, preferably ethanol and / or methanol.

3. Method according to any of the preceding claims comprising the step of reacting at least part of the second reaction product in a third stage at temperature T3 and residence time res3 obtaining a third reaction product.

4. Method according to any of the preceding claims comprising the step of adding the alcohol reactant to the second reaction product before and / or during the third stage.

5. Method according to any of the preceding claims, wherein the total amount of alcohol added is 5- 200 wt% such as 10 - 150 wt% such as 15 - 110%, such as 20, 40, 50, 60, 70, 80, 90, 100, 110 wt% of the dry weight of the primary slurry.

6. Method according to any of the preceding claims, wherein at least part of the first, second and / or third reaction product is sent to further processing.

7. Method according to any of the preceding claims, wherein at least part of the first, second and / or third reaction product is recycled to upstream the first, second and / or third stage and / or wherein at least part of the first, second and / or third reaction product is recycled as oil solvent to be mixed with the biomass to form the primary slurry.

8. Method according to any of the preceding claims, wherein all of the first reaction product is fed to the second stage.

9. Method according to any of the preceding claims, wherein T1 is 120 - 300C, and / or wherein T2 is 250 - 450C, such as 270 - 350C and / or wherein T3 is 250 - 350C.

10. Method according to any of the preceding claims, wherein T1 < T2 and / or T3 < T2 and / or wherein resl > res2.

11. Method according to any of the preceding claims, wherein:The alcohol reactant is added to the primary slurry before and / or during the first reaction stage,The first reaction product is fed to and reacted in the second reaction stage,T2 is 250 - 450C and Res 2 is 1 - 20 min,T1 < T2 and, such as Tl<250C, and wherein resl > res2.

12. Method according to any of the preceding claims, wherein T1 is 80C - 150C and / or wherein Resl is at least 90min.

13. Method according to any of the preceding claims, wherein T1 is 100 - 150C and wherein Resl is at least 10 - 240 min, such as 10 - 240min.

14. Method according to any of the preceding claims, wherein the first stage is at least partly carried out in a storage or accumulation area, slurry preparation area and / or mixing area from where the first reaction product or a part of the first reaction product, is provided to the second reaction stage.

15. Method according to any of the preceding claims, wherein the alcohokoil+biomass ratio is lower in the second reaction stage than in the first reaction stage.

16. Method according to any of the preceding claims, wherein total pressure in the first and / or second reaction stage is 2 - 200 bar, such as 5 - 150 such as 20 - llObar.Such as or up to 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 bar and / or wherein the pressure in the first reaction stage is 1 - 5 bar such a 1 - 3 bar.

17. Method according to any of the preceding claims, wherein there is no separate water phase, in particular no liquid water phase, in the second reaction stage.

18. Plant for controlled production of biooil by thermal liquefaction of a lignocellulosic biomass comprising:A first reaction stage and a second reaction stageA mixing point arranged for mixing biooil and biomass to a primary slurry Means for feeding the primary slurry to the first reaction stageMeans for feeding a first reaction product or at least part of a first reaction product formed in the first reaction stage to the second reaction stage, At least one alcohol addition point adapted for adding an alcohol reactant to the primary slurry before and / or during the first stage and / or to the first reaction product before and / or during the second stage.

19. Plant according to claim 18, wherein the at least one alcohol addition point is arranged before the first reaction stage.

20. Plant according to claim 18 or 19, arranged to carry out the method of claims 1 - 17.

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